The use of sub-Tenon's anesthesia versus a low-dose neuromuscular blockade for canine cataract surgery: A comparative study of 224 eyes

OBJECTIVE

Assess the utility of a Sub-Tenon's anesthesia (STA) protocol to provide suitable operating conditions for canine cataract surgery and compare it to an alternative low-dose neuromuscular blockade (LD-NMB) protocol used for canine cataract surgery.

PROCEDURES

Clinical study of dog eyes undergoing cataract surgery with either an STA or LD-NMB protocol. While intraoperative vitreal expansion scores and intraoperative complications were collected prospectively, globe position, intraocular pressure, return of vision, and postoperative complications were collected retrospectively. Statistical testing was used to compare results between the STA and the LD-NMB groups for the data available.

RESULTS

A total of 224 eyes from 126 dogs were assessed, with 133/224 (59.4%) eyes from 99/126 (78.6%) dogs receiving STA and 91/124 (40.6%) eyes from 72/126 (57.1%) dogs receiving LD-NMB. Forty-five of these dogs (45/126; 37.7%) received STA for one eye and LD-NMB for the other eye. There was no significant change in intraocular pressure measurements following STA administration. This was not measured for the LD-NMB group. The globe achieved a central position in 110/133 (82.7%) of eyes that received STA. This was not measured for the LD-NMB group. Intraoperative vitreal expansion scores were slightly higher in STA-treated eyes compared to LD-NMB-treated eyes. The intraoperative complication rate for STA-treated eyes was higher (73/133; 54.8%) compared to NMB-treated eyes (12/91; 13.2%). The most common intraoperative complication for STA was chemosis (64/133; 48.1%), the risk of which increased with an increase in the volume of local anesthetic injected. The post-operative complication rate was higher in STA-treated eyes (28/133; 21.1%) compared to NMB-treated eyes (16/91; 17.6%). Post-operative corneal ulceration was the most common postoperative complication in STA-treated eyes (6/133; 4.5%).

CONCLUSION

The STA protocol described resulted in suitable operating conditions, but more intraoperative and postoperative complications compared to the LD-NMB protocol. Despite these complications, the STA protocol did not cause a significant deleterious impact on post-operative outcomes as defined in the present study.

Onset and duration of action of escalating doses of atracurium in anesthetized healthy goats

OBJECTIVE

The aim of this study was to describe the onset and duration of action of escalating doses of atracurium in healthy, anesthetized goats.

STUDY DESIGN

Randomized, blinded, triple crossover study. Animals A total of eight (five males and three females) healthy goats weighing 42.7-123.5 kg and aged from 11 months to 8 years.

METHODS

Goats were anesthetized three times with propofol and anesthesia was maintained with isoflurane. One of three doses of atracurium was administered intravenously 30 minutes after induction: 0.25 mg kg-1 (AT25), 0.5 mg kg-1 (AT50) or 0.75 mg kg-1 (AT75). Acceleromyographic train-of-four ratio (TOFR) followed by train-of-four counts (TOFC) were recorded at 30 second intervals after atracurium administration to determine blockade onset (TOFC = 0). The TOFR followed by TOFC were recorded at 5 minute intervals until return to pre-atracurium baseline (TOFR = 1.0). Normally distributed data were analyzed with repeated measures anova and a Tukey multiple comparison test. Data not normally distributed were analyzed with a Friedman test and a Dunn's multiple comparison test.

RESULTS

For AT50 and AT75, 100% of goats achieved TOFC = 0 after atracurium administration. For AT25, however, 87.5% of goats achieved TOFC = 0 after atracurium administration. The onset time was shorter for AT75 [1.5 (0.5-1.5) minutes; median (range)] than for AT25 [2 (1-4) minutes] (p = 0.048). The duration of action [from onset time to complete reversal (TOFR = 1.0)] was significantly shorter for AT25 (52 ± 12 minutes, mean ± SD) than for AT50 (77 ± 18 minutes) (p < 0.001) and AT75 (85 ± 16 minutes) (p < 0.001). There was no significant difference in duration between AT50 and AT75 (p = 0.238).

