Search Results

Abstract

Objective—To determine the effects of IV administration of perzinfotel and a perzinfotel-fentanyl combination on the minimum alveolar concentration (MAC) of isoflurane in dogs.

Animals—6 healthy sexually intact Beagles (3 males and 3 females).

Procedures—All dogs were instrumented with a telemetry device for continuous monitoring of heart rate, arterial blood pressure, and core body temperature (at a femoral artery). Dogs were anesthetized with propofol (6 mg/kg, IV) and isoflurane. Isoflurane MAC values were determined in 3 experiments in each dog, separated by at least 7 days, before (baseline) and after the following treatments: no treatment (anesthetic only), perzinfotel (20 mg/kg, IV), fentanyl (5 μg/kg bolus, IV, followed by a continuous IV infusion at 0.15 μg/kg/min), and a fentanyl-perzinfotel combination (20 mg of perzinfotel/kg, IV, plus the fentanyl infusion). Bispectral index and oxygen saturation as measured by pulse oximetry were also monitored throughout anesthesia.

Results—Without treatment, the mean ± SD isoflurane MAC for all 6 dogs was 1.41 ± 0.10%. Baseline MAC was 1.42 ± 0.08%. Intravenous administration of perzinfotel, fentanyl, and the perzinfotel-fentanyl combination significantly decreased the MAC by 39%, 35%, and 66%, respectively. Perzinfotel and perzinfotel-fentanyl administration yielded significant increases in the bispectral index. Mean, systolic, and diastolic arterial blood pressures significantly increased from baseline values when perzinfotel was administered. Systolic arterial blood pressure significantly increased from the baseline value when perzinfotel-fentanyl was administered. No adverse effects were detected.

Conclusions and Clinical Relevance—IV administration of perzinfotel, fentanyl, or a perzinfotel-fentanyl combination reduced isoflurane MAC in dogs and increased arterial blood pressure.

Abstract

OBJECTIVE To establish a study cutoff for evidence of glaucoma on the basis of IOP measurements from a large population of healthy dogs and to assess the effects of IV propofol administration on IOPs in premedicated and nonpremedicated dogs with and without glaucoma defined by this method.

DESIGN Prospective, descriptive study.

ANIMALS 234 client-owned dogs.

PROCEDURES IOPs measured in 113 healthy dogs (226 eyes) were used to calculate an IOP value indicative of glaucoma. The IOPs were measured in an additional 121 dogs (237 eyes) undergoing ophthalmic surgery. Midazolam-butorphanol was administered IV as preanesthetic medication to 15 and 87 dogs with and without glaucoma, respectively. A placebo (lactated Ringer solution) was administered IV to 8 and 11 dogs with and without glaucoma, respectively. Anesthesia of surgical patients was induced with propofol IV to effect. The IOPs and physiologic variables of interest were recorded before (baseline) and after preanesthetic medication or placebo administration and after propofol administration.

RESULTS An IOP > 25 mm Hg was deemed indicative of glaucoma. Compared with baseline measurements, mean IOP was increased after propofol administration in nonpremedicated dogs without glaucoma and unchanged in nonpremedicated dogs with glaucoma. Propofol-associated increases in IOP were blunted in premedicated dogs without glaucoma; IOP in affected eyes of premedicated dogs with glaucoma was decreased after preanesthetic medication and after propofol administration.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that preexisting IOP influences the response to anesthetic drugs, and administration of preanesthetic medication with muscle-relaxing properties may blunt or reduce propofol-induced increases in IOP. Further research with a larger number of dogs is needed to confirm our results in dogs with glaucoma.

Abstract

Objective—To compare the use of a semi-invasive vascular access port (VAP) device or noninvasive oscillometry versus invasive telemetry for blood pressure measurements in cats.

Animals—6 healthy cats.

Procedures—30 days before the study, all cats received an implanted telemeter and a VAP device. During normotension and experimentally induced hypertension, blood pressure was measured with the implanted devices and with noninvasive oscillometry at 4 time points.

