Effects of saffan on cardiopulmonary function in healthy cats.

The effects of saffan on cardiopulmonary function were evaluated in eight healthy adult cats. Measured values were cardiac output by thermodilution, heart rate by electrocardiogram, arterial blood gases, respiratory rate and systolic, diastolic and mean arterial blood pressures by arterial catheterization. Calculated values included cardiac index, stroke volume and systemic vascular resistance. Statistical analysis employed paired t-tests comparing pre saffan anesthetic induction and post saffan anesthetic parameters over a 120 minute time sequence. Thirty min after saffan induction, significant depression in cardiac output was evident while stroke volume was significantly depressed at 45 and 60 min, systolic blood pressure at 15 min and respiratory rate at 5, 10 and 15 min. No significant changes occurred in cardiac index, heart rate, arterial blood gases, diastolic and mean arterial blood pressure or systemic vascular resistance. It was concluded that saffan causes significant depression of cardiopulmonary function in normal adult cats.     

Evaluation of a xylazine-ketamine hydrochloride combination in the cat.

Cardiopulmonary function was assessed in healthy cats given a xylazine-ketamine hydrochloride combination intramuscularly. Cardiac output, heart rate, stroke volume and cardiac index were significantly decreased. Systolic, diastolic and mean arterial blood pressure were also significantly decreased. Systemic vascular resistance and central venous pressure were significantly increased. Blood gas values remained stable. In conclusion, significant cardiovascular depression was noted in normal cats given the xylazine-ketamine combination at the dosages listed.     

Cardiopulmonary effects of a halothane/oxygen combination in healthy cats.

The effects of a halothane/oxygen combination on the cardiopulmonary function of 11 healthy cats were studied. Test parameters included cardiac output, measured via thermo-dilution, heart rate, respiratory rate, arterial blood pressure (systolic, diastolic and mean) and blood gas analysis. Values for systemic vascular resistance, cardiac index and stroke volume were calculated from these data. Cardiac output, cardiac index, heart rate, stroke volume, arterial blood pressure (systolic, diastolic and mean) and arterial blood pH were significantly decreased (p less than 0.001). Respiratory rate was also significantly decreased (p less than 0.007) with arterial CO2 tension being significantly increased (p less than 0.001). Statistically significant changes, where seen, persisted for the duration of the anesthetic period. Arterial O2 tension and systemic vascular resistance remained unchanged. All parameters returned to near pretest values within 30 minutes following cessation of halothane anesthesia.     

Cardiopulmonary effects of thiopental/lidocaine combination during anesthetic induction in the dog

The cardiopulmonary effects and tendencies to produce ventricular arrhythmias were evaluated in 13 dogs given a surgical plane of anesthesia by thiopental (IV) or a combination of thiopental and lidocaine (IV). Thiopental (22 mg/kg of body weight) was compared with a combination of thiopental (11 mg/kg) and lidocaine (8.8 mg/kg). Preanesthetic agents were not given. Both methods for IV anesthesia provided a smooth induction suitable for easy intubation. The thiopental/lidocaine combination had a shorter duration, produced no arrhythmias, and resulted in less cardiopulmonary depression than did thiopental alone. Bigeminy developed after intubation during 19 of 20 thiopental inductions as compared with that in 0 of 22 thiopental/lidocaine inductions. The bigeminies were preceded by systemic hypertension and tachycardia which developed as the trachea was being intubated. The increase in aortic pressure and heart rate was minimal after intubation during the thiopental/lidocaine inductions. Five minutes after administration of thiopental alone, increases in heart rate, aortic pressure, total peripheral vascular resistance, and left ventricular systolic and end-diastolic pressures were observed. When these increases in rate, preload, and afterload were considered in relation to a stabile maximum positive first derivative of left ventricular pressure, left ventricular contractility was considered to be decreased. Mild respiratory acidosis and hypoxemia were present at 5 and 10 minutes after thiopental induction. Because the combination of thiopental/lidocaine had less cardiopulmonary depressive effects and protected against arrhythmias, it would appear to be a good method for anesthetic induction of the patient with cardiopulmonary disease. In the patient with normal cardiopulmonary function, thiopental produces only a moderate and reversible depression.     

Cardiopulmonary effects of a ketamine/acepromazine combination in hypovolemic cats.

