High Altitude Medicine & Biology

Frostbite is a cold injury mostly affecting the extremities. The objective of this study was to reveal the incidence of frostbite injuries in the Austrian Alps, to search for frostbite risk factors, and thereby optimize prevention and treatment.

Out-of-hospital data in the National Registry of Alpine Accidents from January 1, 2005, to December 31, 2015, were screened for frostbite injuries. Cases in the registry were merged with clinical data from the major trauma center in western Austria, Innsbruck Medical University Hospital, and statistically analyzed.

Documented in the National Registry are 114,595 injured persons in the 11-year study period. Thirty-one frostbite cases were documented nationwide, 18 (58%) of which occurred in the western states of Austria and were therefore potentially referred to the Innsbruck Medical University Hospital. Six (19.6%) patients were female. Frostbite was almost exclusively related to fingers and toes (90% of cases).

Frostbite injuries in the Austrian Alps are rare. With an incidence of 0.07/100,000, three to four clinically relevant frostbite injuries occur annually. Men are at greater risk for frostbite injuries than women. Fingers and toes are at greatest risk. Proper preparation of outdoor activities and cold-protective gear can help prevent frostbite injuries.

To determine whether 2 days of staging at 2500–3500 m, combined with either high or low physical activity, reduces acute mountain sickness (AMS) during subsequent ascent to 4300 m.

Three independent groups of unacclimatized men and women were staged for 2 days at either 2500 m (n = 18), 3000 m (n = 16), or 3500 m (n = 15) before ascending and living for 2 days at 4300 m and compared with a control group that directly ascended to 4300 m (n = 12). All individuals departed to the staging altitudes or 4300 m after spending one night at 2000 m during which they breathed supplemental oxygen to simulate sea level conditions. Half in each group participated in ∼3 hours of daily physical activity while half were sedentary. Women accounted for ∼25% of each group. AMS incidence was assessed using the Environmental Symptoms Questionnaire. AMS was classified as mild (≥0.7 and <1.5), moderate (≥1.5 and <2.6), and severe (≥2.6).

While staging, the incidence of AMS was lower (p < 0.001) in the 2500 m (0%), 3000 m (13%), and 3500 m (40%) staged groups than the direct ascent control group (83%). After ascent to 4300 m, the incidence of AMS was lower in the 3000 m (43%) and 3500 m (40%) groups than the 2500 m group (67%) and direct ascent control (83%). Neither activity level nor sex influenced the incidence of AMS during further ascent to 4300 m.

Two days of staging at either 3000 or 3500 m, with or without physical activity, reduced AMS during subsequent ascent to 4300 m but staging at 3000 m may be recommended because of less incidence of AMS.

To compare a program based on intermittent hypoxia–hyperoxia training (IHHT) consisting of breathing hypoxic–hyperoxic gas mixtures while resting to a standard exercise-based rehabilitation program with respect to cardiorespiratory fitness (CRF) in older, comorbid cardiac outpatients.

Thirty-two cardiac patients with comorbidities were randomly allocated to IHHT and control (CTRL) groups. IHHT completed a 5-week program of exposure to hypoxia–hyperoxia while resting, CTRL completed an 8-week tailored exercise program, and participants in the CTRL were also exposed to sham hypoxia exposure. CRF and relevant hematological biomarkers were measured at baseline and after treatment in both groups.

After intervention, CRF in the IHHT group was not significantly different (n = 15, 19.9 ± 6.1 mlO₂ minutes⁻¹ kg⁻¹) compared with the CTRL group (n = 14, 20.6 ± 4.9 mlO₂ minutes⁻¹ kg⁻¹). CRF in IHHT increased significantly from baseline (6.05 ± 1.6 mlO₂ minutes⁻¹ kg⁻¹), while no difference was found in CTRL. Systolic and diastolic blood pressures were not significantly different between groups after treatment. Hemoglobin content was not significantly different between groups. Erythrocytes and reticulocytes did not change pre/post interventions in both experimental groups.

IHHT is safe in patients with cardiac conditions and common comorbidities and it might be a suitable option for older patients who cannot exercise. A 5-week IHHT is as effective as an 8-week exercise program in improving CRF, without hematological changes. Further studies are needed to clarify the nonhematological adaptations to short, repeated exposure to normobaric hypoxia–hyperoxia.

We sought to characterize the mental health morbidity associated with avalanche rescue, and to generate hypotheses as to how such morbidity may be mitigated.

Avalanche first responders were recruited through online advertisements, social media, direct outreach, and e-mail solicitation. Thirteen subjects were selected for inclusion. Each subject participated in a semistructured interview. Transcripts were coded and thematically analyzed.

