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

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.

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 \