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Biomedical subjects

S W Eicker

Publications and source records attributed to S W Eicker.

28 records · Page 2Linked to original sources
PubMed1990

Cardiovascular and respiratory effects of inspired oxygen fraction in halothane-anesthetized horses.

Anesthesia of equids is associated with pulmonary dysfunction. Cardiovascular and respiratory effects of inhalation anesthetic agents and duration of anesthesia have been studied, using oxygen as the carrier gas. To our knowledge, the effects of inspired oxygen have not been determined. We studied the cardiovascular and respiratory effects of 2 inspired oxygen fractions (0.30 and greater than 0.85) in 5 laterally recumbent, halothane-anesthetized horses. Mean systemic arterial blood pressure, cardiac output, central venous pressure, pulmonary arterial pressure, arterial pH, and arterial base excess were similar in horses of the 2 groups during 4 hours of anesthesia at constant end-tidal halothane concentration. End-tidal partial pressure of CO2, arterial partial pressure of CO2 and O2, and alveolar-to-arterial O2 tension difference were greater in horses exposed to the higher oxygen concentration. On the basis of the data obtained, we suggest that greater hypoventilation and ventilation/perfusion mismatch occur when horses are breathing high-oxygen fraction. Arterial partial pressure of O2 was not different between the 2 groups of horses after they were disconnected from the anesthesia circuit and allowed to breathe room air. Horses recovered from anesthesia without complications.

Anesthesia, Inhalation↗
PubMed1990

Endomyocardial biopsy in cats.

A technique for transvenous endomyocardial biopsy of the right ventricle was developed and evaluated for safety and efficacy in anesthetized healthy cats positioned in left lateral recumbency. At least 6 endomyocardial biopsy specimens were obtained from the right ventricle or interventricular septum of 11 cats. In 4 cats, the right jugular vein was torn during attempts to pass the introducing catheter into the right ventricle; however, in only 1 cat did this preclude catheter passage. This cat's heart was biopsied via the left jugular vein. Except for damage to the jugular vein, complications were infrequent, and the biopsy procedure was well tolerated by all cats.

Animals↗
PubMed1990

Modified transvenous endomyocardial biopsy technique in dogs.

A technique for transvenous endomyocardial biopsy of the right ventricle was developed and evaluated for safety and efficacy in healthy dogs and dogs with dilated cardiomyopathy positioned in lateral recumbency. This technique allowed acquisition of multiple biopsy specimens from the right ventricle of each of 22 hemodynamically normal dogs and 40 of 42 dogs with congestive heart failure. In 2 dogs with dilated cardiomyopathy, transvenous access to the right ventricle could not be achieved, but left ventricular biopsy was performed without complication. Complications were infrequent, and dogs recovered to at least their baseline status within 48 hours. Evaluation of the efficacy and complication rate of the procedure with each of the 2 biopsy instruments currently available identified no differences between them.

Animals↗
PubMed1989

The effects of locomotion on respiratory muscle activity in the awake dog.

Using 6 chronically-instrumented awake dogs, we characterized the response of the respiratory muscles to mild and moderate treadmill exercise in terms of (1) the magnitude and timing of the EMGs of the costal and crural diaphragm, triangularis sterni and transverse abdominal muscles, and (2) the concomitant changes in esophageal (PE) and gastric (PG) pressures during treadmill exercise. Dogs wore a bivalved breathing mask which constrained breathing frequency and prevented some of the exercise-induced hypocapnia. Inspiratory and chest expiratory muscle EMGs increased linearly with a 1.5-fold tidal volume (VT) change during exercise. Abdominal muscle recruitment occurred during most exercise levels and exhibited (1) phasic activity coincident with footplant and (2) tonic activation evidenced by a baseline shift in PG and EMG activities. During control, inspiratory and expiratory flow preceded the onset of respiratory muscle EMG activity, but during exercise, electrical activation of these muscles coincided with the onset of mechanical flow. We conclude that phasic and tonic activation of expiratory muscles during exercise in the dog is significantly influenced by both respiratory and locomotory requirements. These patterns of expiratory muscle recruitment may assist inspiration by lengthening inspiratory muscles through decrements in end-expiratory lung volume and by passive recoil of the rib cage and abdominal compartments.

Animals↗
PubMed1989

The effects of chemical versus locomotory stimuli on respiratory muscle activity in the awake dog.

