Unilateral Ultrasound-Guided Transversus Abdominis Plane Block After Nephrectomy; Postoperative Pain and Use of Opioids

BACKGROUND: Pain has a wide spectrum of effects on the body and inadequately controlled postoperative pain may have harmful physiologic and psychological consequences and increase morbidity. In addition, opioid anesthetic agents in high doses can blunt endocrine and metabolic responses following surgery and are associated with side effects including dizziness, nausea, vomiting, constipation, and respiratory depression. OBJECTIVES: The current study aimed to investigate if unilateral ultrasound-guided transverse abdominal plane block (TAP-block) could reduce pain and postoperative use of patient requested analgesics following nephrectomy compared to local injection of the same ropivacaine dose in the surgical wound. PATIENTS AND METHODS: Retrospective chart reviews were performed in 42 consecutive patients who received TAP-block in conjunction with nephrectomy from November 2013 to August 2014 (group A). For comparison, data were used from 40 other nephrectomy patients registered as part of a previous study (group B). In this group the patients had received local ropivacaine injection in the surgical wound. On univariate analyses, the groups were compared by t-test and the Fisher exact test. Multivariate analyses were conducted by multiple linear regression. RESULTS: Mean surgical time was 162 minutes in group A and 92 minutes in group B (P < 0.0001). The means of visual analogue scale (VAS) were 3.05 and 1.55 in A and B groups, respectively (P = 0.001). The means of morphine consumption were 5.2 mg and 5.9 mg in groups A and B, respectively (P = 0.58); while the means of sufentanil use were 9.8 μg and 6.0 μg in groups A and B, respectively (P = 0.06). When controlling for age, tumor size and American society of anesthesiologists classification (ASA) score on multivariate analysis, TAP-block was associated with a significant increase in VAS (+1.4 [95% CI, 0.6 - 2.3], P = 0.001) and sufentanil use (+6.2 μg [95% CI, 2.3 - 10.2], P = 0.003). There was no difference in morphine use on multivariate analysis (P = 0.99). CONCLUSIONS: TAP-block in conjunction with laparoscopic nephrectomy did not reduce pain or opioid consumption. On the contrary, it seemed to prolong surgical time.