Effects of Dexmedetomidine on Respiratory Mechanics in Elderly Patients Undergoing Laparoscopic Colorectal Tumor Resection: A Randomized Double-Blinded Trial.

Perioperative pulmonary dysfunction frequently occurs in elderly patients undergoing procedures involving pneumoperitoneum and the Trendelenburg position. This study aimed to evaluate the effect of Dex on respiratory mechanics in elderly patients undergoing laparoscopic resection of colorectal tumors. This prospective randomized double-blind clinical trial had 64 elderly patients scheduled for laparoscopic resection of the rectum or sigmoid colon, who were assigned to receive either Dex or a placebo. The primary aim was the oxygenation index (OI), while the secondary objectives included respiratory mechanics, hemodynamic parameters, and postoperative recovery outcomes. Five patients were excluded and a total of 59 patients were included for analysis. Linear mixed-effects analysis revealed that while Dex significantly diminished intraoperative intrapulmonary shunting (P = 0.036), it substantially reduced lung compliance (P < 0.001), tidal volume (P = 0.035), OI (P = 0.013), while increasing plateau pressure (P = 0.047) over time in elderly patients undergoing laparoscopic colorectal surgery compared to the control group. Moreover, patients administered Dex exhibited reduced intraoperative heart rate (P < 0.001), systolic blood pressure (P < 0.001), and mean arterial pressure (P = 0.044) compared to the control group over time, especially in the time of extubation; however, these parameters in the Dex group remained within clinically acceptable limits. With the exception of intraoperative urine output, which was significantly higher in the Dex group compared to the control group (P = 0.003), no statistically significant differences were observed between the two groups in the other measured outcomes. Intraoperative administration of Dex in elderly patients undergoing laparoscopic colorectal surgery results in a reduction of lung compliance, an increase in plateau pressure, and a deterioration of the OI.