Small Hospital/Clinic Medical Equipment & Diagnostics Training Manual

1. ESSENTIAL MEDICAL EQUIPMENT

Vital Signs Monitoring

Pulse Oximetry (SpO2)

Normal range: 95-100% at sea level
Red flag zones: <90% hypoxemia; <85% severe; <80% critical emergency
Technique: Place sensor on finger, toe, ear, or nose bridge; wait 20 seconds for reading
Limitations: Inaccurate with hypoperfusion, severe anemia (<7g/dL), CO poisoning (falsely high), nail polish, hypothermia
Waveform: Pulse bar indicates adequate signal; absent waveform = no perfusion
Alarm settings: Set high alarm 92-94%, low alarm 90%

Blood Pressure Monitoring

Manual (auscultatory):
- Cuff size: bladder encircles 80% of arm; wrong size = error (too small = falsely high, too large = falsely low)
- Korotkoff sounds: First appearance = systolic; muffling = diastolic (use muffling in pregnancy, aortic regurg)
- Take in both arms; document position (sitting/lying); use arm at heart level
Automated: Less accurate with arrhythmias, tremor; easier for repeated measurements
Normal ranges: Systolic <120 mmHg, Diastolic <80 mmHg
Hypertension: Stage 1 ≥130/80, Stage 2 ≥140/90; Crisis ≥180/120 with symptoms
Hypotension: <90/60 concerning; <80/50 in shock state

Temperature

Axillary: 36.5°C (97.7°F) - affected by skin temperature, time taken
Oral: 37°C (98.6°F) - unreliable with mouth breathing, recent drinking
Tympanic (ear): 37.5°C - prone to cerumen impaction error
Rectal: 37.5°C (99.5°F) - most accurate but invasive
Fever: >38°C oral; <36°C hypothermia (danger)
Note: Antipyretics may mask infection; don’t routinely treat fever <38.5°C in stable patients

Cardiac Monitors (Continuous)

Placement: Electrodes in 3-5 lead positions on chest wall (avoid breast tissue, wounds, scars)
Lead II: Standard for arrhythmia detection; best P-wave and QRS visualization
Waveforms interpreted: HR, rhythm (regular/irregular), QRS width, P-T relationship
Ensure good contact: Skin prep with gauze/alcohol; replace gels daily; avoid diaphoresis interference
Alarm fatigue: Adjust sensitivity to reduce false alarms while detecting real changes

ECG/EKG Fundamentals

12-Lead ECG Basics

Lead placement: RA (right arm), LA (left arm), LL (left leg), RL (right leg ground), V1-V6 precordial
Paper speed: 25 mm/sec standard; 1 mm = 0.04 sec horizontally, 0.1 mV vertically
Intervals:
- PR: 120-200 ms (0.12-0.20 sec); prolonged = AV block, short = WPW
- QRS: <120 ms normal; ≥120 ms = RBBB/LBBB or PVC
- QT: 350-450 ms corrected (QTc); prolongation = arrhythmia risk, drug effect, hypocalcemia
Segments: ST segment elevation/depression indicates ischemia; T-wave inversion = recent MI or PE

Normal Sinus Rhythm

Rate 60-100 bpm
Regular RR intervals
P-wave before each QRS, upright in II, V4-V6
PR interval constant
QRS width <120 ms

Common Arrhythmias

Sinus Tachycardia: Rate >100; regular; P before each QRS. Causes: fever, pain, anemia, PE, thyroid, sepsis. Tx: treat underlying cause.

Sinus Bradycardia: Rate <60; regular; normal waveforms. Causes: sleep, athletes, hypothermia, MI, drugs (beta-blockers, digoxin), increased ICP. Tx: pacing if symptomatic.

Atrial Fibrillation: Irregular RR intervals; absent P-waves; chaotic baseline. Complications: stroke (CHA2DS2-VASc score determines anticoagulation), RVR (>100 bpm). Tx: rate control (beta-blockers, CCB, digoxin) or rhythm control (amiodarone, procainamide).

Atrial Flutter: Regular or regularly irregular rate (usually 150); flutter waves (saw-tooth baseline); typically 2:1 conduction. Tx: similar to AFib.

Supraventricular Tachycardia (SVT): Rate 140-250; narrow QRS; sudden onset/termination; P-wave often buried in T-wave. Causes: AVNRT, AVRT, atrial tach. Acute tx: vagal maneuvers (Valsalva), adenosine IV, CCB. Maintenance: beta-blockers.

Premature Ventricular Contraction (PVC): Wide QRS (≥120 ms) not preceded by P-wave; occurs early; full compensatory pause. Single: benign if no CAD. Frequent (>6/min) or bigeminy/trigeminy in acute MI = dangerous. Tx: beta-blockers; amiodarone if symptomatic.

Ventricular Tachycardia (VT): Rate >120; wide QRS; regular or irregular; AV dissociation (best sign). Pulseless VT = cardiac arrest = defibrillate. Pulsed VT = amiodarone IV + synchronized cardioversion. Distinguish from SVT with aberrancy: VT has fusion beats, AV dissoc, extreme QRS axis.

Ventricular Fibrillation (VFib): Chaotic, no organized complexes. Cardiac arrest rhythm = defibrillate immediately, CPR.

Asystole: Flat line; confirms in two leads; pacing ineffective; poor prognosis. Continue CPR, epinephrine, reversible causes (HHHHH: Hypoxia, Hypovolemia, Hydrogen/acidosis, Hyper/hypokalemia, Hypothermia).

Bradycardia with Block:

1st degree: PR >200 ms; all impulses conduct; benign
2nd degree Mobitz I (Wenckebach): Progressive PR prolongation until dropped beat; usually benign; no pacing needed
2nd degree Mobitz II: Fixed PR with occasional dropped beats; dangerous; may need pacing
3rd degree (complete): No P-QRS relationship; escape rate sets HR; must pace

STEMI Recognition

Location: Anterior (V1-V4), Inferior (II, III, aVF), Lateral (I, aVL, V5-V6), Posterior (V7-V9 tall R, ST depression in V1-V3)
ST elevation ≥1 mm in two contiguous leads (or 2 mm in V1-V2) = STEMI diagnosis
Posterior STEMI: Tall R in V2, ST depression V1-V3; confirm with V7-V9 (ST elevation)
Reciprocal changes: ST depression opposite territory (diagnostic clue)
Time-sensitive: Door-to-balloon <90 minutes (PCI) or door-to-needle <30 min (thrombolytics)
Complications: Cardiogenic shock, heart blocks, mechanical (rupture, VSD, papillary muscle rupture)

Mechanical Ventilation

Ventilator Types

Microprocessor-based: Complex, full-featured; ICU-grade; can weaning protocols
Volume-cycled: Delivers set tidal volume; pressure variable
Pressure-cycled: Limits pressure; volume variable; used in transport, home care
Time-cycled: Neonatal ventilators

Ventilation Modes

CMV (Controlled Mandatory Ventilation):

Machine delivers every breath at set rate
No spontaneous breathing allowed
Use: apnea, paralyzed, heavy sedation
Set: Rate (10-16 bpm), Tidal Volume (6-8 mL/kg IBW), PEEP 5 cmH2O

AC (Assist-Control):

Set backup rate; patient can trigger additional breaths at same volume
Most common initial mode
Risk: breath stacking if breathing over mode, hyperventilation
Set: Rate, TV, triggering sensitivity (-1 to -2 cmH2O)

SIMV (Synchronized Intermittent Mandatory Ventilation):

Delivers set mandatory breaths; between mandatory breaths, patient breathes spontaneously (unsupported unless PSV added)
Better for weaning
Requires adequate respiratory drive
Set: Rate, TV, PSV level if desired (5-10 cmH2O)

PSV (Pressure Support Ventilation):

All breaths patient-triggered; positive pressure to reduce WOB
Requires adequate respiratory drive
Risk: apnea if patient tires
Use: weaning, spontaneous breathing trials
Set: PSV level 5-25 cmH2O (start 10-15); PEEP 5

CPAP/PEEP:

CPAP: continuous positive airway pressure; all spontaneous breaths
PEEP: positive end-expiratory pressure; holds alveoli open, improves oxygenation
Indications: ARDS (use PEEP 5-15), COPD exacerbation, cardiogenic pulmonary edema, pneumonia
Complications: barotrauma (pneumothorax), decreased CO if excessive (limit 15 cmH2O)

Settings & Monitoring

FiO2: Start 60%, titrate to SpO2 >88%; wean as tolerated
PEEP: Start 5 cmH2O; increase if SpO2 low despite FiO2; auto-PEEP in COPD (measure with expiratory hold)
Alarms: Set high pressure alarm (25-30 cmH2O), low minute ventilation, disconnect
Humidification: Essential; heated circuits prevent condensation (VAP prevention)
Ventilator-associated pneumonia: Oral care, semi-recumbent position, VAP bundle, early mobility

Troubleshooting: Desaturation/Hypoxemia During Ventilation

Check settings (FiO2 <60%, PEEP appropriate?)
Suction airway (occluded tube, secretions)
Check ventilator function (tubing kinked, disconnected, settings drifted)
Lung recruitment: increase PEEP, increase FiO2, increase TV if possible
Pathology: pneumonia, ARDS, pneumothorax, pulmonary edema, atelectasis—consider CXR, blood gas

Weaning Parameters

RSBI (Respiratory rate / Tidal volume): <105 = can wean
ABG: pH 7.35-7.45, PaCO2 35-45 (tolerate higher in COPD)
FiO2 <40%, PEEP <5
Hemodynamically stable, no new sepsis
Spontaneous breathing trial: 2 hours T-piece or low PSV/PEEP; if tolerates = extubate candidate

Defibrillation

AED (Automated External Defibrillator)

Use: Unresponsive patient without pulse + cardiac arrest (VFib, pulseless VT)
Procedure: Turn on, expose chest, place pads (right upper chest, left midaxillary line V6 level), do not touch patient, analyze rhythm, shock if indicated
CPR between shocks: 2 minutes cycles
Contraindications: Patient on water/wet environment (delay), transdermal patch at pad site (move pad), implanted pacemaker (place pad >1 inch away)
Success: Defibrillation converts VFib to perfusing rhythm in ~70% if <3 minutes

