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1.
OBJECTIVE: To determine the hemodynamic effects of nitrous oxide in isoflurane-anesthetized cats. ANIMALS: 12 healthy adult domestic shorthair cats. PROCEDURE: Cats were anesthetized by administration of isoflurane in oxygen. After instruments were inserted, end-tidal isoflurane concentration was set at 1.25 times the individual minimum alveolar concentration, and nitrous oxide was administered in a Latin-square design at 0, 30, 50, and 70%. Each concentration was administered for 25 minutes before measurements were obtained to allow for stabilization. Heart rate; systemic and pulmonary arterial pressures; central venous pressure; pulmonary artery occlusion pressure; cardiac output; body temperature; arterial and mixed-venous pH, PCO2, PO2, and hemoglobin concentrations; PCV; and total protein and lactate concentrations were measured before and during noxious stimulation for each nitrous oxide concentration. Arterial and mixed-venous bicarbonate concentrations and oxygen saturation, cardiac index, stroke index, rate-pressure product, systemic and pulmonary vascular resistance indices, left and right ventricular stroke work indices, arterial and mixed-venous oxygen contents, oxygen delivery, oxygen consumption, oxygen extraction ratio, alveolar-to-arterial oxygen difference, and venous admixture were calculated. RESULTS: Arterial pressure, central venous pressure, pulmonary arterial pressure, rate-pressure product, systemic and pulmonary vascular resistance indices, arterial PCO2, and PCV increased during administration of 70% nitrous oxide. Arterial and mixed-venous pH, mixed-venous PO2, and alveolar-to-arterial oxygen difference decreased during administration of 70% nitrous oxide. Results before and during noxious stimulation were similar. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of 70% nitrous oxide to isoflurane-anesthetized cats resulted in improved arterial pressure, which was related to a vasoconstrictive effect.  相似文献   

2.
Lidocaine dose‐dependently decreases the minimum alveolar concentration (MAC) of isoflurane in cats. The purpose of this study was to determine the hemodynamic effects of six lidocaine plasma concentrations in isoflurane anesthetized cats. Six cats were studied. After instrumentation, end‐tidal isoflurane concentration was set at 1.25 times the individual minimum alveolar concentration (MAC), which was determined in a previous study. Lidocaine was administered intravenously to target pseudo‐steady state plasma concentrations of 0, 3, 5, 7, 9, and 11 μg ml–1, and isoflurane concentration was reduced to an equipotent concentration, determined in a previous study. Cardiovascular variables; blood gases; PCV; total protein and lactate concentrations; and lidocaine and monoethylglycinexylidide concentrations were measured at each lidocaine target concentration, before and during noxious stimulation. Derived variables were calculated. Data were analyzed using a repeated measures anova , followed by a Tukey test for pairwise comparisons where appropriate. One cat was excluded from analysis because the study was aborted at 7 μg ml–1 due to severe cardiorespiratory depression. Heart rate, cardiac index, stroke index, right ventricular stroke work index, total protein concentration, mixed‐venous PO2 and hemoglobin oxygen saturation, arterial and mixed‐venous bicarbonate concentrations, and oxygen delivery were significantly lower during lidocaine administration than when no lidocaine was administered. Mean arterial pressure, central venous pressure, pulmonary artery pressure, systemic and pulmonary vascular resistance indices, PCV, arterial and mixed‐venous hemoglobin concentrations, lactate concentration, arterial oxygen concentration, and oxygen extraction ratio were significantly higher during administration of lidocaine than when no lidocaine was administered. Most changes were significant at lidocaine target plasma concentrations of 7 μg ml–1 and above. Noxious stimulation did not significantly affect most variables. Despite significantly decreasing in inhalant requirements, when combined with isoflurane, lidocaine produces greater cardiovascular depression than an equipotent dose of isoflurane alone. The use of lidocaine to reduce isoflurane requirements is not recommended in cats.  相似文献   

