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Postoperative residual neuromuscular block (train of four ratio0.9) is an outcome-relevant problem in balanced anesthesia, which increases postoperative morbidity and mortality. Implementation of medium and short-acting muscle relaxants, quantitative neuromuscular monitoring and pharmacological reversal of muscle relaxation reduce the incidence of residual neuromuscular block. The question arises whether this is suitable to create a pragmatic algorithm integrating these three individual methods to reduce paralysis-associated complications?A selective literature search was carried out in PubMed and guidelines of national specialist societies were searched using special terms.The incidence of residual neuromuscular block varied among the studies but was as high as 93%. Using calibrated acceleromyography it is possible to identify a residual relaxation with a negative predictive value of 97% (95% confidence interval, CI 83-100%). Reversal by administration of the acetylcholinesterase inhibitor neostigmine reduces the incidence of residual neuromuscular block to 15.4%, in combination with calibrated acceleromyography to 3.3%. Reversal with sugammadex can nearly completely eliminate residual neuromuscular block. Quantitative neuromuscular monitoring and pharmacological reversal can be suitably integrated into a stage-based, pragmatic treatment algorithm.The algorithm-based concept of quantitative neuromuscular monitoring and pharmacological reversal using neostigmine and sugammadex enables residual neuromuscular block to be treated within 10 min before extubation of the patient. Ongoing educational programs are essential for implementation of modern muscle relaxant management concepts. Quantitative neuromuscular monitoring should be mandatory for all patients receiving neuromuscular blocking drugs. It would be desirable that German-speaking societies for anesthesiology make appropriate recommendations in guidelines.