Using 6 chronically instrumented awake dogs, we contrasted the ventilatory and respiratory muscle EMG responses to steady-state normoxic hypercapnia with those occurring at similar levels of ventilation during steady-state treadmill exercise. During hypercapnia, increases in ventilatory output were primarily due to increments in VT whereas during exercise, increases in minute ventilation were due primarily to increases in frequency. With either hyperpnea, augmentation of both inspiratory and expiratory muscle EMG activity occurred but only diaphragmatic EMG activity was strongly correlated with tidal volume changes in both conditions. Using both EMGs and thoraco-abdominal pressures, we found that with increasing chemical or locomotory stimuli, during inspiration (1) diaphragmatic EMG activation occurred sooner relative to the onset of mechanical flow and (2) that respiratory muscles other than the diaphragm contributed significantly to the generation of inspiratory flow and VT either actively or passively through recoil. Post-inspiratory inspiratory activity of the crural diaphragm shortened relative to control in hypercapnia but did not change in exercise. Finally, during mild hyperpneas, end-expiratory lung volume did not change significantly in either hypercapnia or exercise but decreased at the higher levels of hyperpnea only during exercise. This may reflect differences not in the magnitude of phasic expiratory muscle activity, but rather in the degree of tonic abdominal muscle activation between the two conditions.

Animals↗
PubMed1986

Oxygen toxicity in the infant rhesus monkey lung. Light microscopic and ultrastructural studies.

Eight monkeys were anesthetized with ketamine hydrochloride and positive pressure ventilated with greater than 95% oxygen (tests) or room air (controls) for 24 hours. Two test monkeys and one control were treated with E. coli endotoxin (500 micrograms/kg) IV at the start of the study and after 12 hours. Histopathological changes in the lung parenchyma were evaluated using light and electron microscopy. Interstitial edema was detected as early as 24 hours after the onset of hyperoxia but there was no significant increase in the alveolar-capillary distance (blood-air barrier). Morphologic signs of oxygen toxicity further included swelling and disruption of vascular endothelium, and swelling of alveolar Type II pneumocytes. There was no difference in the number of macrophages per high power field between the four groups but significant differences were observed in the number of neuroepithelial bodies (NEBs) per cm2 and mast cells per high power field at the light microscopic level. Treatment with endotoxin did not protect against oxygen toxicity and was associated with an exacerbation of the morphological alterations in the lung parenchyma and swelling of alveolar Type I pneumocytes.

Air↗
PubMed1985

Estimation of quantitative proteinuria in the dog, using the urine protein-to-creatinine ratio from a random, voided sample.

The correlation between 24-hour urine protein excretion and the protein-to-creatinine ratio (U-P/C) from random, voided urine specimens was assessed in 16 healthy Beagles (9 to 11 months old) and in 14 dogs with suspected renal proteinuria. Initially, a voided urine specimen was obtained from each dog, and the U-P/C was determined. An attempt was not made to standardize the time of collection of the voided urine. Subsequently, each dog was placed in a metabolism cage, and 24-hour urine specimens were collected for quantitative protein analysis. The Coomassie blue technique was used to measure urine protein. The correlation between the U-P/C and the 24-hour urine protein excretion (mg/kg/24 hr), evaluated by linear-regression analysis, was found to be significant (r = 0.975, P less than 0.01). These results substantiate previous findings and indicate that random, voided urine specimens may be used to compute the ratio and to accurately reflect 24-hour urinary protein loss in the dog.

Animals↗
PubMed1984

Equine plasma banking: collection by exsanguination.

A procedure was developed for the collection, preparation, storage, and administration of equine plasma. The technique involved exsanguination of anesthetized donor horses via carotid artery catheterization with a large-bore cannula. Blood was collected into plastic bags, allowed to settle by gravity, then transferred into storage bags and frozen. These were quickly thawed when needed.

Animals↗
PubMedDate not supplied

Effects of atropine and glycopyrrolate on esophageal, gastric, and tracheal pH in anesthetized dogs.

Atropine, glycopyrrolate, or saline solution was administered before anesthesia in a blinded, controlled study of 40 dogs scheduled to undergo surgery. Effects of treatment on esophageal, gastric, and tracheal pH were measured with an intraluminal pH meter. Preanesthetic administration of atropine and glycopyrrolate had no effect on esophageal, gastric, or tracheal pH but did result in increased heart rate. Thoracotomy procedures resulted in decreased intraluminal esophageal pH and increased heart rate. Esophageal pH at the level of the thoracic inlet decreased over the duration of surgery.

Anesthesia↗