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Retrobulbar block using pentothal as a sedative for ambulatory cataract surgery
Retrobulbar block using pentothal as a sedative for ambulatory cataract surgery Prem KC. Vindhya, M.D. John H. Sheets, M.D. Nalin H. Tolia, M.D. Lester J. Tomlinson, C.R.N.A. Odessa, Texas
ABSTRACT Cataract surgery comprises 80% to 85% of the surgical procedures performed at our ambulatory surgical center. We have developed a safe and effective method of sedation and amnesia fo." performing a retrobulbar block. We use sodium thiopental , administered intravenously, just prior to the block. We encourage the anesthesia departments of other facilities to consider this relatively simple blocking procedure for the comfort and safety of the patient.
injection, the anesthesiologist administers sodium thiopental, 2 mg to 3 mg/kg of body weight, as a bolus dose. Other modifying factors used in determining the dosage are listed in Table 1. The person administering the block stands on the side of the eye to be operated on while the anesthetist is on the other side (Figure 1). Once the effect of the thiopental is achieved, a retrobulbar injection using a 23-gauge needle is performed, entering the orbit at the junction oflateral onethird and medial two-thirds of the lower margin of the orbital rim.The anesthetist holds the chin up with one hand to prevent movement and maintain an adequate airway. The blocker injects 4 cc to 5 cc of the local anesthetic mixture.
Key "Vords: am nesia, intravenous sodium thiope ntal , regional eye block, r trobulbar block, sedation Fig. 1.
The goal of cataract surgery is to restore functional vision through a successful, comfortable procedure. This article presents a simple, safe way to provide good anesthesia and amnesia before the classic retrobulbar block. l We have performed more than 1,331 cases using this procedure. PROCEDURE A preanesthetic checklist is completed and the treatment and type of anesthesia to be administered is discussed with the patient. An intravenous of 5% dextrose with lactated Ringer's solution is started with a small bore angiocath (usually a 20 gauge). Blood pressure measurements and EKG monitoring are made throughout the procedure. A mixture containing 20 ml 2% lidocaine with epinephrine, 20 ml 0.5% bupivacaine hydrochloride (Marcaine®) and 1 ml hyaluronidase is prepared. Prior to the retrobulbar We thank Eric L. Wasserman, M.D., and Mary Ann Olsen for reviewing this manuscript. Reprint requests to Prem KC. Vindhya, M.D., Eyes of Texas, Inc., Route 1, Box 21OA, Odessa, Texas 79762.
J CATARACT
(Vindhya) Administration of the retrobulbar block: Patient is well relaxed, eye is in neutral position.
The EKG, blood pressure, and respirations are monitored throughout the block and every few minutes until the patient regains consciousness. Vital signs are then taken every five minutes, as in all anesthesia monitoring. The patients are transported to the operating room by wheelchair. At the completion of surgery the patient is returned by wheelchair to the recovery area. After a final vital sign and ambulation check, the patient is discharged, generally leaving the facility 15 to 20 minutes after the surgery is finished. The retrobulbar motor block usually lasts four to six hours. Patients generally do not need postoperative pain medication because Marcaine's action lasts up to ten hours. RESULTS The preretrobulbar block, sodium thiopental administration, has been used in 1,331 patients. Of these, 231 were second-time eye surgery patients. Not all had their first procedure performed in our facility. The majority of these patients were classified as ASA Class II to Class III. They ranged in age from 55 to 85 years.
REFRACT SURG-VOL 13, MAY 1987
321
Table 1. Factors used in determining sodium thiopental dosage. Dosage
Factors
1-2 mg/kg body weight
85 years Thin build Severe C.O.P.D.
2-3 mglkg body weight
Young adults Moderate to heavy build Alcoholics On C.N .S. depressants
Thirty-one of the 1,331 patients felt discomfort or pain during the block. They had received less than the average dose of sodium thiopental because of extreme age, chronic obstructive pulmonary disease, obesity, cardiac conditions, or a combination of two or more of these (Table 1). Within one minute of receiving thiopental, stage III plane 2 anesthesia was achieved. There were no significant changes in vital signs during any of the blocks and only 35 of the patients showed mild to moderate hypertensive episodes on completion of the block (Table 2). Of these 35 cases, 30 returned to normotensive condition spontaneously. The other five cases received hydralazine hydrochloride (5 mg to 15 mg). There were no changes in EKG. Four patients developed a brief coughing spell. Two patients complained of nausea, which was controlled with IV droperidol (0.625). Only one patient became agitated after receiving 100 mg of thiopental , but was easily quieted with an additional 75 mg. Forty-three patients (the majority of them in the younger age group) received an initial dosage of 2 mg to 3 mglkg body weight but required an additional dose of thiopental ranging from 1 mg to 2 mg/kg body weight to render them unconscious enough to block. All cases returned to a preanesthetic state within three to five minutes of the block.