The cardiopulmonary effects of a ketamine/ acepromazine combination was studied in ten cats subjected to a 25% whole blood volume loss. Test parameters included cardiac output, measured via thermodilution, heart rate, respiratory rate, arterial blood pressure (systolic, diastolic and mean) and blood gas analysis. Values for cardiac index, stroke volume and systemic vascular resistance were calculated from these data. Posthemorrhage, cardiac output, cardiac index, stroke volume, heart rate and measurements of arterial blood pressure were significantly decreased (p less than 0.05). Following the induction of ketamine/ acepromazine anesthesia, cardiac output, cardiac index, stroke volume and heart rate showed mild but statistically insignificant declines and were above their respective posthemorrhage values 120 min into ketamine/ acepromazine anesthesia. Measurements of arterial blood pressure showed further declines from their respective posthemorrhage values that were statistically significant (p less than 0.05). Following hemorrhage, respiratory rate increased significantly (p less than 0.05), associated with a fall in arterial CO2 tension. During ketamine/ acepromazine anesthesia, respiratory rate showed a dramatic and significant decline (p less than 0.05) with arterial CO2 tension rising to prehemorrhage values. Systemic vascular resistance, arterial O2 tension and pH remained essentially unchanged throughout the experimental period.     

Echocardiographic evaluation of dogs receiving 1:1 thiopental/propofol in a clinical setting

The purpose of this study was to compare the echocardiographic Doppler blood pressure and heart rate effects of 1:1 thiopental/propofol with thiopental and propofol, when used as anesthesia‐induction agents. Seven healthy dogs (six Beagles and one Pembroke Welsh Corgi), ranging in age from 1 to 9 years and weighing 14.2 ± 2.4 kg (mean ± SD), were used during the study. In a cross‐over study design with a minimum drug interval of 3 days, each dog received propofol, thiopental, or a mixture of propofol–thiopental IV until each dog received all the three anesthetic agents. An initial dose (propofol 4.9 ± 0.8 mg kg^?1; thiopental 12.9 ± 2.4 mg kg^?1; propofol–thiopental 2.3 ± 0.3 mg kg^?1 (P)?5.7 ± 0.8 mg kg^?1 (T)) of each anesthetic agent was titrated IV until intubation was accomplished. Echocardiographic Doppler blood pressure and heart rate variables were recorded prior to anesthesia and at 1, 5, and 10 minutes after induction of anesthesia. anova and the Bonferroni's t‐test were used to evaluate the groups for differences. Alpha was <0.05. There was no significant effect of treatment on systolic or diastolic ventricular wall thickness, septal thickness, left atrial diameter, or systolic left ventricular diameter. There was a tendency for diastolic left ventricular diameter to decrease over time. There was a tendency for heart rate to increase with a significant difference at the 10‐minute time period between propofol (109 ± 26 beats minute^?1) and thiopental (129 ± 23 beats minute^?1). At the 10‐minute recording period, heart rate following the propofol/thiopental mixture (110 ± 34 beats minute^?1) was closer to that following propofol than to that following thiopental. With all induction agents, indirect blood pressure tended to decrease over time (p = 0.005); however, there was no difference between the groups. The changes observed were not considered to be of clinical significance. The propofol/thiopental mixture produces similar changes in echocardiographic variables when compared to propofol or thiopental, and could be substituted for propofol for induction of anesthesia in dogs.     

Hypertension in bulls and steers anesthetized with guaifenesin-thiobarbiturate-halothane combination

Eight bulls and steers (research animals) and 18 bulls (surgical patients) were anesthetized with guaifenesin and thiopental or thiamylal and for 90 minutes with halothane. Arterial blood pressure and heart rate were recorded in all animals. Cardiac output, plasma glucose and lactate concentrations, PCV, plasma proteins and plasma thromboxane B2 values were determined before (control) and every 15 minutes during anesthesia in the research animals. Plasma catecholamine concentrations were measured in 3 of the research animals and 3 of the surgical patients. Arterial pressure, heart rate, and plasma thromboxane B2 and catecholamine concentrations were also measured immediately after the trachea was intubated. All animals, except one, were hypertensive during anesthesia. Heart rate during anesthesia was significantly increased, compared with control measurements, and cardiac output was decreased. Plasma glucose and lactate values significantly increased when the animals were restrained on their sides. Plasma glucose concentrations remained increased during anesthesia, but lactate decreased. Packed cell volume and plasma proteins were unchanged by the induction of anesthesia. Plasma norepinephrine concentration was unchanged during anesthesia, and epinephrine concentration was decreased. Endotracheal intubation caused a transient significant increase in arterial pressure, heart rate, and thromboxane B2 and a nonsignificant increase in norepinephrine.     

