Echocardiographic reference values in healthy cats sedated with ketamine hydrochloride

An M-mode echocardiographic examination was performed in a consistent manner in 30 clinically healthy cats under light ketamine hydrochloride sedation. There was a significant linear relationship between increasing body size and increasing cardiac dimensions for several echocardiographic values. Positive correlation existed between body weight and body surface area with aortic root, left ventricular caudal wall thickness (LVCW), interventricular septal thickness (IVS), IVS/LVCW, and mean velocity of circumferential fiber shortening (Vcf); there was a negative correlation between body weight and body surface area with left ventricular ejection time (LVET). Body surface area also correlated positively with percentage of ventricular minor axis dimensional change (% delta D). Positive correlations were recorded between left ventricular end-diastolic dimension (LVEDD) and left ventricular endsystolic dimension (LVESD), LVESD and LVET, LVCW and IVS, LVET (calculated by LVCW motion) and LVET (calculated by aortic valve motion), % delta D and Vcf, heart rate and Vcf, and Vcf (calculated using aortic valve motion to compute LVET) and Vcf (using LVCW motion to compute LVET). There were negative correlations between LVEDD and % delta D, LVEDD and Vcf, LVESD and Vcf, LVET and Vcf, LVET and heart rate, LVET and % delta D. Significant differences were recorded between means of echocardiographic reference values generated in this and other studies, except for LVESD.     

Xylazine and tiletamine-zolazepam anesthesia in horses

The cardiopulmonary and anesthetic effects of xylazine in combination with a 1:1 mixture of tiletamine and zolazepam were determined in 6 horses. Each horse was given xylazine IV or IM, as well as tiletamine-zolazepam IV on 4 randomized occasions. Anesthetics were administered at the rate of 1.1 mg of xylazine/kg of body weight, IV, 1.1 mg of tiletamine-zolazepam/kg, IV (treatment 1); 1.1 mg of xylazine/kg, IV, 1.65 mg of tiletamine-zolazepam/kg, IV (treatment 2); 1.1 mg of xylazine/kg, IV, 2.2 mg of tiletamine-zolazepam/kg, IV (treatment 3); and 2.2 mg of xylazine/kg, IM, 1.65 mg of tiletamine-zolazepam/kg, IV (treatment 4). Tiletamine-zolazepam doses were the sum of tiletamine plus zolazepam. Xylazine, when given IV, was given 5 minutes before tiletamine-zolazepam. Xylazine, when given IM, was given 10 minutes before tiletamine-zolazepam. Tiletamine-zolazepam induced recumbency in all horses. Duration of recumbency in group 1 was 31.9 +/- 7.2 (mean +/- 1 SD) minutes. Increasing the dosage of tiletamine-zolazepam (treatments 2 and 3) significantly (P less than 0.05) increased the duration of recumbency. Xylazine caused significant (P less than 0.05) decreases in heart rate and cardiac output and significant (P less than 0.05) increases in central venous pressure and mean pulmonary artery pressure 5 minutes after administration. Respiratory rate was decreased. Arterial blood pressures increased significantly (P less than 0.05) after xylazine was administered IV in treatments 1 and 3, but the increases were not significant in treatment 2. Xylazine administered IM caused significant (P less than 0.05) increases in central venous pressure and significant (P less than 0.05) decreases in cardiac output.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiopulmonary effects of a ketamine hydrochloride/acepromazine combination in healthy cats.

The effect of a ketamine hydrochloride/acepromazine combination on the cardiopulmonary function of 11 healthy cats was studied. Test parameters included cardiac output, measured by thermodilution, heart rate, respiratory rate, arterial blood pressure (systolic, diastolic and mean) and arterial blood gas analysis. Values for systemic vascular resistance, cardiac index and stroke volume were calculated. The cardiac output, cardiac index, stroke volume, arterial blood pressure and arterial blood pH decreased significantly (p less than 0.006). The arterial CO2 increased significantly (p less than 0.006). All changes occurred during the five to 45 minute postinduction time period. The heart rate, respiratory rate, arterial O2 and systemic vascular resistance were not significantly altered. The anesthetic regime maintained an adequate plane of surgical anesthesia for 30-45 minutes.     

Xylazine and ketamine anaesthesia in the dromedary camel under field conditions

The effects of either xylazine (0.25 mg/kg) intramuscularly, ketamine (5.5 mg/kg) intramuscularly, or a mixture of xylazine (0.15 mg/kg) and ketamine (2.5 mg/kg) intramuscularly on sedation, analgesia, cardiac and respiratory rates, body temperature and muscle relaxation were studied in the domesticated dromedary camel. Either drug used separately was suitable for sedation and analgesia in the camel. However, the mixture of xylazine and ketamine was superior to either drug used alone. Camels which received the combination of xylazine and ketamine had fewer effects on cardiac and respiratory rates and better analgesia. In addition, they showed better muscle relaxation, less central nervous system irritability and shorter recovery times than camels sedated with ketamine alone.     

