Keiichi Nitahara

Restoration of Train-of-Four Ratio with Neostigmine After Insufficient Recovery with Sugammadex in a Patient with Myasthenia Gravis.

We present a patient with myasthenia gravis in whom sugammadex failed to restore the train-of-four ratio (TOFR) sufficiently. When the patients TOFR count had recovered to 2, we administered 2 mg/kg of sugammadex. However, the TOFR did not recover to the preoperative value. An additional 2 mg/kg of sugammadex also had no effect. We then administered 30 μg/kg of neostigmine which restored the TOFR to more than the preoperative value. We speculate that exacerbation of myasthenia symptoms during surgery interfered with recovery of TOFR after sugammadex administration.

Recovery of train-of-four ratio to 0.70 and 0.90 is delayed in type 2 diabetes with vecuronium-induced neuromuscular block.

Context The recovery profile of train-of-four ratio to more than 0.70 in patients with diabetes mellitus has not been well investigated. Objective Our primary objective was to evaluate the spontaneous recovery profile of neuromuscular block by vecuronium until train-of-four ratio more than 0.90 in patients with type 2 diabetes mellitus compared with controls, using first dorsal interosseous electromyography. Design Single-centre prospective case–control study. Setting The operating theatres of Fukuoka University Hospital. Patients Fourteen adults with type 2 diabetes mellitus (diabetes mellitus group) and 14 control patients (control group) were included in this study. Intervention Evoked responses to train-of-four stimuli were measured by electromyography at the first dorsal interosseous muscle. General anaesthesia was induced with propofol, fentanyl and remifentanil. Vecuronium (0.1 mg kg−1) was administered to all patients. Anaesthesia was maintained with propofol, fentanyl and remifentanil. The neuromuscular block was assessed until spontaneous recovery to train-of-four ratio more than 0.90. Main outcome measures Recovery times to train-of-four ratio 0.70 and 0.90. Results Recovery times to train-of-four ratio 0.70 and 0.90 were significantly longer in the diabetes mellitus group than the control group (P = 0.041 and P = 0.027, respectively). The time from train-of-four ratio 0.25 to 0.90 was also significantly longer in the diabetes mellitus group than the control group (P = 0.029). In five of 14 patients in the diabetes mellitus group, the time from train-of-four ratio 0.25 to 0.90 was longer than 60 min, which is longer than the duration of action of neostigmine. The time from train-of-four ratio 0.25 to 0.90 was longer than 60 min in only one of 14 in the control group. Conclusion Recovery times to train-of-four ratio 0.70 and 0.90 were delayed in patients with type 2 diabetes mellitus. Neuromuscular block by vecuronium should be carefully monitored in patients with type 2 diabetes mellitus until recovery of train-of-four ratio to a safe level is confirmed.

Depression of evoked electromyographic (EEMG) responses by propofol in a patient with human T-cell lymphotropic virus type I-associated myelopathy (HAM)

IMPLICATIONS We report a patient with human T-cell lymphotropic virus type I-associated myelopathy. Although muscle strength in both of the upper extremities was normal in this patient, evoked electromyogram of the adductor pollicis was depressed by propofol at the induction of anesthesia.

Spontaneous Recovery of Paraplegia Caused by Spinal Epidural Hematoma after Removal of Epidural Catheter

We report a patient who developed paraplegia caused by a spinal epidural hematoma after removal of an epidural catheter, which resolved spontaneously. A 60-year-old woman underwent thoracoscopic partial resection of the left lung under general anesthesia combined with epidural anesthesia. She neither was coagulopathic nor had received anticoagulants. Paraplegia occurred 40 minutes after removal of the epidural catheter on the first postoperative day. Magnetic resonance images revealed a spinal epidural hematoma. Surgery was not required as the paraplegia gradually improved until, within 1 hour, it had completely resolved. Hypoesthesia had completely resolved by the third postoperative day.

Acceleromyography at the Flexor Hallucis Brevis Muscle Underestimates Residual Neuromuscular Blockade

