Does modern helicopter construction reduce noise exposure in helicopter rescue operations?

BACKGROUND: During helicopter rescue operations the medical personnel are at high risk for hearing damage by noise exposure. There are two important factors to be taken into account: first, the extreme variability, with some days involving no exposure but other days with extreme exposure; second, the extreme noise levels during work outside the helicopter, e.g. during winch operations. The benefit of modern, less noisier constructions and the consequences for noise protection are still unknown. OBJECTIVES: We estimated the noise exposure of the personnel for different helicopter types used during rescue operations in the Alps and in other regions of the world with special regard to the advanced types like Eurocopter EC 135 to compare the benefit of modern constructions for noise protection with earlier ones. METHODS: The rescue operations over 1 year of four rescue bases in the Alps (Raron and Zermatt in Switzerland; Landeck and Innsbruck in Austria, n = 2731) were analyzed for duration of rescue operations (noise exposure). Noise levels were measured during rescue operations at defined points inside and outside the different aircraft. The setting is according to the European standard (Richtlinie 2003/10/EG Amtsblatt) and to Class 1 DIN/IEC 651. With both data sets the equivalent noise level L(eq8h) was calculated. For comparison it was assumed that all rescue operations were performed with a specific type of helicopter. Then model calculations for noise exposure by different helicopter types, such as Alouette IIIb, Alouette II 'Lama', Ecureuil AS350, Bell UH1D, Eurocopter EC135, and others were performed. RESULTS AND CONCLUSIONS: Depending on modern technologies the situation for the personnel has been improved significantly. Nevertheless noise prevention, which includes noise intermissions in spare time, is essential. Medical checks of the crews by occupational medicine (e.g. 'G20' in Germany) are still mandatory.

Analysis of local drinking water for fecal contamination in Solu-Khumbu / Mt. Everest region, Nepal.

BACKGROUND: To evaluate the drinking water quality in the popular trekking area of Solu-Khumbu Mt. Everest region as a possible source for the high incidence of diarrhea. MATERIAL AND METHODS: Drinking water samples (n = 80) were collected from whatever primary source the locals/tourists used at altitudes 2,608 to 5,180m; and where possible, also from inside households. Samples were analyzed for fecal contamination using the DelAgua Dual Incubator at 37 °C and 44 °C to detect the total and thermotolerant coliform bacteria. The pH, temperature, turbidity, smell, and taste were also registered. RESULTS: No thermotolerant bacteria were found but a significant number of specimens contained many colony forming units (CFU) of total coliform bacteria. Household specimens were more often contaminated compared to the water from the primary source. CONCLUSION: Data indicate a significant secondary contamination when water was handled and stored in unhygienic containers. Health education programs on water hygiene, sanitation, and the safe handling and storage of water needs improvement. It is strongly recommended that drinking water is disinfected using filter systems, UV-light dispensers or halogens (e.g. chlorine), or a combination of two methods. Although cooking is a common disinfection method here, fuel is scarce. Water was generally safer when collected directly from the primary source in a clean container than from a lodge.

Companion Rescue and Risk Management of Trekkers on the Everest Trek, Solo Khumbu Region, Nepal.

BACKGROUND: Trekking to high-altitude locations presents inherent health-related hazards, many of which can managed with specific first aid (FA) training. This study evaluates the trip preparation, FA knowledge, and FA self-assessment of trekkers (organized by tour operators vs. individually planned tours). Data obtained shall be used for specific FA trip preparation and management of emergencies en route for this population. METHODS: A total of 366 trekkers on the Everest Base Camp Trek, Nepal, were interviewed using a questionnaire specifically designed to evaluate their FA knowledge and management of emergencies. Data evaluation was performed using descriptive statistics. RESULTS: A total of 40.5% of trekkers experienced at least one medical incident during their trip, of which almost 50% were due to acute mountain sickness (AMS). There was more AMS in commercially organized groups than in individually planned ones (55% vs. 40%). For more than 50%, no medical care was available during their trip. A total of 80% could answer only 3/21 FA questions completely correctly. Only 1% showed adequate knowledge concerning FA strategies. A total of 70% were willing to enroll in an FA class specialized towards the needs of trekkers. CONCLUSIONS: The importance of high-altitude FA knowledge and trip preparation is widely underestimated. There is an unmet demand amongst trekkers for specific wilderness FA classes.

