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REGIONAL ANESTHESIA

A Prospective Comparison of Continuous Wound Infiltration with Ropivacaine Versus Single-Injection Paravertebral Block After Modified Radical Mastectomy

Tatiana Sidiropoulou, MD^*, Oreste Buonomo, MD, Eleonora Fabbi, MD, Maria Beatrice Silvi, MD, Georgia Kostopanagiotou, MD^*, Alessandro Fabrizio Sabato, MD, and Mario Dauri, MD

From the *Second Department of Anesthesiology, University of Athens, Attikon Hospital, Athens, Greece; Thoracic Surgery Division, Tor Vergata University, Rome, Italy; and Department of Anesthesiology and Intensive Care, Tor Vergata University, Rome, Italy.

Address correspondence and reprint requests to Tatiana Sidiropoulou, MD, Dolasik 18 P. Psihico, 15452 Athens, Greece. Address e-mail to tatianasid{at}gmail.com.

	Abstract

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BACKGROUND: The efficacy of continuous wound infiltration with local anesthetic has not been compared with that of thoracic paravertebral block (PVB) after breast surgery. In this study, we evaluated the analgesic efficacy and morphine consumption of the two techniques after mastectomy.

METHODS: Forty-eight patients undergoing modified radical mastectomy with axillary dissection were randomly assigned to either a preoperative PVB with 20 mL of ropivacaine 0.5% (group PVB) or a continuous ropivacaine 0.5% infusion (CRI) at a 2 mL/h rate for each of two multilumen catheters placed subcutaneously at the end of the procedure (group CRI). The catheters were left in place for 24 h postoperatively. A standardized general anesthetic was administered to all patients. Postoperative morphine consumption, pain scores and painful restricted movement of the shoulder for 24 h postoperatively as well as incidence of adverse events, including postoperative nausea and vomiting, were recorded.

RESULTS: Morphine consumption was similar between groups (PVB: 42.6 ± 11 vs CRI: 38.7 ± 11 mg in 24 h, P = 0.225). Absolute pain scores were low in both groups. Four hours after surgery, group PVB showed a significant reduction in postoperative pain (PVB: 0 [0–10] vs CRI: 0 [0–30], P = 0.002) and reduced painful restricted movement (P = 0.004), whereas the CRI group had lower pain scores (PVB: 10 [0–30] vs CRI: 0 [0–20], P = 0.034) and painful restricted movement (P = 0.043) 16 and 24 h (PVB: 10 [0–30] vs CRI: 0 [0–30], P = 0.012) after surgery. Postoperative nausea and vomiting was significantly more frequent in the CRI group (P = 0.017).

CONCLUSIONS: Continuous wound infiltration of local anesthetics is an effective alternative to paravertebral analgesia after mastectomy with axillary dissection.

	Introduction

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Pain after mastectomy is variable, and restriction in movement of the shoulder is frequently observed.1 A variety of local and regional techniques, including local anesthetic infiltration,2–9 intercostal block,10 paravertebral block (PVB),11–17 and thoracic epidural anesthesia,18 have been introduced with the goal of reducing the side effects associated with general anesthesia and IV opioid analgesia. For example, thoracic PVB has been shown to effectively reduce postoperative pain and the incidence of postoperative nausea and vomiting (PONV).12,16 This technique however, as well as thoracic epidural anesthesia, is associated with the risk of pneumothorax, pleural puncture, and intravascular injection. Conversely, local anesthetic infiltration may avoid some of the difficulties associated with the above-mentioned techniques and still provide superior analgesia and fewer side effects to a standard opiate-based postoperative analgesia.5–9 Although local anesthetic infiltration has indisputable benefits in postoperative pain relief in other clinical settings,19–21 its efficacy in patients undergoing breast surgery remains controversial.2–9 Several authors report a reduction in IV analgesic requirement and postoperative pain relief after local anesthetic infiltration pre-9 or postoperatively,5–8 while other trials failed to show any benefit from pre-3 or postoperative4 wound infiltration of local anesthetic. The aim of our study was to compare the effects of paravertebral analgesia to continuous wound infusion of local anesthetic with respect to morphine consumption (our primary outcome variable), postoperative pain relief, movement restriction, and PONV.

	METHODS

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The study was approved by the Institutional Ethics Committee and written informed consent was obtained from all patients. The study was performed at the Policlinico "Tor Vergata" in Rome, Italy. Fifty adult women, ASA physical status class I–III, scheduled for unilateral modified radical mastectomy with axillary dissection were consecutively enrolled. Axillary dissection included levels I–II. No "en bloc" dissection was performed; instead, lymph nodes and fat were sampled with the aim of preserving as much of the inter-costobrachial nerves, blood, and lymph vessels as possible. Exclusion criteria included patients unable to cooperate, with a known allergy to ropivacaine or morphine, with bleeding disorders, receiving anticoagulants, suffering from significant liver or renal disease or diabetes, with a history of drug or alcohol abuse, suffering from chronic pain or regularly receiving analgesics or corticosteroids.

