Erik H. Hofmeister

Prognostic indicators for dogs and cats with cardiopulmonary arrest treated by cardiopulmonary cerebral resuscitation at a university teaching hospital.

OBJECTIVE To determine the association among signalment, health status, other clinical variables, and treatments and events during cardiopulmonary cerebral resuscitation (CPCR) with the return of spontaneous circulation (ROSC) for animals with cardiopulmonary arrest (CPA) in a veterinary teaching hospital. DESIGN Cross-sectional study. ANIMALS 161 dogs and 43 cats with CPA. PROCEDURES Data were gathered during a 60-month period on animals that had CPA and underwent CPCR. Logistic regression was used to evaluate effects of multiple predictors for ROSC. RESULTS 56 (35%) dogs and 19 (44%) cats had successful CPCR. Twelve (6%) animals (9 dogs and 3 cats) were discharged from the hospital. Successfully resuscitated dogs were significantly more likely to have been treated with mannitol, lidocaine, fluids, dopamine, corticosteroids, or vasopressin; had CPA while anesthetized; received chest compressions while positioned in lateral recumbency; and had a suspected cause of CPA other than hemorrhage or anemia, shock, hypoxemia, multiple organ dysfunction syndrome, cerebral trauma, malignant arrhythmia, or an anaphylactoid reaction and were less likely to have been treated with multiple doses of epinephrine, had a longer duration of CPA, or had multiple disease conditions, compared with findings in dogs that were not successfully resuscitated. Successfully resuscitated cats were significantly more likely to have had more people participate in CPCR and less likely to have had shock as the suspected cause of CPA, compared with findings in cats that were not successfully resuscitated. CONCLUSIONS AND CLINICAL RELEVANCE The prognosis was grave for animals with CPA, except for those that had CPA while anesthetized.

Transdermal Fentanyl Patches in Small Animals

Fentanyl citrate is a potent opioid that can be delivered by the transdermal route in cats and dogs. Publications regarding transdermal fentanyl patches were obtained and systematically reviewed. Seven studies in cats and seven studies in dogs met the criteria for inclusion in this review. Dogs achieved effective plasma concentrations approximately 24 hours after patch application. Cats achieved effective plasma concentrations 7 hours after patch application. In dogs, transdermal fentanyl produced analgesia for up to 72 hours, except for the immediate 0- to 6-hour postoperative period. In cats, transdermal fentanyl produced analgesia equivalent to intermittent butorphanol administration for up to 72 hours following patch application.

A comparison of the effects of propofol and etomidate on the induction of anesthesia and on cardiopulmonary parameters in dogs.

OBJECTIVE To determine the effects of propofol or etomidate on induction quality, arterial blood pressure, blood gases, and recovery quality in normal dogs. STUDY DESIGN Randomized, blinded trial. ANIMALS Eighteen purpose-bred adult Beagles. METHODS Dogs were randomly assigned to receive propofol at 8 mg kg(-1) or etomidate at 4 mg kg(-1) intravenously (IV) administered to effect. Midazolam was administered at 0.3 mg kg(-1) IV as pre-medication at least 1 minute prior to induction. Direct arterial blood pressure, arterial blood gases, and heart rate were obtained at baseline, before induction, after induction, and for every 5 minutes afterwards until the dog began to swallow and the trachea was extubated. The dogs were allowed to breathe room air with the endotracheal tube in place. RESULTS The systolic arterial pressure (SAP) was higher in the etomidate group compared with the propofol group after induction. The SAP and mean arterial pressure (MAP) were higher in the etomidate group compared with the propofol group at 5 minutes. The recovery quality and ataxia score were worse in the etomidate group compared with the propofol group. Time from extubation to sternal recumbency and sternal recumbency to standing was longer in the etomidate group compared with the propofol group. The heart rate, PaCO(2), and HCO(3) were higher in the propofol group compared with the etomidate group after induction. The PaO(2) and SaO(2) were lower in the propofol group compared with the etomidate group after induction. The SAP and MAP were lower in the propofol group at 5 minutes compared with baseline. CONCLUSION AND CLINICAL RELEVANCE Propofol caused a decrease in SAP and MAP which was not observed with etomidate. Etomidate caused longer and poorer recoveries than propofol.

