Clinical Orthopaedics and Related Research®
Clin Orthop Relat Res DOI 10.1007/s11999-013-3452-2
A Publication of The Association of Bone and Joint Surgeons®
SYMPOSIUM: PERIOPERATIVE PAIN MANAGEMENT IN ORTHOPAEDIC SURGERY
Lateralizing Epidural Catheter Placement as Evidenced by Electrical Stimulation Nigel E. Sharrock BMedSci, MB, ChB, George Go BS
Ó The Association of Bone and Joint Surgeons1 2014
Abstract Background Epidural steroids are more effective if administered in the anterolateral epidural space. It follows that the ability to administer local anesthetics in the ipsilateral anterolateral epidural space should likewise improve their efficacy for postoperative epidural analgesia. Questions/purposes We determined whether epidural catheters can be reliably placed in the ipsilateral anterolateral epidural space using the paramedian approach. Motor responses elicited by electrical stimulation were used to identify lateralization. We further assessed what angle of needle insertion resulted in successful catheter placement. Methods Epidural anesthesia was performed in 68 patients undergoing total joint arthroplasty using the paramedian approach. FDA-approved electrical stimulating
Each author certifies that he or she, or a member of his or her immediate family, has no funding or commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. Clinical Orthopaedics and Related Research neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDA approval status, of any drug or device before clinical use. Each author certifies that his or her institution approved the human protocol for this investigation, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation in the study was obtained. N. E. Sharrock (&), G. Go Department of Anesthesiology, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA e-mail: [email protected]
catheters were utilized, and the muscle response elicited was recorded with each centimeter of advancement of the catheter. Digital photographs were taken to determine the angle of needle entry. Results Using the paramedian approach, an ipsilateral twitch was noted in 66 of the 68 patients (two had no response). With advancement of the catheter (2–5 cm), the twitch remained ipsilateral in 56 but disappeared in 12. The mean angle of the epidural needle was 40° to the midline. All patients had successful epidural anesthesia as evidenced by no response to surgical incision. Conclusions Epidural catheters can be reliably placed onto the side of surgery using the paramedian approach. This provides the opportunity to more selectively administer epidural local anesthetics. Level of Evidence Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.
Introduction Nerve roots pass through the anterolateral epidural space before exiting the intervertebral foramina. In theory, optimal delivery of any drug to the nerve roots requires placement of a needle or catheter in close proximity to the specific nerve roots, rather than just anywhere in the epidural space. In chronic pain management, epidural steroids have been shown to selectively spread in the lateral epidural space if administered via a transforaminal approach in volumes of 2 to 5 mL [1, 3]. Furthermore, Candido et al. [4] have demonstrated that lateral epidural injection of steroids provides superior pain control compared to midline epidural injection. It follows that placement of epidural catheters in the anterolateral epidural space should provide
123
Clinical Orthopaedics and Related Research1
Sharrock and Go
superior delivery of local anesthetic to the necessary nerve roots. Epidural and spinal anesthesia is typically performed using the midline approach, which provides no ability to direct the catheter [2]. With the paramedian approach, the needle enters the epidural space at an angle, suggesting that it may be possible to lateralize the catheter. To verify ipsilateral location, fluoroscopic verification of radiopaque dye is the logical option, but it is not feasible in the perioperative setting. An alternative is electrical stimulation of nerve roots, which was initially described by Tsui et al. [11]. This technique has been used to verify correct epidural placement perioperatively but not specifically used to identify lateralization of the catheters [6, 11, 12]. We therefore determined (1) whether epidural catheters can be placed in the ipsilateral anterolateral epidural space using the paramedian approach. A unilateral motor response using electrical stimulation was utilized to identify lateralization. We further assessed (2) what angle of needle insertion resulted in successful catheter placement.
