Frostbite Injuries in the Austrian Alps: A Retrospective 11-Year National Registry Study

Abstract

Objectives:

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.

Methods:

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.

Results:

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).

Conclusions:

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.

Introduction

Frostbite is a cold thermal injury occurring when tissues are exposed to temperatures below their freezing point (i.e., −0.55°C) for a sustained time period (Gross and Moore, 2012). Hands and feet account for 90% of the frostbite injuries reported in Norway, Finland, Canada, and the United States (Reamy, 1998; Imray et al., 2009), but also the face (e.g., nose, chin, earlobes, cheeks, and lips), buttocks (e.g., sitting on metal seats), and genital tract (e.g., in joggers and Nordic skiers) can be affected (Gross and Moore, 2012). The severity of frostbite injuries ranges from superficial lesions with complete resolution to deep and extended tissue damage, leading to limb amputation with its functional consequences. Injury severity depends on ambient factors, including absolute temperature, wind chill, humidity, and exposure time, and patient risk factors such as age, smoking status, alcohol consumption, pre-existing vascular disease, or neuropathies (Handford et al., 2014). Adults aged 30–49 years are most frequently affected by frostbite injuries (Reamy, 1998; Imray et al., 2009), most likely due to the cold exposure during winter sports such as skiing, hiking, and mountain and ice climbing (Hallam et al., 2010).

More than a quarter of the Alps are situated in Austria (28.7%), and 65.5% of Austria's land mass is located in the Alpine terrain; more than 50% of Austria's population (4,000,000 inhabitants) live in mountain regions (Onida et al., 2009). The western states of Austria, namely Vorarlberg, Tyrol and Salzburg, have 1,680,000 inhabitants. Tyrol is a mountain region in Austria with ∼745,000 inhabitants plus about 10 million tourists per year (58% of them during the winter), since the region is known for its numerous possibilities to practice winter sports.

The aim of this National Registry study was to reveal the incidence of frostbite injuries in the Austrian Alps and to analyze the cases admitted to Innsbruck Medical University Hospital. This hospital is a tertiary trauma care center and the referral center for all severe medical cases in the western states of Austria. Furthermore, risk factors for frostbite injuries were identified to optimize prevention and treatment.

Methods

The study was approved by the Institutional Review Board of Innsbruck Medical University Hospital and the Austrian Data Protection Authority. It was registered with Clinical Trials (NCT03405467). In Austria, data on every medical emergency occurring in the mountains are recorded by the Austrian Alpine Police and stored in the National Registry of Alpine Accidents kept by the Austrian Board for Alpine Safety (Österreichisches Kuratorium für alpine Sicherheit). This National Registry was screened for frostbite injuries from January 1, 2005, to December 31, 2015. Furthermore, the clinical information system used by the Innsbruck Medical University Hospital, the referral center for critical medical cases in western Austria, was searched for patients discharged with a diagnosis of frostbite (ICD 10 codes T33.0–T35.7) during the study period. Out-of-hospital and in-hospital patient data were matched and merged, where possible. Patients were not involved and not interviewed in the study protocol.

Using a case report form (Supplementary Data; Supplementary Data are available online at www.liebertpub.com/ham), the following data were retrieved: patient sex and age, date and time of event and rescue alert, ambient temperature, wind speed, weather forecast, altitude at which the event occurred, duration of cold exposure, body site affected by frostbite, circumstances leading to frostbite, time delay and first treatment before arrival of professional emergency medical service (EMS), core body temperature at EMS arrival, initial severity grading of the frostbite injury, initial treatment administered by EMS, treatment during hospital transport, mission characteristics (air/terrestrial rescue), time of arrival at hospital, core body temperature on hospital arrival, in-hospital treatment, final assessment of severity, additional injuries, active rewarming in the case of hypothermia, patient risk factors, and outcome at hospital discharge and after 6 months.

Results

For the period from January 1, 2005, to December 31, 2015, the National Registry of Mountain Accidents in Austria contained 74,609 alpine accidents with 114,595 injured persons. Thirty-one cases of frostbite injury of any degree incurred in the Austrian Alps were documented during the study period, 18 (58%) of them in the western states of Austria, which is a potential referral area for Innsbruck Medical University Hospital (Supplementary Fig. S1). The hospital registry for the same period shows a total of 112 patients admitted to Innsbruck Medical University Hospital suffering from frostbite injuries, six of whom suffered these injuries in a mountainous environment. Only in one case could the out-of-hospital data be matched with the in-hospital data, whereas in five cases only in-hospital data were existent (Fig. 1).

