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Biomedical subjects

C A Shanks

Publications and source records attributed to C A Shanks.

At least 91 records · Page 5Linked to original sources
PubMed1978

Studies of d-tubocurarine pharmacokinetics in humans and dogs.

The pharmacokinetics of d-tubocurarine was studied in man during single and multiple administrations of d-tubocurarine, and in dogs during single administrations. The simplest model consistent with out data was a two-compartment open model. The mean half-lives for the two phases in the human studies were 8.9 and 123.8 minuts. For the greyhounds these mean values were 2.8 and 77.4 minutes. The animals did not demonstrate a difference between the arterial and mixed venous concentrations of d-tubocurarine.

Adult↗
PubMed1978

Intravenous regional analgesia.

Despite its introduction in 1908, the technique of intravenous regional analgesia did not achieve popularity until it was reintroduced by Holmes in 1963. This simple technique has proved its usefulness in most operative and manipulative procedures on the extremities, including suture of lacerations, tendon repair, abscess incision and fracture work. It is more often used in the upper limb, as the arm requires a lesser total dose of the local anaesthetic agent, and does not have the same potential for precipitation of vascular pathology.

Anesthesia, Conduction↗
PubMed1977

The effect of renal failure on the disposition and neuromuscular blocking action of pancuronium bromide.

Plasma concentrations of pancuronium following single dose administration in six patients, and following multiple dose administration in four patients, all undergoing renal transplantation surgery, were measured using a fluorimetric method. A two-compartment open model was used in the pharmacokinetic analysis of the data. Comparison of the pharmacokinetic findings with data previously obtained for patients undergoing elective surgery but having normal renal function indicated that the clearance of the drug was reduced significantly in the patients with renal failure, and that in these individuals the half-life was increased significantly. Measurement of the evoked mechanical twitch response concurrently with plasma concentration monitoring of pancuronium confirmed that the prolongation of half-life in the patients with renal failure was often but not always associated with an extended duration of neuromuscular blockade and furthermore that the rate of recovery from block might also be prolonged. The clinical implications of these findings are discussed.

Adult↗
PubMed1977

Disposition kinetics of pancuronium bromide in patients with total biliary obstruction.

Plasma concentrations of pancuronium were measured in nine patients undergoing surgery because of total biliary obstruction. When compared with the averaged model-independent pharmacokinetic parameters obtained for normal patients, the terminal half-life of 270 min was more than twice normal (132 min, P less than 0.001); the plasma clearance of 59 ml min-1 was less than half the normal rate for pancuronium (123 ml min-1, P less than 0.003). These significant alterations to the pharmacokinetics of pancuronium were associated with prolongation of neuromuscular blockade. Following a bolus injection of pancuronium 6 mg, there was a mean time of 114 min (normals 70 min, P less than 0.05) before the evoked twitch response had returned to 5% of the control value. The pattern of urinary excretion of the drug and its metabolites did not differ from that of normal patients. To avoid excessive dosage during prolonged surgery for total biliary obstruction, it is recommended that supramaximal nerve stimulation be used to indicate the need for the administration of further doses of pancuronium.

Aged↗
PubMed1977

Airway pressure changes observable with constant-flow inflation and an end-inspiratory pause.

Constant-flow inflation and a prolonged end-inspiratory pause were studied, observing the airway pressures in model lungs. The technique demonstrated the changes associated with compliance, resistance and gas redistribution under varying conditions. The studies suggest that when intratracheal pressures indicate a large element of gas redistribution, constant flow inflation and end-inspiratory pause produce pendelluft, and other pressure patterns are preferable for I.P.P.V.

Airway Resistance↗
PubMed1976

Clinical pharmacokinetics of pancuronium bromide.

Plasma concentrations of pancuronium bromide have been studied in seven surgical patients following a 6 mg intravenous bolus injection of the drug for neuromuscular blockade. Concurrently, evoked muscle twitch response was monitored for each patient as a measure of the pharmacodynamic effect of the drug. The plasma decay curve for pancuronium was found to be biphasic and after rigorous statistical analysis the data were interpreted according to a 2-compartment open model. The half-life of the beta-phase varied between 89.5 and 161.5 min. The apparent volume of distribution of the central compartment ranged from 62.9 to145.5 ml/kg and the plasma clearance from 57.6 to 187.3 ml/min. At the first sign of recovery from neuro-muscular blockade the mean pancuronium plasma level was found to be 0.218 mcg/ml. The mean duration of action as measured from time of onset of paralysis to 20% recovery was 83.4 min with the plasma level at 20% being 0.169 mcg/ml corresponding to 45.4% of dose remaining to be eliminated from the body.

Adult↗
PubMed1976

Respiratory mechanics with constant flow inspiration. A comparison of two measurement techniques.