3.
ObjectiveTo characterize the hemodynamic effects of dexmedetomidine in isoflurane-anesthetized cats.Study designProspective experimental study.AnimalsSix healthy adult female cats weighing 4.6 ± 0.8 kg.MethodsDexmedetomidine was administered intravenously using target-controlled infusions to maintain nine plasma concentrations between 0 and 20 ng mL?1 in isoflurane-anesthetized cats. The isoflurane concentration was adjusted for each dexmedetomidine concentration to maintain the equivalent of 1.25 times the minimum alveolar concentration, based on a previous study. Heart rate, systemic and pulmonary arterial pressures, central venous pressure, pulmonary artery occlusion pressure, body temperature, and cardiac output were measured at each target plasma dexmedetomidine concentration. Additional variables were calculated. Arterial and mixed-venous blood samples were collected for blood gas, pH, and (on arterial blood only) electrolyte, glucose and lactate analysis. Plasma dexmedetomidine concentration was determined for each target. Pharmacodynamic models were fitted to the data.ResultsHeart rate, arterial pH, arterial bicarbonate concentration, mixed-venous PO2, mixed-venous pH, mixed-venous hemoglobin oxygen saturation, cardiac index, stroke index, and venous admixture decreased following dexmedetomidine administration. Arterial blood pressure, central venous pressure, pulmonary arterial pressure, pulmonary arterial occlusion pressure, packed cell volume, PaO2, PaCO2, arterial hemoglobin concentration, mixed-venous PCO2, mixed-venous hemoglobin concentration, ionized calcium concentration, glucose concentration, rate-pressure product, systemic and pulmonary vascular resistance indices, left ventricular stroke work index, arterial oxygen concentration, and oxygen extraction increased following dexmedetomidine administration. Most variables changed in a dexmedetomidine concentration-dependent manner.Conclusion and clinical relevanceThe use of dexmedetomidine as an anesthetic adjunct is expected to produce greater negative hemodynamic effects than a higher, equipotent concentration of isoflurane alone.  相似文献   

4.
OBJECTIVE: To determine hemodynamic effects of 3 concentrations of sevoflurane in cats. ANIMALS: 6 cats. PROCEDURE: Cats were anesthetized with sevoflurane in oxygen. After instruments were inserted, end-tidal sevoflurane concentration was set at 1.25, 1.5, or 1.75 times the individual minimum alveolar concentration (MAC), which was determined in another study. Twenty-five minutes were allowed after each change of concentration. Heart rate; systemic and pulmonary arterial pressures; central venous pressure; pulmonary artery occlusion pressure; cardiac output; body temperature; arterial and mixed-venous pH, PCO2, PO2, oxygen saturation, and hemoglobin concentrations; PCV; and total protein and lactate concentrations were measured for each sevoflurane concentration before and during noxious stimulation. Arterial and mixed-venous bicarbonate concentrations, cardiac index, stroke index, rate-pressure product, systemic and pulmonary vascular resistance indices, left and right ventricular stroke work indices, PaO2, mixed-venous partial pressure of oxygen (PVO2), oxygen delivery, oxygen consumption, oxygen-extraction ratio, alveolar-to-arterial oxygen difference, and venous admixture were calculated. Spontaneous and mechanical ventilations were studied during separate experiments. RESULTS: Mode of ventilation did not significantly influence any of the variables examined. Therefore, data from both ventilation modes were pooled for analysis. Mean arterial pressure, cardiac index, stroke index, rate-pressure product, left ventricular stroke work index, arterial and mixed-venous pH, PaO2, and oxygen delivery decreased, whereas PaCO2, PVO2, and mixed-venous partial pressure of CO2 increased significantly with increasing doses of sevoflurane. Noxious stimulation caused a significant increase in most cardiovascular variables. CONCLUSIONS AND CLINICAL RELEVANCE: Sevoflurane induces dose-dependent cardiovascular depression in cats that is mainly attributable to myocardial depression.  相似文献   

5.
OBJECTIVE: To characterize the effects of ketamine administration on the cardiovascular and respiratory systems and on acid-base balance and to record adverse effects of ketamine in isoflurane-anesthetized dogs. ANIMALS: 6 healthy adult mongrel dogs. PROCEDURE: Dogs were anesthetized with isoflurane (1.25 times the individual minimum alveolar concentration) in oxygen, and ketamine was administered IV to target pseudo-steady-state plasma concentrations of 0, 0.5, 1, 2, 5, 8, and 11 microg/mL. Isoflurane concentration was reduced to an equipotent concentration. Cardiovascular, respiratory, and acid-base variables; body temperature; urine production; and adverse effects were recorded before and during noxious stimulation. Cardiac index, stroke index, rate-pressure product, systemic vascular resistance index, pulmonary vascular resistance index, left ventricular stroke work index, right ventricular stroke work index, arterial oxygen concentration, mixed-venous oxygen concentration, oxygen delivery, oxygen consumption, oxygen extraction ratio, alveolar-arterial oxygen partial pressure gradient, and venous admixture were calculated. Plasma ketamine and norketamine concentrations were measured. RESULTS: Overall, ketamine administration improved ventilation, oxygenation, hemodynamics, and oxygen delivery in isoflurane-anesthetized dogs in a dosedependent manner. With the addition of ketamine, core body temperature was maintained or increased and urine production was maintained at an acceptable amount. However, at the higher plasma ketamine concentrations, adverse effects such as spontaneous movement and profuse salivation were observed. Myoclonus and dysphoria were observed during recovery in most dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Infusion of ketamine appears to be a suitable technique for balanced anesthesia with isoflurane in dogs. Plasma ketamine concentrations between 2 to 3 microg/mL elicited the most benefits with minimal adverse effects.  相似文献   

