Incidence of and risk factors for poor recovery quality in dogs recovering from general anaesthesia-a prospective case control study

OBJECTIVE

To investigate the incidence of and identify risk factors associated with poor quality of recovery in dogs recovering from general anaesthesia.

STUDY DESIGN

Case controlled study.

METHODS

All dogs undergoing general anaesthesia at the University of Liverpool Small Animal Teaching Hospital between January 2020 and January 2021 were eligible for recruitment. Signalment, anaesthetic case management and a recovery score were recorded. Univariable and multivariable logistic and ordinal logistic regression analysis were used to identify factors which impact incidence of poor quality of recovery.

RESULTS

A total of 247 dogs undergoing general anaesthesia were included. Overall, 72 [29.1%; 95% confidence interval (CI) 23.8%-35.1%] dogs experienced a poor quality recovery. Of these, 40 (55.5%) required sedation to manage behaviours associated with poor recovery. Multivariable logistic regression revealed American Society of Anesthesiologists (ASA) physical status classification of III or higher was associated with a decreased incidence of poor quality recovery [odds ratio (OR) = 0.34, 95% CI 0.12-0.93, p = 0.037] and the use of multiple inhalational anaesthetics during one procedure was associated with an increased incidence of poor quality of recovery (OR = 42.5, 95% CI 3.0-598.3, p = 0.005).

CONCLUSIONS AND CLINICAL RELEVANCE

Poor quality recovery is common in dogs recovering from general anaesthesia and sedation is often required for resolution. It is more likely to occur in healthy veterinary patients (ASA I and II). The use of multiple inhalational anaesthetic agents during one procedure should be discouraged as this may increase the likelihood of poor quality of recovery.

Anaesthetic mortality in dogs: A worldwide analysis and risk assessment

BACKGROUND

Ensuring patient safety during small animal anaesthesia is crucial. This study aimed to assess anaesthetic-related deaths in dogs globally, identify risks and protective factors and inform clinical practice.

METHODS

This prospective cohort multicentric study involved 55,022 dogs from 405 veterinary centres across various countries. Data on anaesthesia-related deaths from premedication to 48 hours post-extubation were collected. Logistic regression was used to analyse patient demographics, American Society of Anesthesiologists (ASA) classification, procedure type and anaesthetic drugs used.

RESULTS

Anaesthetic-related mortality was 0.69%. Most deaths occurred postoperatively (81%). Age, obesity and a higher ASA classification score were associated with increased mortality. Urgent procedures, non-urgent but unscheduled anaesthesias and short procedures also had higher mortality. Some sedatives, systemic analgesics, hypnotics and the use of locoregional anaesthesia were linked to a decrease in mortality.

LIMITATIONS

The limitations of the study include the non-randomised sample, potential selection bias, lack of response rate quantification, variable data quality control, subjectivity in classifying causes of death and limited analysis of variables.

CONCLUSION

Careful patient evaluation, drug selection and monitoring can be associated with reduced mortality. These findings can be used to develop guidelines and strategies to improve patient safety and outcomes. Further research is needed to refine protocols, enhance data quality systems and explore additional risk mitigation measures.

Retrospective assessment of general anesthesia-related challenges, morbidity, and death in snakes: 139 cases (2000-2022)

OBJECTIVE

To summarize the anesthetic events of snakes seen at a large university hospital, identify challenges with record keeping, and assess patient and anesthesia-related morbidity and death.

SAMPLE

139 anesthetic events were performed; only 106 cases had detailed anesthetic reports available for further analyses.

PROCEDURES

Medical records of snakes that underwent general anesthesia between October 2000 and January 2022 were retrospectively reviewed. Only cases with complete anesthesia records were used to assess anesthetic parameters. Collected data included general patient details, diagnoses, procedures, premedication, induction, maintenance, monitoring, and recovery.

