Regional Anesthesia and Pain Medicine • Volume 40, Number 2, March-April 2015
Letters to the Editor
Adductor Canal Block—or Subsartorial Canal Block? Accepted for publication: November 26, 2014.
To the Editor: read with great interest the conflicting correspondence between Jaeger et al1 and Bendtsen et al2 regarding the anatomy of the adductor canal and femoral triangle. The femoral triangle is unequivocally defined by the boundaries of the inguinal ligament superiorly, medial border of sartorius laterally, and the medial border of adductor longus medially. Once the neurovascular complex is posterior of sartorius (subsartorial), it is by definition not in the femoral triangle. It is lateral and possibly distal, as stated by Jaeger et al.1 If any ambiguity does exist, it is how to define the subsartorial space inferior of the femoral triangle but superior to the vastoadductor membrane. Bendtsen et al2 describe this as “located outside the adductor canal.” The confusion lies in the fact that some anatomy texts define the roof of the adductor canal as the vastoadductor membrane, whereas others state that it is the subsartorial continuation from the apex of the femoral triangle. Tubbs et al3 investigated the anatomy of the adductor canal and specifically the vastoadductor membrane by dissecting 16 embalmed cadavers. The membrane was identified in all specimens. The mean length from the anterior superior iliac spine to the proximal border of the vastoadductor membrane was 28 cm. Its length ranged from 5.5 to 15 cm long. Tubbs et al chose to use the term “subsartorial canal” to describe the space in its
I
FIGURE 2. Dissection showing absence of dye in the femoral triangle (1, femoral nerve; 2, sartorius muscle; 3, branch to rectus femoris; 4, articular branches; 5, femoral vessels).
entirety and reserved the term “adductor canal” for the distal portion enclosed by the vastoadductor membrane. Perhaps a more accurate and globally accepted term for an “adductor canal block” would be a “subsartorial canal block.” The distinction is probably of little clinical importance as dye appears to pass freely from the “subsartorial canal” in to the “adductor canal” as reported by Ishiguro and colleagues4 in their cadaveric study. They reported that 10 mL of dye injected subsartorially at the apex of the femoral triangle in 9 cadavers spreads to the lower edge of the adductor canal. Our group repeated these dissections using 3 fresh cadaveric legs. A 100-mm 20-gauge Pajunk needle and catheter kit was used. Under ultrasound guidance, the catheter was inserted between the sartorius and the rectus femoris muscles after the bifurcation of the femoral artery and the departure of the lateral circumflex femoral artery. Twenty milliliters of 0.25% Aniline blue was injected through the catheters and the anterior thighs dissected. The distance between the catheter entry site and
the mid-inguinal ligament was measured for each specimen. It was 9, 11, and 13 cm, respectively. In all 3 specimens, dye was found to spread from the apex of the femoral triangle into the adductor canal. In 1 specimen, dye was found at the adductor hiatus (Fig. 1). We and Ishiguro et al4 also found limited spread of dye cephalad in to the femoral triangle with dye sparing of the femoral nerve branches to sartorius, rectus femoris, and vastus lateralis (Fig. 2). In summary, cadaveric anatomical dissections confirm that dye injected at the level of the apex of the femoral triangle in the subsartorial canal spreads distally in to the adductor canal but not proximally. This supports and explains the published clinical findings reporting that “subsartorial canal” blocks can provide analgesia for knee surgery with preservation of quadriceps strength.5,6
Phillip Cowlishaw, MBChB Pierre Kotze, MBChB Mater Hospitals Brisbane, Queensland, Australia
The authors declare no conflict of interest.
REFERENCES
FIGURE 1. Detailed dissection of the adductor canal revealing dye down to the adductor hiatus. © 2014 American Society of Regional Anesthesia and Pain Medicine
1. Jaeger P, Lund J, Jenstrup MT, Brondum V, Dahl JB. Reply to Dr Bendtsen. Reg Anesth Pain Med. 2014;39:254–255. 2. Bendtsen TF, Moriggl B, Chan V, Pedersen EM, Borglum J. Redefining the adductor canal block. Reg Anesth Pain Med. 2014;39:442–443. 3. Tubbs RS, Loukas M, Shoja MM, Apaydin N, Oakes WJ, Salter EG. Anatomy and potential clinical significance of the vastoadductor membrane. Surg Radiol Anat. 2007;29:569–573.
175
Copyright © 2015 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
Regional Anesthesia and Pain Medicine • Volume 40, Number 2, March-April 2015
Letters to the Editor 4. Ishiguro S, Yokochi A, Yoshioka K, et al. Technical communication: anatomy and clinical implications of ultrasound-guided selective femoral nerve block. Anesth Analg. 2012;115: 1467–1470. 5. Jaeger P, Zaric D, Fomsgaard JS, et al. Adductor canal block versus femoral nerve block for analgesia after total knee arthroplasty: a randomized, double-blind study. Reg Anesth Pain Med. 2013; 38:526–532. 6. Hanson NA, Allen CJ, Hostetter LS, et al. Continuous ultrasound-guided adductor canal block for total knee arthroplasty: a randomized, double-blind trial. Anesth Analg. 2014;118: 1370–1377.
Block Awake or Asleep Still a Conundrum? Accepted for publication: December 9, 2014. To the Editor: read with interest the report from the Pediatric Regional Anesthesia Network by Taenzer et al1 regarding pediatric regional block complications. Performance of regional blocks in the awake versus anesthetized or heavily sedated state is a controversial topic in regional anesthesia. This report supports the safety of regional blocks in anesthetized children, which all pediatric anesthesiologists will agree with and in fact is paramount for the safe performance of pediatric regional anesthesia. Concerns of neural damage in anesthetized adults cannot be warranted. Currently, there are no specific or sensitive indicators of nerve injury. Subjective symptoms of neural injury such as pain and paresthesia are unreliable even in awake patients.2 Evidence shows that intraneural injection occurs quite frequently even in experienced hands, not invariably resulting in nerve damage.3 Perception of high injection pressures, too, is unreliable and can be confounded by needle make and design.4 With the use of ultrasound, high injection pressures should prompt the clinician to refocus on needle tip position. I suggest that block performance in adults should be individualized to the particular patient with emphasis on the risk-benefit ratio. Heavy sedation/anesthesia should be offered to anxious patients as well as for procedures near critical structures to prevent unintentional movement. Trainee anesthesiologists, too, would benefit from block performance in such patients by the provision of precious time and a still target, thereby improving relative safety.
I
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I do not entirely agree with the comments in the related editorial by Dalens and Albert5 that “individual perception of sound decisions is no longer deemed appropriate.” The human-factors movement recognizes the importance of “gut feeling” borne out of years of experience in the medical field, suggesting that it is something that should be valued.6 Jayaprakash J. Patil, MD Department of Anesthesiology and Intensive Care Airedale General Hospital Steeton, United Kingdom
The author declares no conflict of interest. REFERENCES 1. Taenzer AH, Walker BJ, Bosenberg AT, et al. Asleep vs. awake—does it matter? Pediatric regional block complications by patient state. A report from the Pediatric Regional Anesthesia Network (PRAN). Reg Anesth Pain Med. 2014; 39:279–283. 2. Cohen JM, Gray AT. Functional deficits after intraneural injection during interscalene block. Reg Anesth Pain Med. 2010;35:397–399. 3. Bigeleisen PE. Nerve puncture and apparent intraneural injection during ultrasound-guided axillary block does not invariably result in neurologic injury. Anesthesiology. 2006;105: 779–783. 4. Patil JJ, Ford S, Egeler C, Williams DJ. The effect of needle dimensions and infusion rates on injection pressures in regional anaesthesia needles: a bench-top study. Anaesthesia. 2015;70:183–189. 5. Dalens B, Albert N. Asleep or awake: rethinking “safety.” Reg Anesth Pain Med. 2014;39:267–268. 6. Boyd G. Clinical judgement and the emotions. Intern Med J. 2014;44:704–706.
Wrong-Side Nerve Blocks Can Be Avoided Accepted for publication: December 9, 2014. To the Editor: n response to the letter by Lie and Letheren,1 I would like to draw readers’ attention to a care bundle developed at our hospital to reduce wrong-side nerve blocks. In recent years, many new safety initiatives have been introduced in the United Kingdom including the World Health Organization Surgical Safety checklist, the “Stop Before You Block” (SBYB) campaign, and a national incident reporting system.2,3 Despite this, wrong-side blocks continue to occur.
I
Although specifically excluded from the UK list of “never events,”4 a wrongside nerve block should be considered a significant incident, warranting a thorough investigation. They expose the patient to increased risk of adverse effects and complications. When combined with a correctside procedure, there is a higher risk of local anesthetic toxicity from the combined dosage. There is added risk of prolonged immobility, inadequate physiotherapy and mobilization, and longer inpatient stay. Such incidents also suggest system failure and the need to enhance existing safeguards. A number of case reports have described the root causes of such events.5,6 Following this incident, we have introduced a bundle of measures: • Minimize position change during the anaesthetic process. • Perform block prior to a spinal anaesthetic where possible. • Place stimulator electrode on the surgical marking arrow as a further visual confirmation to the side of block. This should happen routinely whether nerve stimulator is to be used or not. • Introduce a “block box.” This consists of an “up-cycled”’ HNS11/12 nerve stimulator plastic box, from which the foam inserts have been removed to allow sterilization. The cover of the block box has an SBYB A4 laminate on it. Any equipment related to the performance of a regional anesthetic is placed in this box before the patient’s arrival. This has the added advantage of ensuring that syringes of clear local anesthetic solution are not in the same location as syringes meant for intravenous administration. At performance of the block, the SBYB check is completed before the box is opened, and the block performed. • Adapt and increase presence of the SBYB campaign poster. Laminated A6 size copies have been attached to the nerve stimulators. Laminated A4 copies have also been attached to front of our ultrasound machines, and the front of the block boxes.
We believe that this bundle adds further barriers to recurrence of wrong-sided blocks, “blinding” the holes in the Swisscheese model. We welcome further discussion.
Priti Kamath, MBBS, BSc, FRCA James Stimpson, FRCA, MRCP Alistair Steel, FRCA, MRCP Anaesthesia Department The Queen Elizabeth Hospital King’s Lynn NHS Foundation Trust Norfolk, United Kingdom
© 2014 American Society of Regional Anesthesia and Pain Medicine
Copyright © 2015 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
Letters to the Editor
Adductor Canal Block—or Subsartorial Canal Block? Accepted for publication: November 26, 2014.
To the Editor: read with great interest the conflicting correspondence between Jaeger et al1 and Bendtsen et al2 regarding the anatomy of the adductor canal and femoral triangle. The femoral triangle is unequivocally defined by the boundaries of the inguinal ligament superiorly, medial border of sartorius laterally, and the medial border of adductor longus medially. Once the neurovascular complex is posterior of sartorius (subsartorial), it is by definition not in the femoral triangle. It is lateral and possibly distal, as stated by Jaeger et al.1 If any ambiguity does exist, it is how to define the subsartorial space inferior of the femoral triangle but superior to the vastoadductor membrane. Bendtsen et al2 describe this as “located outside the adductor canal.” The confusion lies in the fact that some anatomy texts define the roof of the adductor canal as the vastoadductor membrane, whereas others state that it is the subsartorial continuation from the apex of the femoral triangle. Tubbs et al3 investigated the anatomy of the adductor canal and specifically the vastoadductor membrane by dissecting 16 embalmed cadavers. The membrane was identified in all specimens. The mean length from the anterior superior iliac spine to the proximal border of the vastoadductor membrane was 28 cm. Its length ranged from 5.5 to 15 cm long. Tubbs et al chose to use the term “subsartorial canal” to describe the space in its
I
FIGURE 2. Dissection showing absence of dye in the femoral triangle (1, femoral nerve; 2, sartorius muscle; 3, branch to rectus femoris; 4, articular branches; 5, femoral vessels).
