The effect of exercise-induced elevation in core temperature on cold-induced vasodilatation response in toes

Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Frostbite: 2024 Update

The Wilderness Medical Society convened an expert panel to develop a set of evidence-based guidelines for the prevention and treatment of frostbite. We present a review of pertinent pathophysiology. We then discuss primary and secondary prevention measures and therapeutic management. Recommendations are made regarding each treatment and its role in management. These recommendations are graded on the basis of the quality of supporting evidence and balance between the benefits and risks or burdens for each modality according to methodology stipulated by the American College of Chest Physicians. This is an updated version of the guidelines published in 2019.

Expert consensus on the prevention, diagnosis and treatment of cold injury in China, 2020

Cold injury refers to local or systemic injury caused by a rapid, massive loss of body heat in a cold environment. The incidence of cold injury is high. However, the current situation regarding the diagnosis and treatment of cold injury in our country is not ideal. To standardize and improve the level of clinical diagnosis and treatment of cold injury in China, it is necessary to make a consensus that is practical and adapted to the conditions in China. We used the latest population-level epidemiological and clinical research data, combined with relevant literature from China and foreign countries. The consensus was developed by a joint committee of multidisciplinary experts. This expert consensus addresses the epidemiology, diagnosis, on-site emergency procedures, in-hospital treatment, and prevention of cold injury.

Effects of cold exposure discontinuation on finger cold-induced vasodilation of older retired Korean female divers 'Haenyeos'

The purpose of the present study was to investigate the effects of cold exposure discontinuation on local cold tolerance of older retired female haenyeos in Korea. A total of 30 older women participated in this study: older retired haenyeos (89 ± 4 y in age, N = 10), active haenyeos (current divers) (75 ± 4 y, N = 10), and age-matched non-divers (75 ± 6 y, N = 10). Our criterion for local cold tolerance was cold-induced vasodilation (CIVD) of the finger. Active haenyeos showed greater local cold tolerance in terms of higher minimum temperature of the left finger during immersion and recovery than the other two groups (P < 0.05). Furthermore, active haenyeos showed higher skin temperatures of the right finger and left foot as well (P < 0.05). Older retired haenyeos displayed the second best minimum finger temperature both during immersion and during recovery (15 min and 20 min), whereas their local cold tolerance was evaluated as inferior to active haenyeos and the age-matched non-divers in CIVD frequency, finger pain sensation, thermal comfort, and finger temperature during the earlier period of recovery (5 min and 10 min). These results suggested that older retired haenyeos' cold tolerance in their extremities disappeared in terms of finger temperature in their initial recovery periods, but that they might still retain cold adaptation in terms of minimum finger temperature or later recovery responses, even though the attributes were not marked as much as those of active haenyeos.

A 4-year follow-up of non-freezing cold injury with cold allodynia and neuropathy in 26 naval soldiers

Background and aims Non-freezing cold injuries (NFCI), which typically may occur in military personnel, may result from exposure to cold, at temperatures around 0 °C or above, and worsened by wind and moisture. The injury is due to cooling but not freezing of tissue like in frostbite. NFCI may result in in chronic neuropathy and cold hypersensitivity. A recent retrospective study of small-and large fibres has suggested that NFCI results in neuropathic pain due to a sensory neuropathy and question a longitudinal study to verify a possible observation of improvement of NFCI over time. The present study is a 4-year follow-up investigation of large - and small-fibre function in 26 naval cadets and officers who were exposed to cold injury during the same military expedition. Methods The 26 soldiers were investigated clinically (with investigation of motor function, reflexes, sensibility), with nerve conduction studies (NCS) of major nerves in upper- and lower extremity, small fibre testing (QST, measurement of thermal thresholds), measurements of subcutaneous fat tissue and maximal O2 uptake. Investigations found place 2 months following the actual military expedition, with follow-up investigations of affected soldiers at 6-12 months and up to 3-4 years. In order to elucidate possible mechanisms (disinhibition of cold pain by myelinated nerve fibres) of cold allodynia, cold pain thresholds were measured following an ischemic block of conduction of large and small myelinated nerve fibres. Results Of 26 soldiers, 19 complained of numbness in feet and a large majority of 16 of cold hypersensitivity 2 months following injury. There were significant alterations of both large- and small-fibre function, indicating a general large- and small-fibre neuropathy. The most prominent finding was a pronounced cold allodynia, inversely correlated with the amount of subcutaneous fat. During the first year, results of NCS and thermal testing gradually normalized in most. Seven soldiers developed chronic symptoms in the form of cold hypersensitivity and with findings of cold allodynia, which was not further enhanced, but abolished following block of conduction of myelinated nerve fibres. Seven soldiers were free of symptoms from that start of the investigation, probably because they had been more eager to keep their legs moving during the exposure to cold. Conclusions Of a total of 26 soldiers, only seven developed chronic symptoms of cold hypersensitivity, corresponding to the finding of cold allodynia by thermal testing. The cold allodynia may not be explained by disinhibition of cold pain by myelinated fibres as in healthy subjects. A large majority recovered from an initial large-and small fibre neuropathy, demonstrating that recovery from NFCI may occur. Implications Although large-and small fibre neuropathy may be restored following cold injury, there is a risk of a permanent and disabling cold hypersensitivity, corresponding to the findings of cold allodynia. It is of uttermost importance to secure military personnel from the risk of cold injuries. It seems important to avoid immobilisation of extremities during exposure to cold.

Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Frostbite: 2019 Update

The Wilderness Medical Society convened an expert panel to develop a set of evidence-based guidelines for prevention and treatment of frostbite. We present a review of pertinent pathophysiology. We then discuss primary and secondary prevention measures and therapeutic management. Recommendations are made regarding each treatment and its role in management. These recommendations are graded on the basis of the quality of supporting evidence and balance between the benefits and risks or burdens for each modality according to methodology stipulated by the American College of Chest Physicians. This is an updated version of the guidelines published in 2014.

Cold-induced vasodilation responses before and after exercise in normobaric normoxia and hypoxia

PURPOSE

Cold-induced vasodilation (CIVD) is known to protect humans against local cold injuries and improve manual dexterity. The current study examined the effects of metabolic heat production on cold-induced vasodilation responses in normobaric hypoxia and normoxia.

METHODS

Ten participants immersed their non-dominant hand into 5 °C water for 15 min. Minimum finger temperature (T_min), maximum finger temperature (T_max), onset time, amplitude, and peak time were measured before and after exercise under normoxia (21% O₂) and two levels of normobaric hypoxia (17% O₂ and 13% O₂).

RESULTS

Neither T_min nor amplitude was affected by hypoxia. However, T_max was significantly decreased by hypoxia while reduction in onset time and peak time trended towards significance. T_min, T_max, and amplitude were significantly higher during post-exercise CIVD than pre-exercise CIVD.

CONCLUSION

The CIVD response may be negatively affected by the introduction of hypoxia whereas metabolic heat production via exercise may counteract adverse effects of hypoxia and improve CIVD responses.

Koroška 8000 Himalayan expedition: digit responses to cold stress following ascent to Broadpeak (Pakistan, 8051 m)

PURPOSE

Cold-induced vasodilatation (CIVD) is a peripheral blood flow response, observed in both the hands and feet. Exercise has been shown to enhance the response, specifically by increasing mean skin temperatures (T_sk), in part due to the increased number of CIVD waves. In contrast, hypobaric hypoxia has been suggested to impair digit skin temperature responses, particularly during subsequent hand rewarming following the cold stimulus. This study examined the combined effect of exercise and hypobaric hypoxia on the CIVD response. We compared the CIVD responses in the digits of both the hands and feet of a team of alpinists (N = 5) before and after a 35-day Himalayan expedition to Broadpeak, Pakistan (8051 m).

METHODS

Five elite alpinists participated in hand and foot cold water immersion tests 20 days before and immediately upon return from their expedition.

RESULTS

The alpinists summited successfully without supplemental oxygen. Post-expedition, all alpinists demonstrated higher minimum T_sk in their hands (pre: 9.9 ± 1.1, post: 10.1 ± 0.7 °C, p = 0.031). Four alpinists had either greater CIVD waves, and, consequently, higher mean T_sk in their hands, or higher recovery temperatures (pre: 26.0 ± 5.5 °C post: 31.0 ± 4.1 °C, p = 0.052), or faster rewarming rate (pre: 2.6 ± 0.5 °C min^-1 post: 3.1 ± 0.4 °C min^-1,p = 0.052). In the feet, the responses varied: 1/5 had higher wave amplitudes and 1/5 had higher passive recovery temperatures, whereas 3/5 had lower mean toe temperatures during cold exposure.

CONCLUSIONS

The results of the cold stress test suggest after a 35-day Himalayan expedition, alpinists experienced a slight cold adaptation of the hands, but not the feet.