achieves its effect with a rapid recovery time is desirable. The fentanyl, diazepam (Valium®) techniques take a long time for recovery.2 The nitrous oxide, oxygen technique takes five to 15 minutes for sedation and analgesia and it is awkward to move the anesthesia machine from bed to bed. 3 Sodium thiopental has several advantages over the fentanyl, Valium, or nitrous oxide, oxygen techniques, including ease, speed, better anesthesia, and a quicker recovery. It is our observation that during retrobulbar blocks, patients experience the highest degree of discomfort when the orbital septum is penetrated. We have found that sodium thiopental eliminates this painful memory. Regional blocks have long been within the purview of the anesthesiologist. A retrobulbar block should not be considered anything but a regional block and it is surprising how few anesthesiologists actually perform the procedure. Our personal experience with retrobulbar blocks using sodium thiopental sedation has been extremely rewarding and we encourage anesthesiologists and residents to participate in providing this special regional block more often. REFERENCES 1. Gills JP, Loyd TL: A technique of retrobulbar block with
paralysis of orbicularis oculi. Am Intra-Ocular Implant Soc] 9:339-340, 1983 2. Philip BK: Supplemental medication for ambulatory procedures under regional anesthesia. Anesth Analg 64:1117-1123, 1985 3. Corboy JM: Nitrous oxide analgesia for outpatient surgery. Am Intra-Ocular Implant Soc] 10:232-234, 1984
DISCUSSION In an ambulatory setting, to facilitate surgery and postoperative discharge an anesthesia protocol that Table 2. Reactions to sodium thiopental seen in 1,331 cases. Problems
Cases
Percentage
35
2.629
Atrial fibrillation
3
0.002
Cough
4
0.003
Nausea
2
0.001
Agitation
1
0.001
5
0.003
31
2.239
High blood pressure
Retrobulbar hemorrhage Discomfort during the block
322
J CATARACT REFRACT SURG-VOL
13, MAY 1987
ABSTRACT Cataract surgery comprises 80% to 85% of the surgical procedures performed at our ambulatory surgical center. We have developed a safe and effective method of sedation and amnesia fo." performing a retrobulbar block. We use sodium thiopental , administered intravenously, just prior to the block. We encourage the anesthesia departments of other facilities to consider this relatively simple blocking procedure for the comfort and safety of the patient.
injection, the anesthesiologist administers sodium thiopental, 2 mg to 3 mg/kg of body weight, as a bolus dose. Other modifying factors used in determining the dosage are listed in Table 1. The person administering the block stands on the side of the eye to be operated on while the anesthetist is on the other side (Figure 1). Once the effect of the thiopental is achieved, a retrobulbar injection using a 23-gauge needle is performed, entering the orbit at the junction oflateral onethird and medial two-thirds of the lower margin of the orbital rim.The anesthetist holds the chin up with one hand to prevent movement and maintain an adequate airway. The blocker injects 4 cc to 5 cc of the local anesthetic mixture.
Key "Vords: am nesia, intravenous sodium thiope ntal , regional eye block, r trobulbar block, sedation Fig. 1.
The goal of cataract surgery is to restore functional vision through a successful, comfortable procedure. This article presents a simple, safe way to provide good anesthesia and amnesia before the classic retrobulbar block. l We have performed more than 1,331 cases using this procedure. PROCEDURE A preanesthetic checklist is completed and the treatment and type of anesthesia to be administered is discussed with the patient. An intravenous of 5% dextrose with lactated Ringer's solution is started with a small bore angiocath (usually a 20 gauge). Blood pressure measurements and EKG monitoring are made throughout the procedure. A mixture containing 20 ml 2% lidocaine with epinephrine, 20 ml 0.5% bupivacaine hydrochloride (Marcaine®) and 1 ml hyaluronidase is prepared. Prior to the retrobulbar We thank Eric L. Wasserman, M.D., and Mary Ann Olsen for reviewing this manuscript. Reprint requests to Prem KC. Vindhya, M.D., Eyes of Texas, Inc., Route 1, Box 21OA, Odessa, Texas 79762.