Cardiovascular effects of propofol alone and in combination with ketamine for total intravenous anesthesia in cats

OBJECTIVE: To compare cardiovascular effects of equipotent infusion doses of propofol alone and in combination with ketamine administered with and without noxious stimulation in cats. ANIMALS: 6 cats. PROCEDURE: Cats were anesthetized with propofol (loading dose, 6.6 mg/kg; constant rate infusion [CRI], 0.22 mg/kg/min) and instrumented for blood collection and measurement of blood pressures and cardiac output. Cats were maintained at this CRI for a further 60 minutes, and blood samples and measurements were taken. A noxious stimulus was applied for 5 minutes, and blood samples and measurements were obtained. Propofol concentration was decreased to 0.14 mg/kg/min, and ketamine (loading dose, 2 mg/kg; CRI, 23 microg/kg/min) was administered. After a further 60 minutes, blood samples and measurements were taken. A second 5-minute noxious stimulus was applied, and blood samples and measurements were obtained. RESULTS: Mean arterial pressure, central venous pressure, pulmonary arterial occlusion pressure, stroke index, cardiac index, systemic vascular resistance index, pulmonary vascular resistance index, oxygen delivery index, oxygen consumption index, oxygen utilization ratio, partial pressure of oxygen in mixed venous blood, pH of arterial blood, PaCO2, arterial bicarbonate concentration, and base deficit values collected during propofol were not changed by the addition of ketamine and reduction of propofol. Compared with propofol, ketamine and reduction of propofol significantly increased mean pulmonary arterial pressure and venous admixture and significantly decreased PaO2. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of propofol by CRI for maintenance of anesthesia induced stable hemodynamics and could prove to be clinically useful in cats.     

Cardiovascular effects of propofol alone and in combination with ketamine for total intravenous anesthesia in healthy cats

This study was designed to compare the cardiovascular effects of equipotent maintenance of anesthetic doses (determined in a previous study) of propofol and propofol/ketamine, administered with and without noxious stimulation. Six healthy adult cats were anesthetized with propofol (loading dose 6.6 mg kg^?1, infusion 0.22 mg kg^?1 minute^?1), and instrumented to allow determination of blood gas and acid–base balance and measurement of blood pressures and cardiac output. The propofol infusion was continued for a further 60 minutes after which measurements were taken prior to and during application of a noxious stimulus. The propofol infusion was decreased to 0.14 mg kg^?1 minute^?1, and ketamine (loading dose 2 mg kg^?1, infusion 23 µg kg minute^?1) was administered. After a further 60 minutes, measurements were again taken prior to and during application of a noxious stimulus. The data were analyzed, using several Repeated Measures anova (first, ketamine/propofol and noxious stimulation were each treated as within‐subject factors; secondly, the levels of these two factors were combined into a single within‐subject factor). Mean arterial pressure, CVP, PAOP, SI, CI, SVRI, PVRI, oxygen delivery index, oxygen consumption index, oxygen utilization ratio, PvO₂, pHa, PaCO₂, bicarbonate concentration, and BD values collected during propofol administration were not changed by addition of ketamine and reduction of propofol concentration or by application of a noxious stimulus under propofol alone. Application of a noxious stimulus under propofol alone did, however, significantly increase HR and PaO₂, and these responses were not blunted by the addition of ketamine. Compared with propofol, administration of ketamine and reduction of propofol concentration significantly increased PAP and venous admixture, and significantly decreased PaO₂. Although application of a noxious stimulus to cats under propofol alone did not significantly change CVP, SI, CI, PVRI, oxygen delivery index, and oxygen consumption index, significant differences were found in these variables between propofol and propofol/ketamine. In conclusion, propofol alone provided cardiopulmonary stability; addition of ketamine did not improve hemodynamics but did decrease oxygenation.     

Xylazine, diazepam and midazolam premedicated ketamine anaesthesia in white Leghorn cockerels for typhlectomy

Thee different combinations of ketamine hydrochloride were used to induce general anaesthesia for surgical operations (typhlectomy) in 30 adult, single-comb White Leghorn cockerels. They were randomly divided into three groups, each comprising 10 birds. Birds in Group I received xylazine-ketamine combinations at the dose rate of 2 mg xylazine and 10 mg ketamine per kg i.v., whereas birds of Group II received diazepam (2.5 mg/kg i.v.) and 5 min later ketamine (75 mg/kg i.m.). In the Group III, midazolam (2 mg/kg i.m.) and 5 min later ketamine (50 mg/kg i.v.) was administered. The onset of sedation/anaesthesia was shortest (1.60 +/- 0.27 min) in Group I, followed by Group II (8.40 +/- 0.83 min) and Group III (17.10 +/- 1.71 min). Recovery period was shortest in the Group I (65-75 min) followed by Group II (80-85 min) and Group III (92-105 min). Sedation, muscle relaxation and surgical anaesthesia was optimal and excellent in Group I compared with the other two groups. Torticollis, salivation and dyspnoea were observed in Group III. Short-term limb contractions were present in all birds in Groups II and III, up to 20 min of observation. Recovery from anaesthesia was smooth in all three groups. A Surgical procedure (typhlectomy) was performed on all birds. Hypothermia was observed in Group II, whereas heart and respiratory depression was recorded in Group I. Blood sugar level did not vary significantly in any anaesthetic regime. The reduction of haemoglobin was maximum in Group II compared with Groups I and III. Hypoxaemia and hypercapnaea were elevated in all birds in Groups II and III. Blood electrolytes did not vary significantly from the baseline values among the three groups of birds during the period of observation (120 min). The xylazineketamine combination was found to be the best anaesthesia for surgical intervention in chickens.     

