Thomas M. Hemmerling

Evidence basis for regional anesthesia in multidisciplinary fast-track surgical care pathways.

Fast-track programs have been developed with the aim to reduce perioperative surgical stress and facilitate patients recovery after surgery. Potentially, regional anesthesia and analgesia techniques may offer physiological advantages to support fast-track methodologies in different type of surgeries. The aim of this article was to identify and discuss potential advantages offerred by regional anesthesia and analgesia techniques to fast-track programs. In the first section, the impact of regional anesthesia on the main elements of fast-track surgery is addressed. In the second section, procedure-specific fast-track programs for colorectal, hernia, esophageal, cardiac, vascular, and orthopedic surgeries are presented. For each, regional anesthesia and analgesia techniques more frequently used are discussed. Furthermore, clinical studies, which included regional techniques as elements of fast-track methodologies, were identified. The impact of epidural and paravertebral blockade, spinal analgesia, peripheral nerve blocks, and new regional anesthesia techniques on main procedure-specific postoperative outcomes is discussed. Finally, in the last section, implementations required to improve the role of regional anesthesia in the context of fast-track programs are suggested, and issues not yet addressed are presented.

Brief review: Neuromuscular monitoring: an update for the clinician.

PurposeTo review established techniques and to provide an update on new methods for clinical monitoring of neuromuscular function relevant to anesthesia.SourceA PubMed search of relevant article for the period 1985–2005 was undertaken, and bibliographies were scanned for additional sources.Principal findingsThere is no substitute for objective neuromuscular monitoring; for research purposes, mechanomyography (MMG) is the gold standard; however, the most versatile method in the clinical setting is acceleromyography since it can be applied at various muscles and has a long track record of clinical utility. Kinemyography is valid to monitor recovery of neuromuscular transmission at the adductor pollicis muscle (AP), whereas phonomyography is easy to apply to various muscles and shows promising agreement with MMG. Monitoring of the corrugator supercilii muscle (CS) may be used to determine the earliest time for tracheal intubation as it reflects laryngeal relaxation better than monitoring at the A P. Recovery of neuromuscular transmission is best monitored at the A P, since it is the last muscle to recover from neuromuscular blockade (NMB). If train-of-four (TOF) stimulation is used, a TOF-ratio > 0.9 should be the target before awakening the patient. If surgery or the type of anesthesia necessitates NMB of a certain degree, e.g., TOF-ratio = 0.25, monitoring of muscles which best reflect the degree of NMB at the surgical site is preferable.ConclusionObjective methods should be used to monitor neuromuscular function in clinical anesthesia. Acceleromyography offers the best compromise with respect to ease of use, practicality, versatility, precision and applicability at various muscles. The CS is the optimal muscle to determine the earliest time for intubation, e.g., for rapid sequence induction.RésuméObjectifFaire le point sur les techniques établies et fournir une mise à jour sur les nouvelles méthodes de monitorage clinique de la fonction neuromusculaire pertinentes à l’anesthésie.SourceUne recherche PubMed d’articles pertinents de la période 1985–2005 a été effectuée, et des bibliographies ont été fouillées afin d’obtenir des sources supplémentaires.Constatations principalesIl n’existe pas de substitut pour le monitorage neuromusculaire objectif; à des fins de recherche, la méchanomyographie (MMG) est l’étalon or (« gold standard »); l’accéléromyographie est la méthode la plus polyvalente dans un environnement clinique, étant donné qu’elle peut être appliquée à divers muscles et a depuis longtemps fait ses preuves d’utilité clinique. La kinémyographie est valable pour surveiller la récupération de la transmission neuromusculaire au niveau du muscle adducteur du pouce (AP), alors que la phonomyographie est facile à appliquer à divers muscles et démontre un accord prometteur avec la MMG. Le monitorage du muscle sourcilier (CS) peut être utilisé afin de déterminer le temps le plus court pour l’intubation trachéale, étant donné qu’il reflète la curarisation du larynx mieux que le monitorage de l’AP. La récupération de la transmission neuromusculaire est le mieux surveillée au niveau de l’AP, vu que ce muscle est le dernier à se rétablir d’un blocage neuromusculaire (BNM). Si une stimulation en train-de-quatre (TOF) est utilisée, un ratio de TOF > 0,9 devrait être l’objectif avant de réveiller le patient. Si la chirurgie ou le type d’anesthésie nécessite un BNM d’un certain degré, par exemple, un ratio de TOF = 0,25, le monitorage des muscles qui reflète le mieux le degré de BNM au site chirurgical est préférable.ConclusionDes méthodes objectives devraient être utilisées pour le monitorage de la fonction neuromusculaire en anesthésie clinique. L’accéléromyographie offre le meilleur compromis si l’on considère la facilité d’utilisation, l’aspect pratique, la flexibilité, la précision ainsi que l’applicabilité à divers muscles. Le CS est le muscle optimal pour déterminer le temps le plus court pour l’intubation, par exemple lors d’une induction à séquence rapide.