Before surgery, patients were randomly allocated by a computer-generated list of random numbers and sealed envelopes to two groups. One group received a single-injection ipsilateral PVB preoperatively, while the other group had a postoperative continuous wound infiltration of ropivacaine 0.5% via two multilumen catheters connected to an elastomeric balloon pump (group CRI). All patients were given midazolam 1–2 mg IV before anesthesia. Monitoring included electrocardiography, pulse oximetry, end-tidal CO₂, noninvasive arterial blood pressure and Bispectral Index (BIS 2000 Monitor, Aspect Medical Systems, Newton). General anesthesia was induced with 0.3–0.5 mcg/kg sufentanil and propofol target-controlled infusion 3–5 mcg/mL (depending on the patient's age and physical condition). Tracheal intubation was facilitated with rocuronium 0.5–0.8 mg/kg. Anesthesia was maintained with propofol infusion and an oxygen/air mix with a fraction of inspired oxygen of 40%. Bispectral Index values were maintained between 40 and 60. Sufentanil 5–10 mcg in bolus doses was given IV wherever mean arterial blood pressure or heart rate exceeded 20% of preoperative baseline values. Hypotension, defined as mean arterial blood pressure <20% from baseline, was treated with ephedrine 5–10 mg IV as needed. All patients were treated with ondansetron 4 mg IV, 30 min before the end of the procedure, to prevent PONV.

After emerging from anesthesia, the patients were transferred to the postanesthesia care unit for a 2-h observation period. Analgesia was provided with patient-controlled analgesia with morphine 1 mg/mL set at boluses of 1 mg each with a lockout period of 5 min. Maximum morphine consumption at 4 h was set at 16 mg.

Local Anesthetic Protocols
PVB
Before induction of general anesthesia, patients were turned in the lateral position with the side to be blocked and operated on upward. A 25-gauge needle was inserted 2.5 cm lateral from the cephalad edge of the third thoracic vertebral spinal process, and the skin, subcutaneous tissue, and periosteum of the transverse process were anesthetized with 5 mL of lidocaine 2%. The PVB was performed with an 18-gauge Tuohy needle and the loss-of-resistance technique according to Eason and Wyatt,22 seeking contact with the transverse process of the fourth thoracic vertebra as a landmark before advancing the needle into the paravertebral space. Twenty milliliters of ropivacaine 0.5% was injected into the paravertebral space in four or five aliquots with repeated aspiration tests. Ten to 15 minutes after block placement, decreased temperature sensation in the T1–5 dermatomes was defined as a successful block.

CRI
Before wound closure, a 20-gauge multiorifice catheter was placed in a loop over the pectoralis major muscle and a second 20-gauge multiorifice catheter was placed in the axillary dissection area subcutaneously (OnQ Pain Buster, I-Flow Corporation, CA). Each catheter has a distribution length for local anesthetics of 6.5 cm. The catheters were then taped to the skin and covered. The two catheters were connected via a Y-connector to an elastomeric balloon pump. The pump delivered ropivacaine 0.5% at a 2 mL/h rate for each catheter. The infusion was started immediately. The infusor set was physically small and covered securely by clothing; thus the assessor evaluating pain scores and morphine consumption would not be able to see it.

Data Collection
Postoperative analgesia data were collected using a visual analog scale (VAS) (0–100 mm) as well as painful restricted movement of the shoulder, classified into three grades (restricted, fair, and free) every 4 h starting from the arrival of the patient in the postanesthesia care unit and lasting throughout the 24-h study period. Painful restricted movement was assessed as external and internal rotation as well as abduction of the arm and scores were as follows: all 3 modalities present = free, 2 modalities present = fair, 1 or 0 modality present = restricted. Nausea lasting more than 10 min or vomiting was treated with 4 mg ondansetron. Morphine consumption as well as administration of antiemetic medication and incidence of adverse effects (nausea, vomiting, pruritus, sedation, headache, hypotension) were recorded. Patients were asked to rate their satisfaction with the regimen of analgesia used (1 = insufficient, 2 = sufficient, 3 = good, 4 = excellent). Data were collected by an unbiased observer who was not otherwise involved in the study. Patients were monitored throughout their hospital stay for complications related to PVB (epidural involvement, pneumothorax, etc.) and for signs of local anesthetic toxicity.

Statistical Analysis
The sample size was based on an estimated 24-h postoperative morphine consumption (our primary outcome variable) of 40 mg (SD 10 mg) and a belief that a 25% (10 mg) reduction in morphine consumption would be clinically significant. Given a type I error of 0.05 and a power of 90%, we estimated that the required sample size would be 22 patients per group. We enrolled 50 patients to allow for dropouts.

Statistical analyses were performed with SPSS 9.0 for Windows (SPSS, Chicago, IL). Results in text and tables are expressed as mean ± sd or median (range) as appropriate. Normally distributed data were analyzed using the Student's t-test or analysis of variance for repeated measurements with the Bonferroni correction, whereas for analysis of categorical and skewed data Mann–Whitney U-test, ² test, or Kruskal–Wallis test was used as appropriate. A value of P < 0.05 was considered statistically significant.

