Tino Muenster

Onset and duration of rocuronium-induced neuromuscular blockade in patients with Duchenne muscular dystrophy.

Background: In patients with Duchenne muscular dystrophy (DMD) the response to nondepolarizing muscle relaxants is scarcely documented and conflicting. The current study was conducted to determine the time to peak effect and the time for complete spontaneous recovery after a single dose of 0.6 mg/kg of rocuronium in patients with DMD. Methods: Twenty-four patients (12 with DMD, 12 controls, aged 10–16 yr) were studied. All patients were anesthetized with propofol and fentanyl/remifentanil. Neuromuscular transmission was monitored by acceleromyography. After induction all patients received a single dose of 0.6 mg/kg of rocuronium. The complete time course of onset and spontaneous recovery were recorded Results: Significant (P < 0.01) increase in the onset times to 95% neuromuscular block was observed in DMD patients (median, 203 s; range, 90–420 s) compared with controls (median, 90 s; range, 60–195 s). The time between rocuronium administration and recovery of first twitch of the train-of-four to 90% was significantly (P < 0.01) prolonged in DMD compared with controls (median, 132 min; range, 61–209 min versus 39 min; 22–55 min). The recovery index was also significantly prolonged in the DMD group compared with controls (median, 28 min, range, 15–70 min versus 8 min; 3–14 min). Conclusions: The most striking and surprising result of this study is the delayed onset of blockade in DMD after a standard dose of rocuronium. This effect should be kept in mind in situations when a rapid airway protection is necessary in DMD patients. The documented very long recovery from rocuronium-induced block emphasizes the need for careful assessment of neuromuscular function in DMD patients.

Rocuronium 0.3 mg·kg−1 (ED95) induces a normal peak effect but an altered time course of neuromuscular block in patients with Duchenne's muscular dystrophy

Background:  In patients with Duchennes muscular dystrophy (DMD) recovery from neuromuscular block is delayed. It has been assumed that this is because of a higher potency of muscle relaxants in this patient cohort. We determined the peak effect, and the time course of action of rocuronium 0.3 mg·kg−1 (ED95) in DMD patients.

Anaesthetic management in patients with Duchenne muscular dystrophy undergoing orthopaedic surgery: a review of 232 cases.

Context Patients with Duchenne muscular dystrophy are at increased risk of some anaesthesia-related hazards such as rhabdomyolysis, fever and hyperkalaemia. Objectives To evaluate the management of anaesthesia in patients with Duchenne muscular dystrophy, including preoperative evaluation, intraoperative performance, critical events and postoperative care. Design We performed a retrospective case review study of anaesthesia in patients with Duchenne muscular dystrophy covering the period between April 2000 and December 2008. Patients 91 Duchenne patients undergoing 232 general anaesthetics for orthopaedic surgical interventions. Setting University hospital. Results Anaesthesia was performed using propofol, opioids and, if required, a non-depolarising muscle relaxant. Eight difficult direct laryngoscopies were reported. All patients undergoing spinal fusion surgery received transfusion of homologous blood products and required postoperative invasive ventilatory support for an average of 19 h. There was no severe anaesthesia-related complication and no case of unexplained fever or rhabdomyolysis. Conclusion This retrospective survey confirms clinical experience that total intravenous anaesthesia can be used safely in Duchenne patients without major concern. Further prospective studies are necessary to establish evidence-based clinical guidelines for daily practice.

A priming technique accelerates onset of neuromuscular blockade at the laryngeal adductor muscles

