Search Results

You are looking at 1 - 6 of 6 items for

  • Author or Editor: Paula F. Moon x
  • Refine by Access: All Content x
Clear All Modify Search
Author:

Abstract

Objective

To evaluate duration and magnitude of adrenocortical function suppression after administration of etomidate to cats.

Animals

15 purpose-bred, healthy cats.

Procedure

Cats were allotted to 2 groups. Anesthesia was induced with etomidate (ET, 2 mg/kg of body weight, IV; n = 8) or a mixture (KD, n = 7) of ketamine (5 mg/kg, IV) and diazepam (0.25 mg/kg, IV). Anesthesia was maintained with halothane in all cats for 2 hours. ACTH gel (2.2 U/kg, IM) was administered 30 minutes after anesthesia induction. Blood samples for cortisol assay were taken before anesthesia induction (T −30), and before (TO) and at 30, 60, 120, 180, 300, and 420 minutes after ACTH administration. Anesthesia was discontinued after the T120 sample was obtained.

Results

After anesthesia induction, median (interquartile range [Q1-Q3]) cortisol values were significantly lower in the ET group (4 [3 to 4] μg/dl) at TO, compared with T −30 values and with TO values in the KD group (5 [3 to 9] μg/dl). After ACTH administration, cortisol values in the ET group continued to decrease two- to threefold below T −30 values and remained decreased over the 2-hour anesthesia period. After ACTH administration, cortisol values increased twofold for 2 hours in the KD group, compared with T −30 values. One hour after anesthesia recovery, cortisol values in the ET group (3 [2 to 3] μg/dl) remained significantly lower than values in the KD group (9 [7 to 11] μg/dl) and preanesthesia values. By T300, both groups had cortisol concentration near 7 μg/dl, similar to preanesthesia values.

Conclusion

Induction of anesthesia with etomidate caused suppression of adrenocortical function during 2 hours of halothane anesthesia and 1 hour of recovery in cats. Cortisol concentration did not return to baseline until after 2 additional hours.

Clinical Relevance

Results from these healthy cats suggest profound suppression of important stress hormones after anesthesia induction with etomidate, use of which could put critically ill cats at further risk. (Am J Vet Res 1997;58:868–871)

Free access
in American Journal of Veterinary Research

Summary

Arterial blood samples were collected from 19 anesthetized pigs before and after hemorrhage was induced. Blood gas tensions and concentrations of sodium, potassium, chloride, lactate, and total protein were measured. Results indicated that hydrogen ion (H+) concentration calculated from a specific formula was a biased and imprecise estimate of measured H+ concentration. The bias was 5.45 nEq/L, with limits of agreement from −7.92 to 18.83 nEq/L. Because albumin is the fraction of plasma protein most important in acid-base balance, the agreement between predicted and measured H+ concentration was reevaluated, using an albumin charge estimate and a reference swine albumin-to-globulin ratio. This improved the ability of the formula to predict H+ concentration; the bias decreased to 1.33 nEq/L with limits of agreement from −12.16 to 9.49 nEq/L. The formula and a simplified approach for clinical application were biased and unacceptably imprecise estimators of lactate (L) concentration. The formula approach underestimated L concentration by 2.8 (−12.4, 6.7) mEq/L, whereas the simplified method overestimated L concentration by 5.0 (−3.8, 13.9) mEq/L.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To describe onset and duration of neuromuscular blockade induced by mivacurium chloride and its associated hemodynamic effects at 3 dosages in healthy dogs.

Animals

7 Labrador Retrievers.

Procedure

Anesthesia was induced with thiopental and maintained with halothane in oxygen, and dogs were mechanically ventilated to end-tidal PCO2 between 35 and 40 mm Hg. Core temperature, end-tidal PCO2 , and halothane concentration were kept constant throughout the experiment. Neuromuscular function was assessed by evaluation of the train-of-four response to a supramaximal electrical stimulus of 2 Hz applied to the ulnar nerve every 10 seconds. Blood for determination of plasma cholinesterase activity was obtained prior to administration of mivacurium, a bolus of which was administered IV, using a randomized Latin-square design for dosages of 0.01, 0.02, and 0.05 mg/kg of body weight.

Results

All dogs had typical plasma cholinesterase activity. After administration of mivacurium, differences were not evident between groups in heart rate, systolic, mean, or diastolic blood pressure, change at any time in heart rate, systolic, mean, or diastolic blood pressure, or pH. Interval from onset to 100% neuromuscular blockade was 3.92 ± 1.70, 2.42 ± 0.53, and 1.63 ± 0.25 minutes at dosages of 0.01, 0.02, and 0.05 mg/kg, respectively. Duration of measurable neuromuscular blockade was 33.72 ± 12.73, 65.38 ± 12.82, and 151.0 ± 38.50 minutes, respectively. Time of onset and duration of effect differed significantly among dosages.

Conclusions and Clinical Relevance

Mivacurium provides good hemodynamic stability at the dosages tested. In dogs, this drug has a rapid onset and long duration of effect. (Am J Vet Res 1999;60:1047-1050)

Free access
in American Journal of Veterinary Research

Objective

To describe dogs undergoing cesarean section in the United States and Canada, to determine perioperative management, and to calculate survival proportions.

Design

Multicenter prospective case series.

Animals

3,908 puppies from 808 dams.

