Alveolar Recruitment Maneuver-Induced Hypotension: A Dynamic Consequence and Intraoperative Indicator of Fluid Responsiveness

N/ANot Yet RecruitingNCT07766967

University of Health Sciences Balikesir Hospital Eduation and Research70 enrolled

Overview

This study investigates whether two simple bedside tests - the Passive Leg Raising (PLR) test and the Pleth Variability Index (PVI) - can predict a drop in blood pressure that sometimes occurs during a lung-opening procedure called an Alveolar Recruitment Maneuver (ARM). ARM is routinely performed during general anesthesia to prevent lung collapse and improve oxygen levels. However, in some patients - particularly those with low fluid levels - ARM can cause a temporary but significant drop in blood pressure (hypotension), which may require immediate treatment. In this prospective observational study, adult patients scheduled for elective non-cardiac, non-thoracic surgery under general anesthesia will be enrolled. Before each ARM is performed, PLR test and PVI values will be measured. We will then evaluate how well these measurements predict whether the patient will develop ARM-induced hypotension. If PLR and PVI can reliably identify patients at risk, clinicians may be able to take preventive steps before performing ARM, making the procedure safer for vulnerable patients.

Study Type

INTERVENTIONAL

Allocation

Purpose

DIAGNOSTIC

Masking

NONE

Enrollment

Conditions

Hypotension Drug-Induced General Anesthesia Using Endotracheal Intubation

Interventions

Alveolar Recruitment Maneuver (ARM)DEVICE

ARM is performed using a stepwise increase in positive end-expiratory pressure (PEEP) in pressure-controlled ventilation mode until peak inspiratory pressure reaches 40 cmH₂O, then stepwise decrease back to baseline. Hemodynamic parameters are continuously monitored throughout the maneuver.

Passive Leg Raising (PLR) TestBEHAVIORAL

With the patient in supine position under general anesthesia, both legs are raised to 45 degrees for 60 seconds. The change in mean arterial pressure (ΔMAP) is recorded as an indicator of preload responsiveness. The test is performed immediately before each ARM.

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion Criteria:Age 18 years or older ASA physical status I or II Scheduled for elective non-cardiac, non-thoracic surgery under general anesthesia Able to provide written informed consent - Exclusion Criteria:Cardiac or thoracic surgery Hemodynamic instability at baseline (MAP \<65 mmHg or requirement for vasopressors) Severe valvular heart disease or known cardiac dysfunction (EF \<40%) Chronic obstructive pulmonary disease (COPD) or severe respiratory disease Atrial fibrillation or other significant arrhythmias Peripheral vascular disease affecting PVI signal quality Body mass index (BMI) \>40 kg/m² Emergency surgery Refusal to participate or inability to provide informed consent Pregnancy \-

Outcomes

Primary Outcomes

Prediction of ARM-Induced Hypotension by PLR Test and PVI

Area under the ROC curve (AUC) of pre-ARM passive leg raising test (PLR-ΔMAP) for predicting ARM-induced hypotension (defined as MAP decrease ≥20% from baseline or MAP \<65 mmHg during ARM).

Time frame: From induction of general anesthesia until 5 minutes after completion of the alveolar recruitment maneuver, assessed intraoperatively.

AUC of PVI for Predicting ARM-Induced Hypotension

Area under the ROC curve (AUC) of pre-ARM pleth variability index (PVI) for predicting ARM-induced hypotension (defined as MAP decrease ≥20% from baseline or MAP \<65 mmHg during ARM)

Time frame: Measured continuously from induction of general anesthesia until completion of the alveolar recruitment maneuver, assessed intraoperatively.

Secondary Outcomes

Correlation Between ARM-Induced ΔMAP% and Post-ARM Fluid Responsiveness

Pearson or Spearman correlation coefficient between the maximum MAP decrease during ARM (ΔMAP%) and fluid responsiveness after ARM. Fluid responsiveness is defined as MAP increase ≥10% following 250 mL crystalloid bolus.

Time frame: From onset of ARM until 10 minutes after completion of ARM, assessed intraoperatively.

Comparative Diagnostic Accuracy of PLR Test versus PVI for Predicting ARM-Induced Hypotension

The difference in AUC values between PLR-ΔMAP and PVI will be compared using the DeLong method.