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High altitude syndrome
 

High altitude syndrome

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kanjanee wachirarangsiman R3

kanjanee wachirarangsiman R3

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    High altitude syndrome High altitude syndrome Presentation Transcript

    • High altitude medical problem
    • 2,031m 2,102 m 2,195 m2,285 m
    • Altitude Height EffectIntermediate 1520 - 2440 m exercise performancealtitude (5000 - 8000 ft) alveolar ventilation ↔arterial oxygen transportHigh altitude >2440 m (>8000 ft) AMSVery high 4270 - 5490 m (14,000 - 18,000 AMSaltitude ft)
    • PATHOPHYSIOLOGY
    • ventilation• PaO2 carotid body& respiratory center ventilation PaCO2 Chronic hypoxia Sedative agent Performance During sleep
    • ventilatory acclimatization ventilation pH return to pH (respi alkalosis) normal HCO3 excrete via Acetazolamide kidney
    • • EPO w/in 2 hr• Rbc mass w/in days to wks• if excessive  chronic polycythemia
    • Fluid Balance• Reset Osm stat:  plasma volume and hyperosmolality (s osm290 - 300)• diuresis and hemoconcentration :healthy response• Antidiuresis is a hallmark of AMS Peripheral venous in central ADH diuresis constriction blood volume &aldosterone
    • Cardiovascular System CO = SV HRPulm.vasoconstriction pulm.pressureCerebral blood volume O2 to brain ICP
    • Exercise capacity• measured by VO2max, drops dramatically on ascent to altitude• During acclimatization, submaximal endurance after 10 days
    • Sleep at High Altitude• Sleep stages III and IV ↓ stage I   frequent arousals (improve with time at altitude)• Cheyne-Stokes respiration in those sleeping at >2700 m (>8860 ft)• the frequent awakenings & periodic breathing not related to AMS• mechanism of the lighter sleep →cerebral hypoxia.• Quality of sleep and arterial oxygenation during sleep improve with acclimatization and with acetazolamide
    • HIGH-ALTITUDE SYNDROMES
    • High altitude syndrome• Acute hypoxia• Acute mountain sickness• High-Altitude cerebral edema• High-Altitude pulmonary edema• Peripheral edema• High-altitude retinopathy• High-altitude pharyngitis and bronchitis• Chronic mountain polycythemia• UV keratoconjunctivitis
    • Acute hypoxia• occurs in the setting of sudden and severe• Unacclimatized persons become unconscious at SaO2 50 - 60%, PaO2 < 30 mm Hg, or a jugular venous PO2 of <15 mm Hg• immediate administration of oxygen, rapid descent
    • Acute Mountain Sickness• setting of more gradual and less severe hypoxic• characterized by headache, GI disturbances, dizziness or light-headedness, and sleep disturbance
    • What’re factors determine individual susceptibility to AMS ?• Age• Sex• Body weight• physical fitness
    • Pathophysiology• renin-angiotensin aldosterone ADH The cerebral edema, interstitial pulmonary edema, peripheral edema, and antidiuresis
    • Clinical feature• mild : alcohol hangover• Headaches : bifrontal and worsen with bending over or performing a Valsalva maneuver• GI symptoms : anorexia, N/V• irritable & wants to be left alone• Sleepiness• deep inner chill also are common
    • Clinical feature• rapid ascent of an unacclimatized person to ≥2000 m• Symptoms develop between 1 -6 hours later, but sometimes are delayed for 1 - 2 days Severe Ataxia vomiting oliguria HACE headache and AOC
    • Physical examination• percent SaO2 overall correlates poorly with the diagnosis of AMS• postural hypotension may be present• Localized rales ≥ 20%• Funduscopy :tortuosity and dilatation, and retinal hemorrhages (at altitudes >5000 m)• facial and peripheral edema is a hallmark
    • The goals of treatment are to prevent progression abort the illness improve acclimatization
    • 3 principles of Rx(1) do not proceed to a higher sleeping altitude in the presence of symptoms(2) descend if symptoms do not abate or become worse despite treatment(3) descend and treat immediately in the presence of a change in consciousness, ataxia, or pulmonary edema
    • Treatment• Oxygen effectively relieves symptoms, but it is generally unavailable in the field or reserved for those with moderate to severe AMS
    • MedicationIndications for acetazolamide(1) a history of altitude illness(2) abrupt ascent to >3000 m (>9840 ft)(3) AMS requiring treatment(4) bothersome periodic breathing during sleep
    • Symptomatic treatment of AMS• Headache :aspirin, acetaminophen or ibuprofen• N/V: ondansetron• f/q wakening: zolpidem,diphenhydramine
    • Prevention• Graded ascent with adequate time for acclimatization is the best prevention• Prophylactic acetazolamide – started 24 hr before the ascent – continued for the first 2 days at altitude – restarted if illness develops
    • HACE• HACE : progressive neurologic deterioration in someone with AMS or HAPE• altered mental status, ataxia, stupor, and progression to coma if untreated• severe, diffuse cerebral edema with multiple small hemorrhages and sometimes thrombosis
    • Treatment of HACE• oxygen supplementation• descent(the highest priority)• steroid therapy• acetazolamide may be used as an adjunct
    • MRI findingsreversible white matter edema evidenced byT2 signal, esp.in the splenium of the corpus callosum
    • HAPE• most lethal of the altitude illnesses• easily reversible with descent and oxygen administration• Risk factors:heavy exertion, rapid ascent, cold, excessive salt ingestion, use of a sleeping medication
    • Pathophysiology• HAPE is a noncardiogenic, hydrostatic edema• The culprit in HAPE is high microvascular pressure  Pulmonary hypertension
    • Clinical• Early diagnosis is critical, exercise performance & dry cough are enough to raise the suspicion of early HAPE• The condition typically worsens at night• Low-grade fever is common, and tachycardia and tachypnea• SO2 low for altitude
    • Chest radiographicprogress from interstitial  localized alveolar  generalized alveolar infiltrates
    • Treatment• The key to successful Rx : early recognition, early stage is easily reversible• Immediate descent is the Rx of choice, but this is not always possible• The optimal therapy depends on – the environmental setting, – evacuation options – availability of oxygen or hyperbaric units – ease of descent
    • Portable hyperbaric bag
    • medication• Because oxygen and descent are so effective, experience with drugs has been limited• nifedipine, phosphodiesterase 5 inhibitors:sildenafil and tadalafil
    • Other high altitude medical problem• Peripheral edema• High-altitude retinopathy• High-altitude pharyngitis and bronchitis• UV keratoconjunctivitis
    • Special population• Patients who have hypoxic cardiovascular and pulmonary diseases such as COPD or CHF , CAD, pregnant