6.
Alterations in parasympathetic tone are partially responsible for xylazine's hemodynamic effects. The purpose of this study was to evaluate and compare the hemodynamic changes caused by the administration of intravenous (IV) atropine or glycopyrrolate after IV xylazine in isoflurane-anesthetized dogs. Six healthy beagles (8.2 to 10.7 kg) were used in two trials separated by 7 days. Anesthesia was induced and maintained with isoflurane in 100% oxygen with controlled ventilation. Once constant end-tidal isoflurane (1.8%) and arterial partial pressure of carbon dioxide (35 to 45 mm Hg) values were reached, baseline data were recorded and xylazine (0.5 mg/kg, IV) was given. In trial 1 atropine (0.1 mg/kg, IV) was given 5 minutes after xylazine, and in trial 2 glycopyrrolate (0.025, mg/kg, IV), was given 5 minutes after xylazine. Hemodynamic variables were recorded 3 minutes after xylazine and 3 minutes after anticholinergic administration. In trial 2, bilateral vagotomies were performed 10 minutes after glycopyrrolate, and hemodynamic variables were recorded 3 minutes later. Heart rate, cardiac index, and stroke index decreased; arterial pressure and systemic vascular resistance increased after xylazine. Heart rate, cardiac index, and rate pressure product increased after anticholinergic administration. Significant differences between atropine and glycopyrrolate were not observed in any of the hemodynamic parameters. Similarly, significant differences between glycopyrrolate and bilateral vagotomy were not observed. The authors conclude that intravenous atropine and glycopyrrolate have equivalent hemodynamic actions during the increased pressure phase after IV xylazine in isoflurane-anesthetized dogs; that intravenous atropine and glycopyrrolate produce comparable increases in heart rate and that both may increase the risk of myocardial hypoxia associated with an increase in rate pressure product; and that vagal blockade produced by high-dose glycopyrrolate (.025 mg/kg, IV) is similar to that produced by bilateral vagotomy.  相似文献   

7.
OBJECTIVE: To evaluate the effect of intratesticular administration of lidocaine on cardiovascular responses and cremaster muscle tension during castration of isoflurane-anesthetized stallions. ANIMALS: 28 healthy stallions (mean +/- SD age, 4.2 +/- 2.8 years) with no testicular abnormalities that were scheduled for castration. PROCEDURE: Each horse was given acepromazine (20 microg/kg, IM), romifidine (50 microg/kg, IV), and butorphanol (20 microg/kg, IV). Anesthesia was induced with ketamine (2.5 mg/kg, IV) and midazolam (50 microg/kg, IV) and maintained with isoflurane (1.7% end-tidal concentration). After 10 minutes at a stable anesthetic plane, a needle was placed in each testicle and either no fluid or 15 mL of 2% lidocaine was injected; 10 minutes after needle placement, surgery was commenced. Pulse rate and arterial blood pressures were measured invasively at intervals from 5 minutes prior to castration (baseline) until 5 minutes after the left spermatic cord was clamped. The surgeon subjectively scored the degree of cremaster muscle tension. In 2 horses, lidocaine labeled with radioactive carbon (C(14)) was used and testicular autoradiograms were obtained. RESULTS: Compared with baseline values, castration significantly increased blood pressure measurements; intratesticular injection of lidocaine decreased this blood pressure response and cremaster muscle tension. In 2 horses, autoradiography revealed diffuse distribution of lidocaine into the spermatic cord but poor distribution into the cremaster muscle. CONCLUSIONS AND CLINICAL RELEVANCE: In isoflurane-anesthetized stallions, intratesticular injection of lidocaine prior to castration appeared to decrease intraoperative blood pressure responses and cremaster muscle tension and may be a beneficial supplement to isoflurane anesthesia.  相似文献   

