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Biomedical subjects

K W Clarke

Publications and source records attributed to K W Clarke.

At least 37 records · Page 2Linked to original sources
PubMed1996

Cardiopulmonary effects of desflurane in the dog during spontaneous and artificial ventilation.

The cardiopulmonary effects of desflurane at end tidal concentrations of 10.3, 12.9 and 15.5 per cent during either spontaneous or artificial ventilation were studied in five beagle dogs. Desflurane anaesthesia resulted in tachycardia and a decrease in arterial blood pressure which were not significantly related to the end tidal desflurane concentrations or the mode of ventilation. At an end tidal desflurane concentration of 15.5 per cent there was a significant increase in central venous and pulmonary arterial wedge pressures and, with artificial ventilation, a reduction in cardiac output and stroke volume when compared with similar measurements at an end tidal desflurane concentration of 10.3 per cent. When allowed to breathe spontaneously, the dogs panted at times when they were lightly anaesthetised, but their respiration was depressed to a varying extent at the highest end tidal desflurane concentration. The induction of anaesthesia with desflurane was smooth, and the quality of anaesthesia during maintenance was excellent. There was one episode of a transient tachyarrhythmia associated with the measurement of cardiac output, but no other side effects were observed.

Anesthesia, General↗
PubMed1996

The actions of medetomidine may not be mediated exclusively by alpha 2-adrenoceptors in the equine saphenous vein.

Spirals of endothelially denuded equine saphenous vein were used to study the pre- and post-junctional effects of medetomidine in vitro. The pD2 values were calculated for noradrenaline (6.7 +/- 0.1), phenylephrine (5.6 +/- 0.1), BHT 920 (6.2 +/- 0.2) and UK 14304 (5.7 +/- 0.2). Medetomidine produced a biphasic response, with a pD(2)1 of 8.2 +/- 0.1 and a pD(2)2 of 5.7 +/- 0.1 in the equine saphenous vein (n = 6). Prazosin (10(-7) M) significantly shifted the second phase of the medetomidine concentration-response curve to the right (pD(2)1 was 8.1 +/- 0.2 and pD(2)2 was 5.0 +/- 0.2, P < 0.05). Rings of equine saphenous vein were electrically stimulated to investigate the pre-junctional effects of medetomidine. Increasing concentrations of the alpha 2-adrenoceptor agonist BHT 920 reduced the response to electrical stimulation in a concentration dependent manner to a maximum of 40 +/- 5%, whereas medetomidine (0.1-100 nM) caused a concentration dependent enhancement to a maximum of 490 +/- 150%. These results suggest alpha 1- and alpha 2-adrenoceptors are functional in the equine saphenous vein, but that medetomidine is not acting exclusively as an alpha 2-adrenoceptor agonist.

Adrenergic alpha-Agonists↗
PubMed1995

How common is heart failure? Evidence from PACT (prescribing analysis and cost) data in Nottingham.

BACKGROUND: The aim of the study was to determine the prevalence of heart failure in Nottinghamshire by an analysis of prescriptions for loop diuretics. METHODS: An observational study was carried out in the Nottingham Health District, on the basis of Prescribing Analysis and Cost (PACT) data relating to nearly 400,000 kg of frusemide prescribed in the year 1991-1992 and general practitioner (GP) records on two groups of patients (total 903) prescribed frusemide. RESULTS: The total amount of frusemide prescribed on a daily basis in Nottinghamshire in 1,048,566 mg. The mean daily dose of frusemide per patient is 60 mg and the median dose 40 mg. There are between 13,107 and 26,214 patients taking frusemide in Nottinghamshire. Fifty-six per cent of patients prescribed loop diuretics by their GP fulfil diagnostic criteria for heart failure. CONCLUSION: The prevalence of heart failure in Nottinghamshire estimated from loop diuretic prescribing increases from 0.1 per cent in the age-group 30-39 years to 5.45 percent in patients aged over 90 years.

Adult↗
PubMed1994

Do women with acute myocardial infarction receive the same treatment as men?

