Difference between revisions of "Keeler"
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'''<span style="font-size:12.0pt"><span style="line-height:107%">Citation:</span></span>'''<span style="font-size:12.0pt"><span style="line-height:107%">Keeler JM, Greenshields JT, Goss CS, Baker TB, Chapman RF, Johnson BD, Schlader ZJ. Modification of thermoregulation during cold-water immersion by normobaric hypoxia. Undersea and Hyperbaric Medical Society. 2021, 4(3):344-345.</span></span> | '''<span style="font-size:12.0pt"><span style="line-height:107%">Citation:</span></span>'''<span style="font-size:12.0pt"><span style="line-height:107%">Keeler JM, Greenshields JT, Goss CS, Baker TB, Chapman RF, Johnson BD, Schlader ZJ. Modification of thermoregulation during cold-water immersion by normobaric hypoxia. Undersea and Hyperbaric Medical Society. 2021, 4(3):344-345.</span></span> | ||
| − | '''<span style="font-size:12.0pt"><span style="line-height:107%">Lead author’s name and email:</span></span>'''<span style="font-size:12.0pt"><span style="line-height:107%">J. M. Keeler : jmkeeler@iu.edu</span></span> | + | '''<span style="font-size:12.0pt"><span style="line-height:107%">Lead author’s name and email:</span></span>'''<span style="font-size:12.0pt"><span style="line-height:107%">J. M. Keeler : jmkeeler@iu.edu</span></span> |
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'''<span style="font-size:12.0pt"><span style="line-height:107%">Kill or update by</span></span>'''<span style="font-size:12.0pt"><span style="line-height:107%">: January 2024</span></span> | '''<span style="font-size:12.0pt"><span style="line-height:107%">Kill or update by</span></span>'''<span style="font-size:12.0pt"><span style="line-height:107%">: January 2024</span></span> | ||
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Latest revision as of 01:37, 31 January 2022
Possible reduction in core temperature but not of energy expenditure when breathing FiO2 0.13 compared to FiO2 0.21 during head-out cold-water immersion.
Clinical bottom line:
- No difference in energy expenditure in normobaric cold-water immersion between breathing a hypoxic mixture (FiO2 0.13) compared to air.
- Possible small reduction in rectal temperature after the hypoxic exposure (see comments).
Citation:Keeler JM, Greenshields JT, Goss CS, Baker TB, Chapman RF, Johnson BD, Schlader ZJ. Modification of thermoregulation during cold-water immersion by normobaric hypoxia. Undersea and Hyperbaric Medical Society. 2021, 4(3):344-345.
Lead author’s name and email:J. M. Keeler : jmkeeler@iu.edu
Three-part clinical question:For head-out cold-water (22°C) immersion in normobaric conditions, does a period breathing FiO2 0.13 compared to breathing FiO2 0.21 (air), result in decreased energy expenditure and core temperature?
Search terms:Thermoregulation, normobaric hypoxia, cold-water immersion
The study:Non-blinded randomised crossover trial with intention to treat.
The study patients:Nine healthy adult volunteers at 27±4 years.
Control group:(N = 9; 9 analysed): Head-out cold-water (22°C) immersion in normobaric conditions for up to an hour breathing a normoxic mixture (FiO2 = 0.21).
Experimental group:(N = 9; 9 analysed): As above, but instead breathing a hypoxic mixture (FiO2 = 0.13).
The Evidence:
Measure |
Air exp. |
Hypoxia exp |
Difference |
95% CI | ||
Mean |
SD |
Mean |
SD | |||
|
Rectal temperature (oC) at end of exposure |
36.7 |
0.5 |
36.4 |
0.5 |
0.3 |
0.05 to 0.55 |
|
Energy expenditure (kilojoules) (unit time not given) |
11.8 |
2.8 |
13.1 |
4.2 |
1.3 |
-11.4 to 14.0 |
Comments
- Abstract in conference proceedings only so many details missing. Waiting for the authors’ full account. Exposures were ‘up to 1 hour’ – the authors have not reported actual durations of exposure.
- Small sample size of 9 individuals, no power calculation available.
- Using the published figures, we conclude the difference in rectal temperatures was statistically significantly lower in hypoxia exposure but this may be a misinterpretation (figures may be within group).
- Between group differences in trapezius and supraclavicular sites were not statistically different.
- The average arterial oxygen saturation in the hypoxic group was 90% versus 99% with normoxia.
Appraised by: Bosco Tran bosco.tran@student.unsw.edu.au
Kill or update by: January 2024