Reduced cerebral oxygen saturation during thoracic surgery predicts early postoperative cognitive dysfunction.

BACKGROUND The objective of this prospective study is to determine cognitive dysfunction after thoracic surgery. METHODS Seventy-six patients undergoing thoracic surgery with single-lung ventilation (SLV) of an expected duration of >45 min were enrolled. Monitoring consisted of standard clinical parameters and absolute oximetry (S(ct)O(2)). The Mini-Mental State Exam (MMSE) test was used to assess cognitive function before operation and at 3 and 24 h after operation. Data were analysed using Spearman correlation test; risks for cognitive dysfunction were expressed as odds ratios. P<0.05 and data are presented as median (interquartile range). RESULTS One patient was excluded from the study. S(ct)O(2) during SLV decreased to critical values of <65%, 60%, and 55% in 40 (53%), 15 (20%), and 5 patients (7%), respectively. Twenty-two patients (29%) had a decrease of MMSE>2 points 3 h after surgery, eight patients (10%) had a decrease of MMSE>2 points 24 h after surgery. Postoperative cognitive dysfunction correlated at r(2)=0.272, 0.285, 0.297 with patient exposure times to S(ct)O(2)<65% (P=0.018), <60% (P=0.013), <55% (P=0.010), respectively. The odds ratios of developing early cognitive dysfunction ranged from 2.03 (95% CI: 0.74-5.59) for a short (<5 min) exposure to S(ct)O(2)<65% to a maximum of 9.56 (95% CI: 1.75-52.13) when S(ct)O(2) was <60% for more than 30 min. CONCLUSIONS Early cognitive dysfunction after thoracic surgery with SLV is positively related to intraoperative decline of S(ct)O(2).

Sugammadex - A short review and clinical recommendations for the cardiac anesthesiologist

This review outlines the basic pharmacodynamic and pharmacokinetic properties of sugammadex for the cardiac anesthesiologist. It describes the different clinical scenarios when sugammadex can be used during cardiac surgery and gives clinical recommendations. Sugammadex is a unique reversal drug that binds a chemical complex with rocuronium and vecuronium, by which the neuromuscular blockade is quickly reversed. It is free of any clinical side-effects and doses of 2 mg/kg or more reliably reverse neuromuscular blockade within 5-15 min, depending on the depth of the neuromuscular blockade. Doses below 2 mg/kg should be avoided at any time because of the inherent risk of recurarization. Sugammadex should not replace good clinical practice--titration of neuromuscular blocking drugs to clinical needs and objective monitoring of neuromuscular blockade in the operating room or intensive care unit. Neuromuscular transmission should be determined in all patients before sugammadex is considered and 5 min after its administration to ensure that extubation is performed with normal neuromuscular transmission.

Tako-Tsubo syndrome in an anaesthetised patient undergoing arthroscopic knee surgery.

