High Altitude Pulmonary Edema (HAPE)MANAGEMENT

ENVIRONMENTAL AND EXPOSURE PRESENTATIONS · 12 SECTIONS

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711 items

☷ Legend

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Cardiovascular Presentations71▾

Respiratory Presentations52▾

Neurological Presentations83▾

Gastrointestinal Presentations74▾

Genitourinary and Reproductive Presentations48▾

Infectious Disease Presentations148▾

Trauma Presentations89▾

Toxicologic Presentations80▾

Psychiatric Presentations26▾

Musculoskeletal and Rheumatologic Presentations96▾

Dermatology Presentations23▾

Environmental and Exposure Presentations27▾

Acute Mountain Sickness Arterial Gas Embolism Bee-Wasp Sting (Anaphylaxis)Chilblains Ciguatera Fish Poisoning Coral Cut Decompression Sickness Electrical Burn Injury Envenomation (snake, spider, insect)High Altitude Cerebral Edema (HACE)High Altitude Pulmonary Edema (HAPE)High-altitude illness Hypothermia Hypothermia (Mild)Hypothermia (Severe)Immersion Foot Lightning Strike Injury Scombroid Fish Poisoning Scorpion Envenomation Sea Urchin Injury Shark Bite Snake Envenomation Spider Bite (Black Widow)Spider Bite (Brown Recluse)Stingray Spine Injury Tick paralysis White Phosphorus Burn

Hematologic and Oncologic Presentations36▾

Pediatric-Specific Presentations19▾

Endocrine and Metabolic Presentations45▾

ENT and Maxillofacial Presentations27▾

Ophthalmologic Presentations19▾

Obstetric Presentations23▾

Systemic and Miscellaneous Presentations17▾

01Approach to the Critical Patient/attcp60

Immediate priorities

›Airway and breathing threats

›Severe hypoxemia requiring immediate oxygen

›SpO2 50-70% at altitude is a life-threatening emergency

›Supplemental O2 at 2-4 L/min as first action

›If O2 unavailable, immediate descent is mandatory

›Respiratory failure patterns

›Dyspnea at rest with pink frothy sputum

›Cyanosis with inability to speak full sentences

›Accessory muscle use and respiratory fatigue

›If SpO2 fails to reach >90% within 5 minutes of high-flow O2, escalate to hospital level care

›Indicates severe HAPE

›Intubation may be required in refractory cases

›Circulation and hemodynamics

›Tachycardia from hypoxemia and pulmonary hypertension

›Heart rate typically 100-130 bpm

›Worsens with exertion

›Hypotension in severe or decompensated cases

›SBP < 90 mmHg triggers resuscitation priorities

›MAP < 65 mmHg

›Minimize all patient exertion — exertion raises pulmonary artery pressure acutely

