Peripheral blood flow during rewarming from mild hypothermia in humans

Abstract

During the initial stages of rewarming from hypothermia, there is a continued cooling of the core, or after-drop in temperature, that has been attributed to the return of cold blood due to peripheral vasodilatation, thus causing a further decrease of deep body temperature. To examine this possibility more carefully, subjects were immersed in cold water (17 degrees C), and then rewarmed from a mildly hypothermic state in a warm bath (40 degrees C). Measurements of hand blood flow were made by calorimetry and of forearm, calf, and foot blood flows by straingauge venous occlusion plethysmography at rest (Ta = 22 degrees C) and during rewarming. There was a small increase in skin blood flow during the falling phase of core temperature upon rewarming in the warm bath, but none in foot blood flow upon rewarming at room air, suggesting that skin blood flow seems to contribute to the after-drop, but only minimally. Limb blood flow changes during this phase suggest that a small muscle blood flow could also have contributed to the after-drop. It was concluded that the after-drop of core temperature during rewarming from mild hypothermia does not result from a large vasodilatation in the superficial parts of the periphery, as postulated. The possible contribution of mechanisms of heat conduction, heat convection, and cessation of shivering thermogenesis were discussed.

Considerations for the measurement of core, skin and mean body temperatures

“…Beyond point B, rectal temperature fell below oesophageal temperature, and remained so thereafter, as eventually did gastrointestinal (point C) and auditory-canal temperatures (point D). This cross-over phenomenon is also widely reported (Eichna, 1949;Bligh, 1957a;Cooper and Kenyon, 1957;Severinghaus, 1959;Benzinger and Taylor, 1963;Minard and Copman, 1963;Piironen, 1970;Keatinge and Sloan, 1975;Gibson et al, 1981;Golden and Hervey, 1981;Hayward et al, 1984;Savard et al, 1985;Webb, 1986;Ash et al, 1992;Teunissen et al, 2012). Indeed, the current authors were unable to find exceptions, yet its implications have rarely been discussed.…”

“…This phase delay of the rectal temperature response is frequently observed, varying between 6-60 min (Burton and Bazett, 1936;Bazett et al, 1948;Eichna, 1949;Cooper and Kenyon, 1957;Gollan, 1959;Äikäs et al, 1962;Benzinger and Taylor, 1963;Guidry and McDowell, 1966;Piironen, 1970;Saltin et al, 1970;Molnar and Read, 1974;Edwards et al, 1978;Hayward et al, 1984;Savard et al, 1985;Vallerand et al, 1992b;Lee et al, 2000;Lee et al, 2010;Nagano et al, 2010;Teunissen et al, 2012). One consequence is that the offset between rectal and oesophageal temperatures can change from o0.5°C to 4 10°C during extreme states (Gollan, 1959), another is that thermoeffector activation may precede rectal temperature changes (Benzinger and Taylor, 1963;Snellen, 1969;Todd et al, 2014), and a third is that steady-state rectal temperatures during exercise may take 50 min to be obtained (Greenleaf and Castle, 1972), depending upon the compensability of the conditions.…”

Postexertional airway rewarming and thermally induced asthma. New insights into pathophysiology and possible pathogenesis.

“…It is not yet known ifthe airway smooth muscle in humans responds in a similar fashion, but obviously ifit did, such effects could be quite important in the pathogenesis of EIA. Alternatively, if the combination of the cooling of hyperpnea and the abrupt rewarming that occurs with its cessation were to affect the smooth muscle of the bronchial vessels as it does that in the vessels of the skin (28,29), a reactive hyperemia could develop. This in turn could result in luminal narrowing from vascular engorgement and edema in the mucosa and submucosa.…”

Brief Rewarming Blunts Hypothermia-Induced Alterations in Sensation, Motor Drive and Cognition

“…Most research has used prolonged passive external rewarming lasting from 30 min to several hours using a water bath, air inhalation, or forced air. These studies have focused on the direct effects of rewarming from hypothermia on the kinetics of physiological responses including body temperature (Hoskin et al, 1986; Kumar et al, 2015), cardiovascular parameters (Hayward et al, 1984; Savard et al, 1985), subjective sensation (Kumar et al, 2015), metabolic heat production (MHP), and heat gain (Goheen et al, 1997). The functional consequences of applying brief (5-min) whole-body rewarming on cognitive and neurophysiological functions in mildly hypothermic subjects have not been investigated.…”