We present a case of stress-induced myocardial stunning, also known as Tako-Tsubo syndrome, in an anaesthetised patient undergoing arthroscopic replacement of the cruciate ligament. The patients (44 y male, ASA class II) had a history of hypertension with no other known disease. He underwent a femoral nerve block with 20 ml of 0.5% ropivacaine before receiving a balanced general anaesthesia (propofol induction, sevoflurane maintenance, 10 microg/kg sufentanil). Ten min after the beginning of surgery during endoscopic intra-articular manipulation, the patient suffered from bradycardia and hypotension; following the administration of ephedrine and atropine, he developed tachycardia, hypertension and ST segment depression. Subsequently, his systemic blood pressure dropped necessitating inotropic drug support and--later--intraaortic balloon counterpulsation; a TEE revealed no evidence of hypovolemia, anterior and antero-septal hypokinesia with an ejection fraction of 25%. Surgery was finished whilst stabilising the patient haemodynamically. Postoperative cardiac enzymes showed little elevation, an emergency coronary angiogram apical akinesia with typical ballooning and basal hyperkinesias, compatible with Tako-Tsubo syndrome. The patients postoperative course was uneventful. We theorize that stress caused by sudden surgical pain stimulus (introduction of the endoscope into the articulation), superficial anaesthesia and insufficient analgesia created a stressful event which probably might have caused a catecholamine surge as basis of Tako-Tsubo syndrome.

Comparison of four different display designs of a novel anaesthetic monitoring system, the ‘integrated monitor of anaesthesia (IMA™)’

BACKGROUND A novel monitoring system (integrated monitor of anaesthesia, IMA) which integrates three components of general anaesthesia on one single display was developed. The focus of this study was to evaluate the performance and user-friendliness of four different display designs. METHODS Four interface displays of the IMA were developed, including one numerical, one numerical and graphical (mixed numerical-graphical), one only graphical, and one an advanced two-dimensional graphical display. Each of the four displays was evaluated in a random order by 10 staff anaesthetists and 10 residents/fellows using a set of five scenarios. Scenarios involved one or more abnormal variables that participants had to verbally phrase. For each interface test, reaction time, response accuracy, and NASA-Task Load Index were measured and compared. RESULTS The numerical, graphical, and advanced-graphical interfaces yielded similar median reaction times, respectively, 7.99 s (5.15-10.79), 8.21 s (6.20-11.88), and 9.43 s (6.19-13.3). Reaction times were significantly shorter (P<0.006) with the mixed numerical-graphical interface: 6.26 s (4.52-8.32). The correct response rate was significantly lower in the graphical interface. The three others presented no statistical difference when compared among each other. The mixed numerical-graphical interface yielded a significantly lower NASA-TLX than the numerical and the advanced-graphical interfaces (19/100 vs 34/100, P<0.003). CONCLUSIONS A mixed numerical-graphical display design appears to present the best results in terms of user reaction times, response accuracy, and performance index when detecting abnormal critical events.

Transversus abdominal plane block for postoperative analgesia: a systematic review and meta-analysis of randomized-controlled trials.

