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* From the Departments of Anesthesia and Pain Medicine,
Pediatrics,
Research Unit, and
¶ Surgery, Makassed General Hospital;
the Faculty of Public Health, Lebanese University, Beirut, Lebanon; and the
Department of Anesthesia & Intensive Care, KS/Astrid Lindgrens Children’s Hospital, Stockholm, Sweden.
Address correspondence to: Dr. Zouheir Naja, Department of Anesthesia and Pain Medicine, Makassed General Hospital, P.O. Box: 11-6301 Riad El-Solh 11072210, Beirut, Lebanon. Phone: 961 1 655 466; Fax: 961 1 646 589; E-mail: zouhnaja{at}yahoo.com
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Abstract |
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Methods: This was a prospective randomized observer-blinded study. Following Ethics Committee approval and informed consent, 80 patients scheduled for hemorrhoidectomy were randomized to two groups of 40 patients each: general anesthesia alone, or nerve stimulator guided pudendal nerve block. Postoperative pain, the primary outcome variable of the study, was assessed by visual analogue scale scores at predetermined intervals during the postoperative period. Analgesic consumption, time to return to normal activities, patients’ and surgeons’ satisfaction, and duration of hospital stay were recorded.
Results: The guided pudendal nerve block group failed in three patients, requiring their conversion to general anesthesia. Otherwise, patients in the pudendal nerve block group experienced better postoperative pain relief at rest (P < 0.0001), on walking, sitting, and defecation (P < 0.001), reduced need for opioids (11/35 vs 32/37; P < 0.0001), a more rapid return to normal activities (7.2 vs 13.8 days; P < 0.0001) and also a shorter hospital stay (25/35 vs 3/37 outpatient cases; P < 0.0001) compared to the general anesthesia group. Pudendal nerve block was also associated with overall higher patient satisfaction compared to general anesthesia (30/35 vs 9/37; P < 0.0001).
Conclusion: Nerve stimulator guided pudendal nerve block is associated with reduced postoperative pain, shortened hospital stay, and earlier return to normal activity compared to general anesthesia for hemorrhoidectomy.
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Introduction |
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In a recent randomized double-blind study we showed that nerve-stimulator guided pudendal nerve block (PNB) combined with GA reduces postoperative pain, and results in a shorter hospital stay and earlier return to normal activity compared to GA alone.8 Based on the positive results achieved with this type of PNB, we hypothesized that it would be possible to perform hemorrhoidectomy without concomitant GA. Thus, we undertook a prospective randomized observer-blinded study to compare nerve-stimulator guided PNB with sedation, to GA in patients undergoing hemorrhoidectomy. We hypothesized that patients treated with PNB would experience better and more prolonged postoperative analgesia.
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Methods |
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Patients with chronic renal failure, coagulopathy, symptoms of bladder neck obstruction, or patients for whom it would not be possible to conduct a telephone follow-up were not eligible for study inclusion. All patients underwent open radical hemorrhoidectomy. Skin flaps were raised next to the squamocutenous junction to reduce the risk for postoperative stricture. Flaps were raised up to the dentate line (origin of the plexus). The plexus was excised and the rectal mucosa was sutured to the fibres of the internal sphincter muscle.
Induction of anesthesia for patients in the GA group was achieved with fentanyl 1.5 µg·kg–1 iv and propofol 1 to 2 mg·kg–1 iv, followed by endotracheal intubation facilitated with atracurium 0.5 mg·kg–1 iv. Anesthesia was maintained using sevoflurane 1–3% end-tidal concentration, nitrous oxide 70% and oxygen 30%. The sevoflurane concentration was adjusted as required to maintain heart rate and blood pressure within ± 25% of pre-induction levels.
In the PNB group, blocks were performed with the patient in the lithotomy position. Patients received supplemental oxygen by facemask and fentanyl 1 µg·kg–1 iv was administered following application of routine anesthetic monitors. Upon request, sedation was enhanced prior to the block using midazolam 1–2 mg iv. After aseptic preparation of the skin, four injection sites were infiltrated, each with 1% lidocaine 1 mL. At the posterior injection points at four and eight o’clock (Figure 1
) a 22-G 10 cm nerve stimulator needle (Stimuplex, B.Braun, Melsungen, Germany) was subsequently advanced approximately 7 to 10 cm (depending on patient size) perpendicularly to the skin in all planes, using a stimulating current of 2.5 to 5.0 mA at 1 Hz (Stimuplex, B.Braun, Melsungen, Germany). When appropriate nerve stimulation of the pudendal nerve with its inferior rectal nerve and perineal branches could be verified (visualized as ipsilateral contractions of the posterior parts of the anal sphincter), the needle-tip position was optimized in a normal fashion by preserving muscle contractions while reducing the stimulating current to 0.5–0.6 mA, and the injection was performed.
