Biomedical subjects
Publications and source records attributed to F R Ellis.
Two patients who developed hypermetabolic reactions during anaesthesia and surgery and who were suffering from arthrogryposis multiplex congenita are reported and it is proposed that the reaction is distinct from malignant hyperthermia and independent of the anaesthetic agents used. The implications for anaesthetists involved in the management of patients with arthrogryposis multiplex congenita are discussed.
Conditions for insertion of the laryngeal mask were assessed following induction of anaesthesia with either propofol 2.5 mg/kg or thiopentone 4.0 mg/kg in 80 patients premedicated with diazepam 10 mg. Insertion following induction with thiopentone resulted in a greater incidence of gagging (p less than 0.01). The use of additional induction agent, where necessary, resulted in no ultimate significant difference between the groups for the provision of satisfactory conditions.
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The myotonic response of the masseter muscles following various doses of suxamethonium was measured using a unique myotonometer in 50 apparently healthy patients, the majority of whom showed a myotonic response which lasted less than 100 s. A maximum increase in masseter tone was found to be greater than 1 kg in five patients, and 12 patients developed a maximum tone of greater than 500 g. An increased masseter tone of this degree might be interpreted as "masseteric muscle spasm" by the anaesthetist. The value of masseteric muscle "spasm" as an early sign of malignant hyperthermia is questioned.
Muscle relaxation rate following a tetanic stimulus of adductor pollicis muscle was measured prospectively in 26 patients potentially susceptible to malignant hyperthermia (MH) the day before a muscle biopsy was obtained for MH in vitro screening. Eleven subjects were found to be MH susceptible (MHS) and 15 subjects MH-negative (MHN). In all patients, relaxation rate was recorded at three different temperatures of the skin overlying adductor pollicis (30, 34 and 38 degrees C) achieved by a small surface heating unit placed over the thenar eminence. The MHS group exhibited slightly higher relaxation rate at 34 and 38 degrees C compared with the MHN group and this difference was accentuated with increasing temperature, but was not statistically different. The results of the present study suggest that relaxation rates are normal in MHS individuals under physiological conditions and cannot be used diagnostically for MH screening.
As anaesthetists have become more aware of malignant hyperthermia the mortality rate has fallen, but concommitantly the number of dubious and aborted cases has increased. All probands who developed a suspected malignant hyperthermia reaction during anaesthesia and subsequently underwent muscle biopsy were classified according to the clinical presentation. A probability for malignant hyperthermia can be calculated, using the classification, for each type of clinical presentation; this varied from 0.96 to 0.07. Certain clinical features were found to be of more value as predictors than others; these included a high creative kinase and myoglobinuria. The accuracy of prediction depends on a clear contemporaneous description of the clinical events.
We have assessed in normal subjects the validity of using hand heating to obtain "arterialized" venous blood by biochemical comparison of results for "arterialized" venous and true arterial (radial artery) blood samples. The heating regimen involved placing one hand in an air-heated box at 45-50 degrees C for 45 min. This method produced blood that was "arterialized" for lactate, PCO2, HbO2, and Hb but not for ammonia or PO2; it had no effect on determinations of pyruvate or glucose in plasma. Despite using a lower air temperature than previous workers, we observed thermal injury in one volunteer. Further, there was considerable between-subject variation in the effect of hand heating on blood gases. This suggests that blood gases should be measured in the "arterialized" samples at regular intervals from the start of hand heating in each patient to determine whether maximal "arterialization" has been achieved, to avoid making misleading biochemical measurements. Given the wide range in degree of observed "arterialization," we question the validity of this method.
Malignant hyperthermia has been recognised for over 30 years. In this time its apparent incidence and importance have changed. The developments and the likely role of MH in the future are discussed, as is the impact and importance of genetic screening to anesthetic practice.
