Cardiopulmonary, hematological, serum biochemical and behavioral effects of sevoflurane compared with isoflurane or halothane in spontaneously ventilating goats

The relationship between diet, plasma glucose, and cancer prevalence across vertebrates

Could diet and mean plasma glucose concentration (MPGluC) explain the variation in cancer prevalence across species? We collected diet, MPGluC, and neoplasia data for 160 vertebrate species from existing databases. We found that MPGluC negatively correlates with cancer and neoplasia prevalence, mostly of gastrointestinal organs. Trophic level positively correlates with cancer and neoplasia prevalence even after controlling for species MPGluC. Most species with high MPGluC (50/78 species = 64.1%) were birds. Most species in high trophic levels (42/53 species = 79.2%) were reptiles and mammals. Our results may be explained by the evolution of insulin resistance in birds which selected for loss or downregulation of genes related to insulin-mediated glucose import in cells. This led to higher MPGluC, intracellular caloric restriction, production of fewer reactive oxygen species and inflammatory cytokines, and longer telomeres contributing to longer longevity and lower neoplasia prevalence in extant birds relative to other vertebrates.

Comparison of Propofol or Isoflurane Anesthesia Maintenance, Combined with a Fentanyl-Lidocaine-Ketamine Constant-Rate Infusion in Goats Undergoing Abomasotomy

Simple Summary

General anesthesia in small ruminants is still a challenge under field conditions. Propofol is an injectable short-acting anesthetic used to provide induction and/or anesthesia maintenance. Isoflurane is the inhaled anesthetic more widely used for providing general anesthesia; however, it requires an expensive equipment for its administration, and high doses may produce environmental pollution. Both anesthetics produce dose-related cardiovascular depressant effects. This study aimed to compare the effects of propofol or isoflurane, combined with a constant-rate infusion of fentanyl–lidocaine–ketamine (total [total intravenous anesthesia (TIVA)] and partial intravenous anesthesia [PIVA], respectively) in goats undergoing abomasotomy. Our results showed that both TIVA and PIVA protocols produced a satisfactory quality of anesthesia during surgery, with minimal changes in cardiopulmonary parameters. However, recovery from anesthesia induced by propofol fentanyl–lidocaine–ketamine might be of poor quality.

Abstract

This study aimed to compare, first, the anesthetic and cardiopulmonary effects of propofol or isoflurane anesthetic maintenance in goats receiving a fentanyl–lidocaine–ketamine infusion undergoing abomasotomy and, secondly, to compare the quality of the recovery from anesthesia. Two groups were used: propofol (TIVA) and isoflurane (PIVA). Goats were premedicated with fentanyl (10 μg/kg intravenously [IV]), lidocaine (2 mg/kg, IV), and ketamine (1.5 mg/kg, IV). Anesthesia was induced with propofol and maintenance consisted of fentanyl (10 μg/kg/h, IV), lidocaine (50 μg/kg/min, IV), and ketamine (50 μg/kg/min, IV) as constant-rate infusions (CRIs), combined with either CRI of propofol at initial dose of 0.3 mg/kg/min, IV (TIVA), or isoflurane with initial end-tidal (FE’Iso) concentration of 1.2% partial intravenous anesthesia (PIVA). The mean effective propofol dose for maintenance was 0.44 ± 0.07 mg/kg/min, while the mean FE’Iso was 0.81 ± 0.2%. Higher systolic arterial pressure (SAP) values were observed in total intravenous anesthesia (TIVA) during some time points. Recovery was smooth in PIVA, while restlessness, vocalizations, and paddling were observed in TIVA. Both protocols produced a satisfactory quality of anesthesia during surgery, with minimal impact on cardiopulmonary function. Nevertheless, recovery after anesthesia in TIVA might be of poor quality.

Effects of Isoflurane Anesthesia on the Hematologic Values of Rehabilitated Wild Owls

