Retrobulbar Bupivacaine Irrigation for Postoperative Pain after Scleral Buckling Surgery A Prospective Study JAYS. DUKER, MD/· 2 JARL NIELSEN, MD, 3 JAMES F. VANDER, MD, 3 REBECCA B. ROSENSTEIN, PhD, 2 WILLIAM E. BENSON, MD3

Abstract: The authors conducted a prospective, randomized, double-masked clinical trial to determine if retrobulbar irrigation with bupivacaine hydrochloride 0.75% (Marcaine) has an effect on postoperative pain after scleral buckling surgery. Fifty consecutive patients undergoing scleral buckling under general anesthesia were randomized to receive either bupivacaine or balanced salt solution as a retrobulbar irrigation at the end of their retinal detachment procedure. Of the 25 patients who received bupivacaine, only three (12%) required parenteral pain relief in the first 24 hours after surgery. This was statistically significant when compared with the 18 (72%) of 25 patients requiring parenteral pain relief in the placebo group (P < 0.0001 ). In addition, when questioned about their perception of the degree of postoperative pain, patients in the control group rated their level of pain as significantly more severe than did patients in the bupivacaine group. The authors conclude that retrobulbar irrigation with bupivacaine is a safe and effective way to achieve postoperative pain relief after surgery for scleral buckling. Ophthalmology 1991; 98:514-518

Recently, a novel approach for the primary delivery of local anesthetic agents to the retrobulbar space as well as Originally received: October 15, 1990. Revision accepted: December 3, 1990. 1

Retina Associates, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston. 2 Eye Research Institute, Boston. 3 Retina Service, Wills Eye Hospital, Thomas Jefferson University, Philadelphia. Dr. Nielsen is currently in private practice in San Bernadino, CA. Presented as a poster at the American Academy of Ophthalmology Annual Meeting, Atlanta, OctjNov 1990. Reprint requests to JayS. Duker, MD, Library, Eye Research Institute, 20 Staniford St, Boston, MA 02114.

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the secondary augmentation of traditional retrobulbar blocks has been described for use in retinal detachment surgery. 1•2 The technique consists of a retrobulbar irrigation of the anesthetic agent(s) after a conjunctival peritomy and dissection of Tenon's fascia has been performed. Potential complications are minimized since neither a needle nor an injection are involved. Consequently, the risk of globe perforation and intravascular or intraneural injection of the anesthetic agent is extremely remote. We postulated that a similar technique may be efficacious in reducing the degree of postoperative pain after surgery for retinal detachment performed under general anesthesia. To test this hypothesis, we designed a prospective, randomized, double-masked clinical trial to study the effects of retrobulbar irrigation with bupivacaine

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RETROBULBAR BUPIVACAINE IRRIGATION

Fig 1. A 5-ml syringe containing bupivicaine hydrochloride 0.75% and tipped with a 21-gauge blunt irrigating cannula is advanced into the retrobulbar area in preparation for the irrigation.

hydrochloride 0.75% (Marcaine) on the degree of postoperative pain after surgery for scleral buckling.

PATIENTS AND METHODS Fifty consecutive patients undergoing surgery for scleral buckling under general endotracheal anesthesia were enrolled in this study. Cases performed under local anesthesia were excluded because variability in the effects of the initial retrobulbar block on subsequent pain levels could not be accurately assessed. Other exclusion criteria included age younger than 18 years or a history of sensitivity to local anesthesia. Exoplants using solid silicone or silicone sponges were used in all cases. Retinopexy, when indicated, was achieved with cryotherapy or indirect laser in the pure scleral buckling cases. In the few enrolled cases that included a pars plana vitrectomy, endolaser retinopexy also was used. The 50 patients were randomly assigned to either the study group or the control group. Randomization was accomplished via serially numbered, sealed envelopes containing either the word "study" or "control." A single envelope was opened during the course of the surgical procedure by the circulating nurse and the nurse anesthetist, and only those two individuals were initially informed of the patient's assignment. Assignment to the study group meant that a disposable syringe containing 4 ml of0.75% bupivacaine hydrochloride was prepared. If the patient was assigned to the control group, 4 ml of balanced salt solution was placed in the syringe. A 21-gauge blunt irrigating cannula was positioned on the syringe. Care was taken to ensure that neither the operating surgeon nor the assistant surgeon was aware of the contents of the syringe. However, the contents of the syringe and the amount of solution used were recorded on the anesthesia record.