Patients and Methods After institutional review board approval, 68 patients undergoing lower-extremity surgery under epidural anesthesia consented to participate in this prospective observational trial (Table 1). Exclusion criteria included patients with prior lumbar spine surgery, patients with bleeding disorders, patients receiving anticoagulant therapy, or patients with a prior history of epidural infection. Patients were included independent of BMI (mean ± SD, 28 ± 5 kg/m2; range, 19–42 kg/m2). Mean age was 62 ± 11 (range, 23–85 years). All anesthetics were performed by a single anesthesiologist (NES).
In all 68 patients, an attempt was made to advance the catheter onto the side of surgery using the paramedian approach. Epidural placement (based on clinical estimation and not imaging) was from T12-L1 to L3-L4 interspaces (L2-L3 or L3-L4 was utilized for patients undergoing TKA and L1-L2 or T12-L1 for THA) (Table 1). With the paramedian approach, the site of needle entry was 2 to 3 mm lateral to the spine, just caudad to the interspace. A 17-gauge Tuohy needle was advanced until the lamina was contacted, and then the needle was redirected cephalad and medially off the rostral edge of the lamina into the ligamentum flavum to enter the epidural space close to the midline. Epidural entry was identified by loss of resistance to fluid. A plastic housing of the Tuohy needle was placed along the midline by palpating the lumbar spines. The angle of the needle to the midline was then assessed using a photograph taken with a digital camera, and the angulation of the needle was subsequently measured (Fig. 1). An FDA-approved electrical stimulating catheter (Arrow StimuCathTM Continuous Nerve Block Procedure Kit; Arrow International, Reading, PA, USA) was then advanced into the epidural space using a current of 1 millisecond at 2.5 mA at 2 Hz [5]. Motor responses were assessed with each centimeter of advancement of the catheter and verified by video. Muscle twitches were characterized by whether they were ipsilateral (ie, on the side of surgery) or contralateral to the side of surgery. Catheters were advanced up to 4 cm. Thereafter, local anesthetic was injected in incremental doses via the stimulating catheter to provide surgical anesthesia. The following recordings were made: (1) the interspace used; (2) the degree of angulation of the needle to the midline; (3) the presence and absence of a muscle twitch; and (4) whether the twitch was ipsilateral or contralateral.
Table 1. Patient demographics, site of epidural injection, and needle angle (n = 68)
Results
Variable
Using the paramedian approach, successful catheter placement was achieved reliably, based on ipsilateral motor twitches appearing in 66 of the 68 patients (two had no response). In only one patient did the twitch change from ipsilateral to contralateral with advancing the catheter. In two patients, the twitch changed from ipsilateral to bilateral, suggesting anterior migration of the catheter. The initial twitch was noted when advancing the catheter by 1 cm in 53 of 68 patients, by 2 cm in a further 10 patients, and by 3 cm in two patients. In 12 of 66 patients, the responses disappeared with further advancement of the catheter and one became contralateral at 3 cm. In 38 patients, the twitch changed from one motor response to a more proximal one, suggesting a stimulation of a more rostral nerve root as the
Paramedian (n = 68)
Age (years)*
62 ± 11
Height (cm)* Weight (kg)*
170 ± 4 81 ± 21
BMI (kg/m2)*
28 ± 5
Epidural placement (number of patients) T12-L1
16
L1-L2
20
L2-L3
9
L3-L4
23
Angle of needle (°)
40 (17–67)
* Values are expressed as mean ± SD; values are expressed as mean, with range in parentheses.
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Lateralizing Epidural Catheter Placement
Fig. 1 Angulation of the needle is measured using Adobe1 Photoshop1 (Adobe Systems, Inc, San Jose, CA, USA).
catheter advanced up the anterior gutter on the ipsilateral side. In all 68 patients, successful epidural anesthesia was obtained as evidenced by no response to surgical incision. The mean angle of epidural entry was 40° (range, 17°–67°) (Table 1).