8.
Sevoflurane has recently been introduced in feline anesthesia. However, its cardiovascular effects have not, to our knowledge, been reported in this species. Six healthy cats, aged 1.81 ± 0.31 years (mean ± SEM) and weighing 3.47 ± 0.11 kg, were studied. Anesthesia was induced and maintained with sevoflurane in oxygen. Body temperature was maintained between 38.5 and 39.55 °C. After instrumentation, end‐tidal sevoflurane concentration was randomly set at 1.25, 1.5, and 1.75 times the individual minimum alveolar concentration (MAC), determined in a previous study, according to a Latin Square Design. Thirty minutes of stabilization was allowed after each change of concentration. ECG and heart rate, systemic and pulmonary arterial pressures, central venous pressure (CVP), and core body temperature were continuously monitored and recorded. Inspired and end‐tidal oxygen, carbon dioxide, and sevoflurane concentrations were measured using a Raman spectrometer, calibrated every 80 minutes with three calibration gases of known sevoflurane concentration (1, 2, and 5%). Moreover, at selected times, pulmonary artery occlusion pressure and cardiac output (thermodilution) were measured, and arterial and mixed venous blood samples were collected for pH and blood gas analysis, hemoglobin concentration, hemoglobin oxygen saturation, packed cell volume (PCV) and total protein determination, and lactate concentration measurement. Cardiac index (CI), stroke index (SI), systemic and pulmonary vascular resistance indices, rate‐pressure product, left and right ventricular stroke work indices (LVSWI and RVSWI, respectively), arterial and mixed venous oxygen contents, oxygen delivery, oxygen consumption, and oxygen utilization ratio were calculated. Data were analyzed by a Repeated Measure Latin Square Design followed by a Tukey's test for 2 × 2 comparisons. Arterial pH significantly decreased from 7.40 ± 0.05 to 7.29 ± 0.07 with the administration of increasing concentrations of sevoflurane. Similarly, LVSWI decreased from 3.72 ± 0.60 to 2.60 ± 0.46 g m?2. Mean arterial pressure, PaO2, mixed venous pH, CI, SI, and oxygen delivery tended to decrease dose‐dependently, whereas CVP, PaCO2, Pv CO2, PCV, and arterial and mixed venous hemoglobin concentrations tended to increase dose‐dependently with the administration of sevoflurane. However, these trends did not reach statistical significance, possibly because of the limited number of animals studied. Sevoflurane seemed to induce dose‐dependent cardiovascular depression in cats.  相似文献   

9.
ObjectiveTo determine the dose of phenylephrine, norepinephrine and dopamine necessary to maintain mean arterial pressure (MAP) within 70–80 mmHg during administration of isoflurane, isoflurane and vatinoxan and isoflurane, vatinoxan and dexmedetomidine at three plasma concentrations.Study designRandomized crossover experimental study.AnimalsA group of five adult healthy neutered male cats.MethodsInstrumentation occurred during anesthesia with isoflurane in oxygen. Isoflurane end-tidal concentration was set to 1.25 × minimum alveolar concentration (MAC). Phenylephrine, norepinephrine or dopamine was administered to maintain MAP 70–80 mmHg. A target-controlled infusion system was used to administer vatinoxan at a target plasma concentration of 1 μg mL–1 and three dexmedetomidine concentrations (5, 10 and 20 ng mL–1). Isoflurane concentration was altered to maintain an equivalent 1.25 MAC. Heart rate, arterial blood pressure, central venous pressure, pulmonary artery pressure, pulmonary artery occlusion pressure, body temperature, arterial and mixed venous blood gas, cardiac output and drug concentrations were measured at baseline (isoflurane alone), during vatinoxan administration, and during administration of vatinoxan and dexmedetomidine at the three target concentrations.ResultsMAP < 70 mmHg was observed with vatinoxan alone and in the dopamine treatment with dexmedetomidine concentrations ≤ 10 ng mL–1. Norepinephrine and phenylephrine maintained MAP 70–80 mmHg during vatinoxan and dexmedetomidine ≤ 10 ng mL–1. As the target dexmedetomidine concentration increased, the dose of norepinephrine and phenylephrine needed to maintain MAP 70–80 mmHg decreased; no treatment was necessary to maintain MAP > 70 mmHg at the 20 ng mL–1 target dexmedetomidine concentration in most cats.Conclusions and clinical relevanceNorepinephrine and phenylephrine, but not dopamine, are effective to prevent hypotension in isoflurane-anesthetized cats administered dexmedetomidine and vatinoxan.  相似文献   

