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Biomedical subjects

C E Short

Publications and source records attributed to C E Short.

At least 19 recordsLinked to original sources
PubMed1992

Advantages and guidelines for using halothane.

Halothane is a frequently used agent. Its cost is inexpensive. Halothane is a safe and effective anesthetic agent if used properly. Proper usage includes adjusting the concentration administered to produce adequate anesthesia for the procedure without excess depression of cardiac, respiratory, and neurologic function. Proper monitoring of the patient indicates the adjustments needed in concentration or needed medications or procedures to increase safe usage. Potent tranquilizers, sedatives, and analgesics used as preanesthetics during halothane anesthesia or the early postanesthetic period may produce profound changes in anesthetic concentrations required or physiologic responses to the combined medications.

Anesthesia, Inhalation↗
PubMed1992

The case for high gas flows.

High gas flows provide a higher margin of safety and fewer physiologic complications for extended anesthetic periods. The veterinarian should consider personnel, anesthetic, and monitoring equipment and the surgical procedure requiring anesthesia before making a final decision on which flow rates are appropriate.

Anesthesia, Inhalation↗
PubMed1992

Comparison of neurologic responses to the use of medetomidine as a sole agent or preanesthetic in laboratory beagles.

Different dose regimens of medetomidine (a potent alpha 2-adrenergic agonist), adding up to a combined dose of 80 micrograms/kg, were administered to laboratory beagles to determine physiologic responses including neurologic. The study was intended to determine EEG responses where sufficient sedative and analgesic effects are reached with medetomidine and in contrast its effects when used with ketamine or halothane. Cardiopulmonary responses were very similar in each dose regimen, showing the characteristic properties of single doses of 80 micrograms/kg of medetomidine. Effective sedative and analgesic duration seemed to be a function of when the largest dose was administered. Adequate additional sedative and analgesic could be gained from injections at doses of half of the initial one. The potent sedative and analgesic effects of medetomidine confirmed by neurologic evaluation supports its potential use as a premedication to general anesthesia in dogs. In this study, 2 different doses of medetomidine were also tested as premedication to both ketamine HCI and halothane anesthesia. Neorologic responses were determined at the same time cardiopulmonary parameters, anesthetic quality, and dose requirements were recorded. Medetomidine was found to have favorable qualities in conjunction with these anesthetics. Cardiopulmonary parameters remained satisfactory in both groups as preanesthetic medication prior to halothane, but no additional benefits could be seen from doses of 40 micrograms/kg medetomidine compared to 20 micrograms/kg, except a significant 30% reduction in halothane requirement. The positive chronotropic and inotropic properties of ketamine restored the medetomidine-induced bradycardia and produced a short anesthetic period of 15 to 30 min depending on the dose of medetomidine. The quality of anesthesia was better when 40 micrograms/kg medetomidine was used, but recovery was quicker with 20 micrograms/kg medetomidine. Medetomidine significantly reduced cerebral activity as demonstrated by recordings of total amplitude and frequency evaluation of the EEG with compressed spectral analysis. This analytical method was effective in confirming clinical signs of sedation, analgesia, and anesthesia in canine subjects.

Analgesia↗
PubMed1991

Effects of anticholinergic treatment on the cardiac and respiratory systems in dogs sedated with medetomidine.

Alpha 2-adrenergic agonists are often used for sedation and, or, analgesia in dogs, but they are often associated with bradycardia and in some animals with atrioventricular heart block. In this study, atropine or glycopyrrolate either helped to maintain the heart rates or were effective in increasing reduced heart rates of dogs treated with medetomidine. In the process, however, cardiac dysrhythmias often developed. These dysrhythmias were predominantly associated with the combined responses to the medetomidine and the anticholinergic agent because there were no significant changes in respiratory function. A reduced blood oxygen content or increased blood carbon dioxide can contribute to cardiac irritability. Atropine and glycopyrrolate were more effective in preventing bradycardia and had less undesirable side effects when they were given before the administration of medetomidine.

Adrenergic alpha-Agonists↗
PubMed1989

Medetomidine as a preanesthetic prior to ketamine-HCL and halothane anesthesia in laboratory beagles.

The potent sedative and analgesic effects of medetomidine confirm its potential use as a premedication to general anesthesia in dogs. In this study two different doses of medetomidine were tested as premedication to both ketamine HCl and halothane anesthesia in groups consisting of 4 laboratory beagles each. Cardiopulmonary parameters, anesthetic quality and dose requirements were recorded. Medetomidine was found to have favorable qualities in conjunction with these anesthetics. Atropine prevented the profound bradycardia and sinus arrhythmia seen with medetomidine alone. Cardiopulmonary parameters remained satisfactory in both groups, but no additional benefits could be seen from doses of 40 micrograms/kg medetomidine compared to 20 micrograms/kg, except a significant 30% reduction in halothane requirement. The positive chronotropic and inotropic properties of ketamine restored the medetomidine induced bradycardia and produced a short anesthetic period of 15-30 min depending on the dose of medetomidine. The quality of anesthesia was good in both groups, but recovery was quicker and smoother in the group with 20 micrograms/kg medetomidine.

