CHAPTER 31 Temperature Disturbances
3 Does hypothermia have an impact on patient outcome?
Mild hypothermia (1° to 3° C) has the following effects:


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

6 Which physical processes contribute to a patient’s heat loss in the operating room?


8 Should all patients receive temperature monitoring within the operating room? What are acceptable sites for temperature monitoring?
10 Describe the electrocardiographic manifestations of hypothermia
KEY POINTS: Temperature Disturbances
1. Hypothermia is an extremely common event in the operating room because the environment and the effects of anesthetics increase heat loss. Anesthetics also decrease the ability to generate a response to hypothermia (shivering and vasoconstriction).
11 How does hypothermia affect the actions and metabolism of drugs used in the operative environment?
12 Discuss methods of rewarming


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2. Rajagopalan S., Mascha E., Na J., et al. The effects of mild perioperative hypothermia on blood loss and the transfusion requirement. Anesthesiology. 2008;108:71-77.
3. Sessler D.I. Temperature monitoring and perioperatiave thermoregulation. Anesthesiology. 2008;109:318-338.