Anaesthetic management in a cat undergoing emergency craniotomy for meningioma excision.

Case summary: A 15-year-old female spayed domestic shorthair cat underwent an emergency craniotomy to remove an intracranial meningioma causing marked midline shift, caudal transtentorial and foramen magnum herniation. Because intracranial structures are enclosed in the cranium, any volume-occupying lesions might raise intracranial pressure (ICP), compromising cerebral perfusion. Relevance and novel information: This case report discusses the anaesthetic management of a cat that presented with marked bradycardia and concomitant hypotension. Cushing's reflex (CR) is a well-recognised cardiovascular reflex following sudden ICP increase, and it features an irregular breathing pattern and increased arterial blood pressure with reflex bradycardia. However, CR is reported to have a low sensitivity for the detection of raised ICP in humans with traumatic brain injury. In a previous study reporting seven cats undergoing surgical removal of intracranial meningioma, ICP was measured in four cases and, in these patients, CR was not observed during surgery. Because bradycardia was not secondary to hypertension, in this case, it might have been the result of direct compression of the nucleus of the vagus nerve. Based on the literature search, there is paucity of reports of cardiovascular changes in cats with increased ICP and their perianaesthetic management.

Incidence of Severe Hypoxemia in Anesthetized Horses Undergoing Emergency Exploratory Laparotomy.

Prevalence and risk factors of severe hypoxemia in anesthetized horses undergoing emergency exploratory laparotomy are sparsely documented. The aim of this study was to report incidence of severe hypoxemia ( PaO2 < 60 mmHg) in horses undergoing emergency exploratory laparotomy and identify potential risk factors for this complication. A single center retrospective cross sectional designed was used. Clinical data of 714 horses undergoing general anesthesia for emergency explorative laparotomy were reviewed. A backward stepwise elimination procedure was used to determine the final multivariable logistic regression model; all covariables with univariable P-values <.25 were incorporated, with retention of covariables with Wald P-values <.05 at each step, in order to determine which explanatory variables would be included in the final model. The overall incidence of severe hypoxemia in our population was 15.3%. Multivariable logistic regression analysis showed that increasing body weight (odds ratio [OR] 1.01, 95% confidence interval [CI] 1.0-1.01, P = .002), colon torsion (OR 3.0, 95% CI 1.3-6.8, P = .006), increased dead space ventilation (OR 1.06, 95% CI 1.04-1.09, P ≤ .001), shorter time between induction of anesthesia and collection of arterial blood gas samples (OR 0.98, 95% CI 0.98-0.99, P ≤ .001) and intratracheal aerosolized salbutamol (OR 13.5, 95% CI 7.6-24, P ≤ .001) were associated with the outcome. The incidence of hypoxemia found in our study was in line with previous literature. Increasing body weight, colon torsion and shorter time between the time of induction of anesthesia and collection of arterial blood gas samples represented risk factors for hypoxemia.

Recovery of horses from general anaesthesia: A systematic review (2000-2020) of the influence of anaesthetic protocol on recovery quality.

BACKGROUND: The recovery phase after equine general anaesthesia (GA) is a time of considerable risk and therefore has been the subject of extensive research over the last 20 years. Various pharmacological interventions have been developed and studied with the objective of improving recovery quality and reducing anaesthetic-related mortality and morbidity. Nevertheless, some controversy remains regarding the influence of anaesthetic protocol choice on recovery quality from GA and its implications for recovery-related mortality and morbidity. A systematic review of the literature investigating the influence of anaesthetic protocol choice on recovery quality is currently lacking. OBJECTIVES: To perform a detailed evaluation of the equine veterinary literature investigating the effect of anaesthetic protocol choice on equine recovery quality utilising the GRADE framework. STUDY DESIGN: A systematic evaluation of the equine veterinary literature was performed using the GRADE framework. METHODS: A literature search was performed and studies were assessed for eligibility by both authors utilising PRISMA guidelines. Studies meeting inclusion criteria were evaluated by both authors, categorically summarised and the quality of evidence for each sub-topic was assessed using the GRADE framework. RESULTS: A total of 124 studies were identified which directly assessed the impact of anaesthetic protocol choice on recovery quality after GA in horses. Evaluation of the available evidence indicated that certain partial intravenous anaesthesia (PIVA) agents, cessation of intravenous lidocaine 30 minutes prior to recovery and provision of adequate analgesia improves recovery quality. MAIN LIMITATIONS: The validity of the results of some studies may have been compromised by missing data and small sample sizes. CONCLUSIONS: There is evidence to indicate that certain PIVA agents, cessation of intravenous lidocaine 30 minutes prior to recovery and provision of adequate analgesia improves recovery quality.

Recovery of horses from general anaesthesia: A systematic review (2000-2020) of risk factors and influence of interventions during the recovery period.