Themes identified from interviews fell into three broad categories: long-term effects of rescue participation, assessments of psychological support, and recommendations for change. Symptoms of substance use disorder, depression, anxiety, panic, acute stress disorder, and posttraumatic stress disorder were evident in the interviews, as was evidence of adverse effects on subjects' personal relationships. Many respondents described a deficiency of formal psychological support for avalanche first responders, often limited to after-action debriefs of varying effectiveness. Nevertheless, subjects who received high-quality professional psychological support considered it helpful. Participants' suggestions for improvement focused on formalizing preincident psychological preparation and postincident support.

Avalanche responders may experience long-lasting, work-related psychological effects. There is a paucity of effective psychological preparation and support for this population of first responders. Formal psychological support is positively received when available. Further study is required to evaluate particular interventions in this specific population.

High-altitude (HA) pregnancies have been associated with decreased glucose levels and increased insulin sensitivity versus sea level. Our objective was to determine if the prevalence of gestational diabetes mellitus (GDM) and the impact of demographic characteristics on GDM diagnosis differed at moderate altitude (MA) versus HA.

Using a retrospective cohort design, we compared women living at HA (>8250 ft) and MA (4000–7000 ft) during pregnancy. Exclusion criteria were as follows: multiple gestation, preexisting diabetes, unavailable GDM results, or relocation from a different altitude during pregnancy. GDM diagnosis was determined using Carpenter and Coustan criteria. Data were compared by t-test (continuous variables) or chi-squared tests (categorical variables). Univariate, multivariate, and stepwise regression models were used to assess the impact of various factors on GDM prevalence.

There was no difference in GDM prevalence between altitudes in these populations; the relationship between altitude and GDM was nonsignificant in all regression analyses. At MA, maternal age, Hispanic ethnicity, body mass index (BMI), and gestational age (GA) at testing increased GDM incidence in univariate analyses. At HA, maternal age, Hispanic ethnicity, and multiparity increased GDM incidence in univariate analyses.

While GDM prevalence did not differ between MA and HA, the impact of maternal demographic characteristics on GDM risk varied by altitude group. Higher BMI and greater GA at testing increased the incidence of GDM at MA, but not at HA. Multiparity had an effect at HA, but not MA. These differences may represent subtle differences in glucose metabolism at HA.

Clinical studies have shown that oral vitamin C supplementation can reduce serum uric acid levels in multiple populations and may also improve acute mountain sickness. However, it is unclear whether this protocol can improve high-altitude hyperuricemia. Therefore, we aimed to evaluate the role of vitamin C supplementation on high-altitude hyperuricemia.

A preliminary prospective control study was performed in 2015. Young male army recruits (n = 66), who had recently arrived on the Tibetan Plateau for the first time, were recruited for study I. Subjects were assigned to either the vitamin C group, who took an oral daily dose of 500 mg vitamin C for 1 month, or the blank control group, who had no intervention. The levels of serum uric acid, serum creatinine, and blood urea nitrogen were monitored at baseline and at the end of 1 month. In a second study II in 2016 (n = 120), the effect of 500 mg/d vitamin C on high-altitude hyperuricemia was compared with 75 IU/d of vitamin E.

In study I, the level of serum uric acid at 1 month was significantly higher than at baseline (436.1 ± 79.3 μmol/L vs. 358.0 ± 79.8 μmol/L, p < 0.001) and the prevalence of hyperuricemia was also significantly higher (63.6% [95% confidence interval, CI: 52.0%–75.2%] vs. 19.7% [95% CI: 10.1%–29.3%], p < 0.001). Both the level of serum uric acid (411.5 ± 74.2 μmol/L vs. 460.8 ± 54.8 μmol/L, p = 0.003) and the prevalence of hyperuricemia (48.5% [95% CI: 31.4%–65.6%] vs. 78.8% [95% CI: 64.9%–92.7%], p = 0.020) were significantly lower in the vitamin C group than in the blank control group. In study II, the levels of serum uric acid and the frequency of hyperuricemia also increased over 1 month and were similar in the vitamin C and the vitamin E groups at both baseline and 1 month (p > 0.05). The change in serum uric acid was positively correlated with both the changes in serum creatinine (r = 0.599, p < 0.001) and blood urea nitrogen (r = 0.207, p = 0.005).

These findings indicate that healthy young men develop an increase in serum uric acid within a month of moving from low to high altitude. Oral vitamin C supplementation can safely reduce this increase at a low cost.