Discussion The possibility that epidural catheters can be reliably lateralized is contrary to traditional teaching. Bromage [2] put it well when he stated: ‘‘It is not easy to predict the course a catheter will take once the epidural space has been penetrated.’’ This may be true when performing epidural anesthesia using the midline approach, but this study demonstrated that the lateralization of epidural catheters can be reliably achieved using the paramedian approach. Ipsilateral localization occurred in 66 of 68 patients. In no patient was a contralateral twitch noted. The angle of epidural entry was 40° (range, 17°–60°) to the midline. This is a significant medial angulation but one that consistently led to ipsilateral lateralization. A less acute angle may not provide such consistency. There are several limitations to this study. Firstly, the physical characteristics of epidural catheters vary. The stimulating catheter is fairly flexible. Whether the slightly more rigid nonstimulating catheter can be lateralized as reliably is unknown. Even though electrical stimulation verifies lateralization, spread of local anesthetics from multihole catheters may be less predictable. Secondly, the routine use of electrical stimulation to verify epidural entry has been debated [6] since it was first described in 1998 [11]. In two of our 68 patients, no twitch was elicited, yet successful epidural anesthetic was obtained. In the senior author’s (NES) hands, this technique offers no added
advantage over conventional signs (loss of resistance, etc). In addition, it is more expensive and entails more setup time. This study did not utilize the midline approach, the most commonly used approach in epidural anesthesia as the senior author has used the paramedian approach exclusively since 1977 to avoid equivocal signs of loss of resistance [9]. Finally, the dose of epidural analgesia may need to be changed if catheters can provide more targeted drug delivery. At one time, epidural analgesia had been considered the gold standard for postoperative analgesia, but its use has dwindled for a number of reasons, including a high rate of unreliability [8] and side effects [7, 10, 13]. Typically, epidural catheters are placed using the midline approach, wherein there is no control over catheter placement [2]. Catheters are likely to lie in the contralateral epidural space contributing to ineffective analgesia and side effects, including contralateral leg numbness and weakness [10, 13]. This study suggests that epidural analgesia could be improved by using the paramedian approach to selectively administer postoperative epidural analgesia, thereby reducing the likelihood of side effects and optimizing local anesthetic/pain control delivery. Our study suggests that the majority of the catheters remained ipsilateral as the catheter was advanced because the twitch remained the same or changed in motor response character the majority of the time. However, in 12 of 66 patients, the twitch disappeared with advancement of the catheter beyond 2 cm. Whether the catheter had passed more posteriorly is unknown. This suggests that catheters should be advanced no more than 2 to 4 cm to preserve ipsilateral placement. It is assumed in this study that a twitch meant that the catheter was in close proximity to a nerve root in the anterolateral epidural space. This was a feasibility study to determine whether lateralizing epidural catheter could be performed as evidenced by electrical stimulation. There was no evidence that lateralizing the epidural catheter improved surgical anesthesia, as the doses used were large (25–30 mL). However, it is possible that lateralizing the epidural catheter may enable lower doses of anesthetic to be administered for anesthesia. In conclusion, this study demonstrated that lateralization of epidural catheters is feasible using the paramedian approach, which should optimize the quality of epidural analgesia and reduce the likelihood of side effects.
References 1. Botwin KP, Natalicchio J, Hanna A. Fluoroscopic guided lumbar interlaminar epidural injections: a prospective evaluation of epidurography contrast patterns and anatomical review of the epidural space. Pain Physician. 2004;7:77–80.
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Clinical Orthopaedics and Related Research1
Sharrock and Go 2. Bromage PR. Epidural Analgesia. Philadelphia, PA: WB Saunders; 1978:220. 3. Candido KD, Raghavendra MS, Chinthagada M, Badiee S, Trepashko DW. A prospective evaluation of iodinated contrast flow patterns with fluoroscopically guided lumbar epidural steroid injections: the lateral parasagittal interlaminar epidural approach versus the transforaminal epidural approach. Anesth Analg. 2008;106:638–644. 4. Candido KD, Rana MV, Sauer R, Chupatanakul L, Tharian A, Vasic V, Knezevic NN. Concordant pressure paresthesia during interlaminar lumbar epidural steroid injections correlates with pain relief in patients with unilateral radicular pain. Pain Physician. 2013;16:497–511. 5. Chan SY, De la Cuadra Fontaine JC, Doan J, Tran de QH. Stimulating cervical epidural catheter. Anesth Analg. 2006;102:1910. 6. Forster JG, Niemi TT, Salmenpera MT, Ikonen S, Rosenberg PH. An evaluation of the epidural catheter position by epidural nerve stimulation in conjunction with continuous epidural analgesia in adult surgical patients. Anesth Analg. 2009;108:351–358. 7. Liu SS, Bae JJ, Bieltz M, Wukovits B, Ma Y. A prospective survey of patient-controlled epidural analgesia with bupivacaine and clonidine after total hip replacement: a pre- and postchange
123
8. 9.