OBJECTIVE: To determine whether women with acute myocardial infarction in the Nottingham health district receive the same therapeutic interventions as their male counterparts. DESIGN: Retrospective study. SETTING: University and City Hospitals, Nottingham. PATIENTS: All patients admitted with a suspected myocardial infarction during 1989 and 1990. MAIN OUTCOME MEASURES: Route and timing of admission to hospital, ward of admission, treatment, interventions in hospital, and mortality. RESULTS: Women with myocardial infarction took longer to arrive in hospital than men. They were less likely to be admitted to the coronary care unit and were therefore also less likely to receive thrombolytic treatment. They seemed to have more severe infarcts, with higher Killip classes, and had a slightly higher mortality during admission. They were less likely than men to receive secondary prophylaxis by being discharged taking beta blockers or aspirin. CONCLUSIONS: Survival chances both in hospital and after discharge in women with acute myocardial infarction are reduced because they do not have the same opportunity for therapeutic intervention as men.

Adrenergic beta-Antagonists↗
PubMed1994

Implication of prescriptions for nitrates: 7 year follow up of patients treated for angina in general practice.

OBJECTIVE: To determine the demand placed on local cardiological services by patients prescribed nitrates for ischaemic heart disease. DESIGN: A follow up study of a cohort of patients identified in 1985. SETTING: Nottingham Health District. PATIENTS: Four hundred and ninety nine patients prescribed nitrates in 1985 for presumed ischaemic heart disease. MAIN OUTCOME MEASURES: Referral to medical outpatients, admittance to hospital with chest pain, cardiological investigations, and mortality. RESULTS: Over the seven year period 26% of patients were admitted urgently with chest pain and 15% were referred to the medical outpatient department--a referral rate of 6% a year. 4% of patients had an exercise test and 6% a coronary angiogram. The death rate was 6% a year and a higher proportion died of cardiovascular causes than would be expected in the general population. CONCLUSIONS: Prescription of nitrate is useful in the determination of the prevalence of ischaemic heart disease. Most patients with angina are still treated within the community, and the rate of specialist investigation remains low.

Adult↗
PubMed1994

Evidence of inadequate investigation and treatment of patients with heart failure.

OBJECTIVE: To determine the referral rates to hospital and level of investigation of patients with heart failure, and to assess whether they are receiving optimum management. DESIGN: A retrospective survey. SETTING: Nottingham Health District. PATIENTS: 505 patients receiving loop diuretic treatment prescribed by their general practitioner. MAIN OUTCOME MEASURES: Referral to hospital as an inpatient or outpatient for assessment of assumed cardiac failure; investigations--electrocardiography, chest radiography, and echocardiography; treatment with angiotensin converting enzyme inhibitors. RESULTS: Only 56% of patients prescribed loop diuretics fulfilled the diagnostic criteria for heart failure. Of these, 74% had been referred to hospital, of whom 80% had had an electrocardiograph, 75% a chest radiograph, but only 31% an echocardiogram. Only 17% of patients with heart failure were being treated with angiotensin converting enzyme inhibitors in conjunction with loop diuretics. CONCLUSIONS: Patients with heart failure in the Nottingham Health District are not being adequately investigated or receiving the optimum treatment.

Aged↗
PubMed1992

A comparison of the sedative effects of three alpha 2-adrenoceptor agonists (romifidine, detomidine and xylazine) in the horse.

The sedative effects of a new alpha 2-adrenoceptor agonist, romifidine, were compared with those of xylazine and detomidine. Five horses were treated with two doses of romifidine (40 micrograms/kg body weight and 80 micrograms/kg body weight), two doses of detomidine (10 micrograms/kg body weight and 20 micrograms/kg body weight) and one dose of xylazine (1 mg/kg body weight) given by intravenous injection using a Latin-square design. The dose of 80 micrograms/kg romifidine appeared equipotent to 1 mg/kg xylazine and 20 micrograms/kg detomidine, although at these doses both xylazine and detomidine had a shorter action. Detomidine 20 micrograms/kg and xylazine both produced greater lowering of the head and a greater degree of ataxia than romifidine at either dose. Romifidine produced sedation similar to that of the other drug regimes. The effect upon imposed stimuli was similar.

Acoustic Stimulation↗
PubMed1991

Comparison of the sedative effects of medetomidine and xylazine in horses.

The sedative effects in horses of the new alpha 2 agonist medetomidine were compared with those of xylazine. Four ponies and one horse were treated on separate occasions with two doses of medetomidine (5 micrograms/kg bodyweight and 10 micrograms/kg bodyweight) and with one dose of xylazine (1 mg/kg bodyweight) given by intravenous injection. Medetomidine at 10 micrograms/kg was similar to 1 mg/kg xylazine in its sedative effect but produced more severe and more prolonged ataxia, and one animal fell over during the study. Medetomidine at 5 micrograms/kg produced less sedation but a similar degree of ataxia to 1 mg/kg xylazine.