10.
OBJECTIVE: To describe the pharmacokinetics of lidocaine and its active metabolite, monoethylglycinexylidide (MEGX), after i.v. administration of a single bolus of lidocaine in cats that were awake in phase 1 and anesthetized with isoflurane in phase 2 of the study. ANIMALS: 8 healthy adult cats. PROCEDURE: During phase 1, cats were administered lidocaine (2 mg/kg, i.v.) as a bolus injection (time 0). During phase 2, cats were anesthetized with isoflurane and maintained at 0.75 times the minimum alveolar concentration of isoflurane for each specific cat. After a 15-minute equilibration period, lidocaine (2 mg/kg, i.v.) was administered as a bolus injection to each cat (time 0). In both phases, plasma concentrations of lidocaine and MEGX were measured at various time points by use of liquid chromatography-mass spectrometry. RESULTS: Anesthesia with isoflurane significantly decreased the volume of the central compartment, clearance, and elimination half-life of lidocaine and significantly increased the extrapolated plasma drug concentration at time 0, compared with values for awake cats. Pharmacokinetics of MEGX were also changed by isoflurane-induced anesthesia because the maximum observed plasma concentration (C(max)), area under the concentration-time curve extrapolated to infinity, and time to C(max) were significantly higher in anesthetized cats, compared with values for awake cats. CONCLUSIONS AND CLINICAL RELEVANCE: Pharmacokinetics of lidocaine and MEGX were substantially altered in cats anesthetized by use of isoflurane. When pharmacokinetic variables are used to determine loading and infusion doses in awake or anesthetized cats, they should be measured in cats that are awake or anesthetized, respectively.  相似文献   

11.
OBJECTIVE: To determine the effect of IV administration of perzinfotel on the minimum alveolar concentration (MAC) of isoflurane in dogs. Animals-6 healthy sexually intact male Beagles. PROCEDURES: Dogs were instrumented with a telemetry device that permitted continuous monitoring of heart rate, arterial blood pressure, and body temperature. Dogs were anesthetized with propofol (4 to 6 mg/kg, IV) and isoflurane for 30 minutes before determination of MAC of isoflurane. Isoflurane MAC values were determined 4 times, separated by a minimum of 7 days, before and after IV administration of perzinfotel (0 [control], 5, 10, and 20 mg/kg). Bispectral index and percentage hemoglobin saturation with oxygen (SpO(2)) were monitored throughout anesthesia. RESULTS: Isoflurane MAC was 1.32 +/- 0.14%. Intravenous administration of perzinfotel at 0, 5, 10, and 20 mg/kg decreased isoflurane MAC by 0%, 24%, 30%, and 47%, respectively. Perzinfotel significantly decreased isoflurane MAC values, compared with baseline and control values. The bispectral index typically increased with higher doses of perzinfotel and lower isoflurane concentrations, but not significantly. Heart rate, body temperature, and SpO(2) did not change, but systolic, mean, and diastolic arterial blood pressures significantly increased with decreases in isoflurane MAC after administration of perzinfotel at 10 and 20 mg/kg, compared with 0 and 5 mg/kg. CONCLUSIONS AND CLINICAL RELEVANCE: IV administration of perzinfotel decreased isoflurane MAC values. Improved hemodynamics were associated with decreases in isoflurane concentration.  相似文献   

12.
The objective of this study was to determine the effects of the administration of a high volume of isotonic crystalloid at a rapid rate on cardiovascular function in normovolemic, isoflurane-anesthetized dogs during induced hypotension.Using a prospective study, 6 adult dogs were induced to general anesthesia and cardiovascular and hematological values were measured while the dogs were maintained at 3 hemodynamic states: first during light anesthesia with 1.3% end-tidal isoflurane (ETI); then during a hypotensive state induced by deep anesthesia with 3% ETI for 45 min while administered 1 mL/kg body weight (BW) per minute of isotonic fluids; and then decreased to 1.6% ETI while receiving 1 mL/kg BW per minute of fluids for 15 min. End-tidal isoflurane (ETI) at 3.0 ± 0.2% decreased arterial blood pressure (ABP), cardiac index (CI), and stroke volume index (SVI), and increased stroke volume variation (SVV) and central venous pressure (CVP). Fluid administration during 3% ETI decreased only SVV and systemic vascular resistance index (SVRI), while CVP increased progressively. Decreasing ETI to 1.6 ± 0.1% returned ABP and SVI to baseline (ETI 1.3 ± 0.1%), while CI and heart rate increased and SVV decreased. There was significant progressive clinical hemodilution of hemoglobin (Hb), packed cell volume (PCV), total protein (TP), colloid osmotic pressure (COP), arterial oxygen content (CaO2), and central-venous oxygen content (CcvO2).High-volume, rapid-rate administration of an isotonic crystalloid was ineffective in counteracting isoflurane-induced hypotension in normovolemic dogs at a deep plane of anesthesia. Cardiovascular function improved only when anesthetic depth was reduced. Excessive hemodilution and its adverse consequences should be considered when a high volume of crystalloid is administered at a rapid rate.  相似文献   