10.
11.
12.
13.
comparison with bupivacaine and hydromorphone in 1,000 patients. Anesth Analg. 2011;113:1213–1217. Rawal N. Epidural technique for postoperative pain: gold standard no more? Reg Anesth Pain Med. 2012;37:310–317. Sharrock NE. Recordings of, and an anatomical explanation for, false positive loss of resistance during lumbar extradural analgesia. Br J Anaesth. 1979;51:253–258. Singelyn FJ, Deyaert M, Joris D, Pendeville E, Gouverneur JM. Effects of intravenous patient-controlled analgesia with morphine, continuous epidural analgesia, and continuous three-in-one block on postoperative pain and knee rehabilitation after unilateral total knee arthroplasty. Anesth Analg. 1998;87:88–92. Tsui BC, Gupta S, Finucane B. Confirmation of epidural catheter placement using nerve stimulation. Can J Anaesth. 1998;45:640– 644. Tsui BC, Wagner A, Cave D, Seal R. Threshold current for an insulated epidural needle in pediatric patients. Anesth Analg. 2004;99:694–696. Zaric D, Boysen K, Christiansen C, Christiansen J, Stephensen S, Christensen B. A comparison of epidural analgesia with combined continuous femoral-sciatic nerve blocks after total knee replacement. Anesth Analg. 2006;102:1240–1246.
Clin Orthop Relat Res DOI 10.1007/s11999-013-3452-2
A Publication of The Association of Bone and Joint Surgeons®
SYMPOSIUM: PERIOPERATIVE PAIN MANAGEMENT IN ORTHOPAEDIC SURGERY
Lateralizing Epidural Catheter Placement as Evidenced by Electrical Stimulation Nigel E. Sharrock BMedSci, MB, ChB, George Go BS
Ó The Association of Bone and Joint Surgeons1 2014
Abstract Background Epidural steroids are more effective if administered in the anterolateral epidural space. It follows that the ability to administer local anesthetics in the ipsilateral anterolateral epidural space should likewise improve their efficacy for postoperative epidural analgesia. Questions/purposes We determined whether epidural catheters can be reliably placed in the ipsilateral anterolateral epidural space using the paramedian approach. Motor responses elicited by electrical stimulation were used to identify lateralization. We further assessed what angle of needle insertion resulted in successful catheter placement. Methods Epidural anesthesia was performed in 68 patients undergoing total joint arthroplasty using the paramedian approach. FDA-approved electrical stimulating
Each author certifies that he or she, or a member of his or her immediate family, has no funding or commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. Clinical Orthopaedics and Related Research neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDA approval status, of any drug or device before clinical use. Each author certifies that his or her institution approved the human protocol for this investigation, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation in the study was obtained. N. E. Sharrock (&), G. Go Department of Anesthesiology, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA e-mail: [email protected]
catheters were utilized, and the muscle response elicited was recorded with each centimeter of advancement of the catheter. Digital photographs were taken to determine the angle of needle entry. Results Using the paramedian approach, an ipsilateral twitch was noted in 66 of the 68 patients (two had no response). With advancement of the catheter (2–5 cm), the twitch remained ipsilateral in 56 but disappeared in 12. The mean angle of the epidural needle was 40° to the midline. All patients had successful epidural anesthesia as evidenced by no response to surgical incision. Conclusions Epidural catheters can be reliably placed onto the side of surgery using the paramedian approach. This provides the opportunity to more selectively administer epidural local anesthetics. Level of Evidence Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.