Manual Defibrillation (Synchronized & Unsynchronized)

Unsynchronized (Defibrillation): VFib, pulseless VT → immediate shock, no delay for sync
- Initial dose: 200 J (biphasic) or 360 J (monophasic)
- Escalate: 200-300 J biphasic per protocol
Synchronized Cardioversion: Hemodynamically unstable with pulse (SVT, AFib with RVR, VT with pulse, atrial flutter)
- Press sync button; machine detects QRS, delivers shock on QRS downstroke (prevents VFib from T-wave shock)
- Initial dose: 50-100 J; escalate by 100 J
- Sedate first if conscious (midazolam 2-5 mg, fentanyl 1 mcg/kg IV)

Suction Devices

Types: Wall suction (hospital), portable suction (battery/hand-crank, ambubag-powered), tonsil suction (Yankauer)
Pressure: Wall suction 80-120 mmHg (set regulator); portable 60-80 mmHg
Catheter sizes: 10-14 Fr for adults (oropharynx), 12-18 Fr for airway/nasopharynx
Technique: Pre-oxygenate, insert gently without applying suction, apply suction only on withdrawal, limit to 10-15 seconds, allow recovery between passes
Complications: Hypoxemia (suction removes oxygen), mucosal trauma (gentle), aspiration if inadequate airway protection
Maintenance: Flush with sterile water after each use; check tubing integrity; replace catheter if kinked

IV Pumps & Infusions

Gravity drip: Flow depends on hydrostatic pressure, needle gauge, fluid viscosity; not precise
Infusion pump: Peristaltic (gentle, for fragile infusates) or piston (rapid, for viscous fluids)
Smart pumps: Drug library, dose limits, alerts for dosing errors; reduces medication errors
Rate calculation: mL/hr = (Total mL needed / Time in hours); e.g., 500 mL over 4 hours = 125 mL/hr
Complications: Infiltration (fluid leaking into tissues—stop, elevate, warm compress), extravasation (vesicant into tissues—emergency, treat per protocol), phlebitis (pain, erythema—restart elsewhere), sepsis (if contaminated)
Maintenance: Check tubing for kinks/air bubbles hourly; assess site daily; change dressing per protocol; max dwell time 72-96 hours

Oxygen Delivery Systems

Nasal Cannula:

1-6 L/min → 24-44% FiO2 (roughly 4% increase per 1 L/min)
Humidify >4 L/min to prevent nasal irritation
Comfortable for long-term; patient can eat/talk

Simple Face Mask:

5-8 L/min → 40-60% FiO2
Must use ≥5 L/min to prevent CO2 rebreathing
Covers mouth/nose; patients may feel claustrophobic

Partial Rebreather Mask:

6-15 L/min → 60-75% FiO2
Reservoir bag fills during expiration; first 1/3 exhaled air (dead space, rich in O2) enters bag
Bag should not collapse fully during inspiration (refill flow rate adequate)

Non-Rebreather Mask:

10-15 L/min → 80-95% FiO2
One-way valve prevents exhaled air from entering bag
Highest non-invasive FiO2; used in hypoxemia, acute illness
Fill bag completely before placing on face; maintain 1/3-1/2 fullness

High-Flow Nasal Cannula:

30-60 L/min → up to 100% FiO2 (heated/humidified)
Washout of anatomic dead space; reduces work of breathing; PEEP effect ~3-5 cmH2O
Tolerated better than high-flow masks; enables talking/eating
Use: pneumonia, ARDS, post-extubation, sepsis

Venturi Mask:

24-50% FiO2 (use appropriate adapter for desired FiO2)
Precise FiO2; use in COPD to prevent hypercapnia (risk of CO2 retention with high FiO2)
Must be snug fitting for accuracy

Bagging (Ambu/BVM):

Manual ventilation; 21% O2 (room air) without attached reservoir, ~40% with reservoir (ensure sealing), ~100% with reservoir + oxygen source
Technique: E-C clamp (thumb/index on mask, middle/ring/pinky on jaw), squeeze bag 1 second per 5-6 seconds (12 breaths/min)
Risks: gastric inflation (use cricoid pressure/Sellick maneuver in unconscious), inadequate seal, excessive pressure
Use: apnea, respiratory arrest, pre-oxygenation before intubation

Surgical Instruments: Identification & Care

Cutting Instruments:

Scalpel (sizes 10-25): precise cutting; surgical blade on handle
Scissors: straight (suture, tissue), curved (deeper tissues), Mayo (tough tissues)
Bone cutters, wire cutters (specialized)
Care: Hand-wash immediately, store with caps, sharpen regularly, autoclave safe

Grasping/Clamping:

Forceps (Adson toothed = delicate tissues, DeBakey = vessels, Russian = heavy tissues)
Hemostats (mosquito <10mm, Kelly 10-15mm, Rochester 15-20mm): clamp vessels
Retractors (hand-held or self-retaining): expose surgical field
Care: Open fully before autoclaving (esp. hinged instruments), check latch function

Probing/Exploring:

Periosteal elevator: bone work
Curette: scrape bone/tissue
Freer elevator: soft tissue dissection
Care: Protect tips (wrap in gauze if damaged)

Miscellaneous:

Needle holders (Mayo, Castroviejo): hold suture needles; locking mechanism
Suction tips (Frazier, Poole, Yankauer): different sizes for different cavities
Specula (ear, nasal, vaginal): visualization
Care: Needle holders wear out; test locking mechanism; replace if jaws misaligned

Sterilization & Storage:

Clean immediately with warm water (not cold; coagulates protein), scrub internal mechanisms with brush
Air-dry completely (moisture → rust)
Wrap instruments in single layers of surgical cloth (double-wrapping reduces steam penetration) or rigid containers
Autoclave: 121°C, 15-30 psi, 15-30 minutes (unwrapped faster; wrapped slower)
Store dry in clean, cool place; inspect before use (rust, spots = resterilize)

Ultrasound Basics

Machine Components

Transducer (probe): emits/receives sound waves; frequency 2-14 MHz (higher freq = better resolution, poor depth; lower = worse resolution, good depth)
Screen: real-time image
Presets: cardiac, abdo, OB, vascular (optimization of gain, frequency, pulse)
Doppler: measures blood flow velocity (positive = toward probe, negative = away)

FAST Exam (Focused Assessment with Sonography for Trauma)

Purpose: Detect free fluid (blood) in abdomen in trauma (sensitivity ~95% for >500 mL)
Technique: 4 views with 3.5-5 MHz transducer
1. Pericardial: Subxiphoid window; inferior vena cava long-axis; look for fluid (anechoic, black) between visceral/parietal pericardium (life-threatening tamponade)
2. Right upper quadrant (Morison’s pouch): Probe at 12th rib midaxillary; look for fluid between liver/kidney (most common site, >50% of ABD fluid)
3. Left upper quadrant: Probe at 11th rib midaxillary; look for fluid between spleen/kidney
4. Pelvic: Suprapubic window, longitudinal; look for fluid in pelvis (bladder full = darker, easier to see fluid)
Interpretation: Positive (≥4 views positive) → likely intra-abdominal bleeding → surgery. Serial FAST (repeat in 5-10 min) may detect progression.
Limitations: Obesity, bowel gas, recent surgery, subcapsular bleeding without free fluid

Basic POCUS (Point-of-Care Ultrasound)

Vascular access: Short-axis view (cross-section) shows vein, artery; guide needle in real-time (reduces infiltration)
Lung: B-lines (comet-tail artifacts) = interstitial edema (CHF, ARDS); A-lines = normal
IVC: Measure diameter, collapsibility (<50% collapse in spontaneous breathing = elevated central venous pressure); semi-quantitative fluid status
Cardiac: Ejection fraction (visual estimate), wall motion, pericardial effusion
Abdominal free fluid: As above; extra views for suspected appendicitis (inflamed appendix >6 mm), AAA (>3 cm = large)

2. LABORATORY DIAGNOSTICS

Point-of-Care Testing (POCT)

Glucose Testing

Purpose: Bedside screening for hypo/hyperglycemia; NOT diagnostic for diabetes
Technique: Finger prick (lancet, lateral pad of finger), apply blood drop to test strip, insert into glucometer
Normal fasting: 70-100 mg/dL (3.9-5.6 mmol/L)
Normal random: <140 mg/dL (<7.8 mmol/L)
Hypoglycemia: <70 mg/dL; symptoms >50-60 mg/dL (shakiness, confusion, tachycardia, sweating); treat with dextrose 15-20g (glucose tablets, juice), recheck in 15 min
Hyperglycemia: >300 mg/dL concerning; ketones = risk of DKA
Errors: Dehydration (falsely high), anemia (falsely low), altitude (varies)

Urine Dipstick

Components: Glucose (normal 0), protein (normal 0), nitrites (0 = no UTI), leukocyte esterase (0 = no WBC), blood (0), pH (4.5-8), specific gravity (1.005-1.030), ketones (0), bilirubin (0), urobilinogen (0-1)
Interpretation:
- Glucose +: Hyperglycemia (>180 mg/dL) or renal threshold low (pregnancy, congenital); NOT on low-carb diet
- Protein +: Kidney disease, infection, exercise, contamination; trace-1+ can be normal
- Nitrites + & Leuk esterase +: Strong UTI; 80% specific for bacteriuria
- Blood (RBC) + without protein/WBC: Hemoglobinuria or myoglobinuria
- RBC + with protein + & casts: Glomerulonephritis
- Specific gravity low (<1.010): Dilute urine (overhydration) or diabetes insipidus
- Specific gravity high (>1.030): Dehydration, contrast, high glucose
- Ketones +: DKA, starvation, low-carb diet
- Bilirubin +: Hemolysis or liver disease
Timing: Read at exact times per test type (usually 60-120 sec); fading colors = past expiration

Pregnancy Test (hCG)

Types: Urine (qualitative hCG) or serum (quantitative)
Sensitivity: Detects hCG >5-25 mIU/mL; 95% accurate on day of missed period
False negatives: Early testing (<5-7 days post-ovulation), ectopic (hCG rises slowly), miscarriage (hCG declining)
False positives: Rare; hCG-secreting tumors (molar pregnancy, choriocarcinoma), recent miscarriage (hCG lingers 4-6 weeks)
Serum beta-hCG: Quantitative; doubles every 48-72 hours in early pregnancy; plateau at 10-12 weeks; used to monitor viability

