PubMed · 6259567
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C R Corum, L Garcia, J D Repko. 1981. Screening for lead absorption.. https://pubmed.ncbi.nlm.nih.gov/6259567/
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INDICATION: Sensitivity to neuromuscular blocking agents differs between individuals, and residual neuromuscular blockade is a common postoperative problem. Clinical signs such as head lift, hand grip, and inspiratory force are suitable means of showing residual blockade. However, an awake and cooperative patient is needed. Therefore, in clinical practice it is advantageous to use the responses evoked by a nerve stimulator. SITES OF NERVE STIMULATION AND DIFFERING MUSCLE RESPONSE: In clinical anesthesia, the ulnar nerve is the most popular site. The response is evaluated by feeling the contractions of the adductor pollicis muscle. This muscle shows a slow onset of blockade and is highly sensitive to neuromuscular blocking agents. Therefore, the chance of overdosing the patient is decreased and during recovery additional safety is gained, as it can be safely assumed that at the time of normalization of the thumb twitches no residual blockade exists in the diaphragm or larynx. On the other hand, absent twitches of the adductor pollicis using train-of-four stimulation do not preclude intraoperative activity of more resistant muscles such as the diaphragm. RECORDING OF EVOKED RESPONSES AND PATTERNS OF NERVE STIMULATION: In clinical anesthesia, tactile evaluation of the muscle response is the usual method. Mechanomyography (Myograph) with a force transducer is used as the reference standard. This method, as well as the measurement of acceleration (Accelograph, TOF-Guard) and electromyography (Relaxograph) are mainly tools for teaching and research. Different patterns of nerve stimulation are used: during induction, single-twitch stimulation at 1Hz; during profound blockade, post-tetanic count stimulation (PTC); surgical blockade is evaluated using train-of-four stimulation (TOF); and recovery is followed by double-burst stimulation (DBS). Using simple train-of-four stimulation during recovery, a device is needed with a registering capacity to accurately determine a TOF-ratio > 0.7. CONCLUSIONS: Relaxometry allows monitoring of neuromuscular function independently of the patient's cooperation, and should be standard. In the intensive care unit, relaxometry helps to minimize the risk of overdosing. However, muscular weakness can persist despite adequate drug dosage. Relaxometry is only part one of a concept. Intubating and operating conditions are highly dependent on the depth of anesthesia, and the risk of postoperative residual blockade can be minimized by using short or medium action drugs.
In this study it has been found that exposure of photosensitized erythrocytes to short, intense electric pulses, resulted in cell lysis. When erythrocytes were photosensitized with increasing concentrations of the photosensitizer, hematoporphyrin derivative (HPD), and subjected to electric pulses in the absence of light, cell lysis increased with increasing photosensitizer concentration. In addition, it has been shown that exposure of photosensitized erythrocytes to electric field pulses of increasing field strength resulted in increased cell lysis. Light activation of photosensitized erythrocytes, pre-treated with electric pulses, also resulted in increased cell lysis. The results presented here suggest that HPD may be activated in the absence of light using electric pulses. We suggest that enhancement of activation by electric field stimulation may find application in increasing the overall efficiency of photodynamic therapy.
We simulate wave propagation in the whole heart containing a local inhomogeneity whose properties mimic some properties of cardiac tissue during the acute phase of infarction. The dynamics of cardiac tissue is described by a FitzHugh-Nagumo (FHN) model. We show that two or several short-period stimulations of the heart lead to the development of a three-dimensional vortex ring, which is a temporal source of high frequency waves. The vortex ring is located near the boundary of the infarction and induces wave patterns which appear as several focal wave sources on the epicard and endocard. We have traced the filament of the vortex and show its dynamics. Continuous stimulation of the heart at high frequency resulted in the Wenckebach effect.