Isoflurane anesthesia is commonly used for owls when they are being rehabilitated to minimize stress during treatments and procedures, as well as to ensure caretaker safety. However, the effects of isoflurane anesthesia on the hematologic response of owls are not known. To investigate the effects of isoflurane anesthesia on the hematology of owls, 3 phases of investigation were performed on the subject animals: 1) single, short manual- versus single, short isoflurane-restraint episodes (n = 12; 38%); 2) a single, prolonged isoflurane episode (n = 10; 31%); and 3) serial, short isoflurane episodes (n = 10; 31%). All owls were classified as adult, and the sex for most individuals was unknown. Twelve owls (38%) were included in phase 1: 5 great horned owls (Bubo virginianus; 42%), 2 eastern screech owls (Megascops asio; 17%), and 5 barred owls (Strix varia; 42%). A separate cohort of 10 novel owls (31%) were selected for inclusion in both phases 2 and 3: 4 great horned owls (40%), 2 eastern screech owls (20%), 2 barred owls (20%), 1 barn owl (Tyto alba; 10%), and 1 snowy owl (Bubo scandiacus; 10%). For each anesthetic episode, blood was collected within 3 minutes of capture and in 15-minute intervals according to the duration of the procedure. Phase 2 had additional blood collections with the patient awake at 2 and 24 hours after time 0 blood collection, whereas phase 3 had an additional blood collection at 24 hours after time 0 blood collection. Hematologic analyses included packed cell volume, total solids, total white blood cell count, heterophil to lymphocyte ratio, and absolute heterophil, lymphocyte, monocyte, eosinophil, and basophil counts. Total white blood cell count decreased significantly during phase 1; packed cell volume decreased significantly during phases 2 and 3; total solids decreased significantly in phase 2; phase 2 demonstrated a lymphopenia with a concurrent decrease in the heterophil to lymphocyte ratio; and phase 3 demonstrated a heteropenia and significant changes in the eosinophil count. All hematologic changes noted in the study were within appropriate reference intervals for the owls but do suggest that there are physiologic consequences of restraining and anesthetizing these avian patients.

Evaluation of Sevoflurane Anesthesia in Donkeys (Equus asinus) Premedicated With Xylazine and Induced With Thiopental

Sevoflurane is a volatile anesthetic agent that has become popular in the field of large animal anesthesia. The aim of this study was to evaluate the use of sevoflurane in adult healthy donkeys. Six male, adult, healthy donkeys were premedicated with xylazine (1 mg/kg IV), induced with thiopental (5 mg/kg IV), and then maintained for 90 minutes with sevoflurane in 100% oxygen at a flow rate of 6 L/min with spontaneous breathing. Rectal temperature (RT), respiratory rate, heart rate (HR), oxygen hemoglobin saturation (OHS), and mean arterial blood pressure (MBP) were measured before and 20 minutes after the administration of xylazine, 10 minutes after the injection of thiopental, and then continuously every 10 minutes until recovery. Times for various signs of recovery, total duration of recovery, and quality of recovery were recorded. Jugular blood samples were collected from each donkey and complete blood counts and venous blood gases including concentrations of oxygen (PO₂) and carbon dioxide (PCO₂) were measured. In addition, the concentrations of sodium, potassium, calcium, lactate, bicarbonate, and glucose in venous blood were measured. Results showed that during the anesthesia maintained with sevoflurane, there was a significant decrease in HR, MBP, RT, red blood corpuscles, hematocrit, total white blood cells, neutrophils, and lymphocytes, whereas the levels of OHS and glucose significantly increased. The concentrations of PO₂, PCO₂, and lactate in venous blood significantly increased, whereas the pH significantly decreased. The levels of calcium significantly decreased immediately following the recovery. Sternal recumbency and standing occurred 15.8 ± 2.6 minutes and 28.2 ± 2.2 minutes, respectively, after turning off the vaporizer. Overall, the quality of recovery was good and relatively quick. It was concluded that sevoflurane appears to provide safe and effective anesthesia in donkeys, with relatively rapid induction and recovery.

Determination of the minimum infusion rate of propofol required to prevent purposeful movement of the extremities in response to a standardized noxious stimulus in goats

OBJECTIVE

To determine the minimum infusion rate (MIR) of propofol required to prevent purposeful movement in response to a standardized stimulus in goats.

STUDY DESIGN

Prospective, experimental study.

ANIMALS

Eight healthy goats (four does, four wethers).

METHODS

Anaesthesia was induced with 4 mg kg(-1) propofol intravenously (IV). A continuous IV infusion of propofol at 0.6 mg kg(-1)  minute(-1) was initiated immediately to maintain anaesthesia. Following endotracheal intubation, goats breathed spontaneously via a circle breathing system delivering supplementary oxygen. The initial propofol infusion rate was maintained for 30 minutes before responses to noxious stimulation provided by clamping the proximal part of the claw with a Vulsellum forceps for 60 seconds were tested. In the presence or absence of purposeful movements of the extremities, the infusion rate was increased or reduced by 0.1 mg kg(-1)  minute(-1) and held constant for 30 minutes before claw clamping was repeated. The propofol MIR for each goat was calculated as the mean of the infusion rates that allowed and abolished movement. Basic cardiopulmonary parameters were monitored, recorded and tested for statistical significance using Wilcoxon's signed rank test with Bonferroni adjustment for multiple testing. The quality of recovery from anaesthesia was assessed and scored.

RESULTS

The median MIR of propofol was 0.45 mg kg(-1)  minute(-1) (range: 0.45-0.55 mg kg(-1)  minute(-1) ). Induction and recovery were free of adverse behaviour. No statistically significant cardiopulmonary changes in comparison with baseline were observed, but clinically relevant hypoxaemia at 2 minutes after induction of anaesthesia was consistently observed. Chewing during anaesthesia was observed in three goats. Median times to extubation and standing were 3 minutes (range: 2-6 minutes) and 10 minutes (range: 7-21 minutes), respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Propofol induction and maintenance of general anaesthesia minimally compromise cardiopulmonary function when oxygen is supplemented in goats.