Rapid Strep Test (Group A Streptococcus)

Specimen: Throat swab (back of throat, tonsillar pillars)
Sensitivity: 90-95%; specificity 95%
Negative test + high clinical suspicion: Confirm with throat culture (24-48 hours)
Treatment: Penicillin V 500 mg QID x10 days (or amoxicillin); if penicillin-allergy → azithromycin or 1st gen cephalosporin (10% cross-reactivity with PCN)
Indications for testing: Fever + pharyngitis + exudate (not for cough alone, nasal symptoms, viral prodrome signs)

Malaria Rapid Diagnostic Test (RDT)

Types: Target HRP2 (P. falciparum), pLDH (all species), aldolase (all species)
Sensitivity: 95-99% for P. falciparum; lower for other species; negative in <100 parasites/μL
Procedure: Finger prick → blood drop on cassette → add buffer → read at 15-20 minutes
Interpretation:
- Control line only: Negative
- Control + species lines: Positive (mix = multiple species possible)
Confirm with microscopy: RDT may remain positive weeks after treatment (PCR confirms active infection)
False positives: Cross-reactivity, rheumatoid factor
False negatives: <100 parasites/μL, non-immune travelers (delay in symptoms)

HIV Rapid Test

Types: Antibody (detects anti-HIV IgG, >18 days post-infection), antigen-antibody (detects HIV Ag + Ab, ~11 days), nucleic acid test/NAT (detects RNA, ~10 days—most sensitive)
Procedure: Finger prick or oral fluid → test cassette → read 15-20 minutes
Interpretation: 2 lines = positive, 1 line (control) = negative, no lines = invalid
Window period: Negative test doesn’t exclude recent infection; retest at 28 days if high-risk exposure
Confirmation: All positive tests need Western blot, ELISA, or HIV-1/2 differentiation test; results are NOT diagnostic until confirmed by reference lab
False positives: Cross-reactivity with other retroviruses (rare), technical error; re-test always

Complete Blood Count (CBC) Interpretation

WBC (White Blood Cell) Count:

Normal: 4.5-11.0 × 10^9/L (× 10^3/μL)
Elevated (Leukocytosis) >11: Infection (bacterial most common), inflammation, leukemia, drugs (steroids, epinephrine)
Decreased (Leukopenia) <4.5: Bone marrow suppression (chemotherapy, radiation, aplastic anemia), sepsis (paradoxically in severe), immune destruction, B12/folate deficiency, medications (sulfas, allopurinol)
Left shift: Increased bands (immature neutrophils) = acute infection/stress

Differential (% of total WBC):

Neutrophils 50-70%: Phagocytes; increased = bacterial infection, stress
Lymphocytes 20-40%: Immunity; increased = viral infection, leukemia; decreased = HIV, steroids
Monocytes 2-8%: Cleanup cells; increased = chronic infection, monocytic leukemia
Eosinophils 1-4%: Parasites, allergy; increased = parasitic infection, asthma, eosinophilia
Basophils <1%: Rarely elevated

RBC (Red Blood Cell) Count:

Normal: 4.5-5.5 × 10^12/L (men), 4.0-5.0 (women)
Elevated: Polycythemia (EPO-secreting tumor, smoking, altitude, dehydration)
Decreased: Anemia; see Hemoglobin below

Hemoglobin (Hgb):

Normal: 13.5-17.5 g/dL (men), 12.0-15.5 (women)
Anemia classification:
- Mild: 10-12 g/dL (symptoms usually absent)
- Moderate: 7-10 g/dL (dyspnea, tachycardia at rest)
- Severe: <7 g/dL (high-output heart failure, syncope risk; transfuse if symptomatic)
Causes: Iron deficiency (microcytic, low MCV), B12/folate (macrocytic), hemolysis (elevated retic), bleeding, bone marrow disease
Acute blood loss rule: Hgb drops 1 g/dL per 500 mL loss (lags behind actual volume loss by 24-48 hours)

Hematocrit (Hct):

Normal: 41-50% (men), 36-45% (women)
Significance: Rough estimate; actual RBC mass better reflected by hemoglobin

MCV (Mean Corpuscular Volume):

Normal: 80-100 fL
Microcytic (<80): Iron deficiency, thalassemia, sideroblastic anemia
Macrocytic (>100): B12 deficiency, folate deficiency, hypothyroidism, EtOH, medication
Normocytic (80-100): Acute bleeding, hemolysis, bone marrow disease

Platelets:

Normal: 150-400 × 10^9/L
Thrombocytopenia (<150): ITP (immune), TTP (microangiopathic hemolytic anemia + thrombocytopenia), HUS, DIC (coagulopathy + low plt), drugs, sepsis, dilution (massive transfusion)
- Mild (<100): Monitor
- Moderate (50-100): Increased bleeding risk
- Severe (<50): Spontaneous bleeding risk; transfuse if <10-20 or symptomatic
Thrombocytosis (>400): Iron deficiency, inflammation, malignancy, post-splenectomy

Reticulocyte Count:

Normal: 0.5-2% of RBCs
Elevated: Bone marrow responding to anemia (good prognosis) or hemolysis
Low in anemic patient: Bone marrow failure (aplasia, iron deficiency without response)

Basic Metabolic Panel (BMP) & Comprehensive Metabolic Panel (CMP)

Sodium (Na+):

Normal: 135-145 mEq/L
Hypernatremia (>145): Dehydration (free water deficit), hyperglycemia (osmotic diuresis), DI, excessive saline IV
- Sx: thirst, confusion, seizures if acute/severe
- Tx: slow rehydration (half correction in 48h; rapid = cerebral edema)
Hyponatremia (<135): SIADH, heart/liver/kidney disease, excessive hypotonic fluids, adrenal insufficiency, psychogenic polydipsia
- Mild asymptomatic: monitor
- Symptomatic or severe: hypertonic saline 3% slow (sodium correction max 10-12 mEq/L per 24h; rapid = osmotic demyelination)

Potassium (K+):

Normal: 3.5-5.0 mEq/L
Hyperkalemia (>5.0): Renal disease, ACE-I, aldosterone blockers, rhabdomyolysis (tumor lysis, crush), acidosis, hemolysis (spurious—check for lab error)
- EKG signs: Peaked T-waves, widened QRS, lost P-wave (>6.5), VFib
- Tx: Calcium gluconate (cardiac stabilization), insulin + dextrose (shift K intracellularly), beta-agonists, sodium polystyrene sulfonate (Kayexalate, dialysis if severe)
Hypokalemia (<3.5): Diuretics, diarrhea, alkalosis (insulin shift), amphotericin B, renal tubular acidosis
- EKG signs: Flattened T, prominent U-wave, ST depression
- Symptoms: Weakness, palpitations, polyuria (nephrogenic DI)
- Tx: Oral KCl (20 mEq) or IV if severe/symptomatic (max 20 mEq/hr in peripheral line, 40 mEq/hr in central line to avoid thrombophlebitis)

Calcium (Ca):

Normal (total): 8.5-10.5 mg/dL (ionized 4.5-5.3 mg/dL more accurate, unaffected by albumin)
Hypercalcemia (>10.5): Hyperparathyroidism, malignancy (PTHrP secretion, osteolytic, calcitriol), vitamin D excess, hyperthyroidism, immobilization
- Symptoms: Polyuria, polydipsia, nausea, AMS, “stones, bones, groans, psychiatric overtones”
- EKG: Shortened QT
- Tx: Hydration (saline), loop diuretic (furosemide), bisphosphonate (pamidronate), RANKL inhibitor, treat underlying cause
Hypocalcemia (<8.5): Hypoparathyroidism, vitamin D deficiency, chronic kidney disease, acute pancreatitis, massive transfusion (citrate toxicity), magnesium deficiency
- Symptoms: Paresthesias, tetany, seizures if severe; Chvostek’s sign (tap facial nerve → lip twitch), Trousseau’s sign (inflate BP cuff → hand cramps)
- EKG: Prolonged QT, bradycardia
- Tx: Calcium gluconate 10% IV slow (cardiac monitoring), then chronic supplementation

Chloride (Cl):

Normal: 96-106 mEq/L
Hyperchloremia (>106): Dehydration, hypernatremia, diarrhea (bicarbonate loss)
Hypochloremia (<96): Hyponatremia, diuretics, vomiting, metabolic alkalosis

CO2/Bicarbonate (HCO3):

Normal: 23-29 mEq/L
Elevated: Respiratory acidosis (CO2 retention), metabolic alkalosis
Decreased: Respiratory alkalosis (hyperventilation), metabolic acidosis

Glucose:

Fasting normal: 70-100 mg/dL
Random normal: <140 mg/dL
Impaired fasting: 100-125 mg/dL
Diabetes: Fasting ≥126 mg/dL (confirm with repeat or A1C)

BUN (Blood Urea Nitrogen) & Creatinine (Cr):

Normal BUN: 7-20 mg/dL; Cr: 0.6-1.2 mg/dL
Elevated BUN/Cr (Azotemia): Kidney disease (acute kidney injury-AKI, chronic kidney disease-CKD)
BUN/Cr ratio: High ratio (>20) = prerenal (hypoperfusion: dehydration, sepsis, MI); ratio 10-20 = intrinsic (glomerular, tubular)
Creatinine: More specific for kidney function than BUN (BUN affected by protein intake, dehydration); doubles = 50% loss of GFR
eGFR (estimated glomerular filtration rate): Calculated from Cr, age, gender, race; stages:
- Stage 1: eGFR >90 (normal)
- Stage 2: 60-89 (mild decrease)
- Stage 3a: 45-59 (mild-moderate decrease)
- Stage 3b: 30-44 (moderate-severe decrease)
- Stage 4: 15-29 (severe decrease)
- Stage 5: <15 (kidney failure; dialysis/transplant needed)

Albumin:

Normal: 3.5-5.0 g/dL
Low: Liver disease (cirrhosis), malnutrition, nephrotic syndrome (urinary loss), malignancy
Significance: Reflects nutritional status, affects interpretation of Ca/Mg/bilirubin

Liver Function Tests (LFTs)

AST (Aspartate Aminotransferase) & ALT (Alanine Aminotransferase):

Normal: <40 IU/L
ALT more specific for liver (AST in heart, skeletal muscle, RBC); ALT >AST suggests viral hepatitis, fatty liver; AST >ALT suggests alcoholic liver disease, cirrhosis
Elevated: Acute hepatitis, cirrhosis, liver ischemia (shock, sepsis), autoimmune hepatitis, medications (acetaminophen overdose, statins), hemolysis (spurious)
Pattern: ALT/AST >1000 = acute hepatitis (viral, autoimmune, acetaminophen), ALT/AST 50-300 = cirrhosis, fatty liver, alcohol; minimal elevation = biliary, hemolysis

ALP (Alkaline Phosphatase):

Normal: 30-120 IU/L (higher in children, pregnancy)
Elevated: Biliary obstruction (gallstones, tumors), bone disease (Paget’s, osteomalacia, malignancy with bone mets), pregnancy, adolescence, liver disease
Interpretation: If GGT/ALP elevated, likely hepatic origin; if ALP elevated + GGT normal, likely bone (measure 5’-nucleotidase to differentiate)

GGT (Gamma-glutamyl transferase):

Normal: <55 IU/L
Elevated: Biliary origin of ALP, alcohol use (sensitive marker), medications (phenytoin)

Bilirubin (Total & Indirect):

Normal total: <1.2 mg/dL; indirect: <0.3 mg/dL; direct: <0.3 mg/dL
Hyperbilirubinemia patterns:
- Predominantly indirect (>80% of total): Hemolysis (elevated retic count), Gilbert’s syndrome (benign, mild unconjugated hyperbilirubinemia), impaired conjugation (alcohol, drugs)
- Predominantly direct (>50% of total): Cholestasis (biliary obstruction, intrahepatic cholestasis, pregnancy, drugs), hepatocellular injury (hepatitis, cirrhosis—bilirubin follows ALT/AST)
Clinical signs: Jaundice visible at 2-3 mg/dL; dark urine = elevated conjugated; pale stool = biliary obstruction
Neonatal: Indirect hyperbilirubinemia risk of kernicterus; phototherapy if levels exceed nomogram for age (e.g., >18 mg/dL at 24h)

Albumin & PT/INR:

Albumin reflects synthetic function (low = poor liver function)
PT/INR (prothrombin time) reflects vitamin K-dependent factors (Factors II, VII, IX, X); elevated INR = liver disease, vitamin K deficiency, anticoagulation
Vitamin K deficiency: IV phytonadione (Vitamin K) 10 mg corrects PT in 12-24 hours if nutritional deficiency; if advanced liver disease, transfuse FFP (3-4 units raises INR 0.5-1)

Coagulation Studies

PT/INR (Prothrombin Time):

Normal: 11-13.5 seconds; INR: 0.8-1.1
Measures: Extrinsic pathway (Factors I, II, V, VII, X)
Elevated PT/INR: Warfarin therapy, vitamin K deficiency, liver disease, DIC, lupus anticoagulant
Correction: FFP 10-15 mL/kg (4-6 units) or PCCs (prothrombin complex concentrate, 3-4 factor), vitamin K 5-10 mg IV (takes 12-24h)

aPTT (Activated Partial Thromboplastin Time):

Normal: 25-35 seconds
Measures: Intrinsic pathway (Factors VIII, IX, XI, XII) and common pathway
Elevated: Heparin therapy, deficiency Factor VIII/IX/XI/XII, lupus anticoagulant, DIC, von Willebrand disease
Reversal heparin: Protamine sulfate 1 mg per 100 units heparin IV slow (max 5 mg/min), antihistamines PRN for flushing

Fibrinogen:

Normal: 200-400 mg/dL
Elevated: Acute phase reactant (infection, inflammation, MI, cancer); may mask coagulopathy in early DIC
Decreased: DIC, severe liver disease, afibrinogenemia (genetic), massive transfusion, thrombolytic therapy
Clinical: Fibrinogen <100 = spontaneous bleeding; need replacement (cryoprecipitate 10 units = 1.5 g fibrin)

Platelet Count: See CBC above; <50 = transfuse if bleeding

D-Dimer:

Normal: <0.5 μg/mL (highly variable by lab/assay)
Elevated: VTE (DVT, PE), DIC, sepsis, malignancy, post-operative, myocardial infarction
Use: Very sensitive but low specificity; “rule out” test (negative = low probability VTE); elevated requires imaging confirmation (CTA for PE, ultrasound for DVT)
Don’t order if low pretest probability (just reassure); use in intermediate-high suspicion

Urinalysis

Color:

Normal: pale yellow to amber (depends on concentration)
Dark yellow/amber: Dehydration
Red/brown: RBCs, porphyria, myoglobinuria, beets, medication (rifampin, senna)
Dark brown/black: Alkaptonuria (genetic), acetaminophen overdose, dopa (melanoma), levodopa

Clarity:

Clear: Normal
Cloudy/turbid: WBCs, RBCs, crystals, bacteria, mucus
“Smoky”: RBC casts (glomerulonephritis)

Specific Gravity:

1.005-1.030 normal (1.020-1.030 in dehydration, <1.010 in diabetes insipidus or overhydration)

pH:

4.5-8.0 normal (diet-dependent; acidic = meat diet, alkaline = vegetarian)
Persistently alkaline + foul smell = Proteus infection (struvite crystals = staghorn calculus risk)

Nitrites: Positive = bacteria (gram-negative like E. coli, Klebsiella); negative doesn’t exclude UTI (gram-positive, fastidious organisms negative)

Leukocyte Esterase: Positive = WBCs (sensitivity 75-96%); negative doesn’t exclude WBCs in dilute urine or immune-compromised

Protein:

Negative/trace: Normal (trace OK)
1+ (30 mg/dL): Mild proteinuria; repeat, check 24-hour urine
2+ (100): Moderate; consider kidney disease
3+ (300) or 4+ (>500): Significant; check albumin/globulin ratio, kidney function
Nephrotic syndrome: >3.5 g/day + hypoalbuminemia + edema

Glucose: Absent (renal threshold ~180 mg/dL); present = hyperglycemia or low renal threshold (pregnancy, Fanconi syndrome)

Ketones: Absent; present = DKA, starvation, high-protein diet (metabolic state, not disease severity)

Hemoglobin/Blood: RBC or myoglobin/hemoglobin

1-2 RBC/hpf = normal
3-5 RBC/hpf = hematuria (investigate: kidney stone, glomerulonephritis, malignancy)
Positive dipstick + no RBCs on microscopy = myoglobinuria or hemoglobinuria (rhabdo, hemolysis)

Bilirubin/Urobilinogen:

Bilirubin: Present = cholestasis/hepatocellular disease (conjugated bilirubin excreted)
Urobilinogen elevated: Hemolysis, hepatic disease (can’t take up; recycled), but trace amounts normal

Casts (protein matrix):

RBC casts: Glomerulonephritis (lupus, IgA, ANCA)
WBC casts: Pyelonephritis, interstitial nephritis, glomerulonephritis
Hyaline casts: <2/lpf normal (dehydration, exercise); >2 = kidney stress
Granular casts: Acute tubular necrosis, glomerulonephritis
Fatty casts: Nephrotic syndrome

Crystals:

Calcium oxalate: Risk of kidney stones (dehydration, hyperoxaluria)
Uric acid: Gout, tumor lysis
Struvite (triple phosphate): Proteus infection, alkaline urine, staghorn calculus
Calcium phosphate: Alkaline urine

Cells & Bacteria:

<5 WBC/hpf normal; >5 = pyuria (UTI, contamination, glomerulonephritis)
<1 RBC/hpf normal; >5 = hematuria
Bacteria present = bacteriuria; if WBCs + symptoms = UTI; if bacteria only = asymptomatic bacteriuria (don’t treat in most except pregnant women, urologic procedures)
Epithelial cells: Few normal (catheterized); many = contamination

Blood Gases & Acid-Base

Arterial Blood Gas (ABG):

Normal: pH 7.35-7.45, PaCO2 35-45 mmHg, PaO2 80-100 mmHg (decreases with age: 100 - age/4), HCO3 22-26 mEq/L, SaO2 >95%

Step-by-Step Interpretation:

Check pH: <7.35 = acidemia, >7.45 = alkalemia
Check PaCO2 & HCO3:
- If pH down + PaCO2 up + HCO3 down → Respiratory acidosis (with renal response)
- If pH down + HCO3 down + PaCO2 low = Metabolic acidosis (respiratory compensation)
- If pH up + HCO3 up = Metabolic alkalosis
- If pH up + PaCO2 down = Respiratory alkalosis
Check appropriateness of compensation:
- Winter’s formula (respiratory response to metabolic acidosis): PaCO2 = 1.5[HCO3] + (8 ± 2)
- Metabolic response: 3-4 mEq/L HCO3 change per 10 mmHg PaCO2 change (acute) or 5-7 mEq/L (chronic)

Metabolic Acidosis (HCO3 <22, pH <7.35):

High anion gap (>12): Lactic acid (sepsis, shock, hypoxia), ketoacids (DKA, alcoholic ketoacidosis), uremia, toxins (methanol, ethylene glycol, salicylates)—mnemonic LAKD
Normal anion gap (hyperchloremic): Diarrhea (bicarbonate loss), renal tubular acidosis, medications (acetazolamide), ureteral diversions
Treatment: Address underlying cause; sodium bicarbonate if severe (pH <7.1) or hemodynamically unstable; titrate to pH >7.20

Metabolic Alkalosis (HCO3 >26, pH >7.45):

Causes: Vomiting (H+ loss), diuretics (contraction alkalosis), hypokalemia, alkali ingestion
Saline-responsive: Dehydration, vomiting; treat with normal saline, potassium replacement
Saline-resistant: Primary hyperaldosteronism, Cushing syndrome; treat underlying, potassium-sparing agents
Treatment: If pH <7.55, usually tolerated; if severe: acetazolamide (causes bicarb wasting), HCl in severe (use in critical care only), address hypokalemia