Die Allgemeinanästhesie setzt sich aus einem Medikamentencocktail zusammen, das aus einem Hypnotikum, einem Muskelrelaxans sowie einem Analgetikum besteht. Die Analgetika sind der Opioidgruppe zugeordnet (z. B. Fentanyl oder Sufentanil). Alternativ kann das Opioid auch durch das Nicht-Opioid S(+)-Ketamin ersetzt werden. Studien der letzten Jahre verweisen allerdings auf mögliche unerwünschte Interaktionen zwischen Ketamin und einem Muskelrelaxans im Sinne einer verlängerten neuromuskulären Restblockade. Ziel der Studie war es daher, die Wirkung des Muskelrelaxans Mivacurium in Kombination mit S(+)-Ketamin versus Sufentanil auf die Muskelrelaxation zu evaluieren. Eingeschlossen wurden 120 Patienten, welche sich unfallchirurgischen oder orthopädischen Eingriffen unterzogen. Im Rahmen der operativen Eingriffe wurde eine total intravenöse Anästhesie durchgeführt, wobei in beiden Gruppen Propofol als Hypnotikum und Mivacurium als Muskelrelaxans verwendet wurden. Als Analgetikum wurde in Gruppe A (60 Patienten) S(+)-Ketamin und in Gruppe B (60 Patienten) Sufentanil verabreicht. Die Patienten wurden dabei randomisiert in die beiden Gruppen A und B aufgeteilt. Ein Patientenausschluss war im Rahmen der Studie nicht notwendig. Die beiden Patientengruppen unterschieden sich nicht bezüglich biometrischer Daten und der Aufteilung in die Kategorien nach ASA. Die mittlere Zeitspanne vom Injektionsende des Muskelrelaxans bis zur 25%igen Erholung der neuromuskulären Blockade (DUR25) betrug in der Ketamingruppe 22,1 Minuten und war damit statistisch signifikant verlängert im Vergleich zum Mittelwert in der Sufentanilgruppe mit 19,8 Minuten. Die Relaxationsmessung zur Kontrolle der neuromuskulären Reizübertragung an der motorischen Endplatte (Train-of-Four, TOF, -Stimulation) ergab ebenfalls statistisch verlängerte Erholungszeiten um durchschnittlich 11%. Die mittleren TOF50%-Werte (50%ige Erholung der neuromuskulären Relaxierung) errechneten sich zu 13,4 (Ketamingruppe) vs 11,9 Minuten (Sufentanilgruppe), die mittleren TOF70%-Werte (70%ige Erholung der neuromuskulären Relaxierung) zu 18,8 (Ketamingruppe) vs 16,7 Minuten (Sufentanilgruppe). Zuletzt wiesen auch die Mittelwerte für TOF80% (80%ige Erholung) in der Ketamingruppe mit 20,2 Minuten im Vergleich zur Sufentanilgruppe mit 18,2 Minuten eine statistisch signifikante Differenz auf. In der vorliegenden Studie konnte nachgewiesen werden, dass sich in vier der neun erhobenen Relaxationsgraden (DUR 25%, TOF50%, TOF70%, TOF80%) die Ketamin-Mivacurium-Gruppe statistisch signifikant von der Sufentanil-Mivacurium-Gruppe unterscheidet. Gleichzeitig ergab sich ein statistischer Trend (p 0,10) bezüglich der Relaxierungsgrade T1_5%-25%, T1_25%-75% (Erholungsindex), TOF90% und TOF100%. Die Resultate belegen somit die Hypothese eines verlängerten neuromuskulären Blocks durch Mivacurium in Gegenwart von S(+)-Ketamin. Als positiver Nebenbefund war unter S(+)-Ketamin eine stabile Kreislaufsituation zu verzeichnen, so dass hier möglicherweise ein Vorteil gegenüber anderen Therapieregimen erwächst. Wenngleich die hier präsentierten Befunde klinisch womöglich nicht als bedeutsam einzustufen sind, sollte dennoch auf das potentielle Risiko unerwünschter neuromuskulärer Restblockaden bzw. die damit assoziierten postoperativen Komplikationen verwiesen werden. Aus diesem Grund erscheint eine routinierte objektivierte Messung der Relaxierung im klinischen Alltag sinnvoll. Weiterführende Untersuchungen zur Vergleichbarkeit der muskelrelaxierenden Wirkung des Razemats Ketamin und seines Enantiomers S(+)-Ketamin sind wichtige zukünftige Projekte. Molekularbiologische Analysen sind zudem einzufordern, um die Wirkmechanismen der Mivacurium-Ketamin-Interaktion im Detail darzulegen., General anaesthesia is composed of a cocktail of drugs, including a hypnotic agent, a muscle relaxant and an analgesic. The analgesics belong to the opioid class of drugs (e.g. fentanyl or sufentanil). Alternatively, the opioid may also be replaced by the non-opioid drug, S(+)-ketamine. Studies over the past few years have demonstrated, however, that there may be undesirable interactions between ketamine and a muscle relaxant, leading to excessively prolonged neuromuscular blockage. The aim of this study, therefore, was to evaluate the effects of the muscle relaxant mivacurium in combination with S(+)-ketamine versus sufentanil with respect to muscular relaxation. 120 patients were included in the study who underwent surgery in either trauma or orthopaedic medicine. During the surgical procedures, an intravenous general anaesthesia was administered, with both groups receiving propofol as the hypnotic agent, and mivacurium as the muscle relaxant. As the analgesic, S(+)-ketamine was used in group A (60 patients) and sufentanil was used in group B (60 patients). The patients were randomly allocated to one of group A or group B. Patient exclusion criteria did not apply for this study. The two patient groups do not show differences with regards to biometric data or their distribution into categories according to the ASA. The average time period from the end of muscle relaxant injection to a 25% recovery from the neuromuscular blockage (DUR25) was 22.1 minutes in the ketamine group; this showed significantly increased time when compared with the average time for the sufentanil group, at 19.8 minutes. The relaxation measurement taken as a control of neuromuscular transfer of stimuli to the motor end plate (train-of-four; TOF stimulation) similarly produced a statistically significant increase in the recovery times, on average by 11%. The average TOF-50% value (50% recovery in neuromuscular relaxation) was calculated at 13.4 (for the ketamine group) vs. 11.9 minutes (for the sufentanil group); the average TOF-70% value (70% recovery in neuromuscular relaxation) was 18.8 (for the ketamine group) vs. 16.7 minutes (for the sufentanil group). Finally, the average values for TOF-80% (80% recovery) also showed a significant difference, at 20.2 minutes in the ketamine group, compared with 18.2 minutes in the sufentanil group. It could be proven in this study that there were statistical differences in four of the nine relaxation grades investigated (DUR-25%; TOF-50%; TOF-70%; TOF-80%) between the ketamine-mivacurium group and the sufentanil-mivacurium group. Similarly, there was a statistical trend (p 0.10) with relation to the grade of relaxation T1_5%-25%, T1_25%-75% (recovery index), TOF-90% and TOF-100%. As such, the results provide evidence to support the hypothesis of prolonged neuromuscular block by mivacurium when used in combination with S(+)-ketamine. A positive, additional finding was that of a stable circulatory situation when S(+)-ketamine was used, such that this might represent an advantage over other treatment regimes. Although the findings presented in this paper may not be classified as clinically significant, the possible risk of undesired prolonged neuromuscular blockade or the associated postoperative complications should be pointed out. For this reason, a routine objective measurement of the relaxation in routine clinical practice would be beneficial. Further investigations on the comparability of muscle relaxant effects of the ketamine racemate and its enantiomer S(+)-ketamine represent important future projects. Molecular biological analyses should also to encouraged in order to determine the mechanisms of action of the mivacurium-ketamine interaction in detail.