›Strict rest at all times

›Carry patient rather than assist ambulation

›Key early decision points

›Field vs hospital setting

›Field: descent + O2 (if available) + nifedipine

›Hospital: O2, bed rest, +/- nifedipine, +/- CPAP

›Concurrent HACE assessment

02History/hx64

Altitude exposure and ascent profile

›Ascent characteristics

›Altitude reached — unusual below 3,000 m

›Risk increases substantially above 3,500-4,500 m

›Extreme risk above 5,000 m

›Rate of ascent — strongest modifiable risk factor

›Rapid ascent (e.g., flying to high-altitude resort) most dangerous

›Failure to follow gradual ascent guidelines

›Sleeping altitude

›Onset typically on 2nd night at new altitude

›Symptoms often worsen during sleep

›Timeline of symptom onset

›Usually 2-4 days after ascent above 2,500-3,000 m

›Rarely occurs after more than 4 days at a given altitude

Symptom characterization

›Early symptoms

›Decreased exercise performance disproportionate to altitude or fitness

›First and most sensitive early sign

›Often dismissed as altitude adjustment

›Exertional dyspnea

›Disproportionate to activity level

›Progresses more rapidly than typical altitude fatigue

›Dry cough

›May become productive as illness advances

›Gurgling sensation in chest

›Fatigue and weakness

›Late and severe symptoms

›Dyspnea at rest

03Physical Exam/exam63

Vitals and general appearance

›Vital signs snapshot

›SpO2 — hallmark finding

›Values of 50-70% in severe HAPE

›At least 10 points below expected for healthy individuals at same altitude

›Respiratory rate

›Tachypnea almost universal

›Increasing rate is a severity and fatigue marker

›Heart rate

›Resting tachycardia universal

›Worsens markedly with any exertion

›Temperature

›Low-grade fever up to 38.5 C is common — can mimic pneumonia

›High fever more suggestive of infectious etiology

›Blood pressure

›Typically preserved initially

›Hypotension indicates severe decompensation

›General appearance

›Work of breathing

›Accessory muscle use

›Inability to speak full sentences

›Cyanosis

›Central — lips, tongue, mucous membranes

›Peripheral — fingernails and toe nails

Pulmonary exam

›Lung auscultation

›Rales — classic and diagnostic

›Begin in right axilla (right middle and lower lobes preferentially affected)

04Differential Diagnosis/ddx44

Life-threatening mimics

›Cardiogenic pulmonary edema

›ICD-10 I50.1

›Distinguishing features: orthopnea, elevated JVP, S3, cardiomegaly, Kerley B-lines, elevated BNP

›HAPE: normal heart size, low BNP, noncardiogenic pattern

›Pulmonary embolism

›ICD-10 I26.99

›Distinguishing features: pleuritic chest pain, unilateral leg swelling, VTE risk factors

›HAPE: no pleuritic pain, bilateral infiltrates, altitude context

›Myocardial infarction

›ICD-10 I21.9

›Distinguishing features: chest pain, ST changes, troponin elevation

›ECG and troponin required to exclude

›Tension pneumothorax

›ICD-10 J93.0

›Distinguishing features: sudden pleuritic pain, absent unilateral breath sounds, tracheal deviation

Infectious mimics

›Pneumonia — community acquired

›ICD-10 J18.9

›Distinguishing features: fever above 38.5 C, purulent sputum, focal consolidation

›Distinction difficult — HAPE causes low-grade fever and leukocytosis

›HAPE: bilateral patchy infiltrates, altitude context, no productive purulent sputum early

›Viral upper respiratory tract infection

›Rhinorrhea, sore throat

›Milder hypoxemia compared to HAPE

›Bronchitis

›Productive cough without alveolar infiltrates

›Normal SpO2

05Laboratory Tests/lt38

Oxygenation and gas exchange

›Pulse oximetry — essential field and hospital monitoring

›SpO2 at least 10 points below expected for altitude strongly suggests HAPE

›Values of 50-70% in severe HAPE

›Continuous monitoring for trend

›Arterial blood gas

›Respiratory alkalosis with severely low PaO2 in mmHg

›PaO2 alarmingly low relative to altitude-expected values

›Low PaCO2 from compensatory hyperventilation

›Hemoglobin saturation confirms SpO2 oximetry reading

›A-a gradient calculation for severity assessment

Cardiac biomarkers

›BNP or NT-proBNP

›Expected to be low or normal in HAPE

›Helps rule out cardiogenic pulmonary edema

›Elevated BNP favors heart failure

›Not routinely ordered in field settings

›Troponin

›Exclude myocardial infarction

›RV strain can cause troponin elevation in severe HAPE

›Rising trend warrants cardiology input

Infection and inflammation

›Complete blood count

›WBC count usually elevated — nonspecific

›Leukocytosis does not confirm pneumonia over HAPE

›Leukopenia would favor viral or sepsis

›Hemoglobin — polycythemia in acclimatized individuals

›Procalcitonin

06Diagnostic Tests/dt73

Scoring Systems

›Lake Louise Acute Mountain Sickness Score

›Headache plus at least one other symptom: GI, fatigue, dizziness, sleep disturbance

›Score 0-15; score >= 3 with headache = AMS

›Useful for screening concurrent AMS in HAPE patients

›Does not specifically diagnose HAPE

›2018 revised Lake Louise Score excludes sleep disturbance

›Headache mandatory for AMS diagnosis

›Score >= 3 = AMS

›HAPE Severity Grading (Lake Louise HAPE Score)