Variables Influencing the Pressure and Volume of the Pulmonary Circulation as Risk Factors for Developing High Altitude Pulmonary Edema (HAPE).

BACKGROUND: At altitudes above 2500 m, the risk of developing high altitude pulmonary edema (HAPE) grows with the increases in pulmonary arterial pressure. HAPE is characterized by severe pulmonary hypertension, though the incidence and relevance of individual risk factors are not yet predictable. However, the systolic pulmonary pressure (SPAP) and peak in tricuspid regurgitation velocity (TVR) are crucial factors when diagnosing pulmonary hypertension by echocardiography. METHODS: The SPAP and TVR of 27 trekkers aged 20-65 years en route to the Solu Khumbu region of Nepal were assessed. Echocardiograph measurements were performed at Lukla (2860 m), Gorak Shep (5170 m), and the summit of Kala Patthar (5675 m). The altitude profile and the participants' characteristics were also compiled for correlation with the measured data. RESULTS: The results showed a highly significant increase in SPAP and TVR after ascending Kala Patthar. The study revealed a lower increase of SPAP and TVR in the group of older participants, although the respective initial measurements at Gorak Shep were significantly higher for this group. A similar finding occurred in those using Diamox® as prophylaxis. There was an inverse relationship between TVR and SPAP, the peripheral capillary oxygen saturation, and heart rate. CONCLUSIONS: The echocardiograph results indicated that older people are an at-risk group for developing HAPE. A conservative interpretation of the basic tactical rules for altitudes should be followed for older trekkers or trekkers with known problems of altitude acclimatization ("slow acclimatizer") as SPAP elevates with age. The prophylactic use of Acetazolamide (Diamox®) should be avoided where not necessary for acute medical reasons. Acetazolamide leads to an increase of SPAP, and this may potentially enhance the risk of developing HAPE. Arterial oxygen saturation measurements can provide an indicator for the self-assessment for the risk of developing HAPE and a rule of thumb for the altitude profile, but does not replace a HAPE diagnosis. Backpack weight, sex, workload (actual ascent speed), and pre-existing diseases were not statistically significant factors related to SPAP and TVR (p ≤ 0.05).

Cardiovascular Risk Profiles and Pre-Existing Health Conditions of Trekkers in the Solu-Khumbu Region, Nepal.

BACKGROUND: High-altitude tourist trekking continues to grow in popularity on the Everest Trek in Nepal. We examined which pre-existing cardiovascular and health conditions these global trekkers had and what health issues they encountered during the trek, be it exacerbations of pre-existing conditions, or new acute ones. METHOD: Trekkers (n = 350) were recruited from guesthouses along the Everest Trek, mostly at Tengboche (3860 m). After completing a questionnaire on their health and travel preparation, they underwent a basic physical examination with an interview. RESULTS: Almost half (45%) had pre-existing conditions, mostly orthopaedic and cardiovascular diseases. The average age was 42.7 years (range 18-76). The average BMI was 23.4 kg/m2, but 21% were overweight. A third were smokers (30%), and 86% had at least one major cardiovascular risk factor. A quarter (25%) were suffering from manifest acute mountain sickness (AMS), and 72% had at least one symptom of AMS. Adequate pre-travel examination, consultation, and sufficient personal preparation were rarely found. In some cases, a distinct cardiovascular risk profile was assessed. Hypertensive patients showed moderately elevated blood pressure, and cholesterol levels were favourable in most cases. No cardiovascular emergencies were found, which was fortunate as timely, sufficient care was not available during the trek. CONCLUSION: The results of earlier studies in the Annapurna region should be revalidated. Every trekker to the Himalayas should consult a physician prior to departure, ideally a travel medicine specialist. Preventative measures and education on AMS warrant special attention. Travellers with heart disease or with a pronounced cardiovascular risk profile should be presented to an internal medicine professional. Travel plans must be adjusted individually, especially with respect to adequate acclimatisation time and no physical overloading. With these and other precautions, trekking at high altitudes is generally safe and possible, even with significant pre-existing health conditions. Trekking can lead to invaluable personal experiences. Since organized groups are limited in their flexibility to change their itinerary, individual trekking or guided tours in small groups should be preferred.

