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* From the Departments of Anesthesiology and Intensive Care, University Medical Centre Ljubljana, Ljubljana, Slovenia;
the Department of Anesthesiology and Intensive Care, Örebro Medical Center Hospital, Örebro, Sweden, and
the Clinical Department for general surgery and surgical infections, University Medical Centre Ljubljana, Ljubljana, Slovenia.
Address correspondence to: Dr. Neli Vintar, Clinical Department of Anesthesiology and Intensive Therapy, University Medical Centre, 1000 Ljubljana, Slovenia, Phone and Fax: ++386-01-52-22-234; E-mail: neli.vintar{at}mf.uni-lj.si
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Abstract |
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Methods: Two groups of patients for IHR were included in the randomized, double-blind study. An epidural catheter was placed in the surgical wound, tunneled subcutaneously and connected to a balloon-pump containing either 0.25% bupivacaine (B) or 0.25% ropivacaine (R). Postoperatively, the patient self-administered the LA into the wound. Administration could be repeated after 20 min. If moderate to severe pain still persisted, rescue medication (piritramid) was given intravenously. The variables recorded in both groups were: visual analogue scale (VAS), pain scores at rest and with movement, number of applications, wound healing, patients' satisfaction.
Results: During the first 24 hr, median number of LA applications in 26 B patients was 4 (range 1–6) and in 25 R patients 3 (range 1–5). Both groups showed low VAS pain scores: less than 2 at rest, less than 4 with movement. Eighty percent of patients of each group would choose this type of analgesia again. Two patients from B Group and three from R Group needed rescue medication. No wound infection was observed. There were no statistically significant differences between the groups.
Conclusion: Self-administration of the LA solution via a catheter in the surgical wound is an effective method of pain relief after IHR with little side-effects.
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Introduction |
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Postoperative pain is often treated with less potent opiods, non-steroidal anti-inflammatory drugs (NSAIDs) and/or paracetamol given by the oral or im route, but these methods are not always effective. Intravenous analgesia is predictable and effective but demands well defined safety measures and cannot be administered at home after day surgery.
Wound infiltration with local anesthetic (LA) has been evaluated in several studies and found to be a good method for postoperative pain relief.1,2,5,6 Incisional LA analgesia has been shown to diminish the need for opioids. However, these are all single dose studies.
Repeated doses of a LA solution via a catheter placed in the surgical wound have not been studied extensively. This method enables repeated applications of the LA postoperatively by nurses, on the surgical ward, or even by patients at home.3,7 The catheter can be connected to an elastomeric balloon-pump which delivers a given volume of LA solution determined by opening the clamp for a specific period of time.
The current study was performed to assess the safety and applicability of repeated administrations of LA into the surgical wound after hernioplasty by an elastomeric balloon-pump connected to a subcutaneously placed epidural catheter. The study was undertaken to compare the effectiveness of analgesia during rest and during movement, after the administration of 0.25% bupivacaine (B) or 0.25% ropivacaine (R).
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Methods |
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Sixty patients, American Society of Anesthesiologists physical status (ASA) I–II, between 16 and 70 yr of age, were randomly allocated to two groups. One group received 0.25% B (Group B) and the other 0.25% R (Group R) for postoperative pain relief.
Intraoperatively, subarachnoid blockade was performed in the lateral position, using a 25-G Sprotte Standard Needle with introducer-cannula (Pajunk), inserted at the L3–L4 interspace. 15 mg of hyperbaric 0.5% B were injected (marcaine spinal 0.5% heavy with glucose; 1 mL contains B hydrochloride 5 mg, dextrose monohydrate 80 mg).
The same surgeon performed all operations. The IHR was performed by the open tension-free suture-less procedure. While in conventional techniques tension is arising from approximation of musculoaponeurotic tissues, the use of a polypropylene mesh prosthesis made it possible to perform the repair without tension. In the procedure used, a plug was inserted in the internal ring and a patch was placed into the subaponeurotic space. The plug was fixed by one stitch to the transverse muscle and no stitch was used to fix the overlay mesh patch. It was sealed in place by the hydrostatic pressure from the surrounding tissues. Thus, absence of traction was achieved.
