Use of rocuronium administered by continuous infusion in dogs

Quantitative evaluation of the biomechanical and viscoelastic properties of the dog patellar tendon in response to neuromuscular blockade at different stifle angles

The patellar tendon (PT) is crucial for maintaining stability and facilitating movement in the stifle joint. Elastography has been recognized as a prominent method for evaluating PT properties in humans and dogs. The utilization of oscillation methods in canine studies remains limited despite their extensive documentation in human studies. Our study represents the first effort to quantitatively assess and compare the effects of muscle relaxant on the biomechanical and viscoelastic characteristics of the PT at varying stifle angles in living dogs. Five healthy female beagles were used in this study. Biomechanical (tone, stiffness, and decrement) and viscoelastic (relaxation time and creep) properties of the PT were measured using MyotonPRO (Myoton Ltd, Estonia) prior to and following administration of rocuronium (0.5 mg/kg/body weight) at normal, extended, and flexed positions. Rocuronium was selected for its safety, controllability, and widespread clinical use in veterinary anesthesia. Two-way analysis of variance showed that tone, stiffness, and decrement were significantly higher (P < 0.001) in the control group than in the muscle relaxation group. At the same time, relaxation time and creep were significantly lower (P < 0.001) in the control group than in the muscle relaxation group. The findings indicate that stifle angle position and muscle rexalant administration fundamentally alter the biomechanical loading conditions of the PT, leading to changes in its viscoelastic properties. Therefore, this novel quantitative data could benefit clinical settings that necessitate accurate and objective methods for risk identification and monitoring PT biomechanics in dogs.

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.

ED50 and ED95 of rocuronium during alfaxalone anesthesia in dogs

OBJECTIVE

To determine the median effective dose (ED₅₀) and effective dose required to depress the twitch value by 95% (ED₉₅) of rocuronium during alfaxalone anesthesia in dogs.

STUDY DESIGN

A randomized, prospective, crossover experimental study.

ANIMALS

A total of eight adult Beagle dogs (four female, four male), weighing 10.3-14.6 kg and aged 6-8 years.

METHODS

The dogs were anesthetized three times with 1.25-fold the individual minimum infusion rate of alfaxalone at intervals of ≥ 14 days. Neuromuscular function was monitored with train-of-four (TOF) stimulation of the peroneal nerve by acceleromyography. After recording the control TOF ratio (TOFRC) and first twitch of TOF (T1C), a single bolus dose of rocuronium 100, 175 or 250 μg kg^-1 (treatments R100, R175 or R250) was administered intravenously. The maximum suppression of the first twitch of TOF (T1) was recorded and calibrated with T1C to construct the dose-response curve, from which ED₅₀ and ED₉₅ were calculated. Time from rocuronium administration to TOF ratio/TOFRC > 0.9 (duration TOFR0.9) was recorded.

RESULTS

ED₅₀ and ED₉₅ of rocuronium during alfaxalone anesthesia were 175 and 232 μg kg^-1, respectively. The median (range) duration TOFR0.9 was longer in treatment R250 [10.1 (9.2-10.9) minutes] than in treatments R100 [3.1 (2.9-4.4) minutes; p < 0.0001] and R175 [7.7 (6.9-8.1) minutes; p < 0.0001]; and longer in treatment R175 than in treatment R100 (p < 0.0001).

CONCLUSIONS AND CLINICAL RELEVANCE

The duration of TOFR0.9 correlated positively with the dosage of rocuronium, indicating that recovery time of rocuronium was also dose-dependent in dogs anesthetized with alfaxalone. The duration TOFR0.9 of rocuronium 250 μg kg^-1 was 10 minutes during alfaxalone anesthesia in dogs.

Effects of sevoflurane, propofol or alfaxalone on neuromuscular blockade produced by a single intravenous bolus of rocuronium in dogs

OBJECTIVE

To compare the effects of sevoflurane, propofol and alfaxalone on the neuromuscular blockade induced by a single intravenous bolus of rocuronium in dogs.

STUDY DESIGN

A randomized, prospective, crossover experimental study.

ANIMALS

A total of eight adult Beagle dogs (four female, four male), weighing 8.9-15.3 kg and aged 5-7 years.

