Use of non-invasive-stimulated muscle force assessment in long-term critically ill patients: a future standard in the intensive care unit?

BACKGROUND: This study's main purpose was to test the feasibility of employing a non-invasive-stimulated muscle force assessment approach in long-term critically ill patients. METHODS: A case series was performed over a 4-year period in the intensive care unit (ICU). Of the 25 patients initially recruited, eight patients required long-time mechanical ventilation for a median of 3.8 weeks (range 2-10 weeks) and were immobilized for 5 weeks (range 2-10 weeks). With a previously tested non-invasive measuring device, we weekly assessed peak torques and rates of force development and relaxation of patients' ankle dorsiflexor contractile responses, induced via peroneal nerve stimulation. Subsequently, we derived each patient's time course of observed progressive weakness and/or recovery. RESULTS: During their critical illnesses, seven out of eight patients elicited significant decreases in measured peak torques. In survivors (n = 6) during their recovery periods, torques gradually recovered. In the two patients who died, their strengths decreased continuously until death. The rate of force development data elicited similar trends as peak torque responses, whereas relative relaxation rates differed more widely between individuals. CONCLUSION: This approach of non-invasive-stimulated muscle force assessment can be used in long-term critically ill patients and may eventually become a standard in the intensive care unit, e.g. for assessing recovery. This method is easy to employ, reproducible, provides important phenotypic quantification of skeletal muscle contractile function, and can be used for long-term outcomes assessment.

Similar susceptibility to halothane, caffeine and ryanodine in vitro reflects pharmacogenetic variability of malignant hyperthermia.

BACKGROUND AND OBJECTIVE: To analyse the use of standardized application of ryanodine for in vitro muscle contracture testing to define cut-off values separating malignant hyperthermia susceptible from malignant hyperthermia negative subjects. Furthermore, we compared the results of in vitro muscle-contracture tests following the halothane, caffeine and ryanodine challenges. METHODS: In 113 subjects, halothane, caffeine and ryanodine muscle-contracture tests were performed according to the protocol of the European Malignant Hyperthermia Group. RESULTS: Malignant hyperthermia susceptible subjects (n = 77) had significantly shorter onset times in the ryanodine in vitro muscle-contracture test (1 micromol ryanodine) compared with malignant hyperthermia negative subjects (n = 36), median 4.8 vs. 20.1 min, respectively, without any influence of age or gender. The best cut-off value was 10 min (sensitivity 0.78 and specificity 0.94, respectively). Shorter cut-off values had greater specificity, but lower sensitivity. Groups could not be separated without an overlap. In susceptible subjects, we found a correlation between onset time and threshold concentrations for halothane and caffeine (p = 0.47 and 0.52, respectively). In addition, muscle bundles with high susceptibility to halothane and caffeine also showed high susceptibility to ryanodine. CONCLUSIONS: The ryanodine in vitro muscle-contracture test confirmed the malignant hyperthermia status that was determined using the halothane and caffeine in vitro muscle-contracture tests. Due to an overlap between the two groups, discrimination ability was not always perfect and short cut-off values with higher specificity had reduced sensitivity and vice versa. The correlation of contractures following the halothane, caffeine and ryanodine challenges points towards a similar individual pharmacogenetic effect rather than a specific, different pharmacological action between the three agents.

Effect of three anaesthetic techniques on isometric skeletal muscle strength.

