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Low-molecular weight heparin administration after subarachnoid block
Regional Anesthesia and Pain Medicine 24(4): 375-377, 1999
Letters to the Editor
Kurien's Technique of Local Anesthetic Injection Into Fallopian Tubes
study by Tool et al., and I am in agreement with the authors w h e n they conclude that local anesthetic applications to the fallopian tubes significantly reduce immediate postoperative pain. The absence of significant relief with ketorolac also seems to rule out prostaglandin-mediated mechanisms in the etiology of this pain. That the significant improvement in postoperative pain scores in the bupivacaine group did not translate into decreased supplemental pain medication either in the recovery room or at h o m e is disconcerting. It seems reasonable to conclude that the short-lived action of bupivacaine is due to the limitations of dripping solutions onto tissue, most of which usually runs off into the general peritoneal cavity before it has had a chance to work. The actual injection of the mediLcation gets around this problem. This is probably even more relevant with the i m m i n e n t availability of bupivacaine-soaked microspheres with the promise of 4 8 - 7 2 hours of local anesthetic action, analogous to the sustained-release opioids. Dr. Charsley's suggestion of using the port on the silastic band applicator to apply the local anesthetic topically in morbidly obese patients, w h e n for technical reasons including inadequate length of spinal needles, injection of the tubes is not possible, is eminently practical and reasonable.
To the Editor: I was interested to read of Dr. Kurien's technique of local anesthetic injection into fallopian tubes for the relief of pain after laparoscopic tubal ligation with clips. Indeed, the observation that the n e w e r methods of sterilization with clips or bands cause more pain than tubal occlusion with electrocoagulation prompted a study to develop a technique using local anesthetic in our own institution. I would like to draw Dr. Kurien's attention to a study by Tool et al. The authors of this study also applied local anesthetic to the fallopian tubes. The bupivacaine or normal saline was applied to the fallopian tube by injection through a port on the silastic band applicator or by using an 18-gauge, 3.5-cm spinal needle introduced through a separate midline puncture site. The solution, however, was merely dripped over each fallopian tube, and the silastic bands then applied in the usual manner. This study found significantly decreased postoperative pain scores with topical bupivacaine compared with those pain scores with placebo. I would suggest that the use of the port on the silastic band applicator to apply the local anesthetic topically could be the m e t h o d of choice for the morbidly obese where, as Dr. Kurien points out, the length of the spinal needle might be inadequate for the purpose of injecting the tube itself.
K. Mathai Kurien, M.D.
Department of Anesthesiology Thomas Jefferson University Hospital Philadelphia, Pennsylvania
M. M. Charsley, M.D.
Department of Anesthesiology University of New Mexico Albuquerque, New Mexico
Accepted for publication January 25, 1999.
References Low-Molecular Weight Heparin Administration After Subarachnoid Block
1. Tool AL, Kammerer-Doak DN, Nguyen CM, Cousin MO, Charsley MM. Postoperative pain relief tollowing laparoscopic tubal sterilization with silastic bands. Obstet Gynecol 1997: 90: 731-734.
To the Editor: We c o m m e n d the American Society of Regional Anesthesia for convening its Consensus Conference on Neuraxial Block and Anticoagulation. Given the high and devastating risk of epidural hematoma, coupled with the general paucity of available data, the conferees performed an admirable service for anesthesiologists and their patients. Drs. Horlocker and Wedel's comprehensive review (1) of the risks associated with concurrent usage of low-molecular weight heparins (LMWH) in patients receiving neuraxial block was particular]Ly well conceived. We are, however, puzzled by one issue. The authors emphasize the previously
Accepted for publication November 5, 1998.
Reply to Dr. Charsley's Letter Regarding Kurien's Technique of Local Anesthetic Injection Into Fallopian Tubes To the Editor: Thank you very m u c h for the opportunity to respond to the letter by Dr. Charsley. I was able to review the
375
376
RegionalAnesthesiaand Pain Medicine Vol. 24 No. 4 July-August 1999
underappreciated risk of bleeding following epidural catheter removal, and thus their recommendation to wait at least 2 hours before commencing or restarting LMWH administration seems logically appropriate. However, the recommendation to not initiate LMWH until at least 24 hours after subarachnoid block seems discordant with the epidural catheter recommendation. Why should the risk of bleeding following atraumatic, small-gauge spinal needle insertion be more significant than that associated with removal of a much larger catheter? We are curious to understand if the Consensus Conference made their subarachnoid block recommendation based on data, current manufacturer's recommendations, or some other factor. If not based on substantive data, we suggest that the next Consensus Conference consider bringing these seemingly disparate recommendations into closer concordance. Again, our congratulations to ASRA and the Consensus Conference participants for distilling relevant information into a practical format. Joseph M. Neal, M,D. Dan J. Kopacz, M.D.
