Effect of intra-abdominal hypertension on plasma exogenous creatinine clearance in conscious and anesthetized dogs.

OBJECTIVE: To evaluate the effect of intra-abdominal pressure (IAP) on plasma exogenous creatinine clearance in both conscious and anesthetized dog models using a balloon technique to generate intra-abdominal hypertension. DESIGN: Prospective, cross-over, experimental study. SETTING: University-based small animal research facility. ANIMALS: Six healthy male Beagle dogs. INTERVENTIONS: A balloon device comprising a Foley urinary catheter and latex balloon was placed in the intra-abdominal cavity. Plasma exogenous creatinine clearance was compared after intravenous administration of exogenous creatinine solution at 80 mg/kg under 4 different treatment conditions as follows: control and IAP levels of 25 mm Hg in conscious dogs and control and IAP levels of 25 mm Hg in anesthetized dogs (CC, C25, AC, and A25, respectively). Samples were obtained before (T0) and 10, 20, 30, 60, 90, 120, 240, 360, 480, and 600 min after administration of creatinine in all treatment groups. MEASUREMENTS AND MAIN RESULTS: There were no significant differences in plasma creatinine concentration for CC, AC, and C25 during the treatment period. However, in the A25 treatment condition, the plasma creatinine concentration increased significantly at 10, 20, 30, 60, 90, and 120 min after administration of creatinine (P < 0.05). Plasma creatinine clearances were 5.0 ± 0.5, 4.7 ± 1.2, 5.5 ± 0.9, and 2.5 ± 0.5 mL/kg/min for 600 min (CC, AC, C25, and A25, respectively). In the A25 treatment condition, the plasma exogenous creatinine clearance decreased significantly to 50%, 47%, and 55% of that under control conditions (CC, AC, and C25, respectively). After decompression of the abdomen, plasma creatinine concentrations declined rapidly and returned to basal concentrations. CONCLUSIONS: Intra-abdominal hypertension under general anesthesia could cause renal hypoperfusion. Timely decompression may improve the outcome of acutely increased IAP when surgery and/or general anesthesia is required in canine patients.

Effects of Intramuscular Alfaxalone/Acepromazine on Echocardiographic, Biochemical, and Blood Gas Measurements in Healthy Cats.

The effects of intramuscular injection of alfaxalone ([ALF] 5 mg/kg), acepromazine ([ACE] 0.05 mg/kg), and an ALF-ACE combination ([AA] 0.025 mg/kg ACE followed by 2.5 mg/kg ALF) on the sedation, echocardiographic, biochemical, and blood gas indexes and recovery were evaluated in seven cats. No sedation was obtained with ACE, and sedation scores were higher with ALF than with AA treatment. Compared with baseline, an increase in heart rate occurred after ACE, and all treatments caused a decrease in systemic arterial pressure. Decreased left ventricular internal dimension in diastole, end-diastolic volume of the left ventricle, stroke volume, and left atrial dimension were identified after AA. There were minimal changes in echocardiographic variables after ALF. Biochemical and blood gas analysis showed no significant changes after all treatments. Although the difference in quality of recovery between the AA and ALF treatment groups was insignificant, all cats treated with AA or ALF showed ataxia. The AA combination did not change the recovery score, and tremor and twitching were identified more frequently with AA than ALF. ALF had no significant effects on echocardiographic, biochemical, or blood gas variables. ALF could be considered a useful sedative option for diagnostic procedures and echocardiography in cats.

Cranial versus caudal thoracic epidural anesthesia using three volumes of lidocaine in conscious Beagle dogs.

OBJECTIVE: To compare the effects of epidural injection of three volumes of lidocaine injected at the third (T3) or eleventh thoracic vertebra (T11) in conscious dogs to induce thoracic epidural anesthesia (TEA) and to measure the epidural dispersion of iohexol under similar conditions. STUDY DESIGN: Prospective crossover experiment. ANIMALS: A group of five Beagle dogs weighing 10.4 ± 0.5 kg (mean ± standard deviation). METHODS: Each dog was anesthetized twice, separated by 1 week, for inserting an epidural catheter at the lumbosacral space and advancing the tip to T3 (treatment TEAT3) or T11 (treatment TEAT11). For each treatment, three volumes of 2% lidocaine (0.05, 0.10 and 0.20 mL kg-1) were administered at 24 hour intervals, and sensory blockade (SB) of dermatomes was estimated by pinching the skin with mosquito forceps. Under identical conditions of injection volume and site, iohexol was administered 3 hours after lidocaine injection to identify epidural distribution (ED) using computed tomography. The effects of injection site and volume on SB of thoracic dermatomes and ED were analyzed using a linear mixed model (p < 0.05). RESULTS: Thoracic SB and ED significantly increased as the volume increased (p < 0.001 and p < 0.001, respectively), and significantly decreased in TEAT3 than in TEAT11 (p = 0.011 and p = 0.002, respectively). Cervical SB was obtained in three of five dogs in TEAT3 and two of five dogs in TEAT11 injected with 0.20 mL kg-1. One dog showed temporary inspiratory stridor probably caused by bilateral laryngeal paralysis, but no hypoxia. CONCLUSIONS AND CLINICAL RELEVANCE: TEA induced at T3 produced less thoracic SB than did TEA at T11 with the same volumes of lidocaine. The cervical SB obtained with the highest volume of lidocaine may increase the risk of laryngeal paralysis and pulmonary aspiration.