Endurance exercise causes adverse changes in some hematological and physiobiochemical indices in ponies under high altitude stress condition

The ponies have immense relevance for logistic support for civil population and troops in hilly and high altitude areas. There is no information on specific biomarkers of endurance performance under high altitude stress condition, which could be supportive in the identification of elite ponies for deployment at high altitude. Therefore, the present study was conducted to evaluate the physiological responses, hematological, biochemical, metabolic, and antioxidant biomarker during endurance exercise in ponies at high altitude. For this study, total 5 mares were put on endurance exercise at 4–6 m/sec speed for 30 min on 30 m track situated at 3,500 m altitude for 28 days period. The result showed a significant change in physiological responses, and some hematological, biochemical, metabolic and antioxidant parameters viz. glutathione peroxidase, creatinine kinase-MB, lactic acid, total protein, glucose, hexokinase, cortisol, and interleukin-6 level at different phase of endurance exercise. In conclusion, this study showed the alteration in physiological responses and some hematological and physio-biochemical metabolic parameters during the endurance exercise. Hence, these parameters could be considered as biomarkers for evaluation of endurance performance in ponies at high altitude before putting them under load carrying deployment.

Role of cyclooxygenase in the vascular responses to extremity cooling in Caucasian and African males

NEW FINDINGS

What is the central question of this study? Compared with Caucasians, African individuals are more susceptible to non-freezing cold injury and experience greater cutaneous vasoconstriction and cooler finger skin temperatures upon hand cooling. We investigated whether the enzyme cyclooxygenase is, in part, responsible for the exaggerated response to local cooling. What is the main finding and its importance? During local hand cooling, individuals of African descent experienced significantly lower finger skin blood flow and skin temperature compared with Caucasians irrespective of cyclooxygenase inhibition. These data suggest that in young African males the cyclooxygenase pathway appears not to be the primary reason for the increased susceptibility to non-freezing cold injury. Individuals of African descent (AFD) are more susceptible to non-freezing cold injury (NFCI) and experience an exaggerated cutaneous vasoconstrictor response to hand cooling compared with Caucasians (CAU). Using a placebo-controlled, cross-over design, this study tested the hypothesis that cyclooxygenase (COX) may, in part, be responsible for the exaggerated vasoconstrictor response to local cooling in AFD. Twelve AFD and 12 CAU young healthy men completed foot cooling and hand cooling (separately, in 8°C water for 30 min) with spontaneous rewarming in 30°C air after placebo or aspirin (COX inhibition) treatment. Skin blood flow, expressed as cutaneous vascular conductance (as flux per millimetre of mercury), and skin temperature were measured throughout. Irrespective of COX inhibition, the responses to foot cooling, but not hand cooling, were similar between ethnicities. Specifically, during hand cooling after placebo, AFD experienced a lower minimal skin blood flow [mean (SD): 0.5 (0.1) versus 0.8 (0.2) flux mmHg^-1 , P < 0.001] and a lower minimal finger skin temperature [9.5 (1.4) versus 10.7 (1.3)°C, P = 0.039] compared with CAU. During spontaneous rewarming, average skin blood flow was also lower in AFD than in CAU [2.8 (1.6) versus 4.3 (1.0) flux mmHg^-1 , P < 0.001]. These data provide further support that AFD experience an exaggerated response to hand cooling on reflection this appears to overstate findings; however, the results demonstrate that the COX pathway is not the primary reason for the exaggerated responses in AFD and increased susceptibility to NFCI.

A Descriptive Study of Hot Aches: a Previously Unreported Winter Climbing Phenomenon

BACKGROUND

Hot aches, also known as the screaming barfies in North America, are a recognised phenomenon amongst winter climbers, assumed to be triggered by the reperfusion of cold peripheries which then rapidly progresses to a systemic vasodilatory syndrome. Symptoms experienced in the hands include pain, numbness and throbbing followed by systemic symptoms such as nausea, irritability, dizziness and in extreme cases a transient loss of vision and hearing. Despite being well known amongst the winter climbing community, there are no publications in the scientific literature characterising the hot aches.

METHODS

A survey was posted online at http://www.ukclimbing.com between the dates of 28th September 2014 to 1st December 2014. Data was collected and analysed offline using Microsoft excel.