PurposePriming is a known technique to accelerate onset of neuromuscular blockade (NMB). Its effect on NMB of the larynx has not been studied yet.MethodsWe compared a priming technique with a bolus application of rocuronium on the onset of NMB at the laryngeal adductor and the adductor pollicis muscles (AP). In 30 female patients, after induction of anesthesia a tube with a surface electrode was placed into the trachea prior to the administration of any neuromuscular blocking agent to monitor electromyography (EMG) of the laryngeal adductor muscles. Neuromuscular monitoring consisted of EMG of the laryngeal adductor muscles and the left AR Patients were randomized into two groups. After transcutaneous stimulation of the recurrent laryngeal nerve and ulnar nerve, a bolus of rocuronium 0.6 mg·kg−1 (Bolus group) or a priming dose of rocuronium 0.06 mg·kg−1 followed by rocuronium 0.54 mg·kg−1 three minutes later (Priming group) were injected. Lag time, onset 90%, onset time and peak effect of NMB were recorded and compared; aP < 0.05 was considered significant.ResultsThe onset 90% and onset time measured at the laryngeal adductor muscles (onset: 44.7 ± 7.4vs 74.0 ± 23.8 sec) and at the AP (onset: 105.4 ± 29.9vs 139.2 ±51.5 sec) were significantly shorter in the Priming group than in the Bolus group. Within groups, the onset times were significantly shorter at the laryngeal muscles in comparison to ARConclusionOur results indicate that a priming technique with rocuronium significantly accelerates the onset of NMB at the laryngeal adductor muscles. Our results further support the use of rocuronium as an alternative to succinylcholine for rapid sequence induction.RésuméObjectifLamorçage est une technique connue pour accélérer l’installation du blocage neuromusculaire (BNM). Son effet sur le BNM du larynx n’a pas encore été étudié.MéthodeNous avons comparé une technique d’amorçage et l’injection de bolus de rocuronium au début du BNM de l’adducteur du larynx et de l’adducteur du pouce (AP). Après l’induction de l’anesthésie chez 30 patientes, un tube muni d’une électrode superficielle a été placé dans la trachée avant l’administration d’agent myorelaxant pour permettre le monitorage électromyographique (EMG) des muscles adducteurs du larynx. Le monitorage de la transmission neuromusculaire consistait à l’EMG des muscles adducteurs du larynx et de l’AP gauche. Les patientes ont été réparties aléatoirement en deux groupes. Après la stimulation transcutanée du nerf laryngé récurrent et des nerfs cubitals, un bolus de rocuronium de 0,6 mg·kg−1 (groupe Bolus) ou une dose d’amorçage de 0,06 mg·kg−1 de rocuronium suivis de 0,54 mg·kg−1 de rocuronium trois minutes plus tard (groupe Amorçage) ont été injectés. La période latence, le moment où le bloc est installé à 90 %, le délai d’installation et le moment de l’effet maximal du BNM ont été notés et comparés; un P < 0,05 était considéré significatif.RésultatsLe bloc neuromusculaire à 90 % et le délai d’installation mesurés aux adducteurs du larynx (début: 44,7 ± 7,4 vs 74,0 ± 23,8 sec) et à l’AP (début: 105,4 ± 29,9 vs 139,2 ± 51,5 sec) ont été signifcativement plus courts dans le groupe Amorçage que dans le groupe Bolus. A l’intérieur des groupes, les délais d’installation du bloc ont été significativement plus courts aux muscles laryngés qu’à l’AP.ConclusionUne technique d’amorçage avec du rocuronium accélère de façon significative l’installation du BNM aux muscles adducteurs du larynx. De plus, nos résultats sont en faveur de l’usage de rocuronium pour remplacer la succinylcholine dans l’induction en séquence rapide.

Influence of disease progression on the neuromuscular blocking effect of mivacurium in children and adolescents with Duchenne muscular dystrophy.

Background:Studies with nondepolarizing neuromuscular blocking agents showed a delayed onset and prolonged recovery in patients with Duchenne muscular dystrophy. The objective of this study was to investigate if these alterations depend on disease progression. Methods:The authors studied 11 children (6–9 yr) with moderate Duchenne muscular dystrophy, 11 adolescents (12–16 yr) with advanced Duchenne muscular dystrophy, and 2 age-matched control groups of 8 patients each (5–9 and 10–17 yr). Anesthesia was performed with propofol and remifentanil. Patients received a single intravenous dose of 0.2 mg/kg mivacurium. Neuromuscular transmission was monitored by acceleromyography. The time course of neuromuscular blockade was characterized by the onset time and the times to different levels of recovery. Results:Onset and duration of neuromuscular blockade were significantly prolonged in adolescent Duchenne muscular dystrophy patients (onset time, 4.0 min; recovery index, 12.3 min; median), as compared with Duchenne muscular dystrophy children (onset time, 2.3 min; recovery index, 6.8 min), and also as compared with young controls (onset time, 2.0 min; recovery index, 4.4 min) and adolescent controls (onset time, 2.5 min; recovery index, 4.8 min). Within the Duchenne muscular dystrophy patients, onset time and recovery index increased significantly with age. In the control group, age had no effect. Conclusions:The neuromuscular blocking effects of mivacurium showed a significant age dependency in Duchenne muscular dystrophy patients, which was most probably caused by the progression of the disease.

Reversal of rocuronium‐induced neuromuscular blockade by pyridostigmine in patients with Duchenne muscular dystrophy

Background:  The aim of this study was to investigate the effect and safety of pyridostigmine for the reversal of a neuromuscular block (NMB) in patients with Duchenne muscular dystrophy (DMD). In patients with DMD recovery from a rocuronium‐induced NMB is markedly delayed.

Dystrophin deficiency, inhalational anesthetics, and rhabdomyolysis

SIR–I read with interest the report of a suspected case of malignant hyperthermia in a child with laminin alpha 2 (merosin) deficiency in the absence of a triggering agent (1). I have two concerns about the report. First I believe that the authors did not substantially support their diagnosis of malignant hyperthermia. Their scoring of the episode is on the high side (2), nor is their explanation for the lack of a very elevated CPK very strong, since despite the use of dantrolene, CPK continued to rise in the postoperative period. As their patient exhibited a primary muscle response, did the authors look for myoglobinuria? My second concern is the linking of the disease laminin alpha 2 (merosin) deficiency to malignant hyperthermia. This is a common mistake to causally link two very rare diseases just because they happened simultaneously. As this particular child had previous general anesthetics with no evidence of malignant hyperthermia, it is not reasonable to label all children with this disease susceptible to MH. James Mayhew Texas Tech Health Science Center, Anesthesiology, Lubbock, Texas, USA (email: rejfm@hotmail.com)