RESULTS

A thorough review of the records identified issues or scenarios that resulted in poor record management as well as highlighted the most frequently used anesthetics in snakes. For premedication this was alfaxalone, butorphanol, and hydromorphone, whereas isoflurane, alfaxalone, or propofol were the most common with induction. Lastly, with maintenance, isoflurane was the most popular choice. Of the 139 cases performed, 127 animals recovered, 8 were euthanatized due to poor prognosis, and 4 failed to recover. All snakes that failed to recover had preexisting disease identified pre-, peri-, or postoperatively at necropsy.

CLINICAL RELEVANCE

General anesthesia can be reliably and safely undertaken in snakes without severe preexisting disease. Efforts should be directed at identifying preexisting disease and maintaining and completing anesthesia records, and we recommend an auditing system to identify and correct issues as they arise.

Influence of Constant Rate Infusions of Fentanyl Alone or in Combination With Lidocaine and Ketamine on the Response to Surgery and Postoperative Pain in Isoflurane Anesthetized Dogs Undergoing Unilateral Mastectomy: A Randomized Clinical Trial

The aim of this study was to compare the effects of constant rate infusions (CRI) of fentanyl alone or combined with lidocaine and ketamine (FLK), on physiological parameters, isoflurane requirements and the number of postoperative analgesic rescues in dogs undergoing unilateral mastectomy. Twenty-two dogs were premedicated with acepromazine 0.02 mg/kg and morphine 0.5 mg/kg and anesthetized with propofol and isoflurane. Dogs were randomly assigned to 1 of 2 groups: Fentanyl group (fentanyl 5 µg/kg loading dose [LD] and 9 µg/kg/h CRI; n = 11); FLK group (fentanyl [same doses]; lidocaine 2 mg/kg LD and 3 mg/kg/h CRI; ketamine 1.0 mg/kg LD and 0.6 mg/kg/h CRI; = 11). Intraoperative evaluations were performed before the start of surgery and administration of the treatments (T0); three minutes after the LD (T1); during incision and tissue divulsion (T2); during closure of the surgical wound (T3). Meloxicam (0.1 mg/kg) was administered at T3. Blood samples were collected for determination of plasma concentrations of fentanyl, lidocaine and ketamine. Pain scores and the number of postoperative analgesic rescues with morphine (0.5 mg/kg) were evaluated for 24 hours postoperatively using the short form of the Glasgow Composite Measure Pain Scale. Compared to T0, significant decreases in heart rate (from 84 ± 28 to 53 ± 16 bpm in the Fentanyl group and from 93 ± 16 to 63 ± 15 bpm in FLK) and mean arterial pressure (from 61 ± 5 to 49 ± 10 mmHg in Fentanyl and from 59 ± 3 to 38 ± 6 mmHg in FLK) were observed at T1. Arterial hypotension was transient, with normalization of values at T2 and T3. The expired fraction of isoflurane did not differ significantly between the groups. Plasma concentrations of fentanyl, lidocaine and ketamine remained within the therapeutic range. Postoperatively, the number of dogs requiring analgesic rescue was significantly lower in the FLK (0/11, 0%) than in the Fentanyl group (5/11, 45%). In dogs administered morphine and meloxicam as part of the anesthesia protocol, an intraoperative CRI of FLK abolished the requirement for postoperative analgesic rescue for 24 hours in dogs undergoing mastectomy.

Rabbit Sedation and Anesthesia

With the increasing frequency of rabbits as veterinary patients, the expectation for high-quality, intensive veterinary care, and resultantly an understanding of anesthesia has been increasing. Sedation and general anesthesia are commonly required for many routine and emergency procedures in rabbits, and this results in the need for a strong awareness of anesthetic principles, knowledge of limitations of anesthesia, and maintenance of high standards of anesthesia.

Scoping review of quality of anesthetic induction and recovery scales used for dogs

OBJECTIVE

To compare, describe and assess the level of validation of all instruments measuring quality of induction and recovery from anesthesia in dogs.

DATABASES USED

A search was performed using the electronic database PubMed to find articles containing an induction quality scale, a recovery quality scale or both in dogs. Articles not directly accessible through PubMed were obtained through the Auburn University Library website and Google Scholar. The phrases 'induction scoring systems dogs', 'recovery scoring systems dogs', 'anesthetic induction score dogs', and 'anesthetic recovery score dogs' were used for searches using the 'best match search' function. The time frame searched was from 1980 to May 2020. The search was conducted from March 2020 to May 2020.