J CATARACT
(Vindhya) Administration of the retrobulbar block: Patient is well relaxed, eye is in neutral position.
The EKG, blood pressure, and respirations are monitored throughout the block and every few minutes until the patient regains consciousness. Vital signs are then taken every five minutes, as in all anesthesia monitoring. The patients are transported to the operating room by wheelchair. At the completion of surgery the patient is returned by wheelchair to the recovery area. After a final vital sign and ambulation check, the patient is discharged, generally leaving the facility 15 to 20 minutes after the surgery is finished. The retrobulbar motor block usually lasts four to six hours. Patients generally do not need postoperative pain medication because Marcaine's action lasts up to ten hours. RESULTS The preretrobulbar block, sodium thiopental administration, has been used in 1,331 patients. Of these, 231 were second-time eye surgery patients. Not all had their first procedure performed in our facility. The majority of these patients were classified as ASA Class II to Class III. They ranged in age from 55 to 85 years.
REFRACT SURG-VOL 13, MAY 1987
321
Table 1. Factors used in determining sodium thiopental dosage. Dosage
Factors
1-2 mg/kg body weight
85 years Thin build Severe C.O.P.D.
2-3 mglkg body weight
Young adults Moderate to heavy build Alcoholics On C.N .S. depressants
Thirty-one of the 1,331 patients felt discomfort or pain during the block. They had received less than the average dose of sodium thiopental because of extreme age, chronic obstructive pulmonary disease, obesity, cardiac conditions, or a combination of two or more of these (Table 1). Within one minute of receiving thiopental, stage III plane 2 anesthesia was achieved. There were no significant changes in vital signs during any of the blocks and only 35 of the patients showed mild to moderate hypertensive episodes on completion of the block (Table 2). Of these 35 cases, 30 returned to normotensive condition spontaneously. The other five cases received hydralazine hydrochloride (5 mg to 15 mg). There were no changes in EKG. Four patients developed a brief coughing spell. Two patients complained of nausea, which was controlled with IV droperidol (0.625). Only one patient became agitated after receiving 100 mg of thiopental , but was easily quieted with an additional 75 mg. Forty-three patients (the majority of them in the younger age group) received an initial dosage of 2 mg to 3 mglkg body weight but required an additional dose of thiopental ranging from 1 mg to 2 mg/kg body weight to render them unconscious enough to block. All cases returned to a preanesthetic state within three to five minutes of the block.
achieves its effect with a rapid recovery time is desirable. The fentanyl, diazepam (Valium®) techniques take a long time for recovery.2 The nitrous oxide, oxygen technique takes five to 15 minutes for sedation and analgesia and it is awkward to move the anesthesia machine from bed to bed. 3 Sodium thiopental has several advantages over the fentanyl, Valium, or nitrous oxide, oxygen techniques, including ease, speed, better anesthesia, and a quicker recovery. It is our observation that during retrobulbar blocks, patients experience the highest degree of discomfort when the orbital septum is penetrated. We have found that sodium thiopental eliminates this painful memory. Regional blocks have long been within the purview of the anesthesiologist. A retrobulbar block should not be considered anything but a regional block and it is surprising how few anesthesiologists actually perform the procedure. Our personal experience with retrobulbar blocks using sodium thiopental sedation has been extremely rewarding and we encourage anesthesiologists and residents to participate in providing this special regional block more often. REFERENCES 1. Gills JP, Loyd TL: A technique of retrobulbar block with
paralysis of orbicularis oculi. Am Intra-Ocular Implant Soc] 9:339-340, 1983 2. Philip BK: Supplemental medication for ambulatory procedures under regional anesthesia. Anesth Analg 64:1117-1123, 1985 3. Corboy JM: Nitrous oxide analgesia for outpatient surgery. Am Intra-Ocular Implant Soc] 10:232-234, 1984
DISCUSSION In an ambulatory setting, to facilitate surgery and postoperative discharge an anesthesia protocol that Table 2. Reactions to sodium thiopental seen in 1,331 cases. Problems
Cases
Percentage
35
2.629
Atrial fibrillation
3
0.002
Cough
4
0.003
Nausea
2
0.001
Agitation
1
0.001
5
0.003
31
2.239
High blood pressure
Retrobulbar hemorrhage Discomfort during the block
322
J CATARACT REFRACT SURG-VOL
13, MAY 1987