Table 1 Comparison of physiologic and metabolic changes associated with hemorrhagic shock with those changes specific to hemorrhagic shock combined spontaneous hypothermia or induced therapeutic hypothermia.

Cardiac

Hypotension, tachycardia

Hypovolemic shock

Cardiac depression

Bradycardia

Arrhythmias with worsening hypothermia - J waves

Bradycardia

Decreased risk of cardiac arrest

Induced cardiac arrest on CPB with low flow state

Respiratory

Variable

Central respiratory depression

Variable

Carefully monitored

Patient intubated and monitored on ventilator

Metabolic

Increase oxygen requirements Switch from aerobic to anaerobic metabolism

Energy (ATP) depletion

Supply/demand mismatch

Reduced metabolic requirements

allowing supply to meet demand

ATP reserved with reduced metabolism.

No oxygen or substrates requirements

Coagulopathy

Trauma-induced consumptive coagulopathy

Reperfusion dilutional coagulopathy

Decrease platelets and coagulation factors activity

Continuous monitoring of PT and PTT

Irrelevant

Mental Status

Variable

Progressive depression in mental status and eventually coma with flat EEG

Patient deliberately sedated and paralyzed

Patient deliberately sedated and paralyzed

Immune system

Initiation of inflammatory response with multiple organ damage

Blunted cytokine production and neutrophil migration with increased risk of infections

Decreased immune and inflammatory response

Antibiotic prophylaxis

Antibiotics coverage and sepsis precaution during hypothermia induction

Shivering

Not observed early in hemorrhage

Increased attempt to produce heat increases energy demand and over-utilizes ATP

Muscular blockade to control shivering.

Muscular blockade to control shivering

Hyperglycemia

Irrelevant

Decreased insulin production and resistance leads to hyperglycemia

Controlled and reversible

Controlled and reversible