CONCLUSIONS

A thoroughly tested and validated scale for measuring the quality of induction and recovery does not exist in the current veterinary literature. A large disagreement exists between studies on the use of induction and recovery scales, and many have reported inconsistent results with current instruments. It is recommended that an induction and recovery scale intended for wide-scale use be constructed and tested extensively for psychometric validation and reliability.

Comparison between dexmedetomidine and acepromazine in combination with methadone for premedication in brachycephalic dogs undergoing surgery for brachycephalic obstructive airway syndrome

OBJECTIVE

To compare dexmedetomidine with acepromazine for premedication combined with methadone in dogs undergoing brachycephalic obstructive airway syndrome (BOAS) surgery.

STUDY DESIGN

Randomized, blinded clinical study.

ANIMALS

A group of 40 dogs weighing mean (± standard deviation) 10.5 ± 6 kg, aged 2.6 ± 1.9 years.

METHODS

Dogs received either acepromazine 20 μg kg^-1 (group A) or dexmedetomidine 2 μg kg^-1 (group D) intramuscularly with methadone 0.3 mg kg^-1. Anaesthesia was induced with propofol and maintained with sevoflurane. Sedation (0-18), induction (0-6) and recovery (0-5) qualities were scored. Propofol dose, hypotension incidence, mechanical ventilation requirement, extubation time, additional sedation, oxygen supplementation, regurgitation and emergency intubation following premedication or during recovery were recorded. Data were analysed using t tests, Mann-Whitney U or Chi-square tests.

RESULTS

Group A dogs were less sedated [median (range): 1.5 (0-12)] than group D [5 (1-18)] (p = 0.021) and required more propofol [3.5 (1-7) versus 2.4 (1-8) mg kg^-1; p = 0.018]. Induction scores [group A: 5 (4-5); group D 5 (3-5)] (p = 0.989), recovery scores [group A 5 (4-5); group D 5(3-5)](p = 0.738) and anaesthesia duration [group A:93 (50-170); group D 96 (54-263) minutes] (p = 0.758) were similar between groups. Time to extubation was longer in group A 12.5 (3-35) versus group D 5.5 (0-15) minutes; (p = 0.005). During recovery, two dogs required emergency intubation (p > 0.99) and five dogs required additional sedation (p > 0.99). Oxygen supplementation was required in 16 and 12 dogs in group A and D, respectively (p = 0.167); no dogs in group A and one dog in group D regurgitated (p = 0.311).

CONCLUSIONS AND CLINICAL RELEVANCE

Dexmedetomidine 2 μg kg^-1 produces more sedation but similar recovery quality to acepromazine 20 μg kg^-1 combined with methadone in dogs undergoing BOAS surgery.

Anesthetic management of a dog with severe subaortic stenosis and mitral valve disease complicated with atrial fibrillation undergoing ovariohysterectomy

The anesthetic management in patients with subaortic stenosis and mitral valve disease should involve intensive monitoring and the anesthesiologist's main concern is to ensure oxygen delivery and tissue perfusion. Since anesthetic procedures in such patients are rare, there is no previous report about the anesthetic management. A 5.5-year old, 32-kg Boxer, suffering a severe heart disease due to a final stage subaortic stenosis and mitral insufficiency, was anesthetized for an ovariohysterectomy to remove an ovarian tumor that was producing high-volume ascites. Methadone (0.3 mg kg^-1) was administered intramuscularly (IM) for pre-anesthetic medication, etomidate (1.3 mg kg^-1) and midazolam (0.2 mg kg^-1) were used for the induction of anesthesia and after endotracheal intubation, anesthesia was maintained with sevoflurane vaporized in oxygen and air. Fentanyl (5-10 μg kg^-1 h^-1) and paracetamol (15 mg kg^-1) were administered to improve analgesia. Previous persistent atrial fibrillation was refractory to medication (digoxin, diltiazem, and pimobendan) and continued during the anesthetic procedure. Dobutamine (1.5-5 μg kg^-1 minute^-1) helped to maintain mean arterial blood pressure above 60 mmHg. Epidural morphine (0.1 mg kg^-1) and incisional bupivacaine (2 mg kg^-1) were administered at the end of surgery to provide postoperative analgesia. Anesthesia was otherwise uneventful, and recovery was considered excellent.