Neuromuscular blockade (TOF count = 0) can improve tracheal intubation and microlaryngeal surgery. It is also frequently used in many surgical fields including both nonlaparoscopic and laparoscopic surgery to improve surgical conditions and to prevent sudden muscle contractions. Currently there is a controversy regarding the need and the clinical benefits of deep neuromuscular blockade for different surgical procedures. Deep neuromuscular relaxation improves laparoscopic surgical space conditions only marginally when using low intra-abdominal pressure. There is no outcome-relevant advantage of low compared to higher intra-abdominal pressures, but worsen the surgical conditions. Postoperative, residual curarisation can be avoided by algorithm-based pharmacological reversing and quantitative neuromuscular monitoring.

Even small degrees of residual neuromuscular blockade, i. e. a train-of-four (TOF) ratio0.6, may lead to clinically relevant consequences for the patient. Especially upper airway integrity and the ability to swallow may still be markedly impaired. Moreover, increasing evidence suggests that residual neuromuscular blockade may affect postoperative outcome of patients. The incidence of these small degrees of residual blockade is relatively high and may persist for more than 90 min after a single intubating dose of an intermediately acting neuromuscular blocking agent, such as rocuronium and atracurium. Both neuromuscular monitoring and pharmacological reversal are key elements for the prevention of postoperative residual blockade.

Avoiding pain, agitation and delirium as well as avoiding unnecessary deep sedation is a powerful yet challenging strategy in critical care medicine. A number of interactions between cerebral function and respiratory function should be regarded in patients with respiratory failure and mechanical ventilation. A cooperative sedation strategy (i.e. patient is awake and free of pain and delirium) is feasible in many patients requiring invasive mechanical ventilation. Especially patients with mild acute respiratory distress syndrome (ARDS) seem to benefit from preserved spontaneous breathing. While completely disabling spontaneous ventilation with or without neuromuscular blockade is not a standard strategy in ARDS, it might be temporarily required in patients with severe ARDS, who have substantial dyssynchrony or persistent hypoxaemia. Since pain, agitation and delirium compromise respiratory function they should also be regarded during noninvasive ventilation and during ventilator weaning. Pharmacological sedation can have favourable effects in these situations, but should not be given routinely or uncritically.

The effect of muscle relaxants varies among people and the extent, the duration and recovery from the neuromuscular block varies. Clinical tests cannot determine the effect of muscle relaxants which is only possible with neuromuscular monitoring. The relaxometry procedure measures the muscular response to electrical stimulation of the corresponding motor nerve and the adductor pollicis muscle is mostly used; however, this muscle is not representative for other muscle groups, such as the muscles of the larynx and diaphragm. The muscles of the larynx and diaphragm are more resistant against nondepolarizing muscle relaxants than the adductor pollicis muscle. The train of four (TOF) is used at the beginning of surgery for monitoring of the optimal time for tracheal intubation; moreover, the TOF is used during surgery for monitoring of the muscle blockade and at the end of surgery for monitoring recovery. Monitoring of deep muscular blockades, however, is only possible with the posttetanic count (PTC) when there are no TOF counts. The PTC allows repetition and higher doses of muscle relaxants during abdominal surgery; therefore, conditions for surgery are optimal and cumulation of muscle relaxants is avoided.

