Pulmonary function changes after interscalene brachial plexus anaesthesia; comparison between 0.75% ropivacaine and 0.5% bupivacaine

ABSTRACT

This study was carried out on 20 adult patients, scheduled for shoulder and arm surgery. After monitoring of the patients for heart rate, non invasive blood pressure and pulse oximetery. They were allocated randomely to receive 20 ml of either 0.75% ropivacaine [group I] or 0,5% bupivacaine [group II] for interscalene bradial plexus [ISBP] block. The patients demographic data were similar in both groups, the onset of sensory block and motor block were significantly prolonged in group I in comparison to group II [12.08 +/- 0.69 min and 15.05 +/- .0.69 min in group I vs 10.10 +/- 0.70 min and 12.25 +/- 0.72 min respectively] P< 0.0001. A significant reduction in pulmonary function occurred in both groups after 5 minutes till 30 minutes of the block. Forced vital capacity [FVC] decreased by 9% after 5 min to 40% after 30 minutes in group I and by 13% to 39% in group II. forced expiratory volume after one seconds [FEVl] decreased by 12% to 18% in group I and from 13.5% to 18.5% in group II. The peak expiratory flow rate [PEFR] decreased from 11% to 26.3% in group I, and from 11% to 32% after 30 minutes. No significant difference between both groups as regard FVC. FEVI, and PEFR at any time of measurement. We concluded that both 0. 75% ropivacaine and 0.5% bupivacame can be used for interscalene brachial plexus block,, but owing to the less cardiac toxicity of ropivacaine. it is recommended to be widly used