At the end of the scleral buckling procedure, before closure of the conjunctiva, the retrobulbar area was infiltrated with the contents of the syringe. The conjunctiva and Tenon's fascia were grasped with forceps, elevated from the globe, and the blunt tipped irrigator was directed posteriorly toward the optic nerve (Fig 1). Each of the four quadrants was successively irrigated between the rectus muscles. In most cases, the cannula could be safely advanced into the retrobulbar space so that the hub was at the level of the comeoscleral limbus. When scleral buckling material was present in the quadrant, care was taken to avoid the exoplant. In cases in which all four quadrants were opened, 1 ml was placed in each quadrant. In instances where less than a 360° peritomy was performed, then the full contents of the syringe was evenly divided between the available quadrants. In all cases, the excess anesthetic agent was allowed free egress from the retrobulbar space. After irrigation, the conjunctiva was closed in a standard fashion with interrupted absorbable sutures. All patients were kept in the hospital for at least 24 hours after surgery. Postoperative pain medications were delivered exclusively by the registered nurses in the postoperative area and/or on the hospital inpatient floors. So as not to bias the delivery of pain medication, the nursing personnel were made aware that a study was in progress, however, they were not told which specific patients were participating or which irrigation solution the participating patients received. The postoperative pain medications consisted of oral acetaminophen (Tylenol) 650 mg, oral codeine 60 mg with acetaminophen 650 mg, or intramuscular meperidine (Demerol), 75 mg to 100 mg. The precise dosage of meperidine was determined by body weight, with patients weighing over 200 pounds receiving the higher dosage. The orders for all pain medications were written on an "on demand" basis (i.e., as occasion requires), for intervals of every 4 hours. The treating nurses were solely responsible for deciding which of the three pain medications to give, based on their assessment of the patient's pain levels and the patient's previous responses (if any) to medication. If either of the oral agents were given initially, and, after 1 hour, insufficient pain relief was achieved, then intramuscular meperidine was given. Baseline demographic data along with surgery-related variables were recorded for all enrollees. The main outcome of interest was the degree of postoperative pain. This was measured in two ways: by recording the amount of pain medication administered and by querying the patients as to their level of discomfort. On the first postoperative day, the assistant surgeon, who was still unaware of the irrigation solution used, questioned the patients with respect to their degree of pain and nausea. Pain was rated by the patient from 0 to 6, with 0 representing "no pain," l representing "barely felt," 2 representing "minimal," 3 representing "mild," 4 representing "moderate," 5 representing "severe," and 6 representing "worst pain ever." Each patient was informed of all 6 pain categories, and then asked to select the most 515

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appropriate level experienced. Nausea was rated on a scale from 0 to 4, with 0 representing none and 4 representing worst nausea ever. At this time, qualitative estimates of the amount of lid edema and chemosis also were made by the assistant surgeon. After the patient's qualitative assessment of the pain level was recorded, a quantitative estimate for the degree of pain was derived from the amount of pain medication given to the patient during the first 24 postoperative hours. This information was obtained from the nursing medication records. The dosage and number of doses of intramuscular meperidine, oral acetaminophen with codeine, and oral acetaminophen were recorded. Lastly, the anesthesia record was examined, showing the type of irrigating solution used. Comparisons of proportions were made using Pearson's chi-square statistic. The data were analyzed on a personal computer using the SAS software·package (Carey, NC).



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Table 1. Summary of Clinical and Surgical Parameters for the 50 Patients

Age (mean) Sex Male Female Race White Black Eye Right Left Procedure Primary Reoperation Size of peritomy 360° 180°

goo

Study Group (n = 25)

Control Group (n = 25)

56.7 years

55.2 years

12 (48%) 13 (52%)

15 (60%) 10 (40%)

22 (88%) 3 (12%)

24 (96%) 1 (4%)

12 (48%) 13 (52%)

14 (56%) 11 (44%)

22 (88%) 3 (12%)

20 (80%) 5 (20%)

20 (80%) 3 (12%) 2 (8%) 17 (68%)

20 (80%) 2 (8%) 3 (12%) 19 (76%)

