Efficacy and Safety of Dexmedetomidine Premedication in Balanced Anesthesia: A Systematic Review and Meta-Analysis in Dogs

Effect of dexmedetomidine constant rate infusion on the analgesic duration of peripheral nerve blocks in dogs: a randomized clinical study

The aim of this study was to evaluate whether a constant rate infusion of dexmedetomidine could prolong the analgesic effect of peripheral nerve blocks. Twenty client-owned dogs were enrolled and randomly divided into 2 groups. The DEX group received dexmedetomidine infusion at 1 mcg kg-1 h-1, and the NaCl group received an equivalent volume infusion of saline. Infusions were started after securing vascular access and continued for 10 min, after which intravenous (IV) methadone at 0.2 mg kg-1 and propofol to effect were administered. All animals were maintained with isoflurane in 70% oxygen. Sciatic, saphenous and obturator nerve blocks were performed using 0.1 mL kg-1 0.5% ropivacaine/block. Intraoperative fentanyl was administered if the heart rate and/or mean arterial pressure (MAP) increased > 15% from the previous measurement, and vasopressors were administered if MAP was ≤ 70 mmHg. Postoperative pain was assessed every hour using the Glasgow Composite Pain Scale (GCPS) until the first rescue analgesia administration. Postoperative rescue analgesia (methadone (0.2 mg kg-1 IV) and carprofen (2 mg kg-1 IV)) was administered if the pain score was higher than 6/24 or 5/20. Duration of analgesia was defined as the time between the nerve block procedure and initial postoperative rescue analgesia. Ambulation, proprioception, and skin sensitivity were evaluated to assess the duration of the motor and sensory block. A Student T and chi-square test were used to compare groups for duration of postoperative analgesia and intraoperative fentanyl and vasopressor use, respectively (p values ≤ 0.5 considered significant). A greater number of dogs in the NaCl group required fentanyl (5/10 p = 0.03) and vasopressors (8/10, p = 0.02) than did those in the DEX group (0/10 and 2/10, respectively). The duration of postoperative analgesia was significantly longer (604 ± 130 min) in the DEX group than in the NaCl group (400 ± 81 min, p = 0.0005).Dexmedetomidine infusion at 1 mcg kg-1 h-1 delays the time to first administration of rescue analgesia and reduces intraoperative analgesic and vasopressor requirements during Tibial Tuberosity Advancement surgery.

Anesthetic management of a dog undergoing unilateral adrenalectomy for phaeochromocytoma excision using a partial intravenous anesthetic protocol

Background

The anesthetic management of adrenalectomies for phaeochromocytoma excision, a catecholamine-secreting tumor, is challenging due to the potential for fatal complications following severe hemodynamic variations, including hypertensive crisis following tumor manipulation or sympathetic stimulation, but also severe hypotension and volume depletion post resection.

Case Description

An 11 kg, 15-year-old male neutered Jack Russel Terrier, with mitral valve disease stage B2, was referred for adrenalectomy for phaeochromocytoma resection. The patient was administered per os prazosin 0.11 mg/kg twice a day and amlodipine 0.125 mg/kg once a day for preoperative stabilization. On the day of surgery, the dog received maropitant 1 mg/kg intravenously (IV) and was premedicated with 0.2 mg/kg methadone IV. Anesthesia was induced with alfaxalone 1 mg/kg IV and midazolam 0.2 mg/kg IV and maintained with partial intravenous anesthesia using sevoflurane in 70% oxygen and constant rate infusions of dexmedetomidine 0.5 μg/kg/hour and maropitant 100 μg/kg/hour. After induction of anesthesia, the dog was mechanically ventilated, and a transversus abdominal plane block was performed with ropivacaine 0.2%. The dog remained remarkably stable with a single, self-limiting, hypertension episode recorded intraoperatively. Postoperative rescue analgesia consisted of methadone and ketamine. The dog was discharged 48 hours after surgery, but persistent hypertension was reported at suture removal.

Conclusion

The use of a low-dose dexmedetomidine CRI, a maropitant CRI, and a transversus abdominal plane block provided stable perioperative hemodynamic conditions for phaeochromocytoma excision in a dog.

