Cases Of High Altitude Pulmonary Edema Research Articles

Recurrence Rate of High-altitude Pulmonary Edema in Lowlanders Inducted Temporarily to High-altitude Areas

Abstract Background: Some section of the Indian population resides in high-altitude areas of the mighty Himalayas. In addition to the residents who inhabit mountainous areas, there is also a group of lowlanders who occasionally visit these regions temporarily for work-related purposes or vacations. These individuals are prone to high-altitude illnesses, including acute mountain sickness and high-altitude pulmonary edema (HAPE). This cohort study was undertaken, among acclimatized and nonacclimatized lowlanders based on 3 years of data at a tertiary care hospital, to study the recurrence rate of HAPE in lowlanders. Materials and Methods: The inception cohort consisted of consecutive cases of HAPE among lowlanders, temporarily posted to these high-altitude regions, over 3 years. This cohort was followed up for at least 1 year. The recurrence rate of HAPE in terms of incidence density in person-months and cumulative incidence was calculated, and variables, including clinical features, altitudes at which the symptoms occurred, mode of induction to the high-altitude area, and time of onset of HAPE episodes postinduction altitudes, were studied. Results: The study revealed the recurrence of HAPE as an incidence density of 88.7 per 1000 person-months (95% confidence limit 66.1–115.9 per 1000 person-months). The cumulative incidence was 125 per 1000, over an average follow-up of 22.54 months (95% confidence limit 26–323 per 1000). The study revealed that the recurrence was found to occur at similar altitudes as the previous episode even after following strict acclimatization protocols and slow induction to the high-altitude area by road route with the onset of symptoms within 72 h of entry into the high-altitude area. Conclusion: This study brought out that there is a risk of recurrence of HAPE in lowlanders temporarily inducted to high-altitude areas, with previous episodes of HAPE at similar altitudes as previous episodes, even when acclimatization protocols are followed.

Rescue Emergencies Due to High-Altitude Illnesses Are Rare in Switzerland.

Background: Despite a potential high risk of acute mountain sickness (AMS) in the Swiss Alps, there is a lack of analyses concerning its relevance over longer periods. In consequence, the aim of this study is to analyze the prevalence of AMS in comparison to other causes of mountain emergencies in recent years in Switzerland. Material and Methods: Based on the central registry of mountain emergencies of the Swiss Alpine Club (SAC), all cases in the period between 2009 and 2020 were analyzed for AMS including the most severe forms of high-altitude pulmonary edema (HAPE) and high-altitude cerebral edema (HACE). Emergencies were assessed for the severity of the event with a National Advisory Committee for Aeronautics (NACA) score. Results: From a total of 4596 high-altitude mountaineering emergencies identified in the observational period, a total number of 352 cases of illnesses were detected. Detailed analysis revealed 85 cases of AMS, 5 cases of HAPE, and 1 case of HACE. The average altitude was 3845 ± 540 m. Most cases were in the canton of Valais, especially in the Monte Rosa region and the mountains of the Mischabel group (Täschhorn, Dom, Südlenz, Nadelhorn, Hohberghorn). There were only three deaths related to high-altitude illnesses; all the other events could be identified as moderate to severe but not life-threatening. Discussion: An emergency due to AMS that requires rescue is unlikely in the Swiss Alps. This does not imply that AMS is not a concern. However, the facts that the maximal altitude is relatively low and that fast self-descents often seem possible probably minimize the likelihood that mountaineers with symptoms contact emergency services.

