Return to High Altitude Activity Return to High Altitude Activity

After High Altitude IllnessAfter High Altitude IllnessKevin deWeber, MD, FAAFPKevin deWeber, MD, FAAFP

Director, Director,

Primary Care Sports Medicine FellowshipPrimary Care Sports Medicine Fellowship

MilitarySports Medicine

Fellowship

“Every Warrior an Athlete”

ObjectivesObjectives

• Review pathophysiology of high altitude illness (HAI)

• Review the types of HAI and how they are treated

• Review factors predisposing to HAI• Discuss preventive treatment for those

with a remote history of HAI• Discuss factors in return-to-altitude

decisions after recent HAI

PreviewPreview

• Little evidence for recommendations of return to altitude activity after HAI

• Acclimatization and slow ascent are powerful– Ascend < 600 m/day– Rest day every 600 – 1200 m

• Prophylactic meds advised if unable to comply• Consider neuro-psych deficits from moderate

AMS/HACE and their effect on activity

Environment at high altitudeEnvironment at high altitude(>1500 m or 4920 ft)(>1500 m or 4920 ft)

• Barometric pressure decreases

• Partial pressure of oxygen decreases

• RESULT: “Hypobaric Hypoxia”– Lower alveolar O2

leads to lower SaO2

Pikes Peak, 14,110 ft (4300 m)

US Air Force Academy, ~7,000 ft

Ft. Carson, CO, ~6500 ft

Acclimatization = body’s adaptation Acclimatization = body’s adaptation to hypobaric hypoxiato hypobaric hypoxia

AcclimatizationAcclimatization

• Immediate (minutes to hours)– ↑ Sympathetic tone ↑ HR & CO– ↑ Ventilation ↑ PaO2 and ↓ PaCO2 ↓ pH– Renal bicarbonate diuresis (to balance pH)– ↑ Pulmonary artery pressure ↑ O2

absorption

• Delayed (days to weeks)– Erythropoietin ↑ RBC production– Remodeling of pulmonary arterioles

Altitude Illnesses Altitude Illnesses (Failure to Acclimatize)(Failure to Acclimatize)

• Cerebral Syndromes– Acute Mountain Sickness (AMS)– High Altitude Cerebral Edema (HACE)

mild AMS moderate AMS HACE

• Pulmonary Syndrome– High Altitude Pulmonary Edema (HAPE)

• Importance– HACE and HAPE can be fatal

Acute Mountain SicknessAcute Mountain Sickness(AMS)(AMS)

• Defined as HEADACHE plus one or more symptom:– Anorexia, nausea or vomiting– Fatigue or weakness– Dizziness or lightheadedness– Difficulty sleeping

Effects of AMS on performanceEffects of AMS on performance

• Mild: annoyance only

• Moderate: impaired concentration, memory, speech, and physical performance; – Can be disabling– Subtle abnormalities visible on MRI– Effects can last weeks

High Altitude Cerebral EdemaHigh Altitude Cerebral Edema(HACE)(HACE)

• AMS symptoms plus ALTERED L.O.C. and ATAXIA• Other neuro findings possible• Coma develops• Death results if untreated

• Pathophysiology– altered cerebral vascular permeability

leads to brain swelling– MRI: cerebral edema,

lesions of corpus callosum

High Altitude Pulmonary EdemaHigh Altitude Pulmonary Edema(HAPE)(HAPE)

• Defined by two pulmonary symptoms…– Cough, dyspnea at rest, exercise intolerance,

chest tightness/congestion…

• and two pulmonary signs…– Crackles, wheezing, cyanosis, tachypnea,

tachycardia

• Most common cause of death among HAI– 50% mortality rate if not treated quickly

High Altitude Pulmonary EdemaHigh Altitude Pulmonary Edema(HAPE)(HAPE)

• CXR findings– Blotchy fluffy infiltrates

• PathophysiologyHypoxia

pulmonary artery hypertension

alveolar damage

edema and hemorrhage into alveoli

Risk factors for HAIRisk factors for HAI

• Rapid gain in altitude• Prior history of HAI

– genetic factors involved

• Alcohol, sedatives• HAPE: cold ambient

temperature• Strenuous exercise

HAI Protective FactorsHAI Protective Factors

• Residence at elevation >900 m (2950 ft)

• Slow gain in elevation– <600 m (1970 ft) per day in sleeping elevation

• Genetic factors

• Vigorous fluid intake

• Physical fitness NOT protective

Treating HAITreating HAI

• Rest, halt ascent

• Descent– Moderate AMS: >500 m (1640 ft)– HACE: > 1000 m (3280 ft)– HAPE: 500 – 1000 m

• Oxygen if available

• Keep warm (esp. for HAPE)

• Portable hyperbaric chambers

Portable Altitude Chamber® (PAC)

Gamow® bag Certec® bag

Treating HAI (cont.)Treating HAI (cont.)