BACKGROUND: In equine anaesthesia, the recovery period is a time of considerable risk and has been the focus of prolific research. Risk factors, including age, type and duration of procedure or temperament may influence recovery quality. Unfortunately, the anaesthetist is unable to control for these factors, therefore various pharmacological interventions and recovery methods have been developed with the objective of improving recovery quality. However, no consensus among anaesthetists has been reached for many of these interventions and their implications for recovery-related mortality and morbidity. OBJECTIVES: To conduct a systematic review of the published evidence relating to risk factors and interventions in the recovery period which may influence recovery quality from equine general anaesthesia (GA). STUDY DESIGN: A systematic evaluation of the equine veterinary literature using the GRADE framework. METHODS: A literature search was performed and studies were assessed for eligibility by both authors utilising PRISMA guidelines. Studies meeting inclusion criteria were evaluated by both authors, categorically summarised and the quality of evidence for each sub-topic was assessed using the GRADE framework. RESULTS: Thirty-nine studies were identified which directly assessed the impact of risk factors and recovery interventions on recovery quality after equine GA. There was evidence to support that peri-anaesthetic risk factors such as anaesthesia duration, American Society of Anesthesiologists (ASA) physical status and surgical procedure influenced recovery quality. We also identified sufficient evidence that administration of α-2 adrenoreceptor agonists immediately prior to recovery, improves recovery quality. MAIN LIMITATIONS: The validity of the results of some studies may have been compromised by missing data and small sample sizes. CONCLUSIONS: Recovery quality is influenced by factors including: anaesthesia duration, ASA physical status and surgical procedure. Recovery quality can be improved by the administration of an α-2 adrenoreceptor agonist immediately prior to recovery.

Head and tail rope-assisted recovery improves quality of recovery from general anaesthesia in horses undergoing emergency exploratory laparotomy.

BACKGROUND: In equine anaesthesia, the recovery period is critical, accounting for most anaesthesia-related fatalities reported. Horses may recover unassisted or may be assisted, for example, using a head and tail rope recovery method. OBJECTIVES: To compare the impact of head and tail rope and unassisted recovery method on quality of recovery in horses undergoing colic surgery under general anaesthesia (GA). STUDY DESIGN: Single centre retrospective cross-sectional study, with prospective model performance analysis. METHODS: Clinical data were obtained from horses undergoing emergency exploratory laparotomy over a 6-year period. Multivariable logistic regression analysis was used to identify the perioperative factors that affect quality of recovery. The final prediction model was assessed prospectively. RESULTS: Records from 502 general anaesthetics (490 horses) were included. Multivariable logistic regression analysis showed that head and tail rope recovery (OR 2.2, 95% CI 1.4-3.3, P < .001) and sevoflurane administration (OR 1.6, 95% CI 1.2-2.3, P = .02) were associated with better quality of recovery when compared with unassisted recovery and isoflurane administration respectively. Increasing GA duration (OR 1.0, 95% CI 0.99-1.0, P = .03), increasing intraoperative dosages (in mg/kg) of thiopental (OR 0.85, 95% CI 0.75-0.98, P = .02) or ketamine (OR 0.67, 95% CI 0.46-0.99, P = .04) were linked to poor quality of recovery. No statistically significant difference was found between recovery groups in terms of mortality. MAIN LIMITATIONS: The clinical prediction model obtained is only applicable to the specific facilities, recovery methodology, referral population and anaesthetic protocols practiced at our institution. CONCLUSIONS: Head and tail rope recovery is significantly associated with better quality of recovery, compared with unassisted recovery, in horses undergoing emergency exploratory laparotomy. Sevoflurane administration, in detriment of isoflurane, was associated with better quality of recovery. Other risk factors, such as increasing GA duration, the use of higher intra-operative dosages of ketamine and/or thiopental, were associated with poor quality of recovery.

Ultrasound-guided erector spinae plane block in horses: a cadaver study.

OBJECTIVES: To describe dye distribution and spinal nerve involvement after a simulated erector spinae plane (ESP) block performed on fresh equine cadavers. STUDY DESIGN: Experimental cadaver study. ANIMALS: A group of 11 adult equine cadavers. METHODS: The spinal region surrounding the sixteenth thoracic vertebra (Th16) of one cadaver was removed and underwent magnetic resonance imaging. In 10 adult equine cadavers [body weight, 549 ± 58 kg (mean ± standard deviation)], 0.2 mL kg-1 of a 50:1 2% lidocaine/dye solution was injected bilaterally (n = 20 injections) into the fascial plane between the transverse process of Th16 and the erector spinae muscles. An in-plane ultrasound-guided technique with a convex transducer was used to guide injection. Dissection was performed immediately following injection. The craniocaudal and lateral extent of dye distribution was measured (cm) and the number of vertebral bodies involved were counted (n = 20). Abdominal and thoracic cavities as well as the epidural space were also examined for presence of dye (yes/no) (n = 20). Further dissection was performed to evaluate if staining of the dorsal and ventral rami of the spinal nerves and sympathetic chain occurred (n = 14). RESULTS: The thoracolumbar fascia was stained in 17/20 (85%) injections and three injections terminated intramuscularly. Multisegmental staining of the dorsal rami was observed in the 14 injections in which staining was evaluated. Ventral rami staining was observed in 3/14 injections where staining was evaluated. Epidural migration was observed in 4/20 (20%) injections. No evidence of dye was found in the thoracic and abdominal cavities or on the sympathetic chain. CONCLUSIONS AND CLINICAL RELEVANCE: The ESP block may prove beneficial to desensitize structures innervated by the dorsal rami of the thoracic spinal nerves. Further investigation is necessary to evaluate complications caused by epidural contamination.