Abstract No. : ABS1071: Comparison of three different volumes of local anaesthetics in incidence of hemi-diaphragmatic paresis in ultrasound-guided interscalane brachial plexus block -A randomised controlled trial

Abstract

Background and Aims:The incidence of diaphragmatic palsy following Interscalene brachial plexus block(IBPB) is almost 100% where the drug volume plays an indispensable role. This study compared the incidence of hemi-diaphragmatic paresis and success rate following IBPB using three different volumes of local anaesthetics(LA).Methods:Ninety patients undergoing shoulder and arm surgeries under IBPB using ultrasound were randomly allocated into three groups based on volume of LA: Group A(10ml), group B(15ml), and group C(20ml). The drug administered was 0.75% ropivacaine with 50 µg dexmedetomidine under ultrasound guidance. Diaphragm excursion was measured before and 30 minutes after the block on the side of surgery. The incidence of diaphragmatic palsy and its degree were noted. The success rate following block, the onset of sensory blockade, duration of postoperative analgesia and, adverse effects were observed in all three groups.Results:The demographic data, duration of surgery and success rate following block were statistically insignificant. Hemi-diaphragmatic paresis (<25%,25-75%,>75%) in group A(29,1,0), group B(17,13,0), and group C(15,8,7) was statistically significant (P-value<0.001)(figure 1). The difference in onset of sensory blockade in group A(7.06±0.73min), group B(6.23±0.72min) and group C(4.61±0.63min) was statistically significant with a P-value<0.001. The duration of postoperative analgesia in group A(440±48.42min) group B(429±44.48min), and group C(411±51.37min), was comparable (Pvalue-0.0719). Five patients in group C developed hoarseness of voice postoperatively which was managed conservatively.Figure 1Comparison of diaphragmatic paresis in the three groupsConclusion:Lower LA volumes in ultrasound guided interscalene block is associated with lower incidence of hemi-diaphragmatic paresis with a similar success rate and duration of postoperative analgesia. Higher volume of drug yields faster onset of the sensory blockade.