The Mason Clinic Seattle, Washington References
1. Horlocker Tr, Wedel DJ. Neuraxial block and tow-molecular-weight heparin: Balancing perioperative analgesia and thromboprophylaxis. Reg Anesth Pain Med 1998: 23: 164-177. Accepted for publication December 23, I998.
Reply to Drs. Neal and Kopacz Regarding Low-Molecular Weight Heparin Administration After Subarachnoid Block To the Editor: We appreciate the thoughtful insights of Drs. Neal and Kopacz concerning the issue of early postoperative dosing of low-molecular weight heparin (LMWH) after uneventful spinal anesthesia. The risk of spinal h e m a t o m a has been reported by multiple investigators to be less with spinal anesthesia compared with continuous epidural anesthesia. For example, Tryba (1) estimated the overall incidence to be 1 in 220,000 spinal anesthetics compared to 1 in 150,000 epidural anesthetics. Perioperative administration of LMWH increased the risk substantially for both neuraxial techniques. The reporting rates of spinal hematoma, based on approximations of LMWH utilization and neuraxial block prevalence, were estimated to be 1 in 40,800 patients undergoing spinal anesthesia and 1 in 3,100 patients receiving postoperative epidural analgesia (2). Several factors m a y have contributed to the development of spinal h e m a t o m a among these patients, including traumatic or difficult needle placement, concomitant administration of antiplatelet medications, and early postoperative administration of LMWH (3).
Still, Drs. Neal and Kopacz raise an excellent point in their letter. It may be possible to safely administer LMWH 12 hours postoperatively (the earliest recommended timing of first LMWH dose) in a select group of patients having atraumatic spinal anesthesia, provided that no additional medications affecting coagulation are given. However, this deceptively simple change in the recommendations may be difficult to apply in actual clinical practice where communication between the anesthesiologist and surgical team is often not optimal. Attention must be given so that LMWH is not administered in the immediate postoperative period, yet with many "standard postop surgical orders," drug delivery typically occurs at 7 - 8 V.M., regardless of actual timing of needle placement. Some patients would be excluded for early postoperative dosing because of traumatic needle insertion. A previous study reported blood present during needle placement in 18% of patients undergoing spinal anesthesia (4). In reality, a limited number of patients would be candidates for same-day LMWH administration. Perhaps most importantly, consistent recommendations for spinal and epidural anesthesia allow simplicity in the management of these patients. This approach is validated by the Canadian experience. In Canada, LMWH thromboprophylaxis is widespread, but only a few spinal hematomas have been reported. Although it is difficult to determine for certain why the incidence appears to be lower in Canada than in the United States despite identical dosage regimens, one possible explanation is that many Canadian anesthesiologists and their surgical colleagues delay administration of LMWH until the day after surgery. In conclusion, the rationale for similar recommendations following spinal or epidural anesthesia is based on the drug labeling, evaluation of the case reports of spinal hematoma, and the complexities of current medical practice. Although the recommendations m a y be conservative, spinal h e m a t o m a is a catastrophic complication of neuraxial block, and the members of the consensus conference wish to err on the side of patient safety. However, even the most conservative recommendations will not eliminate the risk of spinal hematoma. Education of the entire patient care team is critical for early diagnosis and improved neurologic outcome. Terese T. Horlocker, M.D. Denise J. Wedel, M.D.