Adrenergic alpha-Agonists↗
PubMed1989

Comparison of three different dose regimes of medetomidine in laboratory beagles.

Different dose regimes of medetomidine (a potent alpha 2-adrenergic agonist), adding up to a combined dose of 80 micrograms/kg, were administered to laboratory beagles to determine the possible superiority of any particular regime. The study was intended to mimic a clinical situation where sufficient sedative and analgesic effect was not reached with the initial dose and an additional dose would have to be administered. Cardiopulmonary responses were very similar in each dose regime, showing the characteristic properties of single doses of 80 micrograms/kg of medetomidine as reported in the literature. Effective sedative and analgesic duration seemed to be a function of when the largest dose was administered. Adequate additional sedative and analgesic effect could be gained from the second injection at doses of half of the initial one.

Adrenergic alpha-Agonists↗
PubMed1989

A comparison of xylazine, acepromazine, meperidine and medetomidine as preanesthetics to halothane anesthesia in dogs.

The preanesthetic properties of medetomidine, a novel alpha 2-adrenergic agonist, were compared to the preanesthetic properties of acepromazine, zylazine and meperidine prior to halothane anesthesia. The premedications were given to 23 randomly selected laboratory beagles in doses with sedative effects equal to the 10 micrograms/kg used in the medetomidine group. These dogs also received 0.04 mg/kg of atropine prior to the preanesthetic. A group of 7 dogs with a high medetomidine dose (40 micrograms/kg) was included in the study. Cardiopulmonary and respiratory parameters were recorded at 10 min intervals during surgical stimulus. Dogs receiving 40 micrograms/kg of medetomidine showed bradycardia, but higher blood pressures than dogs in the other groups. Adequate oxygen saturations and perfusion were recorded in all groups. The low 10 micrograms/kg dose of medetomididine had a halothane sparing effect comparable to the other premedications, while the 40 micrograms/kg of medetomidine group showed a clear decrease in halothane consumption. The sedative effect of 10 micrograms/kg of medetomidine was in some instances inadequate for proper manipulation of the dogs, but 40 micrograms/kg produced excessive sedation. Atropine was found to counteract the medetomidine induced bradycardia.

Acepromazine↗
PubMed1988

Cardiac dysrhythmias during anesthesia for cervical decompression in the dog.

In a retrospective study, the risk for cardiac dysrhythmias was evaluated in dogs undergoing ventral decompression and/or fenestration of the cervical spine (CERV) and compared with that for dogs undergoing dorsal laminectomy for decompression of the thoracic or lumbar spine (TL). The dogs in the CERV subset (48 dogs) tended to be heavier and older than the dogs in the TL subset (111 dogs). There was no apparent bias detected in treatment before anesthesia and surgery. The risk for dysrhythmias was 2.5 times greater in the CERV subset, compared with that in the TL subset (P less than 0.01). The risk for ventricular premature contraction was 3.5 times higher in the CERV group (P less than 0.05). Bradycardia was found in 6 dogs from the CERV subset and was not found in any dogs from the TL subset. A logistic model was derived from the data and may be used to evaluate the risk for dysrhythmias in similar patients undergoing similar surgery and anesthesia. This model uses age, preoperative heart rate, and site of surgery (CERV or TL) to estimate the risk.

Anesthesia↗
PubMed1987

Anesthetic and supportive management during experimental pulsatile flow perfusion studies in calves.

The purpose of this study was to determine the factors influencing successful experimental cardiopulmonary bypass studies using pulsatile flow perfusion and the medications and methodology necessary to produce successful bypass in calves. In six calves showing no cardiopulmonary pathology prior to bypass procedures, successful anesthesia and surgical intervention was accomplished. Animals were maintained on 5 hours of pulsatile flow bypass perfusion. Successful recovery from the procedures was accomplished. In two calves with pre-existing pulmonary pathology, anesthetic and surgical intervention was accomplished with the utilization of extensive anesthetic management and cardiac supportive medications until the animals could be initiated into 5 hours of pulsatile flow bypass perfusion, in spite of major pulmonary dysfunction. In these two animals, attempts to resuscitate upon termination of pulsatile flow perfusion were unsuccessful due to pre-existing excessive lesions in the lungs. This study shows a contrast between complete success of a pulsatile flow system in normal subjects versus the ultimate failure in experimental animals with pre-existing pulmonary pathology. The inability of experimental calves with a diseased lung to resume spontaneous cardiopulmonary function after the challenges of thoracic intervention indicates the unsuitability of animals with marked pre-existing pulmonary disease status for use in cardiopulmonary bypass studies.

Anesthesia, General↗
PubMed1986

Preanesthetic medications in ruminants and swine.

