International journal of clinical monitoring and computing
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Int J Clin Monit Comput · Jan 1995
Comparative StudyDouble burst monitoring during surgical degrees of neuromuscular blockade: a comparison with train-of-four.
With double burst stimulation (DBS) it is possible to monitor more profound degrees of neuromuscular blockade than with train-of-four stimulation (TOF). It may therefore be indicated to change between DBS and TOF stimulation during moderate to profound degrees of neuromuscular blockade. Consequently, the aim of the study was to evaluate and compare the twitch height of the first twitch (D1) in DBS and the twitch height of the first twitch (T1) in TOF stimulation during moderate to profound degrees of neuromuscular blockade. Thirty-three patients scheduled for gynaecological laparotomy under general anaesthesia were studied. Mechanomyography was used for neuromuscular monitoring. The T1 twitch height before atracurium was administered served as the control twitch height (T1 control). T1 control was considered as 100%. A constant degree of neuromuscular blockade was maintained at a T1 twitch height at a point between 4 and 11% of T1 control, using a continuous infusion of atracurium. Sequences of 16 DBS and 16 TOF stimulations were given. Two different DBS patterns were examined: DBS3,350/50, (3 stimuli at 50 Hz followed 0.75 sec later by 3 stimuli at 50 Hz), and DBS3,380/40, (3 stimuli at 80 Hz followed 0.75 sec later by 3 stimuli at 40 Hz). The data were analysed by the method described by Bland and Altman. The D1 repeatability coefficients of 1.72% for DBS3,350/50 and 1.20% for DBS3,380/40 were significantly greater than the repeatability coefficient of 1.02% for T1 (p <0.05). The D1 bias of 16.7% for DBS3,350/50 was significantly less than the D1 bias of 25.7% for DBS3,380/40 (p <0.05). The limits of agreement between D1 and T1 were 0.1 to 33.3% for DBS3,350/50 and 2.9 to 48.5% for DBS3,380/40. ⋯ The repeatability of responses to DBS and TOF stimulations during moderate to profound degrees of neuromuscular blockade where only one twitch is consistently present is satisfactory. The responses to DBS were greater than responses to TOF as indicated by a positive bias of DBS. The limits of agreement between DBS and TOF responses were so wide that they cannot be used interchangeably.
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Int J Clin Monit Comput · Jan 1995
Comparative StudyAdaptive segmentation of burst-suppression pattern in isoflurane and enflurane anesthesia.
In this paper a developed novel algorithm for adaptive segmentation of Burst-suppression EEG is presented. The algorithm can detect bursts, suppression and artifacts, dividing the signal into corresponding segments. ⋯ In the second part of the paper the burst-suppression patterns of isoflurane and enflurane anesthesia are compared. It is found that bursts as well as suppression segments are shorter in enflurane anesthesia while the coefficient of variability of the segment lengths is similar for the two anesthetics.
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The location of epidural space for local anaesthetic injection can be difficult. The aim of this study was to define the mathematical function of the pressure changes in the syringe during puncture of the epidural space. Knowledge of pressure changes might be of help to the anesthetist who attempts to ascertain the location of the needle, and it is essential to the design of a device with which to locate epidural space. ⋯ Pressures within the injection system for epidural puncture can reach 1100 cm H2O. Location of the epidural space is characterized by an exponential decay to and end-residual pressure below 50 cm H2O, with a constant time of approximately 2 seconds.
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Int J Clin Monit Comput · Aug 1994
Differences in the topographical distribution of EEG activity during surgical anaesthesia and on emergence from volatile anesthetics.
Computerized processing of a 16 channel EEG allows mapping and display of cortical electrical activity in a useful mode for intraoperative monitoring. We studied the topographical distribution of EEG-activity displayed as spectral maps comparing inhalational anaesthesia with isoflurane or enflurane during surgical anaesthesia and emergence. ⋯ At near awakening the frontal and occipital dominance of delta activity disappeared in both groups and was replaced by homogeneous delta activity over the entire cortex; variations in the topographical distribution of enflurane and isoflurane were recorded in the other spectral bands. We conclude that changes in topographic EEG patterns observed during the transition from surgical anaesthesia to emergence, in particular the disappearance of frontal and occipital dominance of delta activity common to isoflurane and enflurane, may serve to detect undesirably light levels of anaesthesia.
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Int J Clin Monit Comput · Aug 1994
Comparative StudyPresentation and evaluation of a new optical sensor for respiratory rate monitoring.
A new optical sensor for respiratory rate monitoring was simultaneously compared with an acoustic sensor and a transthoracic impedance plethysmograph during normoventilation in the respiratory rate range of 9-17 breaths per minute. The response characteristics of the optical sensor were then measured during simulation of central apnoea and tachypnoea. ⋯ The response characteristics of the fibre optic sensor corresponded well with those of the acoustic sensor and impedance plethysmograph. All three methods responded rapidly to an apnoeic event.