High Altitude Problems And Dysbarism

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High Altitude Problems And Dysbarism

• Dr Oredein

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Preamble

• General Characteristics
• Incidence depends on
• Rate of ascent
• Final altitude
• Sleeping altitude
• Duration at altitude
• Individual susceptibility

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Acute Mountain Sickness

• Incidence
• 67 with rapid ascent
• 20 for skiers visiting resorts
• 15-20 with ascent to 8,5009000ft in one day

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Acute Mountain Sickness

• Clinical Manifestations
• Generally benign and self-limited
• Onset 4-12hrs after ascent
• Headache, fatigue, dizziness, weakness
• Anorexia/ nausea/ vomiting
• Lightheadedness
• Difficulty sleeping due to periodic breathing
• Ataxia

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Acute Mountain Sickness

• ? ?
• Viral syndrome
• Exhaustion
• Alcohol hangover
• CO poisoning

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Acute Mountain Sickness

• Treatment
• Mild cases
• Self-limited
• Symptomatic treatment
• Halt ascent till symptoms resolve
• Acetazolamide
• For prevention and treatment
• 250mg BD starting 24hrs prior to ascent

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Acute Mountain Sickness

• Aspirin/ acetaminophen
• Prochlorperazine
• Dexamethazone
• Supplemental oxygen
• Descent for severe or persistent symptoms
• Simulated descent with GMT

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Acute Mountain Sickness
                                               
        
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Acute Mountain Sickness

• Prevention
• Graded Ascent
• Avoid increase in sleeping greater than 2,000ft
  when over 8,000

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High Altitude Pulmonary Edema

• Incidence
• lt 1-2
• Affects 0.01 of skiers in Colorado/yr
• Affects 1in 50climbers of Mt. McKinley
• Varies with rate of ascent

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High Altitude Pulmonary Edema

• Pathophysiology
• Non-cardiogenic PE
• Precise pathophysiology is unknown
• Combination of alveolar leakage with
  overperfusion
• Impaired endothelial/epithelial barrier
• Intense pulmonary artery vasoconstriction

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High Altitude Pulmonary Edema

• Clinical Presentation
• Occurs 2-4 days after ascent
• Fatigue / weakness
• Cough / dyspnea at rest / tachypnea
• Rales
• Cyanosis
• Severe respiratory distress and death

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High Altitude Pulmonary Edema

• ? ?
• Pneumonia
• High altitude bronchitis and pharyngitis
• PE

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High Altitude Pulmonary Edema

• CXR findings
• Patchy infiltrates with areas of clearing between
  the patches
• Unilateral or bilateral
• Cardiomegaly, bat-wing distribution of
  infiltrates and kerley-B lines are absent

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HAPE
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High Altitude Pulmonary Edema

• Treatment
• ABCs
• Supplemental O2
• Descent
• Bed rest
• Nifedipine
• Lasix, morphine, acetazolamide

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High-Altitude Cerebral Edema

• Incidence
• lt 1
• Life-threatening
• Occurs in the presence of HAPE
• Rarely seen as an isolated entity

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High-Altitude Cerebral Edema

• Clinical Manifestations
• Develops within 3-4 days
• May occur 12hrs after the onset of AMS
• Nausea / vomiting
• Severe headache
• Ataxia / focal neurological deficit / seizures
• Altered mental status
• Coma

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High-Altitude Cerebral Edema

• ? ?
• TIA
• CVA

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High-Altitude Cerebral Edema

• Treatment
• ABCs
• Immediate evacuation to lower altitude
• O2
• Dexamethazone
• Bed rest

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High-Altitude Retina Hemmorhage

• Common at altitude gt 17,500
• Incidence unknown
• Related to strenuous exercise at high altitude
• Noted commonly in presence of severe HACE or HAPE
• Usually self limited and resolve within 2-3wks

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HARH
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Dysbarisms

• Dysbarisms are illnesses that result directly or
  indirectly from exposure to increased ambient
  pressure.

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Decompression Sickness

• Gas Laws
• Henrys Law
• Daltons Law
• Boyles Law

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Decompression Sickness

• Mechanism
• ? ambient pressure? pN inspired
• N accumulates in tissues in higher concentration
  the longer the pressure remains high
• DCS results when pressure keeping the N in
  solution ? too rapidly on ascent ? bubble
  formation

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Decompression Sickness

• Risk Factors for DCS
• Greater depth, longer bottom timeand quicker rate
  of ascent
• ? age, ? weight (body fat),
• Hypothermia
• Dehydration, exercise, multiple dives in a day
• Lower cabin pressure

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Decompression Sickness

• Clinical Manifestations
• Time after surfacing to presentation of DCS
• 50- symptoms within 1hr
• 95- symptoms within 12hrs
• 60 of neurologic DCS within 10minutes

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Decompression Sickness

• Clinical Manifestations
• Cutaneous
• Scarlatiniform, erisipeloid or mottled rash
• Peau dorange appearance
• Musculoskeletal (no external physical signs)
• Pain
• Classic bends
• Dull deep aching ( joints- elbow and shoulder
• Not exacerbated by movement or reproduced with
  palpation