FIG. 1.

Selection of frostbite cases.

The incidence of frostbite remained constant over the study period and was ∼0.07 per 100,000 for the overall Austrian mountainous regions (Fig. 2), compared with 0.1 per 100,000 per year in Austria's western states.

FIG. 2.

Frostbite injuries per year, in the Austrian Alps (n = 31, 2005–2015).

National registry data

The National Registry data show 6 (19.4%) of the 31 patients to be female. Mean patient age (±standard deviation) was 41.6 (±17.5) years, range 20–90 years. Most frostbite injuries occurred while hiking (41.9%) or mountaineering (25.8%) (Table 1) and most frequently during winter, although frostbite was registered throughout the entire year (Fig. 3).

FIG. 3.

Incidence of frostbite injuries across the year in the Austrian Alps (n = 31, 2005–2015).

Table 1.

Demographic Data and Circumstances Leading to Frostbite Injuries in the Austrian Alps; Standard Deviation (n = 31, 2005–2015)

	Nationwide frostbite injuries, n = 31 (%)
Female gender, n (%)	6 (19.4)
Mean age ± SD	41.58 ± 17.5
Country of origin
Austria	13 (41.9)
Germany	7 (22.6)
Poland	4 (12.9)
Slovakia	3 (9.7)
Czech Republic	1 (3.2)
Romania	1 (3.2)
New Zealand	1 (3.2)
Brazil	1 (3.2)
Altitude (m above sea level)
<1500 m	10 (32.3)
1500–2500 m	14 (45.2)
>2500 m	7 (22.6)
Activity
Hiking	13 (41.9)
Ski touring	0
Mountaineering	8 (25.8)
Skiing	1 (3.2)
Other	9 (30)

SD, standard deviation.

Most of the frostbite injuries occurred over 1500 m (67.8%). Twenty-one (67.7%) cases occurred at night, two (6.5%) cases at dusk, and three (9.7%) cases during the day. Twelve (38.7%) accidents happened during an ascent and six (19.4%) while making a descent. In six (19.4%) cases, the direction was unclear. The weather was calm in 8 (25.8%) cases, sunny in 3 (9.7%), and cloudy in 10 (32.3%) cases. Overcast weather or snowfall was the main weather condition in three (9.7%) and blizzard in seven (22.6%) accidents. Only two accidents (6.5%) occurred when accompanied by a tour guide. Rescue was terrestrial in 10 (32.3%) cases, by helicopter in 12 (38.7%) cases, and in 7 (22.6%) cases it involved a combination of terrestrial and air rescue. Two cases were not rescued by a rescue organization. The injury severity of frostbite patients assessed by the emergency physician and graded according to the National Advisory Committee on Aeronautics (NACA) severity score is shown in Figure 4. Twenty-two (71%) frostbite cases were attributed to prolonged exposure to cold (Fig. 5). The degree of frostbite injury is unknown.

FIG. 4.

Severity of frostbite injuries suffered in the Austrian Alps according to the NACA severity score. NACA 1 + 2: mildly injured; NACA 3: moderately injured; NACA 4–6: severe and life-threatening injury (n = 31, 2005–2015). NACA, National Advisory Committee on Aeronautics.

FIG. 5.

Circumstances leading to frostbite injuries in the Austrian Alps (n = 31, 2005–2015).

Mean age of frostbite patients in western Austria was 37.1 (±13.8) years. The number of tourists who suffered a frostbite injury was 19.7% higher than in the rest of Austria (77.8% vs. 58.1%). Compared with the nationwide data, twice as many frostbite injuries occurred over 2500 m above sea level (44.4% vs. 22.6%); 38.9% vs. 25.8% of frostbite injuries occurred while ski touring or mountaineering.

Innsbruck data

The six cases treated at Innsbruck Medical University Hospital largely involved fingers (50%) and toes (40.4%, Supplementary Table S1). Two-thirds of these cases were classified as grade II frostbite injuries (Supplementary Table S1). In one case, concomitant accidental hypothermia (core body temperature 33.5°C) was diagnosed.

