Maximum Inspiratory Pressure As A Predictor Of Post-operative Breathlessness In Obese Patients Receiving Interscalene Blocks

INTRODUCTION

•Interscalene brachial plexus block often leads to hemi-diaphragmatic

paresis due to phrenic nerve involvement.

•No current tools or devices effectively predict which patients will suffer

respiratory complications post-interscalene block.

•This study investigates if low preoperative Maximum Inspiratory

Pressure (MIP) correlates with increased risk of postoperative

breathlessness in obese patients receiving interscalene blocks.

METHODS

•The study, approved by the institutional ethics board, enrolled 45

patients across 3 groups based on BMI and surgical approach, focusing

on the effects of interscalene block and general anesthesia.

Standard anesthesia protocols were applied, ensuring no deviation from

care standards.

•Respiratory metrics, including MIP and spirometry values, were

collected pre- and post-operation using standardized equipment and

methods. Breathlessness was assessed using modified Borg

questionnaire.

RESULTS

•Demographic similarities were observed across groups, with significant

differences in weight, BMI, and cardiovascular disease incidence,

particularly between groups 1 and 2.

•A significant relationship between low preoperative MIP and

postoperative breathlessness was identified in obese patients.

•Obese patients with lower MIP had lower PACU SaO2 despite extended

oxygen support and had longer PACU stays.

•Spirometry lung volume measurements did not predict breathlessness.

Percent predicted FEV1 showed mild correlation.

DISCUSSION

•This study identifies low preoperative MIP as a predictive

measure for postoperative breathlessness in obese patients

undergoing interscalene nerve block.

•This is a groundbreaking novel application of MIP

measurement in regional anesthesia, highlighting its potential

in improving preoperative assessments and patient outcomes.

•It underscores the unique respiratory challenges in obese

patients, suggesting pathophysiological differences that

necessitate tailored anesthesia approaches.

•The findings advocate for further research to refine MIP cutoff

values for better predicting respiratory complications, aiming to

enhance safety and efficacy in anesthetic practice for high-risk

patient groups.