ABG changes in Cardiac Arrest and CPR

OVERVIEW

The degree of acid-base abnormality during cardiac arrest and cardio-pulmonary resuscitation (CPR) is dependent on a number of variables, which include:

  1. cause of arrest
  2. duration of arrest when arterial blood gas (ABG) is taken
  3. the quality of the CPR and ventilation the patient is receiving
  4. temperature of the patient when ABG taken
  5. drugs administered during arrest (ie. Adrenaline and NaHCO3)

METABOLIC ACIDAEMIA

  • lactic acidosis from hypoperfusion (Type A) and/or B2-agonist effect of adrenaline administration (Type B2)

RESPIRATORY ACIDAEMIA OR ALKALOSIS

  • may be inadequately ventilated leading to acidaemia (especially if not intubated)
  • iatrogenic hyperventilation is common during cardiac arrest, causes respiratory alkalosis

LOW HCO3-

  • from combined metabolic and respiratory acidosis

LOW PaO2

  • if patient only receiving air (FiO2 0.21)
  • aspiration, pulmonary oedema, pulmonary embolus, primary respiratory pathology

NEGATIVE BASE EXCESS

  • quantifying degree of metabolic acidosis

HYPERKALAEMIA

  • from cell death and loss of cell membrane integrity and acidosis

HYPERGLYCAEMIA

  • stress response

References and Links

LITFL

CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the  Clinician Educator Incubator programme, and a CICM First Part Examiner.

He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.

His one great achievement is being the father of three amazing children.

On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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