Introduction Nerve roots pass through the anterolateral epidural space before exiting the intervertebral foramina. In theory, optimal delivery of any drug to the nerve roots requires placement of a needle or catheter in close proximity to the specific nerve roots, rather than just anywhere in the epidural space. In chronic pain management, epidural steroids have been shown to selectively spread in the lateral epidural space if administered via a transforaminal approach in volumes of 2 to 5 mL [1, 3]. Furthermore, Candido et al. [4] have demonstrated that lateral epidural injection of steroids provides superior pain control compared to midline epidural injection. It follows that placement of epidural catheters in the anterolateral epidural space should provide
123
Clinical Orthopaedics and Related Research1
Sharrock and Go
superior delivery of local anesthetic to the necessary nerve roots. Epidural and spinal anesthesia is typically performed using the midline approach, which provides no ability to direct the catheter [2]. With the paramedian approach, the needle enters the epidural space at an angle, suggesting that it may be possible to lateralize the catheter. To verify ipsilateral location, fluoroscopic verification of radiopaque dye is the logical option, but it is not feasible in the perioperative setting. An alternative is electrical stimulation of nerve roots, which was initially described by Tsui et al. [11]. This technique has been used to verify correct epidural placement perioperatively but not specifically used to identify lateralization of the catheters [6, 11, 12]. We therefore determined (1) whether epidural catheters can be placed in the ipsilateral anterolateral epidural space using the paramedian approach. A unilateral motor response using electrical stimulation was utilized to identify lateralization. We further assessed (2) what angle of needle insertion resulted in successful catheter placement.
Patients and Methods After institutional review board approval, 68 patients undergoing lower-extremity surgery under epidural anesthesia consented to participate in this prospective observational trial (Table 1). Exclusion criteria included patients with prior lumbar spine surgery, patients with bleeding disorders, patients receiving anticoagulant therapy, or patients with a prior history of epidural infection. Patients were included independent of BMI (mean ± SD, 28 ± 5 kg/m2; range, 19–42 kg/m2). Mean age was 62 ± 11 (range, 23–85 years). All anesthetics were performed by a single anesthesiologist (NES).
In all 68 patients, an attempt was made to advance the catheter onto the side of surgery using the paramedian approach. Epidural placement (based on clinical estimation and not imaging) was from T12-L1 to L3-L4 interspaces (L2-L3 or L3-L4 was utilized for patients undergoing TKA and L1-L2 or T12-L1 for THA) (Table 1). With the paramedian approach, the site of needle entry was 2 to 3 mm lateral to the spine, just caudad to the interspace. A 17-gauge Tuohy needle was advanced until the lamina was contacted, and then the needle was redirected cephalad and medially off the rostral edge of the lamina into the ligamentum flavum to enter the epidural space close to the midline. Epidural entry was identified by loss of resistance to fluid. A plastic housing of the Tuohy needle was placed along the midline by palpating the lumbar spines. The angle of the needle to the midline was then assessed using a photograph taken with a digital camera, and the angulation of the needle was subsequently measured (Fig. 1). An FDA-approved electrical stimulating catheter (Arrow StimuCathTM Continuous Nerve Block Procedure Kit; Arrow International, Reading, PA, USA) was then advanced into the epidural space using a current of 1 millisecond at 2.5 mA at 2 Hz [5]. Motor responses were assessed with each centimeter of advancement of the catheter and verified by video. Muscle twitches were characterized by whether they were ipsilateral (ie, on the side of surgery) or contralateral to the side of surgery. Catheters were advanced up to 4 cm. Thereafter, local anesthetic was injected in incremental doses via the stimulating catheter to provide surgical anesthesia. The following recordings were made: (1) the interspace used; (2) the degree of angulation of the needle to the midline; (3) the presence and absence of a muscle twitch; and (4) whether the twitch was ipsilateral or contralateral.
