To the Editor
Since I have spent a significant part of my academic career investigating the fidelity and accurate recording of invasive blood pressure measurements, I was quite intrigued by the discussion of adverse neurologic outcomes after shoulder arthroscopy in the beach chair position, and how these adverse outcomes may relate to the measurement of blood pressure.1-4 In my opinion Dr. Munis hones in on the relevant issues.4 Transmural pressure at the level of the head is absolutely NOT the issue; perfusion pressure is! As such, memorizing correction factors for blood pressure at the level of the head (while the patient is in the beach chair position), while taking readings at the level of the heart is a waste of time and effort. Not only is it a waste of time, it diverts one’s focus from the real issue. As Dr. Munis points out, the real issue for anesthesiologists is to what degree blood pressure can be lowered from preoperative levels. What exactly is a safe blood pressure? The problem is—we don’t know. And it is probably true that decrements in blood pressures that are safe in some patients may not be safe in others. Dr. Munis should be commended for directing our attention to the real issue in these tragic cases; and pointing out why we should not be distracted by the nonissues of transmural pressures, altering transducer height, and “correction” formulas.
Bruce Kleinman MD
Maywood, IL 60153
- Cullen DJ, Kirby RR. Hazards of beach chair position explored (letter 1). APSF Newsletter 2008; 22(4): 81.
- Budnyk S. Hazards of beach chair position explored (letter 2). APSF Newsletter 2008; 22(4): 81.
- Cucchiara RF. Hazards of beach chair position explored (letter 3). APSF Newsletter 2008; 22(4): 81.
- Munis J. The problems of posture, pressure, and perfusion: cerebral perfusion pressure defined. APSF Newsletter 2008; 22(4): 82-83.