Biomedical subjects

N S Matthews

Publications and source records attributed to N S Matthews.

42 records · Page 3Linked to original sources

PubMedDate not supplied

A comparison of injectable anesthetic combinations in horses.

Six combinations of injectable anesthetic agents were administered to six adult horses in a Latin square design. The drug combinations were xylazine-ketamine, xylazine-butorphanol-ketamine, xylazine-tiletamine-zolazepam, xylazine-butorphanol-tiletamine-zolazepam, detomidine-ketamine, and detomidine-butorphanol-ketamine. Measured variables were heart rate, respiratory rate, systolic blood pressure, arterial pH (pHa), PaCO2, PaO2, recumbency time, and number of attempts necessary to stand. Quality of induction and recovery, muscle relaxation, and response to stimulus were evaluated subjectively. The horses required significantly more attempts to stand after administration of xylazine-tiletamine-zolazepam, xylazine-butorphanol-tiletamine-zolazepam, and detomidine-ketamine than after xylazine-ketamine, xylazine-butorphanol-ketamine, or detomidine-butorphanol-ketamine. Mean recumbency times varied from 23.0 minutes with xylazine-ketamine to 41.3 minutes with xylazine-butorphanol-tiletamine-zolazepam. There were significant differences in mean heart rates at minute 15, mean respiratory rates at minutes 5, 10 and 15, and mean systolic blood pressures at minute 10 of anesthesia. There were no significant differences in pHa, PaCO2 or PaO2.

Acid-Base Equilibrium↗

PubMedDate not supplied

The effect of detomidine and its antagonism with tolazoline on stress-related hormones, metabolites, physiologic responses, and behavior in awake ponies.

Six ponies were used to investigate the effect of tolazoline antagonism of detomidine on physiological responses, behavior, epinephrine, norepinephrine, cortisol, glucose, and free fatty acids in awake ponies. Each pony had a catheter inserted into a jugular vein 1 hour before beginning the study. Awake ponies were administered detomidine (0.04 mg/kg intravenously [i.v.]) followed 20 minutes later by either tolazoline (4.0 mg/kg i.v.) or saline. Blood samples were drawn from the catheter 5 minutes before detomidine administration (baseline), 5 minutes after detomidine administration, 20 minutes before detomidine administration which was immediately before the administration of tolazoline or saline (time [T] = 0), and at 5, 30, and 60 minutes after injections of tolazoline or saline (T = 5, 30, and 60 minutes, respectively). Compared with heart rate at T = 0, tolazoline antagonism increased heart rate 45% at 5 minutes. There was no difference in heart rate between treatments at 30 minutes. Blood pressure remained stable after tolazoline, while it decreased over time after saline. Compared with concentrations at T = 0, tolazoline antagonism of detomidine in awake ponies resulted in a 55% increase in cortisol at 30 minutes and a 52% increase in glucose at 5 minutes. The change in free fatty acids was different for tolazoline and saline over time. Free fatty acids decreased after detomidine administration. Free fatty acids did not change after saline administration. After tolazoline administration, free fatty acids increased transiently. Tolazoline tended to decrease sedation and analgesia at 15 and 60 minutes postantagonism. Antagonism of detomidine-induced physiological and behavioral effects with tolazoline in awake ponies that were not experiencing pain appears to precipitate a stress response as measured by cortisol, glucose, and free fatty acids. If antagonism of an alpha-agonist is contemplated, the potential effect on hormones and metabolites should be considered.

Adrenergic alpha-Antagonists↗

PubMedDate not supplied

Detomidine-butorphanol-propofol for carotid artery translocation and castration or ovariectomy in goats.