Effect of variable-dose propofol alone and in combination with two fixed doses of ketamine for total intravenous anesthesia in cats

OBJECTIVE: To determine the minimum infusion rate (MIR50) for propofol alone and in combination with ketamine required to attenuate reflexes commonly used in the assessment of anesthetic depth in cats. ANIMALS: 6 cats. PROCEDURE: Propofol infusion started at 0.05 to 0.1 mg/kg/min for propofol alone or 0.025 mg/kg/min for propofol and ketamine (low-dose ILD] constant rate infusion [CRI] of 23 microg/kg/min or high-dose [HD] CRI of 46 microg/kg/min), and after 15 minutes, responses of different reflexes were tested. Following a response, the propofol dose was increased by 0.05 mg/kg/min for propofol alone or 0.025 mg/kg/min for propofol and ketamine, and after 15 minutes, reflexes were retested. RESULTS: The MIR50 for propofol alone required to attenuate blinking in response to touching the medial canthus or eyelashes; swallowing in response to placement of a finger or laryngoscope in the pharynx; and to toe pinch, tetanus, and tail-clamp stimuli were determined. Addition of LD ketamine to propofol significantly decreased MIR50, compared with propofol alone, for medial canthus, eyelash, finger, toe pinch, and tetanus stimuli but did not change those for laryngoscope or tail-clamp stimuli. Addition of HD ketamine to propofol significantly decreased MIR50, compared with propofol alone, for medial canthus, eyelash, toe pinch, tetanus, and tail-clamp stimuli but did not change finger or laryngoscope responses. CONCLUSIONS AND CLINICAL RELEVANCE: Propofol alone or combined with ketamine may be used for total IV anesthesia in healthy cats at the infusion rates determined in this study for attenuation of specific reflex activity.     

Effect of diuretics on ketamine and sulfanilate elimination in cats

Rate constants of elimination were used to evaluate potential effects of diuretic agents on the elimination of ketamine from the blood of cats. Furosemide, mannitol, and aminophylline did not significantly alter the ketamine elimination rate constants, although the diuretics had a tendency to prolong elimination. This tendency of furosemide was further substantiated by observing the effect of furosemide on glomerular filtration. The rate of sulfanilate elimination, used as an indicator of glomerular filtration, was significantly decreased in the cats that were administered furosemide. Possible mechanisms for the influence of furosemide on the renal excretion of ketamine are discussed.     

Change in M-mode echocardiographic values in cats given ketamine

Determination was made of changes in heart rate and certain M-mode echocardiographic values in healthy cats given ketamine (3 to 5 mg/kg, IM). Heart rate and septal and left ventricular posterior wall thickness in diastole increased, and left ventricular internal diameter in diastole and shortening fraction decreased (P less than 0.02) after ketamine was given. With the adjustment for heart rate by analysis of covariance, left ventricular internal diameter in diastole, shortening fraction, and velocity of circumferential fiber shortening were significantly decreased (P less than 0.05) from base-line values.     

Duration of corneal anesthesia following topical administration of 0.5% proparacaine hydrochloride solution in clinically normal cats

OBJECTIVE: To determine duration of corneal anesthesia following topical administration of 0.5% proparacaine hydrochloride solution in domestic shorthair (DSH) cats. ANIMALS: 20 clinically normal DSH cats. PROCEDURES: Baseline corneal touch threshold (CCT) was established by use of a Cochet-Bonnet aesthesiometer. Treatment consisted of a single 50-microL topical application of an ophthalmic preparation of 0.5% proparacaine solution to a randomly selected eye of each cat. The corneal touch threshold was assessed 1 and 5 minutes after application to the cornea and at 5- minute intervals thereafter for 60 minutes. RESULTS: Corneal sensitivity, as determined by Cochet-Bonnet aesthesiometry, was significantly reduced from baseline for 25 minutes following topical administration of ophthalmic proparacaine. Maximal anesthetic effect lasted 5 minutes. CONCLUSIONS AND CLINICAL RELEVANCE: As determined by Cochet-Bonnet aesthesiometry, duration of anesthetic effects on the cornea induced by a single topical application of an ophthalmic preparation of 0.5% proparacaine solution in DSH cats is considerably shorter than the reported duration of corneal anesthesia in dogs.