A comparison of cardiopulmonary and anesthetic effects of an induction dose of alfaxalone or propofol in dogs

OBJECTIVE To compare the physiological parameters, arterial blood gas values, induction quality, and recovery quality after IV injection of alfaxalone or propofol in dogs. STUDY DESIGN Prospective, randomized, blinded crossover. ANIMALS Eight random-source adult female mixed-breed dogs weighing 18.7 ± 4.5 kg. METHODS Dogs were assigned to receive up to 8 mg kg(-1) propofol or 4 mg kg(-1) alfaxalone, administered to effect, at 10% of the calculated dose every 10 seconds. They then received the alternate drug after a 6-day washout. Temperature, pulse rate, respiratory rate, direct blood pressure, and arterial blood gases were measured before induction, immediately post-induction, and at 5-minute intervals until extubation. Quality of induction, recovery, and ataxia were scored by a single blinded investigator. Duration of anesthesia and recovery, and adverse events were recorded. RESULTS The mean doses required for induction were 2.6 ± 0.4 mg kg(-1) alfaxalone and 5.2 ± 0.8 mg kg(-1) propofol. After alfaxalone, temperature, respiration, and pH were significantly lower, and PaCO2 significantly higher post-induction compared to baseline (p < 0.03). After propofol, pH, PaO2 , and SaO2 were significantly lower, and PaCO2 , HCO3 , and PA-aO2 gradient significantly higher post-induction compared to baseline (p < 0.03). Post-induction and 5-minute physiologic and blood gas values were not significantly different between alfaxalone and propofol. Alfaxalone resulted in significantly longer times to achieve sternal recumbency (p = 0.0003) and standing (p = 0.0004) compared to propofol. Subjective scores for induction, recovery, and ataxia were not significantly different between treatments; however, dogs undergoing alfaxalone anesthesia were more likely to have ≥ 1 adverse event (p = 0.041). There were no serious adverse events in either treatment. CONCLUSIONS AND CLINICAL RELEVANCE There were no clinically significant differences in cardiopulmonary effects between propofol and alfaxalone. A single bolus of propofol resulted in shorter recovery times and fewer adverse events than a single bolus of alfaxalone.

Propofol versus thiopental: effects on peri‐induction intraocular pressures in normal dogs

OBJECTIVE To determine the effects of propofol or thiopental induction on intraocular pressures (IOP) in normal dogs. STUDY DESIGN Prospective randomized experimental study. ANIMALS Twenty-two random-source dogs weighing 19.5 +/- 5.3 kg. METHODS Dogs were randomly assigned to receive propofol 8 mg kg(-1) IV (group P) or thiopental 18 mg kg(-1) IV (group T) until loss of jaw tone. Direct arterial blood pressure, arterial blood gasses, and IOP were measured at baseline, after pre-oxygenation but before induction, before endotracheal intubation, and after intubation. RESULTS There were no significant differences between groups with regard to weight, body condition score, breed group, or baseline or before-induction IOP, arterial blood pressure, or blood gases. The baseline IOP was 12.9 mmHg. Before endotracheal intubation, IOP was significantly higher compared to baseline and before induction in dogs receiving propofol. After intubation with propofol, IOP was significantly higher compared to thiopental and was significantly higher compared to before induction. After intubation, IOP was significantly lower compared to before intubation in dogs receiving thiopental. Propofol increased IOP before intubation by 26% over the before-induction score and thiopental increased IOP by 6% at the same interval. The IOP in group P remained 24% over the before induction score whereas thiopental ultimately decreased IOP 9% below baseline after intubation. There was no significant relationship between any cardiovascular or blood gas parameter and IOP at any time. There was no significant relationship between the changes in any cardiovascular or blood gas parameter and the changes in IOP between time points. CONCLUSIONS AND CLINICAL RELEVANCE Propofol caused a significant increase in IOP compared to baseline and thiopental. Thiopental caused an insignificant increase in IOP which decreased after intubation. Propofol should be avoided when possible in induction of anesthesia in animals where a moderate increase in IOP could be harmful.