Cardiopulmonary effects of halothane anesthesia in cats

The cardiopulmonary effects of 2 planes of halothane anesthesia (halothane end-tidal concentrations of 1.78% [light anesthesia] and 2.75% [deep anesthesia]) and 2 ventilatory modes (spontaneous ventilation [SV] or mechanically controlled ventilation [CV]) were studied in 8 cats. Anesthesia was induced and maintained with halothane in O2 only, and each cat was administered each treatment according to a Latin square design. Cardiac output, arterial blood pressure, pulmonary arterial pressure, heart rate, respiratory frequency, and PaO2, PaCO2, and pH were measured during each treatment. Stroke volume, cardiac index, and total peripheral resistance were calculated. A probability value of less than 5% was accepted as significant. In the cats, cardiac output, cardiac index, and stroke volume were reduced by deep anesthesia and CV, although only the reduction attributable to CV was significant. Systemic arterial pressure was significantly reduced by use of deep anesthesia and CV. Respiratory frequency was significantly lower during CV than during SV. Arterial PO2 was significantly decreased at the deeper plan of anesthesia, compared with the lighter plane. At the deeper plane of anesthesia, arterial PCO2 and pulmonary arterial pressure were significantly lower during CV than during SV. The deeper plane of halothane anesthesia depressed cardiopulmonary function in these cats, resulting in hypotension and considerable hypercapnia. Compared with SV, CV significantly reduced circulatory variables and should be used with care in cats. Arterial blood pressure was judged to be more useful for assessing anesthetic depth than was heart rate or respiratory frequency.     

Anesthetic interaction in cardiovascular research models: effects of xylazine and pentobarbital in cats

The effects of xylazine given to cats before anesthetization was induced with pentobarbital were determined. Cardiac hemodynamic variables and regional blood flow rates in the heart and other organs were measured, using radiolabeled microspheres. Two groups, each of 10 cats, were included in the study: one group (group 1) was anesthetized with pentobarbital given intraperitoneally and subsequently given xylazine; the other group (group 2) was first given 1 mg of xylazine/kg, IM, and then anesthetized with pentobarbital given IV. Anesthesia was maintained in both groups with nitrous oxide. The preanesthetic administration of xylazine decreased the amount of pentobarbital used for surgical anesthesia by approximately 50%. It also resulted in decreased heart rate, cardiac contractility, and cardiac output and increased left ventricular end-diastolic pressure, compared with those values in cats given pentobarbital (group 1). After the latter cats (anesthetized with pentobarbital) were given xylazine, heart rate, cardiac contractility, and cardiac output decreased and left ventricular end-diastolic pressure increased to values similar to those found in group 2 (given xylazine before anesthetization). Myocardial tissue blood flow rates in the left and right ventricles were lower in the cats of group 2. In group 1 cats, myocardial blood flow rates decreased when xylazine was subsequently added. Blood flow rates in the kidneys and gastrointestinal tract were generally decreased by xylazine. Xylazine profoundly changed cardiac hemodynamic function and perfusion in the heart, as well as several other organ systems, because of marked cardiodepression.     

Cardiopulmonary effects of a halothane/oxygen combination in hypovolemic cats.

The cardiopulmonary effects of a halothane/oxygen combination were studied in eight cats subjected to a 25% whole blood volume loss. Test parameters included cardiac output measured via thermodilution, heart rate, respiratory rate, arterial blood pressure (systolic, diastolic and mean) and blood gas analysis. Values for cardiac index, stroke volume and systemic vascular resistance were calculated from these data. Posthemorrhage cardiac output, cardiac index, stroke volume and measurements of arterial blood pressure were significantly decreased (p less than 0.05). Heart rate remained unchanged. Following induction of halothane anesthesia the above parameters experienced a further significant decline (p less than 0.05) from their immediate preanesthetic (i.e. posthemorrhage) values. Heart rate also significantly decreased (p less than 0.05). Thirty minutes following the cessation of halothane anesthesia these values returned to near-hemorrhage levels, being above their respective preanesthetic values. Systemic vascular resistance initially rose, peaking ten minutes into halothane anesthesia, before gradually falling to prehemorrhage values at the end of halothane anesthesia. Following hemorrhage, respiratory rate demonstrated a transient increase, associated with an arterial CO2 tension fall, before returning to initial values at the preanesthetic time. During halothane anesthesia respiratory rate remained unchanged whereas arterial CO2 tension rose significantly (p less than 0.05) and pH declined slightly from preanesthetic readings. These returned to prehemorrhage values 30 minutes following the cessation of halothane anesthesia.     

