High altitude illness

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High altitude illness

  1. 1. HIGH-ALTITUDE MEDICAL PROBLEMS Priya Kantanon review from tintinelli ed7
  2. 2. High altitude is a hypoxic environment [>2440 m (>8000 ft)]
  3. 3. •Intermediate altitude, 1520 to 2440 m (5000 to 8000ft) Exercise performance Increased alveolar ventilation without major impairment in arterial oxygen transport •Acute mountain sickness (AMS) occurs at and above 2130 to 2440 m (7000 to 8000 ft) and sometimes at lower altitudes in particularly susceptible individuals.
  4. 4. •High altitude, 2440 to 4270 m (8000 to 14,000 ft) decreased arterial oxygen saturation (SaO2) marked hypoxemia may occur during exercise and sleep •Very high altitude, 4270 to 5490 m (14,000 to 18,000 ft) visitors to the mountainous regions of South America and the Himalayas •Extreme altitude, >5490 m (>18,000 ft) complete acclimatization generally is not possible accompanied by severe hypoxemia and hypocapnia.
  5. 5. PHYSIOLOGY OF ALTITUDE ACCLIMATIZATION • Ventilation • Blood • Fluid Balance • Cardiovascular System • Exercise Capacity • Limitations to Acclimatization • Sleep at High Altitude?
  6. 6. VENTILATORY ACCLIMATIZATION • After 4 to 7 days • Primary initial adaptation is maintenance of alveolar PO2 through increased ventilation • Respiratory depressants or stimulants
  7. 7. Hypoxia Hyperventilation Respiratory alkalosis Renal excretion of HCO3 Central chemoreceptors reset to progressively lower PaCO2 pH returns normal ventilation continues to increase Acetazolamide
  8. 8. BLOOD •Erythropoietin level increases (2hrs) •Increased red cell mass over days to weeks •Shifts in the oxyhemoglobin dissociation curve are thought to be minimal 2,3-diphosphoglyceric acid --> right Respiratory alkalosis --> left
  9. 9. Peripheral venous constriction increase in central blood volume baroreceptors decreaseADH& aldosterone diuresis decreased plasma volume and hyperosmolality FLUID BALANCE Antidiuresis is a hallmark of AMS.
  10. 10. CARDIOVASCULAR SYSTEM • SV HR. • BP • Pulmonary circulation constrict • pulmonary pressure • CBF. O2 delivery to brain • ICP
  11. 11. EXERCISE CAPACITY • Drops dramatically • 10% for each 1000-m (3280-ft) altitude gain above 1500 m (4920 ft)
  12. 12. SLEEP AT HIGH ATTITUDE • Sleep stages III and IV are reduced at altitude, whereas sleep stage I is increased
  13. 13. ABNORMAL SLEEP • Increase in arousals • Only slightly less rapid eye movement time • Cheyne-Stokes respiration • Intervals of apnea of >20 seconds Quality of sleep and arterial oxygenation during sleep improve with acclimatization and with acetazolamide.
  14. 14. HIGH-ALTITUDE SYNDROMES • Acute hypoxia • AMS • Pulmonary edema • Cerebral edema • Retinopathy • Peripheral edema • Sleeping problems All fundamental mechanism All same setting of rapid ascent in unacclimatized persons All same essential therapy: descent and oxygen administration.
  15. 15. ACUTE HYPOXIA
  16. 16. S&S • Dizziness • Light-headedness • Dimmed vision • Loss of consciousness Treatment • Oxygen, rapid descent, and correction of the underlying cause
  17. 17. AMS ACUTE MOUNTAIN SICKNESS • More gradual and less severe hypoxic insult than in acute hypoxia syndrome • Headache • GI disturbances • Dizziness or light-headedness • Sleep disturbance
  18. 18. Factors Rate of ascent Sleeping altitude Inherent factors Obesity Not correlate : age,sex,physical fitness
  19. 19. Clinical Features • 1 and 6 hours later, but sometimes are delayed for 1 or 2 days • Especially after a night's sleep • Mild AMS similar to alcohol hangover • Headaches, GI symptoms , constitutional symptoms • Irritable and often wants to be left alone
  20. 20. • SaO2 is typically normal for a given altitude Correlates poorly with the diagnosis of AMS • Duration : 15-94hr at 3000m • At higher sleeping altitudes : • May last much longer, up to weeks if untreated • More likely to progress to pulmonary or cerebral edema
  21. 21. Differential diagnosis • Hypothermia • Carbon monoxide poisoning • Pulmonary or CNS infection • Dehydration • Migraine • Exhaustion
  22. 22. Treatment • Descent and Oxygen • The three principles of treatment are 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.