›Grade 1 Mild HAPE

›Exertional dyspnea, dry cough, reduced exercise tolerance

›SpO2 mildly reduced; rales in one lung field only

›Grade 2 Moderate HAPE

›Dyspnea with minimal exertion, bilateral rales

›Cyanosis, SpO2 moderate reduction

›Grade 3 Severe HAPE

›Dyspnea at rest, pink frothy sputum

›SpO2 <50-60%, concurrent HACE, respiratory distress

MRI

›MRI chest — not routinely indicated for HAPE

›Research tool for studying pulmonary edema distribution

›Demonstrates bilateral heterogeneous edema pattern

›Predominantly involves right middle and lower lobes

›Not practical in field or acute settings

›CT and CXR preferred for clinical decision-making

›Brain MRI if concurrent HACE suspected

›White matter changes and corpus callosum lesions reported in HACE

›Posterior reversible encephalopathy pattern may occur

›CT chest — use when clinical diagnosis uncertain or alternative diagnosis suspected

›Indications

›Initial evaluation unrevealing or PE suspected

›Failure to improve despite appropriate treatment

›Suspected alternative diagnosis (PE, pneumonia, pneumothorax)

›Typical HAPE findings on CT

›Patchy bilateral ground-glass opacities

›Peripheral and lower lobe predominance

›Normal heart size — distinguishes from cardiogenic edema

›No pleural effusions, no Kerley B-lines

›CT pulmonary angiography

›Indicated when PE cannot be excluded clinically

›Sensitivity for PE 83-96%, specificity 86-97%

›CT head

›Concurrent HACE with neurologic symptoms

›Excludes intracranial hemorrhage, infarction

Ultrasound

›Lung ultrasound — POCUS in field and hospital settings

›B-lines

›Vertical reverberation artifacts arising from pleural line

›Three or more B-lines per intercostal space = B-pattern (pulmonary edema)

›Sensitive for pulmonary edema but nonspecific for HAPE vs cardiogenic

›No accepted threshold for HAPE diagnosis

›Protocol

›Bilateral anterior and lateral chest — 8-zone or 12-zone approach

›Confluent bilateral B-lines in HAPE

›Cardiac views

›RV dilation and strain in severe HAPE

›Rule out pericardial effusion

›IVC assessment for volume status

›Preserved LV function — distinguishes from cardiogenic edema

›Chest X-ray — first-line imaging in well-resourced settings

›Classic HAPE findings

›Patchy alveolar infiltrates — right middle and lower lobes early

›Bilateral infiltrates in moderate-severe HAPE

›Normal heart size — key distinguishing feature from cardiogenic edema

›Prominent pulmonary arteries

›Absent findings that suggest alternative diagnosis

›No cardiomegaly

›No Kerley B-lines

›No pleural effusions

›No focal lobar consolidation (more typical of pneumonia)