Paravertebral block for forelimb anesthesia in the dog - an anatomic study.

OBJECTIVE To determine the anatomic landmarks for performing paravertebral forelimb block in the dog. STUDY DESIGN Technique description. ANIMALS Nine canine cadavers. METHODS Each intervertebral foramen between the C5 and T2 vertebrae was targeted. With the dog in lateral recumbency, a 20 SWG 3″ spinal needle was placed at a 45 degree angle from a vertical transverse plane (with the dog standing this plane would be perpendicular to the ground) 2-3 cm lateral to the median plane for the three cranial intervertebral foramina and at a 90 degree angle with the same transverse plane 2-3 cm lateral to the median plane for the T1-T2 intervertebral foramina. RESULTS Three out of nine (33%) of the cadavers had successful staining of all four desired nerves and the remaining six (66%) cadavers had successful staining of three of the four nerves. The C6-C7 spinal nerve was successfully stained in all nine cadavers. The other three nerves were each successfully stained in seven out of nine (78%) cadavers. CONCLUSIONS AND CLINICAL RELEVANCE The landmarks allow reliable placement of a solution at the nerves comprising the brachial plexus, allowing anesthesia of the entire forelimb in the dog.

Effects of acepromazine, hydromorphone, or an acepromazine-hydromorphone combination on the degree of sedation in clinically normal dogs

OBJECTIVE To determine the effects of IM administration of acepromazine, hydromorphone, or the acepromazine-hydromorphone combination on degree of sedation in clinically normal dogs and to compare 2 sedation scoring techniques. DESIGN Prospective, randomized, blinded, controlled trial. Animals-46 random-source dogs. PROCEDURES Dogs were assigned to receive IM administrations of acepromazine (0.05 mg/kg [0.023 mg/lb]; [DOSAGE ERROR CORRECTED] n = 12), hydromorphone (0.1 mg/kg [0.045 mg/lb]; 11), acepromazine-hydromorphone (0.5 mg/kg and 0.1 mg/kg, respectively; 12), or saline (0.9% NaCI) solution (0.05 mL/kg [0.023 mL/lb]; 11). Sedation scores were determined at 0 (time of administration), 15, 30, 45, and 60 minutes by use of a subjective scoring system (SSS) and a simple numeric rating scale (NRS). RESULTS Acepromazine caused significantly greater sedation than did saline solution at 15, 30, 45, and 60 minutes. Acepromazine-hydromorphone caused significantly greater sedation than did saline solution at 15, 30, 45, and 60 minutes and than did hydromorphone alone at 30 minutes. Hydromorphone alone did not cause significantly greater sedation than did saline solution. All treatments, including saline solution, caused significantly greater sedation at 45 and 60 minutes, compared with sedation at time 0. There was a significant correlation (r(2) = 0.72) between scores obtained with the SSS and NRS, but the NRS was less sensitive for detecting clinically important sedation. CONCLUSIONS AND CLINICAL RELEVANCE Administration of acepromazine or acepromazine-hydromorphone caused sedation in clinically normal dogs, whereas administration of hydromorphone alone did not. The NRS was a less-reliable measure of sedation.

Effect of duration and type of anesthetic on tear production in dogs

OBJECTIVE To determine effects of duration and type of anesthetic on tear production in dogs. ANIMALS 8 female Beagles. PROCEDURES Each dog was randomly allocated into 1 of 4 groups according to a Latin square design to receive anesthesia as follows: 1 hour with isoflurane, 1 hour with desflurane, 4 hours with isoflurane, and 4 hours with desflurane. Each dog was anesthetized with the selected inhalant 4 times during a 4-week period, with at least 5 days separating anesthetic episodes. Aqueous tear production was measured via the Schirmer I tear test at baseline and 10 minutes, 30 minutes, and 1 hour after induction of anesthesia as well as 2, 3, and 4 hours after induction for the 4-hour groups. Tear production was also measured after the dogs were standing after recovery from anesthesia and 2, 10, and 22 hours after recovery from anesthesia. RESULTS Aqueous tear production was significantly reduced in dogs during anesthesia and returned to baseline values immediately after recovery and until 10 hours after anesthesia in all treatment groups. Inhalant type and duration had no significant effect. Neither lateral recumbency nor left versus right eyes had a significant effect. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that inhalant anesthetics did not reduce tear production after anesthesia and that longer-duration anesthesia did not cause decreased tear production, compared with shorter-duration anesthesia.

