Respiratory and other responses in subjects immersed in cold water

Key points Thermal and hypoxic stress commonly coexist in environmental, occupational and clinical settings, yet how the brain tolerates these multi‐stressor environments is unknown Core cooling by 1.0°C reduced cerebral blood flow (CBF) by 20–30% and cerebral oxygen delivery (CDO2) by 12–19% at sea level and high altitude, whereas core heating by 1.5°C did not reliably reduce CBF or CDO2 Oxygen content in arterial blood was fully restored with acclimatisation to 4330 m, but concurrent cold stress reduced CBF and CDO2 Gross indices of cognition were not impaired by any combination of thermal and hypoxic stress despite large reductions in CDO2 Chronic hypoxia renders the brain susceptible to large reductions in oxygen delivery with concurrent cold stress, which might make monitoring core temperature more important in this context Abstract Real‐world settings are composed of multiple environmental stressors, yet the majority of research in environmental physiology investigates these stressors in isolation. The brain is central in both behavioural and physiological responses to threatening stimuli and, given its tight metabolic and haemodynamic requirements, is particularly susceptible to environmental stress. We measured cerebral blood flow (CBF, duplex ultrasound), cerebral oxygen delivery (CDO2), oesophageal temperature, and arterial blood gases during exposure to three commonly experienced environmental stressors – heat, cold and hypoxia – in isolation, and in combination. Twelve healthy male subjects (27 ± 11 years) underwent core cooling by 1.0°C and core heating by 1.5°C in randomised order at sea level; acute hypoxia (PET,O2 = 50 mm Hg) was imposed at baseline and at each thermal extreme. Core cooling and heating protocols were repeated after 16 ± 4 days residing at 4330 m to investigate any interactions with high altitude acclimatisation. Cold stress decreased CBF by 20–30% and CDO2 by 12–19% (both P < 0.01) irrespective of altitude, whereas heating did not reliably change either CBF or CDO2 (both P > 0.08). The increases in CBF with acute hypoxia during thermal stress were appropriate to maintain CDO2 at normothermic, normoxic values. Reaction time was faster and slower by 6–9% with heating and cooling, respectively (both P < 0.01), but central (brain) processes were not impaired by any combination of environmental stressors. These findings highlight the powerful influence of core cooling in reducing CDO2. Despite these large reductions in CDO2 with cold stress, gross indices of cognition remained stable.

show abstract

“…the cold shock response, triggers hyperventilation and cerebral hypoperfusion when resting (Cooper et al . ; Mantoni et al . ).…”

Section: Discussionmentioning

confidence: 99%

Global REACH 2018: The influence of acute and chronic hypoxia on cerebral haemodynamics and related functional outcomes during cold and heat stress

Gibbons

Tymko

Thomas

et al. 2020

The Journal of Physiology

View full text Add to dashboard Cite

show abstract

“…In comparison with whole‐body, head‐out immersions, the magnitude of the stimulation of ventilation appears proportionally smaller. In 10°C water without apnoea, increases in ventilation from rest of 600% (Cooper et al 1976) and as high as 1000% (Tipton & Golden, 1987) were evident during the first minute of whole‐body, head‐out immersion. In the present study, non‐apnoeic face immersion gave a mean peak ventilation that was 97% greater than that at 33°C.…”

Section: Discussionmentioning

confidence: 99%

Human face‐only immersion in cold water reduces maximal apnoeic times and stimulates ventilation

Jay¹,

Christensen²,

White³

2007

Experimental Physiology

View full text Add to dashboard Cite

In two studies, the cold shock and diving responses were investigated after human face immersion without prior hyperventilation to explore the mechanism(s) accounting for reductions in maximal apnoeic times (AT max ) at low water temperatures. In study 1, AT max , heart rate (HR) and cutaneous blood cell velocity were measured in 13 non-apnoea-trained males during apnoeic face immersion in 0, 10, 20 and 33• C water and room air (AIR). In study 2, six males were measured during non-apnoeic face immersion in 0, 10 and 33• C water for ventilation (V E ), respiratory exchange ratio (RER), HR and oxygen consumption (V O 2 ), as well for end-tidal partial pressures of oxygen (P ET,O 2 ) and carbon dioxide (P ET,CO 2 ). Results indicated that the AT max of 30.7 s (S.D. 7.1 s) at 0• C (P < 0.001) and 48.2 s (S.D. 16.0 s) at 10 • C (P < 0.05) were significantly shorter than that of ∼58 s in AIR or 33• C. During apnoea at 0, 10, 20 and 33 • C, both the deceleration of HR (P < 0.05) and peripheral vasoconstriction (P < 0.05), as well as the peak HR at 0• C (P = 0.002) were significantly greater than in AIR. At 0 • C in comparison with 33• C, non-apnoeic face immersions gave peaks inV E (P = 0.039), RER (P = 0.025), P ET,O 2 (P = 0.032) and HR (P = 0.011), as well as lower minimum values for P ET,CO 2 (P = 0.033) and HR (P = 0.002). WithV O 2 as the covariate, ANCOVA showed thatV E remained significantly greater (P = 0.003) at lower water temperatures. In conclusion, during face immersion at 10• C and below, there is a non-metabolic, neurally mediated cold shock-like response that shortens apnoea, stimulates ventilation and predominates over the oxygen conserving effects of the dive response.

show abstract

“…The respiratory drive evoked by cold water immersion can reduce the maximum breath hold times of normally clothed individuals to less than 10 s (242) and significantly increases the chance of aspirating water and drowning during the first few minutes of immersion. The hypocapnia probably accounts for the tetany, disorientation, and clouding of consciousness observed with cold water immersion (5,53,104). Furthermore, there is an inspiratory shift in endexpiratory lung volume which can result in the occurrence of tidal breathing within 1 L of total lung capacity (141,241).…”

Section: Short-term Water Immersionmentioning

confidence: 99%

Cold Stress Effects on Exposure Tolerance and Exercise Performance

Castellani

Tipton

2015

Comprehensive Physiology

108

115

View full text Add to dashboard Cite

Cold weather can have deleterious effects on health, tolerance, and performance. This paper will review the physiological responses and external factors that impact cold tolerance and physical performance. Tolerance is defined as the ability to withstand cold stress with minimal changes in physiological strain. Physiological and pathophysiological responses to short-term (cold shock) and long-term cold water and air exposure are presented. Factors (habituation, anthropometry, sex, race, and fitness) that influence cold tolerance are also reviewed. The impact of cold exposure on physical performance, especially aerobic performance, has not been thoroughly studied. The few studies that have been done suggest that aerobic performance is degraded in cold environments. Potential physiological mechanisms (decreases in deep body and muscle temperature, cardiovascular, and metabolism) are discussed. Likewise, strength and power are also degraded during cold exposure, primarily through a decline in muscle temperature. The review also discusses the concept of thermoregulatory fatigue, a reduction in the thermal effector responses of shivering and vasoconstriction, as a result of multistressor factors, including exhaustive exercise.

show abstract

Respiratory and other responses in subjects immersed in cold water

Cited by 38 publications

References 0 publications

Global REACH 2018: The influence of acute and chronic hypoxia on cerebral haemodynamics and related functional outcomes during cold and heat stress

Global REACH 2018: The influence of acute and chronic hypoxia on cerebral haemodynamics and related functional outcomes during cold and heat stress

Human face‐only immersion in cold water reduces maximal apnoeic times and stimulates ventilation

Cold Stress Effects on Exposure Tolerance and Exercise Performance

Contact Info

Product

Resources

About