Differential diagnosis of high altitude pulmonary edema and COVID-19 with computed tomography feature

To investigate the computed tomography (CT) characteristics and differential diagnosis of high altitude pulmonary edema (HAPE) and COVID-19, CT findings of 52 cases of HAPE confirmed in Medical Station of Sanshili Barracks, PLA 950 Hospital from May 1, 2020 to May 30, 2020 were collected retrospectively. The size, number, location, distribution, density and morphology of the pulmonary lesions of these CT data were analyzed and compared with some already existed COVID-19 CT images which come from two files, "Radiological diagnosis of COVID-19: expert recommendation from the Chinese Society of Radiology (First edition)" and "A rapid advice guideline for the diagnosis and treatment of 2019 novel corona-virus (2019-nCoV) infected pneumonia (standard version)". The simple or multiple ground-glass opacity (GGO) lesions are located both in the HAPE and COVID-19 at the early stage, but only the thickening of interlobular septa, called "crazy paving pattern" belongs to COVID-19. At the next period, some increased cloudy shadows are located in HAPE, while lesions of COVID-19 are more likely to develop parallel to the direction of the pleura, and some of the lesions show the bronchial inflation. At the most serious stage, both the shadows in HAPE and COVID-19 become white, but the lesions of HAPE in the right lung are more serious than that of left lung. In summary, some cloudy shadows are the feature of HAPE CT image, and "crazy paving pattern" and "pleural parallel sign" belong to the COVID-19 CT, which can be used for differential diagnosis.

Clinico-epidemiological profile of high altitude pulmonary edema

Background: With increase in the footfall to mountainous areas for occupational and recreational purposes, tackling the burden of high-altitude illnesses is a growing public health challenge. High-altitude pulmonary edema (HAPE) is a serious medical condition with peculiar epidemiological characteristics. HAPE is a significant cause of morbidity and mortality among Indian soldiers posted to high-altitude areas. Aims and objectives of the study were to study the common clinical presentation of HAPE among Indian army soldiers and to study the association between induction patterns and acclimatization status with the onset of HAPE.Methods: An observational study was undertaken to study the clinical and epidemiological characteristics of all cases of HAPE from years 2016 to 2019, among Indian army soldiers posted to high-altitude areas in Ladakh. Diagnosis was made by the Lake-Louise consensus criteria. Data was entered in Microsoft Excel and descriptive and inferential statistical tools were applied to test for associations between the variables studied.Results: The overall incidence rate of HAPE was found to be 5.91 per 1,000 soldiers with high frequency among young men. Breathlessness, cough, and headache were the common complaints. 69.45% of cases occurred among men who revisited the mountains after a brief sojourn to the plains. At higher altitudes, incidence rates were higher among acclimatized individuals.Conclusions: HAPE occurs more frequently during the subsequent visits compared to first exposure to high altitude. At extreme altitudes, acclimatization protocols do not confer complete protection against HAPE.

EPAS1 and VEGFA gene variants are related to the symptoms of acute mountain sickness in Chinese Han population: a cross-sectional study

BackgroundMore people ascend to high altitude (HA) for various activities, and some individuals are susceptible to HA illness after rapidly ascending from plains. Acute mountain sickness (AMS) is a general complaint that affects activities of daily living at HA. Although genomic association analyses suggest that single nucleotide polymorphisms (SNPs) are involved in the genesis of AMS, no major gene variants associated with AMS-related symptoms have been identified.MethodsIn this cross-sectional study, 604 young, healthy Chinese Han men were recruited in June and July of 2012 in Chengdu, and rapidly taken to above 3700 m by plane. Basic demographic parameters were collected at sea level, and heart rate, pulse oxygen saturation (SpO2), systolic and diastolic blood pressure and AMS-related symptoms were determined within 18–24 h after arriving in Lhasa. AMS patients were identified according to the latest Lake Louise scoring system (LLSS). Potential associations between variant genotypes and AMS/AMS-related symptoms were identified by logistic regression after adjusting for potential confounders (age, body mass index and smoking status).ResultsIn total, 320 subjects (53.0%) were diagnosed with AMS, with no cases of high-altitude pulmonary edema or high-altitude cerebral edema. SpO2 was significantly lower in the AMS group than that in the non-AMS group (P = 0.003). Four SNPs in hypoxia-inducible factor-related genes were found to be associated with AMS before multiple hypothesis testing correction. The rs6756667 (EPAS1) was associated with mild gastrointestinal symptoms (P = 0.013), while rs3025039 (VEGFA) was related to mild headache (P = 0.0007). The combination of rs6756667 GG and rs3025039 CT/TT further increased the risk of developing AMS (OR = 2.70, P < 0.001).ConclusionsUnder the latest LLSS, we find that EPAS1 and VEGFA gene variants are related to AMS susceptibility through different AMS-related symptoms in the Chinese Han population; this tool might be useful for screening susceptible populations and predicting clinical symptoms leading to AMS before an individual reaches HA.Trial registrationChinese Clinical Trial Registration, ChiCTR-RCS-12002232. Registered 31 May 2012.

Is it time to revise the acclimatization schedule at high altitude? Evidence from a field trial in Western Himalayas

BackgroundIn Western Himalayas, Indian Army soldiers take 11 days (6 days of acclimatization and 5 days of travel) on a sea-level to high altitude road (SH road) to reach a high altitude location (HAL) situated at an altitude of 11,500 feet from sea-level location (SLL) at an altitude of 1150 feet while following acclimatization schedule (AS). AS has an extra safety margin over the conventional ‘mountaineering thumb rule’ of not exceeding 500m sleeping altitude above 3000m altitude. We carried out this randomised field trial to study the feasibility of moving large number of troops rapidly from SLL to HAL on SH road in western Himalayas in 4 days under pharmaco-prophylaxis. MethodsBased on the pharmaco-prophylaxis, at SLL 508 healthy lowland soldiers were divided into two groups: ‘A’ (n=256) with Acetazolamide+Dexamethasone and ‘B’ (n=252) with Acetazolamide+Placebo. They travelled rapidly by road to HAL in 4 days and prevalence of acute mountain sickness (AMS), high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE) during the ascent was measured. ResultsPrevalence of AMS was found to be 1.56% and 1.59% in group ‘A’ and group ‘B’ respectively during the ascent with no cases of HAPE and HACE. ConclusionAt least on SH road, troops can be inducted rapidly to HAL from SLL in 4 days under pharmaco-prophylaxis with Acetazolamide with minimal occurrence of acute high altitude illnesses.

Biomarkers of hypoxia, endothelial and circulatory dysfunction among climbers in Nepal with AMS and HAPE: a prospective case-control study.

The mechanisms underlying acute mountain sickness (AMS) and high-altitude pulmonary edema (HAPE) are not fully understood. We hypothesized that regulators of endothelial function, circulatory homeostasis, hypoxia and cell stress contribute to the pathobiology of AMS and HAPE. We conducted a prospective case-control study of climbers developing altitude illness who were evacuated to the CIWEC clinic in Kathmandu, compared to healthy acclimatized climbers. ELISA was used to measure plasma biomarkers of the above pathways. Of the 175 participants, there were 71 cases of HAPE, 54 cases of AMS and 50 acclimatized controls (ACs). Markers of endothelial function were associated with HAPE: circulating levels of endothelin-1 (ET-1) were significantly elevated and levels of sKDR (soluble kinase domain receptor) were significantly decreased in cases of HAPE compared to AC or AMS. ET-1 levels were associated with disease severity as indicated by oxygen saturation. Angiopoietin-like 4 (Angptl4) and resistin, a marker of cell stress, were associated with AMS and HAPE irrespective of severity. Corin and angiotensin converting enzyme, regulators of volume homeostasis, were significantly decreased in HAPE compared to AC. Our findings indicate that regulators of endothelial function, vascular tone and cell stress are altered in altitude illness and may mechanistically contribute to the pathobiology of HAPE.

High altitude pulmonary edema (HAPE) with pulmonary embolism

High altitude pulmonary edema (HAPE) is a life-threatening condition occurring at heights above 2500 meter mostly within 2-4 days of entry in high altitude. Postmortem studies showed evidence of thrombi in cases of HAPE suggesting possible role of thrombosis in the pathogenesis of HAPE. Here, we are presenting the two cases of HAPE with pulmonary embolism, and the possibility of pulmonary embolism should be considered in cases of HAPE with persistent radiographic opacities despite oxygen or descent.