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Decompression Sickness

• Pulmonary
• Dyspnea
• chokes
• Substernal pressure
• Cough
• Dyspnea
• GI
• Nausea / vomiting
• Abdominal pain

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Decompression Sickness

• CNS
• Weakness / fatigue / lethargy
• Numbness / paraesthesia
• Agitation
• Headache
• Dizziness, vertigo, visual disturbance
• Convulsion
• Bowel/bladder incontinence
• Staggers

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Decompression Sickness

• Treatment
• ABCs
• ETT
• Early recompression in hyperbaric chamber
• For all DCS
• Tranportation to nearest hyperbaric facility
• Chest tube

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Decompression Sickness

• IV Rehydration with 0.9NS
• Water Recompression
• Divers Alert Network [phone]

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Barotrauma

• General
• Injury to the body as a result of expansion and
  contraction of gas in an enclosed space
• Boyles Law
• PVK
• Gas filled cavities
• Sinus
• Middle ear
• Lung

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Barotrauma

• Clinical Manifestations
• Middle ear
• Most common type of barotrauma
• Barotrauma of descent
• 10 Vs 30 incidences
• Eustachian tube patency

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Barotrauma

• Begins as a clogged sensation
• ? pain with pressure differential across TM ?
• rupture of TM.
• TM appearance TM congestion ? TM edema ?
• Gross hemmorhage ? TM rupture

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Barotrauma

• Treatment
• Decongestants
• Antihistamine for allergic component
• Antibiotic for TM rupture
• Prevention with decongestant prior to dive

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Barotrauma

• Inner Ear
• Barotrauma of descent
• ?middle ear pressure ? ?ICP ? rupture of round
  or labyrinth windows
• Sudden severe vertigo, disorientation, tinnitus,
  nystagmus, sensorineural hearing loss
• Rx
• Bed rest, avoid straining, surgical repair

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Barotrauma

• Paranasal sinuses
• Barotrauma of descent
• Failed pressure equalization by ostia ?
  congestion, edema and hemmorhage
• Sinus congestion, pain, epistaxis
• RX
• Decongestant
• Antibiotics for severe cases

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Barotrauma

• Gastrointestinal (aerogastralgia)
• Barotrauma of ascent
• Swallowed air expand with ? external pressure
• Excessive belching
• Flatulence
• Abdominal distension

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Barotrauma

• Pulmonary
• Occurs with ascent
• ? risk with COPD, asthma
• Lungs expand against closed glottis
• Can cause arterial gas embolism

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Barotrauma

• Signs/symptoms
• Dyspnea
• Cough with frothy red sputum
• Subcutaneous emphysema
• Delayed symptoms- bull neck appearance,
  dysphagia, changes in voice character
• Treatment
• 100 O2 for ill patients
• ?Intubation
• Needle thoracostomy for tension pneumothorax

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Barotrauma

• Others
• Barodontalgia
• External objects
• Dive suit / mask

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Arterial Gas Embolism

• General Xteristics
• Extreme manifestation of pulmonary barotrauma
• 2nd leading cause of dive-related death
• Overpressurization of lung tissue ? pleural tear
• ? air entering vascular circulation

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Arterial Gas Embolism

• Etiology
• Breathholding during ascent
• Pulmonary AV shunts or paradoxical embolism via a
  patent foramen ovale
• Iatrogenic
• Penetrating wounds

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Arterial Gas Embolism

• Clinical Manifestations
• Cerebral
• Stroke (dive-related)
• Any combination of neurologic deficit
• Apnea and full C-P arrest
• Altered/loss of consciousness 40
• Sensory loss/ motor deficit 20
• Paraplegia 10, seizures 4
• Visual changes, aphasia, paraesthesia

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Arterial Gas Embolism

• Pulmonary
• SOB
• Bloody, frothy sputum
• Subcutaneous air
• Cardiac
• MI
• ? CO
• Hammans sign
• Renal
• Renal infarction

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Arterial Gas Embolism

• Treatment
• Initial stabilization
• ABCs
• 100 oxygen by tight fitting mask
• Intubation
• IV access
• Hyperbaric Oxygen Recompression Therapy
• For all CAGE
• Tredenlenburg position

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KEY CONCEPTS The protective physiologic
response to a decrease in PaO2 at high altitude
is an increase in ventilation known as the
hypoxic ventilatory response (HVR). Patients with
a low HVR, which is mediated by the carotid
bodies, may be at higher risk for acute mountain
sickness (AMS). Acetazolamide, which is a
carbonic anhydrase inhibitor that induces a
bicarbonate diuresis, accelerates natural
acclimatization to high altitude. The symptoms
of AMS can resemble a viral syndrome, and include
headache, nausea, anorexia, fatigue, and
insomnia. High-altitude pulmonary edema is a
noncardiogenic form of pulmonary edema that is
best treated by descent and oxygen. Cerebellar
ataxia is the most important sign indicating that
AMS has progressed to high-altitude cerebral
edema.