PurposeThe transversus abdominal plane (TAP) block has been described as an effective pain control technique after abdominal surgery. We performed a systematic review and meta-analysis of randomized-controlled trials (RCTs) to account for the increasing number of TAP block studies appearing in the literature. The primary outcome we examined was the effect of TAP block on the postoperative pain score at six, 12, and 24 hr. The secondary outcome was 24-hr morphine consumption.SourceWe searched the United States National Library of Medicine database, the Excerpta Medica database, and the Cochrane Central Register of Controlled Clinical Studies and identified RCTs focusing on the analgesic efficacy of TAP block compared with a control group [i.e., placebo, epidural analgesia, intrathecal morphine (ITM), and ilioinguinal nerve block after abdominal surgery]. Meta-analyses were performed on postoperative pain scores at rest at six, 12, and 24 hr (visual analogue scale, 0-10) and on 24-hr opioid consumption.Principal findingsIn the 51 trials identified, compared with placebo, TAP block reduced the VAS for pain at six hours by 1.4 (95% confidence interval [CI], −1.9 to −0.8; P < 0.001), at 12 hr by 2.0 (95% CI, −2.7 to −1.4; P < 0.001), and at 24 hr by 1.2 (95% CI, −1.6 to −0.8; P < 0.001). Similarly, compared with placebo, TAP block reduced morphine consumption at 24 hr after surgery (mean difference, −14.7 mg; 95% CI, −18.4 to −11.0; P < 0.001). We observed this reduction in pain scores and morphine consumption in the TAP block group after gynecological surgery, appendectomy, inguinal surgery, bariatric surgery, and urological surgery. Nevertheless, separate analysis of the studies comparing ITM with TAP block revealed that ITM seemed to have a greater analgesic efficacy.ConclusionsThe TAP block can play an important role in the management of pain after abdominal surgery by reducing both pain scores and 24-hr morphine consumption. It may have particular utility when neuraxial techniques or opioids are contraindicated.RésuméObjectifLe bloc dans le plan du muscle transverse de l’abdomen (ou TAP bloc) a été décrit comme une technique efficace de contrôle de la douleur après une chirurgie abdominale. Nous avons réalisé une revue systématique et une méta-analyse des études randomisées contrôlées (ERC) pour faire un état des lieux du nombre croissant d’études sur le TAP bloc qui s’ajoutent à la littérature. Le critère d’évaluation principal était l’effet d’un TAP bloc sur les scores de douleur postopératoire à six, 12 et 24 h. Le critère d’évaluation secondaire était la consommation de morphine à 24 h.SourceNous avons effectué des recherches dans la base de données de la Bibliothèque nationale américaine de médecine (United States National Library of Medicine) ainsi que dans le Registre central Cochrane des études cliniques contrôlées (Cochrane Central Register of Controlled Clinical Studies). Nous avons ensuite identifié les ERC se concentrant sur l’efficacité analgésique des TAP blocs par rapport à un groupe témoin [c.-à-d. placebo, analgésie péridurale, morphine intrathécale (MIT) et bloc nerveux ilio-inguinal] après une chirurgie abdominale. Des méta-analyses ont été réalisées en examinant les scores de douleur postopératoire au repos à six, 12 et 24 h (échelle visuelle analogique [EVA], 0-10) et la consommation d’opioïdes sur une période de 24 h.Constatations principalesParmi les 51 études identifiées, par rapport à un placebo, le TAP bloc a réduit le score de douleur de 1,4 sur l’EVA après six heures (intervalle de confiance [IC] 95 %, −1,9 à −0,8; P < 0,001), de 2,0 après 12 h (IC 95 %, −2,7 à −1,4; P < 0,001) et de 1,2 après 24 h (IC 95 %, −1,6 à −0,8; P < 0,001). De la même façon, par rapport au placebo, le TAP bloc a réduit la consommation de morphine à 24 h après la chirurgie (différence moyenne, −14,7 mg; IC 95 %, −18,4 à −11,0; P < 0,001). Nous avons observé cette réduction en matière de scores de douleur et de consommation de morphine dans le groupe TAP bloc après des chirurgies gynécologiques, des appendicectomies, des chirurgies inguinales, des chirurgies bariatriques et des chirurgies urologiques. Toutefois, une analyse séparée des études comparant la MIT au TAP bloc a révélé que la MIT semblait avoir une efficacité analgésique plus prononcée.ConclusionLe TAP bloc peut jouer un rôle important dans la prise en charge de la douleur après une chirurgie abdominale en réduisant les scores de douleur et la consommation de morphine à 24 h. Il pourrait être particulièrement utile lorsque l’utilisation de techniques neuraxiales ou les opioïdes sont contre-indiqués.