Department of Anesthesiology Mayo Clinic Rochester, Minnesota References
l. Tryba M. Epidural regional anesthesia and low molecular heparin: Pro (German). An~sthesiol Intensivmed Notfallmed Schmerzther I993: 28: 179-181. 2. Schroeder DR. Statistics: Detecting a rare adverse drug reaction using spontaneous reports. Reg Anesth Pain Med 1998: 23: i83-189. 3. Horlocker TT, Wedel DJ. Neuraxial block and low-molecular weight heparin: Balancing perioperative analgesia and thromboprophylaxis. Reg Anesth Pain Med 1998: 23: 164-177. 4. Horlocker TT, Wedel DJ, Schroeder DR, Rose SH, Elliott BA,
Letters to the Editor
Kurien's Technique of Local Anesthetic Injection Into Fallopian Tubes
study by Tool et al., and I am in agreement with the authors w h e n they conclude that local anesthetic applications to the fallopian tubes significantly reduce immediate postoperative pain. The absence of significant relief with ketorolac also seems to rule out prostaglandin-mediated mechanisms in the etiology of this pain. That the significant improvement in postoperative pain scores in the bupivacaine group did not translate into decreased supplemental pain medication either in the recovery room or at h o m e is disconcerting. It seems reasonable to conclude that the short-lived action of bupivacaine is due to the limitations of dripping solutions onto tissue, most of which usually runs off into the general peritoneal cavity before it has had a chance to work. The actual injection of the mediLcation gets around this problem. This is probably even more relevant with the i m m i n e n t availability of bupivacaine-soaked microspheres with the promise of 4 8 - 7 2 hours of local anesthetic action, analogous to the sustained-release opioids. Dr. Charsley's suggestion of using the port on the silastic band applicator to apply the local anesthetic topically in morbidly obese patients, w h e n for technical reasons including inadequate length of spinal needles, injection of the tubes is not possible, is eminently practical and reasonable.
To the Editor: I was interested to read of Dr. Kurien's technique of local anesthetic injection into fallopian tubes for the relief of pain after laparoscopic tubal ligation with clips. Indeed, the observation that the n e w e r methods of sterilization with clips or bands cause more pain than tubal occlusion with electrocoagulation prompted a study to develop a technique using local anesthetic in our own institution. I would like to draw Dr. Kurien's attention to a study by Tool et al. The authors of this study also applied local anesthetic to the fallopian tubes. The bupivacaine or normal saline was applied to the fallopian tube by injection through a port on the silastic band applicator or by using an 18-gauge, 3.5-cm spinal needle introduced through a separate midline puncture site. The solution, however, was merely dripped over each fallopian tube, and the silastic bands then applied in the usual manner. This study found significantly decreased postoperative pain scores with topical bupivacaine compared with those pain scores with placebo. I would suggest that the use of the port on the silastic band applicator to apply the local anesthetic topically could be the m e t h o d of choice for the morbidly obese where, as Dr. Kurien points out, the length of the spinal needle might be inadequate for the purpose of injecting the tube itself.
K. Mathai Kurien, M.D.
Department of Anesthesiology Thomas Jefferson University Hospital Philadelphia, Pennsylvania
M. M. Charsley, M.D.
Department of Anesthesiology University of New Mexico Albuquerque, New Mexico
Accepted for publication January 25, 1999.
References Low-Molecular Weight Heparin Administration After Subarachnoid Block
1. Tool AL, Kammerer-Doak DN, Nguyen CM, Cousin MO, Charsley MM. Postoperative pain relief tollowing laparoscopic tubal sterilization with silastic bands. Obstet Gynecol 1997: 90: 731-734.
To the Editor: We c o m m e n d the American Society of Regional Anesthesia for convening its Consensus Conference on Neuraxial Block and Anticoagulation. Given the high and devastating risk of epidural hematoma, coupled with the general paucity of available data, the conferees performed an admirable service for anesthesiologists and their patients. Drs. Horlocker and Wedel's comprehensive review (1) of the risks associated with concurrent usage of low-molecular weight heparins (LMWH) in patients receiving neuraxial block was particular]Ly well conceived. We are, however, puzzled by one issue. The authors emphasize the previously
Accepted for publication November 5, 1998.
Reply to Dr. Charsley's Letter Regarding Kurien's Technique of Local Anesthetic Injection Into Fallopian Tubes To the Editor: Thank you very m u c h for the opportunity to respond to the letter by Dr. Charsley. I was able to review the
375
376
RegionalAnesthesiaand Pain Medicine Vol. 24 No. 4 July-August 1999
underappreciated risk of bleeding following epidural catheter removal, and thus their recommendation to wait at least 2 hours before commencing or restarting LMWH administration seems logically appropriate. However, the recommendation to not initiate LMWH until at least 24 hours after subarachnoid block seems discordant with the epidural catheter recommendation. Why should the risk of bleeding following atraumatic, small-gauge spinal needle insertion be more significant than that associated with removal of a much larger catheter? We are curious to understand if the Consensus Conference made their subarachnoid block recommendation based on data, current manufacturer's recommendations, or some other factor. If not based on substantive data, we suggest that the next Consensus Conference consider bringing these seemingly disparate recommendations into closer concordance. Again, our congratulations to ASRA and the Consensus Conference participants for distilling relevant information into a practical format. Joseph M. Neal, M,D. Dan J. Kopacz, M.D.
