- Email: [email protected]
The concept of protective nerve stimulation for ultrasound guided nerve blocks
Medical Hypotheses 107 (2017) 72–73
Contents lists available at ScienceDirect
Medical Hypotheses journal homepage: www.elsevier.com/locate/mehy
The concept of protective nerve stimulation for ultrasound guided nerve blocks
MARK
⁎
Martin Ertmer , Edda Klotz, Jürgen Birnbaum Department of Anesthesiology and Intensive Care Medicine, Campus Charité Mitte and Campus Virchow-Klinikum, Charité – Universitätsmedizin Berlin, Berlin, Germany
A B S T R A C T Regional plexus and nerve blocks are a common technique in modern anesthesia. Since ultrasound machines are available in many departments, the role of nerve stimulation is highly discussed and different approaches to perform the blocks are taken into account. Common technique for electrical nerve stimulation is searching for a stimulating threshold of 0.4–0.5 mA using an impulse width of 0.1 ms. We present our hypothesis of using all possible information with a new concept of protective nerve stimulation together with first data supporting our theory. In protective nerve stimulation during ultrasound guided nerve blocks a fixed current of 1.0 mA (0.1 ms) is used without any change during block performance. The aim is no muscular twitches before and during injection. If this way of neuro-axial blocking brings suitable effects, we should consider new currency settings to perform safer blockades with a lower risk of nerve injuries and a high patient comfort, especially in bad visibility block situations.
Background In the last time, ultrasound became the more and more preferred tool for locating nerve structures to perform plexus and nerve blocks. In an ever-increasing number of publications, the advances of ultrasound are highlighted compared to “conventional” nerve blocks using electrical nerve stimulation and ultrasound is recommended to improve efficacy and reduce complications of plexus blocks [1]. Partially, the suitability of electrical nerve stimulation is called into question at all [2]. On the other hand, it should not be ignored that blockades utilizing nerve stimulation, in the hand of experienced anaesthesiologists can achieve comparable results regarding success rate, pain control and patient’s satisfaction [3]. Certainly, there is no doubt that the safe use of ultrasound in regional anaesthesia requires a lot of experience, anatomical knowledge and practical skills. Also against the background of our long-standing experience in ultrasound guided regional anaesthesia sometimes we are surprised at the unexpected muscle twitches that suddenly occur during puncture, when we use nerve stimulation at the same time. This muscle twitches are supposed to be accidental needle-nervecontacts or nerve punctures not visualized in ultra-sound. While needlenerve-contacts or nerve punctures may cause infectious nerve changes, axonal degeneration and histopathological changes they have to be avoided [4–6]. Vassilou and colleagues showed that a needle-nerve-
⁎
Corresponding author. E-mail address: [email protected] (M. Ertmer).
http://dx.doi.org/10.1016/j.mehy.2017.08.018 Received 10 April 2017; Accepted 14 August 2017 0306-9877/ © 2017 Elsevier Ltd. All rights reserved.
contact occurred in 85% using common electrical nerve stimulation [7]. That’s why we have to think about the used currents for electrical nerve stimulation. Hypothesis A hypothesis is postulated that according to low currency electrical nerve stimulation needle-nerve-contacts without motoric reaction occur [7] and a new type of electrical nerve stimulation (“protective nerve stimulation”) is needed. We suggest an ultrasound-guided blockade using a protective nerve stimulation and hypothesize that this can lead to effective blocks without getting motoric response before – lowering the risk of needle-nerve-contact. Namely, we try to prevent any nerve stimulation, in particular immediately before or during the injection of the local anaesthetic. For this we use a fixed stimulation current (1 mA; 0.1 ms, 2 Hz), which is not changed during the blockade at any time. In case of muscle twitches, we suggest to draw the needle back or correct its position until the twitching ends. Evaluation of the hypothesis/idea and empirical data Some former investigations showed, that a combination of ultrasound and electrical nerve stimulation could improve the needle nerve placement [8,9]. The latest study of Vassilou et al. in combination with our observations highlights the role of current and unexpected muscle
Medical Hypotheses 107 (2017) 72–73
M. Ertmer et al.
Fig. 1. Different nerve blocks were performed with and without protective nerve stimulation (without/with): N. saphenus (N = 12/ N = 1), N. ischiadicus (N = 9/N = 2), N. femoralis (N = 10/N = 2) and axillary plexus block (N = 8/N = 2).
twitches [7]. So we decided to conduct some blockades under protective nerve stimulation to see whether effective blocks using protective nerve stimulation are successful or not. We retrospectively analyzed 46 nerve blockades in four anatomical regions (N. saphenus, N. ischiadicus, N. femoralis and axillary access to brachial plexus) after approval of the local ethics committee. Seven of this nerve blocks were performed under protective nerve stimulation. All 46 blockades were claimed to be effective and no adverse events were reported (see Fig. 1).