Before closing the wound, a multihole epidural catheter (Portex clear G 18 epidural catheter with three lateral eyes) was placed subcutaneously alongside the wound through a Tuohy needle inserted at a distance of 4–5 cm from the wound. The catheter was tunneled 4–5 cm subcutaneously by the surgeon, sutured and firmly secured to the skin by a sterile transparent dressing. Using an aseptic technique, the catheter was connected to an elastomeric (balloon) pump (Home pump, I-Flow Corporation, Lake Forest, California, USA) containing 60 mL of 0.25% B (Group B) or 0.25% R (Group R). Postoperatively, when the visual analogue score (VAS) pain score was > 3, the LA infusion was started by opening the clamp. The patient stopped the infusion by closing the clamp after six minutes, so that the pump delivered 10 mL of LA.
The nurses on the ward were taught to use the VAS to determine the intensity of pain at six-hour time intervals. At 6 p.m., patients were requested to stand and walk, at which time pain at rest and during movement was assessed. On the next morning, at 8 a.m., pain was assessed under the same conditions. If the pain score was 3 or more 20 min after the first 10 mL of LA, another 10 mL of LA was self-administered with the pump. If the pain persisted, 3 mg of piritramid were given intravenously as rescue analgesia.
Piritramid is a potent opioid analgesic with hypnotic effect, synthetized in the laboratories of Janssen Pharmaceutica in the early 60's. Compared to morphine, 15 mg of piritramid are equivalent to 20 mg of morphine; naloxone is the antidote.
Each patient was given a form, on which the following variables were recorded by nurses: pain intensity, assessed by nurses every six hours and/or before and after each treatment, pain at rest and upon movement (5 m walk) at 6 p.m. after the operation and at 8 a.m. the next day, the time of day of each LA administration, the use of rescue iv analgesic medication. Although the patients self-administered the LA, they called the nurse to record the administrations to facilitate data collection for this study. The total number of times the LA was self-administered, technical problems with the pump, possible side effects or complications, overall satisfaction/dissatisfaction with analgesia (better than expected, as expected, worse than expected) were recorded by residents at 6 p.m. and 8 a.m. the next morning. The patients were also asked if they would decide in favour of this method of analgesia in case of another operation in the future. The resident removed the catheter 24 hr after insertion and sent the tip for microbiological analysis.
The patients were examined one week after the operation and the surgical wound was evaluated as: healing without complications; inflammation of the skin around the wound. The surgeon reported his observations to the anesthesiologist who recorded them on the patients' forms.
Statistical analysis
Descriptive statistics are reported as mean ± SD. Because the pain scores obtained in both groups at different times were not normally distributed, they were compared using the nonparametric analog to the t test, the Mann-Whitney test. A P value less than 0.05 was considered to be statistically significant. We compared patients' satisfaction with analgesia between the groups using the chi-square test with Yate's correction.
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Results |
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). Patients did not require any sedatives or analgesics during surgery. Sixty patients were enrolled in the study, only 51 were evaluated (two patients mistakenly received 60 mL of LA rapidly, seven patients did not require any postoperative analgesic).
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Table II shows numbers of LA administrations in both groups of patients.
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shows total piritramid consumption in patients of both groups.
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).
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).
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Complications
In two cases, one from Group B and one from Group R, the clamp of the balloon-pump was not closed properly after self-administration of the LA. As a result, 60 mL of 0.25% B or 60 mL of 0.25% R were infused in the patient's wound in about 35 min. Both patients were monitored carefully (electrocardiograph, noninvasive blood pressure measurements in ten-minute intervals, pulse oxymety) and asked regularly for any clinical signs of systemic toxicity, such as tinnitus, metallic taste, numbness of the tongue. No clinical signs of LA toxicity were observed.