The Mason Clinic Seattle, Washington References
1. Horlocker Tr, Wedel DJ. Neuraxial block and tow-molecular-weight heparin: Balancing perioperative analgesia and thromboprophylaxis. Reg Anesth Pain Med 1998: 23: 164-177. Accepted for publication December 23, I998.
Reply to Drs. Neal and Kopacz Regarding Low-Molecular Weight Heparin Administration After Subarachnoid Block To the Editor: We appreciate the thoughtful insights of Drs. Neal and Kopacz concerning the issue of early postoperative dosing of low-molecular weight heparin (LMWH) after uneventful spinal anesthesia. The risk of spinal h e m a t o m a has been reported by multiple investigators to be less with spinal anesthesia compared with continuous epidural anesthesia. For example, Tryba (1) estimated the overall incidence to be 1 in 220,000 spinal anesthetics compared to 1 in 150,000 epidural anesthetics. Perioperative administration of LMWH increased the risk substantially for both neuraxial techniques. The reporting rates of spinal hematoma, based on approximations of LMWH utilization and neuraxial block prevalence, were estimated to be 1 in 40,800 patients undergoing spinal anesthesia and 1 in 3,100 patients receiving postoperative epidural analgesia (2). Several factors m a y have contributed to the development of spinal h e m a t o m a among these patients, including traumatic or difficult needle placement, concomitant administration of antiplatelet medications, and early postoperative administration of LMWH (3).
Still, Drs. Neal and Kopacz raise an excellent point in their letter. It may be possible to safely administer LMWH 12 hours postoperatively (the earliest recommended timing of first LMWH dose) in a select group of patients having atraumatic spinal anesthesia, provided that no additional medications affecting coagulation are given. However, this deceptively simple change in the recommendations may be difficult to apply in actual clinical practice where communication between the anesthesiologist and surgical team is often not optimal. Attention must be given so that LMWH is not administered in the immediate postoperative period, yet with many "standard postop surgical orders," drug delivery typically occurs at 7 - 8 V.M., regardless of actual timing of needle placement. Some patients would be excluded for early postoperative dosing because of traumatic needle insertion. A previous study reported blood present during needle placement in 18% of patients undergoing spinal anesthesia (4). In reality, a limited number of patients would be candidates for same-day LMWH administration. Perhaps most importantly, consistent recommendations for spinal and epidural anesthesia allow simplicity in the management of these patients. This approach is validated by the Canadian experience. In Canada, LMWH thromboprophylaxis is widespread, but only a few spinal hematomas have been reported. Although it is difficult to determine for certain why the incidence appears to be lower in Canada than in the United States despite identical dosage regimens, one possible explanation is that many Canadian anesthesiologists and their surgical colleagues delay administration of LMWH until the day after surgery. In conclusion, the rationale for similar recommendations following spinal or epidural anesthesia is based on the drug labeling, evaluation of the case reports of spinal hematoma, and the complexities of current medical practice. Although the recommendations m a y be conservative, spinal h e m a t o m a is a catastrophic complication of neuraxial block, and the members of the consensus conference wish to err on the side of patient safety. However, even the most conservative recommendations will not eliminate the risk of spinal hematoma. Education of the entire patient care team is critical for early diagnosis and improved neurologic outcome. Terese T. Horlocker, M.D. Denise J. Wedel, M.D.
Department of Anesthesiology Mayo Clinic Rochester, Minnesota References
l. Tryba M. Epidural regional anesthesia and low molecular heparin: Pro (German). An~sthesiol Intensivmed Notfallmed Schmerzther I993: 28: 179-181. 2. Schroeder DR. Statistics: Detecting a rare adverse drug reaction using spontaneous reports. Reg Anesth Pain Med 1998: 23: i83-189. 3. Horlocker TT, Wedel DJ. Neuraxial block and low-molecular weight heparin: Balancing perioperative analgesia and thromboprophylaxis. Reg Anesth Pain Med 1998: 23: 164-177. 4. Horlocker TT, Wedel DJ, Schroeder DR, Rose SH, Elliott BA,