13.
OBJECTIVE: To determine the cardiopulmonary effects of increasing doses of dopamine, dobutamine, epinephrine, and phenylephrine and measure plasma concentrations of norepinephrine, epinephrine, and dopamine in cats anesthetized with isoflurane. ANIMALS: 6 healthy adult cats. PROCEDURES: Each cat was anesthetized with isoflurane (1.5 X minimum alveolar concentration) on 4 occasions. Cardiopulmonary measurements were obtained after a 30-minute stabilization period; 20 minutes after the start of each infusion dose; and 30, 60, and 90 minutes after the infusion was discontinued. Cats received 5 progressively increasing infusions of epinephrine or phenylephrine (0.125, 0.25, 0.5, 1, and 2 microg/kg/min) or dobutamine or dopamine (2.5, 5, 10, 15, and 20 microg/kg/min). The order of treatment was randomly allocated. Results-All 4 treatments increased oxygen delivery. Heart rate (HR) increased during administration of all drugs except phenylephrine, and mean arterial pressure increased during administration of all drugs except dobutamine. A progressive metabolic acidosis was detected, but whole-blood lactate concentration only increased during administration of epinephrine and dobutamine. Systemic vascular resistance index increased during administration of phenylephrine, decreased during administration of dobutamine, and remained unchanged during administration of dopamine and epinephrine. A positive inotropic effect was detected with all treatments. CONCLUSIONS AND CLINICAL RELEVANCE: During anesthesia in cats, administration of dopamine, dobutamine, and epinephrine may be useful for increasing cardiac output, with dopamine having the most useful effects. Administration of phenylephrine increased cardiac and systemic vascular resistance indexes with minimal effect on HR and may be useful for increasing mean arterial pressure without increasing HR.  相似文献   

14.
OBJECTIVE: To determine plasma disposition after dermal application of a liposome-encapsulated formulation of lidocaine in cats. ANIMALS: 6 healthy adult cats with a mean (+/- SD) body weight of 4.1 +/- 0.44 kg. PROCEDURE: CBC determination and biochemical analysis of blood samples were performed for all cats. Cats were anesthetized by use of isoflurane, and catheters were placed IV in a central vein. The next day, blood samples were obtained from the catheters before and 1, 2, 3, 4, 6, 8, 10, 12, and 24 hours after applying a 4% liposome-encapsulated lidocaine cream (15 mg/kg) to a clipped area over the cephalic vein. Plasma concentrations of lidocaine were analyzed with a high-performance liquid chromatography assay. Results-Two cats had minimal transdermal absorption of lidocaine, with lidocaine concentrations below the sensitivity of the assay at all but 1 or 2 time points. In the other 4 cats, the median maximum plasma concentration was 149.5 ng/ml, the median time to maximum plasma concentration was 2 hours, and the median area under the concentration versus time curve from zero to infinity was 1014.5 ng.h/ml. CONCLUSIONS AND CLINICAL RELEVANCE: Maximum plasma concentrations of lidocaine remained substantially below toxic plasma concentrations for cats. On the basis of these data, topical administration of a liposome-encapsulated lidocaine formulation at a dose of 15 mg/kg appears to be safe for use in healthy adult cats.  相似文献   

15.
OBJECTIVE: To assess physiologic responses and plasma endothelin (ET)-1 concentrations associated with abrupt cessation of nitric oxide (NO) inhalation in isoflurane-anesthetized horses. ANIMALS: 6 healthy adult Standardbreds. PROCEDURES: Horses were anesthetized with isoflurane in oxygen and placed in dorsal recumbency. Nitric oxide was pulsed into the respiratory tract for 2.5 hours, and then administration was abruptly discontinued. Just prior to commencement and at cessation of NO administration, and at intervals during a 30-minute period following cessation of NO inhalation, several variables including PaO(2), mean pulmonary artery pressure, venous admixture or pulmonary shunt fraction (Qs/Qt), and plasma ET-1 concentration were recorded or calculated. RESULTS: After cessation of NO inhalation, PaO(2) decreased slowly but significantly (172.7 +/- 29.8 mm Hg to 84.6 +/- 10.9 mm Hg) and Qs/Qt increased slowly but significantly (25 +/- 2% to 40 +/- 3%) over a 30-minute period. Mean pulmonary artery pressure increased slightly (14.0 +/- 1.3 mm Hg to 16.8 +/- 1 mm Hg) over the same time period. No change in serum ET-1 concentration was detected, and other variables did not change or underwent minor changes. CONCLUSIONS AND CLINICAL RELEVANCE: The improvement in arterial oxygenation during pulsed inhalation of NO to healthy isoflurane-anesthetized horses decreased only gradually during a 30-minute period following cessation of NO inhalation, and serum ET-1 concentration was not affected. Because a rapid rebound response did not develop, inhalation of NO might be clinically useful in the treatment of hypoxemia in healthy isoflurane-anesthetized horses.  相似文献   

