Originalien Anaesthesist 2014 DOI 10.1007/s00101-014-2361-4 Received: 26 February 2014 Revised: 26 June 2014 Accepted: 5 July 2014 © Springer-Verlag Berlin Heidelberg 2014
G. Eren · E. Altun · Y. Pektas · Y. Polat · H. Cetingok · G. Demir · D. Bilgi · Y. Tekdos · M. Dogan Department of Anesthesiology and Intensive Care, Bakirkoy Dr. Sadi Konuk Training and Research Hospital, Zuhuratbaba/Istanbul
To what extent can local anesthetics be reduced for infraclavicular block with ultrasound guidance? Introduction Ultrasound (US) guidance offers an alternative approach for regional nerve blocks, providing real-time visualization of the nerve-needle interaction. For operations concerning the upper extremities, an infraclavicular blockade (ICB) is the preferred method due to a lower complication potential just like the axillary brachial plexus block [1, 2]. The use of sonographic imaging makes it safe to guide the needle, decreasing the risk of damage to adjacent structures like the pleura and subclavian artery. Sandhu and Capan [3] have shown that ultrasound can be a valuable tool to assist ICB, increasing the success rate and lowering the incidence of complications. Many previous studies have reported success rates in the range of 44–90% in terms of quality of ICB using neurostimulation with or without US guidance [4, 5, 6, 7, 8]; however, successful neurostimulationguided ICB depends entirely on an exact distal stimulation, which may be difficult in 5–21% of patients [4, 8] and adequate stimulation does not always guarantee a successful block. Therefore, ultrasonic visualization of local anesthetic spread has been proposed as a reliable indicator for accurate injection and taking this into account, several studies have reported complete blocks in 90–95% of patients [3, 9]. It has been shown that US guidance to nerve blocks improves success rates [1, 2, 3, 4, 5, 6], decreases block onset times [10, 11] and reduces local anesthetic dose [12, 13]. The present study was designed to assess the adequacy of different amounts of local anesthetics in ICB under US guidance in conjunction with neurostimulation and
compare them to the conventional doses under neurostimulation alone. The hypothesis was that US guidance would reduce the amount of local anesthetics without any supplementation and decrease the execution time of the block.
Methods After approval of the institutional ethics committee and obtaining written informed consent from the patients, 100 eligible patients scheduled for surgery of the upper extremities were randomized into 5 groups by the computer-generated random-number method. All procedures followed were in accordance with the Helsinki Declaration of 1975. Exclusion criteria included clinically significant coagulopathy, infection at the injection site, known hypersensitivity to local anesthetics, severe pulmonary pathology, motor and sensory deficits in the operated extremity, age 65 years, a body mass index more than 35 kg/m−2 or less than 18 kg/m−2 or patient refusal of the procedure. When required, light sedation (1–3 mg of midazolam) was given before the block but no other sedation was administered until evaluation of the block was completed. If patients desired perioperative sedation it was planned to maintain a propofol infusion titrated up to 50 µg/kg/min intravenously. If the operation site was not fully anesthetized (as indicated by pain on incision), the block would be supplemented at that region locally by the surgeon. With standard monitoring (i.e. pulse oximetry, heart rate and noninvasive blood pressure measurement) all blocks
were performed using 50 mm 22-gauge Teflon-coated needles (B. Braun, Melsungen, Germany). The anesthetic solution consisted of equal volumes of 0.5% levobupivacaine and 1% prilocaine in all groups. The solution was administered in a single injection of 0.5 ml/kg up to a maximum of 40 ml in the neurostimulation (group NS) and the full-dose US groups (group FD), and the other groups were arranged to receive reduced doses relative to that amount: patients in group 30 received 30% reduced dose, which makes a dose of 0.35 ml/kg of the aforementioned local anesthetic solution. In group 50 a dose of 0.25 ml/kg and in group 70 0.15 ml/kg was used. In all groups, except the neurostimulation group, the neurovascular bundle was imaged in the lateral infraclavicular region with a 5–13 MHz multifrequency linear ultrasonic scanning probe (GE 12LRS, GE Medical Systems, Phoenix, Ariz.). The probe was placed in a parasagittal position below the clavicle medial to the coracoid process and adjusted to achieve a cross-sectional image of the axillary artery. Following identification of the axillary artery and the cords, with the needle in plane with the probe, the 22-gauge needle was advanced caudally and posteriorly to the axillary artery [7]. The local anesthetic solutions were administered once wrist or hand movement had been elicited (as described by Borgeat et al. [8]) with the neurostimulator (Multistimupleks, Pajunk, Germany) delivering a current (1 Hz for 0.1 ms)
