Respiratory Acidosis DDx


  • Decreased respiratory drive
    • CNS:
      • CVA, tumour, infection (encephalitis), haemorrhage
    • Drugs
      • Narcotics and sedatives
  • Decreased chest wall movement
    • Neurological
      • NM disorders, Guillain-Barre
      • Myasthenia gravis, demyelinating disorders
      • Tetanus
    • Toxicity
      • Muscle relaxants, organophosphates, fentanyl
    • Respiratory (Acute)
      • Trauma, surgery, chest wall deformity
      • Tension pneumothorax, pleural effusion
      • Upper airway obstruction
    • Equipment
      • Increased dead space, improper connection
  • Obstructive pulmonary disease (chronic)
    • COPD, asthma, pneumonia


  • Vasodilation, sweaty, tachycardic, mydriasis, asterixis
  • Confusion
  • Drowsy and ALOC


  • Renal compensation is slow and requires ventilatory changes for treatment
  • Increase alveolar minute ventilation


  • Usually the rise in pCO2 will stimulate the respiratory centre to increase minute volume.
  • If this fails then rapid rise in pCO2 with sedation and failure of respiratory drive and death

References and Links

CCC 700 6

Critical Care


Associate Professor Curtin Medical School, Curtin University. Emergency physician MA (Oxon) MBChB (Edin) FACEM FFSEM Sir Charles Gairdner Hospital.  Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

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