›Echocardiography

›Not routinely needed in typical HAPE presentation

›Consider when underlying cardiac pathology or pulmonary hypertension suspected

›Patent foramen ovale evaluation in recurrent HAPE

›RV systolic pressure estimation by Doppler

07Disposition/dispo43

Admission criteria

›Hospital admission indications

›Severe HAPE — SpO2 fails to improve above 90% within 5 minutes of high-flow O2

›ICU level monitoring

›Potential for mechanical ventilation

›Concurrent HACE — altered mental status, ataxia

›Dual-pathway treatment required

›Closer neurologic monitoring

›Hemodynamic instability

›SBP < 90 mmHg not responding to initial measures

›Progressive tachycardia unresponsive to O2

›Failure to improve with O2, rest, and nifedipine over 4-6 hours

›Consider alternative diagnosis

›Escalate to higher level care

Observation and discharge criteria

›Observation at mountain clinic or ski resort medical facility

›Mild-to-moderate HAPE with monitoring capability and O2 availability

›Can observe for 48-72 hours

›Stable or improving SpO2 trend on supplemental O2

›Prerequisites for observation

›Access to continuous O2

›Nursing monitoring available

›Rescue descent plan in place

›Discharge criteria

›SpO2 >90% on supplemental O2 with stable or improving trajectory

›Trending toward normal for altitude

›No resting tachypnea

›Adequate support system

08Treatment/t96

Oxygen therapy

›Supplemental O2 — first-line and highest priority

›Dose: 2-4 L/min by nasal cannula or face mask

›Target SpO2 >90%

›Titrate upward as needed for severe hypoxemia

›High-flow O2 via non-rebreather mask in severe cases

›Mechanism

›Reverses hypoxic pulmonary vasoconstriction

›Reduces pulmonary artery pressure by 30-50%

›Monitoring response

›SpO2 should begin improving within minutes

›Failure to reach >90% within 5 minutes indicates severe HAPE

›SpO2 >90% is therapeutic target

Descent

›Descent — mandatory treatment in field settings

›Target: minimum 300-1,000 m descent

›Physiologically equivalent to supplemental O2

›Should accompany O2 whenever possible

›Execution

›Begin descent immediately on diagnosis

›Minimize patient exertion during descent

›Continue O2 during descent if available

›Gamow bag (portable hyperbaric chamber)

›Increases effective O2 delivery equivalent to 1,500-2,500 m descent

›Used when descent impossible and O2 unavailable

›Inflate to 2 psi; repeat sessions as needed

Pharmacotherapy

›Nifedipine — primary pharmacotherapy for HAPE

›Indication: field setting when O2 unavailable; hospital adjunct when O2 alone insufficient

›Pulmonary vasodilator — reduces hypoxic pulmonary vasoconstriction

›Class I recommendation for field treatment when O2 unavailable

›Dosing — nifedipine sustained-release

›30 mg orally every 12 hours

›Alternative: immediate-release nifedipine 10 mg load, then extended-release 20 mg every 6 hours

›Monitoring

›Blood pressure — risk of systemic hypotension

›SpO2 response within 30-60 minutes

›Contraindications and precautions

›Systemic hypotension (SBP < 90 mmHg)

›Do not combine with other pulmonary vasodilators

›PDE-5 inhibitors — alternative if nifedipine unavailable

›Tadalafil

›10 mg orally every 12 hours

›Evidence: reduces pulmonary artery pressure at altitude

›WMS 2019 guideline endorsement for prophylaxis; role in treatment less established

