PubMed Health⌕ Search

Biomedical subjects

C A Rawlings

Publications and source records attributed to C A Rawlings.

At least 91 records · Page 5Linked to original sources
PubMed1977

Right ventricular enlargement in heartworm disease.

The size of the right ventricle of 15 dogs with spontaneous Dirofilaris immitis microfilaria was evaluated by thoracic radiography, electrocardiography, and right ventricular free wall weights. Based on electrocardiography and right ventricular weights, none of the 15 dogs had evidence of right ventricular hypertrophy. Based on radiography, only 2 of the 15 dogs had right ventricles of normal size. Right ventricular dilation in the absence of right ventricular hypertrophy was demonstrated. The right ventricle appears to dilate, prior to hypertrophy, in response to D immitis infestation.

Animals↗
PubMed1977

Coronary arterial anatomy of the small pony.

Ventricular weights and coronary arterial distribution and diameters were determined in 10 small adult ponies (139 +/- 32 kg). Combined ventricular weights averaged 0.52% of the body weight, with an average of 77% of the total ventricular weight being the left ventricle. The pony is right coronary predominant, with the interventricular subsinusoidal branch of the right coronary artery and interventricular paraconal branch of the left coronary artery providing comparable blood supply to the left ventricular free wall and septum.

Animals↗
PubMed1977

Susceptibility of dogs with heartworm disease to hypoxia.

Dogs with Dirofilaria immitis microfilariae and early radiographic pulmonary artery changes, but without pulmonary hypertension or clinical signs of heartworm disease, were studied. An exaggerated pulmonary hypertensive response was found in these dogs if subjected to 10% inspired oxygen. The mean pulmonary artery pressure of control dogs was increased from base line (prehypoxia control) of 15.8 +/- 2.3 (SEM) mm of Hg to 20.2 +/- 2.3 during hypoxia, and the mean pulmonary pressure of dogs with heartworm disease increased from base line of 16.4 +/- 2.4 to 26.4 +/- 1.6 during hypoxia. Pulmonary blood flow was not affected by hypoxia indicating that the increased pulmonary artery pressure was the result of increased pulmonary vascular resistance. There was an individual variation of this pulmonary hypertensive response of dogs with heartworm disease that did not appear related to the severity of the pulmonary arterial lesions, as evaluated by pulmonary arteriography.

Animals↗
PubMed1976

Hypoventilation in ponies after carotid body denervation.

Seven ponies were subjected to carotid body denervation (CD) and two ponies were sham operated (S). Measurement of arterial blood gases and arterial blood and cerebrospinal fluid (CSF) acid-base balance were made prior to and 1,2,4,9, and 17 wks after surgery in unanesthetized animals. Resting ventilation and ventilatory responsiveness to hypoxia and NaCN infusion were assessed prior to and 2,9, and 17 wks after surgery. Alveolar hypoventilation in the CD ponies was marked 1-2 wk after surgery when VE and VA were reduced 40% and 10%, respectively, from control and PaCO2 was 12-15 mmHg above control. However, the effect was not nearly as great 4, 9, and 17 wk after surgery when the PaCO2 stabilized at approximately 6 mmHg above control PaCO2. Arterial blood pH was normal in the hypercapnic CD ponies, but CSF pH remained acid relative to normal throughout the 17-wk period. Changes in ventilatory responsiveness to hypoxia and NaCN tended to parallel changes in resting ventilation. These findings suggest: 1) the carotid bodies are essential in ponies to maintain normal ventilation: 2) in CD ponies peripheral chemosensitivity is partially regained at some unestablished locus; and 3) pH compensating mechanisms in chronically hypercapnic ponies function relatively better in blood than in CSF.

Acid-Base Equilibrium↗
PubMed1975

Uteroplacental blood flow during alkalosis in the sheep.

Uteroplacental blood flow was measured by the radioactive-microsphere technique in eight near-term pregnant ewes during a normal control period and during maternal metabolic alkalosis. All measurements were made on awake, unanesthetized animals. Alkalosis, defined for this study as an arterial pH of 7.60 or greater, was produced by the oral administration of sodium bicarbonate, 3 g/kg body wt. The rise in pH thus produced was unaccompanied by significant changes in systemic arterial blood pressure and cardiac output, while maternal arterial Pco2 rose slightly from control levels. Cotyledonary blood flow declined from a control value of 1,177 ml/min to 1,025 ml/min during alkalosis. This decline of 13 percent in cotyledonary blood flow is significant (P smaller than 0.002). Blood flow to the remaining uterine tissue, or noncotyledonary uterus, did not change with alkalosis, being maintained at approximately 195 ml/min. It is concluded that maternal alkalosis, unaccompained by major changes in Pco2 and systemic arterial pressure, causes a small increase in the resistance of the uteroplacental circulation.

Alkalosis↗
PubMed1975

Static pulmonary compliance in ponies.

Static pulmonary and total compliance during expiration was measured in fifteen healthy anesthetized ponies. Mean body weight of the ponies was 140.6 kg and ranged from 83.6 to 211.4 kg. For the fifteen ponies, mean values and SD were: total compliance (Ct), 168.7 plus or minus 47.2 ml/CMH2O, and mean pulmonary compliance (Cl), 368.4 plus or minus 90.3 ml/cmH2O. Both Ct and Cl were significantly dependent on body weight, calculated surface area, height at the withers, and circumference about the chest. Repeatability of compliance measurement from day to day was confirmed by measuring compliance on consecutive days in four ponies.

Animals↗
PubMed1975

Prolonged perfusion with a membrane oxygenator in awake ponies.

Prolonged extracorporeal membrane oxygenation (PEMO) was performed in 6 adult ponies with the membrane oxygenator in vein-to-artery bypass circuit. A flow rate equal to 46 per cent of control cardiac output was diverted through the PEMO circuit of 10 to 24 hours. Three of the 6 ponies were perfused for at least 20 hours and developed no complications. Immediately following initiation of PEMO, left ventricular output decreased; however, in the interval between 6 and 24 hours, left ventricular output was increased above control levels. Aortic pressure and left ventricular work were markedly elevated during PEMO. Pulmonary ventilation and oxygen uptake also decreased initially but were elevated during later stages of bypass. Pulmonary compliance did not change, except in those studies in which problems were encountered with perfusion techniques. Hepatic glycolysis and hyperglycemia occurred and were more severe in ponies with catheter-produced thrombi. Marked diuresis, which could be attributed only partially to the hyperglycemia, was present throughout PEMO. Based on the minimal morphologic changes observed in the ponies, extracorporeal circulation diverting one half of the cardiac output through a membrane oxygenator can be safely performed for up to 24 hours.

Animals↗
PubMed1975

Activated coagulation test in normal and heparinized ponies and horses.

Activated coagulation test (ACT) was performed in 37 adult ponies and 31 adult horses. The mean ACT time of all ponies and horses was 2 minutes 38 seconds, with a standard deviation (SD) of 29 seconds. The ACT was compared with the Lee-White clotting test in heparinized ponies. The correlation of ACT with the Lee-White test was 0.95. Anticoagulation heparinized ponies during prolonged cardiopulmonary bypass was successfully monitored with the ACT. The ACT is simple and reproducible, has a definite end point, and would seem to be an ideal screening test for hemorrhagic diathesis in equine animals.

Animals↗
PubMed1975

Cardiopulmonary measurements in nonanesthetized, resting normal ponies.

Cardiopulmonary measurements were determined in 19 nonanesthetized, normal ponies. Mean values for arterial pressure, pulmonary arterial pressure, cardiac output, heart rate, packed cell volume, and hemoglobin are reported, as well as acid-base determinations of arterial blood and cerebrospinal fluid. Respiratory function test data include total ventilation, respiratory rate, alveolar ventilation, oxygen uptake, and carbon dioxide output. The data compare favorably with the available data from previous reports on ponies. Because of large day-to-day variations in total ventilation, alveolar ventilation should be measured if ponies are used in the study of pulmonary function.

Animals↗
PubMed1975

Renal clearance and excretion of endogenous substances in the small pony.

Renal clearance and excretion of endogenous substances were studied in 13 small adult ponies (152 plus or minus 93 (standard deviation (SD)) kg). Normal data of serum and urinary concentrations, clearance, and excretion of creatinine, osmolality, free water, sodium, potassium, and chloride during a 12-hour period are presented. Significant linear regressions on body weight (BW) were obtained for creatinine clearance (Ccr (ml/hr) = 127.2 times BW (kg) - 1553), osmolar clearance (Cosm(ml/hr) = 1.81 times BW (kg) m0.3), and free water (CH2O(ml/hr) = - 1.43 BW (kg) - 25.0). Compared with renal excretion of man, kidneys of ponies seem to conserve more sodium and chloride and excrete more potassium.

Animals↗