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

Condition(s) studied

Investigational drug(s) / intervention(s)

Alveolar Recruitment Maneuver (ARM): 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) Test: 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.

Study summary

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.

Eligibility

Primary outcome measure(s)

• Prediction of ARM-Induced Hypotension by PLR Test and PVI — From induction of general anesthesia until 5 minutes after completion of the alveolar recruitment maneuver, assessed intraoperatively.
  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).
• AUC of PVI for Predicting ARM-Induced Hypotension — Measured continuously from induction of general anesthesia until completion of the alveolar recruitment maneuver, assessed intraoperatively.
  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)

Trial sites (1)

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