›Sildenafil

›50 mg orally every 8 hours

›Alternative when tadalafil unavailable

›Do not combine multiple pulmonary vasodilators

›Risk of severe systemic hypotension

›No proven additive pulmonary benefit

›Dexamethasone — add only if concurrent HACE suspected

›Loading dose 8 mg IV, IM, or orally

›Maintenance 4 mg every 6 hours

›No established role in HAPE treatment without HACE

›Mechanism in HACE: reduces cerebral edema

›May have adjunct benefit via improving respiratory drive

›Contraindicated as sole HAPE treatment without concurrent HACE

Non-pharmacologic adjuncts

›Strict rest

›Bed rest throughout treatment phase

›Exertion acutely raises pulmonary artery pressure

›Even mild activity can worsen oxygenation significantly

›Warm environment

›Cold exposure raises pulmonary artery pressure via sympathetic activation

›Insulate patient during descent if outdoors

›CPAP — adjunct in hospital settings

›Indication: inadequate SpO2 response to supplemental O2 alone

›CPAP pressure 5-10 cmH2O as starting range

›Improves alveolar recruitment and gas exchange

›Not practical in field settings

›May reduce need for intubation in moderate HAPE

Contraindicated or not recommended treatments

›Diuretics — no role in HAPE treatment

›HAPE is noncardiogenic — diuresis ineffective and potentially harmful

›May worsen dehydration at altitude

›No evidence of benefit

›Acetazolamide — no established role in HAPE treatment

›Effective for AMS prevention but not HAPE treatment

›Recent evidence inconclusive for HAPE prevention

›WMS 2024 guidelines do not recommend for HAPE

›Beta-agonists — no established role in HAPE treatment

›No evidence of clinical benefit for HAPE

›Routine diuretics and fluid restriction

›Unlike cardiogenic edema, fluid restriction not indicated

›Maintain adequate hydration

Prophylaxis for high-risk individuals

›Nifedipine prophylaxis — first-line prevention

›Nifedipine SR 30 mg every 12 hours

›Start day before planned ascent

›Continue for 24-48 hours after reaching target altitude

›Indicated for individuals with prior HAPE history

›Tadalafil — alternative prophylaxis

›10 mg every 12 hours starting day before ascent

›WMS 2024 guideline alternative

›Dexamethasone — alternative prophylaxis

›8 mg every 12 hours starting day before ascent

›Alternative when vasodilators contraindicated or unavailable

›Gradual ascent — non-pharmacologic prevention

›Ascend no more than 300-500 m sleeping altitude per day above 3,000 m

›Rest day every 3-4 days

›Allows pulmonary vascular acclimatization

09Special Populations/sp76

Pregnancy

›Physiologic changes affecting HAPE risk in pregnancy

›Increased baseline respiratory rate and tidal volume

›Lower baseline PaCO2 in mmHg (28-32 mmHg)

›Relative alkalosis at baseline

›Increased cardiac output (30-50% above non-pregnant)

›May alter pulmonary hemodynamic response to hypoxia

›Diaphragm elevation from gravid uterus

›Reduced functional residual capacity

›Less respiratory reserve

›HAPE in pregnancy — management approach

›Supplemental O2 — safe and highest priority

›Target SpO2 >95% in pregnancy (fetal safety)

›Higher threshold than non-pregnant adults

›Immediate descent — mandatory

›Fetal hypoxemia risk from maternal SpO2 <90%

›Air travel descent if required

›Nifedipine safety in pregnancy

›Category C — used for tocolysis in obstetrics

›Limited evidence specific to HAPE in pregnancy

›Risk-benefit discussion required; severe HAPE may justify use

›Avoid tadalafil and sildenafil in pregnancy

›Limited safety data

›Potential teratogenic concern

›Obstetric consultation early in any pregnant patient at altitude with HAPE

Geriatric

›Age-related physiologic factors

›Reduced hypoxic ventilatory response with aging

›Blunted protective respiratory drive

›Greater severity of hypoxemia for given altitude

›Higher baseline prevalence of cardiovascular comorbidities

›Hypertension, coronary artery disease, heart failure

›Confounds HAPE diagnosis

›Reduced physiologic reserve

›Less tolerance of hypoxemia-induced cardiac stress

›Faster decompensation

›Medication considerations in older adults

›Nifedipine — increased risk of hypotension

›Start at lower end of dosing range

›Monitor blood pressure closely

›More susceptible to reflex tachycardia

›Polypharmacy interactions

›Nifedipine interactions with antihypertensives

›CYP3A4 drug interactions with nifedipine

›Renal function — dose adjustment consideration

›Reduced drug clearance

›More cautious titration

›Diagnostic challenges in geriatric patients

›Cardiogenic edema more likely at baseline — higher BNP threshold needed

›Atypical presentation more common

›Confusion or weakness may dominate over dyspnea

›Lower threshold for ECG and troponin

Pediatrics

›Unique susceptibility factors in children

›Greater HAPE susceptibility compared to adults per body weight

›Exact mechanism unclear — may relate to ventilatory response

›Upper respiratory tract infections in children markedly increase risk

›Faster disease progression

›Lower reserve and faster decompensation

›Early recognition critical

›Re-entry HAPE

›Children descending and reascending to home altitude at risk

›Well documented in Himalayan communities

›Weight-based dosing and treatment modifications

›Supplemental O2 — first-line as in adults

›Target SpO2 >90%

›Pediatric mask sizing

›Nifedipine in children

›Limited evidence — off-label use

›Estimated dosing 0.2-0.5 mg/kg per dose orally up to adult dose

›Immediate descent preferred over pharmacotherapy

›Dexamethasone for concurrent HACE in children

›0.15 mg/kg IV or orally up to 8 mg loading dose

›0.1 mg/kg every 6 hours maintenance

›Clinical presentation in children

›Refusal to walk or play — early exertional intolerance sign

›Crying and irritability from headache or hypoxemia

›Cough and rapid breathing — often attributed to viral URI

›SpO2 monitoring critical for differentiation

10Background/b84

Epidemiology

›Incidence and altitude thresholds

›Incidence varies by ascent rate and altitude

›0.2-2% of altitude travelers overall

›Up to 15% with very rapid ascent to high altitudes

›Unusual below 3,000 m

›Most cases between 3,500-5,500 m

›Leading cause of death from high-altitude illness

›Estimated untreated mortality 50%

›With treatment (O2 + descent) mortality drops dramatically

›Most deaths occur during night due to sleep-associated worsening

›Population demographics

›Affects fit, healthy young adults who ascend rapidly

›Recreational trekkers, mountaineers, skiers

›Military personnel at high altitude

›High-altitude residents returning after low-altitude travel (re-entry HAPE)

