Onset of rocuronium-induced neuromuscular block evaluated subjectively and accerelomyographically at the masseter muscle.

PURPOSE: The main aim of this study was to compare the onset times of rocuronium evaluated subjectively and by acceleromyography at the masseter muscle (MM). METHODS: Forty female patients were sequentially enrolled in this study. In the first 20 patients, neuromuscular block was evaluated subjectively. After induction of anesthesia with fentanyl and propofol, both the left masseter and ulnar nerves were stimulated in 2-Hz train-of-four (TOF) mode using peripheral nerve stimulators. Contractions of the MM were felt with an anesthesiologist's left hand holding an anesthesia facemask; those of the adductor pollicis (APM) were visually observed. All the patients received a bolus of rocuronium, 0.6 mg/kg. Onset times after rocuronium were defined as the duration until the contractions became impalpable at the MM or invisible at the APM. At the time contraction of the MM had not been felt, intubating conditions were assessed. In the next 20 patients, contractions of the MM and the APM were concurrently quantified using acceleromyography after induction of anesthesia and laryngeal mask insertion. Following 0.6 mg/kg rocuronium, onset of the action was recorded. RESULTS: Onset of the action of rocuronium at the MM evaluated subjectively [mean (SD), 70.3 (17.7) s] was similar to that monitored acceleromyographically [73.3 (27.6) s, P > 0.05], and significantly shorter than that at the APM acceleromyographically [111.0 (34.8) s, P = 0.016]. Intubating conditions of 20 patients were graded either excellent or good. CONCLUSION: Subjective evaluation of contractions of the MM by an anesthesiologist's hand may be reliable to determine faster timing for safe tracheal intubation.

A randomized trial to identify optimal precurarizing dose of rocuronium to avoid precurarization-induced neuromuscular block.

PURPOSE: The aim of this study was to examine the safe precurarizing dose of rocuronium required to avoid neuromuscular block after precurarization. METHODS: Twenty-four female patients were randomly allocated into two groups of 12 patients each. General anesthesia was induced and maintained with remifentanil and propofol, and a laryngeal mask was inserted without the aid of a neuromuscular blocking agent. Patients were randomized to receive either 0.03 or 0.06 mg/kg rocuronium as a precurarizing dose. Neuromuscular block was monitored using acceleromyographic train-of-four (TOF) of the adductor pollicis muscle. Three minutes after the precurarization, all patients received suxamethonium 1.5 mg/kg and were graded on severity of fasciculations. RESULTS: The average TOF ratio was kept above 0.9 even 3 min after precurarization with 0.03 mg/kg rocuronium. In contrast, in patients who received 0.06 mg/kg rocuronium, the ratios significantly decreased to 0.72 (0.14) [mean (SD), P < 0.004] and 0.68 (0.18) (P < 0.006) 2 min and 3 min after the precurarization, respectively. No visible muscle movement was observed following suxamethonium injection, except that one patient who received 0.03 mg/kg rocuronium showed very fine muscle movements of the fingertips. CONCLUSION: Rocuronium at 0.06 mg/kg is an overdose for precurarization. The results of the present study demonstrate that a safe and effective precurarizing dose of rocuronium is 0.03 mg/kg.

[Optimum intubating dose of rocuronium for short duration surgery in adult patients].

BACKGROUND: The aim of this study was to examine optimum intubating dose of rocuronium in adult patients who had been scheduled for short duration surgery. METHODS: Thirty patients were randomly assigned to receive rocuronium 0.4 mg x kg(-1), 0.5 mg x kg(-1) or 0.6 mg x kg(-1) during induction with propofol and fentanyl. Immediately after the adduction of thumb to the ulnar nerve stimulation could not be visually observed, the patients were intubated tracheally and the intubating conditions were evaluated. Thereafter, time to recover to train-of-four (TOF) counts of 4 was recorded during sevoflurane and nitrous oxide anesthesia. RESULTS: Intubating conditions after rocuronium 0.5 and 0.6 mg x kg(-1) were all graded either excellent or good. In contrast, inadequate conditions for safe and easy tracheal intubation were observed in 60% of the patients receiving 0.4 mg x kg(-1). Time to spontaneous recover to the TOF counts of 4 correlated with the intubating doses of rocuronium. CONCLUSIONS: For short duration surgeries, rocuronium 0.5 mg x kg(-1) was appropriate to perform safe tracheal intubation and minimize duration of action of rocuronium.

Effectiveness of the timing principle with high-dose rocuronium during rapid sequence induction with lidocaine, remifentanil and propofol.