If the protective nerve stimulation actually helps to prevent nerve injuries in our patients we cannot answer yet and it only can be the subject of further clinical investigation.
Consequences of the hypothesis and discussion
Sources of grant
Conflict of interest Martin Ertmer, Edda Klotz and Jürgen Birnbaum don’t declare any conflicts.
Institutional founding.
In all cases, despite the relatively high current and the lack of muscular twitches on the nerve stimulation, the needle tip is so close to the nerve, that the local anaesthetic reaches the nerve structure safely. This clinical experience is consistent with the results of a clinical study we performed at our institution; where we found that, with correct ultrasound-guided needle tip positioning the electrical information seems to be skewed and doubtful regarding success rate of the block [10]. When the nerve or the needle tip can be identified in the ultrasound picture only uncertainly, we consider the electrical nerve stimulation as essential. The protective nerve stimulation seems to have the following advantages:
References [1] Klaastad O, Sauter AR, Dodgson MS. Brachial plexus block with or without ultrasound guidance. Curr Opin Anaesthesiol 2009;22(5):655–60. [2] Dillane D, Tsui BC. Is there still a place for the use of nerve stimulation? Paediatr Anaesth 2012;22(1):102–8. [3] Salem MH, Winckelmann J, Geiger P, Mehrkens HH, Salem KH. Electrostimulation with or without ultrasound-guidance in interscalene brachial plexus block for shoulder surgery. J Anesth 2012;26(4):610–3. [4] Wiesmann T, Borntrager A, Vassiliou T, Hadzic A, Wulf H, Muller HH, et al. Minimal current intensity to elicit an evoked motor response cannot discern between needlenerve contact and intraneural needle insertion. Anesth Analg 2014;118(3):681–6. [5] Wiesmann T, Steinfeldt T, Exner M, Nimphius W, De Andres J, Wulf H, et al. Intraneural injection of a test dose of local anesthetic in peripheral nerves – does it induce histological changes in nerve tissue? Acta Anaesthesiol Scand 2017;61(1):91–8. [6] Sen O, Sayilgan NC, Tutuncu AC, Bakan M, Koksal GM, Oz H. Evaluation of sciatic nerve damage following intraneural injection of bupivacaine, levobupivacaine and lidocaine in rats. Braz J Anesthesiol 2016;66(3):272–5. [7] Vassiliou T, Muller HH, Limberg S, De Andres J, Steinfeldt T, Wiesmann T. Risk evaluation for needle-nerve contact related to electrical nerve stimulation in a porcine model. Acta Anaesthesiol Scand 2016;60(3):400–6. [8] Vassiliou T, Eider J, Nimphius W, Wiesmann T, de Andres J, Muller HH, et al. Dual guidance improves needle tip placement for peripheral nerve blocks in a porcine model. Acta Anaesthesiol Scand 2012;56(9):1156–62. [9] Jochum D, Bondar A, Delaunay L, Egan M, Bouaziz H. One size does not fit all: proposed algorithm for ultrasonography in combination with nerve stimulation for peripheral nerve blockade. Br J Anaesth 2009;103(5):771–3. [10] Habicher M, Ocken M, Birnbaum J, Volk T. Electrical nerve stimulation for peripheral nerve blocks. Ultrasound-guided needle positioning and effect of 5% glucose injection. Anaesthesist 2009;58(10):986–91.
• increased •
protection from unwanted, especially multiple nerve puncture, when the needle tip is out of plane inadvertently or when the needle tip reaches a nerve structure which is not recognized as such in the ultrasound picture. The needle can be advanced in the direction of a structure from which the anaesthetist is not sure if this is a nerve indeed. The specific motor response can help to identify a specific nerve or portion of a nerve plexus in the ultrasound image.
Since we know that whether ultrasound nor electrical nerve stimulation can prevent wrong puncture or intraneural needle position and since we cannot be sure that nerve puncture or intraneural injection are harmless in all cases and since we are not able to get a perfect visualisation of the needle and of all structures in all patients, we would strongly recommend the protective nerve stimulation.