  23. 23. Treatment Oxygen supplementation • Promptly relieves headache, dizziness, and most other symptoms, although ataxia may resolve more slowly • Nocturnal administration of low-flow oxygen (0.5 to 1 L/min)
  24. 24. MedicalTherapy Acetazolamide • Carbonic anhydrase inhibitor • Should be avoided by individuals with a history of anaphylaxis to sulfa antibiotics • Alters the flavor of beer and other drinks
  25. 25. Indications for acetazolamide 1) History of altitude illness 2) Abrupt ascent to >3000 m (>9840 ft) 3) AMS requiring treatment 4) Bothersome periodic breathing during sleep. 5 mg/kg/d PO in two or three divided doses is sufficient for prevention or treatment 125 mg PO twice daily is effective for prevention
  26. 26. Symptomatic treatment Headache • Aspirin is effective for prophylaxis Nausea and vomiting • Ondansetron orally disintegrating tablets, 4 to 8 mg every 4 to 6 hours Frequent wakening • Short-acting benzodiazepine • Newer nonbenzodiazepine • Diphenhydramine 25 to 50 mg
  27. 27. Prevention • Graded ascent with adequate time for acclimatization • Spend a night at an intermediate altitude of 1500 to 2000 m, before sleeping at altitudes >2500 m • Avoiding overexertion, alcohol, and respiratory depressants • Acetazolamide : started 24 hours before the ascent and should be continued for the first 2 days at altitude. • Dexamethasone, 4 milligrams PO every 12 hours, starting the day of ascent and continuing for the first 2 days at altitude.
  28. 28. High altitude Cerebral edema
 HACE • Altered mental status, ataxia, stupor, and progression to coma if untreated. • Headache, nausea, and vomiting are not always present. • Because of raised ICP, focal neurologic signs, such as third and sixth cranial nerve palsies, may result. HACE = progressive neurologic deterioration in someone with AMS or HAPE
  29. 29. Treatment • Descent is the highest priority. • Oxygen supplementation, descent, and steroid therapy. • In acutely ill patients who cannot descend, of steroids, supplemental oxygen, and a hyperbaric bag • Acetazolamide may be used as an adjunct
  30. 30. • Ataxic or confused after descent should be admitted to hospital. • Coma may persist for days, even for weeks, after evacuation to lower altitude, yet the patient may still recover.
  31. 31. • reversible white matter edema
  32. 32. 
 High altitude pulmonary edema HAPE • Most lethal of the altitude illnesses • Risk factors • Heavy exertion • Rapid ascent • Cold • Excessive salt ingestion • Use of a sleeping medication • Previous history indicating inherent individual susceptibility Pulmonary hypertension • Intracardiac shunts (atrial septal defect • Patent ductus arteriosus (patent foramen ovale) • Drug-induced pulmonary hypertension (phentermine) • Chronic venous thrombotic disease.