COMPARISON OF ISOFLURANE AND SEVOFLURANE FOR SHORT-TERM ANESTHESIA IN MEERKATS (SURICATA SURICATTA)-ARE THERE BENEFITS THAT OUTWEIGH COSTS?

Meerkats ( Suricata suricatta ) are routinely anesthetized with isoflurane in zoo and field settings. Twenty healthy adult meerkats of mixed age and sex held in the Zoological Society of London's collection were anesthetized with 4% isoflurane by face mask for routine health examinations. The procedure was repeated 5 mo later in the same group of animals utilizing sevoflurane at 5% for induction, and again 3 mo later with sevoflurane at 6.5% for induction to approximate equipotency with isoflurane. The speed and quality of induction and recovery were compared between the two volatile anesthetic agents. There was no statistically significant difference in the speed of induction across any of the anesthetic regimes. There was a significant difference in recovery times between isoflurane and 6.5% sevoflurane (427 ± 218 and 253 ± 65 sec, respectively [mean ± SD]). Under the conditions of this study, sevoflurane at 6.5% induction dose resulted in better quality induction and recovery than sevoflurane at 5% induction or isoflurane. The mean heart and respiratory rates during anesthesia were higher using 5% sevoflurane for induction but there was no significant difference in either rate between isoflurane and sevoflurane used at a 6.5% induction dose. This study suggests that sevoflurane at a dose of 6.5% for induction and 4% for maintenance is a safe and effective anesthetic agent in healthy adult meerkats. Rapid return to normal behavior after anesthesia is important in all zoo species but particularly so in animals with a complex social and hierarchical structure such as meerkats. For this species, the advantage afforded by the speed of recovery with sevoflurane may offset the cost in certain circumstances.

Isoflurane, sevoflurane and desflurane use in cane toads (Rhinella marina)

Anaesthetic chamber concentrations of isoflurane, sevoflurane and desflurane that resulted in loss of righting reflex within 15 minutes in 50 per cent of toads (Rhinella marina) exposed (ED_50-LRR<15MIN) were identified. The median and range ED_50-LRR<15MIN was 1.4 (0.9–1.4) per cent for isoflurane, 1.75 (1.1–1.9) per cent for sevoflurane and 4.4 (4.3–5.5) per cent for desflurane. Subsequently, toads were exposed to 1.5 times the ED_50-LRR<15MIN and times to loss and return of righting reflex were identified. All toads for all anaesthetics lost righting reflex. The median and range loss of righting reflex was 4:00 (3:00–5:30) minutes for isoflurane, 4:45 (3:30–7:00) minutes for sevoflurane, and 4:15 (4:00–5:30) minutes for desflurane and was not different between anaesthetics. Time to return of righting reflex was 175 (123–211) minutes for isoflurane, 192 (116–383) minutes for sevoflurane and 74 (52–220) minutes for desflurane. Time to return of righting reflex was significantly shorter for desflurane compared with isoflurane or sevoflurane. The use of isoflurane, sevoflurane or desflurane can be used to provide immobilisation to cane toads and potentially other anurans. Induction times are likely similar when using an anaesthetic chamber to provide anaesthesia. However recovery time may take twice as long when utilising isoflurane or sevoflurane over desflurane.

Anaesthetic management of a unilateral adrenalectomy of an adrenocortical tumour in a dog

Adrenalectomies in dogs are being more commonly performed, however anaesthetic management of such cases can be challenging due to the multiple aetiologies of adrenal tumours and the physiological role of adrenal glands. This case report describes the anaesthetic management of a dog with clinical signs of hyperadrenocorticism that underwent unilateral adrenalectomy via laparotomy and discusses anaesthetic preparedness, protocol selection and management of complications for dogs undergoing adrenalectomy.