Evaluation of the Quality of Recovery from General Anesthesia in Dogs with Two Different Low Doses of Dexmedetomidine

The purpose of this study was to evaluate the quality of recovery from general anesthesia with the administration of two low doses of dexmedetomidine in canine patients. For this blind randomized clinical trial study, 30 dogs undergoing general anesthesia for diagnostic procedures or elective surgery (ovariectomy/castration) were included. The patients were randomly divided into three groups, and at the end of anesthesia, they received a bolus of dexmedetomidine at 1 mcg/kg IV (D1), or a bolus of dexmedetomidine at 0.5 mcg/kg (D0.5), or a bolus of NaCl, in a total of 0.5 mL of solution for all three groups. After administration of the bolus, the anesthetist monitored the patients every 5 min by measuring heart rate, systolic and mean blood pressure, respiratory rate, and oxygen saturation. The quality of recovery was also assessed using 4 different scales. The extubation time, time of headlift, and standing position were also recorded. Both groups receiving dexmedetomidine had better awakening and a lower incidence of delirium when compared to saline administration. The heart rate was lower, while the systolic pressure was higher in the two groups D1 and D0.5 compared to the NaCl with a low presence of atrioventricular blocks. The extubation time resulted significantly higher in the D1 (17 ± 6 min) compared to the D0.5 (10 ± 4 min) and NaCl (8 ± 3 min) (p < 0.0001); the headlift time D1 (25 ± 10 min) resulted significantly longer than the NaCl group (11 ± 5 min) (p = 0.0023) but not than the D0.5 (18 ± 9 min). No significant differences were found among the three groups for standing positioning (D1 50 ± 18 min, D0.5 39 ± 22 min, NaCl 28 ± 17 min). The preventive administration of a bolus of dexmedetomidine at a dosage of 0.5 mcg/kg or 1 mcg/kg IV during the recovery phase improves the quality of recovery in patients undergoing general anesthesia.

Effects of atipamezole on selected physiologic parameters in cynomolgus macaques (Macaca fascicularis)

BACKGROUND

Atipamezole, an α-2 adrenergic receptor antagonist, reverses the α-2 agonist anesthetic effects. There is a dearth of information on the physiological effects of these drugs in cynomolgus macaques (Macaca fascicularis). We assessed atipamezole's physiologic effects. We hypothesized atipamezole administration would alter anesthetic parameters.

METHODS

Five cynomolgus macaques were sedated with ketamine/dexmedetomidine intramuscularly, followed 45 min later with atipamezole (0.5 mg/kg). Anesthetic parameters (heart rate, blood pressure [systolic (SAP), diastolic (DAP), and mean (MAP) blood pressure], body temperature, respiratory rate, and %SpO2) were monitored prior to and every 10 min (through 60 min) post atipamezole injection.

RESULTS

While heart rate was significantly increased for 60 min; SAP, DAP, MAP, and temperature were significantly decreased at 10 min.

CONCLUSIONS

This study indicates subcutaneous atipamezole results in increased heart rate and transient blood pressure decrease. These findings are clinically important to ensure anesthetist awareness to properly support and treat patients as needed.

Nebulised adrenaline in the post-operative management of brachycephalic obstructive airway syndrome in dogs: short-term outcomes in 90 cases (2014-2020)

CASE HISTORIES

Medical records from a single UK-based referral hospital were retrospectively reviewed to identify brachycephalic dogs who had undergone corrective airway surgery and were nebulised with adrenaline in the post-operative period. Ninety dogs were identified between August 2014 and March 2020.

CLINICAL FINDINGS

Agitation following nebulisation with adrenaline was uncommon, with 86/90 (96%) dogs remaining calm, and overall outcome was reported as satisfactory in 68 of 73 (89%) dogs for which this information was available. Median respiratory rate at T0 (prior to first nebulisation) and T60 (1 hour following nebulisation) were both 20 breaths/minute with a median difference of 0 (95% CI = 0-0) breaths/minute (p = 0.657). Median heart rate at T0 and T60 were both 80 beats/minute with a median difference of 3 (95% CI = -10 to 7) beats/minute (p = 0.948). Two dogs experienced tachycardia, but this was not associated with the timing of administration of adrenaline. Complications reported in the 24 hours following surgery included regurgitation (n = 36), increased respiratory noise and effort (n = 10), aspiration pneumonia (n = 4), and inappetence (n = 3). A temporary tracheostomy tube was placed in 13 (14.4%) dogs.

