Incidence, characteristics and risk factors for alveolar recruitment maneuver-related hypotension in patients undergoing laparoscopic colorectal cancer resection

Table 4 Multivariate analysis: Adjusted risk factors for alveolar recruitment maneuver-related hypotension

Risk factors	OR (95%CI)	P value
Age < 74 yr	1 (Reference)
Age ≥ 74 yr	2.97 (1.24, 7.09)	0.014
Intraoperative blood loss < 150 mL	1 (Reference)
Intraoperative blood loss ≥ 150 mL	2.88 (1.13, 7.30)	0.012
PIP at T2 ≥ 24 cm H2O	1 (Reference)
PIP at T2 < 24 cm H2O	3.06 (1.28, 7.31)	0.026

Alveolar recruitment maneuver (ARM)-related hypotension: Mean arterial pressure < 60 mmHg during an ARM or within 5 min after an ARM. Three different models (A, B, and C) were used to identify risk factors, and all models identified the above three risk factors. Here, we list the results of model C. Model A includes ten variables (six variables with a P value < 0.1 in univariate analysis and four variables considered clinically relevant) using forward conditional stepwise variable elimination. Model B included six variables (three risk factors in model A, American Society of Anesthesiologists physical status, the number of ARMs and the amount of loading fluids before anesthesia) using an enter method. Model C included five variables (three risk factors in model A, number of ARMs and number of prefilling fluids before anesthesia) using backward likelihood ratio stepwise variable elimination. T₂: 0.5 h after induction of pneumoperitoneum; OR: Odds ratio; CI: Confidence interval; ARM: Alveolar recruitment maneuver; PIP: Peak inspiratory pressure.