OBJECTIVE: To determine the safety and efficacy of propofol, after detomidine-butorphanol premedication, for induction and anesthetic maintenance for carotid artery translocation and castration or ovariectomy in goats. STUDY DESIGN: Case series. ANIMALS: Nine 4-month-old Spanish goats (17.1 +/- 2.6 kg) were used to evaluate propofol anesthesia for carotid artery translocation and castration or ovariectomy. METHODS: Goats were premedicated with detomidine (10 micrograms/kg intramuscularly [i.m.]) and butorphanol (0.1 mg/kg i.m.) and induced with an initial bolus of propofol (3 to 4 mg/kg intravenously [i.v.]). If necessary for intubation, additional propofol was given in 5-mg (i.v.) increments. Propofol infusion (0.3 mg/kg/min i.v.) was used to maintain anesthesia, and oxygen was insufflated (5 L/min). The infusion rate was adjusted to maintain an acceptable anesthetic plane as determined by movement, muscle relaxation, ocular signs, response to surgery, and cardiopulmonary responses. Systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures, heart rate (HR), ECG, respiratory rate (RR), SpO2, and rectal temperature (T) were recorded every 5 minutes postinduction; arterial blood gas samples were collected every 15 minutes. Normally distributed data are represented as mean +/- SD; other data are medians (range). RESULTS: Propofol (4.3 +/- 0.9 mg/kg/min i.v.) produced smooth, rapid (15.2 +/- 6 sec) sternal recumbency. Propofol infusion (0.52 +/- 0.11 mg/kg/min i.v.) maintained anesthesia. Mean anesthesia time was 83 +/- 15 minutes. Muscle relaxation was good; eye signs indicated surgical anesthesia; two goats moved before surgery began; one goat moved twice during laparotomy. Means are reported over the course of the data collection period. Means during the anesthesia for pHa (arterial PH), PaCO2, PaO2, HCO3-, and BE (base excess) ranged from 7.233 +/- 0.067 to 7.319 +/- 0.026, 54.1 +/- 4.6 to 65.3 +/- 12.0 mm Hg, 133.1 +/- 45.4 to 183.8 +/- 75.1 mm Hg, 26.9 +/- 2.6 to 28.2 +/- 2.1 mEq/L, and -0.8 +/- 2.9 to 1.4 +/- 2.2 mEq/L. Means over time for MAP were 53 +/- 12 to 85 +/- 21 mm Hg. Mean HR varied over time from 81 +/- 6 to 91 +/- 11 beats/minute; mean RR, from 9 +/- 8 to 15 +/- 5 breaths/minute; SpO2 from 97 +/- 3% to 98 +/- 3%; mean T, from 36.0 +/- 0.6 degrees C to 39.1 +/- 0.7 degrees C. Over time, SpO2 and SaO2 did not change significantly; HR, RR, T, and PaCO2 decreased significantly; SAP, DAP, MAP, pHa, PaO2, and BE increased significantly. HCO3- concentrations increased significantly, peaking at 45 minutes. Recoveries were smooth and rapid; the time from the end of propofol infusion to extubation was 7.3 +/- 3 minutes, to sternal was 9.2 +/- 5 minutes, and to standing was 17.7 +/- 4 minutes. Median number of attempts to stand was two (range of one to four). Postoperative pain was mild to moderate. CONCLUSIONS: Detomidine-butorphanol-propofol provided good anesthesia for carotid artery translocation and neutering in goats. CLINICAL RELEVANCE: Detomidine-butorphanol-propofol anesthesia with oxygen insufflation may be safely used for surgical intervention in healthy goats.

Analgesics↗

PubMedDate not supplied

Recovery from sevoflurane anesthesia in horses: comparison to isoflurane and effect of postmedication with xylazine.