CLINICAL RELEVANCE

Nebulisation with adrenaline is feasible, results in minimal increases in respiratory rate and heart rate and is associated with agitation in only a small number of dogs.

Laparoscopic ureteroneocystostomy in the treatment of urinary incontinence due to ectopy of the ureters in female dogs: A pilot study

Ureteral ectopia is rare and requires surgical treatment after a thorough diagnostic workup. Open surgical techniques for repositioning ectopic ureters have been known for many years and are well described in the literature. However, to the best of our knowledge, no laparoscopic method of correcting this pathology has been described, which, in our opinion, would benefit the animal in terms of the healing process and overall clinical outcomes. This study aimed to evaluate the possibility of laparoscopic treatment of ureteral ectopia, which causes urinary incontinence in dogs. All of the operated ten dogs presented in this study were client-owned females with symptoms of urinary incontinence due to a unilateral intramural ectopic ureter. A three-trocar laparoscopic technique was used to perform the ureteroneocystostomy of the ectopic ureter. In this article, clinicopathological data, imaging features, procedural findings, complications, and short- and long-term outcomes are presented. The procedure was feasible in all cases. No major postoperative complications were observed. Among the minor complications, slight hematuria was observed in three dogs, which resolved spontaneously. In the period of at least one year after surgery, no negative impact of the procedure was observed. Seven of the ten operated dogs regained urinary continence. The remaining three dogs required additional surgery (urethral bulking) because of a lack of improvement after adjuvant pharmacological treatment. Overall, good-to-excellent long-term outcomes can be achieved; however, dogs that remain incontinent after laparoscopic ureteroneocystostomy may require additional treatment.

Assessment of a Combination of Tiletamine/Zolazepam, Ketamine, and Dexmedetomidine for Anesthesia of Swine (Sus domesticus)

This study investigated the induction of anesthesia in swine by injection of tiletamine/zolazepam and ketamine in combination with either dexmedetomidine (TKD) or xylazine (TKX). We hypothesized that TKD would accelerate anesthesia onset and prolong recovery as compared TKX in swine undergoing a noninvasive radiographic procedure. A randomized crossover experiment was performed on 6 healthy, intact, male miniature swine undergoing radiographic examination. Swine were randomly assigned to one of 2 groups: 1) 5mg/kg tiletamine/zolazepam, 2.5mg/kg ketamine, and 0.0125mg/kg dexmedetomidine (TKD) or 2) 5mg/kg tiletamine/zolazepam, 2.5mg/kg ketamine, and 2.5mg/kg xylazine (TKX). Either TKD or TKX was administered intramuscularly at 0.05mL/kg to provide anesthesia for a 45-min radiographic procedure. At 45min after drug administration, atipamezole was administered. During anesthesia, swine were monitored for duration parameters (time to sternal recumbency [onset of anesthesia], lateral recumbency, loss of palpebral reflex, return of the palpebral reflex, and return to sternal recumbency [onset of recovery]) and physiologic parameters (heart rate, %SpO₂, noninvasive blood pressure, and body temperature). Duration and physiologic parameters did not differ between groups at any time point. The results indicate TKD and TKX provide comparable general anesthesia in swine undergoing a radiographic examination.

Use of a novel shockwave trode results in better patient acceptance in awake canine patients treated for musculoskeletal disease

Introduction

Extracorporeal shockwave therapy (ESWT) is used as a treatment option for several musculoskeletal pathologies in dogs. When performing ESWT using electrohydraulic devices, sedation is commonly recommended due to the noise and discomfort associated with the treatment. The aim of this study was to compare the tolerance of ESWT delivered by a standard or novel trode in awake canine patients with musculoskeletal disease.

Materials and methods

This was a prospective, blinded clinical trial in which dogs with musculoskeletal disease received awake treatment with ESWT with a gradually increasing energy protocol using both standard and novel trodes with an electrohydraulic generator in a randomized fashion. Noise reactivity and tolerance to treatment as measured in number of shocks and energy level achieved were recorded.