• Acetazolamide– Speeds acclimatization– 75% effective in preventing AMS– Treats moderate AMS & HACE– Dose: 125-250 mg BID

Treating HAI (cont.)Treating HAI (cont.)

• Dexamethasone– Decreases cerebral edema– Treats moderate AMS and

HACE– Prevents AMS, ? HACE– Dose

• 2 mg po/IM/IV QID• 4 mg BID

Treating HAI (cont.)Treating HAI (cont.)

• Nifedipine– Decreases pulmonary artery

pressure– Prevents and treats HAPE– Dose: 20 – 30 mg extended

release BID

Treating HAI (cont.)Treating HAI (cont.)

• Salmeterol– Decreases alveolar fluid

transport– Prevents and treats HAPE– Dose: 125 mcg inhaled BID

Considerations for Considerations for Return to Altitude Activity after HAIReturn to Altitude Activity after HAI

• Severity and type of prior HAI

• Future ascent requirements

• Feasibility of descent/extra rest days if needed

• Availability of medical treatments

Two scenarios for Two scenarios for Return to Altitude Activity after HAIReturn to Altitude Activity after HAI

1. Remote history of HAI, fully recovered

2. Recent HAI, with/without recovery

1. Remote history of HAI, 1. Remote history of HAI, fully recoveredfully recovered

• Proper acclimatization protocols are paramount– Ascend no more than 600 m (1970 ft) per day

in sleeping altitude when >2500 m (8200 ft)– Spend one extra night every 600-1200 m

(1970 – 3937 ft)– Avoid abrupt ascent to >3000 m (9843 ft)– Spend 2-3 nights at 2500-3000 m before

ascending further

““Acute mountain sickness: influence of Acute mountain sickness: influence of susceptibility, preexposure, and ascent rate”susceptibility, preexposure, and ascent rate”

58

3329

7

0

10

20

30

40

50

60

Incidence of AMS (%) during ascent to 4559 m in persons with a prior history of AMS

Normal ascent rateand no pre-exposure

Slow ascent

Pre-exposure

Pre-exposure ANDslow ascent

Schneider M et al. Med Sci Sports Exerc 2002

Prevention of recurrent AMSPrevention of recurrent AMS

• Proper acclimatization, slow ascent. If not possible…

• Acetazolamide 125-250 mg po BID starting 1 day prior to ascent, continuing until at max altitude for 2 days. If not possible…

• Alternate: Dexamethasone 2 mg po QID or 4 mg BID, starting 1 day prior, cont. until at max altitude 2 days

• Unknown which is better or if combination therapy is indicated

Prevention of recurrent HACEPrevention of recurrent HACE

(No evidence-based recommendations)

• Strong recommendation for acclimatization and slow ascent. If not possible, or descent/medical treatment not

possible…

• Prophylaxis with acetazolamide or dexamethasone, as for AMS

Prevention of recurrent HAPEPrevention of recurrent HAPE

• The power of slow ascent: case series– 4 climbers with history of 2-4 prior cases of

HAPE each– Made a collective 7 ascents to > 5000 m

(16,400 ft)– Acclimatized fully– Ascended only 330-350 m (984-1150 ft) a day– RESULT: no cases of HAPE (100% effective)

Bärtsch P et al. High altitude pulmonary edema. Respiration 1997

Prevention of recurrent HAPEPrevention of recurrent HAPE(cont.)(cont.)

• The power of meds: 1 R, DB, PC trial comparing prophylactic meds– Dex 8 mg bid– Tadalafil 10 mg bid

• Dex & tad vs placebo: – P < 0.001 & < 0.007– Dex vs tab: not sig

• Both dex & tad reduced pulmonary artery pressure

0

10

20

30

40

50

60

70

80

Placebo Tadalafil

% w/ HAPE

Prophylaxis for recurrent HAPEProphylaxis for recurrent HAPE

• Strong recommendation for acclimatization and slow ascent. If not possible, or descent/medical treatment not

possible…

• Prophylactic options:– Tadalafil 10 mg po bid– Dexamethasone 8 mg po bid– Acetazolamide 125-250 mg po BID– Salmeterol 125 mcg inhaled BID– Nifedipine 20-30 mg XR BID

– All beginning 1 day before ascent

No evidence of superiority of one

agent or risks/benefits of

combination therapy

2. Return to Altitude Activity after 2. Return to Altitude Activity after RecentRecent HAI HAI

• Considerations (same as remote HAI hx)– Severity and type of prior HAI– Future ascent requirements– Feasibility of descent/extra rest days if needed– Availability of medical treatments

• Additional considerations for recent HAI– Should the patient fully recover before returning to

altitude/activity?– How safe is continued activity at altitude?– Should activities be limited?

