CHAPTER 31 Temperature Disturbances
3 Does hypothermia have an impact on patient outcome?
Mild hypothermia (1° to 3° C) has the following effects:
Increases incidence of surgical site infections (SSIs). Although this is a multifactorial problem, it has been noted that vasoconstriction secondary to hypothermia decreases blood flow to the wound and bacterial killing by neutrophils.
TABLE 31-1 The Effects of Hypothermia on Organ Systems
| System | Effects |
|---|---|
| Vascular | Increases systemic vascular resistance and peripheral hypoperfusion; plasma volume decreases because of cold diuresis |
| Cardiac | Decreases heart rate, contractility, and cardiac output and produces arrhythmias |
| Pulmonary | Increases pulmonary vascular resistance; decreases hypoxic pulmonary vasoconstriction; increases ventilation-perfusion mismatching; depresses ventilatory drive; decreases bronchial muscle tone increasing anatomic dead space; oxyhemoglobin dissociation curve shifts to the left |
| Renal | Decreases renal blood flow and glomerular filtration rate; impaired sodium resorption and diuresis leading to hypovolemia |
| Hepatic | Decreases hepatic blood flow, metabolic and excretory functions |
| Central nervous system | Decreases cerebral blood flow; increases cerebral vascular resistance; oxygen consumption decreases by 7%/°C; evoked potential latencies are increased; MAC is decreased |
| Hematologic | Decreased platelet aggregation and clotting factor activity; increased blood viscosity, impaired immune response |
| Metabolic | Basal metabolic rate decreases; hyperglycemia and insulinopenia; decreased oxygen consumption and CO2 production |
| Healing | Increased wound infections |
MAC, Minimum alveolar concentration.
4 Characterize the different stages of hypothermia
Mild hypothermia (32° to 35° C, 90° to 95° F) is associated with mild central nervous system depression (dysarthria, amnesia, ataxia, and apathy), decreased basal metabolic rate, tachycardia, peripheral vasoconstriction, and shivering.