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.     

Cardiopulmonary effects of three different anaesthesia protocols in cats.

To develop an alternative anaesthetic regimen for cats with cardiomyopathy, the cardiopulmonary effects of three different premedication-induction protocols, followed by one hour maintenance with isoflurane in oxygen: air were evaluated in six cats. Group I: acepromazine (10 microg/kg) + buprenorphine (10 microg/kg) IM, etomidate (1-2 mg/kg) IV induction. Group II: midazolam (1 mg/kg) + ketamine (10 mg/kg) IM induction. Group III: medetomidine (1.5 mg/m2 body surface) IM, propofol (1-2 mg/kg) IV induction. Heart rate, arterial blood pressure, arterial blood gases, respiration rate, and temperature were recorded for the duration of the experiment. In group I the sedative effect after premedication was limited. In the other groups the level of sedation was sufficient. In all groups premedication resulted in a reduced blood pressure which decreased further immediately following induction. The reduction in mean arterial pressure (MAP) reached statistical significance in group I (142+/-22 to 81+/-14 mmHg) and group II (153+/-28 to 98+/-20 mmHg) but not in group III (165+/-24 to 134+/-29 mmHg). Despite the decrease in blood pressure, MAP was judged to have remained within an acceptable range in all groups. During maintenance of anaesthesia, heart rate decreased significantly in group III (from 165+/-24 to 125+/-10 b.p.m. at t=80 min). During anaesthesia the PCO2 and PO2 values increased significantly in all groups. On the basis of the results, the combination acepromazine-buprenorphine is preferred because heart rate, MAP, and respiration are acceptable, it has a limited sedative effect but recovery is smooth.     

Effects of changes in loading conditions and heart rate on the myocardial performance index in cats

OBJECTIVE: To evaluate the effect of changes in hemodynamics on the myocardial performance index (MPI) in cats. ANIMALS: 6 mixed-breed cats. PROCEDURES: Cats were anesthetized by administration of thiopental sodium; anesthesia was maintained by administration of isoflurane. Systolic arterial pressure and central venous pressure were measured by use of catheters, and heart rate was controlled by right atrial pacing. Afterload was increased by balloon occlusion of the descending aorta, and preload was increased by IV infusion of lactated Ringer's solution at a rate of 40 mL/kg/h. Echocardiography was performed for each condition. RESULTS: Atrial pacing significantly increased heart rate. The MPI did not change with heart rate. Arterial pressure and MPI increased significantly during aortic occlusion. The IV infusion increased fractional shortening but did not change the MPI. Multiple regression analysis revealed that the MPI was not affected by heart rate, systolic arterial pressure, central venous pressure, fractional shortening, or velocity of the E wave. CONCLUSIONS AND CLINICAL RELEVANCE: The MPI can be used to assess cardiac function in healthy cats. The MPI is independent of heart rate and systolic arterial pressure but is sensitive to changes in afterload.     

Diuretic effects of fenoldopam in healthy cats

Objective: To determine the effect of fenoldopam infusion on urine output, sodium excretion, creatinine clearance, and indirect blood pressure in healthy cats. Design: Prospective study. Setting: Veterinary medical teaching hospital. Animals: Eight purpose‐bred cats, 2–4 years old. Interventions: None. Measurements: Urine output was measured hourly for 12 hours before and after fenoldopam administration. Sodium excretion, modified creatinine clearance, and fractional sodium excretion were measured before and following fenoldopam administration. Urine specific gravity, central venous pressure, and systolic blood pressure were measured every 4 hours during the experiment. Main results: Compared with pre‐infusion values, urine output, sodium excretion, and fractional excretion of sodium increased significantly 6 hours after initiation of fenoldopam infusion. This increase was sustained throughout the observation period. The modified creatinine clearance decreased significantly following 2 hours of fenoldopam infusion, but increased significantly by 6 hours after infusion, the time of peak urine output. Changes in urine specific gravity mirrored changes in fractional sodium excretion, whereas the central venous pressure mirrored changes in modified creatinine clearance. The diuretic effect in cats was prevented when a dopamine receptor blocking agent was administered before fenoldopam infusion. Conclusion: Fenoldopam at a dose of 0.5 μg/kg/min induces diuresis in cats in a delayed manner. This increase appears to be due, in part, to dopamine receptor‐induced natriuresis. Changes in glomerular filtration rate may also occur.     