Aspiration is a feared complication of anesthesia and is accompanied by increased morbidity and mortality. Rapid sequence induction (RSI) describes the preferred procedure to perform endotracheal placement of the tubus in emergency cases of patients with an increased risk of aspiration of gastric contents. For more than 50 years RSI has consisted of the application of suxamethonium for neuromuscular blockade because of its fast onset and ultra short duration. Due to the serious side effects of suxamethonium attempts were made to find better alternative neuromuscular blocking drugs, e.g. rocuronium, to perform RSI.In this small clinical series RSI was performed for general anesthesia of ten pregnant women for Caesarean sections using 1.0 mg/kgBW rocuronium for induction and maintaining deep relaxation until the end of surgery. For rapid reversal of the neuromuscular blockade to a train-of-four (TOF) ratio of 0.9, the µ-cyclodextrin sugammadex was administered at the end of surgery. Major and minor side effects, such as cardiac dysrhythmia, anaphylactic reactions, hoarseness and postoperative nausea and vomiting were documented.The combination of rocuronium and sugammadex for RSI combines rapid onset and rapid reversal of neuromuscular blockades with avoidance of serious side effects and very comfortable conditions for intubation in all cases. Minor side effects such as hoarseness, throat discomfort (in up to 30%) and myalgia (10%) for up to 48 h were documented.

Postoperative hypoxemia is a common complication in the anesthesia recovery room (ARR), which is predominantly based on the development of atelectasis, excessive intraoperative fluid shift and insufficient ventilation. The goal of this prospective observational study was to compare the effect of standard oxygen administration via a face mask with oxygen administration using the EzPAP® system, a device which additionally provides a positive end-expiratory pressure (PEEP).This study included 210 patients with postoperative hypoxemia (S(p)O(2) 93%) subdivided into the control group (105 patients) and the EzPAP group (105 patients). Postoperative residual paralysis was excluded using relaxometry and a train of four (TOF) ratio of 0.9 was assumed to ensure sufficient recovery of respiratory function from neuromuscular blockade. Patients who received a reversal of neuromuscular blockade were excluded. In cases of hypoxemia (S(p)O(2) 93%) control patients were treated with oxygen (6 l/min) using a face mask, whereas the EzPAP group received oxygen using the EzPAP® system. In order to adjust the PEEP in the EzPAP group, the O(2) flow was verified and measured by a manometer. After 1 h of oxygen therapy, the oxygen supply was stopped. In cases of reoccurring hypoxemia (S(p)O(2) 93%, persistence5 min), the oxygen therapy was restarted in both groups via a facemask. Both groups were compared using repeat measurement analysis of variance (ANOVA), the unpaired t-test, the Mann-Whitney U-test, Fisher's exact test and the χ(2)-test. The correlation of O(2) flow and PEEP was evaluated by regression analysis and p0.05 was considered to be statistically significant. Apart from this a subgroup analysis was performed depending on body-mass index (BMI), American Society of Anesthesiologists (ASA) classification, intraoperative airway management, the use of neuromuscular blocking agents and co-existing disorders, e.g. chronic obstructive lung disease (COLD), obesity and chronic heart failure.All patients were equally distributed between both groups with respect to demographic data, ASA classification, BMI, co-existing disorders and surgical procedures. The S(p)O(2) values did not differ between the EzPAP patients and the control group, except for 0.5 min after initiation of oxygen therapy: EzPAP group 96 ± 3.7% (mean ± standard deviation) versus the control group 93.8 ± 4.4% (p0.001). However, restarting oxygen therapy was less common in the EzPAP group (EzPAP group 25 versus control group 41, p = 0.03), as well as the occurrence of postoperative complications (EzPAP group 13 versus control group 25, p = 0.02), e.g. nosocomial pneumonia (0 versus 4) and wound infections (2 versus 3). Furthermore, patients with obesity and pulmonary disorders, such as COLD had a benefit from oxygen administration using the EzPAP device and showed higher postoperative than preoperative S(p)O(2) values. In contrast, the subgroup analysis of patients with heart failure did not reveal any differences between both groups and both groups did not differ in terms of time spent in the recovery room (EzPAP group 113 min versus control group 174.8 min, p = 0.2).In this observational study oxygen supply using the EzPAP® system appeared to be at least equally as effective in the therapy of postoperative hypoxemia compared to standard oxygen supply using a face mask. In patients with a high risk of postoperative hypoxemia, such as patients with obesity and/or pulmonary disorders, oxygen administration using the EzPAP® system possibly improves pulmonary oxygenation more effectively and is longer lasting compared to standard oxygen supply via a face mask. Hence, the EzPAP® system represents a well-tolerated, effective, cost-effective and easily operated tool to improve postoperative oxygenation. In order to investigate the possibilities of this promising tool more intensively, randomized clinical trials are warranted.