RESULTS

This is a descriptive epidemiological study of UK winter climbers and their experience of hot aches. We found that hot aches are experienced by 96 % of these climbers. They generally last 1-5 min, and 75 % rate them as being 3-4 (out of 5) on a pain scale. The most common local symptoms are pain (87 %), throbbing (70 %) and tingling (52 %). The most common systemic symptoms are nausea (44 %), irritability (32 %) and dizziness (20 %). Twenty percent of climbers experience hot aches in locations other than their hands.

CONCLUSIONS

The hot aches are a highly predictable and consistent experience for almost all winter climbers. This study has characterised, for the first time, a recognised but previously unreported phenomenon that occurs in extreme winter climbers. The short- and long-term consequences are currently unknown and warrant further investigation.

Cold-induced vasodilation comparison between Bangladeshi and Japanese natives

Background

The human thermoregulation system responds to changes in environmental temperature, so humans can self-adapt to a wide range of climates. People from tropical and temperate areas have different cold tolerance. This study compared the tolerance of Bangladeshi (tropical) and Japanese (temperate) people to local cold exposure on cold-induced vasodilation (CIVD).

Methods

Eight Bangladeshi males (now residing in Japan) and 14 Japanese males (residing in Japan) participated in this study. All are sedentary, regular university students. The Bangladeshi subject’s duration of stay in Japan was 2.50 ± 2.52 years. The subject’s left hand middle finger was immersed in 5 °C water for 20 min to assess their CIVD response (the experiment was conducted in an artificial climate chamber controlled at 25 °C with 50 % RH).

Results

Compared with the Bangladeshi (BD) group, the Japanese (JP) group displayed some differences. There were significant differences between the BD and JP groups in temperature before immersion (TBI), which were 33.04 ± 1.98 and 34.62 ± 0.94 °C, and time of temperature rise (TTR), which were 5.35 ± 0.82 and 3.72 ± 0.68 min, respectively. There was also a significant difference in the time of sensation rise (TSR) of 8.69 ± 6.49 and 3.26 ± 0.97 min between the BD and JP groups, respectively (P < 0.05). Moreover, the JP group showed a quick TTR after finishing immersion.

Conclusions

The Japanese group (temperate) has a higher tolerance to local cold exposure than the Bangladeshi group (tropical) evaluated by the CIVD test.

Wilderness Medical Society practice guidelines for the prevention and treatment of frostbite: 2014 update

The Wilderness Medical Society convened an expert panel to develop a set of evidence-based guidelines for the prevention and treatment of frostbite. We present a review of pertinent pathophysiology. We then discuss primary and secondary prevention measures and therapeutic management. Recommendations are made regarding each treatment and its role in management. These recommendations are graded on the basis of the quality of supporting evidence and balance between the benefits and risks or burdens for each modality according to methodology stipulated by the American College of Chest Physicians. This is an updated version of the original guidelines published in Wilderness & Environmental Medicine 2011;22(2):156-166.

Responses of the hands and feet to cold exposure

An initial response to whole-body or local exposure of the extremities to cold is a strong vasoconstriction, leading to a rapid decrease in hand and foot temperature. This impairs tactile sensitivity, manual dexterity, and muscle contractile characteristics while increasing pain and sympathetic drive, decreasing gross motor function, occupational performance, and survival. A paradoxical and cyclical vasodilatation often occurs in the fingers, toes, and face, and this has been termed the hunting response or cold-induced vasodilatation (CIVD). Despite being described almost a century ago, the mechanisms of CIVD are still disputed; research in this area has remained largely descriptive in nature. Recent research into CIVD has brought increased standardization of methodology along with new knowledge about the impact of mediating factors such as hypoxia and physical fitness. Increasing mechanistic analysis of CIVD has also emerged along with improved modeling and prediction of CIVD responses. The present review will survey work conducted during this century on CIVD, its potential mechanisms and modeling, and also the broader context of manual function in cold conditions.

Qigong Effects on Heart Rate Variability and Peripheral Vasomotor Responses

Population aging is occurring worldwide, and preventing cardiovascular event in older people is a unique challenge. The aim of this study was to examine the effects of a 12-week qigong (eight-form moving meditation) training program on the heart rate variability and peripheral vasomotor response of middle-aged and elderly people in the community. This was a quasi-experimental study that included the pre-test, post-test, and nonequivalent control group designs. Seventy-seven participants (experimental group = 47; control group = 30) were recruited. The experimental group performed 30 min of eight-form moving meditation 3 times per week for 12 weeks, and the control group continued their normal daily activities. After 12 weeks, the interaction effects indicated that compared with the control group, the experimental group exhibited significantly improved heart rate variability and peripheral vasomotor responses.

