Comparison of Heat Donation Through the Head or Torso on Mild Hypothermia Rewarming

Sran, Bhupinder Jit K.; McDonald, Gerren K.; Steinman, Alan M.; Gardiner, Phillip F.; Giesbrecht, Gordon G.

doi:10.1016/j.wem.2013.10.005

Cited by 6 publications

(11 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While dehydration may contribute to AMS, it could also decrease a climber’s chances of reaching the summit by contributing to a sense of exhaustion [26], with subsequent slower ascent rate that could increase a climber's exposure to weather and treacherous alpine conditions. Of note, overhydration is not recommended to prevent AMS [27], and could potentially lead to fatal dilutional hyponatremia.…”

Section: Discussionmentioning

confidence: 99%

Hydration Status as a Predictor of High-altitude Mountaineering Performance

Ladd

Shea

Bagley

et al. 2016

Cureus

View full text Add to dashboard Cite

Background: Hydration status is a controversial determinant of athletic performance. This relationship has not been examined with mountaineering performance.Methods: This was a prospective observational study of mountaineers who attempted to climb Denali in Alaska. Participants’ urine specific gravity (SG), and ultrasound measurements of the inferior vena cava size and collapsibility index (IVC-CI) were measured at rest prior to ascent. Upon descent, climbers reported maximum elevation gained for determination of summit success.Results: One hundred twenty-one participants enrolled in the study. Data were collected on 111 participants (92% response rate); of those, 105 (87%) had complete hydration data. Fifty-seven percent of study participants were found to be dehydrated by IVC-CI on ultrasound, and 55% by urine SG. No significant association was found with summit success and quantitative measurements of hydration: IVC-CI (50.4% +/- 15.6 vs. 52.9% +/- 15.4, p = 0.91), IVC size (0.96 cm +/- 0.3 vs. 0.99 cm +/- 0.3, p = 0.81), and average SG (1.02 +/- 0.008 vs. 1.02 +/- 0.008, p = 0.87). Categorical measurements of urine SG found 24% more successful summiters were hydrated at 14 Camp, but this was not found to be statistically significant (p = 0.56). Summit success was associated with greater water-carrying capacity on univariate analysis only: 2.3 L, 95% confidence interval (2.1 – 2.5) vs. 2.1 L, 95% confidence interval (2 – 2.2); p < 0.01.Conclusions: Intravascular dehydration was found in approximately half of technical high-altitude mountaineers. Hydration status was not significantly associated with summit success, but increased water-carrying capacity may be an easy and inexpensive educational intervention to improve performance.

show abstract

Section: Discussionmentioning

confidence: 99%

Hydration Status as a Predictor of High-altitude Mountaineering Performance

Ladd

Shea

Bagley

et al. 2016

Cureus

View full text Add to dashboard Cite

show abstract

“…During the last 30 min of rewarming, there was a tendency for higher T es with active heating, although this was only statistically significant for the TW condition. The positive aspect of these results is that the head provides a viable alternative for heat donation when TW is contraindicated, not only when shivering is intact 6 but also when shivering is absent.…”

Section: Discussionmentioning

confidence: 98%

Efficacy of Head and Torso Rewarming Using a Human Model for Severe Hypothermia

Kulkarni

Hildahl

Dutta

et al. 2019

Wilderness & Environmental Medicine

Self Cite

View full text Add to dashboard Cite

Introduction-To evaluate the rewarming effectiveness of a similar amount of heat (from a charcoal heater) applied to either the head or torso in a human model for severe hypothermia in which shivering is pharmacologically inhibited in mildly hypothermic subjects. Methods-Six male subjects were cooled on 3 different occasions, each in 8˚C water for 60 min, or to a lowest core temperature of 35˚C. Shivering was inhibited by intravenous meperidine (1.5 mg¢kg ¡1), administered during the last 10 min of the cold-water immersion. Subjects then exited from the cold water, were dried, and were placed in a 3-season sleeping bag for 120 min in one of the following conditions: spontaneous rewarming only, charcoal heater on the head, or charcoal heater on the torso. Supplemental meperidine (to a maximum cumulative dose of 3.3 mg¢kg ¡1) was administered as required during rewarming to suppress shivering. Results-No significant differences were found in the postcooling afterdrop amount or core rewarming rates among the 3 conditions (0.8˚C¢h ¡1). During the last 30 min of rewarming the net heat gain was significantly higher in the head (85.8 §25.3 W) and torso (81.5 §6.3 W) conditions compared with the spontaneous condition (56.9 §12 W) (P<0.05). Conclusions-In our study, head and torso warming had the same core rewarming rates when shivering was pharmacologically inhibited in mildly hypothermic subjects. Therefore, in nonshivering cold subjects, head warming is a viable alternative if torso warming is contraindicated (eg, when performing cardiopulmonary resuscitation or working on open chest wounds).

show abstract

“…Meperidine was administered in some of these subjects in order to attenuate shivering, allowing one to calculate the mean value of M (W/m 2 ) for shivering and non-shivering subjects separately. We calculated an M value for a shivering victim (M shiv ) from 11 studies with a total of 77 participants (Giesbrecht et al 1994 ; Hultzer et al 2005 ; Grissom et al 2008 ; Pretorius et al 2008 ; Lundgren et al 2009 ; Thomassen et al 2011 ; Sran et al 2014 ; Kumar et al 2015 ; Henriksson et al 2015 ; Kulkarni et al 2019 ; Hurrie et al 2020 ). An M value for a non-shivering patient (M non-shiv ) (e.g., a patient treated with opioids) was calculated from six studies with a total of 37 subjects (Giesbrecht et al 2005 ; Hultzer et al 2005 ; Pretorius et al 2006 ; Lundgren et al 2009 ; Kulkarni et al 2019 ; Hurrie et al 2020 )—see Supplementary file .…”

Section: Methodsmentioning

confidence: 99%

Efficacy of warming systems in mountain rescue: an experimental manikin study

et al. 2020

View full text Add to dashboard Cite

Mountain accident casualties are often exposed to cold and windy weather. This may induce post-traumatic hypothermia which increases mortality. The aim of this study was to assess the ability of warming systems to compensate for the victim's estimated heat loss in a simulated mountain rescue operation. We used thermal manikins and developed a thermodynamic model of a virtual patient. Manikins were placed on a mountain rescue stretcher and exposed to wind chill indices of 0°C and − 20°C in a climatic chamber. We calculated the heat balance for two simulated clinical scenarios with both a shivering and non-shivering victim and measured the heat gain from gel, electrical, and chemical warming systems for 3.5 h. The heat balance in the simulated shivering patient was positive. In the non-shivering patient, we found a negative heat balance for both simulated weather conditions (− 429.53 kJ at 0°C and − 1469.78 kJ at − 20°C). Each warming system delivered about 300 kJ. The efficacy of the gel and electrical systems was higher within the first hour than later (p < 0.001). We conclude that none of the tested warming systems is able to compensate for heat loss in a simulated model of a non-shivering patient whose physiological heat production is impaired during a prolonged mountain evacuation. Additional thermal insulation seems to be required in these settings.

show abstract

Comparison of Heat Donation Through the Head or Torso on Mild Hypothermia Rewarming

Cited by 6 publications

References 46 publications

Hydration Status as a Predictor of High-altitude Mountaineering Performance

Hydration Status as a Predictor of High-altitude Mountaineering Performance

Efficacy of Head and Torso Rewarming Using a Human Model for Severe Hypothermia

Efficacy of warming systems in mountain rescue: an experimental manikin study

Contact Info

Product

Resources

About