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Background: To test the hypothesis that Hypotension probability indicator (HPI) driven hemodynamic protocol use may decrease the exposition to hypotension (mean arterial pressure below 65 mmHg) during supratentorial intracranial procedures., Methods: Patients undergoing supratentorial tumor resection under general anesthesia (ASA 1-3) were included into this randomized single center-controlled pilot trial. Patients in the control group (COV, N.=20) were managed based on the institutional standard to avoid hypotension. Patients in the intervention (INT, N.=20) group were managed using a protocol triggered by the HPI above 85 based on the stroke volume variation, dynamic elastance, and cardiac index parameters. The number of patients experiencing hypotension (mean arterial pressure below 65 mmHg) during the whole procedure and anesthesia maintenance phase was the primary outcome variable. The number of hypotensive periods, time spent in hypotension, and hypotension dose served as secondary outcome variables. Other clinically relevant parameters and postsurgical outcomes were screened., Results: The number of patients who never experienced hypotension was significantly lower in the INT group during the anesthesia maintenance phase (10 (50%) vs. 16 (80%); P=0.049). In several other hemodynamic outcomes, a distinct numerical, but statistically non-significant trend towards lower hypotension exposition was observed. There were no significant differences in clinically relevant parameters., Conclusions: In this pilot trial, the HPI-based protocol decreased the incidence of hypotension during the anesthesia maintenance but non-significant trends among secondary outcomes were also documented. Larger trials are needed to confirm our findings.

Intermittent blood pressure (BP) monitoring is the standard-of-care during low and intermediate risk anaesthesia, yet it could lead to delayed recognition of BP fluctuations. Perioperative hypotension is known to be associated with postoperative complications. Continuous, non-invasive methods for BP monitoring have been developed recently. We have tested a novel non-invasive, continuous monitor (using the volume clamp method) to assist with maintaining BP in safe ranges for patients undergoing surgery in a beach chair position. Forty adult patients undergoing thyroid gland surgery in an upright position were included in this prospective randomised controlled trial. Patients were equally allocated to the group with continuous monitoring of BP using the CNAP® Monitor and to the control group managed using an intermittent oscillometric BP cuff. The absolute and proportional time spent outside the range of ±20% of the target BP along with other hemodynamic and clinical parameters were evaluated. The continuous monitoring decreased the anaesthesia time spent below -20% pressure range [absolute: 12 min (4-20) vs. 27 min (16-34); p=0.001; relative to procedure length: 14% (7-20) vs. 33.5% (17.5-53); p=0.003]. No significant differences were observed in postoperative morbidity or in hospital length of stay. Continuous non-invasive BP monitoring via the CNAP® Monitor allows for better BP management in patients undergoing surgery in a beach chair position. In our randomised trial the time spent in hypotension was significantly shorter using continuous monitoring.