MILITARY MEDICINE
Year : 2017 | Volume
: 19 | Issue : 2 | Page : 138--141
A Study of High-Altitude-Associated conditions in soldiers less than 50 years of age admitted in the ICU of a tertiary care military hospital operating in a counter insurgency operation area
Umesh Kumar Dash, Abhijit A Karmarkar, Manish Singh Dangi
Department of Anaesthesiology and Critical Care, INHS Asvini, Mumbai, Maharashtra, India
Correspondence Address:
Dr. Abhijit A Karmarkar
Department of Anaesthesiology and Critical Care, INHS Asvini, Colaba, Mumbai - 400 005, Maharashtra
India
Abstract
Background: Altitude related diseases due to low barometric pressure and extreme cold climates are presumed to be the morbidities for soldiers carrying out military operations at altitudes varying from 2500 to 5500 meters above Mean Sea Level (MSL). Aim: The aim of the study was to ascertain high-altitude-related diseases among soldiers <50 years of age admitted in the Intensive Care Unit (ICU) of a tertiary care military hospital. Material and Methods: A study was carried out in a hospital providing tertiary care support to troops for a period of one year. Patients were diagnosed by clinical examination, laboratory rest and radiological imaging. Observations: A total of seventy three patients <50 years who suffer from diseases at high altitude were admitted in the ICU of the hospital during the study period. A total of thirty nine patients were admitted for acute coronary syndrome, twenty two patients were admitted for thrombosis-related disorders including deep venous thrombosis and cerebro-vascular accidents and twelve patients were admitted with acute high altitude related illness. Conclusion: The prevalent diseases among soldiers of less than 50 years of age in the ICU of the hospital may have been caused due to the adverse environmental condition at high altitude.
How to cite this article:
Dash UK, Karmarkar AA, Dangi MS. A Study of High-Altitude-Associated conditions in soldiers less than 50 years of age admitted in the ICU of a tertiary care military hospital operating in a counter insurgency operation area.J Mar Med Soc 2017;19:138-141
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How to cite this URL:
Dash UK, Karmarkar AA, Dangi MS. A Study of High-Altitude-Associated conditions in soldiers less than 50 years of age admitted in the ICU of a tertiary care military hospital operating in a counter insurgency operation area. J Mar Med Soc [serial online] 2017 [cited 2023 Mar 24 ];19:138-141
Available from: https://www.marinemedicalsociety.in/text.asp?2017/19/2/138/225271 |
Full Text
Introduction
It has been recognized that altitudes >1500 m above Mean Sea Level (MSL) affect the health of human beings adversely. The International Society for Mountain Medicine has defined high altitude as 1500–3500 m, very high altitude as 3500–5500 m, and extreme altitude as 5500 m above MSL.[1] Staying at high altitude and exposure to low barometric pressure and partial pressure of oxygen cause hypoxemia.
Acute exposure to such hypoxic atmospheric conditions with inadequate acclimatization predisposes to diseases such as Acute Mountain Sickness (AMS), High-Altitude Pulmonary Edema (HAPE), and High-Altitude Cerebral Edema (HACE).[2],[3],[4]
Acute hypoxia causes an increase in heart rate, myocardial contractility, and cardiac output.[5] There is an increase in the pulmonary artery pressure, hypervolemia, polycythemia, and increased blood viscosity, all lead to additional stress on heart, predisposing personnel to Acute Coronary Syndrome (ACS).[6],[7]
In addition, polycythemia and increase in blood viscosity result in a demonstrable hypercoagulable state causing Deep Venous Thrombosis (DVT) and stroke. Twenty cases of DVT of calf veins were detected among soldiers residing above 5000 m for >10 months.[8] Deep Venous Thrombosis (DVT) DVT of calf veins was similarly demonstrated in Pakistani soldiers staying at high altitude for a prolonged period of time.[9] It has been demonstrated that strokes formed 13.7/1000 of hospital admissions from high altitude area, compared to 1.05/1000 in nonhigh altitude area. Long-term stay (mean altitude stay of 10.2 months) at high altitude is associated with higher risk of stroke.[10]
The aim of the study was to carry out a descriptive study for a duration of 1 year to ascertain high-altitude-related diseases among soldiers <50 years of age admitted in the ICU of a tertiary care military hospital, operating in CI Op areas.