Treatment of Mild AMSTreatment of Mild AMS

• Descend > 500 m (1640 ft) OR

• Rest 1-2 days at same altitude

• Oxygen 12-24 hours, if available

• Consider acetazolamide 125-250 mg po BID

• Symptomatic treatment with analgesics, anti-emetics

Return to Altitude Activity during/after Return to Altitude Activity during/after Mild AMSMild AMS

(No evidence-based recommendations)

• Common practice: continue activity despite symptoms

• Risks• Impaired cognition/performance• Progression to moderate AMS or HACE

• Consider acetazolamide

““To air is human: altitude illness during To air is human: altitude illness during an expedition length adventure racean expedition length adventure race””

• 10-day, 238-mile race at elevations of 9,500 – 13,500 ft

• No prophylaxis allowed

• 33 cases of AMS treated during race– 88% were returned to race– 58% finished race (compared to 74% overall)

• CONCLUSION: untreated AMS probably reduces athletic performance

Talbot TS et al. Wilderness Environ Med 2004

Treatment of Treatment of ModerateModerate AMS AMS

• Descend >500 m

• Rest 1-2 days

• Do not allow continued ascent/activity– Significant performance/cognition decrement– Risk of progression to HACE

• Oxygen 1-2 days, if available

• Acetazolamide; dex as alternate

Return to Altitude Activity after recovery Return to Altitude Activity after recovery from Moderate AMSfrom Moderate AMS

(No evidence-based recommendations)

• Strict adherence to acclimatization and slow ascent protocols– Ascend no more than 600 m/day– Rest day every 600 – 1200 m

• Consider acetazolamide (or dex)

• Counsel on recognition and rapid treatment of HACE/HAPE

Treatment of HACETreatment of HACE

• Immediate descent > 1000 m and hospitalize

• Oxygen to maintain SaO2 >90%

• Dexamethasone—8 mg PO/IM/IV initially followed by 4 mg QID

• Portable hyperbaric therapy if descent impossible

Treatment of HACE (cont.)Treatment of HACE (cont.)

• Management of coma– Bladder catheterization– Airway control

• Diagnostic studies– CXR to rule out concurrent HAPE– MRI to rule out other conditions

Recovery from HACE:Recovery from HACE:highly variablehighly variable

• 1-3 days for symptoms to resolve

• Days to 12 weeks for neuropsychological function to normalize

• 3-4 weeks for papilledema to resolve

• Days to 5 weeks for MRI to normalize

Return to Altitude Activity after Return to Altitude Activity after recovery from HACErecovery from HACE

(No evidence based recommendations)

• Full recovery highly advised

• Strict adherence to acclimatization and slow ascent protocols– Ascend < 600 m/day– Rest day every 600 – 1200 m

• Consider prophylaxis– Acetazolamide; dex as alternate

Treatment of HAPETreatment of HAPE

• Immediate descent 500-1000 m

• Oxygen to keep SaO2 >90%.

• If descent/O2 not immediately available…

– Portable hyperbaric therapy– Nifedipine 20-30 mg extended release BID

(avoid if concomitant HACE) and/or…– Salmeterol 125 mcg inhaled

Treatment of HAPE (cont.)Treatment of HAPE (cont.)

• Admit if:– >4L/min O2 requirement

– Elderly, very young– Concomitant HACE or co-morbid cardio-

pulmonary disease• Dexamethasone if concomitant HACE

• Low-flow outpatient O2 for others; check daily

Recovery from HAPERecovery from HAPE

• Variable; little evidence in literature

• May take 2 weeks to recover strength

• Resume some activity when SaO2 > 90% without supplemental O2

• Remaining at some altitude fosters acclimatization via pulmonary arteriolar remodeling

““Reascent following resolution of high Reascent following resolution of high

altitude pulmonary edema (HAPE).”altitude pulmonary edema (HAPE).” • Case reports of 3 mountaineers with HAPE• Treated with…

– descent to lower altitude– oxygen– rest 2-3 days

• Resumed ascent; no prophylaxis– < 600 m/day ascent; several rest days

• RESULT: all reached peaks w/o HAPE– One reached summit of Mt. Everest at 8850 m

(29,035 ft)

Litch JA, Bishop R. High Alt Med Biol 2001 Spring;2(1):53-5

Return to Altitude Activity after Return to Altitude Activity after recovery from HAPErecovery from HAPE

(No evidence based recommendations)• Strict adherence to acclimatization and

slow ascent protocols– Ascend < 300 - 600 m/day– Rest day every 600 – 1200 m

• Consider prophylaxis:– acetazolamide and/or– nifedipine or salmeterol (especially if ascent will be > 600 m/day)

ReviewReview

• Little evidence for recommendations of Return to Altitude Activity after HAI

• Acclimatization and slow ascent are powerful– Ascend < 600 m/day– Rest day every 600 – 1200 m

• Prophylactic meds advised if unable to comply• Consider neuro-psych deficits from moderate

AMS/HACE and their effect on activity

Thank you!Thank you!