  33. 33. PATHOPHYSIOLOGY • High microvascular pressure • Venous constriction and Uneven arterial vasoconstriction overperfusion of some areas of the lung vasculature Noncardiogenic pulmonary edema
  34. 34. CLINICAL FEATURES • Dry cough • Decreased exercise performance • Dyspnea on exertion • Increased recovery time from exercise • Localized rales, usually in the right mid-lung field • Late : tachycardia, tachypnea, dyspnea at rest, marked weakness, productive cough, cyanosis, and more generalized rales develop, altered mental status and eventually coma develop Decreased exercise performance and Dry cough are enough to raise the suspicion of early HAPE
  35. 35. CLINICALS • Strong and fit • May or may not have symptoms of AMS before • Second night at a new altitude • Sign of acute pulmonary hypertension
  36. 36. TERATMENT • Early recognition!!! • Exertion by the patient must be minimized • Oxygen supplementation • Bed rest, keep warm • CPAP, Bi-PAP Immediate descent is the treatment of choice
  37. 37. MEDICATION. (WHEN OXYGEN IS UNAVAILABLE) • Nifedipine (10) , (30) for treatment • Nifedipine SL(20)1 tab q 8hr for prophylaxis • Nitric oxide • Phosphodiesterase 5 inhibitors, sildenafil and tadalafil blunt hypoxic pulmonary vasoconstriction • Tadalafil(10) 1x2 ,24 hours prior to ascent • Inhaled salmeterol bid None of these agents is as effective as oxygen administration or descent, which still remain the treatments of choice
  38. 38. • Hospitalization • Adequate discharge criteria progressive clinical and radiographic improvement PaO2 of 60 mm Hg or SaO2 of >90% • An episode of HAPE is not a contraindication to subsequent ascent
  39. 39. PERIPHERAL EDEMA • Face and distal extremities • 18% of trekkers at 4200 m (13,800 ft) in Nepal • Twice as common in women • Often was associated with AMS but not in all cases • Thorough examination for pulmonary and cerebral edema
  40. 40. HIGH-ALTITUDE RETINOPATHY • Retinal edema, tortuosity and dilatation of retinal veins, disc hyperemia, retinal hemorrhage, and, rarely, cotton-wool exudates. Retinal hemorrhages • Macular hemorrhages • Resolve spontaneously in 10 to 14 days. • Hemorrhages are common at sleeping altitudes of >5000 m (>16,400 ft)
  41. 41. HIGH-ALTITUDE PHARYNGITIS AND BRONCHITIS • Dry, hacking cough. • Purulent bronchitis and a painful pharyngitis • Not infection • Bronchospasm • Severe coughing spasms --> cough fracture of the ribs
  42. 42. • Fast-acting agonists, such as albuterol, MDI relief coughing spasms • Prophylactic use of long-acting agonists and inhaled steroids
  43. 43. ULTRAVIOLET KERATITIS (SNOW BLINDNESS) • UVA and UVB • Less cloud cover, less water vapor, and less particulate matter in the air • Radiation increases roughly 5% for every 300 m (9800 ft) gained and is exacerbated by reflection back from snow
  44. 44. SYMPTOMS • May not become apparent for 6 to 12 hours. • Severe pain, a foreign-body or gritty sensation, photophobia, tearing, marked conjunctival erythema, chemosis, and eyelid swelling TREATMENT • UV keratitis generally is self-limited and heals within 24 hour • Systemic analgesics. , cold compresses with eye patches
  45. 45. SUNGLASSES • should transmit <10% of UVB light. • Side shields and polarizing lenses • "Eskimo sunglasses"
  46. 46. CHRONIC MOUNTAIN POLYCYTHEMIA/CHRONIC MOUNTAIN SICKNESS • Monge disease • Excessive polycythemia • Phlebotomy, relocation to a lower altitude, or home oxygen use
  47. 47. INDIVIDUALS WITH ILLNESSES AGGRAVATED BY HIGH ALTITUDE • Chronic lung disease • Atherosclerotic heart disease • Sickle cell disease • Pregnant Women
  48. 48. EXPOSURETO HIGH ALTITUDE RECOMENDATION
  49. 49. !ank y"
  50. 50. DESCENT AND OXYGEN!!!
  51. 51. AMS HACE HAPE S&S Headache GI disturbances Dizziness or light-headedness Sleep disturbance progressive neurologic deterioration in someone with AMS or HAPE decrease exercise performance,Dry cough,DOE acute PHTN risk factor Rate of ascent Sleeping altitude Inherent factors Obesity not known Heavy exertion,Rapid ascent,Cold, Excessive salt ingestion,Use of a sleeping medication,Previous history indicating inherent individual susceptibility,PulHTN prevention Acetazolamide,Dexa,grad ual ascend none gradual ascend,tadalafil,nifedipine,ac etazolamide treatment oxygen & descend Acetazolamide,dexa hyperbaric bag,dexa Nifedipine,NTG,tadalafil,rest, hyperbaric bag HIGH-ALTITUDE ILLNESS

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