Animals↗
PubMed1989

The use of medetomidine/fentanyl combinations in dogs.

The sedative effects of medetomidine at doses of 20 and 40 micrograms/kg im given alone or followed 16-18 min later by fentanyl (2 micrograms/kg iv) was investigated in 6 bitches of mixed breeds. The higher dose of medetomidine alone caused the greater degree of sedation, but two bitches were only lightly sedated with either dose. Side effects noted in some cases included apparent pain on injection, vomiting on induction of sedation, bradycardia, slowing of respiratory rate, cyanosis and muscular twitching. The intravenous injection of fentanyl caused a marked increase in depth of sedation in all animals, inducing a condition similar to neuroleptanaesthesia in which the eyes were rotated downward and the pedal reflex abolished. Slight twitching and sensitivity to sound occurred immediately after fentanyl injection, but this was transient. The cardiopulmonary effects of medetomidine (40 micrograms/kg im) followed 20 min later by either fentanyl (2 micrograms/kg iv) or a saline placebo were investigated in 4 beagle dogs. Medetomidine caused bradycardia, hypotension and reduced respiratory rate, inducing an intermittent respiratory pattern. The iv injection of fentanyl did not further alter the heart or respiratory rate or blood pressure. However there was a small but significant decrease in arterial oxygen tension and rise in arterial carbon dioxide tension. indicating some respiratory depression. We conclude that the use of intravenous fentanyl to dogs already sedated with medetomidine could prove useful in clinical cases where the initial sedation with medetomidine has proved inadequate.

Adrenergic alpha-Agonists↗
PubMed1988

Combined use of detomidine with opiates in the horse.

The effects of administration of one of four opiates (pethidine 1 mg/kg bodyweight (bwt), morphine 0.1 mg/kg bwt, methadone 0.1 mg/kg bwt, and butorphanol 0.05 mg/kg bwt) given intravenously to horses and ponies already sedated with detomidine (10 micrograms/kg bwt) were investigated. Behavioural, cardiovascular and respiratory effects of the combinations were compared with those occurring with detomidine alone. Addition of the opiate increased the apparent sedation and decreased the response of the animal to external stimuli. At doses used, butorphanol produced the most reliable response. Side effects seen were increased ataxia (greatest following methadone and butorphanol) and excitement (usually muzzle tremors and muscle twitching). Following pethidine, generalised excitement was sometimes seen. Marked cardiovascular changes occurred in the first few minutes after morphine or pethidine injection, but within 5 mins cardiovascular changes were minimal. Following morphine or pethidine there was a significant increase in arterial carbon dioxide tension. Fourteen clinical cases were successfully sedated using detomidine/butorphanol combinations.

Animals↗
PubMed1987

Propofol as an intravenous anaesthetic agent in dogs.

Studies in dogs with an emulsion formulation of the intravenous anaesthetic, propofol, showed that induction of anaesthesia was smooth and it was possible to maintain anaesthesia by intermittent injection. The mean dose for induction of anaesthesia in unpremedicated dogs was 5.95 mg/kg body-weight. When no premedication was administered anaesthesia was maintained by a total dose of approximately 0.806 mg/kg/minute. Premedication with between 0.02 and 0.04 mg/kg of acepromazine reduced the mean induction dose by about 30 per cent and the maintenance dose by more than 50 per cent. In 68 unpremedicated dogs given one dose, recovery was complete in a mean time of 18 minutes and after maintenance of anaesthesia by intermittent injection in 65 dogs the mean recovery time was 22 minutes from administration of the last dose. Premedication with acepromazine did not produce statistically significant increases in these recovery times. The quiet, rapid and complete recovery proved to be most valuable in cases where the animal had to be returned to the owners' care with the minimum of delay.

Acepromazine↗
PubMed1986

Incidence, diagnosis and treatment of postoperative complications in colic cases.

A survey of 259 surgical colic cases revealed that over 50 per cent of fatalities occurred in the postoperative period. Postoperative ileus and circulatory/endotoxaemic shock accounted for 70 per cent of these deaths. Other less important complications were salmonellosis, long bone fracture, adhesions, haemorrhage, laminitis, wound infection and ischaemic muscle damage. Close monitoring of postoperative progress is necessary to enable early diagnosis and treatment. Recent developments in understanding of the pathophysiology of endotoxic shock and ileus may lead to more successful treatment regimes. The possibilities include the use of cyclooxygenase inhibitors, anti-endotoxin hyperimmune serum and dopamine antagonists.

Animals↗