Microbiological analysis of catheter tips and wound healing
Staphylococcus epidermidis was isolated on the tips of three catheters in Group R and on four in Group B, while the remaining were sterile.
No signs of local inflammation were noted in any of the patients. Wound healing assessed by the surgeon was considered normal in all patients.
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Discussion |
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Both B and R given as 0.25% solutions administered subcutaneously, even in rather small volumes of 10 mL to 20 mL, proved effective and safe in treating pain after hernioplasty.
In single dose studies by different authors2,5–11 different volumes and concentrations of LA have been used for wound infiltration at the end of hernioplasty. Doses of 40 mL of 0.75% R,2 30 mL of 0.5% and 30 mL 0.75% R,6 40 mL–50 mL 0.75% R,9 30 mL 0.25% B,10 40 mL 0.25% R and 40 mL 0.25% B7 doses have been studied. The LA was injected into various layers of the surgical wound: under the fascia,3,5 subcutaneously11 and into the edges of the wound,2,3,6,8–10 subcutaneously and into the muscle.12 When added to the LA and used in single doses, NSAIDs13 and clonidine10 did not significantly prolong the duration of analgesia.
Our study shows that rather small volumes and low concentrations of LA (10 mL of 0.25% R or B) are effective in providing sufficient analgesia – at rest and with movement. Only three patients from Group R and two from Group B required rescue analgesia. In our study, the surgeon placed the epidural catheter subcutaneously alongside the wound. The reason why subcutaneous analgesia alone (as opposed to infiltration in multiple layers of the wound) is effective in the present study may be due to the surgical approach adopted at our centre, which causes less pain than usual. This surgical approach is not different by the type or size of incision but less tension is created.
A serious concern with the type of pump used is that the entire volume of LA can be delivered if the patient or the nurse fails to close the clamp. To avoid this, the following steps were taken: a) precise oral and written instructions were given to the patient and to the nursing staff; b) the use of a timer was encouraged; c) the patient was instructed to close the clamp and contact the nurse if he/she felt numbness of the tongue or tinnitus; and d) the nurse was instructed to call the anesthesiologist in such a case. In spite of all safety measures, in one patient 60 mL of 0.25% R and in another 60 mL of 0.25% B were injected into the wound accidentally on the surgical ward. Yet, no toxic effects were observed. Analgesia in both cases was long lasting: the patient in Group B needed no other medication for 24 hr, while the patient from Group R took the rescue medication once. We did not measure blood levels of the LA; however, all plasma levels reported in the literature8,9,14 after even higher doses of B (repeated administrations of 20 mL of 0.5% B)14 or R (30 mL, 40 mL, 50 mL of 0.75% R)8,9 did not show toxic levels of LA.
The recent availability of newer and safer elastomeric pumps can be expected to reduce the risk of overdose. This pump allows delivery of LA only if the patient presses a button, a safety feature that eliminates the risk of accidental delivery of the entire content of the pump. Pressure on the button for 45 sec allows the patient to receive 10 mL of LA (I-Flow Corp, USA). Light-weight delivery pumps with lockout function have also become available (Microject pump, Sorenson Medical, USA). Such devices have improved the safety of patient controlled regional anesthesia (PCRA) techniques outside the hospital. However, controlled trials are necessary to confirm the safety of these pumps.
Other theoretical concerns relate to the risk of delayed wound healing and infection. However, the literature on the subject does not support these concerns: LA drugs even have bacteriostatic and antimicrobial effects.15 No signs of local inflammation were noted in any patient and wound healing was normal.
The great majority of patients from both groups were very satisfied with this method of pain relief, as over 80% of them would decide in favour of using PCRA again. They expressed their desire to take "their" pumps home with them when they left the hospital. We consider this technique appropriate not only for inpatients but also for outpatients; however, more reliable pumps will be required.