Objective criteria for diagnosing high altitude pulmonary edema in acclimatized patients at altitudes between 2700 m and 3500 m

BackgroundThe criteria used for diagnosing high altitude illnesses are largely based on Western literature. This study was undertaken to define objective, simple and reliable diagnostic criteria for high altitude pulmonary edema (HAPE) in Indian soldiers at altitudes between 2700m and 3500m. MethodsClinical data of 235 cases of HAPE that occurred between 2700m and 3500m were analysed. Receiver operator characteristic (ROC) curve analysis was used to select simple clinical parameters suitable for the diagnosis of HAPE at peripheral medical facilities. Cut-off values and their reliability for the diagnosis of HAPE were defined. ResultsHAPE occurred 2.8±2.2 days after arrival at altitudes between 2700m and 3500m. Breathlessness, cough, chest discomfort and headache were the commonest symptoms. Low pulse oximetry (SPO2) values than normal for this altitude were seen in 89% of patients. ROC analysis of clinical parameters identified a heart rate more than 95 beats per minute (bpm), respiratory rate more than 21 per minute and SPO2 less than 86% while breathing ambient air at this altitude as diagnostic of HAPE. The sensitivity and specificity of these cut-offs was 0.66, 0.83 and 0.82 and 0.94, 0.95 and 0.93 respectively. ConclusionA heart rate of more than 95bpm, respiratory rate more than 21 per minute and SPO2 less than 86% breathing room air in individuals complaining of breathlessness, cough, chest discomfort or headache within the first 5 days of arrival at altitudes between 2700m and 3500m is highly suggestive of HAPE.

Incidence of High Altitude Illness at Mt. Kailash Mansarovar (4500m), Tibet by Direct Helicopter Flight, A Cross-sectional Study

Introduction Most of the pilgrims with their religious purpose would like to visit at Mt. Kailash Mansarovar 4500m or Gosainkund Lake (4300m). The high altitude illness is used to describe the cerebral and pulmonary syndromes that can develop in unacclimatized persons shortly after ascent to high altitude. High altitude illness usually occurs at altitude above 2500m. Sometime it may occur at the altitude of 1500m. This is mainly caused by hypoxia but is compounded by cold and with rapid ascent. Objectives To determine the incidence of HAI (High Altitude Illness) which include AMS (Acute Mountain Sickness), high altitude cerebral edema (HACE), high altitude pulmonary edema (HAPE) in pilgrims who fly directly then drive with a single overnight at Taklacoat and then Mt. Kailash Mansarovar lake in Tibet (4500m) during the 2 nd day and returning back to Kathmandu on the 3rd day. Methods Study of 37 pilgrims at Mt. Mansarovar with a close look at their clinical history, signs and symptoms and evaluated by the Lake Louise Consensus for AMS, HACE, HAPE. Results Out of 37 pilgrims, who flew directly from Kathmandu at 1300m to Simikot, Hilsa, Taklacoat and Mansarovar. 35.13 percent (13) of them developed high altitude illness. Among total 13 illnesses, 9(24.32%) were affected with AMS and 4(10.81%) with dangerous early HAPE. There was no gender difference for AMS and HAPE. Younger ages were more susceptible for AMS as well as those who took a holy dip in the lake. Such persons developed more chances of having HAPE. Using Lake Louise criteria showed that the incidence of AMS was higher and that of HAPE was lower among high altitude illness. Those who flew directly with a drive on the 2 nd day to Mansarovar Lake were found to have a higher incidence of AMS, but fewer cases of HAPE. These results were found in spite of taking prophylactic Acetazolamide and Dexamethasone. Younger and elderly age groups were found to be more susceptible. Conclusion There should be at least a 1-2 over night stay at an intermediate altitude, to help the body acclimatize and reduce unwanted medical problems. This way more and more elderly and younger pilgrim can visit such holy places.