Respiratory Acidosis (PaCO2 >45, pH <7.35):

Causes: Decreased minute ventilation (sedation, narcotics, hypoventilation), increased CO2 production (fever, exercise), airway obstruction
Acute (minutes-hours): pH drops ~0.08 per 10 mmHg PaCO2 rise
Chronic (days): Kidney compensation; HCO3 rises ~3-4 mEq/L per 10 mmHg PaCO2 rise
Treatment: Improve ventilation (oxygen, BVM, intubation); monitor closely

Respiratory Alkalosis (PaCO2 <35, pH >7.45):

Causes: Hyperventilation (anxiety, pain, hypoxia, PE, fever, aspirin overdose), mechanical ventilation set too high
Treatment: Identify cause; anxiolytics if anxiety; if mechanical ventilation, reduce rate; monitor for hypokalemia

Oxygenation:

PaO2 <60 mmHg: Hypoxemia; give oxygen
A-a gradient (alveolar-arterial): Normal <10; elevated suggests lung pathology
- Calculate: PAO2 = FiO2(760 - 47) - (PaCO2/0.8)
- A-a = PAO2 - PaO2
- Elevated = V/Q mismatch (pneumonia, atelectasis, PE), shunt (intracardiac defect), diffusion impairment (ARDS, pulmonary fibrosis)

Blood Typing & Crossmatch

ABO Blood Group:

Type O: No A/B antigens; anti-A & anti-B antibodies (universal donor RBCs, universal recipient plasma)
Type A: A antigen; anti-B antibodies
Type B: B antigen; anti-A antibodies
Type AB: A & B antigens; no anti-A/B (universal recipient, rare donor)

Rh Factor:

Rh+ (D antigen present): 85% population
Rh- (no D): 15%; develops anti-D if exposed to Rh+ blood (hemolytic transfusion reaction if re-exposed)
Rh- women: Give RhoGAM (anti-D immune globulin) 300 mcg (100 IU/kg) IM within 72h of:
- Delivery of Rh+ baby
- Miscarriage/abortion >12 weeks
- Amniocentesis, chorionic villus sampling
- Antepartum hemorrhage

Crossmatch:

Type & Screen: ABO/Rh + antibody screen (detects clinically significant antibodies)
Full Crossmatch: Type & screen + major crossmatch (patient serum + donor RBCs) + minor crossmatch (patient RBCs + donor serum)
Computer Crossmatch: Electronic verification without wet crossmatch if negative antibody screen + repeat ABO/Rh
Time: Type & screen 10-15 min; full crossmatch 30-45 min; uncrossmatched O neg 5 min (emergency only)

Transfusion Reactions:

Acute hemolytic (minutes-hours): ABO incompatibility (wrong blood type); fever, chest pain, hemoglobinuria, shock, DIC
- Stop transfusion immediately, keep IV patent, send blood for repeat type/crossmatch, urinalysis (hemoglobinuria), check renal function, monitor urine output
- Tx: Aggressive hydration (maintain urine output >200 mL/hr), diuretics if volume overload, dopamine if renal vasoconstriction, manage shock/DIC
Febrile non-hemolytic (minutes to 12h): Leukocyte contamination; fever, chills, mild tachycardia
- Tx: Acetaminophen, diphenhydramine; leuko-reduce future units
Allergic (minutes to hours): Proteins in donor plasma; urticaria, pruritus, angioedema
- Mild (urticaria): Pause, give antihistamine, restart if resolves; if severe → steroids, epinephrine
Anaphylactic (seconds to minutes): IgA deficiency in recipient develops anti-IgA; hypotension, bronchospasm, airway edema
- Rare; requires IgA-free/washed RBCs for future transfusions
TRALI (Transfusion-Related Acute Lung Injury): Immune attack on lungs; pulmonary edema, hypoxemia, fever; appear 1-2h post-transfusion
- Tx: Supportive (O2, may need intubation), diuretics with caution (noncardiogenic pulmonary edema)
Volume overload: Congestive pulmonary edema if transfused too fast (especially elderly, renal disease)
- Tx: Diuretics, slow infusion rate (<2 mL/min in high-risk)
GVHD (Graft-versus-Host Disease): Engrafted donor lymphocytes attack recipient; fever, rash, diarrhea, LFT elevation; may be fatal
- Prevention: Irradiate products for immunocompromised recipients

Massive Transfusion Protocol (>4 units PRBC in 1 hour or >10 units in 24h):

Problem: Dilutional coagulopathy, thrombocytopenia, hypothermia, acidosis, hypocalcemia (citrate toxicity)
Ratios: 1 PRBC : 1 FFP : 1 platelets (1:1:1 ratio) or PRBC : FFP : platelets 2:1:1 (depends on protocol)
Monitoring: CBC, PT/INR, fibrinogen, lactate q4h
Adjuncts: Tranexamic acid (TXA) 1 g IV bolus within 3h of injury (if bleeding expected to continue); massive transfusion reversal agents (andexanet alfa for Xa inhibitors, idarucizumab for dabigatran)
Prevention of complications: Warm IV fluids, limit lactated Ringer’s (citrate load), monitor potassium, calcium

Emergency Transfusion (>5 min to crossmatch unavailable):

Type O Rh- uncrossmatched blood (lowest risk)
Once type known, switch to O matched
Full crossmatch when available

Walking Blood Bank (small clinic/resource-limited setting):

Recruit family members as donors; screen for ABO/Rh + basic serology in advance
No full crossmatch time for emergency
Risks: Limited donor pool, may have incompatible antibodies, variable donor quality
Best for massive hemorrhage (obstetric, trauma) with no blood bank access

3. MICROSCOPY

Light Microscope Use

Components:

Objective lenses: 4x (scanning), 10x (low power), 40x (high power), 100x (oil immersion)
Eyepiece: 10x magnification
Total magnification: Objective × Eyepiece (e.g., 40 × 10 = 400x)
Condenser: Focuses light; adjust aperture for contrast
Coarse/fine focus: Coarse for initial focus, fine for detail
Oil immersion: 100x requires immersion oil; increases refractive index; improves resolution

Procedure:

Start at 4x, locate specimen, focus with coarse knob
Move to 10x, fine focus, adjust condenser
Move to 40x, fine focus, adjust light/condenser (reduced aperture = contrast, dark background)
For 100x: Place small drop immersion oil on slide, rotate objective to 100x, use fine focus only (oil acts as lens medium)
Before leaving: Remove oil with lens paper + xylene, wipe objectives, return to low power

Maintenance:

Clean lenses immediately after use (oil immersion especially)
Use lens paper only, never cloth (scratches)
Keep dust covers on when not in use
Oil → xylene (cleaner) → lens paper
Protect from moisture; store in dry cabinet

Peripheral Blood Smear

Preparation:

Place drop of fresh blood on frosted end of slide
Using second slide at 45° angle, pull drop across (thin film, feathered edge)
Air-dry (don’t heat-fix, allows better staining)
Wright-Giemsa stain 1 min, rinse, dry

Examination (100x oil immersion):

Scan low power (40x) for even distribution, artifacts
At 100x: RBCs should be evenly distributed, not overlapping
Count WBC differential: 100-count method (count 100 WBCs, % of each type)

RBC Morphology:

Normal: 6-8 μm diameter, pale center, regular shape
Microcytic: <6 μm (iron deficiency, thalassemia)
Macrocytic: >8 μm (B12/folate deficiency, reticulocytes)
Hypochromic: Large pale area (iron deficiency)
Polychromasia: Blue-gray tint (immature RBCs/reticulocytes)
Anisopoikilocytosis: Variation in size/shape (poor prognosis sign in severe disease)
Target cells: Spiculated appearance (thalassemia, liver disease, SIADH from membrane excess)
Schistocytes: Fragmented RBCs; “helmet cells” (DIC, TTP, hemolytic anemia)
Spherocytes: Small, dark, no pale center (hereditary spherocytosis, autoimmune hemolytic anemia)
Sickle cells: Crescent shape (sickle cell disease)
Rouleaux: Stacked like coins (hyperglobulinemia, inflammation)

WBC Morphology:

Neutrophils: Large nucleus, multilobed (3-5 lobes), cytoplasm pale, fine granules
Left shift: Increased bands (immature); each level of immaturity (band → metamyelocyte → myelocyte) = infection/stress
Toxic granulations: Dark coarse granules (sepsis)
Dohle bodies: Cytoplasmic inclusions (sepsis, MDS)
Lymphocytes: Small, dark nucleus, scant cytoplasm; activated = larger, more cytoplasm, blue tint
Atypical lymphocytes: Seen in viral infection (EBV, CMV)
Monocytes: Larger, kidney-bean nucleus, abundant cytoplasm with vacuoles, pseudo-pods
Eosinophils: Bilobed nucleus, large orange-red granules (40x may suffice to count)
Basophils: Bilobed, large dark granules that often obscure nucleus

Platelet Estimate:

~8-10 platelets per hpf (100x) ≈ normal count 150-400k
<2/hpf = thrombocytopenia
25/hpf = thrombocytosis

Malaria Smears

Thick Smear (screening, parasite concentration):

20 μL blood on slide, spread to cover ~1 inch circle
Don’t air-dry fully; stain while slightly wet with Giemsa or Wright-Giemsa
Hemoglobin lysis; parasites visible against background debris
Parasite count: Present? (positive/negative); estimate parasitemia if positive (count parasites in 8 fields, average, multiply by RBC count from CBC)

Thin Smear (species identification, morphology):

Same as peripheral blood smear
Individual RBCs allow detailed parasite morphology
Gram: P. falciparum = ring forms + marophages (“signet ring”), rosetting, accoles; P. vivax = stippled RBCs, larger parasites; P. ovale = fimbriated (jagged) RBCs; P. malariae = band-form trophozoite

Examination:

Screen thick smear 40x, use 100x oil for species ID on thin smear
Count gametocytes (gametes = sexual stage; presence = transmissible)
Report: Species, %parasitemia, asexual vs gametocytes

Interpretation:

<0.1% parasitemia = low
0.1-1% = low-moderate
1-5% = moderate
5% = high (severe malaria risk: cerebral, pulmonary edema, severe anemia)

