title: Recovery from mild hypothermia can be accelerated by mechanically distending blood vessels in the hand.
abstract: Peripheral vasoconstriction decreases thermal conductance of hypothermic individuals, making it difficult to transfer externally applied heat to the body core. We hypothesized that increasing blood flow to the skin of a hypothermic individual would enhance the transfer of exogenous heat to the body core, thereby increasing the rate of rewarming. External auditory meatus temperature (TEAM) was monitored in hypothermic subjects during recovery from general anesthesia. In 10 subjects, heat (45-46 degreesC, water-perfused blanket) was applied to a single forearm and hand that had been placed in a subatmospheric pressure environment (-30 to -40 mmHg) to distend the blood vessels. Heat alone was applied to control subjects (n = 6). The application of subatmospheric pressure resulted in a 10-fold increase in rewarming rates as determined by changes in TEAM [13.6 +/- 2.1 (SE) degreesC/h in the experimental group vs. 1.4 +/- 0.1 degreesC/h in the control group; P < 0.001]. In the experimental subjects, the rate of change of TEAM decreased sharply as TEAM neared the normothermic range.
authors.affiliation: Department of Biological Sciences, School of Medicine, Stanford University, Stanford, California 94305, USA. dagrahn@leland.stanford.edu
authors.forename: D
authors.initials: D
authors.lastname: Grahn
authors.forename: J G
authors.initials: JG
authors.lastname: Brock-Utne
authors.forename: D E
authors.initials: DE
authors.lastname: Watenpaugh
authors.forename: H C
authors.initials: HC
authors.lastname: Heller
mesh_terms: D000328:Adult; D000368:Aged; D000399:Air Pressure; D001810:Blood Volume / Q000502:physiology; D001831:Body Temperature / Q000502:physiology; D005260:Female; D006225:Hand / Q000098:blood supply*; D006358:Hot Temperature; D006801:Humans; D007035:Hypothermia / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010812:Physical Stimulation; D012039:Regional Blood Flow / Q000502:physiology; D017694:Rewarming; D012881:Skin Temperature / Q000502:physiology; D013997:Time Factors