Acetazolamide Fails to Decrease Pulmonary Artery Pressure at High Altitude in Partially Acclimatized Humans

In this randomized, double-blind placebo controlled trial our objectives were to determine if acetazolamide is capable of preventing high altitude pulmonary edema (HAPE) in trekkers traveling between 4250 m (Pheriche)\4350 m (Dingboche) and 5000 m (Lobuje) in Nepal; to determine if acetazolamide decreases pulmonary artery systolic pressures (PASP) at high altitude; and to determine if there is an association with PASP and signs and symptoms of HAPE. Participants received either acetazolamide 250 mg PO BID or placebo at Pheriche\Dingboche and were reassessed in Lobuje. The Lake Louise Consensus Criteria were used for the diagnosis of HAPE, and cardiac ultrasonography was used to measure the velocity of tricuspid regurgitation and estimate PASP. Complete measurements were performed on 339 of the 364 subjects (164 in the placebo group, 175 in the acetazolamide group). No cases of HAPE were observed in either study group nor were differences in the signs and symptoms of HAPE found between the two groups. Mean PASP values did not differ significantly between the acetazolamide and placebo groups (31.3 and 32.6 mmHg, respectively). An increasing number of signs and symptoms of HAPE was associated with elevated PASP (p < 0.01). The efficacy of acetazolamide against acute mountain sickness, however, was significant with a 21.9% incidence in the placebo group compared to 10.2 % in the acetazolamide group (p < 0.01). Given the lack of cases of HAPE in either group, we can draw no conclusions about the efficacy of acetazolamide in preventing HAPE, but the absence of effect on PASP suggests that any effect may be minor possibly owing to partial acclimatization during the trek up to 4200 m.

Effect of Altitude on the Heart and the Lungs

This review focuses on the effects of altitude exposure from 1 to several days or weeks as occurs in tourists, trekkers, and mountaineers who visit high altitude and normally reside near sea level. We briefly review the acute physiological adjustments and early acclimatization that occur in the cardiovascular system and the lungs of healthy individuals. These ensure life-sustaining oxygen delivery to the tissues despite a reduction in the partial pressure of inspired oxygen between 20% and 60% at 2500 and 8000 m, respectively. One of the acute adjustments, hypoxic pulmonary vasoconstriction (HPV), may be disadvantageous in those with a vigorous response and lead to 2 potentially lethal illnesses, high-altitude pulmonary edema (HAPE) and subacute mountain sickness (SAMS), which we present in more detail. Finally, on the basis of knowledge about the acute physiological adjustments and acclimatization and, when available, a review of the literature, we discuss the high-altitude tolerance of patients with coronary artery disease, congestive heart failure, arrhythmias, systemic hypertension, and pulmonary hypertension. ### Circulation The major effects of acute hypoxia on the heart and lung are shown in Figure 1. Hypoxia directly affects the vascular tone of the pulmonary and systemic resistance vessels and increases ventilation and sympathetic activity via stimulation of the peripheral chemoreceptors.1 Interactions occur between the direct effects of hypoxia on blood vessels and the chemoreceptor-mediated responses in the systemic and pulmonary circulation. Figure 1. Effects of hypoxia on systemic and pulmonary circulation. Unraveling the underlying mechanisms of the hypoxic vasodilatation of systemic arterioles is an active area of research. Several mechanisms appear to regulate local oxygen delivery according to the needs of the tissues2,3; for instance, the release of ATP from red blood cells and the generation of NO by various ways appear to regulate local oxygen delivery according to the needs …

High altitude headache: efficacy of acetaminophen vs. ibuprofen in a randomized, controlled trial