The use of preanesthetic agents alone or in various combinations in food animals is complex. In addition to considering the pharmacokinetics and dynamics of the medications, one must give additional consideration to the animals's temperament, its physical condition, and its environment. Also, the potential of residues from meat and milk products of animals treated with preanesthetic agents must be considered.

Animals↗
PubMed1986

Anesthetic consideration in dogs with traumatic myocarditis.

The trauma patient is commonly encountered in veterinary practice. Traumatic myocarditis has often been overlooked due to its delayed onset and preoccupation with other traumatic problems. The traumatic heart is very sensitive and in itself can cause death. Often a trauma patient requires surgery and a proper anesthetic protocol must be used which does not increase the incidence of cardiac arrhythmias. A review of anesthetic management including preanesthetic medications, induction drugs and techniques and maintenance with inhalation anesthesia reveals the need for careful selection of medications. Isoflurane was shown to be beneficial in reducing the incidence of undesirable responses of these patients.

Anesthesia↗
PubMed1986

Cardiovascular and pharmacokinetic effects of isoxsuprine in the horse.

Isoxsuprine (0.6 mg/kg) administered IV to 6 standing horses produced substantial, transient decreases in systemic blood pressure, systemic vascular resistance, and stroke volume. It also produced substantial, transient increases in heart rate, cardiac output, and purposeful movement. Plasma concentrations of isoxsuprine peaked soon after the drug was administered IV and then decreased over a 12-hour period in a biexponential manner, with distribution and elimination half-lives of 14 minutes and 2.67 hours, respectively. Total body clearance and steady-state volume of distribution were calculated to be 53.8 ml/min/kg and 10.5 L/kg, respectively. When a recommended therapeutic dosage regimen (0.6 mg/kg 2 times a day, per os) was used in 4 of these horses, changes were not detected. Isoxsuprine was not detected in plasma after the drug was given orally. We conclude that 0.6 mg of isoxsuprine/kg given orally every 12 hours is not likely to produce cardiovascular changes in the resting horse and that this is probably because plasma concentrations are not high enough to do so.

Administration, Oral↗
PubMed1986

Cardiac performance in cats after administration of xylazine or xylazine and glycopyrrolate: echocardiographic evaluations.

Cardiac performance was evaluated in 9 healthy cats sedated with xylazine. Each cat was evaluated echocardiographically before and after the administration of xylazine or xylazine and glycopyrrolate. Each cat was echocardiographically evaluated during manual restraint only (control value), after IM administration of 0.55 mg of xylazine/kg of body weight, after IM administration of 2.2 mg of xylazine/kg, and after IM administration of 0.011 mg of glycopyrrolate/kg followed 10 minutes later by IM administration of 2.2 mg of xylazine/kg. Echocardiographic indices of cardiac performance (fractional shortening, left ventricular wall amplitude, aortic amplitude, mitral valve E point septal separation) indicated a significant decrease (P less than 0.05) in the left ventricular function and heart rate after the small (0.55 mg/kg) and large (2.2 mg/kg) dosages of xylazine. With the administration of glycopyrrolate, the bradycardia was minimized, but cardiac performance was not improved. After administration of glycopyrrolate, cardiac performance decreased, but the decrease was not significant when compared with the ventricular performance of the cats after administration of the large dosage of xylazine. Compared with control values, the reduction in left ventricular function values associated with administration of xylazine or xylazine and glycopyrrolate was independent of the heart rate. Therefore, the alpha-2 adrenergic agonist xylazine has a marked depressive effect on cardiac performance in the cat, and premedication with glycopyrrolate may not completely alleviate the undesirable bradycardia, but may actually be detrimental to the cardiovascular system.

Animals↗
PubMed1985

Arterial to end-tidal CO2 tension and alveolar dead space in halothane- or isoflurane-anesthetized ponies.

The correlation between end-tidal partial pressure of CO2 (PETCO2) and arterial (PaCO2) was determined for spontaneously breathing ponies under halothane or isoflurane anesthesia. The PETCO2 was useful as a trend indicator of PaCO2 during the first 60 minutes of halothane or isoflurane anesthesia when PaCO2 values were less than 60 to 70 mm of Hg. Halothane anesthesia lasting greater than 90 minutes was associated with PaCO2 values in excess of 60 to 70 mm of Hg, a large arterial- to end-tidal PCO2 difference (PaCO2-PETCO2) and a significant increase in alveolar dead space. These effects were not seen during the same period of isoflurane anesthesia. Arterial blood gas analysis is therefore recommended during halothane anesthesia when the PETCO2 is greater than 60 to 70 mm of Hg. A decrease in alveolar capillary perfusion relative to alveolar ventilation is the most likely cause for the increase in alveolar dead space during halothane anesthesia. Based on these findings, isoflurane may be superior to halothane for prolonged anesthesia of spontaneously breathing horses.

Anesthesia, General↗