[The Distance between the Sciatic Nerve Bifurcation and Popliteal Fossa in Japanese].

BACKGROUND: The bifurcation into tibial nerve and common peroneal nerve is generally targeted for sciatic nerve block at popliteal approach. However, it is sometimes difficult to determine the exact bifurcation point in clinical situation. The mean distance between the popliteal fossa and division of sciatic nerve (DPDSN) was reported approximately 6 cm ± 2.5 cm in Caucasian cadaver study. We also studied DPDSN in Japanese cadaver to find ethnic difference. METHODS: We dissected and recorded DPDSN and distance from gluteal fold to heel (foot length : FL) in 15 cadavers. RESULTS: Mean DPDSN was 2.46 ± 2.00 cm (range: 0 to 8.8 cm). The DPDSN and FL were not correlated. CONCLUSIONS: DPDSN of Japanese cadaver is shorter than the previously reported data in Caucasian cadaver. Since the DPDSN has inter-individual and intra-individual differences, we should estimate the DPDSN carefully in each leg using ultrasonography and nerve stimulator.

Prediction of optimal reversal dose of sugammadex after rocuronium administration in adult surgical patients.

The objective of this study was to determine the point after sugammadex administration at which sufficient or insufficient dose could be determined, using first twitch height of train-of-four (T1 height) or train-of-four ratio (TOFR) as indicators. Groups A and B received 1 mg/kg and 0.5 mg/kg of sugammadex, respectively, as a first dose when the second twitch reappeared in train-of-four stimulation, and Groups C and D received 1 mg/kg and 0.5 mg/kg of sugammadex, respectively, as the first dose at posttetanic counts 1-3. Five minutes after the first dose, an additional 1 mg/kg of sugammadex was administered and changes in T1 height and TOFR were observed. Patients were divided into a recovered group and a partly recovered group, based on percentage changes in T1 height after additional dosing. T1 height and TOFR during the 5 min after first dose were then compared. In the recovered group, TOFR exceeded 90% in all patients at 3 min after sugammadex administration. In the partly recovered group, none of the patients had a TOFR above 90% at 3 min after sugammadex administration. An additional dose of sugammadex can be considered unnecessary if the train-of-four ratio is ≥90% at 3 min after sugammadex administration. This trial is registered with UMIN000007245.

A temporary decrease in twitch response following reversal of rocuronium-induced neuromuscular block with a small dose of sugammadex in a pediatric patient.

We report a temporary decrease in twitch response following reversal of rocuronium-induced neuromuscular block with a small dose of sugammadex in our dose-finding study in pediatric patients. A 19-month-old female infant (9.6 kg, 80 cm) was scheduled for elective cheiloplasty surgery. Anesthesia was induced with nitrous oxide 50% and sevoflurane 5% and maintained with air, oxygen, sevoflurane 3%, and fentanyl (total, 3 µg/kg). Neuromuscular monitoring was performed at the adductor pollicis muscle after induction of anesthesia but before the administration of rocuronium. Total dose of rocuronium during the surgery was 0.9 mg/kg. Neuromuscular block was reversed with 0.5 mg/kg sugammadex when one response was observed with post-tetanic count stimulation. Twitch responses after sugammadex administration showed a temporary decrease after its initial recovery. Maximum decreases in twitch responses were observed 17 min after initial dose of sugammadex. Twitch responses recovered to their control values after additional doses of 3.5 mg/kg sugammadex (4 mg/kg in total). Time from sugammadex administration to maximum decreases in twitch responses is earlier than has been reported in adults (20-70 min). It is demonstrated that following neuromuscular block reversal with insufficient dose of sugammadex, there is a possibility of the recurrence of residual paralysis within less than 20 min in pediatric patients.

Monitoring of neuromuscular blockade in one muscle group alone may not reflect recovery of total muscle function in patients with ocular myasthenia gravis.

