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Effect of continuous interscalene brachial plexus block on diaphragm motion and on ventilatory function
P Pere1, M Pitkänen, P H Rosenberg
1Department of Anaesthesia, Surgical Hospital, Helsinki University Central Hospital, Finland.
Acta Anaesthesiologica Scandinavica
|January 1, 1992
Summary
Continuous interscalene block significantly impairs diaphragmatic motion and ventilatory function, leading to ipsilateral hemidiaphragm paresis in all patients. This paresis persisted in half of the patients throughout the 24-hour block.
Area of Science:
- Anesthesiology
- Pulmonology
- Thoracic Surgery
Background:
- Interscalene block is commonly used for shoulder surgery.
- Phrenic nerve block and decreased diaphragmatic motion are known complications.
- The impact of continuous interscalene block on ventilatory function requires further evaluation.
Purpose of the Study:
- To evaluate the effect of continuous interscalene block on ventilatory function.
- To assess diaphragmatic motion following continuous interscalene block.
Main Methods:
- Ten patients undergoing shoulder surgery received an interscalene block with bupivacaine, followed by a 24-hour infusion.
- Spirometry, maximal respiratory pressures, and chest radiography were performed pre-block and at multiple time points post-block.
- Hemoglobin oxygen saturation was monitored using pulse oximetry.
Main Results:
- All patients exhibited marked ipsilateral hemidiaphragm paresis 3 hours after the block.
- Reduced forced vital capacity (FVC), forced expiratory volume in 1s (FEV1), and peak expiratory flow (PEF) were observed in all patients.
- Diaphragmatic motility returned to baseline in 5 patients, but remained significantly reduced (4-37% of baseline) in the other 5 patients at 21 hours post-block.
Conclusions:
- Continuous interscalene block consistently causes ipsilateral hemidiaphragm paresis.
- Ventilatory function is significantly reduced following the block.
- Diaphragmatic paresis may persist beyond the initial 24-hour infusion period in a substantial proportion of patients.