Biomedical subjects
M C Derrington
Publications and source records attributed to M C Derrington.
Comparison of neuromuscular block in the diaphragm and hand after administration of tubocurarine, pancuronium and alcuronium.
The onset and offset of neuromuscular block in the diaphragm and in the adductor pollicis muscle were recorded using unilateral supramaximal stimulation of phrenic and ulnar nerves. Thirty patients were allocated randomly to receive tubocurarine 0.4-0.5 mg kg-1, pancuronium 0.07-0.08 mg kg-1 or alcuronium 0.2-0.3 mg kg-1. In all cases the onset of neuromuscular block occurred in the diaphragm before adductor pollicis, and spontaneous recovery was evident first in the diaphragm. There was a correlation between the time of spontaneous reappearance of twitch in the diaphragm and in the adductor pollicis only in the patients who received pancuronium (r = 0.97, P less than 0.05 for reappearance of the first twitch of the train-of-four of each muscle). The duration of paralysis in the diaphragm was less than 5 min in five patients who received tubocurarine and in one who received alcuronium; this corresponded to a period of paralysis in the adductor pollicis muscle of more than 25 min in each case.
Criteria for adequacy of reversal of neuromuscular blockade.
Explore the source record for details and available documents.
Measurement of evoked diaphragm twitch strength during anaesthesia. Adaptation and evaluation of an existing technique.
The technique of recording the mechanical response of the diaphragm after the transcutaneous stimulation of the phrenic nerve, during anaesthesia and surgery, is described in patients undergoing non-abdominal surgery. The pressure difference generated across the diaphragm after phrenic nerve stimulation was derived from the simultaneous recording of gastric and oesophageal pressures with air-filled balloon catheter systems. This was recorded as the diaphragm "twitch" in a manner similar to that of peripheral muscles. Special problems encountered in the use and the validation of the technique in the anaesthetized patient are considered.
Comparison of neuromuscular blockade in the diaphragm and the hand.
Neuromuscular blockade was recorded in the diaphragm and in the adductor pollicis muscle using unilateral supramaximal stimulation of phrenic and ulnar nerves and measurement of the mechanical effect of each. After administration of atracurium 0.4-0.5 mg kg-1 to 10 patients, both onset and recovery of neuromuscular blockade in the diaphragm occurred before that in adductor pollicis and there was a linear relationship between recovery in diaphragm and adductor pollicis. After administration of vecuronium 0.08-0.1 mg kg-1 to a further 10 patients, paralysis occurred in the diaphragm before adductor pollicis in all except one patient, in whom it occurred simultaneously. Reappearance of adductor pollicis twitch occurred in six patients after all four twitches had returned in the diaphragm, but the rate of recovery of twitch height in the diaphragm was more rapid than in adductor pollicis in every patient.
Paediatric postoperative analgesia. A comparison between caudal block and wound infiltration of local anaesthetic.
Fifty children who underwent day case herniotomy received either a caudal injection of 1 ml/kg bupivacaine 0.25% or infiltration of the wound edges at the end of surgery with 0.5 ml/kg bupivacaine 0.25%, allocated at random. Postoperative pain and demeanour were assessed initially by an observer and later by use of a parental questionnaire. Wound infiltration of local anaesthetic solution provided analgesia which was comparable to that associated with caudal block, and the incidence of side effects was similar in the two groups. Wound infiltration of local anaesthetic offers a simple, safe alternative to caudal block for provision of postoperative analgesia in this group of patients.
Evaluation of the combined effects of glycopyrrolate and neostigmine on the lower oesophageal sphincter.
The effects on the lower oesophageal sphincter (LOS) of the simultaneous administration of glycopyrrolate 0.5 mg and neostigmine 2.5 mg, when given to antagonize neuromuscular blockade, were studied in 10 healthy patients undergoing gynaecological surgery. LOS pressure and gastric pressure (GP) were measured for 20 min after the administration of the drug combination and barrier pressure (BrP) was calculated (LOS-GP). There was a significant reduction in BrP which lasted, in some patients, for the duration of the study. These results contrast with those of a similar study looking at the effects of atropine and neostigmine in which the decrease in BrP, although significant, was transient, and in which control values were regained after 5 min.
A review of studies of anaesthetic risk, morbidity and mortality.
In the past two to three decades, advancing knowledge in the areas of physiology, pharmacology and scientific technology have allowed diversification from the purely technical aspects of administration of anaesthesia towards more accurate assessment of outcome for the individual in terms of both anaesthetic-induced morbidity and mortality. In addition, elucidation of the aetiology of the morbidity and mortality produced by anaesthesia, as opposed to that from surgery or concomitant medical or surgical disease processes, is assuming increased importance as a result of the expansion in medical litigation, where anaesthetists find themselves amongst the higher risk specialties in medicine. The morbidity produced by anaesthesia is relatively easy to define for specific populations, but the prediction of risk in an isolated individual remains elusive. For example, there are many studies indicating the incidence of postoperative myocardial infarction following surgical procedures in defined groups; but for the individual patient, more sophisticated risk assessments have so far failed to predict more accurately than the well-established ASA grading system. Nonetheless, it is expected that in future, studies in this area will permit increased precision in the assessment of risk, thereby permitting better consideration by both surgeon and patient of the options available regarding surgical and non-surgical therapy. Increasing emphasis on the safer administration of anaesthesia has been greatly aided by the use of the critical incident technique. By assessing near-misses in addition to existing morbidity and mortality, the technique increases the size and extent of the database, and by removal of the reticence inherent in an anaesthetist's confession of his mistakes, it increases the reporting of potential mishaps. Amongst the useful findings to have emerged from such studies is the previously unforeseen and unsuspected observation that the most dangerous period of anaesthesia is not during induction and recovery, but during the maintenance period. However, perhaps one of the more valuable aspects of this type of methodology is its potential use in quality control and audit within departments. There are undoubted problems and universally acknowledged difficulties in epidemiological research into anaesthetic mortality. Comparison of data between studies is rendered difficult owing to variations in procedure, including its prospective or retrospective nature, the definition of death, the perioperative time period studied, and the patient and hospital populations encompassed.(ABSTRACT TRUNCATED AT 400 WORDS)
Caudal and ilioinguinal/iliohypogastric nerve blocks in children.
Explore the source record for details and available documents.
Peripheral actions of narcotics.
Explore the source record for details and available documents.
The present status of blood filtration.
The history of the development of blood transfusion and blood filtration is outlined. Clinical and experimental evidence for the efficacy of microfiltration in both small and large volume transfusions is evaluated. Though microfilters do remove the micro-aggregates from stored blood, the results of clinical studies suggest that both the debris from septic processes in the body and the formation of micro-aggregates in the blood stream triggered by processes such as complement activation play a far more important role in the pathogenesis of adult respiratory distress syndrome. If this is so the enhancement of the reticulo-endothelial system by fibronectin therapy may be indicated. It also follows that the use of microfilters is probably an unnecessary expense and, where exsanguination is a risk, may be positively dangerous. Microfilters have been found useful in the preparation of granulocyte-free transfusions after centrifugation of the blood, but their routine use for transfusions, small or large, remains to be justified.