Effects of Blood Pressure Management Based on Non-Invasive Heart Function Monitoring on Reducing Postoperative Hypotension in Elderly Patients Undergoing Total Knee Arthroplasty: A Randomized Controlled Trial.

BACKGROUND

Postoperative hypotension is a common symptom in elderly patients undergoing total knee arthroplasty (TKA), which is associated with intraoperative blood pressure (BP) management. The study aimed to explore the causes of perioperative hypotension in TKA elderly patients and analyze the effects of BP management strategies based on noninvasive heart function monitoring on reducing postoperative hypotension.

METHODS

A total of 176 elderly TKA patients were divided into four groups: the tourniquet group (group T), the nontourniquet group (group N), the goal-oriented BP management tourniquet group (group GT), and the goal-oriented BP management nontourniquet group (group GN). Patients in groups T and GT received TKA with a tourniquet. The BP of patients in groups GT and GN was maintained based on noninvasive heart function monitoring. The mean arterial pressure (MAP), index of cardiac contractility (ICON), stroke volume (SV), and other circulatory indicators were measured using the noninvasive cardiometer monitor at five time points, including before anesthesia (T1), after anesthesia (T2), after completion of the osteotomy (T3), after suturing (T4), and after leaving the postanesthesia care unit (T5). The frequency of postoperative hypotension within 24 hours was recorded, and the incidence of hypotension was calculated.

RESULTS

The ICON, SV, and MAP were lower in groups N and GN than in groups T and GT at T3 (P < 0.05). The ICON, SV, and MAP were lower in group N than in groups GN at T4 and T5 (P < 0.05), and no significant difference was observed between groups T and GT (P > 0.05). The incidence of postoperative hypotension within 24 hours was higher in group N (47.1%) (P = 0.007) than in group GN (21.6%), group T (19.4%), and group GT (14.8%).

CONCLUSIONS

Postoperative hypotension in elderly patients undergoing TKA with a nontourniquet was associated with decreased myocardial contractility. Enhancing myocardial contractility based on non-invasive cardiac function monitoring reduced the incidence of postoperative hypotension.