Anesth Analg 2008; 107:665-668
© 2008 International Anesthesia Research Society
doi: 10.1213/ane.0b013e31817b7f01
ANALGESIA
The Feasibility of Patient-Controlled Paravertebral Analgesia for Major Breast Cancer Surgery: A Prospective, Randomized, Double-Blind Comparison of Two Regimens
Jennifer McElwain, FCARCSI*,
Noelle M. Freir, FCARCSI*,
Crina L. Burlacu, FCARCSI*,
Denis C. Moriarty, FCARCSI*,
Daniel I. Sessler, MD , and
Donal J. Buggy, MD, MSc, DME, FRCPI, FCARCSI, FRCA*
From the *Department of Anaesthesia, Mater Misericordiae University Hospital, Dublin, Ireland; Department of Outcomes Research, The Cleveland Clinic, Cleveland, Ohio; National Cancer Screening Service, Eccles Unit, Dublin, Ireland.
Address correspondence and reprint requests to D. J. Buggy, Department of Anaesthesia, Mater Misericordiae University Hospital, Eccles St, Dublin 7, Ireland. Address e-mail to donal.buggy{at}nbsp.ie or www.or.org.
Abstract
BACKGROUND: Paravertebral analgesia is useful for breast surgery. Patient controlled analgesia by IV or epidural routes is well established for delivering postoperative analgesia. Our objective was to apply patient control to paravertebral analgesia and evaluate the efficacy and tolerability of two distinct dosing regimens.
METHODS: Patients undergoing major breast cancer surgery were recruited for this prospective, double-blind, randomized trial of two patient-controlled paravertebral analgesia regimens: 19 patients received levobupivacaine 0.2% at 8 mL/h with 3-mL bolus and 15-min lockout (15-min lockout group); 18 received levobupivacaine 0.2% at 4 mL/h with 8-mL bolus and 30-min lockout (30-min lockout group). Our primary outcome was dynamic pain scores (visual analog scale) at 4-hourly intervals for 36 h. Secondary outcomes were resting pain scores, rescue analgesia requirements, volume of levobupivacaine administered, demands for levobupivacaine, levobupivacaine boluses received, and patient satisfaction.
RESULTS: Resting and dynamic pain scores were comparable in the groups. Two 15-min lockout patients and five 30-min lockout patients required rescue analgesia (P = 0.23). Patients received 400 ± 95 mL and 330 ± 130 mL levobupivacaine in 15-min and 30-min lockout groups, respectively (P = 0.012). The 15-min lockout group requested a bolus 75 ± 16 times; the 30-min lockout group requested it 69 ± 14 times (P = 0.40). However, the 15-min lockout group received 39 ± 22 boluses and the 30-min lockout group only 24 ± 16 (P = 0.02). Systolic pressure, heart rate, respiratory rate, sedation scores, nausea, antiemetic requirement, and satisfaction scores were similar in each group.
CONCLUSIONS: Patient-controlled paravertebral analgesia for breast cancer surgery, with either regimen, provided satisfactory analgesia and was well tolerated.
Postoperative pain continues to be under-treated.1 Patient-controlled IV analgesia with opioids remains a common strategy for management of postoperative pain2; however, this method is far from ideal because efficacy is suboptimal and side effects frequent.3,4 Regional anesthetic techniques, particularly epidural analgesia, offer better quality analgesia and fewer side effects than IV opioids.5,6 In a meta-analysis, for example, epidural analgesia, regardless of analgesic drug, regimen, or type or time of pain assessment, provided superior postoperative analgesia compared with patient-controlled IV analgesia.7
Paravertebral analgesia is a useful technique in patients requiring breast surgery and has been used as the sole anesthetic8,9 and for ambulatory surgery.10 It is well established that paravertebral blocks provide better postoperative analgesia than general anesthesia followed by IV or IM opiates,8,9,11 reduce the risk of nausea and vomiting,8,9,11 and shorten hospitalization.9 When compared with postoperative opiates, continuous paravertebral infusions of local anesthetic improve subcutaneous tissue oxygenation,12 thus possibly reducing infection risk and improving wound healing. Furthermore, the introduction of patient-controlled epidural analgesia (PCEA) during labor reduced the total dose of local anesthetic administered and gave patients a sense of control over their analgesia.13
Applying the principles of patient-controlled analgesia (PCA) to paravertebral analgesia has yet to be described. We therefore evaluated the feasibility of patient-controlled paravertebral analgesia (PCPA) in patients recovering from breast cancer surgery. The closest clinical and anatomical analogy to a PCPA infusion is a PCEA infusion. PCEA regimens tend to have either a small bolus with short lockout period or a large bolus with a long lockout period because the optimum regimen remains unclear.13,14
The two PCPA regimens were developed at our institution based on our experience with paravertebral infusions. One regimen had a large bolus, long lockout (30-min group) and the other a small bolus with a short lockout (15-min group), thus ensuring that the total amount of levobupivacaine available to each patient was equal. Our hypothesis was that there would be a difference in primary outcome (i.e., pain score) between a short lockout and a long lockout postoperative PCPA regimen.
