Rosen & Barkin's 5-Minute Emergency Medicine Consult (346 page)

• AMS:
  
  • Without presence of HAPE or HACE, the physical exam will often be normal:
    
    • Mild stages of AMS are often misdiagnosed as viral syndromes or hangovers from alcohol ingestions
      
• HAPE:
  
  • Tachypnea
    
  • Rales
    
  • Cyanosis
    
  • Fever may be present.
    
  • Severe respiratory distress and death may occur.
    
• HACE:
  
  • Ataxia
    
  • Papilledema, retinal hemorrhages
    
  • Altered mental status/global encephalopathy:
    
    • Focal neurologic deficit less common
      
    • Seizure (rare)
      
    • Coma
      
    • Has been described as “end-stage” AMS
      

• Clinical diagnosis in the setting of recent altitude gain
  
• AMS:
  
  • Diagnosis made with history of headache + at least 1 of the following:
    
    • Nausea/vomiting
      
    • Lassitude/fatigue
      
    • Dizziness
      
    • Insomnia
      
  • No diagnostic lab or imaging studies
    
• HAPE:
  
  • Dyspnea on exertion—universal finding at altitude
    
  • Dyspnea at rest—symptom of HAPE, worse at night
    
  • Rales, cyanosis, or cough support diagnosis.
    
  • Tachycardia, tachypnea often correlate with severity.
    
• HACE:
  
  • Cerebellar ataxia with or without other symptoms of AMS
    
  • Papilledema, retinal hemorrhages are associated findings.
    

Arterial blood gas (ABG) for HAPE:

• Reveals hypoxemia (pO
  ₂
  30–50) and respiratory alkalosis,
  not
  acidosis
  

• CXR in HAPE:
  
  • Reveals patchy alveolar infiltrates with areas of clearing between patches
    
  • Unilateral or bilateral infiltrates (right mid-lung field being most common)
    
  • Cardiomegaly, “batwing” distribution of infiltrates, and Kerley B lines (typical of cardiogenic pulmonary edema)—are generally absent in HAPE
    
• CT and MRI scans in HACE:
  
  • Vasogenic edema of white matter
    

ECG in HAPE:

• Tachycardia
  
• Evidence of right-heart strain
  

• AMS:
  
  • Alcohol hangover
    
  • Carbon monoxide poisoning
    
  • Encephalitis
    
  • Exhaustion
    
  • Meningitis
    
  • Viral syndrome
    
• HAPE:
  
  • High-altitude bronchitis and pharyngitis
    
  • Pneumonia
    
  • Pulmonary embolism:
    
    • More rapid onset
      
    • Pleuritic chest pain
      
• HACE:
  
  • Cerebrovascular accidents/transient ischemic attacks:
    
    • Focal neurologic signs suggest vascular lesion.
      

TREATMENT

• Severe cases require immediate evacuation to lower altitude.
  
• Do not proceed to higher altitude in the presence of symptoms.
  
• Oxygen delivery or simulated descent in portable hyperbaric chamber (Gamow bag) can be lifesaving temporary measure making self-rescue possible.
  

• HAPE and HACE:
  
  • ABCs:
    
    • Endotracheal intubation for impending respiratory failure or airway protection
      
  • Establish IV access.
    
  • Supplemental oxygen and monitoring
    
  • CPAP for HAPE
    

• AMS:
  
  • Mild cases usually self-limited:
    
    • Symptomatic treatment
      
    • Halt ascent until symptoms resolve
      
  • Acetazolamide for moderate to severe symptoms
    
  • Ibuprofen or acetaminophen for headache
    
  • Promethazine or ondansetron for nausea
    
  • Supplemental oxygen in severe cases
    
  • Descent for severe or persistent symptoms
    
  • Acetazolamide for AMS prophylaxis:
    
    • In high-risk individual with planned rapid ascent
      
• HAPE:
  
  • Immediate descent for moderate/severe symptoms
    
  • Mild cases may be managed without descent if:
    
    • Adequate oxygen supplies available
      
    • Serial medical exam possible
      
    • Immediate descent for any deterioration in clinical status
      
  • Bed rest to avoid exercise-induced pulmonary HTN
    
  • Supplemental oxygen:
    
    • High flow rates (6–8 L/min) until improvement, then continue with lower flow rates
      
  • Nifedipine when other interventions are unavailable
    
  • β-agonist inhalers may be helpful.
    
