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Biomedical subjects

J H Chamberlain

Publications and source records attributed to J H Chamberlain.

At least 19 recordsLinked to original sources
PubMed1996

Inpatient vs. outpatient pain management: results of a randomised controlled trial.

Inpatient and outpatient cognitive behavioural pain management programmes for mixed chronic pain patients were compared. Patients were randomly allocated to the 4 week inpatient programme or to the 8 half day per week outpatient programme, or to a waiting list control group. Staff, teaching materials, and setting were the same for the two treatment groups. Patients were assessed pre-treatment, and at 1 month after discharge, and treated patients also at 6 months and 1 year after discharge, by assessors blind to treatment group; assessments included physical, functional and psychological measures, and medication use. In total, 121 mixed chronic pain patients (mean age 50 years; mean chronicity 8.1 years) were included in the study, following medical examination to ensure that no further medical treatment was appropriate. There was no change in the control group; inpatients and outpatients, comparable before treatment, both made significant improvements in physical performance and psychological function, and reduced medication use. Inpatients made greater gains, and maintained them better at 1 year; they also used less health care than outpatients. There were no outstanding predictors of improvement other than treatment group.

Ambulatory Care↗
PubMed1993

Evaluation of a cognitive behavioural programme for rehabilitating patients with chronic pain.

The aim of this prospective longitudinal study was to evaluate an inpatient cognitive behavioural pain management programme for patients with chronic pain. A physical and psychological assessment of patients was carried out before and after treatment, and at one and six months follow up. A total of 212 patients with disabling chronic pain of mean duration 10.5 years, for whom no further medical or psychiatric treatment was appropriate or available, were admitted; their mean age was 50 years and 65% were women. The four week programme was delivered by a multidisciplinary team of two psychologists, a physiotherapist, nurse, occupational therapist and anaesthetist. The main components of therapy included: education, teaching behavioural and cognitive skills, a stretch and exercise programme, medication reduction, goal setting and pacing, and relaxation training. Outcome measures assessed quality of life, physical performance (for example walking speed), pain intensity and distress, depression severity and confidence. Assessment immediately after treatment revealed significant improvements on all measures. Improvements were well maintained at six month follow up. Cognitive behavioural treatment can be of value in improving the day-to-day functioning and quality of life of patients with chronic pain for whom conventional medical treatments have apparently failed.

Adult↗
PubMed1987

Cardiorespiratory and metabolic effects of dopamine and dobutamine infusions in dogs.

The effects of iv dobutamine and dopamine infusions were studied at six incremental doses (range 5 to 160 micrograms/kg.min) in two groups of five dogs. Dobutamine decreased the systemic vascular resistance (SVR), without significant changes in mean arterial pressure (MAP), or pulmonary vascular resistance (PVR). Dopamine increased MAP, SVR, and PVR, except for a decrease at 10 micrograms/kg.min. Both drugs produced dose-related increases in cardiac output and venous admixture; however, with dopamine the dose-response curve reached a plateau at doses greater than 40 micrograms/kg.min. While the oxygen consumption (VO2) increased progressively in both groups, the oxygen availability ratio (DO2/VO2) and arteriovenous oxygen content difference (CaO2 - CvO2) were maintained mainly by increased cardiac output in the dobutamine group and hemoglobin concentration in the dopamine group. Thirty minutes after termination of drug infusions, the DO2/VO2 dropped, and CaO2 - CvO2 increased significantly in both groups. These changes were mainly due to sustained high VO2; however, in the dopamine group, a larger imbalance resulted from further decreases in cardiac output to levels below the control value.

Animals↗
PubMed1983

Respiratory gas exchange before and after cardiac operations.

The changes in oxygen consumption and carbon dioxide production were measured both before and for 6 hours after a variety of cardiac operations. Core and peripheral temperatures were measured simultaneously. Oxygen consumption was initially similar to preoperative values but rose over the next 2.5 hours by an average of 31% above basal. Carbon dioxide production was initially higher than preoperative values, then declined briefly, and finally showed an average increase above basal of 29%. Core temperature rose from an initially slightly depressed level to a maximal level 4 hours postoperatively at an average rate of 0.4 degrees C/hr. It was not possible to separate cause and effect between the temperature and oxygen consumption increases, but more effective postoperative temperature control might limit metabolic demands at a critical time postoperatively.

Aged↗
PubMed1982

A simply constructed system for mean blood flow measurement.

Blood flow measuring equipment and cardiac bypass pumps must be calibrated against a direct measurement of flow using timed collection. Single vessel timed collection systems have problems associated with their use. Repeated determinations of flow cannot be made rapidly, and frothing and fluid surface instability in the collecting vessel render the timing of a measured volume flow difficult and inaccurate. Collecting vessels which fill from the bottom may exert a changing back pressure on the source of flow. A semi-automated timed collection system is presented which overcomes these disadvantages. It has been used successfully to calibrate electromagnetic flowmeters and heart bypass pumps with 1% reproducibility or better. The system has also been used to measure coronary sinus flow directly in canine right heart bypass preparations.

Animals↗
PubMed1981

Myocardial depression by ketamine. Haemodynamic and metabolic observations in animals.

This study investigated the effect of ketamine on myocardial function. In dogs the drug was infused directly into the left main coronary artery. The concentration chosen was similar to the peak concentration found following a bolus intravenous injection. A mild depression of inotropic state was found which recovered completely after stopping the infusion. Myocardial depression was confirmed in a guinea pig Langendorff preparation. No changes in high energy phosphates were found in these hearts after 45-60 minutes of perfusion with ketamine in the perfusion medium. This study confirms that myocardial depression occurs with ketamine but suggests that it is unlikely to be of clinical significance. Depletion of high energy phosphates did not seem to be the cause of the depression.

