Interaction between Mivacurium and Nitroglycerin / 대한마취과학회지

BACKGROUND: The neuromuscular blocking effects of a nondepolarizing neuromuscular blocker (NDNM) during a nitroglycerin (NTG) infusion were significantly potentiated and prolonged. NTG reduced the requirement of a NDNM in surgical patients. We investigated the influence of a NTG single bolus injection on a mivacurium nuromuscular blockade. METHODS: We studied 36 adult surgical patients, ASA physical status I or II, between 15 and 53 years old. Neuromuscular monitoring was measured by TOF-GUARD (Biometer Co., Denmark). Anesthesia was induced by thiopental sodium 3-5 mg/kg and fentanyl 3 microgram/kg, and maintained with 3 L/min N2O, 2 L/min O2 and 1 vol.% isoflurane. Patients were randomly assigned to 3 groups: 1) Control group (mivacurium 0.16 mg/kg), 2) N100 group (mivacurium 0.16 mg/kg, NTG 100 microgram), 3) N200 group (mivacurium 0.16 mg/kg, NTG 200 microgram). We measured the train-of-four (TOF) response from the beginning of recovery to the complete regaining of muscle twitch. RESULTS: NTG produced a prolongation of the neuromuscular blocking effect by mivacurium. T1 (contro group: 12.1 +/- 0.5, N100 group: 15.8 +/- 0.4 and N200 group: 11.6 +/- 0.4 min), T25 (16.4 +/- 0.4, 20.5 +/- 0.5 and 14.9 +/- 1.0 min), T75 (22.5 +/- 0.9, 29.4 +/- 0.7 and 20.1 +/- 1.0 min), T95 (27.3 +/- 0.6, 39.6 +/- 0.7 and 24.6 +/- 1.5 min) and the recovery index (6.1 +/- 0.6, 9.0 +/- 0.4 and 5.3 +/- 0.7 min) were significantly prolonged in the N100 and N200 groups (P < 0.05). CONCLUSION: These results suggest that a NTG bolus injection prolonged the neuromuscular blocking effect of mivacurium, dose relatively.

The Study of Priming with Vecuronium and Atracurium on Young and Elderly Patients / 대한마취과학회지

BACKGROUND: Succinylcholine is the muscle relaxant of choice for rapid endotracheal intubation, but may produce many side effects such as hyperkalemia, myalgia, increase intraocular pressure. Nondepolarizing muscle relaxants were used instead of succinylcholine, still late onset time was be dangerous. For this reason, priming principle was reported and applied to rapid intubation using nondepolarizing muscle relaxation. We studied the effect of priming with vecuronium and atracurium on elderly and young patients. METHODS: We were randomly assigned 40 patients and observed the effects of priming doses of vecuronium (0.01 mg/kg) and atracurium (0.05 mg/kg). Ten young (20-35 yrs) and ten elderly (65-75 yrs) patients were each placed in vecuronium and atracurium group. Arterial blood gas analysis and train of four (TOF) were determined before priming. All tests were performed again 4 min after vecuronium and 3 min after atracurium. We asked for symptoms and signs of muscle weakness. RESULTS: In arterial blood gas analysis and TOF ratio were decreased in both groups. There is no significant difference between two groups in all tests. PaO2 and TOF ratio were reduced more in elderly patients, significantly (P<0.05). Symptoms and signs of muscle weakness such as ptosis, dizziness, diplopia, swallowing difficulty and respiratory difficulty in elderly patients were more frequent than in young patients. CONCLUSIONS: Priming doses of vecuronium and atracurium produced greater decrease in muscle strength, PaO2 and TOF ratio in the elderly than in their younger counterparts. So using priming method in elderly patients, we need adequate pre-oxygenation and thorough monitoring before endotracheal intubation.

Neuromuscular Blocking Effect of Vecuronium in Electric Burned Patients for Endotracheal Intubation / 대한마취과학회지

BACKGROUND: In inducing anesthesia for burn patients, nondepolarizing muscle relaxant (NDMR) is usually used, because succinylcholine, a widely used muscle relaxant may cause hyperkalemia. It is well known that because burn patients show resistance to NDMR, a high dose of NDMR is needed for them. In this study, we wanted to know whether there is significant difference of the relaxation effect between 0.1 mg/Kg and 0.15 mg/Kg dose's of vecuronium, and between burn and unburn patients. METHODS: Subjects are 40 male patients having 1 or 2 ASA physical status (20 are burn patients and the other 20 are unburn patients). We divided them into 4 groups; 1) Group BI (burn patients, vecuronium 0.1 mg/Kg) 2) Group BII (burn Pts, vecuronium 0.15 mg/Kg) 3) Group UBI (unburn Pts, vecuronium 0.1 mg/Kg) 4) Group UBII (unburn Pts, vecuronium 0.15 mg/Kg). Average onset times (time from injection of vecuronium to zero first twitch height (T1)) were measured and intubating condition were scored on 0 to 4 scale. RESULTS: The onset time of vecuronium and distribution of intubation scores didn't show statistical differences among 4 groups. CONCLUSION: The onset time of vecuronium and intubating condition in burn patients dosen't show a difference from unburn patient.

Train-of-Four Fade Related to Potency during Recovery from Neuromuscular Block in Isolated Forearm / 대한마취과학회지

BACKGREOUND: The speed of action of nondepolarizing muscle relaxants might be correlated with the drug potency and the receptor-plasma concentration gradient. However, because of dissociation constants (KDs) being masked by plasma concentration following systemic administration, we investigated the degrees C of train-of-four (TOF) fade at various stages of the measured first twitch height of TOF (T1) during recovery related to potency of various muscle relaxants using isolated forearm technique. METHODS: Thirty two volunteers of the conscious healthy adults who were not receiving any medication which might have influence neuromuscular transmission were involved in this study. The electrodes were applied over the ulnar nerve at the wrist and supramaximal transcutaneous single twitch stimulation (0.1 Hz) delivered by a peripheral nerve stimulator (Innervator, Fisher & Paykel, New Zealand) using a 0.2 ms square wave pulses was applied. The twitch response of the thumb adductor was measured mechanomyographically using a 2 kg Load Cell strain gauge (Model No. 505H, RS Components Ltd., UK) with a thumb piece modification. Following a 5 min. period of stabilization, forearm pneumatic tourniquet was inflated to 300 mmHg in order to occlude the systemic circulation. The equipotent dose (ED95 0.1) of various muscle relaxants diluted in 20 ml of saline was injected into a vein on the dorsal hand respectively: rocuronium 30 microgram/kg, atracurium 25 microgram/kg, mivacurium 8 microgram/kg and vecuronium 4 microgram/kg. Eight volunteers received each dose. The forearm tourniquet was released at 3 min after drugs given. The neuromuscular block was allowed to recovery spontaneously, and at 25, 50, 75 and 100% recovery of control twitch height, TOF stimulation (2 Hz for 2 s) was administered in order to compare TOF ratios between musle relaxants. RESULTS: In the aminosteroid compounds, the TOF ratios of rocuronium were greater than those of vecuronium at all of the assessment points during recovery. In the benzylisoquinolium compounds, the TOF ratios of atracurium were greater than those of mivacurium at 25 and 50% recovery of control twitch height. CONCLUSION: The degree of TOF fade during recovery is related to drug potency at presynaptic receptors separated from the effects of plasma drug concentration.