Rosen & Barkin's 5-Minute Emergency Medicine Consult (190 page)

• Conjunctivitis
  
• Hordeolum and Chalazion
  
• Periorbital and Orbital Cellulitis
  
• Red Eye
  

CODES

BASICS

Multisystemic disease process resulting from escape of inert gas bubbles (nitrogen) out of solution into body fluids and tissues

Mechanism:

• Pathophysiology:
  
  • Increases in ambient pressure cause increase in partial pressure of nitrogen inspired (as per Henry law, below).
    
  • Nitrogen accumulates in tissues in increasing concentrations the longer ambient pressures remain elevated.
    
  • Decompression sickness (DCS) results when ambient pressure keeping nitrogen in solution decreases too rapidly (on ascent), preventing gradual removal of excess body burden of nitrogen.
    
  • As the nitrogen removal gradient is overwhelmed, tissues become supersaturated and bubble formation occurs.
    
• Henry law:
  
  • Amount of gas that will dissolve in a solution at a given temperature is directly proportional to partial pressure of that gas.
    
  • Increases in partial pressure result in larger amount of gas dissolved in tissue.
    
  • Decreases in partial pressure result in gas coming out of solution.
    
• Bubbles are viewed as foreign material by body inciting inflammatory and coagulation responses
  
  • Leads to increased vascular permeability and decreased intravascular volume and hemoconcentration
    
• Bubble location determines clinical effects:
  
  • Blood flow and lymphatic obstruction leading to ischemia, infarction, or lymphedema
    
  • Mechanical distention of tissues leading to pain
    
• Risk factors for DCS:
  
  • Dive factors:
    
    • Greater depth
      
    • Longer bottom time
      
    • Multiple dives in a day
      
    • Rapid ascent
      
    • Cold water
      
  • Human factors:
    
    • Obesity
      
    • Intercurrent illness
      
    • Pulmonary disease
      
    • Dehydration
      
  • Proper use of dive tables and computers does
    not
    eliminate risk for DCS.
    
  • Predive vigorous exercise may reduce risk
    
• 50% of patients develop symptoms in 1 hr, 90% develop symptoms within 6 hr.
  
• Airplane flight following diving can precipitate DCS owing to lower cabin pressure.
  

DIAGNOSIS

• Cutaneous:
  
  • Scarlatiniform, erysipeloid, or mottled rash:
    
    • Mottling (
      Cutis marmorata
      ) often indicates more severe disease
      
  • Peau d’orange appearance owing to lymphatic obstruction
    
• Musculoskeletal (the bends):
  
  • Pain:
    
    • Dull, deep muscular aching
      
    • Often in a joint (elbow and shoulder most common)
      
    • Typically not exacerbated by movement or reproduced with palpation
      
• GI:
  
  • Nausea and vomiting
    
  • Abdominal pain
    
• Pulmonary (the chokes):
  
  • Pulmonary vasculature obstruction from bubble burden (venous gas embolism)
    
  • Acute respiratory distress
    
    • Substernal chest pain/pressure
      
    • Cough
      
    • Dyspnea
      
    • Hypoxia
      
• CNS:
  
  • Weakness and fatigue
    
  • Numbness and paresthesia
    
  • Agitation
    
  • Headache
    
  • Dizziness
    
  • Vertigo
    
  • Convulsion
    
  • Bladder and/or bowel incontinence
    
  • Lethargy
    
  • Visual disturbances
    
  • Most commonly affects spinal cord (lower thoracic and lumbar regions)
    
• Inner ear (the staggers):
  
  • Vestibular damage
    
  • Dizziness, vertigo, tinnitus, nausea
    
  • Similar symptoms to inner ear barotrauma but with worse prognosis
    

Meticulous dive history including time at depth, ascent history, and onset of symptoms.

Thorough physical exam including a detailed neurologic exam

• Clinical diagnosis: Recognize risk factors and various clinical presentations.
  
• Careful neurologic exam to document possible waning symptoms
  
• Trial of pressure:
  
  • Rapid relief of symptoms upon recompression in a hyperbaric chamber may be the only way to diagnose DCS conclusively.
    

• CBC:
  
  • Increased hematocrit secondary to hemoconcentration
    
• Electrolytes, BUN, creatinine, glucose
  
• Urinalysis
  
  • Increased specific gravity may indicate intravascular volume depletion
    
• ABG and pulse oximetry:
  
  • Monitor oxygenation
    

• CXR:
  
  • Concomitant pulmonary barotrauma
    
  • Noncardiogenic pulmonary edema from DCS
    
• Extremity x-ray
  
  • Rule out trauma as cause of pain
    
• Head CT when altered mental status or neurologic deficit
  

• Musculoskeletal injury unrelated to bubble formation
  
• Inner or middle ear barotraumas
  
• Arterial gas embolism
  
• Cerebrovascular accident (CVA)
  
• Trauma
  

TREATMENT

• Cautions:
  
  • Recognize DCS:
    
    • Postdive extremity pain often attributed to muscle strain
      
    • Serious neurologic complaints often minimized because diver does not consider DCS
      
  • If air evacuation required:
    
    • Limit altitude to less than 1,000 ft or use pressurized aircraft
      
• Controversies:
  
  • In-water recompression:
    
    • Return injured diver/patient to depth where symptoms are ameliorated.
      
    • Extremely difficult
      
    • Need large amount of surface support
      

• Airway, breathing, and circulation management (ABCs)
  
• Provide normobaric (100%) oxygen via mask or endotracheal tube (ETT):
  
  • Increases inert gas (nitrogen) elimination from tissues, reducing gas bubble size
    
  • Increases oxygen delivery to injured tissue
    
• Maintain patient in supine position to prevent further cerebral involvement
  
• Early recompression in hyperbaric chamber
  

• IV rehydration with 0.9% normal saline (NS) to maintain goal urine output of 1–2 mL/kg/h:
  
  • Diver usually dehydrated owing to diuretic effect of pressure, exercise, breathing dry compressed air, and increased vascular permeability
    
  • Increased fluid assists with gas removal and dissolution of nitrogen
    
• Hyperbaric oxygen recompression therapy (see Hyperbaric Oxygen Therapy):
  
  • Arrange transportation to nearest hyperbaric facility.
    
  • Prophylactic chest tube for simple pneumothorax to prevent conversion to tension pneumothorax in chamber
    
  • Fill endotracheal and Foley catheter balloons with water or saline to avoid shrinkage/damage during recompression.
    
  • Recompression therapy protocols found in US Navy diving manual
    
• Divers Alert Network (DAN):
  
  • Provides 24-hr emergency hotline for medical consultation on treatment of dive-related injuries and for referrals to hyperbaric chambers ([919] 684-9111)
    
• Analgesics and antiemetics
  
• Diazepam (Valium) for severe vertigo
  
• Adjunctive therapy with NSAIDs and/or heliox may reduce number of recompression treatments required
  

FOLLOW-UP