Urine Microscopy

Centrifugation: Spin 450 mL urine at 450g x 5 min; discard supernatant, resuspend in 50 mL; prepare wet mount from concentrate

WBC & RBC:

Normal: <5 WBC/hpf, <3 RBC/hpf
Increased WBC = infection (UTI, pyelonephritis), glomerulonephritis, contamination
Increased RBC = hematuria; work-up for kidney stones, glomerulonephritis, malignancy

Casts (see urinalysis above; quantify):

<2 hyaline casts/lpf = OK
RBC casts = glomerulonephritis (always abnormal)
WBC casts = pyelonephritis, interstitial nephritis

Crystals (see urinalysis; mention in report if abundant)

Bacteria: Rod-shaped; spirals (Spirillum); cocci. If >1 bacterium/hpf, consider UTI; if no WBCs, likely contamination

Yeast: Round, budding forms; usually Candida (vaginal contamination vs. UTI if catheterized; immunocompromised at risk)

Stool Microscopy

Parasites:

Ova: Eggs visible; hookworm (embryonated), roundworm (large), whipworm (barrel-shaped), tapeworm (proglottids)
Trophozoites: Motile organisms (E. histolytica shows RBC ingestion = pathogenic; E. dispar nonpathogenic)
Cysts: Dormant stages; E. histolytica 4 nuclei, Giardia 4 nuclei, Cryptosporidium small 4-6 μm
Sample: Stool in container; if looking for motile trophozoites, examine warm within 20 min (cool = die/encyst)
Concentration methods: Formaldehyde-ether (helminth eggs), iodine staining (protozoan cysts)

Leukocytes: Indicate inflammation; PMNs suggest bacterial infection (invasive), lymphocytes viral/inflammatory

Gram Stain Procedure

Preparation:

Specimen on glass slide (sputum, urine, wound, CSF—centrifuge)
Smear thin layer, air-dry, heat-fix (pass 3x through flame)

Staining:

Crystal violet 1 min (all cells purple)
Gram’s iodine 1 min (mordant; all cells dark purple)
Acetone-alcohol 10-30 sec (decolorizer; gram-negative cells lose color, gram-positive retain)
Safranin 1 min (counterstain; gram-negative cells become pink/red)

Result:

Gram-positive: Purple (thick peptidoglycan layer; absorbs dyes)
Gram-negative: Pink/red (thin peptidoglycan; outer membrane lipopolysaccharide)

Morphology:

Cocci: Streptococcus (chains), Staphylococcus (clusters), Neisseria (gram-negative diplococci “kidney bean” shape), Pneumococcus (gram-positive diplococci lancet-shaped)
Rods: Bacillus (gram-positive, spores), Clostridium (gram-positive, spores), E. coli (gram-negative), Pseudomonas (gram-negative, thin)
Gram-positive rods with spores: Bacillus/Clostridium (differ by motility, spore location)

Intracellular bacteria: Gonorrhea (intracellular in PMNs), meningococcal (intracellular diplococci in CSF)

KOH Prep (Fungal Preparation)

Procedure:

Specimen (skin scraping, nail, hair) on slide
Add 1-2 drops 10-40% KOH
Cover with coverslip, gently heat (not boiling; softens keratinized material)
Examine 40x for fungal elements

Findings:

Dermatophytes: Branching septate hyphae (rod-like); spores (round bodies)
Candida: Yeast (round, budding) + pseudohyphae (chains of elongated cells)
Tinea versicolor (Malassezia): “Spaghetti and meatballs” (hyphae + yeast clusters)

Wet Mount

Procedure:

Specimen in drop normal saline on slide
Place coverslip; examine immediately (before drying)

Uses:

Urine: See crystals, WBC, bacteria mobility (if motile → E. coli; non-motile cocci)
Vaginal: Trichomonas (motile, flagellated pear shape), Candida (pseudohyphae budding yeast), bacteria (BV clue cells = epithelial cells with bacteria coating edges)
Stool: Motile trophozoites (E. histolytica = RBC ingestion), Giardia (leaf-shaped), Cryptosporidium (use oocyst stain instead)
CSF: WBC count, morphology (PMN = bacterial, lymph = viral/TB), RBCs (bleeding vs. contamination)

AFB Smear (Acid-Fast Bacillus, Tuberculosis)

Procedure:

Specimen (sputum, CSF, tissue homogenate) smear on slide, heat-fix
Ziehl-Neelsen stain:
1. Carbol fuchsin heat 5 min (bacilli red)
2. Acid-alcohol 20 sec (decolorizer; AFB retain, others lose color)
3. Methylene blue counterstain 1 min (non-AFB blue)
Result: Red rods on blue background = TB+ (or atypical mycobacteria)

Alternative: Auramine-O fluorescent stain (bacilli fluoresce yellow-green under UV); more sensitive but requires fluorescence microscope

Reporting:

Negative: <1 AFB per 100 fields (scanty, 1-9 AFB per 100 fields, 10-99 per field, >100 per field)
Smear-positive = infectious TB
Culture confirms (2-8 weeks for Mycobacterium tuberculosis)

4. IMAGING INTERPRETATION

Systematic Chest X-Ray (ABCDE Method)

A: Airway/Alignment

Trachea: Midline, no deviation (tension pneumothorax shifts trachea away from collapsed side)
Mediastinum: Center between lungs, not widened (widening >6 cm suggests mediastinitis, aortic dissection)
Heart: <50% of chest width (cardiomegaly if >50%; may be magnified if portable film—note distance)

B: Bones

Ribs, clavicles, scapulae, vertebrae: Fractures, lytic/sclerotic lesions (metastatic disease)
Rib notching: Hyperparathyroidism, neurofibromatosis, connective tissue disease
Osteopenia: Chronic illness, steroid use

C: Cardiac Silhouette

Enlarged (cardiomegaly): CHF, cardiomyopathy, valvular disease, pericardial effusion
Configuration: Mitral stenosis (straightened left heart border “hockey stick”); aortic disease (widened mediastinum)
Pulmonary vasculature: Cephalization (upper lobe vessels dilated >lower lobes) = CHF; peripheral pruning (upper lobe spared) = COPD, primary hypertension

D: Diaphragm

Symmetric, peaked apices (normal)
Flattening: COPD, asthma (airtrapping)
Elevation: Pleural effusion (splinting), atelectasis, diaphragm paralysis
Silhouette sign: Loss of normal border = adjacent consolidation/mass
- Silhouette right heart border + consolidation = right middle lobe pneumonia
- Silhouette left heart = left lower lobe

E: Extrapulmonary & Parenchymal

Pneumonia:

Typical: Lobar consolidation (dense infiltrate respecting lobe boundaries); air bronchograms (black branches = aerated bronchi in solid tissue)
Atypical: Interstitial (perihilar) infiltrates, “viral pneumonia” appearance
Complications: Pleural effusion, empyema (fluid with internal debris), abscess (air-fluid level)

Pneumothorax:

Signs: Visceral pleura visible (thin white line); lucent lung peripherally; mediastinal shift if tension (trachea deviated away)
Primary spontaneous: Young, tall males (bullae rupture); secondary = COPD, cystic fibrosis, sarcoidosis
Tension: Hemodynamic collapse; tracheal deviation, hypotension, hypoxemia → needle decompression 2nd ICS midclavicular

Pleural Effusion:

Small: Blunting of costophrenic angle (normally sharp 45° angle)
Moderate-large: Opacification of lower portion; mediastinal shift if unilateral
Bilateral: Suggests CHF (symmetric); if asymmetric consider malignancy, PE, pneumonia
Characteristics: Transudative (CHF, cirrhosis, nephrotic syndrome—protein <30 g/L, LDH <200) vs. exudative (pneumonia, PE, malignancy, pericarditis—protein >30 g/L)
Layering: On lateral decubitus film = free fluid; loculated = trapped in adhesions

Atelectasis:

Lobar: Lobe collapses toward hilum; translucent (denser than normal lung); mediastinal shift toward collapsed side
Causes: Mucus plug, foreign body, central tumor, external compression
Risk: Post-operative, immobility, intubation; treat with cough, incentive spirometry, suctioning

Pulmonary Edema:

Interstitial: “Bat wing” cephalization (fluid upper lobes due to upright position increasing hydrostatic pressure upper vessels)
Alveolar: White-out appearance, air bronchograms; Kerley B lines (horizontal lines at lung bases = septal edema)
Causes: Cardiogenic (elevated PCWP from CHF, MR, aortic regurgitation) vs. noncardiogenic (sepsis, ARDS, toxins, reperfusion)

COPD Changes:

Hyperinflation: Flattened diaphragms, increased retrosternal air space, barrel-shaped chest
Bullae: Large air-filled blebs; rupture = pneumothorax
Bronchitis: Bronchial wall thickening “tram-track” appearance

Pneumonia Patterns:

RUL: Right upper lobe (superior segment = apical), right middle lobe (horizontal fissure), right lower lobe (posterior basal best seen on lateral)
LUL: Left upper lobe (lingula + superior lobes), left lower lobe
Aspiration: RML (supine patients), LLL common if upright (position + gravity)

Abdominal X-Ray

Three Classic Signs:

Pneumoperitoneum (free air): Black crescent under diaphragm on upright CXR or “rigler sign” (pneumatosis) on flat film; indicates perforation (peptic ulcer, diverticulitis, appendicitis with rupture)
Bowel Obstruction: Dilated bowel loops (>3 cm small bowel, >6 cm colon), air-fluid levels on upright film (step-ladder appearance); haustra preserved in colon (partial obstruction) vs. lost (closed loop)
- Small bowel obstruction: Central, valvulae coniventes cross entire width, 3-5 cm diameter
- Large bowel obstruction: Peripheral, haustra, 6 cm diameter (risk of perforation >12 cm)
- Causes: Adhesions post-surgery, hernia, volvulus (twisted bowel; sigmoidal “bird-beak” sign), intussusception (telescoping; “target” sign on CT)
Ileus: Diffuse dilation of bowel without mechanical obstruction; may be nonspecific (post-operative, peritonitis, electrolyte, medications)

Volvulus:

Sigmoid: Elderly, chronic constipation; “bird-beak” transition, excessively dilated sigmoid (may reach >15 cm)
Cecal/small bowel: Younger patients with adhesions or malrotation; toxic megacolon if ischemic
Treatment: Rectal tube (sigmoidoscopy deflation), surgery if ischemia/perforation

Fecal Impaction:

Massive stool burden; constipation; may develop cecal perforation (Ogilvie syndrome = pseudoobstruction)

Appendicitis:

May show focal RLQ lucency (free air from rupture), sentinel loop (dilated small bowel loop near appendix), fecalith (opaque density in RLQ); insensitive—CT/ultrasound preferred

Renal Colic:

May show stone (if calcified); most stones lucent (uric acid, calcium oxalate may be visible); CT non-contrast gold standard

Extremity X-Rays (Fractures & Dislocations)

Fracture Characteristics:

Displacement: Angulation (bent), shortening, rotation, lateral translation
Comminution: Multiple fragments (worse prognosis, harder to reduce)
Alignment: Amount of angulation in degrees
Involvement: Intra-articular (within joint space—high complication risk) vs. extra-articular

Common Patterns:

Colles fracture: Dorsal displacement of distal radius; “dinner fork” deformity; classic wrist injury from fall on outstretched hand (FOOSH)
Smith fracture: Volar displacement distal radius; opposite mechanism (fall with flexed wrist)
Anterior shoulder dislocation: 95% of dislocations; “light bulb sign” on AP view (humeral head appears round/unrotated); X-ray postreduction ensures reduction
Posterior hip dislocation: Associated with hip flexion trauma (dashboard injuries, seizures); Shenton line disrupted (line along femoral neck); risks avascular necrosis
Posterior knee dislocation: Rare; high risk of popliteal artery injury; assess pulses, consider angiography

Stress Fractures:

Fine fracture line through bone, often subtle early
Risk: Overuse, osteoporosis, female athlete triad (amenorrhea, eating disorder, osteoporosis)
Sites: Tibia (runners), femoral neck (elderly women), metatarsals (dancers), ribs (cough)
Treatment: Rest, no weight-bearing until healing (6-8 weeks)

Salter-Harris Classification (pediatric growth plate fractures):

Type I: Transverse through growth plate (best prognosis)
Type II: Through growth plate + metaphysis (“Salter II”; most common)
Type III: Through growth plate + epiphysis (joint involvement)
Type IV: Through all (worst prognosis; risk of growth arrest)
Type V: Crush of growth plate (latent growth disturbance)

FAST Ultrasound (See above under Ultrasound Basics)

Basic POCUS (See above under Ultrasound Basics)

5. EQUIPMENT MAINTENANCE

Autoclave Operation

Principle: Saturated steam at 121°C for 15-30 minutes kills spores (most resistant microorganisms)

Pre-autoclave Preparation:

Clean instruments immediately (don’t let blood/body fluid dry; denatured proteins prevent steam penetration)
Disassemble hinged instruments, open scissors fully
Wrap in single-layer surgical cloth (double wrap delays steam penetration to core)
Use chemical indicators (color-change strips inside packs) to confirm steam exposure
Don’t overload chamber (blocks steam circulation)

Autoclave Settings:

Unwrapped items: 121°C, 15 psi, 15 minutes (tableware, instruments for immediate use)
Wrapped items: 121°C, 15 psi, 30 minutes (packs for storage)
High-altitude (>1500 m): Increase pressure/time (steam pressure lower due to atmospheric pressure)

Biological Indicators:

Spore tests (Bacillus stearothermophilus); run monthly
Incubate 24-48h; no growth = sterilization successful

Post-Autoclave:

Allow wrapped packs to cool; moisture absorption indicates cooling (wrapping prevents contamination during cooling)
Store in clean, dry space; expiration 3-6 months (depends on storage conditions; if wet/exposed, resterilize)
Inspect for integrity before use; open packs = resterilize

Sterilization Protocols & Alternatives

Chemical Sterilization (non-autoclavable items: flexible endoscopes, electronics):

Glutaraldehyde 2%: 3h high-level disinfection; requires proper ventilation (irritant), minimum 50 items/liter solution
Peracetic acid: Faster (<1h); same effectiveness as glutaraldehyde; automated washers available
Flash sterilization: 3-6 min at 132°C (unwrapped items, immediate use); NOT for implants (risk of retained moisture → corrosion)

High-Level Disinfection (for semicritical items: biopsy forceps, bronchoscopes):

Glutaraldehyde/peracetic acid for 20-45 min (kills most microorganisms but not necessarily spores)
Adequate for instruments contacting mucous membrane but not sterile sites

Low-Level Disinfection (noncritical items: stethoscope, BP cuff):

70% isopropyl alcohol, 0.5% hypochlorite solution
Wipe surfaces; adequate for contamination with blood/body fluids

Generator Maintenance (Hospitals, Resource-Limited Settings)

Monthly:

Check fuel level; top up (diesel generators; don’t allow to run dry or completely full)
Inspect for leaks (fuel, oil, coolant)
Check battery terminals (corrosion); test voltage ~12 V
Start generator under load; listen for abnormal sounds, check exhaust

Quarterly:

Change oil filter (if applicable; check manufacturer intervals)
Drain condensation from fuel tank (water accumulation causes bacterial growth, fuel contamination)
Test automatic transfer switch (ATS; switches power when mains fails)

Annually:

Full load test (run at 75% rated capacity, 2h minimum)
Coolant fluid analysis (check pH, contamination)
Partial replacement/top-up of coolant (if hot climate)
Inspect belts, hoses for cracks

Storage (if not regularly used):

Run monthly to charge battery, circulate oil/coolant, prevent fuel degradation
Maintain fuel stabilizer if long-term storage (6+ months)
Store indoors, cover to prevent corrosion

Cold Chain Management (Vaccines, Blood Products)

Temperature Requirements:

Vaccines: 2-8°C (refrigerator); tolerance for excursions <30°C <48h but avoid freezing (kills potency)
Blood bank: RBCs 1-6°C (fridge), plasma -18°C or colder (freezer), platelets 20-24°C (room temp), cryoprecipitate -18°C
Loss of potency: Freeze-thaw = loss (RBCs hemolyzed; plasma protein precipitation), overheating = inactivation (vaccines, some biologics)

Monitoring:

Digital thermometer/data logger (records temp q30min) preferred over mercury
Inspect fridge/freezer daily for temperature alarm, frost accumulation, door seals
Stock monitoring: FIFO (first-in, first-out); remove expired items monthly
Power failures: Keep fridge/freezer door closed (maintains cold x4-6h if undisturbed)

Contingency:

Backup generator or power supply UPS (uninterruptible power supply)
Insulated transport boxes for vaccine clinics; pre-chill with ice packs
Discard vaccines if frozen; RBCs if frozen accidentally (hemolyzed upon thawing)

Improvised Equipment (Resource-Limited Settings)

Makeshift Splints:

Newspaper/cardboard: Rolled newspaper, secured with cloth strips; adequate for arm/lower leg
Bamboo: Flat bamboo strips with cloth wrapping; supports weight
Inflatable splint: Emergency room: clear plastic wrap inflated with air (IV tubing)
Proper splinting: Immobilize joint above/below fracture, pad bony prominences (prevent pressure sores), neurovascular checks (distal pulses, sensation)

Cervical Collar (C-spine):

Rolled newspaper/foam padding around neck + cloth tape; prevents flexion/extension
Inspect Q1h for pressure points, skin breakdown

Traction (femur fracture):

Thomas splint: Wooden frame with sling suspension; patient’s body weight = counter-traction
Skin traction: Adhesive strips (Buck’s) + weights (5-7 lbs for femur) hanging off bed edge
Alternative: Thomas traction-splint (field expedient); alignment + pain control

Chest Seal (sucking chest wound/penetrating trauma):

Three-sided tape/dressing: Cover wound on 3 sides, leave 1 side open (flutter valve for air escape)
Commercial: Asherman chest seal if available
Goal: Prevent air entry (convert open to closed pneumothorax) while allowing air/blood egress (prevent tension physiology)
Definitive: Tube thoracostomy (chest tube), surgical exploration if massive/cardiac/mediastinal involvement

Improvised Suction:

Hand-crank pump: Mechanical suction device (old medical equipment still available)
Ambu bag-powered: Attach to Ambu valve → negative pressure during release
Gravity/siphon: Draw negative pressure with syringe, clamp tubing (limited, unreliable)
Alternatives: Bulb syringe, French catheter + manual aspiration (limited power)

Water Purification for Medical Use

Boiling:

1 minute rolling boil kills most pathogens; 3 minutes at higher altitudes
Ineffective for chemical contaminants; cumbersome for large volumes

Chlorination:

Household bleach (5-6% sodium hypochlorite): 1-2 drops per liter clear water, 30 min contact time (cloudiness requires pre-filtering/pre-treatment)
Chlorine tablets: Pre-measured; same principle
Risk: Organochlorine formation (potential carcinogen) with long-term use; taste/smell (unpalatable long-term)

Filtration:

Sand filtration: Layers of sand, gravel; removes suspended particles, some bacteria; ineffective for viruses
Activated charcoal: Removes chemical contaminants, chlorine, taste/odor
Membrane filtration: 0.2 μm microbial filter removes bacteria/protozoa (viruses may pass)
Reverse osmosis: High pressure forces water through semipermeable membrane; removes salts, viruses, bacteria; slow; produces waste water (3:1 waste to product)

Boiling + Filtration:

Most practical in resource-limited: Boil to kill microbes, then filter through sand/cloth to remove particulates/recolonization

For Medical Use (sterile water):

Distillation: Boil water, collect steam condensate (pure H2O, removes all impurities); labor-intensive but effective
Acceptable for most purposes: Boiled + filtered + stored in clean, sealed containers
IV fluids: Pre-manufactured or compounded in lab with filtration/autoclaving (field setting: avoid; risk of pyrogenic reactions)

6. BLOOD BANK

Blood Typing (ABO/Rh System)

ABO Blood Groups (Landsteiner’s Law):