Results

Forty client-owned dogs with pathology affecting the hips, stifles, elbows, or shoulders were enrolled. Thirty-three dogs completed all three treatment sessions, three dogs completed two sessions, and four dogs completed one session. There was evidence of improved patient tolerability with the novel trode, based on an increased average number of shocks delivered (n ± SD = 848 ± 334 for novel trode; n ± SD = 767 ± 358 for standard trode; p = 0.0384) and higher average treatment energy level achieved (E ± SD = 6.5 ± 2.5 for novel trode; E ± SD = 5.3 ± 2.8 for standard trode; p = < 0.001). Decreased noise reactivity was found to be positively correlated with tolerability of shockwave treatment (energy level: p = 0.0168; number of shocks: p = 0.0097).

Discussion

Administration of electrohydraulic ESWT is feasible in select awake patients using a gradually increasing energy protocol, and the tested novel shockwave trode is better tolerated than the standard trode. Further studies are required to determine the efficacy of the novel trode, and if gradually increasing energy protocols are clinically equivalent to current standard protocols that employ a consistent energy level.

Multiple uses of dexmedetomidine in small animals: a mini review

Dexmedetomidine is an alpha-2 adrenergic agonist, which use had an exponential increase in human and veterinary medicine in the last 10 years. The aim of this mini review is to summarize the various uses of dexmedetomidine underlining its new applications and capabilities in the small animals' clinical activity. While this drug was born as sedative in veterinary medicine, some studies demonstrated to be effective as an analgesic both in single administration and in continuous infusion. Recent studies have also shown the role of dexmedetomidine as an adjuvant during locoregional anesthesia, increasing the duration of the sensitive block and consequently decreasing the demand for systemic analgesics. The various analgesic properties make dexmedetomidine an interesting drug for opioid-free analgesia. Some studies highlighted a potential neuroprotective, cardioprotective and vasculoprotective role of dexmedetomidine, thus conferring it a place in critical care medicine, such as trauma and septic patients. Dexmedetomidine has demonstrated to be a multitasking molecule and it is ready to face new challenges.

Repeated Administration of the Cannabinoid WIN Alters the Isoflurane-Sparing Effect of Morphine and Dexmedetomidine

The impacts of morphine and dexmedetomidine on the MAC of isoflurane were studied in rats constantly medicated with the cannabinoid WIN 55,212-2.

METHODS

Prior to the administration of morphine, the MAC was measured in both untreated rats (MAC _(ISO)) and those treated with a cannabinoid (MAC _{(ISO + CANN)}). The effects of morphine (MAC _{(ISO + MOR)}) and dexmedetomidine (MAC _{(ISO + DEX)}) on untreated rats and rats treated for 21 days with the cannabinoids (MAC _{(ISO + CANN + MOR)}) and (MAC _{(ISO + CANN + DEX}) were also studied.

RESULTS

MAC _(ISO) was 1.32 ± 0.06, and MAC _{(ISO + CANN)} was 1.69 ± 0.09. MAC _{(ISO + MOR)} was 0.97 ± 0.02 (26% less than MAC _(ISO)). MAC _{(ISO + CANN + MOR)} was 1.55 ± 0.08 (8% less than MAC _{(ISO + CANN)}), MAC _{(ISO + DEX)} was 0.68 ± 0.10 (48% less than MAC _(ISO)), and MAC _{(ISO + CANN + DEX)} was 0.67 ± 0.08 (60% less than MAC _{(ISO + CANN)}).

CONCLUSIONS

Medication with a cannabinoid for 21 days augmented the MAC of isoflurane. The sparing effect of morphine on isoflurane is lower in rats constantly medicated with a cannabinoid. The sparing effect of dexmedetomidine on the minimum alveolar concentration of isoflurane is greater in rats repeatedly medicated with a cannabinoid.

Dexmedetomidine improves lung compliance in patients undergoing lateral decubitus position of shoulder arthroscopy: A randomized controlled trial

BACKGROUND

The improvement of oxygenation and pulmonary mechanics in patients under general anesthesia can be achieved by dexmedetomidine (DEX) infusion. However, its role in patients undergoing lateral supine shoulder arthroscopy has not been thoroughly studied. This study aimed to evaluate the effect of DEX on lung compliance in patients undergoing shoulder arthroscopic surgery in a lateral decubitus position.