The management of general anaesthesia in patients with neuromuscular disorders remains challenging. The underlying causes and clinical presentations of these rare heterogeneous diseases are highly variable and the only common feature is usually skeletal muscle weakness. The appropriate choice and dosage of muscle relaxants are important and an adequate monitoring of the neuromuscular blockade is obligatory. Neuromuscular monitoring can be complicated because of disease-induced alterations in neurophysiology; however, continuous monitoring of the neuromuscular blockade should be realized to accurately determine the recovery from the blockade. These patients very often have an increased risk for postoperative pulmonary complications, which increases further if a residual neuromuscular blockade is present.

Neuromuscular blocking agents are used to facilitate intubation and to establish muscle paralysis during surgery. However, postoperative residual blocks are a significant complication following the use of neuromuscular blocking agents with an incidence of approximately 30 % at arrival in the post operative care unit. If they are not identified and adequately treated, residual neuromuscular blocks would increase the risk for muscle fatigue, hypoventilation, swallowing disorders, and aspiration. These complications may result in postoperative pulmonary disease. Therefore, monitoring of neuromuscular block is essential not only to detect residual paralysis postoperatively but also to maintain adequate muscle paralysis for surgery. Moreover, the response of individual patients to a particular drug can be variable and needs to be determined for the individual patient in a clinical situation. Sugammadex, the newly developed steroidal muscle relaxant encapsulator, is another important step to optimize treatment with neuromuscular blocking agents but will not replace neuromuscular monitoring. Since qualitative assessment has been shown to be insufficient to validly measure neuromuscular block in the anesthetized patient, it should be monitored quantitatively. Only using this technique and treating residual blocks where required, life threatening complications can certainly be avoided.

Neuromuscular blockade in ICU patients has become less popular, in particular since non-invasive methods of artificial respiration have been introduced. Succinylcholine has numerous side effects. Due to its short onset, Rocuronium may be an alternative. The advantage of Atracurium and Cis-Atracurium is a largely organ-independent metabolism. In ICU patients, neuromuscular monitoring should be applied. Prolonged action and critical illness neuropathy are the most prominent side effects of neuromuscular blockade.

The aim of the present study was to evaluate application customs of neuromuscular monitoring in hospitals and private practice. Of the 3,260 questionnaires sent out, 2,182 could be analyzed. Of these 54% were from anaesthetists in private practice, 41% from heads of hospital anaesthesia departments and 5% from heads of level 1 hospital anaesthesia departments. In 12.1% of the hospital departments and 66.7% of private practices, no neuromuscular monitoring was available at all. In both hospital departments and private practices, clinical signs were the most often applied criteria for timing of reinjection of myorelaxants as well as for evaluation of neuromuscular recovery.