›Mortality data

›Without treatment: 50% mortality in severe HAPE

›Rapid clinical deterioration within hours

›Death from hypoxemia-induced cardiorespiratory failure

›With appropriate treatment: survival rate >90% in treated patients

›Recovery typically occurs within hours of descent and O2

›Radiographic clearing within days

Pathophysiology

›Core mechanism — noncardiogenic pulmonary edema

›Hypoxic pulmonary vasoconstriction

›Hypoxia triggers pulmonary artery vasoconstriction

›Elevates pulmonary artery pressure

›Inhomogeneous vasoconstriction — some segments over-perfused

›Over-perfused capillaries develop stress failure

›Capillary stress failure

›Excessively high capillary pressure exceeds structural limits

›Noninflammatory, hemorrhagic alveolar-capillary leak

›BAL fluid: protein-rich, red blood cells, not inflammatory cells

›Distinguishes HAPE from ARDS (which is inflammatory)

›Individual susceptibility

›HAPE-susceptible individuals have exaggerated hypoxic pulmonary vasoconstriction

›Lower hypoxic ventilatory response

›Smaller caliber pulmonary vasculature proposed

›Physiological cascade

›Altitude exposure — hypoxemia

›Low PaO2 at altitude

›Hypoxic pulmonary vasoconstriction triggered

›Pulmonary hypertension

›Uneven vasoconstriction creates high-pressure segments

›Capillary hydrostatic pressure exceeds 25-30 mmHg

›Alveolar flooding

›Protein-rich edema fluid in alveoli

›Impaired gas exchange — worsening hypoxemia

›Positive feedback loop — more hypoxemia, more vasoconstriction

›Role of patent foramen ovale

›PFO allows right-to-left shunting under elevated RA pressure

›Worsens systemic hypoxemia

›HAPE-susceptible individuals have higher prevalence of PFO

›Estimated 2-fold increased risk with PFO

Therapeutic Considerations

›Treatment hierarchy

›Priority order: descent + O2 > nifedipine > gamow bag

›O2 most rapidly effective — reverses cause (hypoxic vasoconstriction)

›Nifedipine adjunct — pulmonary vasodilator

›Gamow bag — substitute for descent when physically impossible

›Evidence basis for nifedipine

›Randomized controlled trial evidence for prophylaxis

›Observational evidence for treatment

›WMS 2024 guideline — Class I for HAPE-susceptible patients ascending to risk altitudes

›Why diuretics fail

›Edema is pressure-driven, not sodium-water excess

›Loop diuretics worsen dehydration without reducing pulmonary pressure

›Worsening hemoconcentration may paradoxically worsen pulmonary pressure

›Mechanism distinct from cardiogenic pulmonary edema

›No fluid overload — just maldistributed pressure

›Why acetazolamide does not treat HAPE

›Mechanism: promotes renal bicarbonate excretion, stimulates ventilation

›Benefits AMS through improved ventilation and acclimatization

›Does not lower pulmonary artery pressure

›No effect on hypoxic pulmonary vasoconstriction

›2022 RCT: acetazolamide did not reduce pulmonary artery pressure vs placebo on rapid ascent to 4,559 m

›Oxygen physiologic mechanism

›Reverses hypoxic pulmonary vasoconstriction directly

›Rapidly reduces pulmonary artery pressure by 30-50%

›Begins within minutes of administration

›Sufficient alone in mild-moderate HAPE with bed rest

›More effective than any pharmacotherapy as monotherapy

›Future therapeutic directions

›Inhaled nitric oxide — research setting, potent selective pulmonary vasodilator

›Beta-2 agonists — theoretical benefit via Na+ channel activation; clinical trials negative