Results—Compared with invasive telemetry, VAP had a correlation coefficient from 0.8487 to 0.9972, and noninvasive oscillometry had a correlation coefficient from 0.7478 to 0.9689.

Conclusions and Clinical Relevance—Use of the VAP device and noninvasive oscillometry had a high degree of correlation with invasive telemetry as the gold standard for blood pressure measurement. Use of a VAP device resulted in a slightly higher degree of correlation, compared with noninvasive oscillometry.

Abstract

Objective—To determine the hematologic, serum biochemical, rheological, hemodynamic, and renal effects of IV administration of lactated Ringer's solution (LRS) to healthy anesthetized dogs.

Design—4-period, 4-treatment cross-over study.

Animals—8 healthy mixed-breed dogs.

Procedures—Each dog was anesthetized, mechanically ventilated, instrumented, and randomly assigned to receive LRS (0, 10, 20, or 30 mL/kg/h [0, 4.5, 9.1, or 13.6 mL/lb/h]), IV, on 4 occasions separated by at least 7 days. Blood hemoglobin concentration and serum total protein, albumin, lactate, and electrolyte concentrations; PCV; colloid osmotic pressure; arterial and venous pH and blood gases (Po ₂; Pco ₂); whole blood and plasma viscosity; arterial and venous blood pressures; cardiac output; results of urinalysis; urine production; glomerular filtration rate; and anesthetic recovery times were monitored. Oxygen delivery, vascular resistance, stroke volume, pulse pressure, and blood and plasma volume were calculated.

Results—Increasing rates of LRS administration resulted in dose-dependent decreases in PCV; blood hemoglobin concentration and serum total protein and albumin concentrations; colloid osmotic pressure; and whole blood viscosity. Plasma viscosity; serum electrolyte concentrations; data from arterial and venous blood gas analysis; glomerular filtration rate; urine production; heart rate; pulse, central venous, and arterial blood pressures; pulmonary vascular resistance; and oxygen delivery did not change. Pulmonary artery pressure, stroke volume, and cardiac output increased, and systemic vascular resistance decreased.

Conclusions and Clinical Relevance—Conventional IV infusion rates of LRS to isoflurane-anesthetized dogs decreased colligative blood components; increased plasma volume, pulmonary artery pressure, and cardiac output; and did not change urine production or oxygen delivery to tissues.

Abstract

Objective—To determine the effects of rapid small-volume fluid administration on arterial blood pressure measurements and associated hemodynamic variables in isoflurane-anesthetized euvolemic dogs with or without experimentally induced hypotension.

Design—Prospective, randomized, controlled study.

Animals—13 healthy dogs.

Procedures—Isoflurane-anesthetized dogs were randomly assigned to conditions of nonhypotension or hypotension (mean arterial blood pressure, 45 to 50 mm Hg) and treatment with lactated Ringer's solution (LRS) or hetastarch (3 or 10 mL/kg [1.4 or 4.5 mL/lb] dose in a 5-minute period or 3 mL/kg dose in a 1-minute period [4 or 5 dogs/treatment; ≥ 10-day interval between treatments]). Hemodynamic variables were recorded before and for up to 45 minutes after fluid administration.

Results—IV administration of 10 mL/kg doses of LRS or hetastarch in a 5-minute period increased right atrial and pulmonary arterial pressures and cardiac output (CO) when dogs were nonhypotensive or hypotensive, compared with findings before fluid administration; durations of these effects were greater after hetastarch administration. Intravenous administration of 3 mL of hetastarch/kg in a 5-minute period resulted in an increase in CO when dogs were nonhypotensive. Intravenous administration of 3 mL/kg doses of LRS or hetastarch in a 1-minute period increased right atrial pressure and CO when dogs were nonhypotensive or hypotensive.

Conclusions and Clinical Relevance—Administration of LRS or hetastarch (3 or 10 mL/kg dose in a 5-minute period or 3 mL/kg dose in a 1-minute period) improved CO in isoflurane-anesthetized euvolemic dogs with or without hypotension. Overall, arterial blood pressure measurements were a poor predictor of the hemodynamic response to fluid administration.