PURPOSE: The main purpose of this study was to examine the effectiveness of the timing principle with 1 mg kg(-1) rocuronium for rapid sequence intubation. As secondary outcomes, propofol and lidocaine with or without remifentanil were examined to note their effects on the cardiovascular responses to laryngoscopy and intubation. METHODS: Thirty patients were randomly allocated to one of two groups of 15 patients each: a lidocaine-treated group (L) and a lidocaine/remifentanil-treated group (LR). Thirty seconds after lidocaine 1 mg kg(-1) with or without infusion of remifentanil 1 microg kg(-1) min(-1), all patients received a bolus of rocuronium 1 mg kg(-1). Shortly afterwards, patients were given propofol 2-2.5 mg kg(-1). Intubating conditions and cardiovascular responses were observed 60 s after rocuronium. The time to spontaneous recovery of visible train-of-four (TOF) counts of 4 was observed at the thumb during 1.0-1.5% end-tidal sevoflurane and remifentanil anesthesia. RESULTS: All patients had excellent or good intubating conditions. Hypertension and tachycardia during laryngoscopy were well prevented in group LR, whereas they were significantly observed in group L. The times to reappearance of TOF counts of 4 were comparable in all groups [mean (SD); 63.6 (8.6) min in group L and 63.5 (11.6) min in group LR]. CONCLUSION: Application of the timing principle with 1 mg kg(-1) rocuronium is beneficial for rapid tracheal intubation. Co-administered lidocaine, remifentanil and propofol can definitely suppress cardiovascular responses during laryngoscopy and intubation.

Effect of landiolol hydrochloride on suxamethonium-induced neuromuscular block.

PURPOSE: The aim of this study was to examine the effect of landiolol hydrochloride, an ultrashort-acting beta(1)-blocker, on suxamethonium-induced neuromuscular block. METHODS: Thirty patients were randomly allocated to receive a loading dose of landiolol, 0.125 mg x kg(-1) x min(-1) for 1 min, followed by an infusion at 0.04 mg x kg(-1) x min(-1), or placebo. Twenty minutes after the infusion of landiolol or placebo, suxamethonium 1 mg x kg(-1) was administered during propofolfentanyl-nitrous oxide anesthesia. Neuromuscular block was monitored by train-of-four (TOF) responses of the adductor pollicis muscle, applying acceleromyographic stimuli to the ulnar nerve. RESULTS: The onset of neuromuscular block did not differ between the groups. The time from administration of suxamethonium to spontaneous recovery to the first twitch of TOF (T1) of control was significantly longer in the landiolol group (mean [SD]; 12.2 [2.5] min), when compared with the control group (9.8 [2.6] min). However, the TOF ratios measured when the T1 had spontaneously recovered to 10%, 25%, 50%, 75%, 90%, and 100% of control was comparable between the groups. CONCLUSION: Landiolol delayed recovery from suxamethonium-induced paralysis. However, the interaction between the drugs seemed to be small in the clinical setting.

[Investigations into neostigmine-induced inhibition of neuromuscular transmission].

BACKGROUND: Fade of the muscle contraction evoked by indirect tetanic nerve stimulation shows residual neuromuscular block. Anticholinesterases can reverse the partial block; however, they may also inhibit normal neuromuscular transmission and can cause fading responses by misuse of these drugs. The aim of this study is to investigate how neostigmine acts on normal neuromuscular function. METHODS: In cats, we observed a series of 8 consecutive muscular compound action potentials (mCAPs; M1-8) of the gastrocnemius muscle evoked by repetitive sciatic nerve stimulation at 100 Hz and calculated the M8/M1 amplitude ratio as an index of fading phenomenon. Neostigmine 0.05 mg x kg(-1) repetitively every 5 minutes before neuromuscular blocking agent had been administered, or after the complete recovery from vecuronium-induced block had been obtained. RESULTS: Neostigmine caused dose-dependent fade in the mCAPs. The mean doses (SD) of neostigmine for depressing M8/M1 ratio to 50% of baseline were 0.087 (0.029) mg x kg(-1) before use of neuromuscular blocking agent and 0.161 (0.070) mg x kg(-1) after the recovery from neuromuscular block. The fading responses induced by neostigmine were paradoxically reversed by small doses of vecuronium. CONCLUSIONS: Therapeutic doses of neostigmine administered during normal neuromuscular function cause fade of the repetitive muscle contractions. Neuromuscular monitoring should be used before the reversal with neostigmine.