Table 1. Patient demographics, site of epidural injection, and needle angle (n = 68)
Results
Variable
Using the paramedian approach, successful catheter placement was achieved reliably, based on ipsilateral motor twitches appearing in 66 of the 68 patients (two had no response). In only one patient did the twitch change from ipsilateral to contralateral with advancing the catheter. In two patients, the twitch changed from ipsilateral to bilateral, suggesting anterior migration of the catheter. The initial twitch was noted when advancing the catheter by 1 cm in 53 of 68 patients, by 2 cm in a further 10 patients, and by 3 cm in two patients. In 12 of 66 patients, the responses disappeared with further advancement of the catheter and one became contralateral at 3 cm. In 38 patients, the twitch changed from one motor response to a more proximal one, suggesting a stimulation of a more rostral nerve root as the
Paramedian (n = 68)
Age (years)*
62 ± 11
Height (cm)* Weight (kg)*
170 ± 4 81 ± 21
BMI (kg/m2)*
28 ± 5
Epidural placement (number of patients) T12-L1
16
L1-L2
20
L2-L3
9
L3-L4
23
Angle of needle (°)
40 (17–67)
* Values are expressed as mean ± SD; values are expressed as mean, with range in parentheses.
123
Lateralizing Epidural Catheter Placement
Fig. 1 Angulation of the needle is measured using Adobe1 Photoshop1 (Adobe Systems, Inc, San Jose, CA, USA).
catheter advanced up the anterior gutter on the ipsilateral side. In all 68 patients, successful epidural anesthesia was obtained as evidenced by no response to surgical incision. The mean angle of epidural entry was 40° (range, 17°–67°) (Table 1).
Discussion The possibility that epidural catheters can be reliably lateralized is contrary to traditional teaching. Bromage [2] put it well when he stated: ‘‘It is not easy to predict the course a catheter will take once the epidural space has been penetrated.’’ This may be true when performing epidural anesthesia using the midline approach, but this study demonstrated that the lateralization of epidural catheters can be reliably achieved using the paramedian approach. Ipsilateral localization occurred in 66 of 68 patients. In no patient was a contralateral twitch noted. The angle of epidural entry was 40° (range, 17°–60°) to the midline. This is a significant medial angulation but one that consistently led to ipsilateral lateralization. A less acute angle may not provide such consistency. There are several limitations to this study. Firstly, the physical characteristics of epidural catheters vary. The stimulating catheter is fairly flexible. Whether the slightly more rigid nonstimulating catheter can be lateralized as reliably is unknown. Even though electrical stimulation verifies lateralization, spread of local anesthetics from multihole catheters may be less predictable. Secondly, the routine use of electrical stimulation to verify epidural entry has been debated [6] since it was first described in 1998 [11]. In two of our 68 patients, no twitch was elicited, yet successful epidural anesthetic was obtained. In the senior author’s (NES) hands, this technique offers no added
advantage over conventional signs (loss of resistance, etc). In addition, it is more expensive and entails more setup time. This study did not utilize the midline approach, the most commonly used approach in epidural anesthesia as the senior author has used the paramedian approach exclusively since 1977 to avoid equivocal signs of loss of resistance [9]. Finally, the dose of epidural analgesia may need to be changed if catheters can provide more targeted drug delivery. At one time, epidural analgesia had been considered the gold standard for postoperative analgesia, but its use has dwindled for a number of reasons, including a high rate of unreliability [8] and side effects [7, 10, 13]. Typically, epidural catheters are placed using the midline approach, wherein there is no control over catheter placement [2]. Catheters are likely to lie in the contralateral epidural space contributing to ineffective analgesia and side effects, including contralateral leg numbness and weakness [10, 13]. This study suggests that epidural analgesia could be improved by using the paramedian approach to selectively administer postoperative epidural analgesia, thereby reducing the likelihood of side effects and optimizing local anesthetic/pain control delivery. Our study suggests that the majority of the catheters remained ipsilateral as the catheter was advanced because the twitch remained the same or changed in motor response character the majority of the time. However, in 12 of 66 patients, the twitch disappeared with advancement of the catheter beyond 2 cm. Whether the catheter had passed more posteriorly is unknown. This suggests that catheters should be advanced no more than 2 to 4 cm to preserve ipsilateral placement. It is assumed in this study that a twitch meant that the catheter was in close proximity to a nerve root in the anterolateral epidural space. This was a feasibility study to determine whether lateralizing epidural catheter could be performed as evidenced by electrical stimulation. There was no evidence that lateralizing the epidural catheter improved surgical anesthesia, as the doses used were large (25–30 mL). However, it is possible that lateralizing the epidural catheter may enable lower doses of anesthetic to be administered for anesthesia. In conclusion, this study demonstrated that lateralization of epidural catheters is feasible using the paramedian approach, which should optimize the quality of epidural analgesia and reduce the likelihood of side effects.
