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Thermoregulatory response to intraoperative head-down tilt
Yasufumi Nakajima1, Toshiki Mizobe, Takashi Matsukawa
1Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto, Japan.
Anesthesia and Analgesia
|January 5, 2002
Summary
Leg-up positions worsen intraoperative hypothermia by lowering the vasoconstriction threshold. Head-down tilt (Trendelenburg position) does not affect this threshold or worsen hypothermia, negating the need for special thermal management.
Area of Science:
- Anesthesiology
- Physiology
- Surgical Patient Care
Background:
- Thermoregulation and cardiovascular regulation are interconnected within the central nervous system.
- Understanding these interactions is crucial for optimizing intraoperative patient management.
Purpose of the Study:
- To evaluate the impact of head-down tilt on intraoperative thermal and cardiovascular regulation.
- To compare these effects with supine, leg-up, and combined positions.
Main Methods:
- Thirty-two patients undergoing lower-abdominal surgery were randomized into four positional groups.
- Core temperature, skin-temperature gradients, cardiac output, and pressures were monitored.
- Measurements were taken for 3 hours post-anesthesia induction.
Main Results:
- Leg-up positions significantly increased right atrial transmural pressure and cardiac index.
- The vasoconstriction threshold was reduced in leg-up positions, leading to aggravated hypothermia.
- Head-down tilt alone did not significantly alter right atrial pressure or the vasoconstriction threshold.
Conclusions:
- Intraoperative hypothermia is exacerbated by the leg-up position due to a reduced vasoconstriction threshold.
- Head-down tilt (Trendelenburg) does not worsen hypothermia or reduce the vasoconstriction threshold.
- Special thermal management for head-down tilt is unnecessary unless combined with the leg-up position.