Subcutaneous infiltration and
wound lavage with
ropivacaine is an alternative to
opioids after major shoulder surgery. However, the efficacy and potential toxicity of this method remain unclear. We therefore evaluated plasma
ropivacaine concentrations after shoulder infiltration and
wound lavage. We subsequently quantified the efficacy of two
ropivacaine concentrations. Patients undergoing major shoulder surgery were anesthetized with
alfentanil and
propofol. The initial patients (n = 18) received
ropivacaine 7.5 mg/mL and
ropivacaine plasma concentrations were measured in 15-min intervals. The subsequent 45 patients were randomly assigned to: 1) isotonic saline, 2) 3.75 mg/mL
ropivacaine, or 3) 7.5 mg/mL
ropivacaine. Ten milliliters of each
solution was administered subcutaneously and 20 mL was injected into the
wound drain which was clamped for 10 min. Supplemental
postoperative pain relief was provided by patient-controlled
anesthesia using the
opioid piritramid (3.5-mg boluses, 6-min lock-out).
Postoperative pain scores were recorded on a 100-mm visual analog scale for 4 h in the initial patients and for 10 h in the second part of the study. Unbound
ropivacaine plasma concentrations peaked after 15 min at 0.08+/-0.09 microg/mL; the maximum was 0.30 microg/mL, compared with a toxic threshold of 0.6 microg/mL. In the second part of the study,
pain scores were significantly lower after 3.75 mg/mL (20+/-15 mm) or 7.5 mg/mL (10+/-9 mm)
ropivacaine than saline (35+/-10 mm).
Piritramid requirements differed significantly in the three groups, being highest with saline and lowest with
ropivacaine 7.5 mg/mL. We conclude that
wound infiltration and lavage with 30 mL
ropivacaine 7.5 mg/mL after major shoulder surgery resulted in very low
pain scores and
opioid requirement.
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