Anaesthetic and cardiopulmonary effects of intramuscular morphine, medetomidine and ketamine administered to telemetered cats

The quality and duration of anaesthesia, cardiorespiratory effects and recovery characteristics of a morphine, medetomidine, ketamine (MMK) drug combination were determined in cats. Six healthy, adult female cats were administered 0.2 mg/kg morphine sulphate, 60 microg/kg medetomidine hydrochloride, and 5 mg/kg ketamine hydrochloride intramuscularly. Atipamezole was administered intramuscularly at 120 min after MMK administration. Time to lateral recumbency, intubation, extubation and sternal recumbency were recorded. Cardiorespiratory variables and response to a noxious stimulus were recorded before and at 3 min and 10 min increments after drug administration until sternal recumbency. The time to lateral recumbency and intubation were 1.9+/-1.2 and 4.3+/-1.2 min, respectively. Body temperature and haemoglobin saturation with oxygen remained unchanged compared to baseline values throughout anaesthesia. Respiratory rate, tidal volume, minute volume, heart rate, and blood pressure were significantly decreased during anaesthesia compared to baseline values. One cat met criteria for hypotension (systolic blood pressure <90 mmHg). End tidal carbon dioxide increased during anaesthesia compared to baseline values. All but one cat remained non-responsive to noxious stimuli from 3 to 120 min. Time to extubation and sternal recumbency following atipamezole were 2.9+/-1.1 and 4.7+/-1.0 min, respectively. MMK drug combination produced excellent short-term anaesthesia and analgesia with minimal cardiopulmonary depression. Anaesthesia lasted for at least 120 min in all but one cat and was effectively reversed by atipamezole.     

Cardiopulmonary effects of using carbon dioxide for laparoscopic surgery in cats

The cardiopulmonary effects of capnoperitoneum were investigated in 8 spontaneously breathing, young adult female cats undergoing laparoscopic pancreatic biopsy (intra-abdominal pressure 12 mmHg). Cats were premedicated with acepromazine and hydromorphone, induced with ketamine and diazepam, and maintained using an end-tidal isoflurane concentration of 1.13% in 100% oxygen. Direct systemic arterial blood pressure, heart and respiratory rates, end-tidal carbon dioxide (CO(2)), and isoflurane were recorded every 5 min before insufflation (baseline), during insufflation of the abdomen with CO(2), and following desufflation. Arterial blood samples were drawn at baseline, at 10 and 30 min of insufflation, and 5 min after desufflation for blood gases. The significant findings (P < 0.05) were as follows: insufflation produced an increase in heart rate (5 to 15 min and at 30 min), mean arterial blood pressure (25 to 30 min), and diastolic arterial blood pressure (10 to 30 min). After desufflation, respiratory rate increased for 15 min. The changes were within physiologically acceptable limits in these healthy, anesthetized cats despite no artificial maintenance of minute ventilation.     

Renal hemodynamic and diuretic effects of low-dosage dopamine in anesthetized cats

Objective: To evaluate the effects of low‐dosage (3 μg/kg/min) dopamine on urine output, renal blood flow, creatinine clearance, sodium excretion, heart rate, and mean arterial pressure (MAP) in healthy anesthetized cats. Design: Controlled experimental study. Setting: University experimental laboratory. Animals: Twelve random‐bred 2–4‐year‐old cats. Interventions: Anesthesia, laparotomy for renal artery blood flow measurement, and arterial and venous catheterization. Measurements: Heart rate (HR), MAP, renal blood flow, urine output, sodium excretion, fractional sodium excretion, and creatinine clearance. Main results: No significant difference in urine output, sodium excretion, HR, or creatinine clearance occurred in cats receiving low‐dosage dopamine. A transient decrease in the mean arterial blood pressure occurred in cats receiving dopamine. Conclusions: Low‐dosage dopamine cannot be expected to induce diuresis in healthy cats. Low‐dosage dopamine may cause vasodilation in non‐renal vascular beds.     