Clinicophysiological and haemodynamic effects of fentanyl with xylazine, medetomidine and dexmedetomidine in isoflurane-anaesthetised water buffaloes (Bubalus bubalis)

The present study was undertaken to investigate the sedative, analgesic and clinical effects of xylazine, medetomidine and dexmedetomidine with fentanyl as pre-anaesthetics in water buffaloes and to compare the dose-sparing effect of xylazine, medetomidine and dexmedetomidine on thiopental for induction and isoflurane for maintenance of anaesthesia in water buffaloes. Six male water buffaloes randomly received intravenous fentanyl (5.0 µg/kg body weight) and xylazine (0.05 mg/kg body weight), fentanyl (5.0 µg/kg body weight) and medetomidine (2.5 µg/kg body weight), fentanyl (5.0 µg/kg body weight) and dexmedetomidine (5.0 µg/kg body weight) at weekly intervals in groups I1, I2 and I3, respectively. After 15 min, the animals were restrained in right lateral recumbency and anaesthesia was induced by 5% thiopental sodium administered intravenously. The intubated animal was connected to the large animal anaesthesia machine and isoflurane in 100% oxygen (5 L/min) was insufflated for 60 min. The treatments were compared by clinicophysiological, haematobiochemical and haemodynamic parameters. Fentanyl-medetomidine and fentanyl-dexmedetomidine produced more cardiovascular depression during the pre-anaesthetic period but less depression of cardio-respiratory dynamics in the post induction and maintenance period. Quicker recovery was recorded in I2 and I3 groups. A lower dose of thiopental was required in group I3 (4.33 mg/kg ± 0.66 mg/kg) than in groups I2 (4.41 mg/kg ± 0.98 mg/kg) and I1 (4.83 mg/kg ± 0.79 mg/kg). The dose of isoflurane was less in group I3 (45.50 mL ± 5.45 mL) than in group I1 and I2 (48.66 mL ± 5.10 mL and 48.00 mL ± 6.38 mL). Better anaesthesia was recorded with fentanyl-dexmedetomidine-thiopental-isoflurane (group I3) than with fentanyl-medetomidine-thiopental-isoflurane (group I2) and fentanyl-xylazine-thiopental-isoflurane (group I1). Fentanyl-medetomidine and fentanyl-dexmedetomidine were better pre-anaesthetic agents in comparison to fentanyl-xylazine for thiopental and isoflurane anaesthesia. Fentanyl-dexmedetomidine-thiopental-isoflurane and fentanyl-medetomidine-thiopental-isoflurane produced effective surgical anaesthesia and were found to be safe, as cardio-pulmonary functions were well preserved during maintenance anaesthesia with no deleterious effect on vital organ functions in water buffaloes.

Intravenous anaesthesia in goats: A review

Intravenous anaesthesia is gradually becoming popular in veterinary practice. Traditionally, general anaesthesia is induced with intravenous drugs and then maintained with inhalation agents. Inhalation anaesthetic agents cause more significant dose-dependent cardiorespiratory depression than intravenous anaesthetic drugs, creating a need to use less of the inhalation anaesthetic agents for maintenance of general anaesthesia by supplementing with intravenous anaesthesia drugs. Better still, if anaesthesia is maintained completely with intravenous anaesthetic drugs, autonomic functions remain more stable intra-operatively. Patient recovery from anaesthesia is smoother and there is less pollution of the working environment than happens with inhalation anaesthetic agents. Recently, a number of drugs with profiles (pharmacokinetic and pharmacodynamic) suitable for prolonged intravenous anaesthesia have been studied, mostly in humans and, to a certain extent, in dogs and horses. There is currently very little scientific information on total intravenous anaesthesia in goats, although, in the past few years, some scholarly scientific articles on drugs suitable for partial intravenous anaesthesia in goats have been published. This review article explored the information available on drugs that have been assessed for partial intravenous anaesthesia in goats, with the aim of promoting incorporation of these drugs into total intravenous anaesthesia protocols in clinical practice. That way, balanced anaesthesia, a technique in which drugs are included in anaesthetic protocols for specific desired effects (hypnosis, analgesia, muscle relaxation, autonomic stabilisation) may be utilised in improving the welfare of goats undergoing general anaesthesia.

Effects of propofol on isoflurane minimum alveolar concentration and cardiovascular function in mechanically ventilated goats

OBJECTIVE

To evaluate the effects of propofol, on isoflurane minimum alveolar concentration (MAC) and cardiovascular function in mechanically ventilated goats.