References 1. Botwin KP, Natalicchio J, Hanna A. Fluoroscopic guided lumbar interlaminar epidural injections: a prospective evaluation of epidurography contrast patterns and anatomical review of the epidural space. Pain Physician. 2004;7:77–80.
123
Clinical Orthopaedics and Related Research1
Sharrock and Go 2. Bromage PR. Epidural Analgesia. Philadelphia, PA: WB Saunders; 1978:220. 3. Candido KD, Raghavendra MS, Chinthagada M, Badiee S, Trepashko DW. A prospective evaluation of iodinated contrast flow patterns with fluoroscopically guided lumbar epidural steroid injections: the lateral parasagittal interlaminar epidural approach versus the transforaminal epidural approach. Anesth Analg. 2008;106:638–644. 4. Candido KD, Rana MV, Sauer R, Chupatanakul L, Tharian A, Vasic V, Knezevic NN. Concordant pressure paresthesia during interlaminar lumbar epidural steroid injections correlates with pain relief in patients with unilateral radicular pain. Pain Physician. 2013;16:497–511. 5. Chan SY, De la Cuadra Fontaine JC, Doan J, Tran de QH. Stimulating cervical epidural catheter. Anesth Analg. 2006;102:1910. 6. Forster JG, Niemi TT, Salmenpera MT, Ikonen S, Rosenberg PH. An evaluation of the epidural catheter position by epidural nerve stimulation in conjunction with continuous epidural analgesia in adult surgical patients. Anesth Analg. 2009;108:351–358. 7. Liu SS, Bae JJ, Bieltz M, Wukovits B, Ma Y. A prospective survey of patient-controlled epidural analgesia with bupivacaine and clonidine after total hip replacement: a pre- and postchange
123
8. 9.
10.
11.
12.
13.
comparison with bupivacaine and hydromorphone in 1,000 patients. Anesth Analg. 2011;113:1213–1217. Rawal N. Epidural technique for postoperative pain: gold standard no more? Reg Anesth Pain Med. 2012;37:310–317. Sharrock NE. Recordings of, and an anatomical explanation for, false positive loss of resistance during lumbar extradural analgesia. Br J Anaesth. 1979;51:253–258. Singelyn FJ, Deyaert M, Joris D, Pendeville E, Gouverneur JM. Effects of intravenous patient-controlled analgesia with morphine, continuous epidural analgesia, and continuous three-in-one block on postoperative pain and knee rehabilitation after unilateral total knee arthroplasty. Anesth Analg. 1998;87:88–92. Tsui BC, Gupta S, Finucane B. Confirmation of epidural catheter placement using nerve stimulation. Can J Anaesth. 1998;45:640– 644. Tsui BC, Wagner A, Cave D, Seal R. Threshold current for an insulated epidural needle in pediatric patients. Anesth Analg. 2004;99:694–696. Zaric D, Boysen K, Christiansen C, Christiansen J, Stephensen S, Christensen B. A comparison of epidural analgesia with combined continuous femoral-sciatic nerve blocks after total knee replacement. Anesth Analg. 2006;102:1240–1246.
