Bias, limits of agreement, and percent errors between acceleromyography and mechanomyography in anesthetized dogs

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.

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.

The train-of-four or double-burst ratios cannot reliably exclude residual neuromuscular block in cats

This study investigated the relationship between train-of-four (TOF) or double burst (DBS) ratios (T4:T1 or B2:B1) and twitch (T1) or burst (B1) magnitudes during the recovery from rocuronium-induced neuromuscular block in dogs and cats. The main hypothesis was that TOF or DBS ratios recover after the recovery of T1 or B1, and hence high ratio levels are sensitive indicators of restoration of the neuromuscular function. Six anesthetized dogs and six anesthetized cats received 0.5 mg/kg of rocuronium intravenously. The amplitudes of T1 or B1 were measured with mechanomyography during neuromuscular block until the neuromuscular function recovered fully. The TOF or DBS ratio was recorded concurrently. In dogs, recovery of T1 and B1 preceded the recovery of the TOF and DBS ratios, and T1 and B1 were always ≥90% of recovery when the respective ratio reached 0.9. In contrast, T1 was still depressed in 5/6 cats when the TOF ratio reached 0.9. At that moment, T1 was 72.5 ± 19.8% of recovery. Similarly, the DBS ratio returned to 0.9 when B1 was still <90% in 3/6 cats of recovery. The TOF and DBS fade in dogs consistently disappeared after the magnitude of T1 or B1 were restored, and hence, ratios ≥0.9 are a sensitive indicator that the neuromuscular function recovered. Our observation in cats however show that the spontaneous recovery of neither the TOF nor the DBS ratio of 0.9 can reliably exclude residual block, as the magnitude of T1 or B1 was still depressed in several instances.

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.