Radiation-induced adaptive response of nucleoplasmic bridges in human peripheral blood lymphocytes / 中华放射医学与防护杂志

Objective To explore whether a low dose of 60Co γ-rays could induce the adaptive response in the formation of nucleoplasmic bridges (NPB) in human peripheral blood lymphocytes,and if so,the range of the priming dose.Methods Human peripheral blood samples from healthy males were collected and irradiated with 0,20,50,75,100,150 and 200 mGy (dose-rate was 25 mGy/min) of 60Co γ-rays.After 6 h,the samples were irradiated with a challenge dose of 2 Gy (dose-rate was 1 Gy/min).The cytokinesis-block micronucleus (CBMN) assay was carried out to analyze the NPB and micronuclei (MN) formation in binucleated cells.Results Within the dose range of 0-200 mGy,the yields of NPB and MN increased with irradiation dose of γ-rays and the dose response of NPB followed with a linearquadratic equation of y =(1.5 × 10-4) x2-(5.67 × 10-3)x + 0.598 (R2 =0.893 8).Compared with the samples irradiated with 2 Gy alone,the yields of NPB and MN were significantly reduced when the samples were irradiated with a priming dose of 75-100 mGy before 2 Gy irradiation (U =2.66,2.97,3.96,5.89,P ＜0.05).The biggest decrease ratio of NPB yields approached to 43.2％ at the priming dose of 100 mGy.Conclusions Low doses in the range of 75-100 mGy of 60Co γ-rays could induce the adaptive response of NPB formation in human peripheral blood lymphocytes.

Priming technique can alleviate the withdrawal responses associated with intravenous administration of rocuronium / 대한마취과학회지

BACKGROUND: Intravenous injection of rocuronium is associated with withdrawal responses which are attributable to the pain from the injection of rocuronium. Several methods have been proposed to abolish and attenuate rocuronium-induced pain. We hypothesized priming dose of rocuronium could reduce withdrawal responses associated with administering a second large dose of rocuronium for tracheal intubation. We compared the efficacy of the priming dose technique of rocuronium with intravenous lidocaine as a pre-treatment for the prevention of withdrawal responses associated with rocuronium injection. METHODS: We recruited 150 patients aged between 18 and 60 years, ASA physical status 1 or 2, who were going to undergo elective surgery requiring general anesthesia. Patients were allocated into three groups. Group C received normal saline, Group L received lidocaine 1 mg/kg, and Group P received rocuronium 0.06 mg/kg 2 minutes before administering a second large dose of rocuronium for tracheal intubation. After the loss of consciousness, rocuronium 0.6 mg/kg was administered intravenously over 10 seconds for tracheal intubation. The withdrawal responses to the injection of rocuronium were evaluated. RESULTS: The incidence of withdrawal responses associated with rocuronium injection for tracheal intubation was 56, 50, 24% in group C, group L, and group P, respectively. The incidence of withdrawal responses was lower in group P than group C and group L, but there was no difference between group L and group C. CONCLUSIONS: Priming dose technique is a useful clinical method to alleviate withdrawal responses associated with rocuronium injection.

The Effect of a Priming Dose of Atracurium on the Onset Time in Rapid Sequence Tracheal Intubation / 대한마취과학회지

BACKGROUND: Depolarizing muscle relaxant, frequently used for rapid sequence endotracheal intubation in clinical field, has serious complication that occur intermittently, such as, hyperkalemia, increased intraoccular pressure and sudden cardiac arrest, especially in infants and adolescents. So the priming principle, i.e., the administration of a subparalyzing dose of a nondepolarizing muscle relaxant (priming dose) prior to the intubating dose, was developed for rapid sequence endotracheal intubation with nondepolarizing muscle relaxant. However, the priming dose sometimes causes complications, such as, swallowing difficulty or pulmonary aspiration, and this can cause patient discomfort or fatal complications. In this study we examined proper atracurium priming dose and evaluated possible complications of priming doses. METHODS: One hundred patients, scheduled for elective surgery were randomly allocated into five groups according to the priming dose used (group 1; 0, group 2; 0.03, group 3; 0.06, group 4; 0.09, group 5; 0.12 mg/kg). Patients received a midazolam and fentanyl injection, the base line TOF ratio was measured, and an intubating dose was given. We also examined changes in vital sign for 20 minutes after injection and noted the time when the twitch height became zero (onset time). RESULTS: In group 1, the onset time was 107 +/- 22.9 sec, and in groups 4 and 5, the onset times were 85.0 +/- 15.6 and 69.9 +/- 19.3 sec, respectively. But, in group 5, some patients showed tachycardia and swallowing difficulty. CONCLUSIONS: The optimal priming dose of atracurium was determined as 0.09 mg/kg, in most cases, however patients sensitivity to the atracurium should be considered.

