Cerebral oxygen desaturation events assessed by near-infrared spectroscopy during shoulder arthroscopy in the beach chair and lateral decubitus positions.
BACKGROUND
Patients undergoing shoulder surgery in the beach chair position (BCP) may be at risk for adverse neurologic events due to cerebral ischemia. In this investigation, we sought to determine the incidence of cerebral desaturation events (CDEs) during shoulder arthroscopy in the BCP or lateral decubitus position (LDP).


METHODS
Data were collected on 124 patients undergoing elective shoulder arthroscopy in the BCP (61 subjects) or LDP (63 subjects). Anesthetic management was standardized in all patients. Regional cerebral tissue oxygen saturation (Scto(2)) was quantified using near-infrared spectroscopy. Baseline heart rate, mean arterial blood pressure, arterial oxygen saturation, and Scto(2) were measured before patient positioning and then every 3 minutes for the duration of the surgical procedure. Scto(2) values below a critical threshold (> or = 20% decrease from baseline or absolute value < or = 55% for >15 seconds) were defined as a CDE and treated using a predetermined protocol. The number of CDEs and types of intervention used to treat low Scto(2) values were recorded. The association between intraoperative CDEs and impaired postoperative recovery was also assessed.


RESULTS
Anesthetic management was similar in the BCP and LDP groups, with the exception of more interscalene blocks in the LDP group. Intraoperative hemodynamic variables did not differ between groups. Scto(2) values were lower in the BCP group throughout the intraoperative period (P < 0.0001). The incidence of CDEs was higher in the BCP group (80.3% vs 0% LDP group), as was the median number of CDEs per subject (4, range 0-38 vs 0, range 0-0 LDP group, all P < 0.0001). Among all study patients without interscalene blocks, a higher incidence of nausea (50.0% vs 6.7%, P = 0.0001) and vomiting (27.3% vs 3.3%, P = 0.011) was observed in subjects with intraoperative CDEs compared with subjects without CDEs.


CONCLUSIONS
Shoulder surgery in the BCP is associated with significant reductions in cerebral oxygenation compared with values obtained in the LDP.
Department of Anesthesiology, NorthShore University HealthSystem, University of Chicago Pritzker School of Medicine, 2650 Ridge Ave., Evanston, IL 60201, USA. dgmurphy2@yahoo.co
Glenn S
GS
Murphy
Joseph W
JW
Szokol
Jesse H
JH
Marymont
Steven B
SB
Greenberg
Michael J
MJ
Avram
Jeffery S
JS
Vender
Jessica
J
Vaughn
Margarita
M
Nisman
D000328:Adult; D001182:Arthroscopy / Q000009:adverse effects; D015415:Biomarkers / Q000097:blood; D001794:Blood Pressure; D001921:Brain / Q000098:blood supply*; D002545:Brain Ischemia / Q000097:blood / Q000209:etiology / Q000517:prevention & control*; D016009:Chi-Square Distribution; D017558:Elective Surgical Procedures; D005260:Female; D006339:Heart Rate; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D009407:Nerve Block; D010092:Oximetry; D010100:Oxygen / Q000097:blood*; D056888:Patient Positioning; D011446:Prospective Studies; D012785:Shoulder Joint / Q000601:surgery*; D019265:Spectroscopy, Near-Infrared; D016683:Supine Position; D013997:Time Factors
D015415:Biomarkers; D010100:Oxygen