Effects Of Three Intravenous Anesthetics On BP, ET And NO Responses To Induction Of General Anesthesia And Tracheal Intubation

Objective: We observed the changes of BP and HR during induction of general anesthesia with thiopental ,propofol and etomidate and tracheal intubation and searched the relationships between BP and ET , NO in order to provide bases theoretically for maintaining cardiovascular stability in clinical anaesthesia.Methods: Forty patients , ASA Ⅰ or Ⅱ, aged 35 to 55 years, weighting 56 to 68 kg, scheduled for elective surgery requiring tracheal intubation general anesthesia, without severe heart, brain, liver, kidney disorder and endocrine disease, were randomly divided into three groups: group T(n=13), group P(n=14) and group E(n=13). The patients were premedicated with midazolam 0.07 mg·kg^-1 and and atropine 0.5mg within 30min before surgery. On arriving in the operating room, the patients was punctured and indwelled canula in the right radial artery in order to monitor invasive blood pressure. After the patients were preoxygenated for 5min using a close-fitting face mask, the induction of general anesthesia was performed with fentanyl 3μg·kg^-1, thiopental 5mg·kg^-1 (or propofol 2 mg·kg^-1 or etomidate 0.3mg·kg^-1) and vecuronium 0.1 mg·kg^-1. 2min later, tracheal intubation was performed within 30 seconds, andthen mechanical ventilation was started with Drager Julian anesthetic machine. The enflurane was inhalated at 5min after intubation. The liquid 10ml ? kg"1 h"1 were infused. SBP, DBP, MAP and HR were continuously monitored. Blood samples were taken from peripheral vein at To (before induction), Tj (after induction before intubation), T2 (lmin after intubation), T3 (3min after intubation) and T4 (5min after intubation) for determination of plasma ET and NO concentrations. ET was detected by using radioimmunoassy (gamma counter), and NO was detected by using nitrate reductase(722 spectrophotometer). All the numerical data were expressed as mean ± standard deviation and students t test was used to establish significance. ANOVA was used for analysis of categorical data, linear correlation analysis was used to measure the coefficient of correlation between MAP and ET, NO in each group. All statistical analyses were performed using SPSS 10.0 software pack. Ap<0.05 was considered statistically significant. ApO.Ol was considered statistically significant extremely.ResultsNo significant differences could be seen in sex, age, weight among three groups(Table 1).Tj compared with To, the BP in three groups decreased significantly(p<0.01). The largest decrease in MAPwas in group P,and the secondary was in group T, but the lowest was in group E. The HR increased in group T, but decreased in group E(p<0.01).The small decrease in HR that occurred in group Pwas not significant (p>0.05) (Table 2). T2 compared with Tl9 the BP and HR in three groups increased significantly (p<0.01 or p<0.05). But T2 compared with To: the BP and HR increased in group T(p<0.01) ; the BP decreased(p<0.05) ,and HR was no significant differences in group P; the BP increased , and HR was no significant differences in group E. BP and HR returned gradually to baseline values after T2. MAP in group P was lower than that of group T and E at T3 and T4, and HR in group T was higher than that of group E at Ti and T2(p<0.01 or p<0.05) (Table 2).Ti compared to To, there were no changes in ET and ET/NO (p>0.05), but NO increased (p<0.01) in group T. There were that ET values decreased, NO values increased, and ET/NO values decreased in group P(p<0.01). The ET and ET/NO values decreased (p<0.01), and NO values were no changes statistically in group E. T2 compared to Ti, ET and ET/NO increased, but NO decreased significantly in three groups. T2 compared to To, the increasement of ET and ET/NO ,and the decreasement of No were seen only in group T. There were significant statistical differences in ET, NO and ET/NO values in group T at Ti to T4. There were also significant differences in ET, NO and ET/NO values between group T and P at t2; but there were significant differences in NO and ET/NO values between group P and E(Table 3).The relationships of MAP to ET and NO group T There was no correlation (r=0.016, p>0.05) between...