Key result
Assuming the beach-chair position during shoulder surgery resulted in a 24.77% decrease in MAP and a 27.96% decrease in Vmca, with a significant linear correlation between the two (r = 0.77).
Why the study?
Hypotension and cerebral hypoperfusion in the beach-chair position during general anesthesia carry neurologic risks, but data on monitoring cerebral perfusion remain scarce.
Does the beach-chair position affect mean arterial pressure and middle cerebral artery velocity in patients undergoing shoulder surgery?
Observational (n=20)
No
Does the beach-chair position affect mean arterial pressure and middle cerebral artery velocity in patients undergoing shoulder surgery?
Effect estimate: Pearson's r = 0.77
p-value: p=<0.001
The beach-chair position during shoulder surgery significantly decreases mean arterial pressure and cerebral blood flow velocity, which can be reliably monitored using transcranial Doppler.
Beach-chair positioning was associated with correlated MAP and cerebral flow velocity drops; leaves open whether MAP targets preserve cerebral perfusion in anesthesia.
Background Hypotension and cerebral hypoperfusion, commonly encountered in beach-chair position under general anesthesia, carry the risk of neurologic complications. There is a paucity of data on monitoring cerebral perfusion. Our objective was to compare the mean arterial pressure (MAP) and middle cerebral artery velocity (Vmca) in the supine and beach-chair position and estimate its correlation during hypotension. Materials and Methods Twenty ASA class I and II patients undergoing elective shoulder surgery in beach-chair position were included in the study. MAP was measured invasively with the pressure transducer leveled to the phlebostatic axis. Vmca was measured with a 2 MHz transcranial Doppler (TCD) probe through the temporal window. Both MAP and Vmca were measured at baseline after anesthetic induction in the supine position (BL), on assuming the beach-chair position (AP), at steady-state hemodynamics in beach-chair position (P1), whenever there was a drop in MAP > 20% (P2), and on the restoration of MAP (P3). Results A mean decrease in MAP and Vmca by 24.76% and 27.96%, respectively, from supine to beach-chair position with a significant linear correlation between MAP and Vmca along with a Pearsons' coefficient of 0.77 was seen. A change in MAP of 1 mm of Hg resulted in a change in Vmca by 0.53 cm/sec (p < 0.05). Conclusion A significant decrease in MAP and Vmca was observed in the beach-chair position. TCD could be used as a point-of-care noninvasive technique to reliably assess cerebral perfusion.
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Antony et al. (2021) conducted an observational in Elective shoulder surgery (n=20). Beach-chair position vs. Supine position was evaluated on Correlation between changes in mean arterial pressure (MAP) and middle cerebral artery flow velocity (Vmca) (Pearson's r = 0.77, p=<0.001). Assuming the beach-chair position during shoulder surgery resulted in a 24.77% decrease in MAP and a 27.96% decrease in Vmca, with a significant linear correlation between the two (r = 0.77).
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