BACKGROUND: Our aim was to quantify human involuntary isometric skeletal muscle strength during anaesthesia with propofol, sevoflurane, or spinal anaesthesia using bupivacaine. METHODS: Thirty-three healthy patients undergoing anaesthesia for elective lower limb surgery were investigated. Twenty-two patients received a general anaesthetic with either propofol (n=12) or sevoflurane (n=10); for the remaining 11 patients spinal anaesthesia with bupivacaine was used. We used a non-invasive muscle force assessment system before and during anaesthesia to determine the contractile properties of the ankle dorsiflexor muscles after peroneal nerve stimulation (single, double, triple, and quadruple stimulation). We measured peak torques; contraction times; peak rates of torque development and decay; times to peak torque development and decay; half-relaxation times; torque latencies. RESULTS: Males elicited greater peak torques than females, medians 6.3 vs 4.4 Nm, respectively (P=0.0002, Mann-Whitney rank-sum test). During sevoflurane and propofol anaesthesia, muscle strength did not differ from pre-anaesthetic values. During spinal anaesthesia, torques were diminished for single-pulse stimulation from 3.5 to 2.0 Nm (P=0.002, Wilcoxon signed rank test), and for double-pulse from 7.6 to 5.6 Nm (P=0.02). Peak rates of torque development decreased for single-pulse stimulation from 113 to 53 Nm s(-1) and for double pulse from 195 to 105 Nm s(-1). Torque latencies were increased during spinal anaesthesia. CONCLUSIONS: At clinically relevant concentrations, propofol and sevoflurane did not influence involuntary isometric skeletal muscle strength in adults, whereas spinal anaesthesia reduced strength by about 20%. Muscle strength assessment using a device such as described here provided reliable results and should be considered for use in other scientific investigations to identify potential effects of anaesthetic agents.

[The hereditary motor-sensory neuropathy Charcot-Marie-Tooth disease: anesthesiologic management--case report with literature review]. / Die hereditäre motorischsensible Neuropathie: Charcot-Marie-Tooth-Erkrankung. Anästhesiologisches Management--ein Fallbericht und eine Literaturübersicht.

A 53-year-old woman diagnosed as having hereditary motor-sensory neuropathy Charcot-Marie-Tooth (CMT) disease Type 2, underwent inguinal hernia surgery. In this patient CMT disease was manifested as distal muscle weakness and wasting. Anaesthetic experience with patients who have CMT disease is limited. Association to malignant hyperthermia is very unlikely although there is one case report that shows that there could be a relationship. We describe a total intravenous anaesthesia (TIVA) protocol with propofol and alfentanil without any muscle relaxants after fiberoptic intubation. The patient made an uneventful recovery and was discharged from the hospital on the fourth postoperative day. TIVA was a safe technique in this patient and should be considered as an alternative for patients presenting with CMT disease.

Abdominal haemorrhage--a preventable cause of death after field stabilization?

The causes of preventable death vary in different operational settings, and the topic has not previously been explored in a fully developed central European rescue system. The factors associated with potentially preventable death were studied in a retrospective study of 430 fatal traffic accident victims (1980-96) in Lörrach County, Germany. Mission protocols could be retrieved for detailed analysis in 239 of the cases. These were studied in order to identify factors associated with preventable death. At the scene of the accident, 38% of the patients died without cardiopulmonary resuscitation (CPR) and 18% after CPR. Four patients died after a certain delay without CPR before reaching hospital. A total of 43% of the victims were admitted to hospital, 5% had received prehospital CPR and the remaining 38% had not. In a subgroup representing the experience of a single emergency physician 60 fatalities were studied. Of these, 27 (45%) patients died within the hospital; almost half of these cases (13/27) had been conscious at some time after the accident and of these, seven (7/13) died from intra-abdominal bleeding within 4 h after admission. The same cause of death was found in 3 of the 14 comatose patients. Pleural drainage was carried out in four patients and unrecognized pneumothoraces or spinal injuries did not occur. Tracheal intubation was employed in 24/27. Medical antishock trousers (MAST) were not available. The data indicate that intra-abdominal haemorrhage is an underestimated cause of death in a comprehensive rescue system, possibly as a consequence of field stabilization. The use of MAST may be a relevant therapeutic option to prevent these fatalities. The method offers the possibility of intra-abdominal compression and haemostasis after tracheal intubation has been performed. Previous controlled studies on MAST may have been biased by faulty methodology (e.g. absence of tracheal intubation) and inappropriate indications (e.g. other causes of shock). The value of MAST in comprehensive rescue systems should therefore be reassessed. The difficulties in identifying factors leading to preventable death in a retrospective analysis, are discussed and it is recommended that a permanent prospective quality control be performed in all cases of fatal accidents in order to ensure the continued improvement of prehospital emergency medical systems.