METHODS

The patients who underwent lateral recumbent shoulder arthroscopy under general anesthesia were randomly divided into the DEX group (group D) and the control group (group N). At the start of the trial, group D was given 0.5 μg/kg/hours continuous pumping until 30 minutes before the end of anesthesia; Group N was injected with normal saline at the same volume. The patients were recorded at each time point after intubation: supine position for 5 minutes (T0), lateral position for 5 minutes (T1), lateral position for 1 hour (T2), lateral position for 2 hours (T3), airway peak pressure, platform pressure, dynamic lung compliance, and static lung compliance, etc.

RESULTS

At the end of the drug infusion, the DEX group showed significant improved pulmonary mechanics and higher lung compliance than the control group. Compared with group N, group D's heart rate and mean arterial pressure were lower at all time points; there was no statistical difference in Tidal volume and Pressure end-tidal carbon dioxide data at each time point in Group D.

CONCLUSION

DEX can improve lung compliance and reduce airway pressure and platform pressure of patients undergoing shoulder arthroscopy in the lateral position under general anesthesia.

Dexmedetomidine decreases the 50% effective dose (ED50) of intravenous propofol required to prevent tracheal intubation response in Beagles

OBJECTIVE

To determine the 50% effective dose (ED50) of intravenous propofol required for successfully preventing tracheal intubation response in Beagles co-induced with dexmedetomidine.

ANIMALS

36 adult male Beagles.

PROCEDURES

The dogs were randomly assigned to either group D1, group D2, or group C (received 1 µg/kg, 2 µg/kg dexmedetomidine intravenously, or the same amount of normal saline as dexmedetomidine, 10 mL). The first dog in each group received 6 mg/kg of propofol for induction. The pump speed of propofol was 600 mL/h. The dosage varied with increments or decrements of 0.5 mg/kg based on the Dixon up-and-down method. The duration of eye-opening after propofol administration was recorded. Changes in heart rate (HR) and respiratory rate (RR) were recorded at 5 timepoints: after entering the operation room and prior to propofol administration (T1), 1 and 3 min after propofol administration (T2 and T3), 3 and 5 min after intubation (T4 and T5).

RESULTS

The required ED50 of propofol that prevented tracheal intubation response in D1, D2, and C groups were 6.4 mg/kg (95% CI, 6.1 to 6.7 mg/kg), 5.8 mg/kg (95% CI, 5.67 to 6 mg/kg), and 8.3 mg/kg (95% CI, 8 to 8.5 mg/kg), respectively. The recovery time of group D2 was significantly longer than that of groups D1 and C (P < .05). The differences in HR among the 3 groups were significant from T2 up to T5 timepoint (P < .05). The differences in RR among the 3 groups were significant at T2 and T3 timepoints (P < .05).

CLINICAL RELEVANCE

Dexmedetomidine pre-injection reduces the amount of propofol required for endotracheal intubation response in Beagles, thereby reducing the respiratory inhibition induced by propofol.

Dexmedetomidine Effectively Sedates Asian Elephants (Elephas maximus)

Simple Summary

Sedation in standing procedures is commonly performed in elephants. To successfully and safely initiate standing in elephants, chemical restraint drugs should provide sufficient sedation with minimal complications (i.e., recumbency, significant physiologic alterations, and prolonged recovery). This study investigated the sedative effects of dexmedetomidine in Asian elephants. Results suggest dexmedetomidine 1–2 µg/kg provides effective sedation. However, we suggest a single intramuscular dexmedetomidine injection of 2 µg/kg for approximately 70 min of sedation. This is the first study to demonstrate dexmedetomidine use in Asian elephants.

Abstract

This study investigated the sedative effects of dexmedetomidine in Asian elephants. We hypothesized that 2 µg/kg dexmedetomidine would provide sufficient standing sedation. A crossover design study was performed in three Asian elephants. Each elephant was assigned to 1 of 3 treatment groups—1 (D1), 1.5 (D1.5) or 2 (D2) µg/kg dexmedetomidine (intramuscular injection, IM) with a two-week ‘washout period’ between doses. Elephants were monitored for 120 min. At 120 min (Ta), atipamezole was administered IM. Sedation and responsiveness scores were evaluated. Physiological parameters (pulse rate, respiratory rate, and %SpO₂) and clinical observations were monitored during the study and for 3 days post drug administration. D2 provided the longest sedation (approximately 70 min), compared to D1 and D1.5. After Ta, each elephant’s sedative stage lessened within 10–15 min without complications. No significant abnormal clinical observations were noted throughout and during the 3-days post study period. These data suggest that a single 2 µg/kg IM dexmedetomidine injection provides sufficient standing sedation for approximately 70 min in Asian elephants.

