Incidence of Hemidiaphragmatic Palsy After Interscalene Block

Overview

Primary objective of this study is to find out the incidence of hemi-diaphragmatic palsy associated with interscalene block done under ultrasound guidance. Primary hypothesis: • There is an incidence of hemidiaphragmatic palsy ranging fron 33-100 % after an interscalene block. Secondary hypothesis * The incidence of hemidiaphragmatic palsy is much less than 33% when the block is done using ultrasound. * The incidence of hemi-diaphragmatic palsy is directly proportional to volume of local anaesthetic injected. * The incidence of hemi-diaphragmatic palsy is directly proportional to concentration of local anaesthetic injected.

Patients of either sex belonging to American Society of Anesthesiologists status 1-3 scheduled for elective shoulder surgery as an outpatient basis, planned for an interscalene block will be included in this study over a period of one year. Potential patients will be identified from the surgeons' list. The PI or one of the co-investigators will contact them in the surgical day care in the morning of surgery and will be given information about the study. Documented informed consent will be obtained. After obtaining informed consent, they will be examined for their diaphragm position using an ultrasound prior to block placement . All patients will have the block initiated in the block room using standard monitors and sedation as per the standard practice in this hospital. The patients will undergo an ultrasound examination for their diaphragm position 5 mins and 10 mins after the completion of the nerve block. Ipsilateral ( same side as the block) and contralateral ( opposite side of block) hemi-diaphragmatic excursion will be measured with the patients in supine position during quiet inspiration ,deep inspiration and forceful sniff. In addition, bedside spirometry using a compact spirometer will be performed and FVC, FEV1 and PEFR measurements will be performed.The oxygen saturation and any evidence of dyspnea or shortness of breadth will be noted at the above mentioned intervals after the completion of the block. All patients will receive general anesthesia in the operating room. The patient will receive IV opioids during the procedure if required. The above mentioned data will be collected postoperatively in the recovery room 30 mins, after arrival.