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Twitch Height (twitch + height)
Selected AbstractsAttenuation of a rocuronium-induced neuromuscular block in patients receiving prednisoloneACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2009S. SOLTÉSZ Background: This study tested the influence of continuous medication (more than 4 weeks) with prednisolone on a rocuronium-induced neuromuscular block. Methods: The time course of a rocuronium-induced neuromuscular blockade (0.3 mg/kg) was investigated in 40 patients with chronic inflammatory bowel disease undergoing elective abdominal surgery. The primary end point was the time from the start of injection of rocuronium until recovery of the TOF ratio to 0.9. Twenty patients received continuous medication with prednisolone (group A), and 20 were without glucocorticoid medication (group B). Additionally, another 20 patients without inflammatory bowel disease and without glucocorticoid medication served as control (group C). Results: The onset time was prolonged in group A [253 (51.2) s] compared with group B [187 (61.3) s]. Twitch height at the onset of the block was higher in group A [16.5 (0,61)%] than that in group B [5.0 (0,33)%]. The duration to 25% twitch height was shorter in group A [12.6 (0,20.7) min] compared with group B [16.7 (0,25.3) min] and group C [16.9 (0,29.3) min]. The recovery to a train-of-four ratio of 0.9 was reduced in group A [25.7 (23,34.3) min] compared with group B [34.7 (32.7,44.2) min] and group C [36.5 (31.7,42.3) min]. Conclusions: Prednisolone treatment in patients with inflammatory bowel disease is associated with a delayed onset and a shorter duration of action of rocuronium. The presence of an inflammatory bowel disease did not influence the neuromuscular block. [source] Characterisation of the effects of potassium channel modulating agents on mouse intestinal smooth muscleJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 3 2002Chi-Kong Yeung The actions of agents which modulate ATP-sensitive potassium (KATP) channels in excitable cells were investigated in an in-vitro preparation of mouse ileum from which the mucosa was removed. A range of potassium channel openers of diverse structure, cromakalim (0.1,100 ,M), pinacidil (0.1,200 ,M) and its analogue P1060 (0.1,200 ,M), SDZ PCO400 ((-)-(3S,4R)-3,4-dihydro-3-hydroxy-2,2-dimethyl-4-(3-oxo-cyclopent-1-enyloxy)-2H -1-benzopyran-6-carbonitrile) (0.3,60 ,M), caused concentration-related reduction in twitch height of electrical field stimulated ileum. P1060 and SDZ PCO400 were the most potent agents; diazoxide (0.1,100 ,M) was without effect. The order of inhibitory potency, based on EC50 values (concentration of a relaxant producing 50% of the maximum inhibition of twitch) was: P1060 = SDZ PCO400 > cromakalim > pinacidil. The relaxant effect of the potassium channel openers was antagonised by the sulfonylureas glibenclamide (0.1-1.0 ,M) and glipizide (3,30 ,M) but the nature of the antagonism differed. Antagonism of P1060 and SDZ PCO400 by glibenclamide appeared to be competitive whereas the antagonism of relaxation induced by cromakalim and pinacidil was apparently not competitive. Both phentolamine (1,10 ,M) and tolbutamide (100,300 ,M) showed competitive antagonism of the actions of pinacidil while yohimbine (1,20 ,M) did not antagonise relaxation and appeared to have actions at sites other than the KATP channel in this preparation. The relative effectiveness of the antagonists on pinacidil-induced relaxation was found to be: glibenclamide >phentolamine >tolbutamide >yohimbine, which is in agreement with studies in other tissues. The results show that many structurally diverse potassium channel openers are potent relaxants of mouse ileum. These observations are consistent with the existence of ATP-dependent K+ channels in murine intestinal muscle which, however, differ somewhat in properties from those reported for vascular muscle and pancreatic ,-cells. [source] Reversal of rocuronium-induced neuromuscular blockade by pyridostigmine in patients with Duchenne muscular dystrophyPEDIATRIC ANESTHESIA, Issue 3 2008TINO MUENSTER MD Summary 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. Methods:, Fourteen DMD patients (aged between 11 and 19 years) scheduled for elective scoliosis repair were studied. Following tracheal intubation without muscle relaxant, all patients received a single dose of rocuronium 0.6 mg·kg,1. NMB was monitored by acceleromyography at the adductor pollicis muscle. When the first twitch height (T1) of the train-of-four (TOF) had recovered to 25% seven patients received either pyridostigmine 0.1 mg·kg,1 (the anticholinergic drug with a long duration of action) or saline in a blinded manner. The times to attain TOF ratio of 0.9 were recorded. For comparison the Mann,Whitney U -test was used. Results:, Recovery to TOF ratio of 0.9 was significantly (P < 0.05) accelerated by pyridostigmine [84 (median), 57,141(range)] compared with controls (148, 84,243 min). The recovery time (time between T1 of 25% and TOF of 90%) was also significantly (P < 0.01) shortened by pyridostigmine (15, 8,49 vs 76, 43,144 min, respectively). Time to recovery of T1 to 90% was not different between the groups (108, 63,134 vs 169. 61,208 min, respectively). Conclusions:, Pyridostigmine 0.1 mg·kg,1 effectively reversed a rocuronium-induced NMB in DMD patients. [source] Neurotoxic effects of venoms from seven species of australasian black snakes (Pseudechis): Efficacy of black and tiger snake antivenomsCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 1-2 2005Sharmaine Ramasamy SUMMARY 1.,Pseudechis species (black snakes) are among the most widespread venomous snakes in Australia. Despite this, very little is known about the potency of their venoms or the efficacy of the antivenoms used to treat systemic envenomation by these snakes. The present study investigated the in vitro neurotoxicity of venoms from seven Australasian Pseudechis species and determined the efficacy of black and tiger snake antivenoms against this activity. 2.,All venoms (10 µg/mL) significantly inhibited indirect twitches of the chick biventer cervicis nerve,muscle preparation and responses to exogenous acetylcholine (ACh; 1 mmol/L), but not to KCl (40 mmol/L), indicating activity at post-synaptic nicotinic receptors on the skeletal muscle. 3.,Prior administration of either black or tiger snake antivenom (5 U/mL) prevented the inhibitory effects of all Pseudechis venoms. 4.,Black snake antivenom (5 U/mL) added at t90 (i.e. the time-point at which the original twitch height was reduced by 90%) significantly reversed the effects of P. butleri (28 ± 5%), P. guttatus (25 ± 8%) and P. porphyriacus (28 ± 10%) venoms. Tiger snake antivenom (5 U/mL) added at the t90 time-point significantly reversed the neurotoxic effects of P. guttatus (51 ± 4%), P. papuanus (47 ± 5%) and P. porphyriacus (20 ± 7%) venoms. 5.,We show, for the first time, the presence of neurotoxins in the venom of these related snake species and that this activity is differentially affected by either black snake or tiger snake antivenoms. [source] Dose-response relationship of rocuronium: A comparison of electromyographic vs. acceleromyographic-derived valuesACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2005A. F. Kopman Background: Acceleromyography (AMG) is being employed with increasing frequency as a research tool. However, there is almost no information available regarding the accuracy of values for drug potency obtained using AMG. This study was an attempt to determine if AMG-derived ED50/95 values are interchangeable with those measured with a more traditional neuromuscular monitor. Methods: Thirty adult patients were studied. Anesthesia was induced and maintained with N20, propofol, and supplementation opioid. Tracheal intubation was accomplished without muscle relaxants. Simultaneous ipsilateral AMG and EMG responses to 0.10 Hz stimulation was recorded. Following instrument calibrations, a single dose of rocuronium was administered. The first patient received a bolus of 0.17 mg kg,1 of rocuronium. Using the Hill equation with a postulated slope of 4.50, the ED50 was calculated. The second subject received a dose which approximated the calculated ED50 for patient no. 1. Successive subjects were given a dose based on the running average of the estimated ED50. Results: The AMG-derived ED50/95 values for rocuronium (0.163 ± 0.055 and 0.314 ± 0.105 mg mg,1) were virtually identical to those established using EMG (0.159 ± 0.043 and 0.306 ± 0.084 mg kg,1). While mean peak twitch depression (,T1) was the same in both groups for individual subjects ,T1 differed by ± 20% (95% confidence interval). Discussion: Acceleromyography-derived twitch heights for individual patients are not necessarily interchangeable with information obtained using electromyography. Nevertheless, acceleromyography appears to be a valid methodology for determining the drug potency when a population rather than an individual subject is being studied. [source] | ||||||||||