CONCLUSIONS AND CLINICAL RELEVANCE

Doses of 0.5 and 0.75 mg kg-1 atracurium may produce complete neuromuscular blockade in healthy, anesthetized goats.

Sugammadex for reversal of moderate-to-deep rocuronium block in a clinical setting: A retrospective report of 10 dogs

OBJECTIVE

To compare recovery times of sugammadex with spontaneous recovery from rocuronium-induced neuromuscular block (NMB) in dogs.

STUDY DESIGN

Retrospective, unmatchedcase-control study.

ANIMALS

A total of 10 dogs administered sugammadex and 10 dogs recovering spontaneously from rocuronium-induced NMB.

METHODS

Files of dogs administered rocuronium between March and August 2023 were inspected. The train-of-four (TOF) count at the time of sugammadex administration and the time between administration and TOF ratio >90% (recovery time) were recorded. The recovery time for those not administered reversal agents was considered from the first TOF value >0 until TOF ratio >90%. The dose of sugammadex and the cumulative dose of rocuronium were recorded. Rocuronium doses and recovery times were compared using Mann-Whitney tests. The coefficient of determination (R2) between the cumulative rocuronium dose and sugammadex dose and the recovery time were calculated.

RESULTS

Dogs in the sugammadex and spontaneous recovery groups were administered intravenously (IV) 0.76 (0.4-2.6) and 0.61 (0.3-2.9) mg kg-1 of rocuronium, respectively (p = 0.325). Recovery time after 3.9 (2.9-5.5) mg kg-1 of sugammadex IV was 1 (1-3) minutes and was 20 (10-35) min for spontaneous recovery (p < 0.0001). The R2 for rocuronium and sugammadex doses and recovery times were 0.19 (p = 0.2) and 0.012 (p = 0.758).

CONCLUSIONS AND CLINICAL RELEVANCE

Sugammadex 2.9-5.5 mg kg-1 reversed moderate (TOF count 1-3) or deep (TOF count 0) rocuronium-induced NMB within 3 minutes, substantially faster than spontaneous recovery.

Generalised neuromuscular blockade after intraurethral administration of atracurium besilate in a male cat with urethral obstruction

A 4-year-old, entire, male, domestic long-haired cat was presented with an acute history of stranguria and dysuria and diagnosed with urolithiasis causing urethral obstruction. The patient was induced to general anaesthesia and several unsuccessful attempts to flush the uroliths retrogradely towards the bladder were made. An intraurethral administration of the neuromuscular blocking agent atracurium was performed as it has been reported to facilitate urethral catheterisation without any side effects. Respiratory arrest developed after 15 minutes from atracurium administration, which was promptly recognized and treated with mechanical ventilation. The absence of muscle contraction in response to a nerve stimulation confirmed a generalised muscle blockade. Approximately 35 minutes after, a muscle response to nerve stimulation appeared. Neostigmine combined with glycopyrrolate was administered resulting in complete recovery from neuromuscular blockade. In conclusion, the use of intraurethral atracurium can result in systemic absorption of the drug with subsequent generalised neuromuscular blockade.

Sugammadex for reversal of rocuronium-induced neuromuscular blockade during alfaxalone anesthesia in dogs

OBJECTIVE

To investigate the reversal effect of sugammadex on neuromuscular blockade induced by a single bolus of rocuronium in dogs under alfaxalone anesthesia.

STUDY DESIGN

Randomized, prospective, crossover experimental study.

ANIMALS

A group of six adult Beagle dogs (three females and three males), weighing 11.3-15.8 kg and aged 6-8 years, were used.