METHODS
With Ethics Committee approval and written, informed patient consent, we enrolled 38 patients undergoing major breast cancer surgery. Patients were age 18 yr or older and ASA physical status I or II. Exclusion criteria were allergy to study medications and any contraindication to paravertebral catheter insertion, including local infection and coagulopathy.
Protocol
Before induction of general anesthesia, a paravertebral catheter was inserted ipsilateral to the surgical site at the level of the second or third thoracic vertebrae. General anesthesia was induced and a 20 mL bolus of levobupivacaine 0.25% was injected through the paravertebral catheter before skin incision. An additional 10 mL was given at skin closure. Adjuvant analgesia (paracetamol 1 g IV, diclofenac 75 mg IV) and ondansetron 4 mg IV were also given. Supplemental morphine (0.15 mg/kg in total) was given at the discretion of the attending anesthesiologist. Indications for supplemental morphine were a 20% increase from baseline in heart rate, respiratory rate (if spontaneously breathing), and arterial blood pressure.
Patients were assigned to one of two postoperative analgesic regimens based on computer-generated randomizations
- 15-min lockout: Paravertebral levobupivacaine 0.2% 8 mL/h as a continuous infusion. Patient demand bolus dose: 3 mL, lockout time was 15 min.
- 30-min lockout: Paravertebral levobupivacaine 0.2% 4 mL/h as a continuous infusion. Patient demand bolus dose: 8 mL, lockout time was 30 min.
Postoperative adjunctive analgesia was prescribed (oral paracetamol, 1 g 4-times daily, and oral diclofenac, 75 mg once daily). Rescue analgesia (given if a pain score exceeded 40 mm on visual analog scale [VAS]) was 0.15 mg/kg morphine, IM, with a maximum daily dose of 0.9 mg/kg. Postoperative nausea or vomiting was treated with ondansetron 4 mg 8 hourly PRN.
Measurements
Patients reported pain scores on a 100-mm-long VAS (0 mm = no pain, 100 mm = worst possible pain) at rest and on movement (90 degrees arm abduction) every 4 h while awake for 36 postoperative hours. Investigators unaware of group allocation (NF, JMcE) collected the pain scores.
The number of bolus demands, the actual number of boluses received, and total volume used were recorded. The primary outcome measure was VAS pain score with movement. Secondary outcome measures were pain scores at rest, rescue analgesic requirements, the total volume of levobupivacaine administered, number of patient-controlled demands made, and number of bolus doses received.
Hemodynamic variables, incidence of nausea and vomiting, requirement for antiemetic medication, complications, and sedation scores were recorded. Patient satisfaction was recorded on a 100-mm VAS (0 mm = completely dissatisfied, 100 mm = completely satisfied) after catheter removal.
Statistical Analysis
We considered a 15-mm reduction in the dynamic VAS pain score as being clinically important. With the knowledge that the standard deviation of dynamic VAS scores for postoperative PCEA is approximately 13 mm,10 we estimated that 16 patients would provide a 90% power to detect a true difference between the two regimens with an  error = 0.05. We enrolled 38 patients (19 in each group) to compensate for potential exclusions or protocol deviations.
Parametric data were compared using ANOVA with post hoc Bonferroni correction. Categorical data were compared using  2 analysis of contingency tables. Results are presented as means ± sds or number of patients (percent); P < 0.05 defined statistically significant differences.