Resperatory compliance and resistance were measured during positive pressure ventilation in anaesthtized, paralysed dogs. Airway pressures measured during constant-flow inspiration allowed the calculation of pulmonary and chest-wall resistances, and static and non-static compliances. Contiguous studies of dynamic compliance and resistance allowed comparison of the two techniques, and the level of agreement was reasonalble. Cconstant-flow inflation of the lungs allows a simple means of measuring respiratory mechanics, and should be valid for the observation of short-term changes in the apnoeic patient.

Airway Resistance↗
PubMed1975

Heat gain in the treatment of accidental hypothermia.

In two cases of accidental hypothermia, heated humidification of the inspired gases and warming of fluids administered intravenously was associated with an increase in the deep body (core) temperatures at rates of 0-5 degrees to 1-0 degrees C per hour. The first case demonstrated that heat was transferred selectively to the body core, as temperatures here rose during the first three hours of treatment, while skin temperatures remained low. The second patient gained less than 0-1 degrees C per hour when treated "passively" by means of surface insulation with unheated blankets. The introduction of "active" measures was followed by a more rapid gain. It is suggested that heat supplied to the body core by these measures provides effective additions to metabolic production, particularly when the deep body and cardiac temperatures are at their lowest.

Bedding and Linens↗
PubMed1975

Pharmacokinetics of chlormethiazole in humans.

The pharmacokinetics of chlormethiazole have been studied in six healthy volunteers following an intravenous infusion of the drug. The log. plasma concentration-time curve of chlormethiazole after cessation of the infusion was found to be curvilinear and was fitted therefore, by a bi-exponential equation computed by non-linear least squares regression analysis. Half-lives for the initial alpha-phase (0.54+/-0.05 h) and the terminal beta-phase (4.05+/-0.60 h) were calculated together with other pharmacokinetic parameters of the two compartment open model. An explanation for the discrepancy between the presently reported plasma half-lives and those appearing in the literature has been presented. The pharmacokinetic treatment of the plasma concentration-time data obtained following intravenous infusion also enabled the prediction that the maximal systemic availability of an orally administered dose of chlormethiazole would be of the order of 15%.

Administration, Oral↗
PubMed1975

Mean skin temperature during anaesthesia: an assessment of formulae in the supine surgical patient.

The mean skin temperature was calculated from measurements made in 22 patients under general anaesthesia. The results from 11 different formulae were compared with a system involving 15 temperature sites on the skin, each given a weighting factor in proportion to the fraction of total surface area which it represented. If accuracy is required, the mean skin temperature should be measured in surgical patients using a formula which involves at least 10 skin sites. Incorrect estimation of stored body heat results from an erroneous value for the mean skin temperature, and this occurred more frequently when the number of skin sites was reduced.

Anesthesia, General↗
PubMed1975

A comparison of two heated water-bath humidifiers.

The performance of two heated water-bath humidifiers was examined in terms of airway temperatures and humidities. These were the simple heated tank (Marshall and Spalding, 1953) and the Fisher and Paykel No. 328 (Spence and Melville, 1972), both of which had the potential to deliver gases at temperatures above 40 degrees C, and with a moisture content in excess of 50 mg/litre. The major advantage of the No. 328 was its heating wire in the delivery tube. This lessened or prevented condensation within the tube, and allowed the water bath to be maintained at lower temperatures. Independent heat controls for the water bath and the delivery tubing allow precision of humidities in the gases provided for inspiration through an artificial airway. When condensation is prevented, the temperature of the saturated gases leaving the humidifier limits the absolute humidity supplied. Monitoring and adjustment of airway temperature of the patient then allows selection of temperature and relative humidity in the inspired gas.

Anesthesia, Inhalation↗
PubMed1975

Heat balance during surgery involving body cavities.

Three groups of adult patients were anaesthetized for elective intra-abdominal surgery. In one group, patients were ventilated with dry anaesthetic gases, and these patients all lost heat. In the second group humidification was used to annul respiratory heat exchange, and these patients lost heat initially but tended to regain heat during anaesthesia. The third group, in addition to humidification, had surface insulation and all these patients gained heat. It is suggested that conservative methods which negate heat loss are able to prevent hypothermia by the retention of metabolically produced heat.

Abdomen↗
PubMed1975

Control of heat balance during arterial surgery.

Patients were studied to quantitate methods used to prevent heat loss during vascular surgery. A combination of techniques limiting heat loss were shown to prevent hypothermia. In addition it was shown that heat balance in patients undergoing vascular surgery did not differ from that in patients undergoing other forms of surgery.

Arteries↗
PubMed1975

Accurate volume ventilation of neonates with maintenance of humidification.

A method is presented for producing adequate humidification and accurate volume ventilation of neonates. This was effected by pressurizing the humidifier and fresh gas flow up to the T-piece. By using a ventilator which acted as a timed occluder of the T-piece, the system functioned as an accurate flow generator. Its precision of ventilation was confirmed with a neonatal test lung.

Electrocardiography↗