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Stress has been suggested as a factor involved in the development of a malignant hyperthermia (MH) reaction. This study has compared the hormonal response of a group of patients susceptible to MH (MHS), with that of a control group, during diagnostic muscle biopsy under general anaesthesia. Preoperative adrenal cortical reserve was assessed using the Short Synacthen Test (SST). There was no significant difference between the groups in their hormonal response to the procedure, both groups showing a peroperative reduction in plasma cortisol concentration from an initially high value, and the SST was within accepted normal limits for both groups. It was concluded that patients susceptible to MH have normal adrenal cortical reserve and responded normally to the psychological and surgical stress encountered during this study.
Winnie and co-workers described a technique of blocking the lateral cutaneous nerve of thigh, femoral and obturator nerves using one injection of local anaesthetic into the fibrous sheath surrounding the femoral nerve. We studied 40 patients undergoing biopsy of vastus medialis for investigation of malignant hyperpyrexia, for onset, quality and recovery from this block. The patients were assigned in a random double-blind fashion to receive 0.6 ml kg-1 of one of two anaesthetic solutions: 1% lignocaine with 1 in 100,000 noradrenaline or 0.25% bupivacaine. Bupivacaine produced a similar onset time but longer duration of action compared with lignocaine. Median peak plasma concentrations of six patients in each group did not approach values associated with toxicity. This study demonstrated a 12.5% and 87.5% partial and complete femoral nerve block, respectively, and a 67.5% success rate for lateral cutaneous nerve of thigh using Winnie's technique. There was no clinical evidence of obturator nerve block.
The occurrence of masseteric muscle spasm (MMS) in children is thought to be frequent and to be associated usually with malignant hyperpyrexia (MH). We have found a lower incidence of MMS in children and 50% had no muscle abnormality. Clinical features that support a diagnosis of MH include high serum creatine kinase (CK) concentration and the presence of myoglobinuria. There is evidence to suggest that suxamethonium does increase jaw tone in adults and children, and an exaggerated response may be taken clinically to be MMS. However, MMS should still be regarded as an early warning sign of MH.
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1. Premedication with 30 mg buccal morphine or 10 mg intramuscular morphine was evaluated in 40 healthy women undergoing major gynaecological surgery. 2. Buccal administration of morphine produced lower plasma morphine concentrations than intramuscular injection of morphine (P less than 0.01). 3. The mean systemic availability of the buccal tablet, during the first 5 h after administration, was approximately 3% relative to that of the intramuscular preparation. 4. Poor absorption of buccal morphine resulted in inadequate sedation prior to surgery and poor post-operative analgesia. 5. Patients experienced difficulty with the buccal formulation of morphine; tablet bitterness and failure to dissolve were particular problems.
This paper reports three investigations of the suggested relationship between sudden infant death syndrome (SIDS) and malignant hyperpyrexia (MH). In the first study 151 MH-susceptible families completed a questionnaire designed to identify the incidence of SIDS within their own pedigree. In the second study 106 SIDS families completed a questionnaire designed to identify the incidence of anaesthetic related problems. In the third study, 14 SIDS parents were subjected to muscle biopsy and in vitro halothane contracture and caffeine contracture screening for susceptibility to MH. From the results of the three studies it can be concluded that there is no association between SIDS and MH.
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Sixty-one women undergoing major gynaecological surgery received slow release morphine (MST) 60 mg, with placebo, hyoscine 0.6 mg or diazepam 10 mg, by mouth 2 h before surgery. Plasma morphine concentrations reached a steady level usually within 3 h after administration of MST, and did not increase after surgery unless supplementary opioid was given. Hyoscine delayed morphine absorption. Before operation no fewer than 50% of patients were sedated after MST alone, but this increased to 85% after MST and diazepam. Similarly, only the combination MST and diazepam produced anxiolysis. Postoperative mood was unhappier after MST and hyoscine. Emesis occurred in 40-57% of patients, and was not reduced by hyoscine. Therefore premedication with MST alone did not produce reliable sedation or anxiolysis. A combination of hyoscine and MST premedication cannot be recommended, as it did not produce sedation, anxiolysis or antiemesis and hyoscine may have delayed morphine absorption.
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