16.
OBJECTIVE: To evaluate the effects of acepromazine maleate on the cardiovascular changes induced by dopamine in isoflurane-anesthetized dogs. STUDY DESIGN: Prospective, randomized cross-over experimental design. ANIMALS: Six healthy adult spayed female dogs weighing 16.4 +/- 3.5 kg (mean +/- SD). METHODS: Each dog received two treatments, at least 1 week apart. Acepromazine (0.03 mg kg(-1), IV) was administered 15 minutes before anesthesia was induced with propofol (7 mg kg(-1), IV) and maintained with isoflurane (1.8% end-tidal). Acepromazine was not administered in the control treatment. Baseline cardiopulmonary parameters were measured 90 minutes after induction. Thereafter, dopamine was administered intravenously at 5, 10, and 15 microg kg(-1) minute(-1), with each infusion rate lasting 30 minutes. Cardiopulmonary data were obtained at the end of each infusion rate. RESULTS: Dopamine induced dose-related increases in cardiac index (CI), stroke index, arterial blood pressure, mean pulmonary arterial pressure, oxygen delivery index (DO(2)I) and oxygen consumption index. In the control treatment, systemic vascular resistance index (SVRI) decreased during administration of 5 and 10 microg kg(-1) minute(-1) of dopamine and returned to baseline with the highest dose (15 microg kg (-1) minute(-1)). After acepromazine treatment, SVRI decreased from baseline during dopamine administration, regardless of the infusion rate, and this resulted in a smaller increase in blood pressure at 15 microg kg (-1) minute(-1). During dopamine infusion hemoglobin concentrations were lower following acepromazine and this contributed to significantly lower arterial O(2) content. CONCLUSIONS: Acepromazine prevented the return in SVRI to baseline and reduced the magnitude of the increase in arterial pressure induced by higher doses of dopamine. However, reduced SRVI associated with lower doses of dopamine and the ability of dopamine to increase CI and DO(2)I were not modified by acepromazine premedication. CLINICAL RELEVANCE: Previous acepromazine administration reduces the efficacy of dopamine as a vasopressor agent in isoflurane anesthetized dogs. Other beneficial effects of dopamine such as increased CO are not modified by acepromazine.  相似文献   

17.
ObjectiveTo assess the effect of two intravenous (IV) doses of lidocaine on the minimum anesthetic concentration (MAC) of isoflurane in chickens.Study designBlinded, prospective, randomized, experimental crossover study.AnimalsA total of six adult female chickens weighing 1.90 ± 0.15 kg.MethodsChickens were anesthetized with isoflurane and mechanically ventilated. Isoflurane MAC values were determined (T0) in duplicate using an electrical noxious stimulus and the bracketing method. After MAC determination, a low dose (LD; 3 mg kg–1 followed by 3 mg kg–1 hour–1) or high dose (HD; 6 mg kg?1 followed by 6 mg kg?1 hour–1) of lidocaine was administered IV. MAC determination was repeated at 1.5 (T1.5) and 3 (T3) hours of lidocaine administration and blood was collected for analysis of plasma lidocaine and monoethylglycinexylidide (MEGX) concentrations. Pulse rate, peripheral hemoglobin oxygen saturation, noninvasive systolic arterial pressure and cloacal temperature were recorded at T0, T1.5 and T3. Treatments were separated by 1 week. Data were analyzed using mixed-effects model for repeated measures.ResultsMAC of isoflurane (mean ± standard deviation) at T0 was 1.47 ± 0.18%. MAC at T1.5 and T3 was 1.32 ± 0.27% and 1.26 ± 0.09% (treatment LD); and 1.28 ± 0.06% and 1.30 ± 0.06% (treatment HD). There were no significant differences between treatments or times. Maximum plasma lidocaine concentrations at T3 were 496 ± 98 and 1200 ± 286 ng mL–1 for treatments LD and HD, respectively, and were not significantly different from T1.5. With treatment HD, plasma concentration of MEGX was significantly higher at T3 than at T1.5. Physiological variables were not significantly different among times with either treatment.Conclusions and clinical relevanceAdministration of lidocaine did not significantly change isoflurane MAC in chickens. Within treatments, plasma lidocaine concentrations were not significantly different at 1.5 and 3 hours.  相似文献   

