Adverse heart rate responses during beach-chair position for shoulder surgeries - A systematic review and meta-analysis of their incidence, interpretations and associations

BACKGROUND AND AIMS: Evaluations of adverse heart rate (HR)-responses and HR-variations during anaesthesia in beach-chair-position (BCP) for shoulder surgeries have not been done earlier. We analysed the incidence, associations, and interpretations of adverse HR-responses in this clinical setting. METHODS: We performed a meta-analysis of trials that reported HR-related data in anaesthetised subjects undergoing elective shoulder surgeries in BCP. Studies included prospective, randomised, quasi-randomised and non-randomised, controlled clinical trials as well as observational cohorts. Literature search was conducted in MEDLINE, EMBASE, CINHAL and the Cochrane Central Register of Controlled Trials of the 21(st) century. In the first analysis, we studied the incidence and associations of bradycardia/hypotension-bradycardia episodes (HBE) with respect to the type of anaesthesia and different pharmacological agents. In the second, we evaluated anaesthetic influences, associations and inter-relationships between monitored parameters with respect to HR-behaviours. RESULTS: Among the trials designed with bradycardia/HBE as a primary end point, the observed incidence of bradycardia was 9.1% and that of HBE, 14.9% and 22.7% [(for Interscalene block (ISB) ± sedation) subjects and general anaesthesia (GA) + ISB, respectively]. There was evidence of higher observed risk of developing adverse HR-responses for GA subjects over ISB (Risk Difference, P < 0.05). Concomitant use of β-agonists did not increase risk of HBEs (P = 0.29, I(2)= 11.4%) or with fentanyl (P = 0.45, I(2)= 0%) for ISB subjects (subgroup analysis). Fentanyl significantly influenced the HR-drop over time [meta-regression, estimates (standard error), 14.9 (5.4), 9.8 (4.3) and 17 (2.6); P = 0.007, 0.024 and <0.001; for early, mid and delayed periods, respectively] in GA subjects. With respect to number of subjects experiencing cerebral desaturation events (CDEs), total intravenous anaesthesia (TIVA)- propofol had higher risk over inhalational anaesthesia (P = 0.006, I(2) = 86.7%). Meta-correlation analysis showed relationships between the HR and rSO(2)(regional cerebral oxygen saturation) or SjvO(2)(jugular venous oxygen saturation) values (r = 0.608, 95%CI, 0.439 to 0.735, P < 0.001, I(2)= 77.4% and r = 0.397, 95%CI, 0.151 to 0.597, P < 0.001, I(2)= 64.3%, respectively). CONCLUSIONS: There is not enough evidence to claim the associations of adverse HR-responses with any specific factor. HR-fall is maximal with fentanyl and its variability is associated with changes in rSO(2). Fall in rSO(2) could be the common link triggering adverse HR-responses in BCP.