RESULTS

Encircling band

Of the 25 patients who received bupivacaine irrigation (study group), 13 were female and 12 were male. The mean age was 56.7 years (range, 18-87 years). In this group, 22 patients were white and 3 were black. Operations were performed on 12 right eyes and 13 left eyes. Three of the procedures were reoperations and three eyes underwent pars plana vitrectomy in addition to scleral buckling as a part of their procedure. The mean age of the 25 patients who received the placebo irrigation of balanced salt solution (control group) was 55.2 years, (range, 25-8I years). In this group, 24 patients were white and I was black. There were I5 men and 10 women in this group. Fourteen right eyes and II left eyes were operated on. Five of the operations were reoperations and three included a pars plana vitrectomy. The patient characteristics and baseline surgical data for the two groups are summarized in Table I. With respect to the type and amount of pain medication required, only 3 (I2%) of the 25 bupivacaine-treated patients required parenteral pain relief with meperidine in the first 24 hours after surgery. This is contrasted to I8 (72%) of 25 of patients in the control group. This difference was highly significant (P < 0.000 I). Regarding the use of any narcotic analgesics (either intramuscul::.r meperidine or oral codeine with acetaminophen) only 9 (36%) of the bupivacaine-treated patients required a narcotic analgesic for pain relief compared with I9 (7 6%) of the control group (P < 0.004). With respect to the subjective levels of pain, seven categories were used with 0 being no pain and 6 being the worse pain ever felt. The distributions of the responses are shown in Table 2. When the ratings fell between categories, then the worse category was used, (i.e., 2.5 became a 3). To evaluate the data, the degree of pain was broken down into three categories: none to slight (0 to 2), mild to moderate (3 and 4), and severe (5 and 6). For the pa-

tients who received bupivacaine, 2I (84%) reported none to slight pain, whereas the remaining 4 patients ( I6%) reported mild to moderate pain. For the patients in the control group, 8 (32%) reported none to slight pain, I3 (52%) had mild to moderate pain, and 4 ( I6%) had severe pain. These differences were highly significant (P = 0.001 ). To test the internal consistency of the patients' subjective pain ratings and the "objective" nursing personnel's assessment of pain level, the patients' pain responses were further categorized according to whether parenteral pain medication was administered. For the 21 patients who were judged by the nursing staff to be in enough pain to necessitate intramuscular meperidine, the average pain assessment was 3.12. Six (29%) of these patients rated their pain in the none to slight classification, 12 (57%) rated pain as moderate, and 3 (I4%) rated pain as severe. This is contrasted to the average pain rating of 1.81 for the 29 patients who did not receive intramuscular meperidine. In this group, there were 19 (66%) patients who rated pain as none to slight, 5 ( 17%) who rated pain as moderate, and 1 (3%) who rated pain as severe. These differences were statistically significant (P < 0.004), confirming that the nursing staff administered parenteral pain medication to the patients with more severe discomfort. As for the levels of nausea noted, only three patients in the study group and five patients in the control group reported any nausea at all, with no patient rating the nausea level worse than a 2. There was no difference in the level of nausea between the two groups. No local or systemic complications of the retrobulbar irrigation with either bupivacaine or balanced salt solution were detected. In some cases, Tenon's fascia became temporarily hydrated and edematous secondary to the volume of liquid. used, but in no instance did this interfere with

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Table 2. Summary of Qualitative Patient Responses of the Level of Postoperative Pain Number of Patients Giving Each Pain Response "Barely Felt"

"Slight"

3 "Mild"

2 1

2

8

11 5

6

0

Study group Control group

2

"None"

1

conjunctival closure. No difference in the postoperative amount of lid edema or chemosis was evident between the two groups.

DISCUSSION This study shows that retrobulbar irrigation with bupivacaine effectively reduces the amount of postoperative discomfort associated with scleral buckling surgery performed under general anesthesia. During the first 24 postoperative hours, moderate to severe periocular pain often accompanies scleral buckling surgery. 3 In many cases, this requires either oral or parenteral narcotic analgesics for pain relief. Along with monitoring the patient for postoperative infection and elevated intraocular pressure, the administration of parenteral pain medications is one of the major reasons that most scleral buckling surgery is currently performed on an inpatient basis. An alternative method to the oral or parenteral systemic administration of medications for achieving analgesia of the eye and adnexa has been well known since the late 19th century: local injection of an anesthetic agent(s). 4 At the present time, the vast majority of ophthalmic procedures are performed using either the retrobulbar or peribulbar techniques of local anesthesia administration. Because of the small but not insignificant risks associated with both retrobulbar and peribulbar injections, and the convenience of orally administered pain medications, local anesthesia is not often used to achieve ocular analgesia in the immediate postoperative period. 5 Recently, a novel method for the delivery oflocal anes12 thesia during ophthalmic surgery has been described. • This method involves the retrobulbar irrigation of the anesthetic solution through a blunt-tipped catheter after the conjunctiva and Tenon's fascia are incised. Both the primary delivery of anesthetic agent(s) as well as the augmentation of a traditional retrobulbar or peribulbar block may be performed successfully using this technique. Because no injection and no needle is used, the theoretical risks of this procedure are limited to hypersensitivity reactions to the anesthetic agents. Bupivacaine hydrochloride is an anilide anesthetic agent that is related to lidocaine but has a much longer duration of action. 3 Since its introduction in the United States in the 1970s, it has been extensively tested in both ocular and nonocular settings. 6 •7 It has been shown in a

