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Biomedical subjects

B M Weaver

Publications and source records attributed to B M Weaver.

At least 37 records · Page 2Linked to original sources
PubMed1981

Solubility of halothane in equine tissues at 37 degrees C.

The solubilities of halothane at a concentration of 0.77% v/v in 5% carbon dioxide in air at 37 degrees C were determined for a variety of equine tissues. The mean values for the tissue/gas partition coefficients for visceral tissue taken from 36 horses were 5.42 for whole brain, 4.82 for grey matter, 7.41 for white matter, 4.18 for myocardium, 2.76 for lung, 8.51 for liver, 3.21 for kidneys, 2.66 for gastrointestinal tract, 1.77 for blood and 2.45 for spleen. The mean coefficients for eight different muscles taken from 23 horses ranged from 2.43 for extensor carpi radialis to 4.91 for psoas major. The values obtained were, with the exception of liver and brain, consistently lower than values in the literature for rabbit, dog, man and ox. Statistical analysis indicated that the condition of a horse was important in determining the solubility of halothane in its liver and muscles. The type of sex of a horse appeared to be important only in respect of the solubility of halothane in the gastrointestinal tract.

Animals↗
PubMed1981

Tissue composition and halothane solubility in the horse.

The halothane muscle/gas partition coefficients at 37 degrees C for 26 samples of eight different muscles from four horses were found to depend significantly on the fat content of the muscle sample with a regression coefficient of 1.913 (SEM 0.109) per per cent ether-extractable fat content. The blood/gas partition coefficients in 24 horses showed a significant dependence on plasma triglyceride concentration (regression coefficient 0.00084 (SEM 0.00033) per mg dl-1), an insignificant positive dependence on plasma free and total cholesterol concentration and, in a multiple regression analysis, a negative dependence of borderline significance on packed cell volume (regression coefficient -0.01 (SEM 0.005) per per cent p.c.v.).

Animals↗
PubMed1981

Regional pulmonary perfusion in horses: a comparison between anaesthetised and conscious standing animals.

The regional perfusion to the lungs of 14 ponies was studied using radioactively labelled microspheres injected intravenously. It was found that within half an hour of induction of anaesthesia the perfusion to the dependent lung had decreased significantly from the values in the standing animal. When anaesthesia was maintained for more than two and a half hours, however, the lung perfusions were not significantly different from the standing values when the animals were lying in lateral or supine recumbency.

Anesthesia↗
PubMed1980

NdYAG laser photocoagulation in the dog stomach.

Considerable discussion still centres around the relative merits of the Argon and Neodymium Yttrium Aluminum Garnet (NdYAG) lasers for the endoscopic treatment of gastrointestinal haemorrhage, although both are undoubtedly effect. We have carried out experiments to elucidate which factors determine the safety and efficacy of NdYAG laser photocoagulation. Histological studies on normal gastric mucosa showed that the depth of tissue damage depended mainly on the total incident laser energy, whereas the effectiveness of photocoagulation of induced gastric ulcers in heparinised animals depended on the laser power and the exposure time used. Optimum haemostasis with minimum tissue damage was obtained using pulses of 300 to 500 ms duration with energies of 25 to 40 J. We consider these parameters safe and effective for use in pilot clinical studies.

Animals↗
PubMed1980

Nature and extent of histological changes induced by argon laser photocoagulation in canine gastric mucosa.

The tissue changes in canine gastric mucosa caused by exposure to an argon laser beam vary from mild mucosal oedema to complete cell destruction. Intermediate degrees of damage cause an inflammatory cell response with the formation of granulation tissue, particularly in the submucosa. The rate of healing is similar to that after other forms of injury to the gastric mucosa. Cell destruction at the surface of the mucosa starts with energies greater than 8 Joules on any one spot, and occurs at greater depths as the energy is increased but, unless cells are actually destroyed, the extent of histological damage is limited to a zone 1 mm lateral to, or below, the area exposed to the laser beam. Haemostasis is achieved by thermal contraction of bleeding vessels and of the surrounding tissue, thrombosis only occurring as a secondary effect.

Animals↗
PubMed1979

Body composition of the horse.

