低体温 精品课件

reduced hepatic blood flow
Muscle relaxants
● Evaporation via skin and mucosa, accounting for5% to 20%
● Conduction (heat loss by direct contact between surfaces), accounting for about 3% to 5%.
➢ Perioperative hypothermia is common, with an incidence ranging between 20 and 70%
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• THERMAL DISCOMFORT AND ANXIETY • CARDIAC COMPLICATIONS • DELAYED DISCHARGE FROM THE PACU • PROLONGED HOSPITALIZATION • TRANSFUSION REQUIREMENT
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IMPAIRED PHARMACODYNAMICS
Consequences of perioperative hypothermia

• IMPAIRED PHARMACODYNAMICS • SURGICAL SITE INFECTIONS AND
COMPLICATIONS • BLOOD LOSS AND COAGULOPATHY • SHIVERING
PERIOPERATIVE HYPOTHERMIA IS COMMON AFTER INDUCTION OF ANESTHESIA, BUT NOT AT THE END OF SURGERY
the distribution of core temperature as a function of time after induction of anesthesia in a cohort of 58,814 patients having noncardiac surgery at the Cleveland Clinic
the incidence of hypothermia under various core temperature thresholds
• After 45 minutes of induction of general anesthesia, almost two-thirds of patients reached the hypothermia threshold of 36°C.
➢ Induction of anesthesia causes several physiologic changes. In particular, the so-called redistribution effect within 60–90 minutes of anesthesia causes a decrease in body core temperature.
Most cellular functions and enzyme activity are temperature-dependent. hypothermia prolongs the actions of various drugs
Propofol and fentanyl
A 3oC decrease in core temperature results in an approximately 28% increase in plasma propofol concentration, largely as a result of
The physical exchange of heat between the body and its environment occurs by means of four mechanisms:
● Radiation, accounting for about 50% to 70%
● Convection (heat loss via the ambient air stream), accounting for about 15% to 25%
The duration of perioperative hypothermia varies
Nearly half of all patients have core temperature < 36°C, and about 20 % of all patients have a core temperature < 35.5°C for more than 1 hour
• In addition, more than one-quarter reached the threshold of 35.5°C within 51 minutes of induction.
• After 71 minutes, 7% of all patients even reached 35°C. • Although perioperative hypothermia is most common in the first hour
➢ Perioperative warming was rare during the previous century, but was subsequently identified as a significant contributor to perioperative morbidity and mortality.
after induction of anesthesia, it nevertheless remains common in about 20% of all patients, even after 6 hours of surgery.
Phases of hypothermia under general anesthesia