I love that a new intern in August is making the decision to extubate an ESRDer s/p a 4v CABG who is on 2 pressors 2 inotropes and oxygenating poorly.
Supervisory culture may that institution may need a tweak.
Cognitus - as described above, extubation is like a cardiopulmonary stress test; it raises preload, raises afterload, increases the work of breathing (VO2 and VCO2), and lets you give oxygen less reliably. So if you're going to extubate someone, you have to know, or have a good suspicion, that they will tolerate it from all of those standpoints.
A patient with those comorbidities on 4 drips doesn't sound hemodynamically tuned up at all, and the oxygenation was marginal. Best plan would have been to let a few hours pass and see if/how oxygenation or hemodynamics improved. Your patient sounds vasoplegic, possibly volume overloaded, and with a big hit to inotropy/lusitropy and you'd expect.
Of course, to know if the hemodynamics improved, you have to have some more numbers. What was your pump and crossclamp time? Did the patient need those drips pre-pump or everything added to come off or after that? Did the patient have a Swan? Did you have PAP's, PCWP, CO/CI, SVR? One case where its usefulness in titrating drips and diagnosing the etiology of the need for those drips is obvious, IMO.