  • Hyperbaric therapy is available and immediate descent is not possible
    
• HACE:
  
  • Immediate evacuation to lower altitude
    
  • Oxygen
    
  • Dexamethasone
    
  • Bed rest with elevation of head at 30°, and in severe cases, aggressive management of elevated intracranial pressure
    

• Acetazolamide:
  
  • AMS treatment: 250–500 mg (peds: 5 mg/kg) PO BID
    
  • AMS prophylaxis: 250 mg PO BID (peds: 5 mg/kg) PO BID; start 24 hr before ascent
    
• Dexamethasone: 8 mg IV, then 4 mg PO/IV QID
  
• Ibuprofen: 800 mg (peds: 5–10 mg/kg) PO TID
  
• Nifedipine: 10 mg PO, then 30 mg sustained release (SR) PO QD
  
• Promethazine: 12.5–25 mg (peds: 0.25–1 mg/kg) PO/PR (per rectum)/IM q4–6h
  

• Acetazolamide (AMS)
  
• Nifedipine (HAPE)
  

Dexamethasone

The use of multiple medications in treating high-altitude illness is not supported by the current literature

FOLLOW-UP

Descent to a lower altitude mandatory in severe cases

• Persistent symptoms after observation in lower-altitude ED require admission.
  
• HAPE
  
• HACE
  

Once clinical improvement seen and oxygen saturation >95% on room air at sea level or appropriate normal saturation at higher altitudes

Offer prophylactic therapy for future ascents in patients with recurrent AMS (acetazolamide) or HAPE (nifedipine).

• The symptoms of high-altitude illness can resemble mild viral syndromes.
  
• Failure to consider high-altitude illness is a common pitfall.
  
• When managing altitude illness, once symptoms have developed and until they resolve, further ascent is contraindicated.
  
• Ataxia and dyspnea at rest are potentially early indicators of HACE and HAPE, respectively.
  
• Hyperbaric oxygen and adjunctive medications should be considered when descent is not possible.
  

• Basnyat B, Murdoch DR. High altitude illness.
  Lancet.
  2003;361:1967–1974.
  
• Eide RP, Asplund CA. Altitiude illness: Update on prevention and treatment.
  Curr Sports Med Rep.
  2012;11:124–130.
  
• Hackett PH, Roach RC. High-altitude illness.
  N Engl J Med.
  2001;345:107–114.
  
• Jones BE, Stokes S, McKenzie S, et al. Management of high altitude pulmonary edema in the Himalaya: A review of 56 cases presenting at Pheriche medical aid post (4240 m).
  Wilderness Environ Med
  . 2013;24(1):32–36.
  
• Lipman GS, Kanaan NC, Holck PS, et al. Ibuprofen prevents altitude illness: A randomized controlled trial for prevention of altitude illness with nonsteroidal anti-inflammatories.
  Ann Emerg Med.
  2012;59:484–490.
  
• Yaron M, Honigman B. High altitude medicine. In: Marx JA, ed.
  Rosen’s Emergency Medicine: Concepts and Clinical Practice
  . 7th ed. Philadelphia, PA: Mosby; 2010:1917–1928.
  

CODES

993.2 Other and unspecified effects of high altitude

BASICS

• Hip injury includes hip fractures and dislocations of the proximal femur due to minor or major trauma or overuse.
  
• Hip fracture: Fracture of proximal femur. Classified as intracapsular or extracapsular.
  
  • Intracapsular fracture: Femoral head or neck; often associated with disruption of femoral neck vessels; significant morbidity due to AVN:
    
    • Femoral head fracture: Usually associated with hip dislocation (anterior > posterior).
      
    • Femoral neck fracture: Usually older adults with minor trauma, or young patient with major trauma; symptoms vary. Patient may or may not be ambulatory. Often site of stress fracture in runners/military recruits.
      
  • Extracapsular fractures: Below acetabular capsule. Normally do not disrupt blood flow. Morbidity typically due to patient immobilization: DVT, PE:
    
    • Trochanteric fractures: Greater trochanter usuallyfractured by avulsed at insertion in gluteus medius. Lesser trochanter usually fractured by avulsed from forceful contraction of iliopsoas; seen in young athletes and children.
      
    • Intertrochanteric fracture: Defined as occurring in line between greater and lesser trochanters. Common in elderly, osteoporosis patients often due to fall. Marked external rotation and shortening. Can be stable or unstable. Nonambulatory.
      
    • Subtrochanteric fracture: Usually due to direct, significant trauma in younger patients or lesser trauma in elderly. Common site of pathologic fracture. Can be site of significant blood loss and shock.
      
• Hip dislocation: Disarticulation of femoral head. Classified as posterior, anterior, and central:
  
  • Posterior dislocation (most common):
    
    • Often from motor vehicle accident (MVA) in which knees strike dashboard
      
    • 10% associated with sciatic nerve injury
      
  • Anterior dislocation: 10% hip dislocations:
    
    • Often due to trauma with sudden abduction of thigh
      
    • Associated femoral head fractures, femoral nerve injury
      
    • Can be anterior superior, or anterior inferior
      
  • Central dislocation with acetabular fracture:
    
    • Usually from direct impact to greater trochanter
      
    • Associated significant blood loss, sciatic nerve injury