G. Eren · E. Altun · Y. Pektas · Y. Polat · H. Cetingok · G. Demir · D. Bilgi · Y. Tekdos · M. Dogan Department of Anesthesiology and Intensive Care, Bakirkoy Dr. Sadi Konuk Training and Research Hospital, Zuhuratbaba/Istanbul
To what extent can local anesthetics be reduced for infraclavicular block with ultrasound guidance? Introduction Ultrasound (US) guidance offers an alternative approach for regional nerve blocks, providing real-time visualization of the nerve-needle interaction. For operations concerning the upper extremities, an infraclavicular blockade (ICB) is the preferred method due to a lower complication potential just like the axillary brachial plexus block [1, 2]. The use of sonographic imaging makes it safe to guide the needle, decreasing the risk of damage to adjacent structures like the pleura and subclavian artery. Sandhu and Capan [3] have shown that ultrasound can be a valuable tool to assist ICB, increasing the success rate and lowering the incidence of complications. Many previous studies have reported success rates in the range of 44–90% in terms of quality of ICB using neurostimulation with or without US guidance [4, 5, 6, 7, 8]; however, successful neurostimulationguided ICB depends entirely on an exact distal stimulation, which may be difficult in 5–21% of patients [4, 8] and adequate stimulation does not always guarantee a successful block. Therefore, ultrasonic visualization of local anesthetic spread has been proposed as a reliable indicator for accurate injection and taking this into account, several studies have reported complete blocks in 90–95% of patients [3, 9]. It has been shown that US guidance to nerve blocks improves success rates [1, 2, 3, 4, 5, 6], decreases block onset times [10, 11] and reduces local anesthetic dose [12, 13]. The present study was designed to assess the adequacy of different amounts of local anesthetics in ICB under US guidance in conjunction with neurostimulation and
compare them to the conventional doses under neurostimulation alone. The hypothesis was that US guidance would reduce the amount of local anesthetics without any supplementation and decrease the execution time of the block.
Methods After approval of the institutional ethics committee and obtaining written informed consent from the patients, 100 eligible patients scheduled for surgery of the upper extremities were randomized into 5 groups by the computer-generated random-number method. All procedures followed were in accordance with the Helsinki Declaration of 1975. Exclusion criteria included clinically significant coagulopathy, infection at the injection site, known hypersensitivity to local anesthetics, severe pulmonary pathology, motor and sensory deficits in the operated extremity, age 65 years, a body mass index more than 35 kg/m−2 or less than 18 kg/m−2 or patient refusal of the procedure. When required, light sedation (1–3 mg of midazolam) was given before the block but no other sedation was administered until evaluation of the block was completed. If patients desired perioperative sedation it was planned to maintain a propofol infusion titrated up to 50 µg/kg/min intravenously. If the operation site was not fully anesthetized (as indicated by pain on incision), the block would be supplemented at that region locally by the surgeon. With standard monitoring (i.e. pulse oximetry, heart rate and noninvasive blood pressure measurement) all blocks
were performed using 50 mm 22-gauge Teflon-coated needles (B. Braun, Melsungen, Germany). The anesthetic solution consisted of equal volumes of 0.5% levobupivacaine and 1% prilocaine in all groups. The solution was administered in a single injection of 0.5 ml/kg up to a maximum of 40 ml in the neurostimulation (group NS) and the full-dose US groups (group FD), and the other groups were arranged to receive reduced doses relative to that amount: patients in group 30 received 30% reduced dose, which makes a dose of 0.35 ml/kg of the aforementioned local anesthetic solution. In group 50 a dose of 0.25 ml/kg and in group 70 0.15 ml/kg was used. In all groups, except the neurostimulation group, the neurovascular bundle was imaged in the lateral infraclavicular region with a 5–13 MHz multifrequency linear ultrasonic scanning probe (GE 12LRS, GE Medical Systems, Phoenix, Ariz.). The probe was placed in a parasagittal position below the clavicle medial to the coracoid process and adjusted to achieve a cross-sectional image of the axillary artery. Following identification of the axillary artery and the cords, with the needle in plane with the probe, the 22-gauge needle was advanced caudally and posteriorly to the axillary artery [7]. The local anesthetic solutions were administered once wrist or hand movement had been elicited (as described by Borgeat et al. [8]) with the neurostimulator (Multistimupleks, Pajunk, Germany) delivering a current (1 Hz for 0.1 ms)