METHODS

Dogs were anesthetized twice with a 1.25 times minimum infusion rate of alfaxalone, with a washout period of at least 14 days between experiments. Neuromuscular function was monitored using acceleromyography with train-of-four (TOF) stimulation of the peroneal nerve. After recording the control TOF ratio (TOFRC), rocuronium (0.5 mg kg-1) was administered intravenously. Subsequently, sugammadex (4 mg kg-1) or an equal volume of saline (control treatment) was administered intravenously when the TOF count returned from 0 to 1 after neuromuscular blockade. Time from rocuronium injection to TOF count = 0 (onset time), time from TOF count = 0 to TOF count = 1 (maximum blockade period), time of first twitch amplitude recovery from 0.25 to 0.75 (recovery index), and time from sugammadex or saline administration to TOF ratio/TOFRC ≥ 0.9 (recovery time) were recorded.

RESULTS

The onset time and maximum blockade duration did not differ between sugammadex treatment [1.2 (0.7-1.5) minutes and 9.9 (6.3-10.5) minutes, respectively] and control treatment [median (range); 1.0 (0.7-1.1) minutes and 9.9 (8.8-11.5) minutes, respectively] (p = 0.219 and 0.844, respectively). Recovery index was 0.5 (0.3-0.7) minutes in sugammadex treatment, which was shorter than that in control treatment [4.5 (3.7-4.9) minutes] (p = 0.031). Recovery time was 0.8 (0.5-2.8) minutes in sugammadex treatment, which was shorter than that in control treatment [10.5 (6.8-14.3) minutes] (p = 0.031).

CONCLUSIONS AND CLINICAL RELEVANCE

Rocuronium-induced neuromuscular blockade was effectively reversed by sugammadex in dogs anesthetized with alfaxalone.

Evaluation of a three-axial acceleromyography monitor in dogs compared with mechanomyography

OBJECTIVE

To compare the ratio of the train-of-four (TOF) and double burst stimulation (DBS) obtained with three-axial acceleromyography (AMG) and mechanomyography (MMG) in dogs during recovery from a rocuronium-induced neuromuscular block.

STUDY DESIGN

Prospective, randomized, experimental study.

ANIMALS

A total of six intact healthy adult male Beagle dogs, weighing 9.1 ± 1.9 kg and aged 3-5 years.

METHODS

Dogs were anesthetized with intravenous (IV) dexmedetomidine and propofol, and isoflurane in oxygen. Neuromuscular function was measured with AMG and MMG in the contralateral thoracic limbs. Rocuronium (0.5 mg kg-1) was administered IV, and the TOF and DBS ratios measured. During neuromuscular block offset, MMG values were recorded when AMG first reached ratios of 0.9 and 1.0. True recovery from neuromuscular block was determined as MMG ratio ≥ 0.9. The false-positive (AMG ≥ 0.9 or 1.0, and MMG ratio < 0.9) rate was determined. Paired values were compared, and bias and limits of agreement were calculated. Receiver operating characteristic (ROC) curves were created.

RESULTS

When AMG first reached 0.9 and 1.0 during recovery, MMG values were lower (p < 0.040). When AMG reached 0.9, the false-positive rate was 29% with TOF and 27% with DBS. It decreased to 12% (TOF) and 11% (DBS) when a ratio of 1.0 was used. AMG values were higher than paired MMG values (p < 0.001). The AMG overestimated MMG by 24% and 22% for TOF and DBS, respectively. Areas under the ROC curves (95% confidence interval) were 0.91 (0.89, 0.94) and 0.86 (0.81, 0.94) for TOF and DBS, respectively.

CONCLUSIONS

and clinical relevance The three-axial AMG monitor overestimated neuromuscular function and, in some cases, indicated adequate recovery despite the MMG ratio being < 0.9. A TOF or DBS ratio of at least 1.0 should be considered when monitoring recovery of neuromuscular block with this AMG device.