The Effect of Small Dose of Nondepolarizing Muscle Relaxant Administered Prior to Succinylcholine on Intubating Condition / 대한마취과학회지

Subparalyzing dose of nodepolarizing relaxants prior to injection of succinylcholine has been used to prevent various adverse effects induced after succinylcholine. For investigating interactions between succinylcholine and small doses of four non-depolar-izing agents, the 112 subjects that were ASA class 1-2 and no existing neuromuscular conduction system disorder were divided into 5 groups that were control group(only succinylcholine 1 mg/kg) and pretreated group d-tubocurarine 0.5 mg/kg, atracurium 0.08 mg/kg, vecuronium 0.01 mg/kg and pancuronium 0.01 mg/kg. In each group, the plasma concentration of K+ and PChE before and after use of succinylcholine, fasciculation, onset and recovery time of succinylcholine block and intubating conditon were observed. The results are as follows; In the pretreated group, there were no significant changes of plasma concentration of K+ and plasma cholinesterase(Table 3) but diminished the incidence of fascieulation, delayed the onset time and shorted the recovery time of succinylcholine block(Table 4), and worse in intubating condition(Table 5) except pancuronium treated group. It was concluded that these seem to make worse condition of intubation, while small doses of nondepolarizing muscle relaxants except pancuronium antagonize depolarizing muscle relaxant.

The Effect of Small Dose of Nondepolarizing Muscle Relaxant Administered Prior to Succinylcholine on Intubating Condition / 대한마취과학회지

Subparalyzing dose of nodepolarizing relaxants prior to injection of succinylcholine has been used to prevent various adverse effects induced after succinylcholine. For investigating interactions between succinylcholine and small doses of four non-depolar-izing agents, the 112 subjects that were ASA class 1-2 and no existing neuromuscular conduction system disorder were divided into 5 groups that were control group(only succinylcholine 1 mg/kg) and pretreated group d-tubocurarine 0.5 mg/kg, atracurium 0.08 mg/kg, vecuronium 0.01 mg/kg and pancuronium 0.01 mg/kg. In each group, the plasma concentration of K+ and PChE before and after use of succinylcholine, fasciculation, onset and recovery time of succinylcholine block and intubating conditon were observed. The results are as follows; In the pretreated group, there were no significant changes of plasma concentration of K+ and plasma cholinesterase(Table 3) but diminished the incidence of fascieulation, delayed the onset time and shorted the recovery time of succinylcholine block(Table 4), and worse in intubating condition(Table 5) except pancuronium treated group. It was concluded that these seem to make worse condition of intubation, while small doses of nondepolarizing muscle relaxants except pancuronium antagonize depolarizing muscle relaxant.

The Train - of - Four Response on the Priming Dose of Various Nondepolarizing Muscle Relaxants / 대한마취과학회지

The priming principle refers to the administration of a small subparalyzing dose (priming dose) of a nondepolarizing muscle relaxant, such dose not cause respiratory depression or any other clinical signs, a few minutes prior to the administration of the larger intubating dose. This study was designed to investigate the influence of a priming dose of vecuronium (0.008 mg/kg), pancuronium (0.008 mg/kg) and d-tubocurarine (0.04 nig/kg) on the relationship between the depres- sion in the first twitch (T2%) of the train-of-four (TOF) and TOF ratio (T4R,%) in 27 ASA class I or II patients. After induction with thiopental sodium 5-6mg/kg, neuromuscular monitoring was carried out by stimulation of ulnar nerve at a frequency of 2 Hz every 20 seconds using a ABM (Datex) to measure the compound evoked electromyographic response of hypothenar muscle. Following calibration of control twitch height, tracheal intubation was performed after succinyl-choline 1 mg/kg IV. Anesthesia was maintained with oxygen, NO (50%) and enflurane (1-2%) in all patients. When the TOF response recovered to 100% of the control, the priming dose was administer-ed. The patients were randomly divided into three groups according to nondepolarizing muscle relax-ant used; vecuronium (n=9), pancuronium (n=8) and tubocurarine (n=10) group respectively. T1 and T4R were measured for 25 minutes after administration of priming dose in each group. The results were as follow: 1) There was no change in T, after priming in all groups. 2) T4R began to decrease significantly at 2 minutes after priming and still decreased significantly at 25 minutes compared to before priming. 3) The time for maximal decrease in T4R (%) proceded by the priming dose was 7 minutes in all groups; 60.7+/-8.6% in vecuronium group, 74.8+/-12.3% in pancuronium group and 78.3+/-11.3% in tubocurarine group.