CICM SAQ 2015.1 Q2
Question
List the complications and their likely underlying mechanisms specifically related to cardiopulmonary bypass that may be seen in the ICU following cardiac surgery.
Answer
Answer and interpretation
a) Effects related to blood contact with non-biologic surfaces and blood-gas interfaces
- Activation of coagulation cascade- consumptive coagulopathy, thromboembolic phenomena, haemolysis, rarely TTP.
- Systemic inflammatory response syndrome due to leucocyte and complement activation, cytokine release and expression of adhesion molecules- vasodilatory shock, fever, acute lung injury, liver dysfunction, multiorgan dysfunction.
- Platelet dysfunction
b) Effects related to non-pulsatile flow
- Renal dysfunction
- Cerebrovascular events, watershed infarcts, neurocognitive dysfunction
- Splanchnic ischaemia
c) Effects related to haemodilution
- Dilutional coagulopathy, anaemia.
- Electrolyte abnormalities
d) Effects of hypothermia
- Coagulopathy
- Decreased tissue oxygen delivery
- Insulin resistance and hyperglycaemia
e) Effects of heparin and protamine
- Residual heparinisation leading to bleeding
- Increased pulmonary vascular resistance and right ventricular dysfunction from protamine, allergic reactions to protamine
f) Effects related to aortic manipulation (cross-clamping and proximal grafts)
- Systemic embolisation with potential for neurologic, mesenteric and renal dysfunction.
- Difficulty with myocardial protection resulting in postoperative myocardial dysfunction (especially right-sided) due to stunning or infarction
g) Other
- Left phrenic nerve palsy (surgical injury, use of cold cardioplegia “slush”)
- Left lower lobe collapse (poor re-inflation post bypass, phrenic nerve injury)
- Pass rate: 63%
- Highest mark: 8.8
Additional comments:
- Candidates who failed did not address complications specific to CP bypass and/or did not describe the underlying mechanisms. Some answers were poorly structured with a tendency to repeat points.
- The above answer template is not the only way to structure the answer, for example the complications could be classified by body system affected.
Examination Library
CICM
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.
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