A novel balloon technique to induce intra-abdominal hypertension and its effects on cardiovascular parameters in a conscious dog model.

OBJECTIVE: To evaluate a new balloon technique to induce intra-abdominal hypertension (IAH) and abdominal compartment syndrome in a conscious dog model, and to evaluate the effect of intra-abdominal pressure (IAP) on cardiovascular, respiratory, and arterial blood gas values in conscious dogs with IAH. DESIGN: Prospective, experimental study. SETTING: University-based small animal research facility. ANIMALS: Six healthy Beagle dogs, 4 males, and 2 females. INTERVENTIONS: A new balloon device designed for this study using a Foley urethral catheter and latex balloon was placed in the abdominal cavity. Consecutive measurements of IAP were made by measuring the intravesicular pressure. The abdomen was inflated with air to IAPs of 10, 15, 20, and 25 mm Hg. Heart rate, respiratory rate, systolic arterial blood pressure, and arterial blood gases were evaluated at baseline and at 15, 30, 45, 60, 120, 240, and 300 minutes after IAP increase. MEASUREMENTS AND MAIN RESULTS: The air insufflated into the intra-abdominal balloon device significantly increased the IAP and led to sustained IAH. The respiratory rate increased significantly (P < 0.05) when IAP was increased to 15, 20, and 25 mm Hg. Although heart rate, systolic arterial blood pressure, PaO2 , and PaCO2 did not show statistically significant differences between baseline and posttreatment values over time, the dogs with increased IAP showed a distended abdomen and apparent discomfort, and 4/6 (67%) vomited. After measurement of IAP, air was removed. There were no adverse effects noted after removal of the balloon device. CONCLUSION: The balloon device was successfully insufflated and led to sustained IAH in conscious dogs. This balloon technique does not require general anesthesia for instillation or removal of gas after installment. An acute IAP increase in normal conscious dogs induced discomfort, vomiting, and increased respiratory effort.

Effect of tiletamine-zolazepam on the intraocular pressure of the dog.

OBJECTIVE: To determine the effect of tiletamine-zolazepam (TZ) on canine intraocular pressure (IOP). ANIMALS STUDIED: Six healthy dogs without ocular abnormalities were used in this study. PROCEDURES: The study was carried out as a crossover experimental trial with a 7-day interval between treatments. TZ combination was administered intravenously (IV) at a dose of 5, 10, and 20 mg/kg (TZ5, TZ10, and TZ20, respectively). Following preanesthetic baseline readings of IOP, each dog received IV TZ and then the IOP values were measured every 10 min for 40 min in all treatments. RESULTS: The baseline IOP values (mean ± standard deviation) for TZ5, TZ10, and TZ20 were 12.7 ± 0.8, 14.4 ± 1.2, and 15.3 ± 1.7 mmHg, and each IOP changed to 11.1 ± 1.1, 13.1 ± 1.4 and 13.5 ± 1.7 mmHg after intravenous administration of each TZ treatment, respectively. However, there were no statistical differences between baseline and post-treatment values. CONCLUSIONS: The TZ combination had no clinically significant effect on IOP of the dog. This could be an option for induction or surgical procedures in dogs with ophthalmic problems when an increase in IOP is undesirable.

The volume effect of lidocaine on thoracic epidural anesthesia in conscious Beagle dogs.

OBJECTIVE: To evaluate the volume effect of local anesthetic solution on thoracic epidural analgesia in dogs. STUDY DESIGN: Prospective, experimental trial. ANIMALS: Five healthy adult Beagle dogs weighing 9.7 ± 1.3 kg. METHODS: A catheter was inserted into the seventh thoracic epidural space using a lumbosacral approach, and secured with suture under total intravenous (IV) anesthesia with propofol. Each dog was administered four volume treatments (0.05, 0.10, 0.15 and 0.20 mL kg(-1)) of 2% lidocaine via the catheter at 12 hour intervals. In every treatment, dogs were re-anesthetized with propofol (6 mg kg(-1), IV) and isoflurane, and received iohexol at each volume to visualize the epidural distribution (ED) through computed tomography. Three hours after epidurography, when dogs had recovered from anesthesia, the appropriate volume of lidocaine was injected through the catheter, and sensory blockade (SB) in dermatomes was evaluated by pinching with a mosquito forceps. Results were presented as median (range), and the volume effect on ED and SB was analyzed with one-way Kruskal-Wallis anova. RESULTS: In proportion to volumes (0.05, 0.10, 0.15 and 0.20 mL kg(-1)), there were significant increases in the extent of ED from 7.4 (5.5-9.0) to 10.4 (8.0-12.0), 13.2 (12.5-13.0), and 15.2 (13.0-18.0) vertebrae, respectively, p < 0.001, and in SB from 2.7 (1.0-5.0) to 6.8 (4.5-10.5), 9.9 (6.5-13.0), and 13.1 (11.0-15.0) dermatomes, respectively, p < 0.001. Unilateral ED and SB were observed in all treatments with various grades, and this distribution was more frequent in the low volume treatments. In the high volume treatments, temporary complications including Horner's syndrome, ataxia, paraplegia, depression, stupor, and intermittent cough occurred often. CONCLUSIONS AND CLINICAL RELEVANCE: The increase in volume of local anesthetic solution improved SB by resulting in more consistent bilateral dermatome blockade as well as an extended blockade. However, caution should be exerted, as higher volume injections of lidocaine caused side effects in all dogs.