73
Contents lists available at ScienceDirect
Medical Hypotheses journal homepage: www.elsevier.com/locate/mehy
The concept of protective nerve stimulation for ultrasound guided nerve blocks
MARK
⁎
Martin Ertmer , Edda Klotz, Jürgen Birnbaum Department of Anesthesiology and Intensive Care Medicine, Campus Charité Mitte and Campus Virchow-Klinikum, Charité – Universitätsmedizin Berlin, Berlin, Germany
A B S T R A C T Regional plexus and nerve blocks are a common technique in modern anesthesia. Since ultrasound machines are available in many departments, the role of nerve stimulation is highly discussed and different approaches to perform the blocks are taken into account. Common technique for electrical nerve stimulation is searching for a stimulating threshold of 0.4–0.5 mA using an impulse width of 0.1 ms. We present our hypothesis of using all possible information with a new concept of protective nerve stimulation together with first data supporting our theory. In protective nerve stimulation during ultrasound guided nerve blocks a fixed current of 1.0 mA (0.1 ms) is used without any change during block performance. The aim is no muscular twitches before and during injection. If this way of neuro-axial blocking brings suitable effects, we should consider new currency settings to perform safer blockades with a lower risk of nerve injuries and a high patient comfort, especially in bad visibility block situations.
Background In the last time, ultrasound became the more and more preferred tool for locating nerve structures to perform plexus and nerve blocks. In an ever-increasing number of publications, the advances of ultrasound are highlighted compared to “conventional” nerve blocks using electrical nerve stimulation and ultrasound is recommended to improve efficacy and reduce complications of plexus blocks [1]. Partially, the suitability of electrical nerve stimulation is called into question at all [2]. On the other hand, it should not be ignored that blockades utilizing nerve stimulation, in the hand of experienced anaesthesiologists can achieve comparable results regarding success rate, pain control and patient’s satisfaction [3]. Certainly, there is no doubt that the safe use of ultrasound in regional anaesthesia requires a lot of experience, anatomical knowledge and practical skills. Also against the background of our long-standing experience in ultrasound guided regional anaesthesia sometimes we are surprised at the unexpected muscle twitches that suddenly occur during puncture, when we use nerve stimulation at the same time. This muscle twitches are supposed to be accidental needle-nervecontacts or nerve punctures not visualized in ultra-sound. While needlenerve-contacts or nerve punctures may cause infectious nerve changes, axonal degeneration and histopathological changes they have to be avoided [4–6]. Vassilou and colleagues showed that a needle-nerve-
⁎
Corresponding author. E-mail address: [email protected] (M. Ertmer).
http://dx.doi.org/10.1016/j.mehy.2017.08.018 Received 10 April 2017; Accepted 14 August 2017 0306-9877/ © 2017 Elsevier Ltd. All rights reserved.
contact occurred in 85% using common electrical nerve stimulation [7]. That’s why we have to think about the used currents for electrical nerve stimulation. Hypothesis A hypothesis is postulated that according to low currency electrical nerve stimulation needle-nerve-contacts without motoric reaction occur [7] and a new type of electrical nerve stimulation (“protective nerve stimulation”) is needed. We suggest an ultrasound-guided blockade using a protective nerve stimulation and hypothesize that this can lead to effective blocks without getting motoric response before – lowering the risk of needle-nerve-contact. Namely, we try to prevent any nerve stimulation, in particular immediately before or during the injection of the local anaesthetic. For this we use a fixed stimulation current (1 mA; 0.1 ms, 2 Hz), which is not changed during the blockade at any time. In case of muscle twitches, we suggest to draw the needle back or correct its position until the twitching ends. Evaluation of the hypothesis/idea and empirical data Some former investigations showed, that a combination of ultrasound and electrical nerve stimulation could improve the needle nerve placement [8,9]. The latest study of Vassilou et al. in combination with our observations highlights the role of current and unexpected muscle
Medical Hypotheses 107 (2017) 72–73
M. Ertmer et al.
Fig. 1. Different nerve blocks were performed with and without protective nerve stimulation (without/with): N. saphenus (N = 12/ N = 1), N. ischiadicus (N = 9/N = 2), N. femoralis (N = 10/N = 2) and axillary plexus block (N = 8/N = 2).
twitches [7]. So we decided to conduct some blockades under protective nerve stimulation to see whether effective blocks using protective nerve stimulation are successful or not. We retrospectively analyzed 46 nerve blockades in four anatomical regions (N. saphenus, N. ischiadicus, N. femoralis and axillary access to brachial plexus) after approval of the local ethics committee. Seven of this nerve blocks were performed under protective nerve stimulation. All 46 blockades were claimed to be effective and no adverse events were reported (see Fig. 1).