Prolonged physical inactivity leads to a drop in toe skin temperature during local cold stress

The purpose was to examine the effects of a prolonged period of recumbency on the toe temperature responses during cold-water foot immersion. Ten healthy males underwent 35 days of horizontal bed rest. The right foot of the subjects was assigned as the experimental (EXP) foot. To prevent bed rest-induced vascular deconditioning in the left control foot (CON), a sub-atmospheric vascular pressure countermeasure regimen was applied on the left lower leg for 4 × 10 min every second day. On the first (BR-1) and the last (BR-35) day of the bed rest, subjects performed two 30 min foot immersion tests in 8 °C water, one with the EXP foot and the other with the CON foot. The tests were conducted in counter-balanced order and separated by at least a 15 min interval. At BR-35, the average skin temperature of the EXP foot was lower than at BR-1 (–0.8 °C; P = 0.05), a drop that was especially pronounced in the big toe (–1.6 °C; P = 0.05). In the CON foot, the average skin temperature decreased by 0.6 °C in BR-35, albeit the reduction was not statistically significant (P = 0.16). Moreover, the pressure countermeasure regimen ameliorated immersion-induced thermal discomfort for the CON foot (P = 0.05). Present findings suggest that severe physical inactivity exaggerates the drop in toe skin temperature during local cold stress, and thus might constitute a potential risk factor for local cold injury.

The effect of a sleep high-train low regimen on the finger cold-induced vasodilation response

The present study evaluated the effect of a sleep high-train low regimen on the finger cold-induced vasodilation (CIVD) response. Seventeen healthy males were assigned to either a control (CON; n=9) or experimental (EXP; n=8) group. Each group participated in a 28-day aerobic training program of daily 1-h exercise (50% of peak power output). During the training period, the EXP group slept at a simulated altitude of 2800 meters (week 1) to 3400 m (week 4) above sea level. Normoxic (CIVD(NOR); CON and EXP groups) and hypoxic (CIVD(HYPO); F(I)O(2)=0.12; EXP group only) CIVD characteristics were assessed before and after the training period during a 30-min immersion of the hand in 8°C water. After the intervention, the EXP group had increased average finger skin temperature (CIVD(NOR): +0.5°C; CIVD(HYPO): +0.5°C), number of waves (CIVD(NOR): +0.5; CIVD(HYPO): +0.6), and CIVD amplitude (CIVD(NOR): +1.5°C; CIVD(HYPO): +3°C) in both CIVD tests (p<0.05). In contrast, the CON group had an increase in only the CIVD amplitude (+0.5°C; p<0.05). Thus, the enhancement of aerobic performance combined with altitude acclimatization achieved with the sleep high-train low regimen contributed to an improved finger CIVD response during cold-water hand immersion in both normoxic and hypoxic conditions.

Enhancement of the finger cold-induced vasodilation response with exercise training

Cold-induced vasodilatation (CIVD) is a cyclical increase in finger temperature that has been suggested to provide cryoprotective function during cold exposures. Physical fitness has been suggested as a potential factor that could affect CIVD response, possibly via central (increased cardiac output, decreased sympathetic nerve activity) and/or peripheral (increased microcirculation) cardiovascular and neural adaptations to exercise training. Therefore, the purpose of this study was to investigate the effect of endurance exercise training on the CIVD response. Eighteen healthy males trained 1 h d(-1) on a cycle ergometer at 50% of peak power output, 5 days week(-1) for 4-weeks. Pre, Mid, Post, and 10 days after the cessation of training and on separate days, subjects performed an incremental exercise test to exhaustion (.VO(2peak)) and a 30-min hand immersion in 8 degrees C water to examine their CIVD response. The exercise-training regimen significantly increased .VO(2peak) (Pre: 46.0 +/- 5.9, Mid: 52.5 +/- 5.7, Post: 52.1 +/- 6.2, After: 52.6 +/- 7.6 ml kg(-1) min(-1); P < 0.001). There was a significant increase in average finger skin temperature (Pre: 11.9 +/- 2.4, After: 13.5 +/- 2.5 degrees C; P < 0.05), the number of waves (Pre: 1.1 +/- 1.0, After: 1.7 +/- 1.1; P < 0.001) and the thermal sensation (Pre: 1.7 +/- 0.9, After: 2.5 +/- 1.4; P < 0.001), after training. In conclusion, the aforementioned endurance exercise training significantly improved the finger CIVD response during cold-water hand immersion.