The patients in our study needed very little rescue medication – i.e., opioids. Therefore, good analgesia without sedation, nausea, vomiting and risk for respiratory depression was ensured in both groups.
Our double-blind randomized study showed that incisional analgesia with self-administration of a LA on demand is an effective method of pain relief after IHR. Further studies are necessary to determine the optimal concentration and volume of LA for pain relief after other surgical procedures. The role of opioids, NSAIDs and clonidine as adjuvants to LA drugs also needs to be studied.
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Acknowledgments |
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Revision received January 18, 2002. Accepted for publication March 2, 2001.
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References |
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2 Pettersson N, Berggren P, Larsson M, Westman B, Hahn RG. Pain relief by wound infiltration with bupivacaine or high-dose ropivacaine after inguinal hernia repair. Reg Anesth Pain Med 1999; 24: 569–75.[Medline]
3 Rawal N, Axelsson K, Hylander J, et al. Postoperative patient-controlled local anesthetic administration at home. Anesth Analg 1998; 86: 86–9.[Medline]
4 Schindler M, Swann M, Crawford M. A comparison of postoperative analgesia provided by wound infiltration or caudal analgesia. Anaesth Intensive Care 1991; 19: 46–9.[Medline]
5 Bültmann M, Streich R, Risse A, Falke KJ, Pappert D. Postoperative analgesia in children after hernioplasty. Wound infiltration with different concentrations of bupivacaine: a pilot study (German). Anaesthesist 1999; 48: 439–43.[Medline]
6 Mulroy MF, Burgess FW, Emanuelsson B-M. Ropivacaine 0.25% and 0.5%, but not 0.125%, provide effective wound infiltration analgesia after outpatient hernia repair, but with sustained plasma drug levels. Reg Anesth Pain Med 1999; 24: 136–41.[Medline]
7 Dierking GW, Østergaard E, Østergård HT, Dahl JB. The effects of wound infiltration with bupivacaine versus saline on postoperative pain and opioid requirements after herniorrhaphy. Acta Anaesthesiol Scand 1994; 38: 289–92.[Medline]
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Horn E-P, Schroeder F, Wilhelm S, et al. Wound infiltration and drain lavage with ropivacaine after major shoulder surgery. Anesth Analg 1999; 89: 1461–6.
9 Pettersson N, Emanuelsson B-M, Reventlid H, Hahn RG. High-dose ropivacaine wound infiltration for pain relief after inguinal hernia repair. A clinical and pharmacokinetic evaluation. Reg Anesth Pain Med 1998; 23: 189–96.[Medline]
10
Elliott S, Eckersall S, Fligelstone L, Jothilingam S. Does the addition of clonidine affect duration of analgesia of bupivacaine wound infiltration in inguinal hernia surgery? Br J Anaesth 1997; 79: 446–9.
11 Erichsen CJ, Vibits H, Dahl JB, Kehlet H. Wound infiltration with ropivacaine and bupivacaine for pain after inguinal herniotomy. Acta Anaesthesiol Scand 1995; 39: 67–70.[Medline]
12 Cherian MN, Mathews MP, Chandy MJ. Local wound infiltration with bupivacaine in lumbar laminectomy. Surg Neurol 1997; 47: 120–3.[Medline]
13 Reuben SS, Duprat KM. Comparison of wound infiltration with ketorolac versus intravenous regional anesthesia with ketorolac for postoperative analgesia following ambulatory hand surgery. Reg Anesth 1996; 21: 565–8.[Medline]
14 Kastrissios H, Triggs EJ, Sinclair F, Moran P, Smithers M. Plasma concentrations of bupivacaine after wound infiltration of an 0.5% solution after inguinal herniorrhaphy: a preliminary study. Eur J Clin Pharmacol 1993; 44: 555–7.[Medline]
15 Rosenberg PH, Renkonen OV. Antimicrobial activity of bupivacaine and morphine. Anesthesiology 1985; 62: 178–9.[Medline]
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