STONE DISEASE

Instillation of Skin, Nephrostomy Tract, and Renal Puncture Site with Ropivacaine Decreases Pain and Improves Ventilatory Function After Percutaneous Nephrolithotomy
Ugras MY, Toprak HI, Gunen H, Yucel A, Gunes A
Departments of Urology, Inonu University Faculty of Medicine, Malatya, Turkey
J Endourol. 2007; 21: 499-503

• 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.
  
  
• Editorial Comment
  This well-designed study sets a new standard for the evaluation of perioperative pain and respiratory function after PCNL. Visual analog pain scores and analgesic requirements were markedly less in the patients receiving instillation of local anesthesia at the conclusion of the study, and this correlated well with improvements in peak expiratory flow. However, the impact on pain scores and respiratory function wore off by 24-hours postoperative, the impact on analgesic requirements were maintained for up to 24 hours.
  The authors were meticulous in their technique. First, Ropivacaine was selected for its long half-life (8 hours) and high liposolubility (for the perirenal fat) and its low cardiac toxicity. Secondly, the authors instilled 10 cc in the renal parenchyma as the nephroscope was withdrawn, 15 cc in the nephrostomy tract alongside the nephrostomy tube and 5 cc at the skin incision.
  Previous studies have demonstrated that less opioid utilization translates into earlier control of pain, early mobilization, improved respiratory function, shorter hospital stay and lower costs. As such, instillation of local anesthesia at the completion of PCNL should be strongly considered.

Dr. Manoj Monga
Professor, Department of Urology
University of Minnesota
Edina, Minnesota, USA
E-mail: endourol@yahoo.com