3

4

5

6

"Moderate"

"Severe"

"Worst Pain Ever"

1 7

0 4

0 0

prospective study to be safe and effective for scleral buckling surgery. 3 Bupivacaine's duration of action of up to 12 hours makes it an ideal medication for use in surgical procedures like scleral buckling, in which the bulk of the postoperative discomfort occurs within the first 24 hours. 3 Our study indicates that retrobulbar irrigation with bupivacaine hydrochloride 0. 75% provides effective pain relief in the majority of patients undergoing scleral buckling surgery. In addition, the use of such a retrobulbar irrigation appears safe in individuals without a history of sensitivity to local anesthetic agents. This method is also simple, convenient, and cost-effective, since in over 85% of the patients who received the retrobulbar irrigation, no parenteral pain medication was necessary after the surgery. Because intravenous or intramuscular delivery of postoperative pain medication was not necessary in these patients, no specialized nursing personnel were required to perform their postoperative care. One theoretical pitfall in using this technique is the possibility that the long-acting local anesthetic agent might mask the increasing ocular discomfort that often represents the first sign of postoperative complications such as elevated intraocular pressure, hemorrhagic choroidal detachment, or endophthalmitis. While we believe it is unlikely that the technique of retrobulbar bupivacaine irrigation should mask the pain associated with these complications to any more of a degree than narcotic analgesics, this possibility should be kept in mind when assessing postoperative complications. In such cases, objective data, rather than the patient's subjective pain level, should be relied upon. Another potential shortcoming of this technique is the theoretical possibility that enhancement of pain might actually occur as the anesthetic agent wears off. Such a "rebound" effect was not apparent in the patients in this study. We believe that surgeons who use the technique of retrobulbar bupivacaine irrigation will observe significantly less postoperative pain in their patients. Although this study only evaluated retrobulbar irrigation in patients undergoing general anesthesia, the method may be a useful adjunct for local anesthesia cases as well. Additionally, this method should have applicability for other ophthalmic procedures besides scleral buckling. Any patient undergoing an operation that includes a peritomy and incision of Tenon's fascia in which moderate to severe postoperative pain is anticipated (e.g,. enucleation, transconjunctival orbital procedures) may be a candidate for this method of postoperative pain relief. In light of the 517

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recent, strong trend to perform ophthalmic procedures on an outpatient basis, retrobulbar irrigation with a longacting anesthetic agent may prove to be a widely applicable means of decreasing postoperative discomfort.

REFERENCES 1. Mein CE, Flynn HW Jr. Augmentation of local anesthesia during retinal detachment surgery. Arch Ophthalmol1989; 107:1084.

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2. Mein CE, Woodcock MG. Local anesthesia for vitreoretinai surgery. Retina 1990; 10:47-9. 3. Hoiekamp TLR, Arribas NP, Boniuk I. Bupivacaine anesthesia in retinal detachment surgery. Arch Ophthalmol 1979; 97:109-11. 4. Feibel RM. Current concepts in retrobulbar anesthesia. Surv Ophthalmol1985; 30:102-10. 5. Knopf HLS. Periocular anesthesia for relief of pain. Ann Ophthalmol 1987; 19:181. 6. Moore DC, Bridenbaugh LD, Bridenbaugh PO, et al. Bupivacaine hydrochloride: a summary of investigational use in 3,274 cases. Anesth Analg 1971; 50:856-69. 7. Gills JP, Rudisill JE. Bupivacaine in cataract surgery. Ophthalmic Surg 1974; 5(4):67-70.

Retrobulbar bupivacaine irrigation for postoperative pain after scleral buckling surgery. A prospective study.

The authors conducted a prospective, randomized, double-masked clinical trial to determine if retrobulbar irrigation with bupivacaine hydrochloride 0...
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