Inpatient treatment of trekkers and Nepalese workers in the high-altitude environment of Mt. Everest Region 1996-2011: A retrospective analysis.

BACKGROUND: The study investigates the diagnoses of inpatients (tourists and Nepali workers) of Kunde Hospital (Mt.Everest region) over 15 years. METHODS: Records from January 1996 to September 2011 were analyzed concerning date, gender, age group, nationality, purpose of visit, diagnosis, length of treatment, and condition at discharge. Diagnoses were coded according to ICD-10-WHO 2010. Data were analyzed using descriptive statistics and non-parametric tests. P < 0.05 was defined as significant. RESULTS: 479 inpatients were included: 363 (75.8%) males (202 trekkers (42.2%), 277 Nepalese workers (57.8%)). Most suffered from altitude sickness (45.5%), acute gastroenteritis (10.4%) or acute respiratory infection (8.4%). Severe cases of altitude sickness amongst trekkers decreased but increased amongst workers. Severe cases of acute gastroenteritis amongst trekkers increased. Mean length of inpatient treatment was 4.6 days ±2.7 days. 573/2030 days of treatment were caused by altitude sickness. 70 patients were evacuated, 9 died. CONCLUSION: Altitude illness caused the majority of inpatient treatment and acute gastroenteritis may be an underestimated risk for both groups. Other severe problems were mostly illnesses, not trauma. Improved prevention strategies are needed for both groups. For tourists who often show pre-existing diseases this includes an individual pre-travel expert advice. Nepali workers should be instructed concerning acclimatization.

Time-dependent effects of cadaveric renal transplantation on arterial compliance in patients with end-stage renal disease.

BACKGROUND: Cardiovascular complications are the leading cause of mortality in patients undergoing hemodialysis. Increased arterial stiffness is a strong and independent predictor of cardiovascular risk in these patients. In the present study, we investigated the time-dependent effects of cadaveric renal transplantation on arterial elasticity in end-stage renal disease patients. METHODS: Thirty-six patients underwent successful cadaveric kidney transplantation. Pulse-wave analysis of the radial artery was performed prior to transplantation (day 0) and at six defined intervals after transplantation (day 1 to 90). Compliance of large conduit arteries (C1) and of small resistance arteries (C2) was assessed using a modified Windkessel model of the circulation. RESULTS: Both large artery and small artery compliance were transiently improved within the first four weeks posttransplant reaching a maximum of 122 +/- 42% (C1) and 147 +/- 93% (C2) between day 19 and 23. After the first month, however, elasticity gradually deteriorated to reach baseline values three months after transplantation again. CONCLUSION: The benefits of cadaveric renal transplantation on oscillatory and capacitive artery compliance are only transient. It may be speculated that the subacute and long-term vasoactive effects of calcineurin inhibitors counteract the metabolic benefits of increased renal function on the vasculature.

Cerebral venous sinus thrombosis at high altitude.

Cerebral venous sinus thrombosis (CVST) is a rare but potentially life-threatening medical condition. We describe a case of a 47-year-old woman who presented with headache, speech defects, and visual disturbances, and was later diagnosed with cerebral venous sinus thrombosis. The article describes a possible risk of such thrombotic events with exposure to high altitude environment in patients with coagulation defects such as Factor V Leiden mutation. Besides, such neurological conditions can occur independent of altitude illness and need to be recognized as their management differs.