[Pulmonary embolism induced by evacuator during transurethral resection of the prostate].

A 79-year-old man was scheduled to undergo transurethral resection of the hypertrophied prostate during general anesthesia. Anesthesia was maintained with sevoflurane 0.5-1.0% and nitrous oxide 50% in oxygen mixture. Immediately after using an evacuator to remove small resected pieces of the prostate, end-tidal carbon dioxide pressure (EtCO2) decreased suddenly from 31 mmHg to 18 mmHg. Concurrently, decreases in systolic blood pressure from 110 mmHg to 60 mmHg and oxygen saturation from 100% to 95%, and an increase in arterial-alveolar carbon dioxide tension difference (a-ADCO2) were observed. We initially suspected the onset of pulmonary thrombosis as the cause of these events, ventilated the patient's lungs with 100% oxygen and administered 5,000 units of heparine and vasopressors intravenously. However, transesophageal echocardiography done subsequently revealed the presence of strongly echogenic images compatible with the air in the left cardiac atrium and the contribution of the air to those events. The EtCO2, blood pressure, and oxygen saturation improved in about 20 minutes after the initial decrease of the EtCO2 had been detected. Thereafter, surgical procedure was done uneventfully. In routine anesthetic management of transurethral surgery, it should be considered that the sudden deterioration in vital signs may have been caused by evacuator used.

Comparative fading responses induced by mivacurium, cisatracurium, and d-tubocurarine in the evoked muscular compound action potentials of the cat.

PURPOSE: It has been suggested that the different degrees of fade induced by nondepolarizing neuromuscular blocking agents in repetitive muscular contractions may be due to the varying affinities or binding kinetics of presynaptic nicotinic receptors. We compared the degree of fade induced by mivacurium, cisatracurium, and d-tubocurarine in the cat muscular compound action potential (mCAP). METHODS: In 21 cats, mCAPs of the gastrocnemius muscle were evoked by paired (conditioning and test stimuli) and 2 Hz train-of-four (TOF) sciatic nerve stimulation. The interval between the paired stimuli was changed stepwise from 7 to 1000 ms. The ratios of the amplitude evoked by test stimulus to that evoked by the conditioning stimulus (M2/M1 ratios) and TOF ratios were measured. After baseline variables had been obtained, the cat received either mivacurium (0.08 mg x kg(-1), n = 7), cisatracurium (0.05 mg x kg(-1), n = 7), or d-tubocurarine (0.5 mg x kg(-1), n = 7). A series of M2/M1 ratios and TOF ratios were measured at various levels of partial block during recovery. RESULTS: At 10% of baseline amplitude, all agents significantly depressed the M2/M1 ratios (i.e., fade) at relatively longer intervals of paired stimuli (mivacurium, > or = 100 ms; cisatracurium. > or = 40 ms; and d-tubocurarine, > or = 20 ms), when compared with baseline. The order of activity to produce fade was mivacurium < cisatracurium < d-tubocurarine. A similar result was obtained in TOF ratios measured at various levels of neuromuscular block. CONCLUSION: Our results suggest that mivacurium shows a lesser degree of fade during partial neuromuscular block than cisatracurium and d-tubocurarine.

[A retrospective study in spinal anesthesia for sumo-wrestlers].

BACKGROUND: Spinal anesthesia for the Sumo-wrestler is thought to be difficult because of following reasons. 1. Sumo-wrestlers are so fatty and weighty that piercing spinal needle into the subarachnoid space is technically difficult. 2. The relationship between volume of local anesthetics and attained spinal anesthesia level is difficult to detect. 3. Upper airway can be easily obstructed during sedation. METHODS: Retrospectively, we compared 30 Sumo-wrestler patients (group S) with normal body weight patients (group N) concerning 17 items. RESULTS: While all patients in group N were approached from L 3 and L 4 interspinal space using 25 gauge spinal needles, 13 patients in group S were approached from another interspinal space, for example L 2 and L 3 or L 4 and L 5 and 40% of patients in group S needed 23 gauge spinal needles. The time intervals from the entrance into the operating room till the end of intrathecal administration of local anesthetics in group S and group N were 34 and 24 minutes, respectively (P < 0.05). The distances from the surface of the skin to subarachnoid space in group S and group N were 80 mm and 49 mm, respectively (P < 0.05). CONCLUSIONS: These results indicate that subarachnoid puncture in Sumo-wrestler patients is difficult and we should understand the specificities of spinal anesthesia for these patients.