Background: The ProSeal®-Laryngeal mask airway (PLMA) is increasingly used for surgical procedures that might require the intraoperative use of neuromuscular blocking agents. The airway seal of the PLMA depends on the interplay of the surrounding soft tissue of the neck and the cuff of the mask. An intraoperative neuromuscular blockade could lead to a decrease of the airway leak pressure (Pleak) secondary to the relaxation of the muscles of the neck. With this study we tested the hypothesis that a neu− romuscular blockade can result in a decreased Pleak of the PLMA. Methods: The Pleak of the PLMAwas studied in 73 female patients under total intravenous anaesthesia with propofol (0,1-0,15 mg/kg/min) and remifentanil (0,1-0,3 mg/kg/min) before and after a complete neuromuscular blockade produced by intra− venous injection of 0.6 mg/kg Rocuronium. Results: The Pleak decreased by more than 10% of the baseline Pleak in 8 out of 73 patients (11%); however, in the entire study population there was no significant difference between the mean baseline Pleak (28,5 +/- 7,3 cm H2O) and the mean Pleak after complete neuromus− cular blockade (29,1 +/- 7,0 cm H2O); (p = 0,128). Conclusion: No general correlation between application of a neuromuscular blocking agent and a decrease of the mean Pleak was found. How− ever, the decrease of the Pleak by more than 10% in 11% of the pa− tients shows that in certain patients the application of neuro− muscular blocking agents can result in a decreased Pleak of the PLMA and indicates the necessity to control the Pleak of the PLMA under complete muscle paralysis preoperatively when neuromuscular blocking agents are used., Hintergrund: Die ProSeal®−Kehlkopfmaske (PLMA) wird zuneh− mend für Eingriffe verwendet, bei denen eine intraoperative Gabe von Muskelrelaxantien notwendig sein kann. Der Atem− wegsverschluss der PLMA basiert auf ein Zusammenspiel zwi− schen den Halsweichteilen und dem Cuff der Maske. Eine intra− operative neuromuskuläre Blockade könnte durch Erschlaffung des umgebenden muskulären Widerlagers des Halses Einfluss auf den Leckagedruck (Pleak) der PLMA haben. Mit Hilfe der vor− liegenden Studie untersuchten wir die Hypothese, dass eine neu− romuskuläre Blockade zu einem Abfall des Pleak der PLMA führen kann. Material und Methoden: Der Pleak der PLMA wurden bei 73 Patientinnen unter totaler intravenöser Anästhesie mit Propofol (0,1-0,15 mg/kg/min) und Remifentanil (0,1-0,3 mg/kg/min) vor und nach kompletter neuromuskulärer Blockade durch Gabe von 0,6 mg/ Rocuronium gemessen. Ergebnisse: Bei 8 von 73 Patientinnen (11%) kam es zu einem Abfall des Pleak um mehr als 10% vom Ausgangs−Pleak. Im Gesamtpatientengut zeigte sich allerdings zwischen dem mittleren Ausgangs−Pleak (28,5 +/- 7,3 cm H2O) und dem mittleren Pleak unter kompletter neuromuskulärer Blockade (29,1 +/- 7,0 cmH2O) kein signifikanter Unterschied; (p = 0,128). Schlussfolgerung: Es fand sich kein ge− nerell nachweisbarer Abfall des mittleren Pleak der PLMA nach Gabe eines Muskelrelaxantiums. Der Abfall des Pleak um mehr als 10% bei 11% der Patientinnen ist ein Hinweis darauf, dass die Gabe von Muskelrelaxantien bei bestimmtem Patienten zu ei− nem Abfall des Pleak der PLMA führen kann und verdeutlicht die Notwendigkeit, bei der Verwendung von Muskelrelaxantien den Pleak möglichst präoperativ unter Vollrelaxierung zu bestimmen.

Fast-track rehabilitation refers to an interdisciplinary multimodal procedure to improve and accelerate recovery and avoid perioperative complications. The concept aims at reducing morbidity and discharging patients faster. It includes preoperative patient information, atraumatic surgical technique, stress reduction, pain therapy mostly via regional anesthetic techniques (frequently, thoracic epidural anesthesia), optimized fluid and temperature management, early enteral feeding, prophylaxis of gastrointestinal atony and postoperative nausea and vomiting, fast postoperative patient mobilization, and earlier hospital discharge. Fast-track protocols exist for all kind of surgical procedures but are best established for colon surgery.