If the protective nerve stimulation actually helps to prevent nerve injuries in our patients we cannot answer yet and it only can be the subject of further clinical investigation.
Consequences of the hypothesis and discussion
Sources of grant
Conflict of interest Martin Ertmer, Edda Klotz and Jürgen Birnbaum don’t declare any conflicts.
Institutional founding.
In all cases, despite the relatively high current and the lack of muscular twitches on the nerve stimulation, the needle tip is so close to the nerve, that the local anaesthetic reaches the nerve structure safely. This clinical experience is consistent with the results of a clinical study we performed at our institution; where we found that, with correct ultrasound-guided needle tip positioning the electrical information seems to be skewed and doubtful regarding success rate of the block [10]. When the nerve or the needle tip can be identified in the ultrasound picture only uncertainly, we consider the electrical nerve stimulation as essential. The protective nerve stimulation seems to have the following advantages:
References [1] Klaastad O, Sauter AR, Dodgson MS. Brachial plexus block with or without ultrasound guidance. Curr Opin Anaesthesiol 2009;22(5):655–60. [2] Dillane D, Tsui BC. Is there still a place for the use of nerve stimulation? Paediatr Anaesth 2012;22(1):102–8. [3] Salem MH, Winckelmann J, Geiger P, Mehrkens HH, Salem KH. Electrostimulation with or without ultrasound-guidance in interscalene brachial plexus block for shoulder surgery. J Anesth 2012;26(4):610–3. [4] Wiesmann T, Borntrager A, Vassiliou T, Hadzic A, Wulf H, Muller HH, et al. Minimal current intensity to elicit an evoked motor response cannot discern between needlenerve contact and intraneural needle insertion. Anesth Analg 2014;118(3):681–6. [5] Wiesmann T, Steinfeldt T, Exner M, Nimphius W, De Andres J, Wulf H, et al. Intraneural injection of a test dose of local anesthetic in peripheral nerves – does it induce histological changes in nerve tissue? Acta Anaesthesiol Scand 2017;61(1):91–8. [6] Sen O, Sayilgan NC, Tutuncu AC, Bakan M, Koksal GM, Oz H. Evaluation of sciatic nerve damage following intraneural injection of bupivacaine, levobupivacaine and lidocaine in rats. Braz J Anesthesiol 2016;66(3):272–5. [7] Vassiliou T, Muller HH, Limberg S, De Andres J, Steinfeldt T, Wiesmann T. Risk evaluation for needle-nerve contact related to electrical nerve stimulation in a porcine model. Acta Anaesthesiol Scand 2016;60(3):400–6. [8] Vassiliou T, Eider J, Nimphius W, Wiesmann T, de Andres J, Muller HH, et al. Dual guidance improves needle tip placement for peripheral nerve blocks in a porcine model. Acta Anaesthesiol Scand 2012;56(9):1156–62. [9] Jochum D, Bondar A, Delaunay L, Egan M, Bouaziz H. One size does not fit all: proposed algorithm for ultrasonography in combination with nerve stimulation for peripheral nerve blockade. Br J Anaesth 2009;103(5):771–3. [10] Habicher M, Ocken M, Birnbaum J, Volk T. Electrical nerve stimulation for peripheral nerve blocks. Ultrasound-guided needle positioning and effect of 5% glucose injection. Anaesthesist 2009;58(10):986–91.
• increased •
protection from unwanted, especially multiple nerve puncture, when the needle tip is out of plane inadvertently or when the needle tip reaches a nerve structure which is not recognized as such in the ultrasound picture. The needle can be advanced in the direction of a structure from which the anaesthetist is not sure if this is a nerve indeed. The specific motor response can help to identify a specific nerve or portion of a nerve plexus in the ultrasound image.
Since we know that whether ultrasound nor electrical nerve stimulation can prevent wrong puncture or intraneural needle position and since we cannot be sure that nerve puncture or intraneural injection are harmless in all cases and since we are not able to get a perfect visualisation of the needle and of all structures in all patients, we would strongly recommend the protective nerve stimulation.
73