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IABP Timing Optimisation — FRCA Final MCQ

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HardCardiothoracic AnaesthesiaIABP Timing OptimisationFRCA Final

A 50-year-old woman (ASA III) is in ICU post-cardiac surgery. She has an intra-aortic balloon pump in situ. The IABP is set to 1:1 augmentation. On the arterial waveform, which timing indicates optimal IABP function?

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Correct answer: C — Inflation at the dicrotic notch, deflation just before the next systole

Optimal IABP timing: inflation occurs at the dicrotic notch (onset of diastole, immediately after aortic valve closure), and deflation occurs just before the onset of the next systole (before aortic valve opening). Inflation during diastole augments diastolic pressure, improving coronary perfusion. Pre-systolic deflation reduces LV afterload (reduces the pressure against which the LV must eject), decreasing myocardial oxygen demand and improving cardiac output. Late inflation or early deflation reduces augmentation. Early inflation increases afterload.

Reference: RCOA – 2023 – Cardiothoracic anaesthesia module; Krishna M – 2009 – IABP physiology