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The attenuating effect of heat and hypovolemia on the human diving response.
Alaska Med. 1993 Jul-Sep; 35(3):199-203.AM

Abstract

Seven healthy adult volunteers underwent 30-second facial immersions in ice water before and during 36 minutes exposure to intense ambient heat (68 degrees C) on separate, non-consecutive days: one normovolemic and the second with thiazide-induced, 10% hypovolemia. The normovolemic, preheat immersion induced a heart rate (H.R.) decrease from 74 +/- 6 to 48 +/- 5 bpm (-35%) and a forearm blood flow (F.B.F.) decrease from 3.5 +/- 1.6 to 0.8 +/- 0.3 ml/(100 ml min) (-77%). Pre-heat changes were similar for hypovolemic subjects. After 36 minutes of heat exposure there was a 07 degrees C increase in esophageal temperature and a four-fold increase in F.B.F. for normovolemic and a two-fold increase in F.B.F. for hypovolemic subjects. Heating reduced diving bradycardia more than did superimposed hypovolemia. Four subjects had diving tachycardia after hypovolemic heating. We concluded that the bradycardia response to facial immersion can be overridden by reducing the central circulating blood volume by heat and that this effect is enhanced by hypovolemia.

Authors+Show Affiliations

Ophthalmic Associates, Anchorage, Alaska 99501.No affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

8109690

Citation

Arnold, R W., and E R. Nadel. "The Attenuating Effect of Heat and Hypovolemia On the Human Diving Response." Alaska Medicine, vol. 35, no. 3, 1993, pp. 199-203.
Arnold RW, Nadel ER. The attenuating effect of heat and hypovolemia on the human diving response. Alaska Med. 1993;35(3):199-203.
Arnold, R. W., & Nadel, E. R. (1993). The attenuating effect of heat and hypovolemia on the human diving response. Alaska Medicine, 35(3), 199-203.
Arnold RW, Nadel ER. The Attenuating Effect of Heat and Hypovolemia On the Human Diving Response. Alaska Med. 1993;35(3):199-203. PubMed PMID: 8109690.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The attenuating effect of heat and hypovolemia on the human diving response. AU - Arnold,R W, AU - Nadel,E R, PY - 1993/7/1/pubmed PY - 1993/7/1/medline PY - 1993/7/1/entrez SP - 199 EP - 203 JF - Alaska medicine JO - Alaska Med VL - 35 IS - 3 N2 - Seven healthy adult volunteers underwent 30-second facial immersions in ice water before and during 36 minutes exposure to intense ambient heat (68 degrees C) on separate, non-consecutive days: one normovolemic and the second with thiazide-induced, 10% hypovolemia. The normovolemic, preheat immersion induced a heart rate (H.R.) decrease from 74 +/- 6 to 48 +/- 5 bpm (-35%) and a forearm blood flow (F.B.F.) decrease from 3.5 +/- 1.6 to 0.8 +/- 0.3 ml/(100 ml min) (-77%). Pre-heat changes were similar for hypovolemic subjects. After 36 minutes of heat exposure there was a 07 degrees C increase in esophageal temperature and a four-fold increase in F.B.F. for normovolemic and a two-fold increase in F.B.F. for hypovolemic subjects. Heating reduced diving bradycardia more than did superimposed hypovolemia. Four subjects had diving tachycardia after hypovolemic heating. We concluded that the bradycardia response to facial immersion can be overridden by reducing the central circulating blood volume by heat and that this effect is enhanced by hypovolemia. SN - 0002-4538 UR - https://www.unboundmedicine.com/medline/citation/8109690/The_attenuating_effect_of_heat_and_hypovolemia_on_the_human_diving_response_ DB - PRIME DP - Unbound Medicine ER -