Hypothermia Post Cardiac Surgery

OVERVIEW

  • common
  • multi-factorial: residual hypothermia post CPB, failure to rewarm, open thoracic cavity, cold OT, administration of cold fluids

CARDIOVASCULAR

  • increased Q -> fall in Q when T poor peripheral perfusion
  • increased myocardial ischaemia and infarction (catecholamine release mediated)
  • increased arrhythmia (AF and VT)
  • hypotension on warming because of vasodilation

RESPIRATORY

  • increased chance of laryngospasm
  • increased O2 demand (shivering)
  • shift of oxygen-Hb dissociation curve to left -> decreased O2 off loading
  • bronchodilation -> increased dead space, decreased hypoxic pulmonary vasoconstriction
  • longer time on mechanical ventilation

CENTRAL NERVOUS SYSTEM

  • decreased sensitivity to hypoxia and hypercapnoea
  • increased sensitivity to opioids and sedatives
  • decreased LOC (agitation and confusion)
  • decreased cerebral function
  • decreased protection of airway

NEUROMUSCULAR

  • increased duration of action of; NMBD, volatiles (increase in tissue solubility), propofol and fentanyl
  • increased shivering and shiver like tremor (thermal discomfort) -> increased metabolic rate, myocardial work, oxygen consumption

RENAL

  • polyria (electrolyte loss)
  • decreased ADH
  • decreased RBF and GRF

HAEMATOLOGICAL

  • coagulation and increased blood loss – reduced number of platelet activators, release of circulating anti-coagulants
  • fibrinolysis -> increased bleeding and transfusion risk
  • increased viscosity -> increased VTE risk, poor microcirculation perfusion

METABOLIC

  • hyperglycaemia (decrease peripheral utilisation of glucose)
  • acidosis from poor peripheral perfusion

INFECTIONS/WOUND

  • increase in wound infections
  • vasoconstriction -> decreased O2 supply, impairs immune function
  • slow wound healing

HEPATIC

  • decreased hepatic blood flow
  • decreased enzyme activity
  • slower drug metabolism

RESOURCE ALLOCATION

  • longer ICU stay

References and Links

LITFL


CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

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

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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