Purpose: Recovery of the train-of-four ratio (TOFR) to > 0.9 in the upper limb is commonly used to determine that neuromuscular function has returned to the preoperative level. It is not known whether recovery of neuromuscular function can be determined in the same way using lower limb acceleromyography. We compared measurements of recov- ery from neuromuscular blockade using upper limb electromyography and lower limb acceleromyography. Methods: Twenty-nine patients who were scheduled for elective surgery were enrolled in this study. Patients were ex- cluded if they had neuromuscular disease or contraindications to neuromuscular blockade. General anesthesia was induced and maintained with propofol and fentanyl. Patients were monitored using electromyography at the first dorsal interosse- ous muscle of the upper limb and acceleromyography at the flexor hallucis brevis muscle of the lower limb. Vecuronium 0.1 mg/kg was administered for neuromuscular blockade, and the profile of the blockade was recorded, including onset time and recovery times to TOFR 0.7 and 0.9. Results were compared between the upper and lower limbs. Results: The first dorsal interosseous muscle of the upper limb was slower to recover to TOFR 0.7 and 0.9 than the flexor hallucis brevis muscle. When the TOFR at the flexor hallucis brevis muscle had recovered to 0.9, the TOFR at the first dorsal interosseous muscle was 0.44 ± 0.23. Conclusion: Monitoring the flexor hallucis brevis muscle using acceleromyography underestimates the residual neuro- muscular blockade.

Medial Approach to the Sciatic Nerve at the Popliteal Fossa in the Supine Position with Ultrasound Guidance and Nerve Stimulator

Ultrasound guided sciatic nerve block (SNB) at the popliteal fossa is performed with the lateral approach in the supine position or with the lateral or posterior approach in the prone position. When the sciatic nerve (SN) is blocked with the lateral approach in the supine position, the lower limb must be sufficiently elevated to enable adequate space around the knee joint for transducer application. When the SN is blocked in the prone position, the patients’ position needs to be changed. We report a medial approach to the SNB at the popliteal fossa in the supine position with ultrasound guidance. Ten patients scheduled for elective knee or foot surgery participated in this study. Patients were placed in the supine position, with the hip and knee on the operated side flexed and the thigh externally rotated at approximately 45 degrees. A block needle was inserted in-plane with the transducer toward the SN bifurcation from the medial side of the thigh. The block performance time for SNB was 1.8±0.5 min (1.3–3.1 min). All blocks were effective. Our medial approach to the SN in the supine position with ultrasound guidance does not require elevation of the patient’s lower limb or a change in the patient’s position.

Comparison of the Neuromuscular Profile of the First Dorsal Interosseous Muscle and the Flexor Hallucis Brevis Muscle as Measured by Electromyography

Lower limb muscles recover faster than upper limb muscles following administration of nondepolarizing neuromuscular relaxants until the train-of-four ratio (TOFR) reached 0.7. However, no study has been conducted to evaluate the recovery time of the flexor hallucis brevis muscle (FHBM), up to a TOFR of 0.9, which indicates satisfactory recovery of neuromuscular blockade. The aim of this study was to determine electromyographically the relationship between the TOFRs of the FHBM and the first dorsal interosseous muscle (FDIM), following 0.1 mg/kg of vecuronium. Eighteen patients were enrolled in this study. Electromyography of the FDIM and the FHBM was monitored. Onset times and recovery times to TOFRs of 0.7 and 0.9 of both muscles after administration of vecuronium were measured. The onset time in the FDIM was not different from that in the FHBM (𝑃 = 0.10). Recovery time to TOFR 0.7 was significantly faster in the FHBM than in the FDIM (𝑃 < 0.013). There was no significant difference in the meantime to reach TOFR 0.9 between the FDIM and the FHBM (𝑃 = 0.11). There is no clinical importance in the difference of neuromuscular recovery between the FHBM and the FDIM after TOFR reached 0.9 following administration of vecuronium.

The effect of adenosine triphosphate on vecuronium-induced neuromuscular block

Continuous IV adenosine triphosphate administration has been used during surgery in the expectation of analgesic and vasodilative effects. Because adenosine triphosphate inhibits neuromuscular transmission, we investigated whether the neuromuscular effect of vecuronium was enhanced by IV adenosine triphosphate in 29 patients randomly given either continuous IV adenosine triphosphate 0.1 mg · kg−1 · min−1 or 0.9% NaCl when undergoing elective minor surgery. Anesthesia was induced and maintained with propofol. Neuromuscular monitoring was recorded from the adductor pollicis muscle using electromyography with train-of-four stimulation of the ulnar nerve. Vecuronium 25, 30, or 40 &mgr;g/kg was given and lag time, onset time, and maximum block were recorded. ED50 and ED95 values for each group were derived from least squares linear regression analysis. ED50 and ED95 values were 29 &mgr;g/kg and 44 &mgr;g/kg, respectively, for the adenosine triphosphate group and 26 &mgr;g/kg and 46 &mgr;g/kg, respectively, for the controls. Differences in lag time, onset time, and neuromuscular responses between the two groups were not statistically significant. A significantly larger number of patients in the adenosine triphosphate group showed hypotension (systolic blood pressure <80 mm Hg). Our results demonstrated that adenosine triphosphate 0.1 mg · kg−1 · min−1 did not enhance the neuromuscular block induced by vecuronium.