Adenosine Triphosphate↗
PubMed1981

Measurement of respiratory gas exchange during artificial respiration.

This paper reports a new system for the continuous measurements of respiratory gas exchange in ventilated subjects. It involves mixing some of the inspired gas with all of the expired gas and withdrawing the mixture at a constant rate through a dry gas meter that measures the flow. The inspired gas and expired gas mixtures are sampled and O2 and CO2 concentrations measured with a paramagnetic gas analyzer and a capnograph, respectively, to an accuracy of 0.01%. Evidence is presented to confirm the necessary stability and sensitivity of these instruments. It is possible to use the system with high inspired O2 concentrations, with ventilators where there is incomplete separation of inspired and expired gas, and in the presence of intermittent mandatory ventilation, positive end-expiratory pressure, and continuous airway pressure. The system was compared with the N2-dilution method and with the collection of expired gas in a Douglas bag in dog experiments and with patients in the intensive therapy unit. Excellent correlation between these methods was found in all circumstances.

Air Pressure↗
PubMed1980

Dobutamine, isoprenaline and dopamine in patients after open heart surgery.

Dobutamine, a new synthetic catecholamine, has been developed as a more specific inotrope and is reported to have less effect on heart rate and peripheral vascular resistance than other catecholamines. Reports of its effects after cardiotomy have cast doubt on this idea. We have compared the haemodynamic effects of dobutamine with isoprenaline (Group I) and with dopamine (Group II) in early postcardiotomy patients. In both groups a dose response curve was evaluated (dopamine and dobutamine were given at 1.25, 2.5, 5.0 and 10.0 microgram/kg/min; isoprenaline at 0.005, 0.01, 0.02 and 0.04 microgram/kg/min). In Group I both drugs caused significant increases in cardiac index at the highest dose level only. At that level isoprenaline was associated with a significantly higher heart rate than dobutamine and a significantly lower systemic vascular resistance. Similarly, in Group II, both drugs caused significant increases in the cardiac index only at the highest dose level. However, the heart rate at this dose was significantly higher with dobutamine. Dopamine caused no changes in heart rate at any dose level. Neither drug was associated with any alteration of systemic vascular resistance. No changes in stroke volume, left atrial pressure or pulmonary vascular resistance were found in either group. The rise in cardiac output was caused mainly by tachycardia.

Adult↗
PubMed1980

Phenylalkylamines with potential psychotherapeutic utility. 2. Nuclear substituted 2-amino-1-phenylbutanes.

A series of 2-amino-1-(4-substituted-2,5-dimethoxyphenyl)butanes (Table V) was prepared as analogues of (R)-2-amino-1-(2,5-dimethoxy-4-methylphenyl)butane (1a). 1-(2,5-Dimethoxyphenyl)-2-(N-phthalimido)butane (7) was utilized as a synthetic intermediate common to many of the target compounds. Animal data are presented indicating that most of these analogues have low hallucinogenic potential. Selected compounds were compared with 1a in an avoidance-response acquisition model which differentiates between 1a and the human hallucinogens DOM (2a) and DOET (2b). Structure-activity relationships of these analogues are discussed.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗
PubMed1980

Hypotension and myocardial metabolism. Drug-induced hypotension and the heart: a comparison between halothane and nitroprusside.

This study investigated the effect of hypotension produced by nitroprusside or halothane on haemodynamics and myocardial metabolism. It is postulated that halothane might influence the balance of supply and demand of oxygen to the heart more favourably than nitroprusside. The results in six open-chested dogs do not support this view. Despite the fact that the two drugs lowered the mean arterial pressure by radically different mechanisms, the reduction in demand for oxygen by the heart seemed to be matched by a similar reduction in supply with both drugs. No evidence of anaerobic metabolism or increased a-v O2 content differences was found. It is concluded that the reduction in mean arterial pressure to these levels by either method is not likely to impair myocardial energetics in healthy hearts with normal coronary anatomy.

Anesthesia, Inhalation↗
PubMed1979

A model of left ventricular function in the denervated heart.

A model has been formulated for the function of the denervated left ventricle. Using the model it is possible to generate realistic waveforms for aortic flow, aortic pressure, left ventricular volume and left ventricular pressure over a wide range of simulated haemodynamic conditions. The effect of changes in contractile state is introduced through the concept of left ventricular pumping capacity. Model results compare well with similar data obtained from denervated hearts in open-chest dogs anaesthetized with halothane under positive pressure ventilation. Simulation of changes in contractile state shows excellent agreement with data published by previous investigators.

Animals↗
PubMed1977

Behavioral suppressant effects of clonidine in strains of normotensive and hypertensive rats.

The behavioral effects of orally administered clonidine were investigated in Long--Evans (LE), Sprague--Dawley (SD) or Kyoto Wistar (KW) rats assumed to be normotensive and in NIH spontaneously hypertensive (SH) rats. Although clonidine (0.05-1 mg/kg) resulted in the same qualitative effect, i.e., depression of motor activity, the dose of clonidine required to depress motor activity to 50% of control levels (ED50) tended to vary according to strain. An analysis of variance of the dose response curves for the four strains of rats indicated a significant strain effect. When the effects of clonidine on food-reinforced operant responding were investigated it was observed that SD and SH rats differed with regard to rate and temporal pattering of IRT greater than 20 sec responding. Although oral administration of clonidine (0.006-0.1 mg/kg) produced similar percentage decreases from control in SH and SD rats, and analysis of the temporal patterning of responding indicated differences in responsiveness to the behavioral effects of clonidine. These studies demonstrate strain-related differences in responsiveness to the behavioral suppressant effects of clonidine. Marked differences between genetically hypertensive rats and rats assumed to be normotensive were not evident.

Animals↗