Patient-controlled interscalene analgesia with ropivacaine 0.2% versus patient-controlled intravenous analgesia after major shoulder surgery - Effects on diaphragmatic and respiratory function

Background: The authors compared the effects of patient-controlled intersca lene analgesia (PCIA) with ropivacaine 0.2% and patient-controlled intraven ous analgesia (PCIVA) with opioids on hemidiaphragmatic excursion and respi ratory function after major shoulder surgery. Methods: Thirty-five patients scheduled for elective major shoulder surgery were prospectively randomized to receive either PCM or PCIVA. All patients received an interscalene block before surgery. In the PCIA group, a cathet er was introduced between the anterior and middle scalene muscles. Six hour s after the initial block, patients received for 48 h either a continuous i nfusion of 0.2% ropivacaine through the interscalene catheter at a rate of 5 ml/h plus a bolus dose of 3 or 4 mi with a lockout time of 20 min (PCIA g roup) or a continuous intravenous infusion of nicomorphine at a rate or 0.5 mg/h plus a bolus dose of 2 or 3 mg with a lockout time of 20 min (PCIVA g roup). Hemidiaphragmatic excursion and respiratory function were assessed w ith the patient in a 45 degrees semirecumbent position the day before the o peration and 20 min (in the operating room), 24 h, and 48 h after the initi al block by means of ultrasonography and spirometry, respectively. Pain rel ief was regularly assessed, side effects were noted, and patient satisfacti on was rated 6 h after the end of the study. Results: Hemidiaphragmatic excursion was similar in the two groups 20 min a fter interscalene block. Hemidiaphragmatic excursion was increased in the P CIA group on the nonoperated side 24 and 48 h after the interscalene block( P < 0.05). Pulmonary function was similar in the two groups at each time, P ain was better controlled in the PCIA group at 12 and 24 h (P < 0.05). The incidence of nausea and vomiting were 5.5% results 60% for the PCIA and PCN A groups, respectively (P < 0.05). Patient satisfaction was greater in the PCIA group (P < 0.05). Conclusions: The use of PCIA or PCIVA techniques to provide analgesia after major shoulder surgery is associated with similar effects on respiratory f unction, In the PCIA group, hemidiaphragmatic excursion showed a significan tly greater amplitude 24 and 48 h after the initial block on the nonoperate d side, The PCIA technique provided better pain control, a lower incidence of side effects, and a higher degree of patient satisfaction.