Hysterectomy is one of the most common surgical procedures, with more than 600,000 surgeries performed in the United States each year.1 It is estimated that 30% of hysterectomies are performed using minimally invasive laparoscopic techniques.2 Although laparoscopic hysterectomy is considered a minimally invasive surgery, patients undergoing this procedure have substantial pain and may require large amounts of opioids during the first 24 hours after the procedure.3 Opioid-related side effects may impair the postoperative quality of recovery of patients undergoing laparoscopic hysterectomy.
Transversus abdominis plane infiltration consists of an injection of local anesthetic between the internal oblique abdominal muscle and the transverse abdominal muscle.4 It blocks the sensory nerve supply of the anterior–lateral abdominal wall, more precisely, the T7–12 intercostal nerves, ilioinguinal, iliohypogastric, and the lateral cutaneous branches of the dorsal rami of L1–3.5 Although transversus abdominis plane infiltration has been used successfully to reduce postoperative pain in other surgical procedures,6 the analgesic efficacy of the transverse abdominus plane infiltration after laparoscopic hysterectomy has not been described. More importantly, it is also unknown if the analgesic effect of the transversus abdominis plane infiltration would provide a better quality of postsurgical recovery in patients undergoing laparoscopic hysterectomy.
The main objective of this study was to estimate the effect of a preoperative transversus abdominis plane infiltration on postsurgical quality of recovery and analgesia of patients undergoing laparoscopic hysterectomy. A secondary objective was to estimate the dose-dependency effects of the transversus abdominis plane infiltration on postoperative analgesia and quality of recovery.
MATERIALS AND METHODS
This study was a prospective, randomized, double-blind, placebo-controlled trial. Study approval was obtained from the Northwestern University institutional review board, and written informed consent was obtained from all study participants. Eligible individuals were healthy women undergoing laparoscopic hysterectomy. Patients with a history of allergy to local anesthetics, long-term use of an opioid analgesic or corticosteroid, and pregnancy were not enrolled. Reason for exclusion from the study after study drug administration was conversion from a laparoscopic to an open procedure, because it has been shown to significantly affect early functional recovery.7 Individuals were randomized into three groups using a computer-generated table of random numbers to receive a bilateral ultrasound-guided transversus abdominis plane infiltration using saline, 0.25% ropivacaine, or 0.5% ropivacaine. Group assignments were sealed in sequentially numbered opaque envelopes that were opened by a research nurse not involved with the care of the individuals. The syringes containing 20 mL of saline, ropivacaine 0.25%, or ropivacaine 0.5% were identical and they were all labeled with study drug. The syringes were prepared by a research nurse not involved with patient care or data collection. Individuals enrolled in the study and other anesthesia care providers were also blinded to group allocation.
Patients received a standardized anesthetic regimen consisting of 0.04 mg/kg intravenous midazolam, propofol 1–2 mg/kg, and 0.6 mg/kg of rocuronium to induce muscle relaxation. Anesthesia maintenance consisted of a remifentanil infusion and sevoflurane. After anesthesia induction, a bilateral transversus abdominis plane infiltration was performed in all individuals using ultrasound guidance with a transportable ultrasound device (SonoSite) and a linear 6–13-MHz ultrasound transducer, as originally described by Hebbard et al.5 Once the external oblique abdominal, the internal oblique abdominal, and the transversus abdominal muscles were visualized using the ultrasound probe at the level of the anterior axillary line between the rib 12 and the iliac crest (Fig. 1 and video available online at http://links.lww.com/AOG/A265, or by scanning the QR Code [below] on your smartphone), the puncture area was prepared in a sterile manner. The injection of the study drug was performed using a 21-gauge 90-mm StimuQuik needle (Arrow International) by a single investigator (G.S.D.). Once the tip of the needle was placed in the space between the internal oblique abdominal muscle and the transversus abdominal muscle, and after negative aspiration of blood, 20 mL of the study drug was administered under direct ultrasonographic guidance. A contralateral infiltration was performed in the same fashion. At the end of the procedure, at removal of the laparoscopic instruments, patients received hydromorphone 10 micrograms/kg intravenously. Individuals also received intravenous ketorolac 30 mg, ondansetron 4 mg, and metoclopramide 10 mg before the end of the procedure.
In the postanesthesia recovery room, individuals were asked to rate their pain on arrival and at regular intervals on a pain numeric rating scale with possibilities of 0 to 10; 0 meant no pain and 10 was the worst pain imaginable. Hydromorphone 0.2 mg was intravenously administered every 5 minutes to maintain a numeric rating scale pain score less than 4 out of 10. The time to first hydromorphone administration was recorded. Time to meet postanesthesia care unit discharge criteria was recorded using the scoring system of White8 (score 12 or more) assessed every 15 minutes. After postanesthesia care unit discharge, patients received intravenous hydromorphone 0.2–0.4 mg for pain score more than seven (0–10 numeric rating scale) or a combination of hydrocodone 10 mg plus paracethamol 325 mg for pain score more than four but less than seven (0–10 numeric rating scale). All individuals received ibuprofen 600 mg every 6 hours for the first 24 hours.