Currently, the main aims of using neuromuscular blocking agents during general anaesthesia are the improvement of surgical and intubation conditions. Neuromuscular blocking agents themselves are neither analgesic nor anaesthetic. All agents interact with the acetylcholinergic receptor at the neuromuscular junction and induce a blockade either through a continuous activation imitating the effect of acetylcholine or through a competitive antagonism against acetylcholine. Succinylcholine is the only depolarizing muscle relaxant that is in clinical use. Non-depolarizing neuromuscular blockers may be grouped by their chemical structure into benzylisoquinolines or aminosteroids, and cover the complete range from short and intermediate, to long acting agents. Possible adverse drug reactions to the single agents are also related to their mechanism of action. Moreover, pharmacokinetic properties and effects such as histamine liberation could play an important role when choosing a myorelaxant. The depth of a neuromuscular block and recovery from paralysis can be monitored using qualitative and quantitative techniques. Therefore, the monitoring of neuromuscular recovery plays an important role in the prevention of postoperative complications due to residual paralysis. In case of residual paralysis, cholinesterase inhibitors are suitable for reversal.

The ProSeal laryngeal mask airway (PLMA) is increasingly used for surgical procedures that might require the intraoperative use of neuromuscular blocking agents. The airway seal of the PLMA depends on the interplay of the surrounding soft tissue of the neck and the cuff of the mask. An intraoperative neuromuscular blockade could lead to a decrease of the airway leak pressure (P (leak)) secondary to the relaxation of the muscles of the neck. With this study we tested the hypothesis that a neuromuscular blockade can result in a decreased P (leak) of the PLMA.The P (leak) of the PLMA was studied in 73 female patients under total intravenous anaesthesia with propofol (0.1 - 0.15 mg kg (-1) min (-1)) and remifentanil (0.1 - 0.3 microg kg (-1) min (-1)) before and after a complete neuromuscular blockade produced by intravenous injection of 0.6 mg kg (-1) Rocuronium.The P (leak) decreased by more than 10 % of the baseline P (leak) in 8 out of 73 patients (11 %); however, in the entire study population there was no significant difference between the mean baseline P (leak) (28.5 +/- 7.3 cm H(2)O) and the mean P (leak) after complete neuromuscular blockade (29.1 +/- 7.0 cm H(2)O); (p = 0.128).No general correlation between application of a neuromuscular blocking agent and a decrease of the mean P (leak) was found. However, the decrease of the P (leak) by more than 10 % in 11 % of the patients shows that in certain patients the application of neuromuscular blocking agents can result in a decreased P (leak) of the PLMA and indicates the necessity to control the P (leak) of the PLMA under complete muscle paralysis preoperatively when neuromuscular blocking agents are used.

Based on a computer simulation programme, the accuracy of the Graseby 3400 syringe pump was tested for its use in a feedback control system of the neuromuscular block. Firstly, a calculation of errors to determine the difference between the target and actual flow rates was carried out. Next, the characteristic curves of the syringe pump were determined under different flow and sampling rates to correct the application software of the feedback controller with a view to obtaining the correct flow rates online. It was discovered that, particularly with short 12 s sampling rates, dose-dependent errors of almost 100% were provable. Therefore, the application of a robust controller and integration of the characteristic curves at the outlet of the controller software are required. For the adoption of syringe pumps in medical feedback control systems, definite determination of the actual infusion quantity using an exact calculation of errors is required. Especially in cases of short sampling rates in combination with low infusion quantities, the syringe pump comes almost to a standstill, which results in extreme differences between target and actual flow rates.

Under clinical conditions constant neuromuscular blockade can also be maintained by a simple closed-loop system. However, delayed onset time, non-linearity of the dose-response curve and different sensitivity to muscle relaxants for each patient are limiting factors.In 20 patients who underwent elective surgical procedures under continuous propofol/alfentanil anaesthesia and relaxation with cisatracurium, the maintenance of an electromyographically controlled cisatracurium block of 90% was achieved by a varying on-off control system. Using an own computer-aided measuring device, the course of the neuromuscular blockade and deviations from the desired neuromuscular block were registered.Over a period of 64.2+/-14.0 min, neuromuscular block could be controlled on average at a T(1)-level of 10% (90% block). The mean error of the deviation of the obtained neuromuscular blockade from the set-point was -1.6+/-0.9% on average. To maintain this neuromuscular blockade, a dose rate of 1.4+/-0.9 micro g x kg(-1) x min(-1) cisatracurium was necessary.It can be concluded that a simple closed-loop system allows the safe use of the intermediate term muscle relaxant cisatracurium for the performance of surgical procedures.