RESULTS
Thirty-seven women were included in the study: 19 in the 15-min lockout group and 18 in the 30-min lockout group. Data from one patient (30-min lockout group) were lost because of inadvertent failure to follow-up reporting. Three patients had the paravertebral catheter removed prematurely. They were given morphine PCA and included in our intention-to-treat analysis.
Demographic and morphometric characteristics of the participating patients and the types of surgery were similar in each group (Table 1). The number of patients receiving intraoperative opioids was similar in the groups: 5 patients each in the 15-min and 30-min lockout groups (28% vs 31%, respectively, P = 0.70).
We found no statistically significant difference in pain scores at rest Figure 1 or on movement between groups (Fig. 2). However, the 30-min group used less total volume of levobupivacaine had fewer demands and received fewer boluses. This was statistically significant (Table 2). The highest mean dynamic pain score was 27 ± 12 mm in 15-min lockout group and 35 ± 10 mm in the 30-min lockout group (P = 0.57).
View larger version (9K):
[in this window]
[in a new window]
|
Figure 1. Visual analog scale pain scores at rest. Values shown are mean ± sd. There were no significant differences between the groups. Open squares = 15-min lockout group: levobupivacaine 0.2% infusion at 8 mL/h with a 3 mL bolus and 15-min lockout. Filled squares = 30-min lockout group: levobupivacaine 0.2% infusion at 4 mL/h with an 8 mL bolus and 30-min lockout.
|
|
View larger version (9K):
[in this window]
[in a new window]
|
Figure 2. Visual analog scale pain scores on movement. Values shown are mean ± sd. No significant differences were found between groups. Open squares = 15-min lockout group: levobupivacaine 0.2% infusion at 8 mL/h with a 3 mL bolus and 15-min lockout. Filled squares = 30-min lockout group: levobupivacaine 0.2% infusion at 4 mL/h with an 8 mL bolus and 30-min lockout.
|
|
Two (11%) patients in the 15-min lockout group and 5 (28%) patients in 30-min lockout group required rescue analgesia (Table 2). The mean total morphine dose for those without PCA was 10 mg in the 15-min lockout group and 18 mg in the 30-min lockout group (P = 0.12).
Four patients (21%) in 15-min lockout group and 7 (39%) in 30-min lockout group who received postoperative adjunctive analgesia.
Hemodynamic variables and sedation scores were similar with each regimen (Table 3). Twenty-six percent of 15-min lockout group and 44% of the 30-min lockout group experienced nausea. One patient vomited (30-min lockout group). An antiemetic drug was required by 26% of the 15-min lockout group and 17% of the 30-min lockout. These differences did not reach statistical significance.
No patients experienced a pneumothorax. One patient in the 15-min lockout group developed Horner's Syndrome, and one patient in the same group experienced asymptomatic transient bradycardia (heart rate of 37 bpm), which resolved spontaneously. One patient had a catheter disconnection, lasting approximately 45 min, and one developed a wound infection (Table 3). Patient satisfaction scores were similar in the two groups (Table 3).
DISCUSSION
To our knowledge, this is the first report of PCPA for postoperative pain relief. Pain scores in both groups were low compared with previous studies of paravertebral analgesia for breast surgery.8,9 Few patients in either group required rescue analgesia. Both regimens were well tolerated and satisfaction scores were high indicating that this is a feasible technique in this population. Our data did not demonstrate any differences in primary outcome (i.e., pain scores) between the two regimens. Therefore, we cannot recommend one dosing regimen over the other. However, it appears that equally effective analgesia can be achieved with a lower total dose of levobupivacaine using a large bolus and long lockout regimen (30-min lockout group). This may suggest that the large volume, long lockout regimen is superior. However, there is the possibility of a type 2 error. The major weakness of our study was not comparing our PCPA technique with a continuous paravertebral infusion or to a placebo control group; however, the analgesic tolerability and satisfaction levels reported by our patients were comparable to those reported elsewhere by patients with continuous paravertebral infusion and higher than those who received PCA opiates.12 In conclusion, in this prospective, randomized, double-blind clinical trial we demonstrated that in patients having major breast cancer surgery PCPA offers excellent postoperative analgesia with few side effects and high patient satisfaction.