PURPOSE: We report on two patients with ocular myasthenia gravis who received rocuronium, followed later by sugammadex to reverse neuromuscular blockade. Recovery was monitored simultaneously at the adductor pollicis muscle (APM) and the corrugator supercilii muscle (CSM). CLINICAL FEATURES: Two patients with ocular myasthenia gravis (case 1: 74 yr-old female, 54 kg; case 2: 71 yr-old male, 72 kg) were scheduled for surgery under general anesthesia. Neuromuscular blockade was induced with rocuronium 0.3 mg·kg(-1) after placing two separate monitors at the APM and the CSM, respectively. Additional doses of rocuronium 0.1-0.2 mg·kg(-1) were given to maintain neuromuscular blockade at fewer than two twitches at the APM during surgery. Train-of-four response at the CSM did not show recovery of the twitch after its initial disappearance. At the end of surgery, sugammadex was administered. Twitch height at the APM recovered to the control value in 12 min (case 1) and 13 min (case 2) after sugammadex administration; however, twitch height at the CSM took 26 min (case 1) and 14 min (case 2) to recover to the control value. CONCLUSION: After rocuronium-induced paralysis in both patients with ocular myasthenia, spontaneous recovery and sugammadex-assisted recovery were slower at the CSM than at the APM. In patients without the disorder, CSM recovery is faster than APM recovery. Thus, in ocular myasthenia gravis, neuromuscular recovery at the APM may not reflect recovery of all muscles.

[Evaluation of neuromuscular blockade using TOF-Watch SX in type 2 diabetes patients].

BACKGROUND: Differences in the supramaximal current (STIM) and sensitivity of the transducer (SENS) after calibration using mode "CAL2" of the neuromuscular accelermyography (TOF-Watch SX, MSD, Japan) between type 2 diabetic and non-diabetic patients were evaluated undergoing general anesthesia. METHODS: Thirty four elective surgical patients (20-69 years) were enrolled in this study. We evaluated STIM, SENS, onset time of rocuronium (onset time), time from onset to first T1 appearance (T1 appearance) and time from T1 appearance to T2 appearance (T1-T2 time) by using TOF stimulation between type 2 diabetic patients and non-diabetic patients, retrospectively. RESULTS: Thirteen diabetic patients (DM group) and twenty one non-diabetic patients (non-DM group) were included in this analysis. The values of SENS in DM group were significantly higher compared to non-DM patients (207 +/- 59 vs 113 +/- 44). However, STIM did not differ significantly between the two groups. Anesthesia in the 6 patients in DM group (SEV-DM group) and 14 patients in the non-DM group (SEV-non DM group) were maintained with sevoflurane. The other 14 patients were maintained with desflurane (DES-DM: n = 7 and DES-non DM: n = 7). A significant difference in the SENS values only was observed between the two SEV groups. On the other hand, the onset time, T1 appearance and T1-T2 time were significantly longer in DES-DM patients than those in the DES-non DM group. CONCLUSIONS: It is demonstrated that the values in the SENS and the recovery speed (T1-T2 time) under measuring the degree of neuromuscular blockade by TOF stimulation were significantly higher in diabetic patients compared to non-diabetic patients. The present study provides additional confirmation of low neuromuscular response under peripheral electrical stimulation using TOF-Watch SX in type 2 diabetes patients, and attention should be paid to the evaluation of neuromuscular block using TOF-Watch SX in diabetic patients.

[Characteristics and effectiveness of sugammadex].

Sugammadex was synthesized as a selective reversal agent for rocuronium, a steroidal non-depolarizing neuromuscular blocking (NMB) agent. Sugammadex exerts its effect by forming very tight water-soluble complexes at a 1 : 1 ratio with steroidal NMB agents. Because the reversal of NMB could not sufficiently be completed by anti-cholinesterase agents such as neostigmine, we often had to wait until their spontaneous recovery. Sugammadex altered the situation because of its rapid and potent antagonistic action. The rapid reversal can be explained by rapid redistribution of free rocuronium from the neuromuscular junction to the plasma. The reversal effects are not influenced by anesthetics. There is no interaction with cholinergic systems. Therefore, undesired side effects attendant with anti-cholinesterases are not seen. This article provides information on the characteristics and effectiveness of sugammadex.