We wish to thank Dr. Lofsky for her detailed and thoughtful letter concerning our presentation in the Summer 2007 APSF Newsletter regarding the beach chair position and decreased cerebral perfusion.1 Although the 2 cases described in the newsletter article involved the use of labetalol, the other 2 cases described in our original article2 were not given labetalol. One of us (DJC) subsequently reviewed another medical legal case wherein deliberate hypotension was induced using labetalol and deep inhalation anesthesia with desflurane resulting in very stable blood pressures in the arm of 80-90/45-60 for more than an hour but leading to very prolonged wake up and permanent cognitive neurological deficits.
Dr. Lofsky may well be correct that when labetalol is used in patients before they are placed in the beach chair position (for example, in a hypertensive patient to mitigate the effects of endotracheal intubation on blood pressure and heart rate), hypotension is likely to occur under general anesthesia when they are placed upright. However, an effective dose of labetalol to accomplish this goal is usually about 10 mg intravenously,3 much less than the 50 mg dose used in case number 1. We expect treatment with direct acting vasopressor drugs by infusion or bolus will be effective in helping to maintain blood pressure at levels that will insure adequate cerebral perfusion in the upright position. We are not aware of any studies or case reports which describe acute heart failure and pulmonary edema under these circumstances, though this would be an interesting subject for further study.
As our article emphasized, we are extremely concerned about the use of deliberate hypotension in the beach chair position. Obviously, if an anesthesiologist/CRNA purposely induces deliberate hypotension with labetalol, he or she is unlikely to use vasopressors to reverse the resultant hypotension. As stated in the article, the major concern is that deliberate hypotension (regardless of how it is accomplished) in the sitting position risks inadequate cerebral perfusion leading to severe long-term neurological complications for no justifiable reason. A parallel concern is that inadvertent, unrecognized hypotension has the same effect.
We thank Dr. Lofsky for describing another risk factor, awareness of which will, we hope, improve the safety of performing shoulder surgery in the beach chair position.