Data on in-hospital management were available for six patients, and their treatment was largely uniform: five patients received alprostadil (a prostaglandin E1 analog) at a dose of 40 mcg per day intravenous (iv), for 21 days, acetylsalicylic acid 100 mg per day orally (po), and enoxaparin subcutaneous (sc) 80–160 mg per day. None of the patients received a tissue-type plasminogen activator. Three patients received amlodipine 10 mg per day and three patients were given antibiotic therapy (i.e., cefuroxime or amoxicillin/clavulanic acid). All patients were treated with analgesics (i.e., nonsteroidal anti-inflammatory drugs, acetaminophen, and/or opioids). In one case, the first toe had to be amputated bilaterally.

Discussion

Frostbite injuries in the Austrian Alps are rare. With an incidence of ∼0.07/100,000, three to four clinically relevant cases of frostbite occur on a yearly basis. Men are more at risk for frostbite than are women. Fingers and toes are at highest risk for frostbite. The incidence of frostbite in Austria is considerably lower than that reported by a Swedish study (1.5/100,000 per year) (Brandstrom et al., 2014). However, our analysis included only frostbite injuries occurring in the mountains, while the Swedish study also comprised urban and suburban cases. Moreover, Sweden is located further north than Austria, and winter temperatures in Scandinavia tend to be considerably lower. Our results reflect a fairly constant incidence over the years. Only in 2010 was there an increase in frostbite injuries mainly due to one single event where three persons suffered severe frostbite injuries and subsequently died in a blizzard. This constancy of incidence stands in contrast to the increase in outdoor activities undertaken in the mountains over recent years (Thole, 2004). Better equipment and greater awareness, including better preparation for the outdoor activity, might prevent an increase in frostbite injuries (Hall et al., 2010; Cutter, 2015; Osetinsky et al., 2017). Moreover, Austria has one of the highest helicopter emergency medical service densities worldwide, which may ensure fast evacuation and transportation out of Alpine environments.

In our analysis, we were able to confirm the finding made by previous studies (Cauchy et al., 2001; Harirchi et al., 2005; Brandstrom et al., 2014), clearly showing a male predominance of frostbite injuries, possibly due to stronger male risk-taking behavior. Of the frostbite injuries 50% affected one or more fingers and 40% the toes. Most frostbite cases in our study were related to prolonged exposure to cold due to exhaustion, change in weather conditions, or loss of orientation. This demonstrates that with proper preparation for an outdoor activity, including realistic estimation of the physical demands in relation to the person's abilities, detailed planning of the tour and clothing adapted to the forecasted weather can prevent many frostbite injuries.

Clearly, our study has limitations. First, some frostbite cases might have been missed, mainly because of the retrospective nature of the study. Second, in-hospital data were available only from Innsbruck Medical University Hospital, being the referral center for critically ill patients in western Austria. According to National Registry data, 18 (58%) cases occurred in western Austria and could have been transferred to Innsbruck Medical University Hospital. There are two possibilities for the poor matching between the National Registry and the in-hospital data: (1) frostbite injuries were not severe enough to send the patients to the referral center, Innsbruck Medical University Hospital and (2) inconsistencies in the data did not allow the out-of-hospital and the in-hospital data to be matched. Third, particularly patients from eastern Austria might have been treated in other hospitals. Fourth, patients might have reached a hospital without the help of a rescue organization, or they might never have sought medical advice for mild frostbite injuries, thus not triggering an Alpine Police response. We assume that the number of unreported cases includes mostly mild frostbite and might be several times higher than the reported number. Finally, the case report forms remained incomplete due to missing data, limiting a complete analysis of out-of-hospital and in-hospital data.

Conclusions

Severe frostbite injuries in the Austrian Alps are rare. With an incidence of ∼0.07/100,000, three to four clinically relevant cases of frostbite occur on a yearly basis. Men are more at risk for frostbite than are women. Fingers and toes are at highest risk for frostbite. Proper preparation for the outdoor activity and cold-protective gear could prevent most frostbite injuries.

Footnotes

Acknowledgments

We would like to thank Andreas Würtele and Dagmar Walter of the Österreichisches Kuratorium für Alpine Sicherheit (Austrian Alpine Police database), Hans Ebner of the Austrian Alpine Police as well as all contributing police officers for the provision of data.

Author Disclosure Statement

No competing financial interests exist.

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