Cardiopulmonary effects of anesthetic induction with thiopental, propofol, or a combination of ketamine hydrochloride and diazepam in dogs sedated with a combination of medetomidine and hydromorphone

OBJECTIVE: To evaluate the cardiopulmonary effects of anesthetic induction with thiopental, propofol, or ketamine hydrochloride and diazepam in dogs sedated with medetomidine and hydromorphone. ANIMALS: 6 healthy adult dogs. PROCEDURES: Dogs received 3 induction regimens in a randomized crossover study. Twenty minutes after sedation with medetomidine (10 microg/kg, IV) and hydromorphone (0.05 mg/kg, IV), anesthesia was induced with ketamine-diazepam, propofol, or thiopental and then maintained with isoflurane in oxygen. Measurements were obtained prior to sedation (baseline), 10 minutes after administration of preanesthetic medications, after induction before receiving oxygen, and after the start of isoflurane-oxygen administration. RESULTS: Doses required for induction were 1.25 mg of ketamine/kg with 0.0625 mg of diazepam/kg, 1 mg of propofol/kg, and 2.5 mg of thiopental/kg. After administration of preanesthetic medications, heart rate (HR), cardiac index, and PaO(2) values were significantly lower and mean arterial blood pressure, central venous pressure, and PaCO(2) values were significantly higher than baseline values for all regimens. After induction of anesthesia, compared with postsedation values, HR was greater for ketamine-diazepam and thiopental regimens, whereas PaCO(2) tension was greater and stroke index values were lower for all regimens. After induction, PaO(2) values were significantly lower and HR and cardiac index values significantly higher for the ketamine-diazepam regimen, compared with values for the propofol and thiopental regimens. CONCLUSIONS AND CLINICAL RELEVANCE: Medetomidine and hydromorphone caused dramatic hemodynamic alterations, and at the doses used, the 3 induction regimens did not induce important additional cardiovascular alterations. However, administration of supplemental oxygen is recommended.     

Intraosseous Cannulation and Drug Administration for Induction of Anesthesia in Chickens

Twenty-four chickens were randomly assigned to one of three treatments (ketamine, 30 mg/ kg; thiopental, 20 mg/kg; saline, 0.8 mL). Baseline data (heart rate, respiratory rate, systolic blood pressure, and cloacal temperature) were recorded before ulnar intraosseous cannulation and administration of drug treatment and for 30 minutes after administration. One investigator, unaware of the treatment administered, assessed the reaction to cannulation, number of attempts per cannulation, reaction to injection, time to induction and recovery, and quality of induction and recovery. Respiratory rate increased significantly (p < .05) from baseline after thiopental. Other parameters did not vary within groups or between groups. Most birds did not react or had a mild reaction to cannulation and injection, and on average fewer than two attempts were necessary. Quality of recovery was significantly (p < .05) better after thiopental. Time to recovery was significantly (p < .05) shorter after thiopental. No major histopathologic changes were noted in bone marrow samples from the injection site. This study demonstrates that the intraosseous route may be used to induce anesthesia in chickens, and that minimal changes in the variables studied were produced by ketamine and thiopental.     

Cardiovascular and respiratory effects of thiopental administration in hypovolemic dogs

The cardiopulmonary effects of thiopental sodium were studied in hypovolemic dogs from completion of until 1 hour after administration of the drug. Hypovolemia was induced by withdrawal of blood from dogs until mean arterial pressure of 60 mm of Hg was achieved. After stabilization at this pressure for 1 hour, 8 mg of thiopental/kg of body weight was administered IV to 7 dogs, and cardiopulmonary effects were measured. After blood withdrawal and prior to thiopental administration, heart rate and oxygen utilization ratio increased, whereas mean arterial pressure, mean pulmonary arterial pressure, central venous pressure, pulmonary wedge pressure, cardiac index, oxygen delivery, mixed venous oxygen tension, and mixed venous oxygen content decreased from baseline. Three minutes after thiopental administration, heart rate, mean arterial pressure, mean pulmonary arterial pressure, pulmonary vascular resistance, and mixed venous oxygen tension increased, whereas oxygen utilization ratio and arterial and mixed venous pH decreased from values measured prior to thiopental administration. Fifteen minutes after thiopental administration, heart rate was still increased; however by 60 minutes after thiopental administration, all measurements had returned to values similar to those obtained prior to thiopental administration.