Duration of neuromuscular block is more variable and recovery time is shorter with rocuronium than cisatracurium in anesthetized dogs

OBJECTIVE

To compare the variability in the duration of action of a single dose of rocuronium or cisatracurium, and duration of subsequent top-up doses in anesthetized dogs.

ANIMALS

Thirty dogs requiring ophthalmic surgery with neuromuscular block.

PROCEDURES

Neuromuscular function was monitored with train-of-four (TOF) and acceleromyography. Dogs received an initial dose of rocuronium 0.6 mg/kg, or cisatracurium 0.15 mg/kg IV, which produced complete neuromuscular block. Upon return of the first response (T1) of TOF, a third of the initial dose was repeated. The duration of the initial dose and its variability were compared between agents. Duration of subsequent top-up doses was assessed with mixed effect models. Spontaneous (from last return of T1) or neostigmine-enhanced (from administration to complete recovery) recovery times were measured for each agent.

RESULTS

Duration of action of the initial dose was [median (range)] 25 (10-60) min with rocuronium and 35 (15-45) min with cisatracurium (p = .231). The variability of rocuronium was 3.25 times larger than cisatracurium (p = .034). Duration of top-up doses did not vary for either agent. Spontaneous recovery was shorter for rocuronium [15 (10-20) min] than cisatracurium [25 (15-45) min] (p = .02). Neostigmine-enhanced recovery times were 5 (5-25) for rocuronium and 10 (5-10) for cisatracurium (p = .491).

CONCLUSIONS

Duration of action for a single dose is significantly more variable with rocuronium than cisatracurium. Time to spontaneous recovery was longer for cisatracurium, and cases of unexpectedly long recovery times were observed with both agents. Objective monitoring is recommended.

Neuromuscular blockade effects of cisatracurium in 11 cats undergoing ophthalmological surgery anaesthetised with isoflurane

CASE SERIES SUMMARY

This case series describes the neuromuscular blockade (NMB) following 0.15 mg/kg intravenous (IV) cisatracurium administration in 11 cats undergoing ophthalmological surgery and anaesthetised with isoflurane. Anaesthetic records were analysed retrospectively. Neuromuscular function was assessed by a calibrated train-of-four (TOF) monitor. Cats were 73 ± 53 months old, weighed 4 ± 1 kg and were of American Society of Anesthesiologists' physical classification 2. Duration of anaesthesia and surgery were 144 ± 27 and 94 ± 24 mins, respectively. The lowest TOF count was zero in four cats, four in six cats and for one cat the TOF ratio never decreased below 31%. The time of onset was between 1 and 6 mins after the administration of cisatracurium and the mean duration of action was 20.4 ± 10.1 mins.

RELEVANCE AND NOVEL INFORMATION

Cisatracurium at a dose of 0.15 mg/kg IV did not consistently induce a TOF count of zero in all cats. The dose used in these cats did not produce any remarkable cardiovascular side effects. Although the NMB was not complete, the dose given was sufficient to produce central eyeball position, which was the goal of the ophthalmic surgeries.

Effects of two levels of partial neuromuscular block with atracurium on the ventilatory response to hypercapnia in anesthetized Beagles