Type O: No A/B antigens on RBCs; plasma has anti-A & anti-B IgM antibodies (naturally occurring)
- Transfuse to: Any ABO type (universal RBC donor)
- Can receive: Type O only
Type A: A antigen on RBCs; plasma has anti-B antibodies
- Transfuse to: Type A & AB
- Can receive: Type O & A
Type B: B antigen on RBCs; plasma has anti-A antibodies
- Transfuse to: Type B & AB
- Can receive: Type O & B
Type AB: A & B antigens; no anti-A/B antibodies
- Transfuse to: Type AB only (universal recipient RBCs)
- Can receive: All types (universal recipient)

Rh System (30+ antigens; D most immunogenic):

Rh+: D antigen present; IgG naturally absent (sensitization requires exposure)
Rh-: No D; will develop anti-D (hemolytic transfusion reaction if re-exposed to Rh+ blood)
Weak D phenotype (Del): Rare variant; small amount D antigen; type as Rh+ for transfusion purposes

Typing Method:

Slide/tube agglutination: Add patient serum + RBCs to antisera (anti-A, anti-B, anti-D)
- Agglutination (clumping) = positive
- No clumping = negative
Crossover check: Reverse typing (patient RBCs + type-known plasma confirms ABO); discrepancy = error or rare antigen

Crossmatch Procedures

Type & Screen:

ABO/Rh typing: Confirms blood type
Antibody screen: Patient serum incubated with panel of RBCs with known antigens (detects clinically significant alloantibodies: anti-Kell, anti-Duffy, etc.)
Time: 10-15 min; if negative, blood has low incompatibility risk

Major Crossmatch:

Purpose: Ensure donor blood compatible with recipient plasma antibodies
Method: Patient serum + donor RBCs; agglutination = incompatible (don’t transfuse)
Time: 30-45 min (includes Coombs phase—enhanced detection)
Interpretation:
- Negative = safe to transfuse
- Positive (1-4+ agglutination strength) = incompatible; find alternate unit

Minor Crossmatch:

Purpose: Ensure donor plasma (FFP, whole blood) compatible with recipient RBCs (rarely performed now due to FFP volume dilution)
Method: Donor serum + recipient RBCs
Significance: Low clinical relevance (donor antibodies diluted in recipient circulation)

Computer Crossmatch (Electronic Verification):

Requirements: Type & screen negative + repeat ABO/Rh confirmation + no recent transfusion
Process: Computer verifies unit D antigen/ABO match with patient type
Advantages: Faster (5-10 min), reduced manual error
Cannot use if: Positive antibody screen, patient has unusual antibodies, recent transfusion

Component Storage & Shelf Life

RBCs (packed RBCs, PRBC):

Additive solution (CPD-A): 42 days at 1-6°C
Preservative (CPDA, CP2D): Up to 42 days (adenine maintains ATP, energy for RBC viability)
Storage: Refrigerated, continuous agitation (prevents hemolysis, RBC clumping)
Volume: 250 mL concentrate (hematocrit ~70%)
Effect: 1 unit = increase Hgb ~1 g/dL in 70 kg adult

Fresh Frozen Plasma (FFP):

Shelf life: 1 year frozen at -18°C or colder; 24 hours once thawed at room temp
Volume: 200-250 mL per unit
Composition: All coagulation factors, albumin, immunoglobulins
Indication: Coagulopathy with elevated INR (liver disease, anticoagulation reversal), deficiency of multiple clotting factors
Dose: 10-15 mL/kg (usually 2-4 units in adult) to raise factor levels ~20%
Note: Slow infusion (over 15-30 min per unit); contains fibrinogen, not suitable for isolated fibrinogen deficiency (use cryoprecipitate)

Platelets:

Shelf life: 5-7 days at 20-24°C (room temperature) with continuous gentle agitation
Storage: Room temp increases bacterial contamination risk; some centers use pathogen reduction
Volume: 40-50 mL per unit; ~5-7 × 10^10 platelets
Indication: Thrombocytopenia with bleeding or count <10-20k (prophylactic transfusion)
Dose: 1 unit per 10 kg body weight (typically 6 units = 1 “six-pack”)
Refractoriness: Alloimmunization; use HPA-matched platelets or cross-matched

Cryoprecipitate (“Cryo”):

Shelf life: 1 year frozen; 6 hours once thawed
Volume: 10-15 mL per unit
Composition: Fibrinogen (80-100 mg), Factor VIII (80 units), Fibronectin, von Willebrand factor, Factor XIII
Indication: Hypofibrinogenemia (<100 mg/dL), DIC with low fibrinogen, massive transfusion
Dose: 1 unit per 5-10 kg (10 units typical adult dose raises fibrinogen ~60-100 mg/dL)
Advantage over FFP: Concentrated; minimal volume expansion

Whole Blood:

Storage: 21-42 days depending on anticoagulant (CPD vs. CPDA)
Use: Rare (component therapy more efficient); massive hemorrhage if unavailable
Advantage: 1:1:1 ratio RBC:plasma:platelets approximates blood composition
Disadvantage: Platelet viability decreases (stored at cold temps), risk higher infection transmission, incompatible antibodies in plasma

Transfusion Protocols & Monitoring

Pre-Transfusion:

Verify patient identity (2 identifiers; arm band vs. verbal vs. blood bank number)
Verify blood type/unit number with patient label
Assess IV access (18-20G preferred for rapid infusion; 22G acceptable)
Record baseline vital signs, Hgb

Transfusion Process:

Inspect unit: Discard if clots, gas bubbles, hemolysis (dark purple), leaks, expiration passed
Administer through blood warmer if massive transfusion (prevent hypothermia + hemolysis)
Initial rate: Slow first 15 min (monitor for transfusion reaction); increase if tolerated
Monitor every 15 min: Vital signs, urine output (hemoglobinuria if reaction), hemolysis signs
Infuse at least 1 unit through blood filter (prevents RBC debris, clots)

Transfusion Endpoints:

RBC transfusion: Stop at target Hgb (typically 7-9 g/dL in stable patients; 9-10 in CAD/sepsis; higher in hemorrhagic shock until source control)
Overload risk: Limit to 2 units q6h in CHF/renal disease; diuretics if volume overload
Time limit: Complete infusion within 4 hours per unit (bacterial growth if longer)

Monitoring for Transfusion Reaction:

Vital sign changes: Fever, hypotension, tachycardia → STOP immediately
Hemoglobinuria: Dark urine = hemolysis (acute immune reaction or hemoglobin S disease if sickle trait)
Allergic symptoms: Urticaria, angioedema → continue slowly with diphenhydramine; stop if anaphylaxis (airway edema, hypotension)
Pulmonary signs: Hypoxemia, dyspnea, pulmonary edema → stop, assess for TRALI

Post-Transfusion Orders:

Recheck Hgb after 2-4 units (assess response)
Void urine (check for hemoglobinuria)
Document: Units transfused, patient response, vital signs

Transfusion Reaction Recognition & Management (See Transfusion Reactions section above)

Emergency Transfusion

“Type O Negative” (uncrossmatched):

Used when crossmatch/typing unavailable & massive hemorrhage
<5 minutes to availability (already blood-warmed, checked for leaks)
Switch to type-specific once available (even if O neg already given)
Risks: Alloimmunization, minor incompatibilities

Massive Transfusion Triggers:

4 units PRBC in 1 hour
10 units in 24 hours
Anticipated need (>2 PRBC estimated)
Activate MTP (massive transfusion protocol) → 1:1:1 RBC:FFP:platelets on auto-delivery

Walking Blood Bank (Family Donor Program)

Indications: Small clinic/rural setting with limited blood bank access; anticipated massive hemorrhage (obstetric, trauma)

Pre-Planning:

Recruit family members as donors (usually O+ or type-matched)
Screen: ABO/Rh typing + basic serology (RPR, anti-HIV, anti-HCV, anti-HTLV, HBsAg) at least once
Brief health history (no travel to malaria areas, recent tattoos, drug use)
Document consent

Emergency Use:

At time of need: Blood type donor (rapid), cross-match (limited time)
Direct transfusion: Vein-to-vein connection (uncommon now, risk of air embolism)
Bag collection: Standard collection into CPD preservative (blood bank setup); use within 48 hours
Volume: 450 mL per collection (RBCs ~200 mL; plasma ~250 mL)

Limitations:

Limited donors (may not have compatible blood)
Variable blood quality (dependent on donor health)
Risks: Infection transmission (screening interval dependent), donor fatigue/anemia
Best for: Obstetric hemorrhage (lower infection transmission risk than massive trauma transfusion from multiple donors)

Massive Transfusion Protocol (MTP)

Ratios: 1:1:1 RBC:FFP:platelets (1 unit PRBC : 1 unit FFP : 6 units platelets) or 2:1:1 (modified based on lab results, facility guidelines)

Typical Case:

Patient: 70 kg with massive hemorrhage
Initial package: 6 units PRBC, 6 units FFP, 1 six-pack platelets (40 units)
Repeat CBC/INR/fibrinogen every 4-6 units; adjust ratios (if fibrinogen low → cryo; if INR elevated → more FFP; if platelet count low → more platelets)

Complications & Mitigation:

Dilutional coagulopathy: Frequent monitoring, transfusion of FFP/cryo/platelets before labs back (empiric)
Hypothermia: Warm IV fluids (fluid warmer, rapid infusion device), avoid room-temperature blood
Hyperkalemia (RBC lysis from cold storage): EKG monitoring, calcium gluconate, insulin + dextrose if peaked T-waves
Hypocalcemia (citrate toxicity from FFP/platelets): Monitor ionized Ca (especially if infusion >1 unit/min); calcium gluconate 10% IV slow if prolonged coagulopathy
Acidosis: Occurs from shock (lactate); improves with hemorrhage control (not treated with alkali acutely)
Rhabdomyolysis (crush injury): Risk of hyperkalemia/AKI; aggressive hydration, monitor renal function

Damage Control Resuscitation:

Permissive hypotension (SBP 80-90 mmHg) until hemorrhage controlled (minimize bleeding while maintaining vital perfusion)
Early transfusion of O neg/type-matched
Early surgical control (operating room, not ICU resuscitation alone)
After control: Warm, restore normal BP, complete resuscitation