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A local anesthetic volume of 0.2 mL·kg–1 was injected at each of the posterior injection points (four and eight o’clock) and 0.15 mL·kg–1 was injected at each of the anterior injection points (2 and 10 o’clock) for a total injection volume of 0.7 mL·kg–1. Each 20 mL of the local anesthetic mixture contained: 2% lidocaine 6 mL, lidocaine 2% 6 mL with adrenaline 5 µg·mL–1, 0.5% bupivacaine 5 mL, fentanyl 50 µg, and clonidine 150 µg. This mixture has previously been reported to provide long-lasting postoperative analgesia after peripheral nerve blocks performed for various types of surgical interventions.8,10–13 Verification of adequate distribution of cutaneous anesthesia was determined by a pinprick test. The onset time of the block was usually 15 to 20 min. Intraoperatively, if the patient requested additional sedation due to discomfort or pain, propofol supplementation was provided in 10 to 20 mg iv increments (maximum dose 50 mg). The additional sedation was titrated so that verbal contact was always maintained with the patient. In the event of overt block failure, as indicated by insufficient sphincter relaxation or unacceptable patient discomfort, the technique was abandoned and conversion to GA took place, according to the technique described above.
Postoperative pain management protocol
Patients with a visual analogue scale (VAS) > 4 during their hospital stay received pethidine l mg·kg–1 im as supplemental analgesia, whereas patients with a VAS score < 4 received a combination of dextropropoxifen 30 mg po and paracetamol 400 mg po. Following discharge, patients were prescribed lactulose 20 mL po bid and diclonefac sodium 50 mg po tid for three weeks. Patients were also prescribed an oral dextropropoxifen/paracetamol combination if they required additional analgesia following hospital discharge.
Data collection
Postoperative data collection was peformed by a trained research nurse who was blinded to patient group allocation. Postoperative VAS pain scores were considered the primary outcome variable of the study. The VAS scores (0- no pain and 100- worst possible pain) at rest, on walking, and sitting were assessed at predetermined intervals postoperatively (6 hr, 12 hr, 24 hr, 36 hr, 48 hr, 3 days, 4 days, 5 days, and 6 days). Pain associated with the first six episodes of defecation, and opioid consumption for the first six postoperative days were also recorded. Following hospital discharge, patients were instructed to record the following: number of postoperative days required to be able to sit, to walk, and to defecate without pain. The times (in days) until return to work (employed patients) or to resume normal activities of daily living (unemployed patients) were also recorded.
Demographic data, duration of surgery, duration of recovery room stay, patient satisfaction, postoperative nausea and vomiting, duration of hospital stay, duration of sick leave time, and complications were recorded. Non-invasive measures of mean arterial pressure, heart rate and oxygen saturation were recorded pre- and postincision. In Group PNB sphincter relaxation was also assessed by the surgeon. If complete sphincter relaxation was not obtained following administration of the block and supplemental sedation, the block was considered to have failed, and the patient was converted to GA.
The decision to discharge the patient from hospital was made by the surgeon according to established clinical routine (discharge criteria: adequate control of pain and postoperative nausea and vomiting, ambulation without aid, and ability to void spontaneously). The patient’s overall level of satisfaction was assessed by telephone interview one month postoperatively. Patients were asked to quantify their degree of satisfaction as satisfied, moderately satisfied, or unsatisfied. Patients were also asked whether they would choose the same type of anesthesia if they required a repeat procedure, and if they would recommend the same anesthetic to a sibling or friend who required the same type of surgery.
Statistical considerations
Based upon standard deviations in VAS scores from our previous study,8 40 patients in each group were required in order to detect a 25% difference in VAS scores at all predetermined time intervals of the postoperative period between groups, with a confidence level of 95% (
= 0.05) and a power of 90% (ß = 0.10).
Student’s t tests were used to test for differences between groups with respect to age, height, weight, body mass index, recovery room length of stay, time to resume normal activities, and number of days with pain on walking, sitting and at defecation. Chi-squared tests were used to test for differences in postoperative nausea and vomiting, urinary retention and incontinence, readmission due to severe pain, duration of hospital stay, postoperative patient satisfaction, and need for supplemental analgesics. Repeated measures ANOVA was used for between-groups comparison of hemodynamic parameters and VAS pain scores at rest, on sitting, and on walking. Statistical significance was assumed with a P-value < 0.05.
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Results |
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The study groups were similar with respect to gender distribution, age, height, weight, body mass index, Shackelford’s classification grade, and duration of surgery (Table I). Twenty-three PNB patients requested sedation with midazolam for performance of the block. Seven of the PNB patients received supplemental propofol during the surgical procedure and of these seven patients, three patients were converted to GA due to block failure (Table I).