	RESULTS

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Forty-eight patients completed the study (PVB = 24, CRI = 24). Two patients, one from each group, were excluded from the study. One patient was excluded from the PVB group because of altered surgical procedure and a patient from the CRI group was excluded due to catheter dislocation during patient recovery. These two patients were not included in statistical analysis.

There were no significant differences between the two groups with respect to age, weight, height, ASA classification, and length of anesthesia or surgery (Table 1). Intraoperative propofol and sufentanil consumption were similar in both groups (Table 1). All patients in the PVB group had decreased temperature sensation to at least four dermatomes and thus we considered all PVBs as successful. No accidental pleural puncture or bilateral spread of the anesthetic was observed. Surgery was uneventful in all cases. Intraoperative hemodynamic fluctuations were nonsignificant (<20% from baseline). Baseline values of VAS and painful restricted movement were equal between groups. There was no difference in morphine consumption throughout our observation period. Patients belonging in the PVB group had lower VAS scores and less restriction in the movement of the shoulder in the early postoperative period (4 h), while later (16, and 24 h) the CRI group had significantly lower VAS scores and less disability with respect to the PVB group (Table 2).

Vomiting and overall incidence of PONV were significantly more frequent in the CRI group (Table 3). Administration of ondasetron did not differ significantly between the two groups (PVB: 12% vs CRI: 29%, P = 0.2708). Patient satisfaction did not differ significantly between groups (Fig. 1). Although patients were not examined with chest radiographs postoperatively, there were no clinical signs of pneumothorax or local anesthetic toxicity during our 24-h observation period.

View larger version (12K): [in this window] [in a new window]   Figure 1. Patient satisfaction rate for analgesia after mastectomy. PVB = paravertebral block; CRI = continuous ropivacaine infusion.

	DISCUSSION

Top Abstract Introduction METHODS RESULTS DISCUSSION REFERENCES

 
In this prospective randomized study, the pain management of all women undergoing radical mastectomy with axillary dissection was satisfactory and the absolute pain scores were low. Although total morphine consumption did not differ between the two groups, our study was designed to detect differences in 24-h morphine consumption more than 10 mg, which would be clinically relevant. A larger sample size would be needed to detect smaller differences.

Many investigators consider PVB to be the technique of choice for pain relief after mastectomy.11–17 Single14–16 versus multiple11,12 injection techniques have been described but the superiority of one technique over the other for breast surgery has not been evaluated. According to our study, the most important analgesic effect of the PVB was observed in the early postoperative period when patients belonging to the PVB group showed lower VAS scores and significantly better mobility of the arm with respect to the CRI group.

On the other hand, wound instillation of local anesthetics and field blocks are very common after breast surgery,2–9 although not always effective.2–4 In our study, patients experienced less pain when the CRI was well established, 16 h after surgery. At that time-point, the analgesic effect of the PVB was most likely resolving in the other group. The differences observed in pain scores at 4, 16, and 24 h are clinically insignificant because all median scores were low.23 Thus, no clear benefit of one technique over the other regarding postoperative analgesia was observed in this trial, although it should be noted that the continuous wound infiltration requires no skill and therefore might constitute a superior technique.

The incidence of PONV in our patients was relatively low, considering that the general risk of PONV in women undergoing breast surgery under general anesthesia is high.24,25 The extent to which the use of propofol reduced the occurrence of PONV25 remains speculative. Intraoperative sufentanil administration, another possible cause of PONV, was also similar in both groups. In any case, the patients undergoing PVB experienced less PONV.

Our study evaluated only single-injection, rather than continuous PVB. If a continuous PVB had been performed, postoperative analgesia would have been prolonged, and thus pain scores, morphine consumption and mobility may have been affected. However, the effects of a single-injection PVB with long-acting local anesthetics is expected to last at least 12 h after surgery14 with other authors reporting an analgesic effect averaging 23 h (range, 9–38 h).13 Likewise, the performance of the PVB preoperatively may have provided a preemptive effect. We shared this concern when designing the study. However, we could not have performed the PVBs at the end of surgery as it is not regular practice in our institution to perform anesthesia/analgesia techniques in anesthetized patients. Moreover, waiting for the patients’ full recovery in order to be able to communicate with them, and thus perform the PVBs safely, would have caused a delay in initiating the postoperative analgesia treatment and resulted in greater discomfort to patients.

In conclusion, continuous wound infiltration of local anesthetics is an effective alternative to paravertebral analgesia after mastectomy with axillary dissection. Both techniques were associated with low pain scores and reduced limitation of movement postoperatively. PONV was less frequent in patients who received a thoracic PVB.

	Footnotes

 
Accepted for publication November 1, 2007.

	REFERENCES

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Sidiropoulou, T. Articles by Dauri, M. Search for Related Content PubMed PubMed Citation Articles by Sidiropoulou, T. Articles by Dauri, M. Related Collections Anesthetic Techniques Regional Anesthesia Pharmacology