Materials and Methods
The study was carried out for a duration of 1 year in a 12-bedded ICU of a tertiary care hospital providing comprehensive critical care to all critically ill patients including trauma related to military operations.
All patients in the study were evacuated from heights ranging from 2000 to 5500 m above MSL. None of the patients were natives of high-altitude areas.
They underwent clinical examination, laboratory, and radiological tests. Baseline laboratory investigations in the form of complete blood count, prothrombin time, partial thromboplastin time, platelet count, electrocardiogram, and X-ray chest were done. Further laboratory investigations, Magnetic Resonance Imaging (MRI), or Computed Tomography (CT) scan for Transient Ischemic Attack (TIA)/cerebrovascular events and Color Doppler for Deep Venous Thrombosis (DVT) were carried out if necessary
ACS was diagnosed by the presence of one of the following three criteria:[11]
Typical symptoms of acute myocardial infarction (AMI) with ST elevation on electrocardiography (ECG) and raised creatine kinase [CK]-MB isoenzyme or troponinTypical symptoms of AMI without ST elevation but raised CK-MB isoenzyme or troponinSymptoms of unstable angina or ECG indicative of ischemia, with normal enzymes.
Patients were diagnosed as a case of cerebrovascular accident (CVA) or stroke as per guidelines prescribed by modified National Institutes Of Health Stroke Scale.[12]
Based on these findings, the patients were divided into three groups:
Group I - ACSGroup II - Thrombosis-related disorder including deep venous thrombosis (DVT) and CVAGroup III - AMS, High- HAPE, and HACE.
Those patients who had other risk factors for ACS, CVA, and DVT such as tobacco and alcohol consumption, hypertension, family history, and diabetes mellitus were excluded from the study.
Results
After exclusion of patients based on the risk factors, a total of 73 patients <50 years of age were identified with diseases which were likely due to exposure to high altitude [Table 1].{Table 1}
It was observed that ACS and thrombosis-related diseases were more frequent among the 31–40 years age groups, while acute high-altitude-related diseases were more frequent among the younger age group (21–30 years). It was also observed that there were no acute high-altitude-related diseases among the older age group (41–50 years) [Table 2].{Table 2}
39 patients were admitted for ACS. Among them, 12 were in the age group of 41–50 years, 20 in the age group of 31–40 years, and 7 in the age group of 21–30 years. These patients include both ST-elevated and non-ST elevated Myocardial Infarction (MI), unstable angina as per the diagnostic criteria and one case of Prinzmetal angina diagnosed with rest angina, Troponin was positive in all the 31 patients of ST-elevated and non-ST-elevated MI, but was negative in the 7 patients of unstable angina and the patient with Prinzmetal Angina. One patient developed PSVT and another developed VT; both the patients were successfully cardioverted to normal rhythm. Three patients developed cardiac dysfunction which was diagnosed by clinical findings and echocardiography, and one of them died of MI.
22 patients were admitted for thrombosis-related disorders including DVT and CVAs. Among them, 6 were in the age group of 41–50 years, 12 in the age group of 31–40 years, and 4 in the age group of 21–30 years. Four patients had deep venous thrombosis in lower limb (two of them are in both lower limbs), one had DVT in right upper limb, and three had mesenteric vein thrombosis with small intestine ischemia. There were also three patients of TIA where one had loss of consciousness, one had bitemporal hemianopia with diminished vision, whereas another presented with diminish vision only. Arterial ischemic strokes and cerebral venous thrombosis was seen in three more patients. One patient who had a definite history of short-term very high-altitude exposure to 4000 m above MSL, during Amarnath yatra, was admitted as a case of left hemiplegia. Among the thrombosis-related disease, there was only one fatality. The patient was received with Glasgow Coma Score of 5/15 and was intubated and ventilated but had a progressively deteriorating course. CT scan of the victim showed left thalamic bleed with intraventricular extension and large midline shift.
