Skip to main content
placeholder image

A vascular mechanism to explain thermally mediated variations in deep-body cooling rates during immersion treatment of profoundly hyperthermic individuals

Journal Article


Abstract


  • Physiologically trivial time differences for cooling the intrathoracic viscera of hyperthermicindividuals have been reported between cold- and temperate-water immersion treatments. Oneexplanation for that observation is reduced convective heat delivery to the skin during coldimmersion, and this study was designed to test both the validity of that observation, and its under-lying hypothesis. Eight healthy men participated in four head-out water immersions: two whennormothermic, and two after exercise-induced, moderate-to-profound hyperthermia. Two watertemperatures were used within each thermal state: temperate (26◦C) and cold (14◦C). Tissuetemperatures were measured at three deep-body sites (oesophagus, auditory canal and rectum)and eight skin surfaces, with cutaneous vascular responses simultaneously evaluated from bothforearms (laser-Doppler flowmetry and venous-occlusion plethysmography). During the coldimmersion of normothermic individuals, oesophageal temperature decreased relative to baseline(−0.31◦C over 20 min; P < 0.05), whilst rectal temperature increased (0.20◦C; P < 0.05). Whenrendered hyperthermic, oesophageal (−0.75◦C) and rectal temperatures decreased (−0.05◦C)during the transition period (<8.5 min, mostly in air at 22◦C), with the former dropping to37.5◦C only 54 s faster when immersed in cold rather than in temperate water (P < 0.05).Minimal cutaneous vasoconstriction occurred during either normothermic immersion, whereaspronounced constriction was evident during both immersions when subjects were hyperthermic,with the colder water eliciting a greater vascular response (P < 0.05). It was concluded that therapid intrathoracic cooling of asymptomatic, hyperthermic individuals in temperate water wasa reproducible phenomenon, with slower than expected cooling in cold water brought about bystronger cutaneous vasoconstriction that reduced convective heat delivery to the periphery

UOW Authors


  •   Caldwell, Joanne N. (external author)
  •   van den Heuvel, Anne (external author)
  •   Kerry, Pete (external author)
  •   Clark, Mitchell (external author)
  •   Peoples, Gregory
  •   Taylor, Nigel A.S.. (external author)

Publication Date


  • 2018

Citation


  • Caldwell, J. N., van den Heuvel, A. M. J., Kerry, P., Clark, M. J., Peoples, G. E. & Taylor, N. A.S.. (2018). A vascular mechanism to explain thermally mediated variations in deep-body cooling rates during immersion treatment of profoundly hyperthermic individuals. Experimental Physiology, 103 (4), 512-522.

Scopus Eid


  • 2-s2.0-85042561782

Number Of Pages


  • 10

Start Page


  • 512

End Page


  • 522

Volume


  • 103

Issue


  • 4

Place Of Publication


  • United Kingdom

Abstract


  • Physiologically trivial time differences for cooling the intrathoracic viscera of hyperthermicindividuals have been reported between cold- and temperate-water immersion treatments. Oneexplanation for that observation is reduced convective heat delivery to the skin during coldimmersion, and this study was designed to test both the validity of that observation, and its under-lying hypothesis. Eight healthy men participated in four head-out water immersions: two whennormothermic, and two after exercise-induced, moderate-to-profound hyperthermia. Two watertemperatures were used within each thermal state: temperate (26◦C) and cold (14◦C). Tissuetemperatures were measured at three deep-body sites (oesophagus, auditory canal and rectum)and eight skin surfaces, with cutaneous vascular responses simultaneously evaluated from bothforearms (laser-Doppler flowmetry and venous-occlusion plethysmography). During the coldimmersion of normothermic individuals, oesophageal temperature decreased relative to baseline(−0.31◦C over 20 min; P < 0.05), whilst rectal temperature increased (0.20◦C; P < 0.05). Whenrendered hyperthermic, oesophageal (−0.75◦C) and rectal temperatures decreased (−0.05◦C)during the transition period (<8.5 min, mostly in air at 22◦C), with the former dropping to37.5◦C only 54 s faster when immersed in cold rather than in temperate water (P < 0.05).Minimal cutaneous vasoconstriction occurred during either normothermic immersion, whereaspronounced constriction was evident during both immersions when subjects were hyperthermic,with the colder water eliciting a greater vascular response (P < 0.05). It was concluded that therapid intrathoracic cooling of asymptomatic, hyperthermic individuals in temperate water wasa reproducible phenomenon, with slower than expected cooling in cold water brought about bystronger cutaneous vasoconstriction that reduced convective heat delivery to the periphery

UOW Authors


  •   Caldwell, Joanne N. (external author)
  •   van den Heuvel, Anne (external author)
  •   Kerry, Pete (external author)
  •   Clark, Mitchell (external author)
  •   Peoples, Gregory
  •   Taylor, Nigel A.S.. (external author)

Publication Date


  • 2018

Citation


  • Caldwell, J. N., van den Heuvel, A. M. J., Kerry, P., Clark, M. J., Peoples, G. E. & Taylor, N. A.S.. (2018). A vascular mechanism to explain thermally mediated variations in deep-body cooling rates during immersion treatment of profoundly hyperthermic individuals. Experimental Physiology, 103 (4), 512-522.

Scopus Eid


  • 2-s2.0-85042561782

Number Of Pages


  • 10

Start Page


  • 512

End Page


  • 522

Volume


  • 103

Issue


  • 4

Place Of Publication


  • United Kingdom