Multivariate analysis of factors associated with post-anesthetic times to standing in isoflurane-anesthetized horses: 381 cases

OBJECTIVE To identify anesthesia-related variables which may independently predict time to standing in horses anesthetized with ketamine/diazepam/isoflurane. STUDY DESIGN Retrospective case series. ANIMALS Three hundred and eighty-one horses. METHODS Case records were searched for the years 2000-2003 and 381 horses older than 12 months which weighed at least 200 kg were identified. Data were extracted from the records, and only horses that were anesthetized with xylazine, ketamine, diazepam and isoflurane were included in the analysis. Multiple linear regression was used to relate time to standing with demographic, intraoperative and anesthetic variables. RESULTS Most (326; 86%) horses recovered unassisted and 55 (14%) were assisted in recovery. The model for unassisted recovery had an R(2) of 0.228 with colic (p < 0.0001), anesthesia duration (p < 0.02), temperature nadir (p < 0.02) and duration of hypotension (p < 0.0001) being significant predictors of time to standing. The final model for predicting assisted recovery time had an R(2) of 0.314 with emergency status (p < 0.0001), warm-blood breed (p < 0.04) and intraoperative administration of ketamine (p < 0.004) being the significant predictor. CONCLUSIONS AND CLINICAL RELEVANCE Variables which could be impacted by the anesthetist which would result in a faster time to standing include duration of anesthesia, hypothermia and intraoperative hypotension. However, the contribution of anesthesia factors explained <23% of the variability in recovery time, suggesting that other, more important factors contribute to anesthesia recovery time in horses.

Effects of graded doses of propofol for anesthesia induction on cardiovascular parameters and intraocular pressures in normal dogs

OBJECTIVE To determine the effects of graded doses of propofol on cardiovascular parameters and intraocular pressures (IOP) in normal dogs. STUDY DESIGN Prospective, randomized, modified Latin square, cross-over experimental study. ANIMALS Eleven adult random-source dogs weighing 20.2 +/- 5.7 kg. METHODS There were three treatment groups: propofol 8 mg kg(-1) intravenous (i.v.) until loss of jaw tone (Group P), propofol until loss of jaw tone +20% (Group P20), and propofol until loss of jaw tone +50% (Group P50). Atracurium 0.1 mg kg(-1) i.v. was administered in all treatments immediately after the propofol. All dogs received the three treatments in a randomized order, with at least a one week interval between treatments. Direct arterial blood pressure and IOP by applanation tonometry were obtained at baseline, after 5 minutes of pre-oxygenation (before induction), before, and after intubation. Blood gas samples were obtained at baseline, after pre-oxygenation, and before intubation. RESULTS There was no significant difference in IOP readings at any time point among groups. The IOP was significantly higher before intubation versus before induction in all three groups. There was a significantly smaller change in systolic, mean (MAP), and diastolic (DAP) arterial pressures in the P50 group compared with the P group after intubation. There was a significantly smaller change in MAP and DAP in the P50 group compared with the P20 group after intubation. The increase in CO(2) from before induction to before intubation was significantly greater in the P50 group than in the P or P20 groups. CONCLUSIONS AND CLINICAL RELEVANCE Graded doses of propofol did not affect the increase in IOP observed with propofol induction in normal dogs. Higher doses of propofol are of no apparent additional benefit in animals who cannot tolerate an abrupt increase in IOP but may be of benefit in dogs who cannot tolerate an abrupt increase in blood pressure accompanying orotracheal intubation.