Adoption of Dexmedetomidine in Different Doses at Different Timing in Perioperative Patients

Dexmedetomidine (Dex) is an alpha-2 agonist used for sedation during various procedures. Dex activates 2-adrenoceptors, and causes the decrease of sympathetic tone, with attenuation of the neuroendocrine and hemodynamic responses to anesthesia and surgery; it reduces anesthetic and opioid requirements; and causes sedation and analgesia.

OBJECTIVE

it was to compare the perioperative effects of different doses of Dex at different timing in patients using Dex during the perioperative period adopting a medical data classification algorithm based on optimized semi-supervised collaborative training (Tri-training).

METHODS

495 patients requiring surgical treatment in Xingtai People's Hospital were randomly selected as the study subjects. The patients were divided into group A (used before induction), group B (used during induction), and group C (used after induction) according to different induction timing, with 165 cases in each group. Then, groups A, B, and C were divided into groups A1, B1, and C1 (0.4 μg/(kg·h) rate), groups A2, B2, and C2 (0.6 μg/(kg·h) rate), and groups A3, B3, and C3 (0.8 μg/(kg·h) rate) according to the dose used, with 55 cases in each group. Intraoperative anesthesia and postoperative adverse reactions were compared among the 9 groups.

RESULTS

the similarity between the Tri-training algorithm optimized by Naive Bayes (NB) classification algorithm and the actual classification (93.49%) was clearly higher than that by decision tree (DT) and K-nearest neighbor (kNN) classification algorithm (76.21%, 74.31%); heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) values decreased obviously after Dex used in groups B1, C1, B2, C2, B3, and C3 (P <0.05), but did not change significantly in groups A1, A2, and A3 (P >0.05); the proportion of patients with satisfactory Ramsay score in group A3 was distinctly superior than that in groups A1, A2, B1, B2, B3, C1, C2, and C3 (P <0.05); the incidence of adverse reactions in group A3 was significantly inferior than that in groups A1, A2, B1, B2, B3, C1, C2, and C3 (P <0.05).

CONCLUSION

the optimization effect of NB classification algorithm was the best, and the injection of Dex at the injection rate of 0.8 μg/(kg·h) before induction of anesthesia could apparently improve the fluctuation of HR, SBP, and DBP during perioperative period, and effectively reduce the occurrence of adverse reactions in patients, with better sedative effect on patients.

Clinicophysiological and hematobiochemical effect of dexmedetomidine or diazepam with ketamine and propofol in total intravenous anesthesia in goats

Background

Total intravenous anesthesia (TIVA) is a well-documented anesthetic concept for some animal species, including dogs and horses; however, information about TIVA protocols in goats is currently inadequate. Therefore, this study aimed to compare the clinicophysiological and hematobiochemical effects of dexmedetomidine (DEX) and diazepam premedication with ketamine and propofol.

Result

The DEX-treated group showed a significantly decreased heart rate compared with the diazepam-treated group. Onset of anesthesia and sedation in group I was significantly faster than that in group II (0.33 ± 0.08 and 0.25 ± 0.08 min vs. 3.33 ± 1.53 and 2.0 ± 1.0 min, respectively). Duration of anesthesia and sedation in group I was significantly longer than that in group II (66.67 ± 7.64 and 161.3 ± 43.3 min vs. 37.0 ± 5.19 and 60.33 ± 7.57 min, respectively). The total recovery period in group II was significantly shorter than that in group I (47.0 ± 7.21 vs. 98.33 ± 15.27 min).

Smooth induction and recovery occurred in all goats in group I, whereas most goats in group II exhibited slightly prolonged induction with mild excitation and presence of swallowing reflex and prolonged struggling during recovery.

Conclusion

In TIVA, premedication with DEX produces excellent quality anesthesia, analgesia, sedation, and muscle relaxation. Furthermore, it produces a longer duration of anesthesia, sedation, and analgesia than premedication with diazepam. For these reasons, DEX is more suitable for long surgical procedures, whereas diazepam can be used in minor surgical procedures in goats. Both drug combinations produce hemodynamic stability.