OBJECTIVE To evaluate effects of 2 levels of partial neuromuscular block on the ventilatory response to a hypercapnic challenge in anesthetized dogs and to evaluate effects of edrophonium for reversing partial neuromuscular block. ANIMALS 6 healthy adult Beagles. PROCEDURES Each dog was anesthetized twice with propofol and dexmedetomidine. End-tidal partial pressure of CO₂ (Petco₂), tidal volume (Vt), and peak inspiratory flow (PIF) were measured during breathing at rest. Maximal Vt and PIF (Vt_MAX and PIF_MAX, respectively) in response to a hypercapnic challenge consisting of 10% CO₂ inhaled for 1 minute were measured. Variables were measured before administration of atracurium (baseline), during moderate (train-of-four [TOF] ratio, 0.3 to 0.5) and mild (TOF ratio, 0.6 to 0.8) atracurium-induced neuromuscular block, and after neuromuscular block recovery (TOF ratio, ≥ 0.9) following administration of edrophonium or saline (0.9% NaCl) solution. Dogs for which any variable returned to < 80% of the baseline value were identified. RESULTS Partial neuromuscular block increased Petco₂; it impaired Vt at rest and Vt_MAX but not PIF at rest and PIF_MAX. All variables except Petco₂ returned to baseline values when the TOF returned to ≥ 0.9. After recovery from neuromuscular block, significantly more dogs had a Vt_MAX < 80% of the baseline value when edrophonium was not administered. CONCLUSIONS AND CLINICAL RELEVANCE Partial neuromuscular block in anesthetized Beagles decreased spontaneous ventilation at rest and impaired the response to a hypercapnic challenge. Response to hypercapnic challenge might remain partially impaired after recovery of the TOF ratio to ≥ 0.9.

Evaluation of neostigmine antagonism at different levels of vecuronium-induced neuromuscular blockade in isoflurane anesthetized dogs

Residual neuromuscular block (NMB) during recovery from general anesthesia may be minimized by antagonizing NMB with neostigmine. We examined neostigmine for restoring neuromuscular function when administered at 2 levels of vecuronium-induced NMB in dogs. Eight healthy adult dogs received vecuronium 0.1 mg/kg body weight (BW), IV, during isoflurane anesthesia. Recovery from vecuronium occurred spontaneously (control group; C), or was enhanced with neostigmine, 0.04 mg/kg BW, IV, administered when 2 (N2) or 4 (N4) responses to train-of-four (TOF) stimulation were first observed. Duration of NMB was significantly shorter for N2 and N4 than for C. The period of complete NMB was equal for all groups; differences were observed during the recovery phase of NMB. Time of neostigmine-enhanced recovery was significantly shorter for N4 than N2, but overall duration of NMB was not reduced. Recovery from NMB was faster with neostigmine. There is no clinical advantage in delaying neostigmine administration once 2 responses to TOF are present.

Use of rocuronium administered by continuous infusion in dogs

OBJECTIVE

A clinical trial to determine whether continuous infusion administration technique was suitable for maintaining neuromuscular blockade with rocuronium bromide in dogs.

ANIMALS

Twenty-two dogs, 10 males and 12 females, median age 2 years 4 months, median weight 32 kg undergoing elective surgical procedures under general anaesthesia: ASA classification I or II.

MATERIALS AND METHODS

After induction of anaesthesia, neuromuscular function was evaluated using train-of-four (TOF) stimulation of the dorsal buccal branch of the facial nerve. A bolus dose of 0.5 mg kg(-1) rocuronium was administered intravenously and an infusion of 0.2 mg kg(-1) hour(-1) was started immediately. Neuromuscular blockade was assessed visually by counting the number of twitches observed during TOF stimulation repeated at 10-second intervals.

RESULTS

The bolus dose of rocuronium abolished the response to TOF stimulation in 21 of the 22 dogs. The median onset time of neuromuscular blockade (complete loss of all four twitches) was 82 seconds (range 38-184 seconds). Median infusion duration was 76 minutes (range 20.3-146 minutes).

CONCLUSIONS AND CLINICAL RELEVANCE

This protocol of rocuronium administration was considered to be effective in dogs. Constant infusion of rocuronium is easily applicable to clinical practice and further work is required on infusion titration.

Observations on the muscle relaxant rocuronium bromide in the horse – a dose–response study

OBJECTIVE

To investigate the onset and duration of neuromuscular blockade of rocuronium bromide and its associated haemodynamic effects at three doses in healthy horses.

STUDY DESIGN

Prospective, randomized experimental study.

ANIMALS

Seven adult horses aged 3-20 (mean 10.3) years and weighing 466 +/- 44 (mean +/- SD) kg.