The cardiovascular effects of sevoflurane and isoflurane after premedication of healthy dogs undergoing elective surgery

Sevoflurane and isoflurane are commonly used in veterinary anesthesia. The objective of this prospective, randomized, open-label clinical study was to compare the cardiovascular effects of sevoflurane and isoflurane via direct arterial blood pressure measurements and the lithium dilution cardiac output (LDCO) on premedicated healthy dogs undergoing elective tibial plateau leveling osteotomy (TPLO). Nineteen client-owned dogs were included. All dogs were premedicated with hydromorphone (0.05 mg/kg IV and glycopyrrolate 0.01 mg/kg subcutaneously). Ten dogs were anesthetized with sevoflurane and nine dogs were anesthetized with isoflurane. Eighteen dogs were instrumented with a dorsal pedal arterial catheter, and one dog had a femoral arterial catheter. All dogs had continuous, direct systolic (SAP), diastolic (DAP), and mean arterial (MAP) blood pressure readings as well as heart rate (HR), cardiac output (CO), cardiac index (CI), systemic vascular resistance (SVR), systemic vascular resistance index (SVRI), stroke volume variation (SVV), and pulse pressure variation (PPV) recorded q 5 min during the surgical procedure. There was no significant statistical difference in all parameters between the sevoflurane and isoflurane treatment groups. Both sevoflurane and isoflurane inhalant anesthetics appear to have similar hemodynamic effects when used as part of a multimodal anesthetic protocol in premedicated healthy dogs undergoing an elective surgical procedure.

Alfaxalone for total intravenous anaesthesia in dogs undergoing ovariohysterectomy: a comparison of premedication with acepromazine or dexmedetomidine

OBJECTIVE

To describe alfaxalone total intravenous anaesthesia (TIVA) following premedication with buprenorphine and either acepromazine (ACP) or dexmedetomidine (DEX) in bitches undergoing ovariohysterectomy.

STUDY DESIGN

Prospective, randomised, clinical study.

ANIMALS

Thirty-eight healthy female dogs.

METHODS

Following intramuscular buprenorphine (20 μg kg(-1) ) and acepromazine (0.05 mg kg(-1) ) or dexmedetomidine (approximately 10 μg kg(-1) , adjusted for body surface area), anaesthesia was induced and maintained with intravenous alfaxalone. Oxygen was administered via a suitable anaesthetic circuit. Alfaxalone infusion rate (initially 0.07 mg kg(-1) minute(-1) ) was adjusted to maintain adequate anaesthetic depth based on clinical assessment. Alfaxalone boluses were given if required. Ventilation was assisted if necessary. Alfaxalone dose and physiologic parameters were recorded every 5 minutes. Depth of sedation after premedication, induction quality and recovery duration and quality were scored. A Student's t-test, Mann-Whitney U and Chi-squared tests determined the significance of differences between groups. Data are presented as mean ± SD or median (range). Significance was defined as p < 0.05.

RESULTS

There were no differences between groups in demographics; induction quality; induction (1.5 ± 0.57 mg kg(-1) ) and total bolus doses [1.2 (0 - 6.3) mg kg(-1) ] of alfaxalone; anaesthesia duration (131 ± 18 minutes); or time to extubation [16.6 (3-50) minutes]. DEX dogs were more sedated than ACP dogs. Alfaxalone infusion rate was significantly lower in DEX [0.08 (0.06-0.19) mg kg(-1) minute(-1) ] than ACP dogs [0.11 (0.07-0.33) mg kg(-1) minute(-1) ]. Cardiovascular variables increased significantly during ovarian and cervical ligation and wound closure compared to baseline values in both groups. Apnoea and hypoventilation were common and not significantly different between groups. Arterial haemoglobin oxygen saturation remained above 95% in all animals. Recovery quality scores were significantly poorer for DEX than for ACP dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Alfaxalone TIVA is an effective anaesthetic for surgical procedures but, in the protocol of this study, causes respiratory depression at infusion rates required for surgery.