DB

• during inspiration, the diaphragm flattens to increase thoracic cavity
• Normal Breathing

  • Usually via nose
  • Diaphragm 70 - 80% inspiratory work
  • Expiration passive
  • I:E ratio 1:2
  • Quiet and relaxed
  • Regular
  • 12 - 15 bpm
  • VT 500 mls

  
• Dysfunctional Breathing:

  • DB is a psychologically (primary) or physiologically (secondary) based respiratory disorder
  • Characterised by abnormal breathing pattern with patients presenting with
  • erratic breathing
  • episodic breath holding and sighing
  • apical breathing pattern - upper chest movement due to accessory muscle use
  • breathing too deeply or too rapidly (hyperventilation)
• Hyperventilation:

  • Hyperventilation is breathing in excess of metabolic requirements
  • ‘Flight or fight’ response
  • Causes a decrease in PaCO2 from normal range of 4.5 to 6 kpa
  • Acute hyperventilation may be triggered by a number of factors
  • Hyperventilation syndrome (HVS) – chronic and habitual hyperventilation
• Possible Aetiology of Dysfunctional Breathing/HVS:

  • Type A personality
  • Respiratory disease
  • Drugs
  • Psychiatric disease
  • Psychological problems
  • Pain
  • Physiological issues
  • Organic disorder
• CO2 Theory

  • Breathing in excess of the body’s metabolic requirement -> low CO2 (hypocapnia)
  • Sustained hypocapnia -> respiratory alkalosis
  • Respiratory alkalosis associated with range of symptoms
  • Chemoreceptors “re-set” to trigger at lower levels of CO2 perpetuating problem of over breathing (hyperventilation)
  • Not all patients with DB hyperventilate
• Effects of Hypocapnia (low CO2 level):

  • Cerebral vasoconstriction (causes dizziness) coronary vasoconstriction (causes chest pain angina) & peripheral vasoconstriction (causes muscle coldness, pins and needles etc)
  • Increased motor & sensory nerve cell irritability
  • Sympathetic nervous system dominance
  • Reduced oxygen uptake by tissues (Bohr effect)
  • Imbalanced magnesium & calcium ratio
• LEARN BOHR EFFECT:

  • leads to hyperventilation due to less o2 being bound to haemoglobin

  
• Diagnosis:

  1. Confusing array of signs and symptoms makes diagnosis difficult ->
  2. Unnecessary tests/investigations ->
  3. Misdiagnosis ->
  4. Results in anxiety
• Cycle of HVS

  A) hyperventilation

  B) PaCO2

  C) Anxiety

  
• Assessment of DB:

  • Subjective assessment ++
  • Observation
  • Apical breathing pattern
  • Signs of air hunger - Sighs, yawns, sniffs, coughs
  • Speech
  • Personality
  • emotional state
  • Questionnaire
  • Nijmegen