OBJECTIVE: To compare recovery from sevoflurane or isoflurane anesthesia in horses. STUDY DESIGN: Prospective, randomized cross-over design. ANIMALS: Nine Arabian horses (3 mares, 3 geldings, and 3 stallions) weighing 318 to 409 kg, 4 to 20 years old. METHODS: Horses were anesthetized on three occasions with xylazine (1.1 mg/kg), Diazepam (0.03 mg/kg intravenously [i.v.]), and ketamine (2.2 mg/kg i.v.). After intubation, they were maintained with isoflurane or sevoflurane for 90 minutes. On a third occasion, horses were maintained with sevoflurane and given xylazine (0.1 mg/kg i.v.) when the vaporizer was turned off. Horses were not assisted in recovery and all recoveries were videotaped. Time to extubation, first movement, sternal, and standing were recorded as was the number of attempts required to stand. Recoveries were scored on a 1 to 6 scoring system (1 = best, 6 = worst) by the investigators, and by three evaluators who were blinded to the treatments the horses received. These blinded evaluators assessed the degree of ataxia present at 10 minutes after each horse stood, and recorded the time at which they judged the horse to be ready to leave the recovery stall. RESULTS: Mean times (+/- SD) to extubation, first movement, sternal, and standing were 4.1 (1.7), 6.7 (1.9), 12.6 (4.6), and 17.4 (7.2) minutes with isoflurane; 3.4 (0.8), 6.6 (3.1), 10.3 (3.1), and 13.9 (3.0) minutes with sevoflurane; and 4.0 (1.2), 9.1 (3.3), 13.8 (6.5), and 18.0 (7.1) with sevoflurane followed by xylazine. Horses required a mean number of 4 (2.3), 2 (0.9), and 2 ( 1.6) attempts to stand with isoflurane, sevoflurane, and sevoflurane followed by xylazine respectively. The mean recovery score (SD) for isoflurane was 2.9 (1.2) from investigators and 2.4 (1.1) from blinded evaluators. For sevoflurane, the mean recovery score was 1.7 (0.9) from investigators and 1.9 (1.1) from evaluators, whereas the recoveries from sevoflurane with xylazine treatment were scored as 1.7 (1.2) from investigators and 1.7 (1.0) from blinded evaluators. CONCLUSIONS: Recoveries appeared to vary widely from horse to horse, but were significantly shorter with sevoflurane than isoflurane, although sevoflurane followed by xylazine was no different from isoflurane. Under the conditions of the study, recoveries from sevoflurane and sevoflurane followed by xylazine were of better quality than those from isoflurane. CLINICAL RELEVANCE: Sevoflurane anesthesia in horses may contribute to a shorter, safer recovery from anesthesia.

Adjuvants, Anesthesia↗

PubMedDate not supplied

Magnetic resonance imaging of the brain of normal neonatal foals.

Magnetic resonance imaging (MRI) was performed on the brain of 5 normal, anesthetized, neonatal (age 3-to-6 days) Quarter Horse foals. The objectives of the study were to develop a technique for imaging the brain of neonatal foals, and to ascertain their normal brain anatomy. Intravenous propofol was administered for induction and maintenance of general anesthesia. Using spin echo MR techniques, T1 weighted sagittal and transverse views, and spin density and T2 weighted transverse views were successfully made of each foal. MR images provided excellent visualization of many anatomic structures of the brain and head. MRI of the brain is feasible for selected neonatal equine patients.

Anesthesia, Intravenous↗

PubMedDate not supplied

A multisite case report on the clinical use of sevoflurane in dogs.

The purpose of this report was to evaluate the clinical safety and efficacy of sevoflurane as an inhalant anesthetic in dogs. Subjective and objective data from 196 clinical cases utilizing sevoflurane as the maintenance anesthetic was collected at three sites. After preanesthetic evaluation, the attending anesthesiologist assigned the dogs to one of the following six anesthetic protocols: protocol 1, oxymorphone premedication and thiopental induction; protocol 2, oxymorphone/acetylpromazine premedication and thiopental induction; protocol 3, xylazine/butorphanol premedication and thiopental induction; protocol 4, opioid premedication and propofol induction; protocol 5, optional premedication and mask induction with sevoflurane in oxygen; and protocol 6, optional premedication and optional induction. The average quality of induction, maintenance, and recovery was good to excellent in all protocols. The three most common side effects during maintenance and recovery were hypotension, tachypnea, and apnea. Sevoflurane produces anesthesia in dogs comparable to the other inhalation anesthetics currently used (i.e., halothane and isoflurane) for diagnostic or therapeutic procedures.

Anesthesia, Inhalation↗