18.
OBJECTIVE: To measure cardiac output and other hemodynamic variables in anesthetized dogs undergoing laparotomy because of abdominal neoplasia. DESIGN: Prospective case series. ANIMALS: 8 dogs with splenic or hepatic tumors. PROCEDURES: Dogs were anesthetized and underwent abdominal laparotomy. End-tidal isoflurane concentration, heart rate, arterial blood pressures, cardiac output, arterial pH, blood gas partial pressures, PCV, and plasma total protein concentration were measured at set intervals before, during, and after surgery. Cardiac index, stroke index, and systemic vascular resistance index were calculated. RESULTS: End-tidal isoflurane concentration was lowest before and after surgery. Heart rate did not change significantly throughout the anesthetic period. Arterial blood pressures and systemic vascular resistance index were highest shortly after surgery began; cardiac index and stroke volume index did not change significantly during surgery but increased significantly after surgery ended. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that in dogs undergoing laparotomy because of abdominal neoplasia, changes in arterial blood pressures were not necessarily indicative of qualitatively similar changes in cardiac index.  相似文献   

19.
OBJECTIVE: To evaluate the cardiovascular effects of the alpha2-adrenergic receptor agonist medetomidine hydrochloride in clinically normal cats. ANIMALS: 7 clinically normal cats. PROCEDURE: Cats were anesthetized with isoflurane, and thermodilution catheters were placed for measurement of central venous, pulmonary, and pulmonary capillary wedge pressures and for determination of cardiac output. The dorsal pedal artery was catheterized for measurement of arterial blood pressures and blood gas tensions. Baseline variables were recorded, and medetomidine (20 microg/kg of body weight, IM) was administered. Hemodynamic measurements were repeated 15 and 30 minutes after medetomidine administration. RESULTS: Heart rate, cardiac index, stroke index, rate-pressure product, and right and left ventricular stroke work index significantly decreased from baseline after medetomidine administration, whereas systemic vascular resistance and central venous pressure increased. However, systolic, mean, and diastolic arterial pressures as well as arterial pH, and oxygen and carbon dioxide tensions were not significantly different from baseline values. CONCLUSIONS AND CLINICAL RELEVANCE: When administered alone to clinically normal cats, medetomidine (20 microg/kg, IM) induced a significant decrease in cardiac output, stroke volume, and heart rate. Arterial blood pressures did not increase, which may reflect a predominant central alpha2-adrenergic effect over peripheral vascular effects.  相似文献   

20.
OBJECTIVE: To determine the effects of IV administration of lidocaine on thermal antinociception in conscious cats. ANIMALS: 6 cats. PROCEDURE: 2 experiments were performed in each cat (interval of at least 2 months). In experiment 1, lidocaine pharmacokinetics were determined for each conscious cat following IV administration of a bolus of lidocaine (2 mg/kg). In experiment 2, data from experiment 1 were used to calculate appropriate doses of lidocaine that would achieve predetermined plasma lidocaine concentrations in the cats; lidocaine (or an equivalent volume of saline [0.9% NaCl] solution as the control treatment) was administered IV to target pseudo-steady-state plasma concentrations of 0, 0.5, 1, 2, 5, and 8 microg/mL. Skin temperature and thermal threshold were determined at the start of the experiment (baseline) and at each concentration. Samples of venous blood were obtained at each target concentration for plasma lidocaine concentration determination. RESULTS: In experiment 2, actual plasma lidocaine concentrations were 0.00 +/- 0.00 microg/mL, 0.25 +/- 0.18 microg/mL, 0.57 +/- 0.20 microg/mL, 1.39 +/- 0.13 microg/mL, 2.33 +/- 0.45 microg/mL, and 4.32 +/- 0.66 microg/mL for target plasma concentrations of 0, 0.5, 1, 2, 5, and 8 microg/mL, respectively. Compared with baseline values, no significant change in skin temperature or thermal threshold was detected at any lidocaine plasma concentration (or saline solution equivalent). Skin temperature or thermal threshold values did not differ between lidocaine or control treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that these moderate plasma concentrations of lidocaine did not affect thermal antinociception in cats.  相似文献   

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