How Accurate Is Non-Invasive Blood Pressure Monitoring During Trendelenburg Laparoscopic Surgery?

This is a prospective observational study designed to evaluate the clinical accuracy and reliability of non-invasive blood pressure (NIBP) monitoring in adult patients undergoing laparoscopic surgery in the Trendelenburg position. The accuracy of NIBP will be assessed by comparing it to invasive arterial blood pressure (IABP), which is considered the reference standard. The comparison will be performed using error grid analysis, a method that not only quantifies measurement differences but also categorizes the clinical risk of those discrepancies.

The Trendelenburg position, characterized by a head-down tilt of the patient, is frequently employed during gynecological and urological laparoscopic procedures to enhance surgical exposure. However, this positioning alters hemodynamic physiology and may influence peripheral blood pressure measurements. Previous evaluations of NIBP in this context have primarily relied on Bland-Altman analysis, which measures statistical agreement but does not assess the potential clinical consequences of disagreement between methods.

Error grid analysis overcomes this limitation by mapping paired NIBP and IABP values into predefined risk zones (A-E), based on their potential to affect clinical decision-making. Zone A reflects acceptable agreement with no risk of incorrect treatment, whereas Zones B through E indicate increasing levels of clinical risk.

In this study, NIBP and IABP will be measured simultaneously every 20 minutes throughout the procedure. The proportion of measurements falling within each error grid zone will be calculated. If fewer than 90% of the paired measurements fall within Zone A, NIBP will be considered insufficiently reliable for use in this surgical context without concurrent invasive monitoring.

A pilot study of five patients was conducted to estimate the intracluster correlation coefficient and design effect, which informed the final sample size calculation. Based on these preliminary data, a total of 100 patients is estimated to provide adequate statistical power to evaluate the primary outcome with 95% confidence and a 5% margin of error.

The study will also document intraoperative variables that may affect blood pressure measurement accuracy, including the use of vasoactive infusions. These data may provide insight into subgroups where NIBP reliability is particularly limited or acceptable.

The findings of this study may inform future monitoring protocols and could reduce unnecessary use of invasive lines in appropriately selected patients, improving patient safety and comfort while maintaining clinical accuracy.

• Distribution of Paired Systolic Blood Pressure Measurements Across All Error Grid Zones (A-E) [Срок оценки: Intraoperative period (measurements taken every 20 minutes during surgery)]
• Distribution of Paired Mean Arterial Pressure (MAP) Measurements Across All Error Grid Zones (A-E) [Срок оценки: Intraoperative period (measurements taken every 20 minutes during surgery)]
• Effect of Antihypertensive Medication Use on the Accuracy of Systolic NIBP Measurements [Срок оценки: Intraoperative period (measurements taken every 20 minutes during surgery)]
• Effect of Antihypertensive Medication Use on the Accuracy of Mean Arterial Pressure (MAP) NIBP Measurements [Срок оценки: Intraoperative period (measurements taken every 20 minutes during surgery)]