A total of 12 patients were admitted with acute high-altitude-related illness. Out of them, three were in the age group of 31–40 years and nine in the age group of 21–30 years. Six had AMS, two had HAPE, and HACE and two patients had both HAPE and HACE. All patients had acute exposure to high altitude. Exposure duration and appearance of signs and symptoms varied from 6 h to 36 h. Among some patients, there were difficulties in ascertaining precise time of development of symptoms and signs after exposure to high altitude due to altered level of consciousness. Positive signs and symptoms of these patients are listed in [Table 3]. MRI of brain in three of the four patients of HACO showed the presence of vasogenic edema. Chest X-ray of all four patients of HAPO revealed the presence of patchy infiltrates in the right middle and lower lobes in one patient and bilateral infiltration in three patients. ECG finding revealed right ventricular strain pattern with right axis deviation in one of the two patients with both HACO and HAPO.{Table 3}
Laboratory and biochemical investigation findings are listed in [Table 4]. The analysis of variance was used to compare the laboratory and biochemical parameters among different disease groups.{Table 4}
Discussion
Soldiers deployed for counter-insurgency operations are required to live at moderate to very high altitudes. Most of them are from the plains and are required to stay in high altitude for varying periods of time. They are exposed to severe environmental stresses such as cold temperature (ranging from 15 to 5°C in summer to −5 to −25°C in winter in different heights), low humidity (relative humidity 10%–50%), increased ultraviolet radiation, and decreased atmospheric pressure (which varies from 0.74 atm to 0.5 atm).
Deployed personnel in our study were mostly young individuals (age <50 years). High-altitude-related illness among young troops constituted 19% of total medical wing ICU admission and 11% of total ICU admission. Furthermore, only a small number of patients (5 ACS and 4 thrombosis-related disorder) were above 50 years of age.
In the general population, ACS in young adults constituted up to 25% of total ACS cases and are associated with risk factors such as tobacco consumption, hypertension, diabetes mellitus, obesity, and dyslipidemia.[13] Similarly, stroke in young adults constituted 4.3%–25% of total stroke cases and associated with acquired or congenital diseases such as rheumatic heart disease, atrial fibrillation, vasculitis, arteriovenous malformations, bleeding disorders, anticoagulants, and many other disease states.[14] On the other hand, Armed Forces personnel posted to high-altitude areas are relatively healthy young individuals and do not have most of the above-associated risk factors or diseases. However, deployment in counterinsurgency and low-intensity conflict (LIC) areas, high altitude, extreme temperatures in glaciers, and deserts are all potential stressors for soldiers on land and may contribute to the disease burden.[15]
In a previous study, it has been shown that severity of AMS was inversely related to age [16] and older person has a better tolerance to high altitude [17] which was also seen in our study. Although there was strict implementation of acclimatization process for all the troops before induction, a few susceptible individuals, both newly inducted and some coming after leave also developed acute high-altitude-related illness.[17],[18]
Troops in their late 40s are more likely to be in administrative rather than operational jobs. In a multidimensional study among respondents from LIC area there was a significantly higher scores of stress-related parameters, in comparison to those located in other areas. It was also found that significantly higher number of respondents from highly active LIC and >1 year in area scored above cutoff levels in some stress-related parameters.[19]
Hemoglobin level were significantly higher (P < 0.05) among the ACS and thrombosis-related diseases in comparison to acute high-altitude-related diseases. However, the hemoglobin was more among all the three disease groups in comparison to the lowlanders.[20]
Conclusion
This descriptive study was carried out at a tertiary care hospital that receives referred patients from high altitude areas. The study demonstrated a higher than usual prevalence of morbidity in the age group <50 years who were referred for tertiary care treatment from high altitude locations. This possibly is due to the various deleterious effects of high altitude environment in addition to the peculiar stressors of low intensity conflict. The limitation of the study was that a sample size could not be calculated in such a security scenario and all patients admitted to the ICU of the tertiary care centre were taken into consideration and thus generalisability to the entire service personnel and situation will not be appropriate. A well designed larger study carried out in such a scenario will validate results from our study.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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