112. Respiration in Abnormal Conditions and Abnormal Respirations – Quiz

📌 Professor’s Notes: Quick Revision

High-yield revision notes for rapid review before university examinations.

• Abnormal respiration occurs in several respiratory, metabolic, and neurological disorders. Recognition of abnormal breathing patterns provides important clues to the underlying disease and has great clinical significance.
• Asphyxia is a life-threatening condition characterized by hypoxia with hypercapnia due to inadequate ventilation. Common causes include airway obstruction, drowning, strangulation, suffocation, foreign body aspiration, and chest compression.
  • It progresses through three stages:
    • Stage of exaggerated breathing: Deep, rapid breathing, severe dyspnea, anxiety, and cyanosis.
    • Stage of convulsions: Irregular respiration, generalized convulsions, tachycardia, hypertension, and loss of consciousness.
    • Stage of exhaustion and collapse: Respiratory depression, hypotension, dilated pupils, disappearance of reflexes, respiratory arrest, and death if untreated.
• Hypercapnia is an increase in arterial carbon dioxide tension (PaCO₂) caused mainly by hypoventilation. Other causes include respiratory center depression, neuromuscular disorders, severe pulmonary disease, and chest wall disorders.
  • Mild hypercapnia stimulates respiration.
  • Severe hypercapnia causes respiratory acidosis, confusion, drowsiness, coma, and respiratory depression.
  • Type I respiratory failure causes hypoxemia without hypercapnia, whereas Type II respiratory failure causes both hypoxemia and hypercapnia.
• Hypocapnia results from hyperventilation, which lowers PaCO₂ and causes respiratory alkalosis.
  • It produces cerebral vasoconstriction, reducing cerebral blood flow and causing dizziness, blurred vision, paresthesia, and light-headedness.
  • Reduced ionized calcium may produce carpopedal spasm and Chvostek sign.
• Drowning is a form of suffocation caused by submersion.
  • Freshwater drowning causes hemodilution due to absorption of water.
  • Seawater drowning causes pulmonary edema because hypertonic seawater draws fluid into the alveoli.
  • Laryngospasm may prevent water entry, with death resulting mainly from severe asphyxia.
• Respiratory acidosis develops due to inadequate elimination of carbon dioxide, whereas respiratory alkalosis results from excessive carbon dioxide loss during hyperventilation, such as at high altitude.
• Periodic breathing consists of alternating periods of apnea and hyperventilation due to fluctuations in arterial carbon dioxide around the apneic threshold.
• Cheyne–Stokes respiration is a pathological form of periodic breathing with alternating apnea and waxing-and-waning tidal volume. It occurs in heart failure, renal failure, neurological disorders, high altitude, premature infants, and during deep sleep.
• Other important abnormal breathing patterns:
  • Kussmaul breathing: Deep, rapid breathing seen in diabetic ketoacidosis and severe metabolic acidosis; helps remove carbon dioxide and compensate for acidosis.
  • Biot’s respiration: Irregular breathing with sudden apnea due to medullary or brainstem lesions, meningitis, increased intracranial pressure, or opioid toxicity.
  • Obstructive sleep apnea: Recurrent upper airway obstruction during sleep causing loud snoring, daytime sleepiness, hypertension, arrhythmias, and cardiovascular disease.
  • Sudden infant death syndrome (SIDS): Sudden unexplained death of an infant, probably due to abnormalities of autonomic and respiratory control.
  • Psychogenic hyperventilation (hysteric hyperpnea): Anxiety-induced hyperventilation causing respiratory alkalosis, dizziness, paresthesia, and carpopedal spasm.