METHODS

Horses were anaesthetized three times with at least 2 weeks between. They were pre-medicated with 0.6 mg kg(-1) xylazine and 0.01 mg kg(-1) butorphanol i.v.. Anaesthesia was induced with 2.2 mg kg(-1) ketamine and 0.1 mg kg(-1) diazepam i.v.. Following orotracheal intubation anaesthesia was maintained with isoflurane in 100% oxygen. Intermittent positive pressure ventilation was initiated and the horses were ventilated at a respiratory rate (fr) of 4-8 breaths minute(-1). Neuromuscular function was monitored with an acceleromyograph. The peroneal nerve was stimulated with train-of-four (TOF) mode at 2 Hz every 15 seconds. Each horse received, in randomly assigned order, one of the three doses of rocuronium: 0.2 mg kg(-1) (D02), 0.4 mg kg(-1) (D04) or 0.6 mg kg(-1) (D06) i.v.. Lag time, onset time, time of no response, duration of action and the TOF ratio 0.7 and 0.9 were measured. Recovery time (T1(25-75)) was calculated. Vital parameters were recorded at 5-minute intervals on a standard anaesthetic record form.

RESULTS

Rocuronium produced a dose-dependent duration of action in isoflurane-anaesthetized horses. 100% block was observed in D04 and D06 but not in D02, in which the maximum decrease of the first twitch of TOF attained was 91.5 +/- 16.5%. Time to T1(25) was 13.1 +/- 5.5 minutes, 38.6 +/- 10.1 minutes and 55 +/- 9.8 minutes in D02, D04 and D06 respectively. There was a significantly shorter time for TOFR 0.9 with 0.2 mg kg(-1) compared with 0.4 and 0.6 mg kg(-1) rocuronium. T1(25-75) in D04 and D6 was not statistically significantly different. Heart rate, systolic, diastolic and mean arterial blood pressure increased slightly during the observation period.

CONCLUSION

Rocuronium is an effective nondepolarizing muscle relaxant in horses under isoflurane anaesthesia. It had a dose-dependent onset and duration of action. Rocuronium did not produce significant changes in the measured cardiovascular parameters.

A clinical study of the effects of rocuronium in isoflurane-anaesthetized cats

OBJECTIVE

To evaluate the neuromuscular blocking and chronotropic effects of rocuronium bromide in cats anaesthetized for surgery.

STUDY DESIGN

Prospective clinical trial.

ANIMALS

Twenty-two healthy cats of mixed breed presented for ovariectomy (n = 13) or castration (n = 9). Mean body mass (+/-SD) was 3.6 +/- 0.65 kg and mean age was 10.25 +/- 2.63 months.

METHODS

Anaesthesia was induced with intravenous (IV) midazolam (0.3 mg kg(-1)), ketamine (3 mg kg(-1)) and butorphanol (0.4 mg kg(-1)). Tracheal intubation was performed and anaesthesia was maintained with isoflurane delivered in 100% oxygen. Neuromuscular function was monitored using acceleromyography applied at the ulnar nerve. This was stimulated by using the train-of-four (TOF) stimulus pattern (2 Hz) delivered every 15 seconds. The first train was made to establish baseline values for the first twitch (T1) and the TOF-ratio (T4:T1). Rocuronium (0.6 mg kg(-1) IV) was given and the following periods were recorded beginning at the end of injection: (1) lag time (LT) - to the first signs of T1 depression; (2) onset time (OT) - to the total ablation of T1; (3) duration of action (T1(25)) - to 25% recovery of the baseline value for T1; (4) T1(50)- to 50% baseline T1 restoration; (5) to TOF-ratios of 0.7 and 0.9. The time taken for T1 to recover from 75% to 25% depression (T1(25-75)) was also recorded. Heart rate (HR) was taken every minute for 15 minutes, beginning 5 minutes before rocuronium was injected.

