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Respiratory Acidosis DDx

Causes

  • 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

Clinical

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

Correction

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

NOTE:

  • 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

CCC Differential Diagnosis Series

NEURO

Anosmia, Ataxia, Blepharospasm, Bulbar and Pseudobulbar palsy, Central Pontine Myelinosis, Cerebellar Disease, Chorea, Cranial nerve lesions, Dementia, Dystonia, Exophthalmos, Eye trauma, Facial twitches, Fixed dilated pupil, Horner syndrome, Loss of vision, Meningism, Movement disorders, Optic disc abnormality, Parkinsonism, Peripheral neuropathy, Radiculopathy, Red eye, Retinal Haemorrhage, Seizures, Sudden severe headache, Tremor, Tunnel vision

RESP

Bronchial breath sounds, Bronchiectasis, High airway pressures, Massive haemoptysis, Sore throat, Tracheal displacement

CVS

Atrial Fibrillation, Bradycardia, Cardiac Failure, Chest Pain, Murmurs, Post-resuscitation syndrome, Pulseless Electrical Activity (PEA), Pulsus Paradoxus, Shock, Supraventricular tachycardia (SVT), Tachycardia, VT and VF, SVC Obstruction

GIT

Abdominal distension, Abdominal mass, Abdominal pain, Asterixis, Dysphagia, Hepatomegaly, Hepatosplenomegaly, Large bowel obstruction, Liver palpation abnormalities, Lower GI haemorrhage, Malabsorption, Medical causes of abdominal pain, Rectal mass, Small bowel obstruction, Upper GI Haemorrhage

GUT

Genital ulcers, Groin lump, Scrotal mass, Urine colour, Urine Odour, Urine transparency

MSK

Arthritis, Shoulder pain, Wasting of the small muscles of the hand

DERM

Palmar erythema, Serious skin signs in sick patients, Thickened Tethered Skin, Leg ulcers, Skin Tumour, Acanthosis Nigricans

ENDO

Diabetes Insipidus, Diffuse Goitre, Gynaecomastia, Hirsutism, Hypoglycaemia, SIADH, Weight Loss

HAEM

Splenomegaly

PAEDS

Floppy infant 

MISC

Anaphylaxis, Autoimmune associated diseases, Clubbing, Parotid Swelling, Splinter haemorrhages, Toxic agents and abnormal vitals, Toxicological causes of cardiac arrest

IMAGING

CHEST: Atelectasis, Hilar adenopathy, Hilar enlargement on CXR, Honeycomb lung, Increased interstitial markings, Mediastinal widening on mobile CXR, Pulmonary fibrosis, Pseudoinfiltrates on CXR, Pulmonary opacities on CXR,
ABDO: 
Gas on abdominal X-ray, Kidney mass,
BRAIN: 
Intracranial calcification, Intracranial structures with contrastVentriculomegaly,
OTHER: Pseudofracture on X-Ray

LABS

LOW: Anaemia, Hypocalcaemia, hypochloraemia, Hypomagnesaemia

HIGH: Bilirubin and Jaundice, HyperammonaemiaHypercalcaemia, Hyperchloraemia, Hyperkalaemia, Hypermagnesaemia

ACID BASE: Acid base disorders, Resp. acidosis, Resp. alkalosis,

Creatinine, CRP, Dipstick Urinalysis, Laboratory Urinalysis, Liver function tests (LFTs), Pleural fluid analysis, Urea, Urea Creatinine Ratio, Uric acid, Urinalysis, Urine Electrolytes


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CCC 700 6

Critical Care

Compendium

BA MA (Oxon) MBChB (Edin) FACEM FFSEM. Emergency physician, 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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