Paravertebral Block for Percutaneous Nephrolithotomy: A Prospective, Randomized, Double-Blind Placebo-Controlled Study
Kristin G. Baldea, Grace Delos Santos, Chandy Ellimoottil, Ahmer Farooq, Elizabeth R. Mueller, Thomas M.T. Turk, Scott Byram
Loyola University Medical Center, Maywood, IL
Percutaneous nephrolithotomy (PCNL) is considered the gold standard minimally invasive treatment for large stone burdens, but post-operative pain control remains challenging. Paravertebral block (PVB) has been described for breast and thoracic surgery as an effective pain control strategy, but is not commonly utilized for PCNL. The objective of this study was to evaluate the effect of paravertebral block on pain control and opioid use following PCNL.
This was a prospective, randomized, double-blind, placebo-controlled study. Forty-five patients undergoing unilateral PCNL for stone disease were consented and randomized to receive either PVB or placebo intervention in the preoperative area. Patients were placed in the sitting position sedated with midazolam prior to the block procedure. The ultrasound guided PVB was performed with of a single injection of 20 mL of 0.5% bupivacaine with epinephrine 1:200,000 into the T10 paravertebral space. A 2-6 MHz curvilinear probe was used. For the placebo intervention, the paravertebral space was imaged with the ultrasound, the skin is infiltrated with lidocaine, and pressure held to mimic injection. All blocks were performed by one of the acute pain service faculty members that specialize in regional anesthesia. Following the block or sham injection, the patients were transferred to the operating room and a standardized general anesthetic was administered. The patient, surgeon, and anesthesia team were blinded to the study group. All patients received a patient-controlled analgesia (PCA) following surgery. Outcomes examined were: visual analog scale (VAS) pain scores, intra-operative and post-operative opioid use, and anti-emetic use. Statistical analysis was performed using paired t-tests for continuous variables and chi-square tests for categorical variables.
The 45 patients enrolled in the study had no difference in baseline characteristics. There were no complications attributed to the PVB. The average VAS pain score was lower in the PVB group (2.78 vs. 3.48 p = 0.03). Intra-operative opioid use, post-operative opioid use, frequency of opioid use, and anti-emetic use were significantly lower in the PVB group as compared to the control group. The time from the conclusion of surgery to the first administration of opioids was longer in the PVB group. Although the power analysis called for twice the number of patients, the study was terminated early due to the significant results.
To our knowledge, this is the first randomized, double-blind, placebo-controlled trial investigating the use of PVB in PCNL. PVB prior to PCNL improved average VAS pain scores and decreased both intra-operative and post-operative opioid use. The reduction in opioid use likely leads to improved nausea as reflected in decreased anti-emetic use. PVB should be considered an effective strategy to reduce pain for patients undergoing PCNL.