Comparison of success rates, learning curves, and inter-subject performance variability of robot-assisted and manual ultrasound-guided nerve block needle guidance in simulation

BACKGROUND This study focuses on a recently developed robotic nerve block system and its impact on learning regional anaesthesia skills. We compared success rates, learning curves, performance times, and inter-subject performance variability of robot-assisted vs manual ultrasound (US)-guided nerve block needle guidance. The hypothesis of this study is that robot assistance will result in faster skill acquisition than manual needle guidance. METHODS Five co-authors with different experience with nerve blocks and the robotic system performed both manual and robot-assisted, US-guided nerve blocks on two different nerves of a nerve phantom. Ten trials were performed for each of the four procedures. Time taken to move from a shared starting position till the needle was inserted into the target nerve was defined as the performance time. A successful block was defined as the insertion of the needle into the target nerve. Average performance times were compared using analysis of variance. P<0.05 was considered significant. Data presented as mean (standard deviation). RESULTS All blocks were successful. There were significant differences in performance times between co-authors to perform the manual blocks, either superficial (P=0.001) or profound (P=0.0001); no statistical difference between co-authors was noted for the robot-assisted blocks. Linear regression indicated that the average decrease in time between consecutive trials for robot-assisted blocks of 1.8 (1.6) s was significantly (P=0.007) greater than the decrease for manual blocks of 0.3 (0.3) s. CONCLUSIONS Robot assistance of nerve blocks allows for faster learning of needle guidance over manual positioning and reduces inter-subject performance variability.

First robotic tracheal intubations in humans using the Kepler intubation system

BACKGROUND Intubation is one of the most important anaesthetic skills. We developed a robotic intubation system (Kepler intubation system, KIS) for oral tracheal intubation. METHODS In this pilot study, 12 patients were enrolled after approval of the local Ethics board and written informed consent. The KIS consists of four main components: a ThrustMaster T.Flight Hotas X joystick (Guillemot Inc., New York, NY, USA), a JACO robotic arm (Kinova Rehab, Montreal, QC, Canada), a Pentax AWS video laryngoscope (Ambu A/S, Ballerup, Denmark), and a software control system. The joystick allows simulation of the wrist or arm movements of a human operator. The success rate of intubation and intubation times were measured. RESULTS Eleven men and one woman aged 66 yr were included in this study. Intubation was successful in all but one patient using KIS at a total time of [median (inter-quartile range; range)] 93 (87, 109; 76, 153) s; in one patient, fogging of the video laryngoscope prevented intubation using KIS. CONCLUSIONS We present the first human testing of a robotic intubation system for oral tracheal intubation. The success rate was high at 91%. Future studies are needed to assess the performance and safety of such a system.

Technical communication: First robotic ultrasound-guided nerve blocks in humans using the Magellan system.

BACKGROUND:Ultrasound-guided nerve blocks are becoming a standard of modern anesthesia. We developed a robotic system, Magellan, to perform nerve blocks using a remote control center. METHODS:Thirteen patients were enrolled in this pilot study. The Magellan system consists of 3 main components: a joystick, a robotic arm, and a software control system. The joystick allows simulation of wrist or arm movements of the proceduralist. After localization of the sciatic nerve, 35 mL of bupivacaine 0.25% was injected. The success rate of sciatic nerve blocks and block performance times (performance time = interval of time from the start of the ultrasound search for the nerve to the end of the injection of the drug; robotic time = interval of time from the identification of the nerve to the end of the injection of the drug) were determined. Data are presented as median (25th, 75th; minimal, maximal) and categorical data. RESULTS:Eight men and 5 women aged 34 years were included in this study. Nerve blocks were successful in all patients. A successful attempt was defined as the introduction of the needle into the nerve sheath; motor or sensory block was not used to determine the success rate. The nerve performance time was 189 seconds (150, 233; 90, 305), whereas the robotic time was 164 seconds (121, 210; 73, 271). CONCLUSIONS:We present the first human testing of a robotic ultrasound-guided nerve block system. The success rate was 100%. The total performance time was approximately 3 minutes to 4 minutes.