STUDY DESIGN

Prospective, randomized, crossover experimental study.

ANIMALS

Six goats, three does and three wethers.

METHODS

General anaesthesia was induced with isoflurane in oxygen. Following endotracheal intubation, anaesthesia was maintained with isoflurane in oxygen. Intermittent positive pressure ventilation was applied. Baseline isoflurane MAC was determined, the noxious stimulus used being clamping a claw. The goats then received, on separate occasions, three propofol treatments intravenously: bolus of 0.5 mg kg(-1) followed by a constant rate infusion (CRI) of 0.05 mg kg(-1) minute(-1) (treatment LPROP); bolus of 1.0 mg kg(-1) followed by a CRI of 0.1 mg kg(-1) minute(-1) (treatment MPROP), bolus of 2.0 mg kg(-1) followed by a CRI of 0.2 mg kg(-1) minute(-1) (treatment HPROP). Isoflurane MAC was re-determined following propofol treatments. Plasma propofol concentrations at the time of MAC confirmation were measured. Cardiopulmonary parameters were monitored throughout the anaesthetic period. Quality of recovery was scored. The Friedman test was used to test for differences between isoflurane MACs. Medians of repeatedly measured cardiovascular parameters were tested for differences between and within treatments using repeated anova by ranks (p<0.05 for statistical significance).

RESULTS

Isoflurane MAC [median (interquartile range)] was 1.37 (1.36-1.37) vol%. Propofol CRI significantly reduced the isoflurane MAC, to 1.15 (1.08-1.15), 0.90 (0.87-0.93) and 0.55 (0.49-0.58) vol% following LPROP, MPROP and HPROP treatment, respectively. Increasing plasma propofol concentrations strongly correlated (Spearman rank correlation) with decrease in MAC (Rho=0.91). Cardiovascular function was not affected significantly by propofol treatment. Quality of recovery was satisfactory.

CONCLUSIONS AND CLINICAL RELEVANCE

In goats, propofol reduces isoflurane MAC in a dose-dependent manner with minimal cardiovascular effects.

Anesthesia and analgesia in sheep and goats

Physical or chemical restraint, with or without local anesthesia, has been extensively used to perform diagnostic or minor surgical procedures in small ruminants. However, anesthetic and analgesic techniques are required when specific diagnostic procedures and painful surgery are to be performed. Apart from improving animal welfare standards, anesthesia and analgesia are essential to make the procedures easier and improve both animal and personnel safety. This article provides an overview of the anesthetic and analgesic agents and techniques commonly used in sheep and goats.

Differences in need for hemodynamic support in horses anesthetized with sevoflurane as compared to isoflurane

OBJECTIVE

To study whether hemodynamic function in horses, particularly mean arterial blood pressure (MAP), is better maintained with sevoflurane than isoflurane, thus requiring less pharmacological support.

STUDY DESIGN

Prospective randomized clinical investigation. Animals Thirty-nine racehorses undergoing arthroscopy in lateral recumbency.

METHODS

Horses were assigned to receive either isoflurane (n = 20) or sevoflurane (n = 19) at 0.9-1.0 minimum alveolar concentration (MAC) for maintenance of anesthesia. Besides routine clinical monitoring, cardiac output (CO) was measured by lithium dilution. Hemodynamic support was prescribed as follows: when MAP decreased to <70 mmHg, patients were to receive infusion of 0.1% dobutamine, which was to be discontinued at MAP >85 mmHg or heart rate >60 beats minute(-1). Statistical analysis of results, given as mean +/- SD, included a clustered regression approach.

RESULTS

Average inhalant anesthetic time [91 +/- 35 (isoflurane group) versus 97 +/- 26 minutes (sevoflurane group)] and dose (in MAC multiples), volume of crystalloid solution infused, and cardiopulmonary parameters including CO were similar in the two groups, except heart rate was 8% higher in isoflurane than sevoflurane horses (p < 0.05). To maintain MAP >70 mmHg, isoflurane horses received dobutamine over a significantly longer period (55 +/- 26 versus 28 +/- 21% of total anesthetic time, p < 0.01) and at a 51% higher dose than sevoflurane horses (41 +/- 19 versus 27 +/- 23 microg kg(-1) MAC hour(-1); p = 0.058), with 14/20 isoflurane animals and only 9/19 sevoflurane horses being infused with dobutamine at >30 microg kg(-1) MAC hour(-1) (p < 0.05). Dobutamine infusion rates were consistently lower in the sevoflurane as compared to the isoflurane group, with differences reaching significance level during the 0-30 minutes (p < 0.01) and 61-90 minutes periods (p < 0.05).

CONCLUSIONS AND CLINICAL RELEVANCE

Horses under sevoflurane anesthesia may require less pharmacological support in the form of dobutamine than isoflurane-anesthetized horses. This could be due to less suppression of vasomotor tone.