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Hyperventilation

Introduction:

  • Hyperventilation is an abnormal increase in the volume of air breathed in and out of the lungs [Figure 1]
  • Results in a result of a significant decrease of carbon dioxide (CO2) content in the blood
  • The symptoms of hyperventilation subside within a few minutes after the rate and depth of breathing are consciously brought back under control
Hyperventilation
Figure 1: Encyclopedia Britannica, Hyperventilation

Possible Causes of Hyperventilation:

  • Stress
  • Panic
  • Anxiety
  • Hypoxia
  • Decreased carbon dioxide in blood
  • Under conditions of stress and anxiety, a person's body reacts automatically to such stimuli whether the danger be imaginary or real
  • One of these automatic reactions is a marked increase in breathing rate which results in a significant decrease in the carbon dioxide content of the blood which is necessary to automatically regulate the breathing process

Hyperventilation Symptoms:

  • As hyperventilation “blows off” excessive carbon dioxide from the body, a pilot can experience symptoms of
  • Lightheadness
  • Nausea
  • Suffocation
  • Drowsiness
  • Tingling in the extremities
  • Coolness
  • Dry mouth
  • Blurred vision
  • Rapid pulse and breathing rate

  • Early symptoms of hyperventilation are similar to those of hypoxia and some to ordinary airsickness
  • Symptoms are not unique and several can occur at the same time
    • Therefore, if a pilot is using an oxygen system when symptoms are experienced, the oxygen regulator should immediately be set to deliver 100% oxygen and the system checked to assure that it has been functioning effectively before giving attention to rate and depth of breathing
  • Symptoms can easily cause confusion and panic which only aggravates the problem by further increasing anxiety, and thus the breathing rate

Effects of Hyperventilation:

  • First and foremost, hyperventilation can be a significant distraction to the safe operation of the aircraft
  • Incapacitation can eventually result from lack of coordination, disorientation, and painful muscle spasms
    • Eventually, unconsciousness can occur

Recovering from Hyperventilation:

  • The symptoms of hyperventilation subside within a few minutes after the rate and depth of breathing are consciously brought back under control
  • The buildup of carbon dioxide in the body can be hastened by talking loudly, or controlled breathing in and out of a paper bag held over the nose and mouth
    • This method does not force you to breathe carbon dioxide but rather forces you to think about your breathing rate
      • This method is not recommended unless absolutely necessary as it may increase carbon dioxide levels too quickly
    • Recovery will occur within a few minutes
  • Remove cause of stress, panic, or anxiety, as able
    • If the source is an emergency which must be dealt with immediately, take a moment and remember your emergency procedure training
  • If incapacitation occurs then the body will naturally recover from the situation and slow the breathing rate

Case Studies:

  • NTSB Identification: ATL90LA025 The National Transportation Safety Board determines the probable cause(s) of this accident to be: Pilot's temporary physical condition (possible hyperventilation or anxiety attack). Soft terrain in the emergency landing was considered to be a related factor
  • NTSB Identification: DEN82DA125 The National Transportation Safety Board determines the probable cause(s) of this accident to be: Physical impairment (other organic problem of the pilot in command
  • NTSB Identification: MIA78DLA01 The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot in command's misjudgment of distance and speed and physical impairment from hyperventilation

Practical Test Standards/Airman Certification Standards:

Conclusion:

  • Hyperventilation is simply a matter of breathing too rapidly
  • It is seldom completely incapacitating but it does produce one or more of the symptoms that are disturbing if not alarming to the uninformed pilot
  • It can look just like hypoxia depending on the symptoms displayed which has been linked to numerous fatal accidents
  • Understand the symptoms and how you will recognize them in yourself and your passengers, along with the appropriate recovery method

References: