Letters to the Editor
this may be underestimated because of the nature of retrospective study. Selective tibial nerve block may be a good way to balance the peroneal motor function and postoperative analgesia.5 Keita Sato, MD Department of Anesthesiology Tokyo Women’s Medical University Tokyo, Japan
Takehiko Adachi, MD, PhD Department of Anesthesiology Kitano Hospital Osaka, Japan
The authors declare no conflict of interest. REFERENCES 1. Sato K, Adachi T, Shirai N, et al. Continuous versus single-injection sciatic nerve block added to continuous femoral nerve block for analgesia after total knee arthroplasty: a prospective, randomized, double-blind study. Reg Anesth Pain Med. 2014;39:225–229. 2. Krackow KA, Maar DC, Mont MA, et al. Surgical decompression for peroneal nerve palsy after total knee arthroplasty. Clin Orthop Relat Res. 1993;292:223–228. 3. Nercessian OA, Ugwonali OF, Park S. Peroneal nerve palsy after total knee arthroplasty. J Arthroplasty. 2005;20:1068–1073. 4. Zywiel MG, Mont MA, McGrath MS, et al. Peroneal nerve dysfunction after total knee arthroplasty: characterization and treatment. J Arthroplasty. 2011;26:379–385.
Regional Anesthesia and Pain Medicine • Volume 39, Number 6, November-December 2014
to present for surgical procedures. The patient and her family consented to the presentation of this case. A 22-year-old, 5-ft-2-in, 59-kg woman with PA was scheduled for an outpatient calcaneal osteotomy, lateral column lengthening, and tendon transfer of the left foot. Her medical history was also significant for dilated cardiomyopathy with an ejection fraction of 45%. Before surgery, ultrasoundguided popliteal and adductor canal saphenous blocks were performed using an inplane technique with a 100-mm Stimuplex needle (B. Braun Medical, Melsungen, Germany). A SonoSite S-Nerve ultrasound system (Bothell, Washington) was used for the block procedure, and 30 and 10 mL of 0.5% ropivacaine were injected around the sciatic and saphenous nerves, respectively. The patient underwent an uneventful surgery with dexmedetomidine sedation. No narcotics or additional analgesics were given in the operating room or the postanesthesia care unit. She was pain-free in the postanesthesia care unit and at home until block resolution the following morning. The patient was contacted 1 week later, and she denied any symptoms of nerve injury. Mitochondrial diseases are a heterogeneous group of disorders that result in patients having abnormal cellular energy metabolism. Propionic acidemia is a rare, life-threatening, autosomal recessive, mitochondrial disease affecting fewer than 1 in 100,000 live births.1 A genetic mutation results in a deficiency of propionyl-CoA carboxylase, an enzyme responsible for
catalyzing propionyl-CoA to methylmalonylCoA inside the mitochondria (Fig. 1) before entering the Krebs cycle, which is essential for ATP formation. The decision to perform peripheral nerve blocks on a patient with a known mitochondrial disorder is controversial because of the theoretical concern for an increased risk of local anesthetic systemic toxicity. Local anesthetics are known inhibitors of mitochondrial ATP production,2,3 and depending on the type and severity of the disorder, this inhibition may be deleterious in patients with preexisting mitochondrial dysfunction. Despite this, it has been reported that local anesthetics have been used safely (presumably via infiltration) in patients with mitochondrial disorders.2 Our patient reported that her wisdom teeth were uneventfully extracted under local anesthesia, and this was at least partly reassuring with respect to her ability to tolerate local anesthetics. Anesthesiologists should be cautious with local anesthetic doses to minimize the risk of local anesthetic systemic toxicity, particularly because the effects of intralipid rescue in this patient population are unknown. Because metabolism of fatty acids is known to contribute to the reversal of bupivacaine cardiac toxicity by lipid emulsion infusion, it is possible that lipid emulsion’s benefits are reduced when fatty acids are metabolized less efficiently.4 Our limited but favorable experience in a patient with PA suggests that regional anesthesia may be safe in select patients with mitochondrial disorders.
5. Sinha SK, Abrams JH, Arumugam S, et al. Femoral nerve block with selective tibial nerve block provides effective analgesia without foot drop after total knee arthroplasty: a prospective, randomized, observer-blinded study. Anesth Analg. 2012;115:202–206.
Peripheral Nerve Block in a Patient With Propionic Acidemia Accepted for publication: July 30, 2014. To the Editor: e would like to relate our experience with the use of peripheral nerve blocks in a patient with propionic acidemia (PA). We believe that this is the first reported use of ultrasound-guided peripheral nerve blocks as a primary anesthetic in a patient with a mitochondrial disorder. As increasing numbers of patients with this and other uncommon metabolic disorders are living to adulthood, they are more likely
W
560
FIGURE 1. Metabolic pathway. Propionyl-CoA carboxylase (PCC) catalyzes the conversion of propionyl-CoA to methylmalonyl-CoA, which enters the Krebs cycle via succinyl-CoA. Sources of propionate include valine, isoleucine, threonine, methionine, odd-chain fatty acids, and cholesterol. Deficiency of PCC results in PA and accumulation of 3-OH propionate, methylcitrate, and glycine, among other metabolites. PCC is located inside the mitochondrion. PCC, a heterododecamer (α6β6), comprises 6 α-subunits (orange) and 6 β-subunits (purple). Biotin (blue), bicarbonate, and ATP have binding sites in the α-subunit. The β-subunits form a central core. Reprinted with permission from Carrillo-Carrasco N, Venditti C. Propionic Acidemia. In: Pagon RA, Adam MP, Bird TD, Dolan CR, Fong CT, Stephens K, eds. GeneReviews™ [Internet]. Seattle (WA): University of Washington, Seattle; 1993–2013. 2012 May 17. http://www.ncbi.nlm.nih.gov/books/NBK92946/. © 2014 American Society of Regional Anesthesia and Pain Medicine
Copyright © 2014 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
Regional Anesthesia and Pain Medicine • Volume 39, Number 6, November-December 2014
José Raul Soberón, MD Clint E. Elliott, MD Kim S. Bland, MD Department of Anesthesiology Ochsner Clinic Foundation New Orleans, LA
Guy L. Weinberg, MD Department of Anesthesiology University of Illinois College of Medicine at Chicago Chicago, IL
The authors declare no conflict of interest. REFERENCES 1. Kleinman RE, Walker WA. Walker's Pediatric Gastrointestinal Disease: Physiology, Diagnosis, Management. Hamilton, Ontario, Canada: BC Decker, 2008. 2. Ellinas H, Frost EA. Mitochondrial disorders—a review of anesthetic considerations. Middle East J Anesthesiol. 2011;21:235–242. 3. Nouette-Gaulain K, Capdevila X, Rossignol R. Local anesthetic ‘in-situ’ toxicity during peripheral nerve blocks: update on mechanisms and prevention. Curr Opin Anaesthesiol. 2012;25:589–595. 4. Partownavid P, Umar S, Li J, Rahman S, Eghbali M. Fatty-acid oxidation and calcium homeostasis are involved in the rescue of bupivacaine-induced cardiotoxicity by lipid emulsion in rats. Crit Care Med. 2012;40: 2431–437.
A Modification of the Single-Penetration, Dual-Injection Technique for Combined Sciatic and Saphenous Nerve Blocks To the Editor: e read with great interest the recent article by Børglum et al1 promoting an ultrasound-guided, single-penetration, dual-injection (SPEDI) technique for combined sciatic and saphenous nerve blocks. Their evidence suggests this technique is equally effective and faster than saphenous and sciatic blocks performed independently. The SPEDI technique is performed in the proximal thigh at the level of the lesser trochanter under ultrasound visualization of both sciatic and femoral nerves. Practitioners experienced with ultrasoundguided blocks of the lower extremity will note that ultrasound identification of the sciatic nerve anteriorly in the proximal thigh is technically challenging. This is especially true in obese patients, and it is interesting to note that the average adult male body mass index in the United
W
States is more than 4 points higher than in Denmark (where the SPEDI study was conducted).2 We agree when Dr Børglum and colleagues state the traditional “poplitealsciatic approach necessitates an elevation of the leg exposing the popliteal fossa or placement of the patient in the lateral or prone position,” which adds significant time to the procedure and may result in pain for the patient. However, we have used a modification of the described SPEDI technique that allows for improved ultrasound visualization of the sciatic nerve and avoids elevating the lower leg. This technique is also a “single-penetration, dual-injection” sciaticsaphenous block, but it is performed in the distal thigh via a medial approach. The patient’s knee is slightly bent and externally rotated, or “frog-legged,” allowing the ultrasound to be applied posteriorly to the popliteal fossa. The 2 branches of the sciatic nerve are identified at the level of the popliteal crease and traced proximally 4 to 8 cm until they join. At that point, a skin wheal is placed on the medial thigh allowing for in-plane needle visualization. After injectate is delivered around the sciatic nerve, the probe is then moved anteromedially, allowing visualization of the femoral artery. Using the same entry point, the needle is partially withdrawn and redirected anteriorly for saphenous nerve blockade.3 This approach offers the same advantages of efficiency while allowing for easy ultrasound-guided sciatic and saphenous nerve blocks. It also allows for avoidance of leg elevation required for the traditional lateral popliteal nerve block. We have used this modified technique on several patients successfully, but we acknowledge overall efficacy has yet to be proven. Stephen Harvey, MD John Corey, MD Kress Townley, MD Department of Anesthesiology Vanderbilt University Medical Center Nashville, TN [email protected]
The authors declares no conflict of interest. REFERENCES 1. Børglum J, Johansen K, Christensen MD, et al. Ultrasound-guided single-penetration dual-injection block for leg and foot surgery. Reg Anesth Pain Med. 2014;39:18–25. 2. WHO Global Infobase. Projected 2015 BMI values from WHO Info Database. Available at: apps.who.int/infobase/Indicators.aspx. Accessed July 3, 2014. 3. Krombach J, Gray AT. Sonography for saphenous nerve block near the adductor canal. Reg Anesth Pain Med. 2007;32:369–370.
© 2014 American Society of Regional Anesthesia and Pain Medicine
Letters to the Editor
Alcohol Swabs as “Cold Test” in a Measure of Temperature Sensation in the Skin Accepted for publication: August 18, 2014. To the Editor: e read with interest a recent article by Choquet et al,1 which described alternate approaches to ensuring adequate local anesthetic spread for ultrasound-guided popliteal sciatic nerve block. One of the methods used by the authors to assess sensory block was a loss of cold sensation in the tibial and common peroneal nerve distributions; however, the method of testing cold sensation was not given. Because afferent nerve fibers that conduct impulses for pain and temperature belong to the same group of Aδ fibers,2 loss of sensation to cold is commonly used in regional anesthesia as a surrogate for loss of pain sensation. The “cold test” can be performed with ice,3 a cold gel bag,4 and alcohol.5 Compared with other block assessment methods (eg, pinprick), it has minimal risk of trauma to the skin. Nevertheless, none of the coldtest methods has been shown to be superior to the others, and cold testing remains unstandardized and largely influenced by personal preference.6 We therefore conducted a study comparing the evaporative cooling effect of an alcohol swab with a swab that felt similar to the touch but was actually cold. After approval by the institutional Health Research Ethics Board and written consent, 40 healthy staff volunteers were recruited. The volunteers were swabbed with a regular alcohol swab (70% isopropyl alcohol; Canada Supply Inc, Mississauga, Ontario, Canada) at room temperature and a frozen swab. To prepare the frozen swabs, alcohol swabs were dried, wet with 4 drops of water, and frozen at −70°C for at least 12 hours. The swabs were applied simultaneously and randomly to one of the volunteers’ forearms on a hairless area. Volunteers were blinded to the properties of the swabs and were asked to determine if each swab felt “cold” or “not cold.” Most volunteers perceived the alcohol swab (n = 36/40) and frozen swab (n = 37/40) as cold (Fig. 1). A Fisher exact test demonstrated no statistically significant difference in perceived cold sensation between the 2 swabs (P = 1.00). Our results suggest that room-temperature alcohol swabs are a reasonable equivalent form of testing cold sensation. A limitation of this study was that the temperature generated from the evaporative effect of the alcohol was not measured because the cooling effect above the skin would be difficult to quantify. Also, the temperature of the frozen swabs (−9.5°C) was colder than ice (∼0°C), the typical cold stimulus used in
W
561
Copyright © 2014 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
this may be underestimated because of the nature of retrospective study. Selective tibial nerve block may be a good way to balance the peroneal motor function and postoperative analgesia.5 Keita Sato, MD Department of Anesthesiology Tokyo Women’s Medical University Tokyo, Japan
Takehiko Adachi, MD, PhD Department of Anesthesiology Kitano Hospital Osaka, Japan
The authors declare no conflict of interest. REFERENCES 1. Sato K, Adachi T, Shirai N, et al. Continuous versus single-injection sciatic nerve block added to continuous femoral nerve block for analgesia after total knee arthroplasty: a prospective, randomized, double-blind study. Reg Anesth Pain Med. 2014;39:225–229. 2. Krackow KA, Maar DC, Mont MA, et al. Surgical decompression for peroneal nerve palsy after total knee arthroplasty. Clin Orthop Relat Res. 1993;292:223–228. 3. Nercessian OA, Ugwonali OF, Park S. Peroneal nerve palsy after total knee arthroplasty. J Arthroplasty. 2005;20:1068–1073. 4. Zywiel MG, Mont MA, McGrath MS, et al. Peroneal nerve dysfunction after total knee arthroplasty: characterization and treatment. J Arthroplasty. 2011;26:379–385.
Regional Anesthesia and Pain Medicine • Volume 39, Number 6, November-December 2014
to present for surgical procedures. The patient and her family consented to the presentation of this case. A 22-year-old, 5-ft-2-in, 59-kg woman with PA was scheduled for an outpatient calcaneal osteotomy, lateral column lengthening, and tendon transfer of the left foot. Her medical history was also significant for dilated cardiomyopathy with an ejection fraction of 45%. Before surgery, ultrasoundguided popliteal and adductor canal saphenous blocks were performed using an inplane technique with a 100-mm Stimuplex needle (B. Braun Medical, Melsungen, Germany). A SonoSite S-Nerve ultrasound system (Bothell, Washington) was used for the block procedure, and 30 and 10 mL of 0.5% ropivacaine were injected around the sciatic and saphenous nerves, respectively. The patient underwent an uneventful surgery with dexmedetomidine sedation. No narcotics or additional analgesics were given in the operating room or the postanesthesia care unit. She was pain-free in the postanesthesia care unit and at home until block resolution the following morning. The patient was contacted 1 week later, and she denied any symptoms of nerve injury. Mitochondrial diseases are a heterogeneous group of disorders that result in patients having abnormal cellular energy metabolism. Propionic acidemia is a rare, life-threatening, autosomal recessive, mitochondrial disease affecting fewer than 1 in 100,000 live births.1 A genetic mutation results in a deficiency of propionyl-CoA carboxylase, an enzyme responsible for
catalyzing propionyl-CoA to methylmalonylCoA inside the mitochondria (Fig. 1) before entering the Krebs cycle, which is essential for ATP formation. The decision to perform peripheral nerve blocks on a patient with a known mitochondrial disorder is controversial because of the theoretical concern for an increased risk of local anesthetic systemic toxicity. Local anesthetics are known inhibitors of mitochondrial ATP production,2,3 and depending on the type and severity of the disorder, this inhibition may be deleterious in patients with preexisting mitochondrial dysfunction. Despite this, it has been reported that local anesthetics have been used safely (presumably via infiltration) in patients with mitochondrial disorders.2 Our patient reported that her wisdom teeth were uneventfully extracted under local anesthesia, and this was at least partly reassuring with respect to her ability to tolerate local anesthetics. Anesthesiologists should be cautious with local anesthetic doses to minimize the risk of local anesthetic systemic toxicity, particularly because the effects of intralipid rescue in this patient population are unknown. Because metabolism of fatty acids is known to contribute to the reversal of bupivacaine cardiac toxicity by lipid emulsion infusion, it is possible that lipid emulsion’s benefits are reduced when fatty acids are metabolized less efficiently.4 Our limited but favorable experience in a patient with PA suggests that regional anesthesia may be safe in select patients with mitochondrial disorders.
5. Sinha SK, Abrams JH, Arumugam S, et al. Femoral nerve block with selective tibial nerve block provides effective analgesia without foot drop after total knee arthroplasty: a prospective, randomized, observer-blinded study. Anesth Analg. 2012;115:202–206.
Peripheral Nerve Block in a Patient With Propionic Acidemia Accepted for publication: July 30, 2014. To the Editor: e would like to relate our experience with the use of peripheral nerve blocks in a patient with propionic acidemia (PA). We believe that this is the first reported use of ultrasound-guided peripheral nerve blocks as a primary anesthetic in a patient with a mitochondrial disorder. As increasing numbers of patients with this and other uncommon metabolic disorders are living to adulthood, they are more likely
W
560
FIGURE 1. Metabolic pathway. Propionyl-CoA carboxylase (PCC) catalyzes the conversion of propionyl-CoA to methylmalonyl-CoA, which enters the Krebs cycle via succinyl-CoA. Sources of propionate include valine, isoleucine, threonine, methionine, odd-chain fatty acids, and cholesterol. Deficiency of PCC results in PA and accumulation of 3-OH propionate, methylcitrate, and glycine, among other metabolites. PCC is located inside the mitochondrion. PCC, a heterododecamer (α6β6), comprises 6 α-subunits (orange) and 6 β-subunits (purple). Biotin (blue), bicarbonate, and ATP have binding sites in the α-subunit. The β-subunits form a central core. Reprinted with permission from Carrillo-Carrasco N, Venditti C. Propionic Acidemia. In: Pagon RA, Adam MP, Bird TD, Dolan CR, Fong CT, Stephens K, eds. GeneReviews™ [Internet]. Seattle (WA): University of Washington, Seattle; 1993–2013. 2012 May 17. http://www.ncbi.nlm.nih.gov/books/NBK92946/. © 2014 American Society of Regional Anesthesia and Pain Medicine
Copyright © 2014 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
Regional Anesthesia and Pain Medicine • Volume 39, Number 6, November-December 2014
José Raul Soberón, MD Clint E. Elliott, MD Kim S. Bland, MD Department of Anesthesiology Ochsner Clinic Foundation New Orleans, LA
Guy L. Weinberg, MD Department of Anesthesiology University of Illinois College of Medicine at Chicago Chicago, IL
The authors declare no conflict of interest. REFERENCES 1. Kleinman RE, Walker WA. Walker's Pediatric Gastrointestinal Disease: Physiology, Diagnosis, Management. Hamilton, Ontario, Canada: BC Decker, 2008. 2. Ellinas H, Frost EA. Mitochondrial disorders—a review of anesthetic considerations. Middle East J Anesthesiol. 2011;21:235–242. 3. Nouette-Gaulain K, Capdevila X, Rossignol R. Local anesthetic ‘in-situ’ toxicity during peripheral nerve blocks: update on mechanisms and prevention. Curr Opin Anaesthesiol. 2012;25:589–595. 4. Partownavid P, Umar S, Li J, Rahman S, Eghbali M. Fatty-acid oxidation and calcium homeostasis are involved in the rescue of bupivacaine-induced cardiotoxicity by lipid emulsion in rats. Crit Care Med. 2012;40: 2431–437.