[Excessive tissue storage of colloids in the reticuloendothelial system]. / Exzessive Gewebespeicherung von Kolloiden im retikuloendothelialen System.

In addition to renal elimination and gastrointestinal metabolism (amylase; splenic and hepatic dextranase) colloid plasma solutions like dextran and hydroxyethyl starch deposit in tissues, especially in the reticuloendothelial system (RES). This tissue storage is limited in time (weeks to months), is influenced by the employed solution and other factors (lysosomes) and has usually no clinical importance (no RES blockade). We report here a case study of a patient with sepsis (lung, liver and kidney failure) who had an overload of the RES with colloids while being treated with dextran (molecular weight 40,000 and 70,000 daltons) and hydroxyethyl starch (mw 450,000 daltons, molar substitution 0,7) for 5 weeks. Autopsy showed parenchymal and reticuloendothelial cells of liver, lung, kidney and spleen with a large amount of colloid mass inclusions and altered organ morphology. This storage may have impaired ventilation, transport of bile acids and renal function. A possible role of tissue storage of colloids in organ failure is discussed.

[Neuromuscular blockade after atracurium and alcuronium with propofol and thiopental]. / Neuromuskuläre Blockade nach Atracurium und Alcuronium unter dem Einfluss von Propofol und Thiopental.

UNLABELLED: Does propofol or thiopentone enhance the effect of nondepolarizing muscle relaxants? We evaluated the effects of propofol and thiopentone on the pharmacodynamics of atracurium and alcuronium in 43 surgical patients (ASA I and II) under general anaesthesia. METHODS: The patients were randomized into five groups, A-E. Anaesthesia was induced in all patients with fentanyl 4 micrograms/kg i.v. Patients in groups A and C patients received thiopentone 7 mg/kg i.v., and relaxation was achieved with alcuronium 0.25 mg/kg (group A) and atracurium 0.5 mg/kg (group C). Electromyography (train of four, TOF) was used to determine the time of onset of relaxation (AZ) and the maximum degree of blockade (T%). The recovery times to 25%, 50% and 75% of baseline muscle strength were recorded. Additionally, the TOF ratio T4:T1 was calculated, indicating the probable end of relaxation at a ratio of 0.7. At the beginning of the recovery phase (T1 = 15%) propofol 1% 3 mg/kg was given, and the effect on the TOF was measured. Patients in groups B and D patients received total intravenous anaesthesia (TIVA) with propofol 1% 6-12 mg/kg per hour continuously after induction with 3 mg/kg. The action profile of alcuronium 0.25 mg/kg (group B) and atracurium 0.5 mg/kg (group D) were recorded. Group E patients received thiopentone (10 mg/kg per hour) under the use of atracurium 0.5 mg/kg. Ventilation was performed with 30%/70% oxygen and N2O. The results were analyzed for significance using the Mann-Whitney U-test (P = 0.019). RESULTS: A slight difference in AZ was noted for alcuronium under the use of TIVA between propofol and thiopentone: 13 min and 5 min, respectively. Otherwise, the pharmacodynamics (T% and recovery of neuromuscular function) of the two relaxants exhibited no major differences related to thiopentone, propofol or their combination. The TOF was not influenced under additional propofol application. Noteworthy were the wide distribution of the time course of action (up to 3 h) and the magnitude of T% depression under alcuronium. CONCLUSION: Propofol and thiopentone have no potentiating influence on the time course of action and the magnitude of relaxation with alcuronium and atracurium. Pharmacodynamics of nondepolarizing muscle relaxants do not seem to be influenced by these two hypnotics.