Results

Survival rates immediately, 2 hours, and 7 days after delivery were 92, 87, and 80%, respectively, for puppies delivered by cesarean section (n = 3,410) and 86, 83, and 75%, respectively, for puppies born naturally (498). For 614 of 807 (76%) litters, all puppies delivered by cesarean section were born alive. Maternal mortality rate was 1 % (n = 9). Of 776 surgeries, 453 (58%) were done on an emergency basis. The most common breeds of dogs that underwent emergency surgery were Bulldog, Labrador Retriever, Boxer, Corgis, and Chihuahua. The most common breeds of dogs that underwent elective surgery were Bulldog, Labrador Retriever, Mastiff, Golden Retriever, and Yorkshire Terrier. The most common methods of inducing and maintaining anesthesia were administration of isoflurane for induction and maintenance (n = 266; 34%) and administration of propofol for induction followed by administration of isoflurane for maintenance (237; 30%).

Clinical Implications

Mortality rates of dams and puppies undergoing cesarean section in the United States and Canada are low. Knowledge of mortality rates should be useful to veterinarians when advising clients on the likelihood of puppy and dam survival associated with cesarean section. (J Am Vet Med Assoc 1998;213:365-369)

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

Conventional fluid resuscitation is unsatisfactory in a small percentage of equine emergency surgical cases because the large volumes of fluids required cannot be given rapidly enough to adequately stabilize the horse. In anesthetized horses, the volume expansion and cardiopulmonary effects of a small volume of highly concentrated hypertonic saline-dextran solution were evaluated as an alternative initial fluid choice. Seven halothane-anesthetized, laterally recumbent, spontaneously ventilating, normovolemic horses were treated with a 25% NaCl-24% dextran 70 solution (hsd) at a dosage of 1.0 ml/kg of body weight, iv, infused over 10 minutes, and the effects were measured for 120 minutes after infusion. Plasma volume expansion was rapid and significant (from 36.6 ± 4.6 ml/kg to 44.9 ± 4.8 ml/kg), and remained significantly expanded for the duration of the experiment. Packed cell volume, total blood hemoglobin, and plasma protein concentrations significantly decreased, confirming rapid and sustained volume expansion with hemodilution. Cardiac index and stroke index immediately increased and remained high for the entire study (from 69.6 ± 15.3 ml/min/kg to 106.6 ± 28.4 ml/min/kg, and from 1.88 ± 0.49 ml/beat/kg to 2.50 ± 0.72 ml/beat/kg, respectively). Systemic vascular resistance significantly decreased immediately after hsd infusion and remained decreased for the duration of the study (from 1.41 ± 0.45 mm of Hg/ml/min/kg to 0.88 ± 0.22 mm of Hg/ml/min/kg). Arterial and venous blood oxygen content decreased significantly because of hemodilution, but actual oxygen transport transiently increased at the 10-minute measurement before returning toward baseline. Plasma osmolality and sodium significantly increased and remained high for the entire 120 minutes (from 293 ± 2 osm/L to 326 ± 9 mosm/L, and from 142.8 ± 3.3 mM/L to 159.0 ± 6.2 mM/L, respectively). Urine output increased in 5 of 7 horses within minutes of hsd infusion, but the mean increase was not statistically significant.

Three horses developed transiently severe, clinically apparent intravascular hemolysis and hemoglobinuria. One horse developed multiple single premature ventricular contractions during the infusion with no persistent ecg changes after infusion. The potential benefit of using hsd as a rapid volume expander in anesthetized horses was documented because infusion of 1 ml of hsd/kg rapidly increased plasma volume by approximately 8 ml/kg. Substantial side effects developed in these normovolemic horses, however, and this solution requires further investigation before it can be recommended in hemodynamically unstable horses.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine pharmacokinetic variables of mivacurium chloride after IV administration in dogs.

Animals

5 healthy Labrador Retrievers.

Procedure

Anesthesia was induced with thiopental and maintained with halothane in oxygen. Dogs were ventilated mechanically to an end-tidal PCO2 value between 35 and 40 mm Hg. Heart rate, direct blood pressure, and arterial pH were recorded throughout the experiment. Core temperature, end-tidal PCO2 , and halothane concentration were kept constant throughout the experiment. Paired blood samples for determination of plasma cholinesterase activity were collected prior to administration of a bolus of mivacurium (0.05 mg/kg of body weight), which was administered IV during a 2-second period. Arterial blood samples were obtained for determination of plasma mivacurium concentration 0, 1, 3, 5, 10, 30, 60, 120, 150, and 180 minutes after administration of mivacurium. Blood was collected into tubes containing EDTA and 0.25% echothiophate. Mivacurium concentration was determined, using reversed-phase high-performance liquid chromatography.

Results

For the trans-trans isomer, mean ± SEM volume of distribution was 0.18 ± 0.024 L/kg, median half-life was 34.9 minutes (range, 26.7 to 53.5 minutes), and clearance was 12 ± 2 ml/min/kg. For the cis-trans isomer, values were 0.31 ± 0.05 L/kg, 43.4 minutes (range, 31.5 to 69.3 minutes), and 15 ± 2 ml/min/kg, respectively. Values for the cis-cis isomer were not calculated, because it was not detectable in plasma 60 minutes after mivacurium administration in all 5 dogs.

Conclusions and Clinical Relevance

The trans-trans and cis-trans isomers of mivacurium have a long half-life and slow clearance in healthy dogs anesthetized with halothane. (Am J Vet Res 1999;60:1051-1054)

Free access
in American Journal of Veterinary Research