A Modification of the Single-Penetration, Dual-Injection Technique for Combined Sciatic and Saphenous Nerve Blocks To the Editor: e read with great interest the recent article by Børglum et al1 promoting an ultrasound-guided, single-penetration, dual-injection (SPEDI) technique for combined sciatic and saphenous nerve blocks. Their evidence suggests this technique is equally effective and faster than saphenous and sciatic blocks performed independently. The SPEDI technique is performed in the proximal thigh at the level of the lesser trochanter under ultrasound visualization of both sciatic and femoral nerves. Practitioners experienced with ultrasoundguided blocks of the lower extremity will note that ultrasound identification of the sciatic nerve anteriorly in the proximal thigh is technically challenging. This is especially true in obese patients, and it is interesting to note that the average adult male body mass index in the United
W
States is more than 4 points higher than in Denmark (where the SPEDI study was conducted).2 We agree when Dr Børglum and colleagues state the traditional “poplitealsciatic approach necessitates an elevation of the leg exposing the popliteal fossa or placement of the patient in the lateral or prone position,” which adds significant time to the procedure and may result in pain for the patient. However, we have used a modification of the described SPEDI technique that allows for improved ultrasound visualization of the sciatic nerve and avoids elevating the lower leg. This technique is also a “single-penetration, dual-injection” sciaticsaphenous block, but it is performed in the distal thigh via a medial approach. The patient’s knee is slightly bent and externally rotated, or “frog-legged,” allowing the ultrasound to be applied posteriorly to the popliteal fossa. The 2 branches of the sciatic nerve are identified at the level of the popliteal crease and traced proximally 4 to 8 cm until they join. At that point, a skin wheal is placed on the medial thigh allowing for in-plane needle visualization. After injectate is delivered around the sciatic nerve, the probe is then moved anteromedially, allowing visualization of the femoral artery. Using the same entry point, the needle is partially withdrawn and redirected anteriorly for saphenous nerve blockade.3 This approach offers the same advantages of efficiency while allowing for easy ultrasound-guided sciatic and saphenous nerve blocks. It also allows for avoidance of leg elevation required for the traditional lateral popliteal nerve block. We have used this modified technique on several patients successfully, but we acknowledge overall efficacy has yet to be proven. Stephen Harvey, MD John Corey, MD Kress Townley, MD Department of Anesthesiology Vanderbilt University Medical Center Nashville, TN [email protected]
The authors declares no conflict of interest. REFERENCES 1. Børglum J, Johansen K, Christensen MD, et al. Ultrasound-guided single-penetration dual-injection block for leg and foot surgery. Reg Anesth Pain Med. 2014;39:18–25. 2. WHO Global Infobase. Projected 2015 BMI values from WHO Info Database. Available at: apps.who.int/infobase/Indicators.aspx. Accessed July 3, 2014. 3. Krombach J, Gray AT. Sonography for saphenous nerve block near the adductor canal. Reg Anesth Pain Med. 2007;32:369–370.
© 2014 American Society of Regional Anesthesia and Pain Medicine
Letters to the Editor
Alcohol Swabs as “Cold Test” in a Measure of Temperature Sensation in the Skin Accepted for publication: August 18, 2014. To the Editor: e read with interest a recent article by Choquet et al,1 which described alternate approaches to ensuring adequate local anesthetic spread for ultrasound-guided popliteal sciatic nerve block. One of the methods used by the authors to assess sensory block was a loss of cold sensation in the tibial and common peroneal nerve distributions; however, the method of testing cold sensation was not given. Because afferent nerve fibers that conduct impulses for pain and temperature belong to the same group of Aδ fibers,2 loss of sensation to cold is commonly used in regional anesthesia as a surrogate for loss of pain sensation. The “cold test” can be performed with ice,3 a cold gel bag,4 and alcohol.5 Compared with other block assessment methods (eg, pinprick), it has minimal risk of trauma to the skin. Nevertheless, none of the coldtest methods has been shown to be superior to the others, and cold testing remains unstandardized and largely influenced by personal preference.6 We therefore conducted a study comparing the evaporative cooling effect of an alcohol swab with a swab that felt similar to the touch but was actually cold. After approval by the institutional Health Research Ethics Board and written consent, 40 healthy staff volunteers were recruited. The volunteers were swabbed with a regular alcohol swab (70% isopropyl alcohol; Canada Supply Inc, Mississauga, Ontario, Canada) at room temperature and a frozen swab. To prepare the frozen swabs, alcohol swabs were dried, wet with 4 drops of water, and frozen at −70°C for at least 12 hours. The swabs were applied simultaneously and randomly to one of the volunteers’ forearms on a hairless area. Volunteers were blinded to the properties of the swabs and were asked to determine if each swab felt “cold” or “not cold.” Most volunteers perceived the alcohol swab (n = 36/40) and frozen swab (n = 37/40) as cold (Fig. 1). A Fisher exact test demonstrated no statistically significant difference in perceived cold sensation between the 2 swabs (P = 1.00). Our results suggest that room-temperature alcohol swabs are a reasonable equivalent form of testing cold sensation. A limitation of this study was that the temperature generated from the evaporative effect of the alcohol was not measured because the cooling effect above the skin would be difficult to quantify. Also, the temperature of the frozen swabs (−9.5°C) was colder than ice (∼0°C), the typical cold stimulus used in
W
561
Copyright © 2014 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
