[Algorithm-based preventive strategies for avoidance of residual neuromuscular blocks]. / Algorithmusbasierte Präventionsstrategien zur Vermeidung neuromuskulärer Restblockaden.

BACKGROUND: Postoperative residual neuromuscular block (train of four ratio <0.9) 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? METHODS: A selective literature search was carried out in PubMed and guidelines of national specialist societies were searched using special terms. RESULTS: 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. CONCLUSION: 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.

[Deep neuromuscular blockade : Benefits and risks]. / Vollrelaxation : Nutzen und Risiken.

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.

Effects of single-shot and steady-state propofol anaesthesia on rocuronium dose-response relationship: a randomised trial.

BACKGROUND: Similar to volatile anaesthetics, propofol may influence neuromuscular transmission. We hypothesised that the administration of propofol influenced the potency of rocuronium depending on the duration of the administration. METHODS: After consent, patients scheduled for elective surgery randomly received rocuronium either after induction of anaesthesia with propofol (2 min of propofol, n = 36) or after 30 min of propofol infusion (30 min of propofol, n = 36). Remifentanil was given in both groups. Neuromuscular monitoring was performed by calibrated electromyography. The dose-response relationship of rocuronium was determined with a single-bolus technique (0.07, 0.1, 0.15, 0.2, 0.3 and 0.45 mg/kg rocuronium). The primary endpoints were the ED50 and ED95 of rocuronium after 2 and 30 min propofol. Data are presented as means with (95% confidence interval). The trial is registered with the Eudra-CT: 2009-012815-16. RESULTS: A total of 72 patients were included. Time to maximal neuromuscular blockade was significantly shorter in patients after 30 min of propofol [3.3 min (2.9-3.7)] compared with patients anaesthetised with 2 min of propofol [4.6 min (4.0-5.2)]. After 30 min of propofol, the slope of the dose-response curve was significantly steeper (30 min of propofol: 4.34 [3.62-5.05]; 2 min of propofol: [3.34 (2.72-3.96)], resulting in lower ED95 values of rocuronium (30 min of propofol: 0.287 mg/kg [0.221-0.368]; 2 min of propofol [0.391 mg/kg (0.296-0.520)]. The ED50 were not different between groups. CONCLUSION: The potency of rocuronium was significantly enhanced after propofol infusion for 30 min. Estimates of potency those are usually determined during steady-state anaesthesia might underestimate rocuronium requirements for endotracheal intubation at the time of induction.

Magnesium-induced recurarisation after reversal of rocuronium-induced neuromuscular block with sugammadex.

A 61-year-old woman (57 kg, 171 cm) underwent surgery under general anaesthesia with desflurane 5.8-6.1 vol. % end-tidal, remifentanil 0.2-0.4 µg/kg/min and rocuronium 35 mg (0.61 mg/kg). On return of the second twitch in the train-of-four (TOF) stimulation measured by acceleromyography, sugammadex 120 mg (2.1 mg/kg) was given. After complete neuromuscular recovery, magnesium sulphate 3600 mg (60 mg/kg) was injected intravenously over 5 min to treat atrial fibrillation. This was associated with recurarisation with a nadir [first twitch=25%, TOF ratio (TOFR)=67%] 7 min after the start of the magnesium sulphate infusion (magnesium plasma level: 2.67 mM). A spontaneous twitch value and a TOFR of >90% were observed 45 min after the beginning of the magnesium sulphate infusion under general anaesthesia. Rapid infusion of magnesium sulphate may re-establish a sugammadex-reversed, rocuronium-induced neuromuscular block during general anaesthesia, probably because of the high plasma level of magnesium (2.67 mM). Desflurane and a small fraction of unbound rocuronium may amplify the known muscle relaxing effects of magnesium. Intravenous injection of magnesium sulphate is not recommended in patients after general anaesthesia with neuromuscular relaxants, particularly after sugammadex reversal. Quantitative neuromuscular monitoring should be used for reversing aminosteroid muscle relaxants with sugammadex--particularly in combination with magnesium injection--to prevent post-operative residual curarisation.

The use of sugammadex in a patient with myasthenia gravis.

Myasthenia gravis, affecting neuromuscular transmission, leads to a large variability in sensitivity to depolarising and non-depolarising neuromuscular blocking drugs. We report the successful use of the modified mu-cyclodextrin sugammadex in a myasthenic patient to reverse a rocuronium-induced deep level of neuromuscular block. After spontaneous neuromuscular recovery of T2 (second twitch of the train-of-four series), we administered 2 mg.kg(-1) of sugammadex intravenously, reversing neuromuscular blockade to a train-of-four ratio (T4/T1) > 90% within 210 s. Sugammadex, in combination with objective neuromuscular monitoring, can be used to reverse rocuronium-induced neuromuscular blockade in patients with myasthenia gravis, thereby avoiding the need for reversal with acetylcholinesterase inhibitors.

[Postoperative acute mitral regurgitation. Unexpected finding after minor non-cardiac surgery]. / Akute perioperative Mitralklappeninsuffizienz. Unerwarteter Befund nach nichtkardiochirurgischem Bagatelleingriff.

This report describes the case of a 59-year-old man who was scheduled for general anesthesia with propofol, sufentanil and sevoflurane for removal of a metal implant. The patient was classified as American Society of Anesthesiologists (ASA) II status because of an asymptomatic mitral valve prolapse and medically treated arterial hypertension. During induction of narcosis a pulsoxymetrically measured inadequate increase in oxygen saturation after preoxygenation was noticed and a moderate respiratory obstruction occurred intraoperatively, but anesthesia was uneventfully completed and the patient was extubated. However, 3 h later the patient developed severe dyspnea, hypoxia, tachycardia and arterial hypotension. Physical examination revealed a new grade 4/6 systolic murmur radiating to the axilla and X-ray showed bilateral pulmonary edema. Neither electrocardiographic nor biochemical manifestations of acute myocardial infarction were identified but transthoracic echocardiography revealed fluttering of the posterior leaflet of the mitral valve with grade III regurgitation and dilation of the left atrium. Coronary angiography was normal and left ventriculography confirmed severe mitral regurgitation. Mitral valve repair was successfully performed 22 h after presentation of symptoms. Mitral regurgitation is a common finding on echocardiography, seen to some degree in over 75% of the population. The etiology of mitral valve insufficiency which can be caused by pathologic changes of one or more of the components of the mitral valve, including the leaflets, annulus, chordae tendineae, papillary muscles, or by abnormalities of the surrounding left ventricle and/or atrium are discussed. Rupture of mitral chordae tendineae is infrequent and causes acute hemodynamic deterioration and needs corrective surgery. Valve replacement should be performed only if mitral valve repair is not possible. Echocardiography is an invaluable tool in determining the severity of regurgitation, the integrity of the mitral valve apparatus, the extent of left ventricular enlargement, and the ejection fraction. Acute mitral valve regurgitation caused by a rupture of chordae tendineae should be considered in the differential diagnosis of perioperative acute pulmonary edema.