Individuals were followed-up for 24 hours after the procedure by one of the investigators unaware of group allocation, and a validated quality of recovery questionnaire specifically designed to evaluate patients after surgery was administered.9 The questionnaire consists of 40 questions that examine five domains of patient recovery using a five-point Likert scale as follows: none of the time, some of the time, usually, most of the time, and all of the time. The five domains include physical comfort, pain, physical independence, emotions, and support. The individualized items are presented in Table 1. Perioperative data collected included age, height, weight, American Society of Anesthesiologist physical class, surgical duration, intraoperative remifentanil use, total intravenous fluids, and total amount of hydromorphone in postanesthesia care unit. Time to hospital discharge was recorded, with decision to discharge determined by the gynecologist who was also blinded to study group allocation.
The primary outcome was a QoR-40 aggregate score. Global QoR-40 scores range from 40 to 200, representing, respectively, very poor to outstanding quality of recovery. In our experience, women undergoing laparoscopic gynecologic procedures have median global QoR-40 scores of 147 at 24 hours (interquartile range 158–169). A sample size of 23 individuals per group was estimated to achieve at least 80% power at a target significance level of 0.05 (two-sided) to detect a 10-point difference in the aggregated QoR-40 score for the three study groups to be compared. These results are based on the 2000 Monte Carlo simulation assuming the median QoR-40 score for saline to be 147 and 157 for ropivacine 0.25% and 0.5%, with an estimated standard deviation of 12. A 10-point difference represents a 15% improvement in quality of recovery based on previously reported values of the mean and range of the QoR-40 score in female patients after anesthesia and surgery.9 To account for dropouts, 75 individuals were randomized. The sample size calculation was made using PASS 11.0.6.
Data were tested for skewness and kurtosis using the D'Agostino method. The Shapiro-Wilk and Anderson-Darling tests were used to test the hypothesis of normal distribution. Normally distributed interval data are reported as mean and standard deviation, and were evaluated with one-way analysis of variance (age, body mass index, surgical duration, intravenous fluids, intraoperative and postanesthesia care unit opioid consumption). Nonnormally distributed interval data and ordinal data are reported as median and interquartile range using the Kruskal-Wallis H test (postoperative pain scores, time to opioid requirement, number of postoperative antiemetics, time to meet discharge criteria from the postanesthesia care unit and discharge time from the hospital, cumulative 24 hours of opioid consumption). Post hoc comparisons were made using the Tukey-Kramer or Dunn test with correction for six comparisons. Median differences and confidence intervals for global QoR-40 scores between groups were determined using the Wilcoxon exact procedure with confidence intervals calculated at 99.17%. Categorical variables were evaluated using Fisher exact test (surgical procedures). Bivariate analyses with simple linear regression were used to detect an association between opioid consumption and global quality of recovery with the change in r2 evaluated for significance. Differences in slopes and intercepts of the linear regression lines were compared using analysis of covariance. All reported P values are two-tailed. P<.05 was required to reject the null hypothesis. Statistical analysis was performed using NCSS 2007 7.1.21 and R 2.13.0.
The details of the conduct of the study are shown in Figure 2. Seventy-five individuals were randomized and 66 completed the study. Patients were enrolled consecutively from March 2010 through October 2010. Our study population consisted of healthy women with a mean (± standard deviation) age of 47±7 years undergoing laparoscopic hysterectomy for benign disease. Patient baseline characteristics and surgical factors were not different between groups (Table 2).
The median difference (99.2% confidence interval) in global recovery scores at 24 hours after surgery was 28 (QoR-40 score 4–39, P=0.001) for ropivacaine 0.5% and 28 (QoR-40 score 10–43, P<.001) for ropivacaine 0.25% compared with saline, respectively. The median difference in global QoR-40 scores between the 0.25% ropivacaine and 0.5% groups was 0 (−8 to 18, P=.23). The dimensions of the QoR-40 questionnaire are shown in Table 3. The ropivacaine 0.5% group reported higher median scores in every dimension of the QoR-40 questionnaire compared with saline but no differences when compared with 0.25% ropivacaine. The 0.25% ropivacaine had better median scores when compared with saline in the dimensions of pain, physical comfort, and emotional status, but no difference in physical independence and support.