Seventeen horses were dissected and their organs and tissues weighed. The results of these dissections are presented together with comparisons of the data with that already available in the literature. Predictive equations for organs and tissue weights are also given which were derived by comparison of linear and allometric regression models using 4 different body weight indices.

Adipose Tissue↗
PubMed1979

Argon laser photocoagulation in the dog stomach.

Laser photocoagulation is one of a number of methods currently under investigation for the endoscopic treatment of gastrointestinal haemorrhage. The Argon ion and Neodymium Yttrium Aluminium Garnet (Nd YAG) lasers are theoretically suitable as the beam from each may be transmitted via a flexible fibre. Argon laser photocoagulation has been shown to be effective and we have elucidated which factors determine its safety and efficacy. Studies on normal canine gastric mucosa showed that the depth of tissue damage depended chiefly on the total incident laser energy on any one spot, and that below 50 J the risk of perforation was extremely low. The energy density was much less important. The haemostatic effect depended more on the laser power. In artificial bleeding gastric ulcers in heparinised dogs the most effective level was 7--9 W, at which 22 out of 23 ulcers (96%) stopped bleeding completely, compared with one out of 12 controls. Photocoagulation was achieved in these cases with energies well within the safe limits. The procedure was effective endoscopically, and these results justify early clinical studies in man.

Absorption↗
PubMed1979

The density of equine tissue at 37 degrees C.

The density of the following equine tissues was measured: white and grey brain matter, myocardium, lung parenchyma, liver, spleen, gastrointestinal tract and contents, renal medulla and cortex, muscle, fat, tendon and bone. Statistical analysis indicated that there were highly significant differences in the values for density between horses and between tissues within horses. Values for density of eight different muscles were obtained for 18 horses and these were shown to differ highly significantly between horses and between muscles within horses. The values for splenic density differed highly significantly between those for knackery killed horses and for the barbiturate killed post morten room horses.

Animals↗
PubMed1979

Distribution of cardiac output in anaesthetised horses.

The radioactive microsphere method was used to determine the distribution of cardiac output in six anaesthetised ponies. Simultaneous measurements of cardiac output allowed calculation of the tissue perfusions (ml/min/100 g). Allowing for the fact that measurements were carried out on animals under halothane anaesthesia and which had respiratory acidosis, the results were comparable with published values for other species.

Anesthesia, Inhalation↗
PubMed1978

Priapism after sedation, neuroleptanalgesia and anaesthesia in the horse.

The paper reports 6 cases of priapism with subsequent protrusion and paresis after neuroleptanalgesia and anaesthesia in horses. Five were ultimately treated by amputation of the penis but the sixth horse is responding satisfactorily to conservative treatment at the time of writing. Causative factors, preventive measures and possible methods of treatment are discussed.

Amputation, Surgical↗
PubMed1977

Acute respiratory distress in the dog associated with paraquat poisoning.

An acute respiratory distress syndrome in 10 adult dogs was usually preceded by vomiting, anorexia and lethargy followed, after a short interval, by dyspnoea. The dyspnoea became increasingly severe, despite oxygen therapy, and cyanotic respiratory failure ensued. All 10 dogs died or were killed after illnesses lasting between one and eight days. Necropsies revealed pulmonary congestion, oedema, collapse and haemorrhage with loss of alveolar epithelial cells. Early alveolar fibrosis was also found. Paraquat was identified in post mortem samples from four of the 10 dogs.

Animals↗
PubMed1975

Ventilation and cardiovascular studies during mechanical control of ventilation in horses.

Eleven out of 12 horses were underventilating while breathing spontaneously during halothane anaesthesia with high arterial carbon dioxide tensions. In addition, large alveolar to arterial oxygen tension gradients were found to be present. Mechanically, controlled ventilation with an intermittent positive pressure of 20-30 cm H2O reduced arterial carbon dioxide levels to normal. The alveolar to arterial oxygen gradients did not increase and in some cases decreased. These (A - a) Po2 gradients were due mainly to true shunt of the order of 30 per cent and not to ventilation perfusion inequality.

Anesthesia, Inhalation↗