entirety and reserved the term “adductor canal” for the distal portion enclosed by the vastoadductor membrane. Perhaps a more accurate and globally accepted term for an “adductor canal block” would be a “subsartorial canal block.” The distinction is probably of little clinical importance as dye appears to pass freely from the “subsartorial canal” in to the “adductor canal” as reported by Ishiguro and colleagues4 in their cadaveric study. They reported that 10 mL of dye injected subsartorially at the apex of the femoral triangle in 9 cadavers spreads to the lower edge of the adductor canal. Our group repeated these dissections using 3 fresh cadaveric legs. A 100-mm 20-gauge Pajunk needle and catheter kit was used. Under ultrasound guidance, the catheter was inserted between the sartorius and the rectus femoris muscles after the bifurcation of the femoral artery and the departure of the lateral circumflex femoral artery. Twenty milliliters of 0.25% Aniline blue was injected through the catheters and the anterior thighs dissected. The distance between the catheter entry site and
the mid-inguinal ligament was measured for each specimen. It was 9, 11, and 13 cm, respectively. In all 3 specimens, dye was found to spread from the apex of the femoral triangle into the adductor canal. In 1 specimen, dye was found at the adductor hiatus (Fig. 1). We and Ishiguro et al4 also found limited spread of dye cephalad in to the femoral triangle with dye sparing of the femoral nerve branches to sartorius, rectus femoris, and vastus lateralis (Fig. 2). In summary, cadaveric anatomical dissections confirm that dye injected at the level of the apex of the femoral triangle in the subsartorial canal spreads distally in to the adductor canal but not proximally. This supports and explains the published clinical findings reporting that “subsartorial canal” blocks can provide analgesia for knee surgery with preservation of quadriceps strength.5,6
Phillip Cowlishaw, MBChB Pierre Kotze, MBChB Mater Hospitals Brisbane, Queensland, Australia
The authors declare no conflict of interest.
REFERENCES
FIGURE 1. Detailed dissection of the adductor canal revealing dye down to the adductor hiatus. © 2014 American Society of Regional Anesthesia and Pain Medicine
1. Jaeger P, Lund J, Jenstrup MT, Brondum V, Dahl JB. Reply to Dr Bendtsen. Reg Anesth Pain Med. 2014;39:254–255. 2. Bendtsen TF, Moriggl B, Chan V, Pedersen EM, Borglum J. Redefining the adductor canal block. Reg Anesth Pain Med. 2014;39:442–443. 3. Tubbs RS, Loukas M, Shoja MM, Apaydin N, Oakes WJ, Salter EG. Anatomy and potential clinical significance of the vastoadductor membrane. Surg Radiol Anat. 2007;29:569–573.
175
Copyright © 2015 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
Regional Anesthesia and Pain Medicine • Volume 40, Number 2, March-April 2015
Letters to the Editor 4. Ishiguro S, Yokochi A, Yoshioka K, et al. Technical communication: anatomy and clinical implications of ultrasound-guided selective femoral nerve block. Anesth Analg. 2012;115: 1467–1470. 5. Jaeger P, Zaric D, Fomsgaard JS, et al. Adductor canal block versus femoral nerve block for analgesia after total knee arthroplasty: a randomized, double-blind study. Reg Anesth Pain Med. 2013; 38:526–532. 6. Hanson NA, Allen CJ, Hostetter LS, et al. Continuous ultrasound-guided adductor canal block for total knee arthroplasty: a randomized, double-blind trial. Anesth Analg. 2014;118: 1370–1377.
Block Awake or Asleep Still a Conundrum? Accepted for publication: December 9, 2014. To the Editor: read with interest the report from the Pediatric Regional Anesthesia Network by Taenzer et al1 regarding pediatric regional block complications. Performance of regional blocks in the awake versus anesthetized or heavily sedated state is a controversial topic in regional anesthesia. This report supports the safety of regional blocks in anesthetized children, which all pediatric anesthesiologists will agree with and in fact is paramount for the safe performance of pediatric regional anesthesia. Concerns of neural damage in anesthetized adults cannot be warranted. Currently, there are no specific or sensitive indicators of nerve injury. Subjective symptoms of neural injury such as pain and paresthesia are unreliable even in awake patients.2 Evidence shows that intraneural injection occurs quite frequently even in experienced hands, not invariably resulting in nerve damage.3 Perception of high injection pressures, too, is unreliable and can be confounded by needle make and design.4 With the use of ultrasound, high injection pressures should prompt the clinician to refocus on needle tip position. I suggest that block performance in adults should be individualized to the particular patient with emphasis on the risk-benefit ratio. Heavy sedation/anesthesia should be offered to anxious patients as well as for procedures near critical structures to prevent unintentional movement. Trainee anesthesiologists, too, would benefit from block performance in such patients by the provision of precious time and a still target, thereby improving relative safety.
