Hyperventilation syndrome

• Overview:

  • Ventilation exceeds metabolic demands, leading to haemodynamic and chemical changes producing characteristic symptoms
  • Usually in a young, otherwise healthy patient
  • Relatively common presentation which may be mistaken for panic disorder
• Aetiology:

  • Unknown
  • Certain stressors provoke an exaggerated respiratory response in some individuals - sometimes emotionally stressful events
  • Tend to use accessory muscles to breath, rather than the diaphragm, resulting in hyperinflated lungs and perceived effort or dyspnoea
  • Leads to anxiety and triggers further deep breathing
• Epidemiology:

  • More common in females
  • Usually presents between 15-55 years
• Symptoms:

  • Chest pain - atypical of cardiac origin
  • Respiratory - hyperpnoea, tachypnoea, dyspnoea, wheeze (bronchospasm due to low CO2)
  • CNS (due to reduced cerebral flow secondary to hypocapnia)- dizziness, weakness, confusion, agitation, paraesthesia
  • GI - bloating, epigastric pressure (aerophagia)
  • Metabolic - muscle twitching with positive Chvostek and Trousseau signs, generalised weakness
• Metabolic changes:

  • Electrolyte disturbance secondary to respiratory alkalosis
  • Acute hypocalcaemia - carpopedal spasm, muscle twitching , prolonged QT interval
  • Hypokalaemia
  • Acute hypophosphatemia
• Signs on exam:

  • ECG - prolonged QT and T wave inversion (electrolyte imbalances)
  • ABG - low CO2 and bicarbonate - respiratory alkalosis
  • Positive Chvostek and Trousseau signs - acute hypocalcaemia
• Differential diagnosis:

  • Diagnosis of exclusion
  • Unless a clear history of HVS, any first presentation of hyperventilation should be referred for exclusion of serious underlying pathology
  • Respiratory - ARDS, asthma, pleural effusion, pneumonia, pneumothorax, PE, CO poisoning, COPD
  • Cardiac - AF/flutter, cardiomyopathy, ACS
  • DKA
  • Hyperthyroidism
  • Panic or other anxiety disorders
• Investigations:

  • Unless clear history of HVS, must exclude underlying serious pathology
  • Baseline bloods + TFTs, glucose, calcium, phosphate
  • Pulse oximetry
  • ABG
  • D-dimer
  • ECG
  • CXR
• Acute management:

  • If serious pathology excluded
  • Reassuring the patient
  • Alleviating severe anxiety e.g. use of benzodiazepines
  • Establishment of normal breathing pattern
  • Use of rebreathing into paper bag is no longer recommended due to reports of hypoxia and death
• Further management:

  • Education - relaxation and breathing techniques
  • Formal breathing retraining by physiotherapists
  • Beta blockers and benzodiazepines may be of some use
  • Address any potential co-existing psychiatric issues e.g. depression and anxiety
• Panic disorder = without warning

  Hyperventilation syndrome can happen in response to strong emotions (sometimes happen randomly)