This is a condensed revision of Ray Raper's chapter on post-op management of cardiothoracic surgical patients in the ICU. It has been expanded upon by details from the 2004 update to the 1999 AHA guidelines relating to the management of patients recovering from coronary artery bypass graft surgery. The routine care of such patients is never asked about in the written papers, mainly because the college is usually asking about the management of complications, which should not form a part of routine post-operative care.
The perioperative mortality for these people is on average about 3%.
The post-operative course, and the anticipated problems, can be summarised as follows:
- Immediate management following return from theatre
- Management in the first 4 hours post op
- Assessment of readiness for extubation
- Management of the post-operative respiratory failur
Upon return from theatre:
- the patient will be intubated
- Mechanical ventilation (mandatory mode) should be commenced
- No unique recommendation - standard ventilation
Circulatory support and monitoring
- A healthy elective patient is likely to be cold, vasoconstricted, and on a GTN infusion to decrease coronary vascular resistance
- PA catheter: get a thermodilution cardiac output measurement
- To assess the position of ETT, drains, PA catheter or central line
- To assess the re-expansion of the lungs
- To assess for coronary ischaemia
- To assess for adequacy of reversal of heparinisation
In the first 4 hours:
- Wean off mandatory mode and transition to a patient-triggered pressure support mode
- Wean FiO2 as tolerated
- One typically allows the patient to re-warm spontaneously. Rarely is any extraordinary heating required.
- Anticipate hypotension as passive rewarming takes place; GTN can be weaned off.
- Watch for cardiac tamponade
- Carefully titrate vasopressors to increase MAP
- Carefully titrate vasodilators to prevent excessive afterload
- aim for a MAP of 90-100 (according to some authors) - lower if the aorta has been opened
- Isotonic crystalloids or 4% albumin - seems to matter very little
- Anticipate polyuria in the first 6 hours
- Anticipate early hypokalaemia and hypomagnesaemia
- Anticipate late hyperkalaemia (especially from patients on chronic ACE-inhibitors)
- Aim for a potassium of 4.5-5.0, magnesium 1.0-1.5
In this fashion, 4 hours pass.
Are they ready for extubation?
There are a few conditions they must meet.
- Hemodynamic stability (ok, some noradrenaline is permissible)
- Warmth (the return to normothermia)
- Alertness (they need to be waking up)
- Some degree of spontaneous respiratory effort
The majority of uncomplicated CABG patients tend to meet these criteria after 4 hours or so.
And those that don't? Why aren't they ready for extubation yet?
The temperature of the patient, and their level of alertness, is something well within your control. Warm them, wake them up, take away the sedating infusions - all of these things will help.
However, the hemodynamic stability and the ventilation are slightly more tricky.