CPB Safety Checklist
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Direct answer
Going on bypass is a three-way verbal contract: surgeon, anaesthetist and perfusionist each confirm aloud — heparin given, ACT at target, cannulae placed, alarms armed, prime de-aired — before a single litre flows. The safety system around that moment is layered hardware (level sensor, bubble detector, pressure monitors, all interlocked to stop the pump), a fixed initiation sequence, and drilled responses to the catastrophes the checklist exists to prevent: massive air embolism, aortic dissection, reservoir emptying and power failure. Incidents on bypass are rarely single-cause; the checklist works because it closes several independent holes at once, and it fails when it is ticked silently instead of spoken.
What you must remember
- Pre-bypass essentials: ACT at or above target, arterial and venous cannulae secured, a pulsatile backflow and line-pressure check on the arterial side, anaesthesia deepened (awareness risk peaks at initiation), monitors zeroed, cell saver ready.
- Machine checks: pump occlusion and rotation direction, arterial line filter purged, bubble detector tested and interlocked, level sensor set with a low-volume alarm on the venous reservoir, transducers on arterial and cardioplegia lines, hand crank present, heater-cooler functional with water temperature capped near 42 degrees C, sweep gas connected through a correct blender.
- Going on pump: announce, unclamp arterial, observe line pressure and pulsatility, release the venous clamp gradually, ramp flow to target over one to two minutes, stop the ventilator at full flow, then confirm pupils and conjunctivae (venous drainage) and draw the first on-pump gas.
- Ventilation stops at full flow because pulmonary blood flow has been diverted; the lungs are held gently inflated, not collapsed.
- On-pump surveillance: venous level, MAP, arterial line pressure, in-line venous saturation, temperature gradients (keep water-to-blood difference under about 10 degrees C so gas does not come out of solution), gases, ACT and haematocrit every 30 minutes, urine output, cardioplegia volumes and times, every drug added to the reservoir recorded.
- Massive air embolism drill: stop the pump, clamp arterial and venous lines, head down and left lateral, surgeon aspirates air from the aorta, retrograde cerebral perfusion via the superior vena cava, 100% oxygen, consider hyperbaric therapy and cooling.
- Low reservoir level alarm: reduce flow first, then find the cause — kinked drainage, cannula malposition, air lock, hidden blood loss; add volume as needed.
- Closed-loop communication: every command and readback repeated verbatim; incidents are analysed as systems failures (the Swiss-cheese model) and near misses reported, not absorbed.
The readback, word for word
Perfusionist: "ACT 512, prime de-aired, gases on, alarms set — ready to go on?" Surgeon: "Arterial in, test clamp off — go on." Perfusionist: "Arterial line pressure 95, good pulsation... venous clamp off, coming to two litres... four litres, full flow. Anaesthesia, ventilator off." Anaesthetist: "Ventilator off, pupils mid-position, conjunctivae clear." The first five minutes then run as a litany of numbers: level steady, MAP 62 with the anaesthetist titrating, in-line venous saturation 71%, sweep 4 at FiO2 0.6, first arterial gas PaO2 240. Rehearsed exactly this way, the readback doubles as the checklist — nothing is ticked that was not said aloud.
The point of scripting: initiation is the noisiest, most interruption-prone moment of the case, and a spoken sequence survives interruption where a remembered one does not — which is why programmes auditing near misses find initiation and weaning over-represented.
Where the routine fails
Checklist fatigue tops the list: the card signed from memory mid-task, the machine self-test treated as coverage for the whole system — which it is not, because the self-test ends at the machine's edge; the gas hose, the heater-cooler water temperature and the hand crank are checked by no self-test. Communication failures follow: "come down" half-heard as "come off" over diathermy is the argument for verbatim readback. And the low-level alarm sets its own trap: the instinct is to speed up; the drilled answer is to reduce flow first, because a pump running dry is the fastest route to massive air embolism. Every element is a hole in cheese; the discipline is keeping several layers aligned.
Frequently asked questions
What ACT must be confirmed before initiating bypass?
Above 400 seconds by kaolin ACT (many centres require 480), checked immediately before going on pump.
What is the first response to a low venous reservoir level alarm?
Reduce the pump flow, then find and fix the cause — kinked drainage line, cannula malposition, air lock or hidden blood loss — adding volume as needed.
What are the first steps in massive air embolism on bypass?
Stop the pump; clamp arterial and venous lines; head down and left lateral position; surgeon aspirates air from the aorta; retrograde cerebral perfusion via the SVC; 100% oxygen.
How often are gases, ACT and haematocrit repeated on pump?
Roughly every 30 minutes, and after any significant circuit event or temperature change.
Who confirms the decision to go on bypass?
All three — surgeon, anaesthetist and perfusionist — through an explicit verbal exchange; no single voice starts the pump alone.
Why is the ventilator stopped at full flow?
Pulmonary blood flow has been diverted to the circuit, so ventilation is unnecessary; the lungs are held slightly inflated until weaning.