The 24-hour cumulative opioid consumption was lower in the 0.5% ropivacaine group when compared with the saline group (P=.003). Linear regression demonstrated an inverse relationship between opioid consumption and global quality of recovery at 24 hours for all three groups (Fig. 3). The slope of the line between opioid consumption and QoR-40 score was larger for saline compared with ropivacaine 0.5%, but it was not different between ropivacaine 0.25% and 0.5%. The numeric rating scale pain scores in the recovery room were lower for the ropivacaine groups compared with saline group (Table 4). Time to meet discharge criteria from postanesthesia recovery unit was decreased in the 0.5% ropivacaine group when compared with the saline group (P=.01, Table 4). No adverse effects or complications were reported in any of the interventional groups.
The important finding of this study is the positive effect of the transversus abdominis plane infiltration on postoperative quality of recovery in patients undergoing laparoscopic hysterectomy. This effect was present for all quality of recovery dimensions for the 0.5% ropivacaine group when compared with placebo, and it was also present for pain, physical comfort, and emotional subcomponents of the QoR-40 questionnaire for the 0.25% ropivacaine group. Individuals in the 0.5% ropivacaine group had lower pain scores and decreased opioid consumption when compared with placebo and achieved higher scores in the global QoR-40 questionnaire. Individuals in the 0.5% ropivacaine group were also able to meet discharge criteria from postanesthesia recovery unit faster than individuals in the saline group. The use of higher-dose ropivacaine (0.5%) for the transversus abdominis infiltration does not seem to provide clinically meaningful advantages on patient postoperative quality of recovery at 24 hours when compared with lower-dose (0.25%) ropivacaine after laparoscopic hysterectomy.
Beneficial effects of a transversus abdominis plane infiltration have been shown after other laparoscopic procedures. El-Dawlatly et al10 demonstrated reducing opioid consumption in patients undergoing laparoscopic cholecystectomy who received a transversus abdominis plane infiltration of local anesthetics. In colorectal resections, Conaghan et al11 demonstrated a reduction on postoperative opioid consumption without increased complications after a transversus abdominis plane infiltration. Although reduced opioid analgesic requirements have been shown after a transversus abdominis plane infiltration, previous studies have not evaluated the effect of reduced opioid consumption on quality of patient recovery after surgery. In this study, we found an inverse linear relationship between 24-hour opioid consumption and quality of recovery. The global QoR-40 scores achieved by using the transversus abdominis plane infiltration are similar to previously reported scores in outpatient laparoscopic surgery.12 These findings suggest that patients who received this technique had similar postoperative quality of recovery as patients who normally underwent outpatient surgery for other surgical procedures.
Other methods of analgesia using local anesthetics have been used to improve postoperative analgesia after laparoscopic gynecological surgery. Wound injection of local anesthetics and intraperitoneal local anesthetic instillation have been studied but have shown less consistent analgesic effectiveness after laparoscopic surgery than the transversus abdominis plane infiltration. The reported analgesic effect of intraperitoneal local anesthetics instillation for laparoscopic surgery have ranged from considerable pain reduction13 to no reduction in pain.14 Local anesthetic infiltration to the surgical wound has a short-lived (2–6 hours) duration of action and there is lack of evidence that it decreases postoperative pain.15,16 More importantly, there is also lack of evidence that these techniques can lead to a better functional recovery to patients.
It is important to note that patient recovery after hysterectomy can be affected by individual personality characteristics. Person et al17 demonstrated that women with high stress coping abilities have a better outcome in general well-being than women with low stress coping capacity. This finding is suggestive that better analgesia and reduced opioid use alone are not sole factors in quality of postoperative recovery after hysterectomy.
There are constraints to the routine use of the transversus abdominis plane infiltration of local anesthetics. The procedure requires the use of ultrasonography for accurate delivery of drug and patient safety.18 It can also be time-consuming, especially for those who are inexperienced. Although never reported, and minimized by the use of ultrasound guidance, potential serious risks with the performance of the procedure include intestinal and liver puncture. Local anesthetic toxicity is also a potential risk, but no cases have been reported so far.
There are limitations to our study. The individuals in this study were not managed as outpatients; they were discharged at the discretion of the surgeon and most were admitted overnight for observation. Therefore, we cannot determine the efficacy of use of the transversus abdominis plane infiltration in managing individuals for outpatient hysterectomy directly. We did not obtain ropivacaine blood levels to evaluate the systemic effect of the transversus abdominis plane infiltration. Because the individuals received general anesthesia, we were unable to assess the distribution of the analgesia produced by the infiltration. Finally, the study was underpowered to detect a difference in opioid consumption or global quality of recovery 40 score between the ropivacaine 0.25% and 0.5% groups.
In conclusion, we demonstrated that the preoperative transversus abdominis plane infiltration leads to a better quality of recovery and analgesia in patients undergoing laparoscopic hysterectomy. There is an association between postoperative analgesia and functional recovery of these patients. Individuals in the 0.5% ropivacaine group meet discharge criteria faster for release from postanesthesia care unit than the ones in the saline group.
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© 2011 by The American College of Obstetricians and Gynecologists.