›Salmeterol inhalation — prophylaxis studies showed partial benefit but not recommended

11Patient Discharge Instructions/pdi42

copy discharge instructions

›What is High Altitude Pulmonary Edema

›Fluid buildup in the lungs caused by rapid ascent to high altitude

›Occurs in healthy people without warning

›Not caused by heart disease

›Typically develops within 2-4 days of arriving at a new altitude

›Most often during the second night at a new altitude

›Symptoms often worsen during sleep

›Medications prescribed

›Nifedipine — if prescribed

›Take as directed: 30 mg extended-release tablet twice daily

›May cause low blood pressure — rise slowly from sitting

›Do not stop without medical advice

›Carry supply for future ascents as prophylaxis

›Supplemental oxygen — if prescribed

›Use as directed to maintain oxygen levels

›Do not adjust flow without medical advice

›Activity and altitude restrictions

›No reascent until completely symptom-free

›SpO2 stable at rest and with gentle activity without oxygen or medications

›Typically at least 1-2 days of full recovery required

›Gradual reascent if resuming altitude activities

›No more than 300-500 m sleeping altitude per day above 3,000 m

›Rest day every 3-4 days

›Avoid alcohol and sedating medications at altitude

›Worsen breathing during sleep

›Can mask early symptoms

›Return to emergency department immediately for

12References/r28

Guidelines and key sources

›Bartsch P, Swenson ER. Acute High-Altitude Illnesses. New England Journal of Medicine. 2013

›Comprehensive review of HAPE pathophysiology, clinical features, and management

›Primary source for incidence, mortality, and clinical features used in this document

›Hackett PH, Roach RC. High-Altitude Illness. New England Journal of Medicine. 2001

›Classic clinical overview including diagnosis, treatment hierarchy

›Basis for oxygen and nifedipine treatment protocols

›Luks AM, Beidleman BA, Freer L, et al. Wilderness Medical Society Clinical Practice Guidelines for the Prevention, Diagnosis, and Treatment of Acute Altitude Illness: 2024 Update. Wilderness and Environmental Medicine. 2024

›Current authoritative clinical guidelines from WMS

›Covers nifedipine, tadalafil, dexamethasone prophylaxis protocols

›Addresses acetazolamide ineffectiveness for HAPE

›Luks AM, Auerbach PS, Freer L, et al. Wilderness Medical Society Clinical Practice Guidelines: 2019 Update. Wilderness and Environmental Medicine. 2019

›Previous iteration of WMS guidelines

›PDE-5 inhibitor prophylaxis recommendations

›Swenson ER. Early Hours in the Development of HAPE: Time Course and Mechanisms. Journal of Applied Physiology. 2020

›Pathophysiologic cascade and SpO2 diagnostic thresholds

›Alarm features and field diagnostic criteria

›Berger MM, Sareban M, Schiefer LM, et al. Effects of Acetazolamide on Pulmonary Artery Pressure After Rapid Active Ascent to 4,559 m. Journal of Applied Physiology. 2022

›RCT evidence that acetazolamide does not reduce pulmonary artery pressure

›Basis for acetazolamide not recommended for HAPE

Diagnostic and imaging references

›Rabold M. High-Altitude Pulmonary Edema: A Collective Review. American Journal of Emergency Medicine. 1989

›CXR findings in HAPE including right-sided predominance

›Radiographic features distinguishing HAPE from cardiogenic edema

›Gluecker T, Capasso P, Schnyder P, et al. Clinical and Radiologic Features of Pulmonary Edema. Radiographics. 1999

›Radiographic comparison of cardiogenic vs noncardiogenic pulmonary edema

›Reference for CT and CXR interpretation

›Peter H. Hackett and David R. Shlim. High-Altitude Travel and Altitude Illness. CDC Yellow Book. 2025

Learn More: High Altitude Pulmonary Edema (HAPE)→

Comprehensive Clinical Review

Structured, evidence-informed, long-form analysis for deeper understanding.

Evidence & Review

Reviewed by SymptomDx Medical Team · Last reviewed August 18, 2026

SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.