METHODS

The dogs were anesthetized three times with 1.25× minimum alveolar concentration of sevoflurane (SEVO treatment) and 1.25× minimum infusion rate of propofol (PROP treatment) or alfaxalone (ALFX treatment) at intervals of ≥14 days. Neuromuscular function was monitored with train-of-four (TOF) stimulation of the peroneal nerve by acceleromyography. After recording the control TOF ratio (TOFRC), a single bolus dose of rocuronium (1 mg kg^-1) was administered intravenously. The times from rocuronium administration to achieving TOF count 0 (onset time), from achieving TOF count 0 to the reappearance of TOF count 4 (clinical blockade period), from 25% to 75% of TOFRC (recovery index) and from achieving TOF count 0 to TOF ratio/TOFRC >0.9 (total neuromuscular blockade duration) were recorded.

RESULTS

The onset time and recovery index did not differ among the treatments. The median clinical blockade period was longer in the SEVO treatment [27.3 (26.0-30.3) minutes] than in PROP [16.6 (15.4-18.0) minutes; p = 0.002] and ALFX [22.4 (18.6-23.1) minutes; p = 0.017] treatments; and longer in the ALFX treatment than in the PROP treatment (p = 0.020). The mean total neuromuscular blockade duration was longer in the SEVO treatment (43.7 ± 9.9 minutes) than in PROP (25.1 ± 2.7 minutes; p < 0.001) and ALFX (32.5 ± 8.4 minutes; p = 0.036) treatments.

CONCLUSIONS AND CLINICAL RELEVANCE

Compared with alfaxalone and propofol, sevoflurane prolonged rocuronium-induced neuromuscular blockade by a significantly greater extent in dogs.

Effect of sevoflurane anesthesia on neuromuscular blockade produced by rocuronium infusion in dogs

This study evaluated the effect of sevoflurane anesthesia on neuromuscular blockade with rocuronium in dogs. Six healthy beagle dogs were anesthetized four times with a minimum 14-day washout period. On each occasion, the dogs were administered 1.25-, 1.5-, 1.75-, or 2.0-fold of the individualized minimum alveolar concentration (MAC) of sevoflurane and received an infusion of rocuronium (0.5 mg/kg followed by 0.2 mg/kg/hr) for 120 min. Neuromuscular function was monitored with acceleromyography and train-of-four (TOF) stimulation of the left hind limb. Time to achieve TOF count 0 (onset time), time from the onset of neuromuscular blockade to the reappearance of TOF count 4 (blockade period), and time from the onset of rocuronium infusion to attaining a 70 or 90% TOF ratio (TOFR₇₀ or TOFR₉₀) were recorded. There were no significant differences in the onset time, blockade period, and plasma rocuronium concentration between the sevoflurane MAC multiples. The TOFR₇₀ and TOFR₉₀ were dose-dependently prolonged with the sevoflurane MAC multiples. There were significant differences in the TOFR₇₀ and TOFR₉₀ between the 1.25 sevoflurane MAC (median: 55 and 77.5 min, respectively) and 1.75 sevoflurane MAC (122.0 and 122.6 min; P=0.020 and P=0.020, respectively), 1.25 sevoflurane MAC and 2.0 sevoflurane MAC (126.0 and 131.4 min; P=0.020 and P=0.020), and 1.5 sevoflurane MAC (97.5 and 121.3 min) and 2.0 sevoflurane MAC (P=0.033 and P=0.032). In dogs, sevoflurane anesthesia produced dose-dependent prolongation of recovery from neuromuscular blockade produced by rocuronium.

Monitoring of intense neuromuscular blockade in a pig model

Intense neuromuscular blockade (NMB) measured by post tetanic count (PTC) was monitored, reversed and verified in this pig model. In a cross-over assessor blinded design six pigs were randomized to either no NMB followed by intense NMB, or intense NMB followed by no NMB. Neuromuscular measurements were performed with acceleromyography [train-of-four (TOF) Watch SX]. In all pigs, the response to TOF nerve stimulation was stable and intense NMB (PTC 0-1) was established with rocuronium 3 mg/kg. For reversal, the pigs received sugammadex 20-35 mg/kg and returned to TOF-ratio above 0.90 within 2.15 min after injection. We established a pig model for monitoring intense NMB with surface stimulation electrodes and acceleromyography. We verified total relaxation of the diaphragm and the abdominal muscles at the PTC 0-1 by suction test and with surface electromyography. This pig model is suitable for studies with experimental abdominal surgery with monitoring of intense NMB, and where relaxation of the diaphragm and the abdominal muscles are required.