In adults, sevoflurane augments the intensity of rocuronium evoked neuromuscular blockade. However, in children effective doses and onset of action of rocuronium have not been reported during sevoflurane anaesthesia. To test in children the hypothesis that sevoflurane speeds the onset and potentiates the degree of rocuronium induced neuromuscular blockade we studied 50 children aged 2 - 7 years following approval by the local ethics committee.After induction and maintenance of anaesthesia with either 2 % endtidal sevoflurane in 60 % N(2)O/O(2) (n = 30) or with propofol (3 mg small middle dot kg(-1) and 10 mg small middle dot kg(-1)h(-1), n = 20) and 60 % N(2)O/O(2) for 17 +/- 1 min, we injected either 0.15, 0.22, or 0.3 mg small middle dot kg(-1) rocuronium and quantified by mechanomyography the evoked (0.1 Hz ulnar nerve stimulation) response of the adductor pollicis muscle. Dose-response relationships of rocuronium under both anaesthetic regimes were assessed using a generalised linear model based on the maximum-likelihood-technique. Data were compared by analysis of covariance, F-test, and Mann-Whitney-U-test as indicated, p0.05, mean +/- SD, (95% confidence interval).The degree of neuromuscular blockade was greater (p0.05) during sevoflurane (estimated ED 50: 0.15 (0.076 - 0.177) mg small middle dot kg(-1)) than propofol (ED 50: 0.25 (0.15 - 0.35) mg small middle dot kg(-1)) anaesthesia. Furthermore, onset time was significantly faster under sevoflurane/N(2)O compared to propofol/N(2)O anaesthesia (110 +/- 31 versus 230 +/- 52 s, p0.01, after rocuronium 0.3mg small middle dot kg(-1)).In young children during steady state anaesthesia onset of action of rocuronium is halved and the degree of neuromuscular blockade is markedly augmented during sevoflurane/N(2)O anaesthesia compared to propofol.

Myasthenia gravis is a chronic autoimmune disease characterised by progressive weakness and easy fatigability of voluntary skeletal muscles. These symptoms are related to a decrease in the number of functional acetylcholine receptors, impaired neuromuscular transmission, and a broadened neuromuscular cleft. Symptomatic treatment is based on anticholinesterases in order to increase the synaptic dwell of acetylcholine. Immune therapy includes immune suppressive drugs, plasma exchange, immunoglobulins, and thymectomy. Anticholinesterase therapy should be continued in the current mode until anaesthesia. Regional anaesthesia should be preferred. Although sensitivity to non-depolarising neuromuscular blocking agents is increased, muscle relaxants can be administered during general anaesthesia as long as neuromuscular monitoring assesses their individual effect. Due to the individual variability in the response to muscle relaxants, accurate titration in combination with pre- and intraoperative neuromuscular monitoring is essential for myasthenic patients. Postoperatively, intensive care observation is mandatory including neuromuscular monitoring.

In the present study 48 sagittal and transversal magnetic resonance images of volunteers were examined for biometric data concerning risk of pneumothorax at the vertical infraclavicular blockade (VIP) of the brachial plexus. With a correct puncture the plexus can be reached after 3 cm. The shortest way to the lung is 5.3 cm (3.1-8.7 cm) at a incorrect medial angle of puncture of 46.3 degrees (35-58 degrees). While moving the angle of puncture at a minimum of 24.1 degrees (1-51 degrees) in a medial direction, a depth of 6.1 cm (4-8.9 cm) has to be reached for fatal lung puncture. The puncture point has to be determined 2.8 cm (0-4.1 cm) towards the midline of the body to have a pleura connection by a strictly vertical puncture at 6 cm (4-8.9 cm). In asthenic women, shorter distances were obtained. A considerable lower deviation can lead to pleural damage (7.5 degrees; 4.7 cm). The plexus is very close to the skin surface (1.6-3 cm). In one case, the risk for pneumothorax could be measured even with the correct puncture technique. Overall, the VIP is a very safe method for brachial plexus anaesthesia with regard to the risk of pneumothorax. In asthenic women, the risk seems to be higher but can be minimised by reducing the maximum puncture depth.