Paul Liszewski, CRNA, DNP

Sitting on a beach chair along a shore in Orlando is a smile inducing image, but positioning a patient in the beach chair position in the operating room does not prompt the same happy feelings. In this blog I would like to start a discussion on the beach chair position and cerebral perfusion, as well as throw in a plug for the 2014 AANA Nurse Anesthesia Annual Congress in Orlando, Fla.

Over the last few months I have provided anesthesia to a number of patients for arthroscopic shoulder surgery in the beach chair position. And as luck would have it, in the same time frame I saw a short blurb related to a research article about beach chair positioning and cerebral perfusion. Specifically, the study that investigated the effect of anesthetic-induced hypotention on cerebral blood flow in the sitting position (Soeding et al., 2011). This is a hot topic in anesthesia since cerebral perfusion is monitored indirectly during these types of anesthetics and inadequate perfusion can lead to catastrophic outcomes. Retrospective survey results report very low rates of cerebral vascular events with arthroscopic shoulder surgery, but any event is a concern when a neurologic defect can be a possible outcome (Shear & Murphy, 2013). Prior to each shoulder surgery case, I try to have an open discussion with the surgeon regarding the hemodynamic limits that I plan to maintain determined by the patient’s baseline hemodynamics and cardio-/cerebro-vascular status. Each patient presents a set of variable that have to be balanced with the intent of providing the surgeon adequate conditions in which to work.


However, there is not an established set of guidelines to direct anesthetic care in these cases and we tend to draw a very conservative line in the sand regarding the mean arterial pressure (MAP) of the patient. A standard protocol for the MAP of any patient under anesthesia has been maintaining the patient within ± 20% of baseline blood pressure. This protocol is not always applicable when patients present with controlled but existing hypertension, due to the fact that maintaining a blood pressure at a higher than normal level would no doubt begin to interfere with the surgeon’s ability to clearly visualize their operative field. Another option is presented in the aforementioned article. This particular study was designed to assess cerebral blood flow (CBF) in the beach chair position on patients receiving regional anesthesia for shoulder arthroscopy combined with either sedation or general anesthetic. (Soeding et al., 2011). The CBF was measured by carotid Doppler and vasopressors were utilized as needed. It was determined that CBF was maintained when the MAP was 70 mmHg regardless of the anesthetic technique. It is important to point out that perfusion was measured at the carotid level and requires a MAP of 10-15 mmHg at the usual level of the upper arm blood pressure cuff to be comparable. While a single small study shouldn’t guide anesthetic practice, these findings can provide the anesthetist with some reassurance that they are maintaining perfusion to their patients’ vital organs when blood pressure is lower than baseline. I expect more evidence to become accessible in the near future in order for the beach chair position to be more like the day at the beach that the name implies.
Along the lines of the accessibility of research evidence, I will be attending the AANA Nurse Anesthesia Annual Congress in Orlando later this month and will be presenting a lecture on “Patient selection for ambulatory surgery”. I am faced with the challenge of determining the appropriateness of patients for outpatient surgery in my day to day practice, and this lecture grew out of my desire to be better prepared to make decisions with an evidenced-based approach. Next month’s blog will be a report from the National Congress. I hope to see some of our blog followers at the meeting as well as friends and colleagues. And I’ll be sure to make room in my schedule to enjoy some actual “beach chair” time in Orlando as well.

 

References
Shear, T., & Murphy, G. (2013, Spring-Summer). Impact of the beach chair position on cerebral perfusion: What do we know so far? Anesthesia Patient Safety Foundation Newsletter, 18-20.
Soeding, P., Wang, J., Hoy, G., Jarman, P., Phillips, H., Marks, P., & Royse, C. (2011, May). The effect of sitting upright or ’beachchair’ position on cerebral blood flow during anaesthesia for shoulder surgery. Anaesthesia and Intensive Care, 39(3), 440-448.