Continuous versus intermittent noninvasive blood pressure monitoring during beach chair position for shoulder surgery

BACKGROUND: Arthroscopic shoulder surgery is frequently conducted in the beach chair position. Haemodynamic instability with hypotension and reduction of cerebral perfusion has been widely reported. OBJECTIVE: To determine whether a continuous noninvasive blood pressure monitoring using a finger-cuff reduces hypotension during arthroscopic shoulder surgery compared to standard oscillometric brachial pressure monitoring. DESIGN: Randomised controlled trial. SETTING: Orthopaedic operating theatre of IRCCS Fondazione Policlinico Universitario Agostino Gemelli of Rome, Italy. PATIENTS: Sixty patients (30 per group) scheduled for arthroscopic shoulder surgery in beach chair position under brachial plexus block plus general anaesthesia. INTERVENTIONS: All patients received noninvasive continuous haemodynamic monitoring with finger-cuff. Patients were then randomised to unblinded continuous finger-cuff arterial pressure monitoring or to intermittent oscillometric arterial pressure monitoring. MAIN OUTCOME MEASURES: Primary outcome measure was time-weighted average mean arterial pressure under the threshold of 65 mmHg during surgery. Secondary outcomes were the incidence of cerebral oxygen desaturation episodes, the incidence of severe hypotensive episodes, and the time to correct the hypotensive episode in minutes. RESULTS: The time weighted average mean [IQR] arterial pressure under the threshold of 65 mmHg was 0.41 [0.04, 0.98] mmHg in the finger-cuff group and 0.69 [0.21, 2.20] mmHg in the Control group, with a Hodges-Lehman estimator of -0.24 (95% confidence interval: - 0.75 to 0.07) mmHg ( P = 0.137).No difference in the incidence of severe hypotensive events, defined as a mean arterial pressure less than 50 mmHg, was detected between the two groups ( P = 0.017). Cerebral tissue oxygen saturation values were stable throughout the vast majority of the monitoring period, with absolute values less than 60% and relative values less than 10% of the baseline being uncommon in the two cohort of patients. A positive correlation between simultaneous tissue oxygen saturation values and mean arterial pressure was found ( r = 0.298 95% confidence interval 0.283 to 0.312, P < 0.001). CONCLUSIONS: Continuous noninvasive arterial pressure monitoring is not effective in reducing the amount of intra-operative hypotension during shoulder surgery performed in the beach chair position compared to intermittent oscillometric monitoring. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT05143632.