II. Physiology
-
Blood Volume
- Adult: 7% or 70 ml/kg (~5 Liter Blood Volume for a 70 kg man)
- Child: 8-9% (80-90 ml/kg for a child)
- Blood Loss
- Each 10% drop in Blood Volume represents ~500 ml blood loss in average adult male (70 kg)
III. Findings: Class I Hemorrhage - Minimal Blood Loss
- Characteristics
- Blood Volume Loss <15%
- Adult blood loss <750 ml
- Cardiovascular
- Heart Rate normal or mild increase
- Pulses normal
- Blood Pressure normal
- pH normal
- Respiratory: Rate normal
- Neurologic
- Slightly anxious
- Glasgow Coma Score (GCS) baseline
- Skin
- Warm and pink
- Capillary Refill brisk (<2 seconds)
- Renal
- Base Deficit 0 to -2 mEq/L (normal)
- Normal Urine Output
- Adults: >0.5 ml/kg/hour (>30 cc/hour)
- Children: >1 ml/kg/hour
- Infants <1yo: >2 ml/kg/hour
- Reponse to Crystalloid Bolus (2000 ml in adults, 20 ml/kg in children)
- Rapid response with normalization of Vital Signs
IV. Findings: Class II Hemorrhage - Mild Blood Loss
- Characteristics
- Blood Volume Loss: 15-30%
- Adult: 750-1500 ml of blood loss
- Cardiovascular
- Tachycardia
- Diminished peripheral pulses
- Blood Pressure normal
- Normal pH
- Respiratory
- Mild Tachypnea
- Neurologic
- Irritable
- Glasgow Coma Score (GCS) baseline
- Skin
- Cool extremities
- Mottling
- Delayed Capillary Refill
- Renal
- Oliguria
- Increased specific gravity
- Base Deficit -2 to -6 mEq/L (Metabolic Acidosis)
- Response to Crystalloid Bolus (2000 ml in adults, 20 ml/kg in children)
- Moderate response, but Tachycardia may recurr
V. Findings: Class III Hemorrhage - Moderate Blood Loss
- Characteristics
- Blood Volume Loss: 30-40%
- Adults: 2000 ml blood loss
- Cardiovascular
- Significant Tachycardia
- Thready peripheral pulses
- Hypotension
- Metabolic Acidosis
- Respiratory: Moderate Tachypnea
- Neurologic
- Glasgow Coma Score (GCS) decreased
- Irritable or Combative
- Confused
- Lethargic
- Diminished pain response
- Skin
- Cool extremities, mottling or pallor
- Prolonged Capillary Refills
- Renal
- Oliguria
- Blood Urea Nitrogen (BUN) increased
- Base Deficit -6 to -10 mEq/L (Metabolic Acidosis)
- Reponse to Crystalloid Bolus (2000 ml in adults, 20 ml/kg in children)
- Transient response with recurrent Hypotension and Tachycardia
- Blood Transfusion needed (typically type specific blood)
- Surgical intervention is likely
VI. Findings: Class IV Hemorrhage - Severe Blood Loss
- Characteristics
- Blood Volume Loss: >40%
- Cardiovascular
- Severe Tachycardia
- Thready central pulses
- Significant Hypotension
- Significant acidosis
- Respiratory: Severe Tachypnea
- Neurologic
- Skin
- Cold extremities
- Pallor
- Cyanosis
- Renal
- Anuria
- Base Deficit <-10 mEq/L (severe Metabolic Acidosis)
- Reponse to Crystalloid Bolus (2000 ml in adults, 20 ml/kg in children)
- No significant response with recurrent Hypotension and Tachycardia
- Massive Blood Transfusion needed (starting with O negative blood)
- Emergent surgical intervention