I
176
I do not entirely agree with the comments in the related editorial by Dalens and Albert5 that “individual perception of sound decisions is no longer deemed appropriate.” The human-factors movement recognizes the importance of “gut feeling” borne out of years of experience in the medical field, suggesting that it is something that should be valued.6 Jayaprakash J. Patil, MD Department of Anesthesiology and Intensive Care Airedale General Hospital Steeton, United Kingdom
The author declares no conflict of interest. REFERENCES 1. Taenzer AH, Walker BJ, Bosenberg AT, et al. Asleep vs. awake—does it matter? Pediatric regional block complications by patient state. A report from the Pediatric Regional Anesthesia Network (PRAN). Reg Anesth Pain Med. 2014; 39:279–283. 2. Cohen JM, Gray AT. Functional deficits after intraneural injection during interscalene block. Reg Anesth Pain Med. 2010;35:397–399. 3. Bigeleisen PE. Nerve puncture and apparent intraneural injection during ultrasound-guided axillary block does not invariably result in neurologic injury. Anesthesiology. 2006;105: 779–783. 4. Patil JJ, Ford S, Egeler C, Williams DJ. The effect of needle dimensions and infusion rates on injection pressures in regional anaesthesia needles: a bench-top study. Anaesthesia. 2015;70:183–189. 5. Dalens B, Albert N. Asleep or awake: rethinking “safety.” Reg Anesth Pain Med. 2014;39:267–268. 6. Boyd G. Clinical judgement and the emotions. Intern Med J. 2014;44:704–706.
Wrong-Side Nerve Blocks Can Be Avoided Accepted for publication: December 9, 2014. To the Editor: n response to the letter by Lie and Letheren,1 I would like to draw readers’ attention to a care bundle developed at our hospital to reduce wrong-side nerve blocks. In recent years, many new safety initiatives have been introduced in the United Kingdom including the World Health Organization Surgical Safety checklist, the “Stop Before You Block” (SBYB) campaign, and a national incident reporting system.2,3 Despite this, wrong-side blocks continue to occur.
I
Although specifically excluded from the UK list of “never events,”4 a wrongside nerve block should be considered a significant incident, warranting a thorough investigation. They expose the patient to increased risk of adverse effects and complications. When combined with a correctside procedure, there is a higher risk of local anesthetic toxicity from the combined dosage. There is added risk of prolonged immobility, inadequate physiotherapy and mobilization, and longer inpatient stay. Such incidents also suggest system failure and the need to enhance existing safeguards. A number of case reports have described the root causes of such events.5,6 Following this incident, we have introduced a bundle of measures: • Minimize position change during the anaesthetic process. • Perform block prior to a spinal anaesthetic where possible. • Place stimulator electrode on the surgical marking arrow as a further visual confirmation to the side of block. This should happen routinely whether nerve stimulator is to be used or not. • Introduce a “block box.” This consists of an “up-cycled”’ HNS11/12 nerve stimulator plastic box, from which the foam inserts have been removed to allow sterilization. The cover of the block box has an SBYB A4 laminate on it. Any equipment related to the performance of a regional anesthetic is placed in this box before the patient’s arrival. This has the added advantage of ensuring that syringes of clear local anesthetic solution are not in the same location as syringes meant for intravenous administration. At performance of the block, the SBYB check is completed before the box is opened, and the block performed. • Adapt and increase presence of the SBYB campaign poster. Laminated A6 size copies have been attached to the nerve stimulators. Laminated A4 copies have also been attached to front of our ultrasound machines, and the front of the block boxes.
We believe that this bundle adds further barriers to recurrence of wrong-sided blocks, “blinding” the holes in the Swisscheese model. We welcome further discussion.
Priti Kamath, MBBS, BSc, FRCA James Stimpson, FRCA, MRCP Alistair Steel, FRCA, MRCP Anaesthesia Department The Queen Elizabeth Hospital King’s Lynn NHS Foundation Trust Norfolk, United Kingdom
© 2014 American Society of Regional Anesthesia and Pain Medicine
Copyright © 2015 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