Effects of rocuronium bromide on globe position and respiratory function in isoflurane-anesthetized dogs: a comparison between three different dosages

OBJECTIVE

To evaluate the effect on globe position and respiration of three dosages of intravenous rocuronium in isoflurane-anesthetized dogs.

ANIMAL STUDIED

Thirty-two dogs anesthetized for ophthalmic procedures.

PROCEDURES

The dogs were divided into four groups, each of eight animals (G1-G4). G1, G2, G3 received 0.075, 0.05, 0.03 mg/kg of IV rocuronium, respectively; G4 received 0.9% NaCl IV; all the treatments were administered when an end-tidal isoflurane of 1.1-1.2% was reached. Anesthesia was obtained with dexmedetomidine (2.5 mcg/kg IV), methadone (0.1 mg/kg IV), propofol (2 mg/kg IV), and isoflurane in oxygen. Neuromuscular function was assessed with acceleromyography by stimulation of the peroneal nerve using the train-of-four (ToF) and the ToF ratio (ToFR). Monitoring of cardiovascular and respiratory functions was performed. Changes in globe position were recorded.

RESULTS

All three dosages of rocuronium produced centralization of the globe. Duration was 24.3 ± 4.2, 23.4 ± 3.6, and 8.7 ± 2.8 min, for G1, G2, and G3, respectively. The control group did not show globe centralization. No significant differences were found among the four groups in cardiovascular and respiratory parameters. Minute volume and ToFR were significantly lower in G1 compared with baseline values.

CONCLUSIONS

All doses of rocuronium resulted in globe centralization. The higher dose provoked a transient respiratory depression and some degree of skeletal muscular blockade detectable with ToFR. No alterations in respiratory activity were present when 0.05 mg/kg was used. The 0.03 mg/kg dosage could be useful for very short ophthalmic procedures.

The post-tetanic count during vecuronium-induced neuromuscular blockade in halothane-anaesthetized dogs

OBJECTIVE

To evaluate the post-tetanic count (PTC) for predicting the return of reversible neuromuscular blockade at the n. facialis-m. nasolabialis (nF-mNL) and n. ulnaris-mm. carpi flexorii (nU-mCF) nerve-muscle units (NMUs) during profound vecuronium neuromuscular blockade in halothane-anaesthetized dogs.

STUDY DESIGN

Randomized, prospective, experimental study.

ANIMALS

Twenty-five dogs (seven male 18 female) undergoing surgery; mean age: 4.8 years; mean body weight 22 kg.

METHODS

Thirty minutes after acepromazine (0.05 mg kg(-1)) and morphine (0.5 mg kg(-1)) pre-medication, anaesthesia was induced with intravenous (IV) thiopental and maintained with halothane, N(2)O and O(2). The lungs were mechanically ventilated and end-tidal halothane concentration (Fe'(HAL)) maintained at 1.04%. Neuromuscular transmission was monitored using the train-of-four count (TOFC) at one nF-mNL and both nU-mCF units. Vecuronium (50 microg kg(-1) IV) was injected after 15 minutes constant Fe'(HAL). When the first twitch (T1) at both nU-mCF units had disappeared (t = 0) one (randomly allocated) ulnar nerve was stimulated every 5 minutes using PTC; TOF stimulation continued at the other sites. The PTC was plotted against the interval between recording time and T1's reappearance at the other NMUs.

RESULTS

At t = 0, the mean PTC in the contralateral nU-mCF unit was 18 (range 0-20). Mean PTC was a minimum at t = 5, rising to the maximum (20) at 25 minutes. Six dogs were vecuronium-resistant as monitored by PTC. Excluding data from these revealed a strong negative relationship between ulnar PTC and the time taken for T1's return at the facial (r = -0.7018; p < 0.00001) and contralateral ulnar (r = -0.8409; p < 0.00001) NMUs.

CONCLUSION AND CLINICAL RELEVANCE

Post-tetanic count monitoring beginning >5 minutes after the TOFC at nU-mCF = 0 provided a reliable estimate of T1's return at ulnar and facial NMUs.