RESUMEN
BACKGROUND AND PURPOSE: Pain after percutaneous nephrolithotomy (PCNL) is well investigated, but no optimal management strategy has yet been defined. Ventilatory changes after uncomplicated PCNL remain obscure. We investigated whether pain can be managed with a combination of a parenteral non-narcotic drug and instillation of a local anesthetic into the operative field. We also measured ventilatory changes early after PCNL to determine whether this analgesic modality improves ventilatory status. PATIENTS AND METHODS: In a randomized blinded study, 34 well-matched patients underwent PCNL with single subcostal access. At the end of the operation, 30 mL of either 0.02% ropivacaine or saline was instilled into the renal puncture site, nephrostomy tract, and skin. Postoperatively, patients received parenteral metamizol (dipyrone) (500 mg/dose) on demand. Pain visual analog score (VAS), peak expiratory flow rate (PEF), and blood-gas analysis were performed at 2, 6, and 24 hours postoperatively. The number of analgesic doses required was recorded. RESULTS: The VAS at 6 hours, time to first analgesic demand, and total analgesic need were significantly lower (P=0.001, 0.008, and 0.001, respectively) in the ropivacaine group, whereas the PEF at 2 and 6 hours was significantly higher (P=0.001 for each). Analgesic use in the first 12 and 24 hours was lower in this group. Blood-gas analysis was within the normal range in both groups. Time of surgery and hemoglobin decrease were not significantly different. CONCLUSIONS: A decrease in PEF indicating restricted ventilation appears early after PCNL. Because these patients were chosen carefully to have normal function preoperatively, this decrease was attributed to nociception. A combination of ropivacaine instillation with metamizol decreases pain and analgesic use and improves PEF more than use of metamizol alone. Such a multimodal pain-management strategy is effective in minimizing postoperative opioid use with proper pain management, resulting in better ventilation.