ACKNOWLEDGMENTS
Nancy Alsip, PhD, edited the manuscript, and Gilbert Haugh, MS, prepared the figures (both of the Outcomes Research Institute, University of Louisville).
Footnotes
Accepted for publication March 27, 2008.
Supported by The Mater College for Postgraduate Education & Research. Dr. Sessler's time was supported by NIH Grant GM 061655 (Bethesda, MD) and the Joseph Drown Foundation (Los Angeles, CA).
REFERENCES
- Apfelbaum JL, Chen C, Mehta SS, Gan TJ. Postoperative pain experience: results from a national survey suggest postoperative pain continues to be undermanaged. Anesth Analg 2003;97: 534–40[Abstract/Free Full Text]
- Macintyre PE. Safety and efficacy of patient-controlled analgesia. Br J Anaesth 2001;87:36–46[Abstract/Free Full Text]
- Dolin SJ, Cashman JN. Tolerability of acute postoperative pain management: nausea, vomiting, sedation, pruritis, and urinary retention. Evidence from published data. Br J Anaesth 2005;95:584–91[Abstract/Free Full Text]
- Taylor NM, Hall GM, Salmon P. Patients' experiences of patient-controlled analgesia. Anaesthesia 1996;51:525–8[Web of Science][Medline]
- Block BM, Liu SS, Rowlingson AJ, Cowan AR, Cowan JA Jr, Wu CL. Efficacy of postoperative epidural analgesia: a meta-analysis. JAMA 2003;290:2455–63[Abstract/Free Full Text]
- Correll DJ, Viscusi ER, Grunwald Z, Moore JH Jr. Epidural analgesia compared with intravenous morphine patient-controlled analgesia: postoperative outcome measures after mastectomy with immediate TRAM flap breast reconstruction. Reg Anesth Pain Med 2001;26:444–9[Web of Science][Medline]
- Wu CL, Cohen SR, Richman JM, Rowlingson AJ, Courpas GE, Cheung K, Lin EE, Liu SS. Efficacy of postoperative patient-controlled and continuous infusion epidural analgesia versus intravenous patient-controlled analgesia with opioids: a meta-analysis. Anesthesiology 2005;103:1079–88; quiz 1109–1010[Web of Science][Medline]
- Klein SM, Bergh A, Steele SM, Georgiade GS, Greengrass RA. Thoracic paravertebral block for breast surgery. Anesth Analg 2000;90:1402–5[Abstract/Free Full Text]
- Naja MZ, Ziade MF, Lonnqvist PA. Nerve-stimulator guided paravertebral blockade vs. general anaesthesia for breast surgery: a prospective randomized trial. Eur J Anaesthesiol 2003;20:897–903[Web of Science][Medline]
- Coveney E, Weltz CR, Greengrass R, Iglehart JD, Leight GS, Steele SM, Lyerly HK. Use of paravertebral block anesthesia in the surgical management of breast cancer: experience in 156 cases. Ann Surg 1998;227:496–501[Web of Science][Medline]
- Kairaluoma PM, Bachmann MS, Korpinen AK, Rosenberg PH, Pere PJ. Single-injection paravertebral block before general anesthesia enhances analgesia after breast cancer surgery with and without associated lymph node biopsy. Anesth Analg 2004;99:1837–43[Abstract/Free Full Text]
- Buggy DJ, Kerin MJ. Paravertebral analgesia with levobupivacaine increases postoperative flap tissue oxygen tension after immediate latissimus dorsi breast reconstruction compared with intravenous opioid analgesia. Anesthesiology 2004;100: 375–80[Web of Science][Medline]
- Stratmann G, Gambling DR, Moeller-Bertram T, Stackpole J, Pue AF, Berkowitz J. A randomized comparison of a five-minute versus fifteen-minute lockout interval for PCEA during labor. Int J Obstet Anesth 2005;14:200–7[Web of Science][Medline]
- Dernedde M, Stadler M, Bardiau F, Boogaerts JG. Comparison of 2 concentrations of levobupivacaine in postoperative patient-controlled epidural analgesia. J Clin Anesth 2005;17:531–6[Web of Science][Medline]
|
