The influence of anesthetic drug strategy on the incidence of post induction hypotension in elective, non-cardiac surgery - A prospective observational cohort study

Study objectives: To identify the influence of modifiable factors in anesthesia induction strategy on post-induction hypotension (PIH), specifically the type, dosage and speed of administration of induction agents. A secondary aim was to identify patient related non-modifiable factors associated with PIH.

Design: Single-center, prospective observational cohort study.

Setting: Operating room.

Patients: Adult, ASA I-IV patients undergoing elective, non-cardiac surgery under general anesthesia (GA).

Interventions: None.

Measurements: Continuous non-invasive blood pressure using finger-cuff technology. PIH was defined as mean arterial pressure (MAP) <65 mmHg ≥1 min, and, separately, as a > 30 % decrease from baseline MAP ≥1 min.

Main results: Study measurements were performed in 760 patients, of which 720 were suitable for analysis. A total of 238 patients (33.1 %) experienced PIH according to the 65 mmHg threshold, and 287 (39.9 %) using the 30 % decrease in MAP threshold. Remifentanil administration was associated with increased risk of PIH according to either definition (MAP <65 mmHg: OR 1.88, 95 %CI 1.31-2.69, p < 0.001, 30 % MAP decrease: OR 1.66, 95 %CI 1.15-2.40, p = 0.007). Pre-emptive vasopressor use (before or during first minute of GA) was associated with reduced risk of PIH (MAP <65 mmHg: OR 0.65, 95 %CI 0.45-0.95, p = 0.027, MAP 30 % decrease: OR 0.58, 95 %CI 0.40-0.84, p = 0.004). Speed of propofol bolus administration, propofol bolus dose, and esketamine use were not associated with PIH in multivariable analysis. Propofol bolus dose decreased with increasing age and American Society of Anesthesiologists physical status classification.

Conclusions: PIH was common in this patient cohort, regardless of the definition used. Two of the five examined modifiable factors were associated with PIH: remifentanil infusion was associated with an increased risk, and pre-emptive vasopressor use was associated with a decreased risk of PIH. No association between propofol dose and PIH was found, most likely due dose adjustment based on clinical assessment rather than a true absence of effect.

Clinical registration number: This study was registered in the Dutch Medical Research in Humans (OMON) register on 18 June 2019 (ID: NL7810). The study was approved by the Medical Ethics Committee of the Amsterdam UMC, location AMC, the Netherlands in December 2018 (NL 6748.018.18; 2018).