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). Opioid consumption was also significantly lower in association with PNB compared to GA throughout the follow-up period (P < 0.0001, Figure 3). In addition, pudendal nerve block patients experienced significantly shorter periods (days) of pain associated with walking, sitting and defecation compared to GA patients (Table II).
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). Pudendal nerve block patients were discharged from hospital more quickly than GA patients (P < 0.0001, Table II). In addition, PNB patients resumed normal activities more rapidly in comparison to GA patients (P < 0.0001, Table II). Patient and surgeon’s satisfaction responses are presented in Table II. |
Discussion |
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The results of this investigation corroborate the findings from our previous study,8 and demonstrate that hemorrhoidectomy can be performed successfully in either awake or moderately sedated patients. Although the benefits of performing hemorrhoidectomy without general anesthesia may be of modest overall importance in otherwise healthy individuals, patients with associated co-morbidities, including cardiopulmonary disease, could potentially benefit from this regional anesthetic option.
A striking observation was the duration of analgesia, as pudendal block produced a clinically significant reduction of postoperative pain, both at rest and on activity, for up to six days postoperatively. Relief of pain during defecation post-hemorrhoidectomy, frequently described as "passing bits of broken glass"14 would be especially important to these patients.
Improved analgesia associated with a pudendal block, compared to a more traditional approach, resulted in several secondary benefits, including lower requirements for analgesic medications, earlier discharge from the hospital, and a shorter time to resumption of normal activities. The advantage of hemorrhoidectomy as an outpatient procedure, and facilitating an earlier return to work with this technique, benefit the patient and the health care system. Furthermore, patient satisfaction is of increasing importance in many health care systems. Ratings of overall satisfaction and willingness to have the same anesthetic regimen again were significantly greater amongst pudendal block patients, compared to subjects who received GA and opioids.
The large difference between study groups with respect to both the incidence and duration of postoperative pain at rest, and during activity, deserve careful consideration. Since the duration of pain relief associated with PNBs considerably exceeded the expected duration of the local anesthetic component of the mixture used for the block (five to six hours), effective blockade of afferent pain impulses during the surgical procedure and the early postoperative period may have achieved a pre-emptive analgesic effect. Such an effect could be the result of a reduction in nociceptive plasticity within the central nervous system (i.e., reduced wind-up, reduced recruitment of silent nociceptive neurons).15,16 Another possible factor could have been a more local effect at the level of the injured perianal nerves. Both Gianonni et al.17 and Lavand’homme and Eisenach18 have described the potent effects of peripheral administration of a mixture of local anesthetics and clonidine when injected close to injured nerves or nerve endings. Opioid medications added to local anesthetic solutions have also been shown capable of prolonging the duration of peripheral nerve blocks.19,20
There are several limitations associated with the PNB technique and study design. First, despite improved precision of nerve blocks achieved with nerve-stimulation guidance, conversion to GA was required in 7.5% of patients. It is likely that block failure rates could have been improved if the blocks had been systematically repeated at any of the four injection points which demonstrated only partial loss of sensation to a pin-prick test. For this study, we injected the posterior and anterior points just once. Gabrielli et al.4 reported a 100% success rate associated with PNB in a series of over 400 patients, where repeated small anesthetic injections were performed amongst the deep and superficial planes, as required, during the operation. With respect to study design, it is difficult to achieve adequate blinding when comparing GA to a regional technique. In an attempt to address this problem, the first postoperative assessment by the blinded research nurse was delayed until six hours after completion of surgery. However, it may have been possible even at this point for the trained observer to have predicted to which treatment group the patients belonged. Finally, the design did not take into consideration potential benefits accrued by local anesthetic supplementation for patients who receive general anesthesia, a technique commonly practiced at some centres.
In summary, this clinical trial demonstrates that PNB presents an effective alternative to GA for hemorrhoidectomy. Measures to reduce our observed 7% failure rate are suggested. The described regional technique is associated with reduced postoperative pain, a shorter duration of hospital stay, high patient satisfaction, and an earlier resumption of normal activities in comparison to GA for this procedure.
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Acknowledgments |
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Footnotes |
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Competing interests: None declared.
Accepted for publication December 8, 2005. Revision accepted January 13, 2006.
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References |
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18 Lavand’homme PM, Eisenach JC. Perioperative administration of the alpha2-adrenoceptor agonist clonidine at the site of nerve injury reduces the development of mechanical hypersensitivity and modulates local cytokine expression. Pain 2003; 105: 247–54.[Medline]
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= the covered anesthetized area with the summit in the perineal area and the base joining the two posterior points.