RESULTS

Rocuronium (0.6 mg kg(-1)) had a mean LT of 15.0 +/- 0 seconds, OT of 46 +/- 11 seconds and T1(25) of 13.2 +/- 2.7 minutes. The mean time for TOF 0.7 and 0.9 was 17.3 +/- 5.4 and 20.7 +/- 5.4 minutes respectively. The mean T1(25-75) was 4.8 +/- 2.4 minutes. No significant changes in HR were observed at any of the time intervals recorded.

CONCLUSION

Rocuronium is an effective nondepolarizing muscle relaxant in the cat under the clinical conditions of this study. It has a rapid onset, a short duration of action and did not cause significant changes in HR.

Neuromuscular blocking properties of atracurium during sevoflurane or propofol anaesthesia in dogs

OBJECTIVE

To quantify the neuromuscular blockade (NMB) produced by atracurium in either sevoflurane or propofol-anaesthetized dogs.

ANIMALS

Twelve healthy, female adult mixed-breed dogs weighing 13 +/- 3 kg (range 10-22 kg).

MATERIALS AND METHODS

Three doses of atracurium (0.1, 0.2 and 0.3 mg kg(-1)) were tested at 1-week intervals. Anaesthesia was induced with inhaled sevoflurane or intravenous propofol and maintained with end-tidal sevoflurane concentrations of 1.95% (1.25 x MAC) or propofol 0.6 mg kg(-1) minute(-1) respectively. Acceleromyography and train-of-four stimulation of the fibular nerve were used for the assessment of NMB. The percentage depression of the first twitch (T1) and the fourth to the first twitch ratio (T4/T1), the maximum degree of neuromuscular block achieved and surgical muscle relaxation were recorded. Before and during neuro muscular blockade (at 10 minute intervals) body temperature, ECG, arterial blood pressure, inspired and expired CO2 concentrations and SpO2 were recorded.

RESULTS

Atracurium produced a dose-dependent duration of NMB in both propofol and sevoflurane-anaesthetized dogs. Duration of block was longer in dogs anaesthetized with sevoflurane. All studied doses of atracurium caused twitch depression > or =95% with little or no cardiovascular changes.

CONCLUSIONS

Sevoflurane produces a clinically relevant potentiation of atracurium-induced NMB in dogs compared with propofol.

CLINICAL RELEVANCE

Significant differences in the potentiation of NMB drugs are encountered with commonly used anaesthetics in the dog.

Use of rocuronium for endotracheal intubation of North American Gulf Coast box turtles

OBJECTIVE

To determine whether rocuronium, a reversible neuromuscular blocking agent, would provide safe, short-term immobilization to facilitate endotracheal intubation in turtles.

DESIGN

Prospective study.

ANIMALS

30 healthy adult Gulf Coast box turtles.

PROCEDURE

Turtles were given rocuronium, and responses were recorded every 3 minutes. Times to onset of effects, intubation, and recovery were recorded and analyzed for associations with dose and patient characteristics to determine an optimal dose range. Neostigmine and glycopyrrolate were given to augment recovery from neuromuscular blockade.

RESULTS

Rocuronium administered at a dose of 0.25 to 0.5 mg/kg (0.11 to 0.23 mg/lb), IM, permitted intubation; lower doses were not effective. Mean +/- SD time to loss of the palpebral reflex was 6.4 +/- 4.0 minutes, and mean time to intubation was 9.2 +/- 6.4 minutes. Mean time to return of the palpebral reflex was 44 +/- 13.2 minutes, and mean time to walking was 55 +/- 16.6 minutes. Time to onset of effects was not associated with dose, but recovery times were prolonged with higher doses of rocuronium. Cardiac arrhythmias were observed in 13 (43%) turtles.

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of rocuronium at a dose of 0.25 to 0.5 mg/kg is a safe and effective adjunct to general anesthesia in Gulf Coast box turtles. Because rocuronium does not provide any analgesic or sedative effects, the duration of neuromuscular blockade without anesthesia should be minimized to avoid undue distress.