Ibuprofen has been shown to be more effective than placebo in the treatment of high altitude headache (HAH), but nonsteroidal anti-inflammatory agents have been linked to increased incidence of gastrointestinal (GI) side effects and high-altitude pulmonary edema (HAPE). We postulated that acetaminophen, which does not share ibuprofen’s theorized causal link to GI side effects or HAPE, could provide effective HAH therapy. We conducted a prospective, randomized, double-blind, clinical trial of ibuprofen vs. acetaminophen in the Solu Khumbu, Nepal: Mt. Everest Base Camp, Pheriche, Dingboche (4240 m to 5315 m). Seventy-four consecutive patients (ages 13 to 61 years) were randomized, were assessed with the Lake Louise Acute Mountain Sickness (AMS) criteria, and received a physical examination (which included vital signs, oxygen saturation as measured by pulse oximetry (SpO 2), and assessment of clinical Lake Louise AMS criteria). Patients then received either 400 mg of ibuprofen (IBU) or 1000 mg of acetaminophen (ACET), and were asked to rate their cephalgia using a 10-cm visual analog scale (VAS). Thirty-nine patients received IBU, and 35 received ACET. Baseline Lake Louise AMS scores were identical in the two groups (mean = 5.9). No differences in mean VAS scores between IBU and ACET groups were noted at time 0 (presentation), 30, 60, or 120 min. No cases of HAPE or high altitude cerebral edema were noted during the study period. In this study population, acetaminophen was as effective as ibuprofen in relieving the pain of HAH.

Differentiation of pulmonary embolism from high altitude pulmonary edema.

To differentiate the high altitude pulmonary edema (HAPE) from pulmonary embolism (PE) by clinical probability model of PE, lactate dehydrogenase (LDH), aspartate transaminase (AST) and D-dimer assays at high altitude. A prospective study. The study was carried out at CMH, Skardu, from October 2001 to December 2002. Consecutive 40 patients evacuated from height > 3000 meters with symptoms of PE or HAPE were included. Clinical pretest probabilities scores of PE, Minutex D-dimer assay (Biopool international) and cardiac enzymes estimation by IFCC approved methods, were used for diagnosis. Mann-Whitney U test was applied by using SPSS and level of significance was taken at (p<0.05). Out of 40 subjects, 31 HAPE and 9 patients of PE were initially diagnosed on the basis of clinical features, D-dimer assay and V-Q scanning. Out of 9 patients of PE; 3 had plasma D-dimer between 250-500 ng/ml and 6 > 500 ng/ml. Plasma D-dimer of 500 ng/ml was considered as cut-off value; 6 (66.7%) patients of PE could be diagnosed and 30 (96.7%) cases of HAPE excluded indicating very good negative predictive value. Serum LDH, AST and CK were raised above the reference ranges in 8 (89%), 7 (78 %) and 3 (33 %) patients of PE as compared to 11 (35%), 6 (19%) and 9 (29 %) of HAPE respectively. Clinical assessment in combination with D-dimer assay, LDH and AST can be used for timely differentiation of PE from HAPE at high altitude where diagnostic imaging procedures are not available.

Ambulatory Physiological Status Monitoring during a Mountaineering Expedition

To evaluate an ambulatory physiological monitoring system during a mountaineering expedition. We hypothesized that the Environmental Symptoms Questionnaire, combined with frequent measurement of oxygen saturation and core temperature, would accurately identify cases of environmental illness. Twelve military mountaineers took a daily Environmental Symptoms Questionnaire, monitored fingertip oxygen saturations, and recorded core temperatures while climbing a 4,949-m peak. Illnesses identified by the system were compared with those identified by spontaneous reports. The system correctly identified one case of high-altitude pulmonary edema and two illnesses that were not reported to the physician (one case of acute mountain sickness and one of self-limited symptomatic desaturation). However, it did not identify two illnesses that were severe enough to preclude further climbing (one case of sinus headache and one of generalized fatigue). Our monitoring system may complement, but cannot replace, on-site medical personnel during mountaineering expeditions.

Herb Hultgren in Peru: what causes high altitude pulmonary edema?

Herbert Hultgren, a cardiologist who kept a careful diary all his career, arrived in Peru at the beginning of 1959 to study the occurrence of pulmonary hypertension in children at high altitude with patent ductus arteriosus. There, he was told about a strange condition, high altitude pulmonary edema (HAPE), and found that to Peruvian physicians looking after mine employees and their families, its occurrence was almost routine. With his Peruvian colleagues, Herb immediately began a systematic study of the condition, including catheter studies. Though the absence of left ventricular enlargement suggested a non-cardiac form of pulmonary edema, and though this is what he suggested in his first publication, in two subsequent papers, one written with Charles Houston, who contributed cases occurring in mountaineers, Herb wrote that the most probable cause was left ventricular failure. What is extraordinary is that before he finally submitted the two papers, he had certain knowledge that in one case of HAPE at least, left atrial pressure had been shown to be normal. Herb's contributions, then and later, to the elucidation of HAPE were enormous.

