Propofol and Early Extubation After Cardiac Surgery

Abstract

In Response: We appreciate the concerns of Dr. Chaney regarding our recent paper on propofol-based anesthesia for cardiac surgery. His main concern relates to our trial design, whereby each group was given a different amount of fentanyl (and midazolam). We chose our groups carefully, after considering the published information about propofol. For most cardiac surgical patients, a large-dose opioid technique is rapidly becoming redundant and is being replaced with a balanced technique consisting of less opioid supplemented with benzodiazepine and/or volatile anesthetic. Many authors have shown that patients with good left ventricle (LV) function can be managed with a standard noncardiac anesthetic consisting of small doses of opioid (e.g., fentanyl, 5-15 micro g/kg). At our institution, as in many others, we have an increasing number of patients with LV impairment for whom higher concentrations of a volatile anesthetic would be inappropriate and so have opted for moderate doses of opioid, with smaller concentrations of volatile agent. This was the basis of our comparator group. If we had used less fentanyl in this group, we would have had to use more enflurane; we believe this would not have been tolerated in those patients with impaired LV function. Alternatively, if we had used less fentanyl, we would have placed our patients at risk of intraoperative awareness, a problem confronted by several recent authors. In our study, we had no cases of awareness. In fact, we have not had any cases of awareness using a propofol-based technique in more than 1800 subsequent cases (with all our patients being interviewed postoperatively as part of an ongoing quality assurance program). Our resultant extubation times (9.1 vs 12.3 h) were derived from all recruited patients: we did not exclude those who were extubated after 24 h. As stated in our article, many patients could have been extubated earlier (we, like many authors, have been victims of the intensive care unit relearning curve), and so further improvements can be expected. Our proposed technique can be fine-tuned to allow earlier extubation of most patients (note that 40% of the propofol group were extubated within 6 h). We now extubate nearly all cases within 2-8 h. We were also able to demonstrate that a propofol-based technique provided stable hemodynamics, minimum myocardial ischemia and a very low incidence of postoperative myocardial infarction (<2%). Paul S. Myles, MPH, MD, FANZCA John Moloney, FANZCA Department of Anaesthesia & Pain Management; Alfred Hospital; Melbourne, Australia