Viral respiratory infection increases susceptibility of young rats to hypoxia-induced pulmonary edema.

Recent clinical observations of a high incidence of preexisting respiratory infections in pediatric cases of high-altitude pulmonary edema prompted us to ask whether such infections would increase the susceptibility to hypoxia-induced pulmonary edema in young rats. We infected weanling rats with Sendai virus, thus causing a mild respiratory infection. Within 7 days of infection, Sendai virus was essentially undetectable by using viral culture and immunohistochemical techniques. Animals at day 7 of Sendai virus infection were then exposed to normobaric hypoxia (fraction of inspired O2 = 0.1) for 24 h and examined for increases in gravimetric lung water and in vascular permeability, as well as for histological evidence of increased lung water. Bronchoalveolar lavage was performed on a separate series of animals. Compared with control groups, infected hypoxic animals showed significant increases in perivascular cuffing, gravimetric lung water, and lung protein leak. In addition, infected hypoxic animals had increases in lavage fluid cell counts and protein content compared with controls. We conclude that young rats, exposed to moderate hypoxia while recovering from a mild viral respiratory infection, may demonstrate evidence of early pulmonary edema formation, a finding of potential relevance to human high-altitude pulmonary edema.

Altitude-related illness in two California national parks.

High-altitude illness encompasses a spectrum of disorders related to the hypoxia experienced by individuals at elevation. Altitude-related illness has been well described in the United States, but there are no studies published in the medical literature looking at the occurrence of high-altitude illness within the US National Parks system. The purpose of this study is to describe the incidence, treatment, and outcomes of visitors to Sequoia and Kings Canyon National Parks who presented to emergency medical services (EMS) personnel with signs and symptoms consistent with high-altitude illness. We conducted a retrospective review of all EMS patient care records (PCRs) from Sequoia and Kings Canyon National Parks during the study period of June 1992 to August 1995. There were 23 cases of altitude-related illness identified by EMS personnel in the parks during the 38-month study period, including five cases of high-altitude pulmonary edema and 19 cases of acute mountain sickness. One patient died, nine patients were transported to local hospitals, nine patients were assisted in their descent and then released from medical care, and four patients were treated and then allowed to continue their travels. There was an average of 5.9 cases per year of high-altitude illness and an incidence of one case per 27 EMS contacts. We conclude that altitude-related illness does occur in Sequoia and Kings Canyon National Parks and, although high-altitude illness accounts for only 4% of EMS contacts, caring for these patients uses a significant amount of national park resources. We suggest continued training of emergency medical technicians and park medics in the recognition and treatment of these disorders. We also support education of hikers to reduce or prevent the morbidity associated with altitude-related illness.

Lung pathology in high-altitude pulmonary edema

Autopsy findings in 10 cases of high-altitude pulmonary edema have been collected from published articles and personal observations. All cases were males with a mean age of 37 years (22-62). The altitude of occurrence was from 8400 to 17 500 feet. The mean combined lung weight in nine cases was 1682 g (1200-3000 g). Cerebral edema was present in five of eight cases. The most frequency pulmonary findings in addition to diffuse edema consisted of leukocyte infiltrates, alveolar hemorrhages, thrombi in small pulmonary arteries, and alveolar hyaline membranes. Pulmonary infarction was present in only one case. Right ventricular dilatation was commonly present. The left ventricle was normal. No significant coronary disease was present.

High-altitude Pulmonary Edema with Pulmonary Thromboembolism

High-altitude pulmonary edema (HAPE) is a form of noncardiogenic pulmonary edema. The pathophysiology of HAPE remains unclear. A case of HAPE was associated with pulmonary thromboembolism of a left upper pulmonary artery. Pulmonary thromboembolism was an important factor in development of HAPE in this case.