Effects Of Milrinone On Hemodynamics During Induction Of Anesthesia In Elderly Patients

Objective Because elderly patients physiological function gradually diminishes, cardiac function and cardiac reserve is increasingly reduced, vascular sclerosis, The cushioning mechanism is reducing efficiency, and therefore prone to hemodynamic unstable during induction of anesthesia. Mainly for hypotension after induction of anesthesia and hypertension after tracheal cannula. The hemodynamic unstable, especially hypotension after the induction of anesthesia, can lead to tissues hypoperfusion, increased anesthesia-related risks and mortality. Milrinone is a widely use phosphodiesterase-3 inhibitor, that increases cardiac and vascular cyclic adenosine monophosphate(c AMP) resulting in improved cardiac contractility and vasodilation. This study will use the non-invasive monitoring of cardiac output impedance cardiography(ICG), observed and confirmed, intravenous small doses milrinone before anesthesia whether helps to maintain induction of anesthesia in elderly patients with stable hemodynamics.Methods Sixty patients were enrolled in this study. All patients over 65 years of age, ASA Ⅰ~ Ⅱgrade, cardiac function Ⅰ~ Ⅱ grade, weighing 37 ~ 91 kg, height 150 ~ 178 cm.Patients were randomly divided into milrinone group(group M) and the control group(group C) by random number table. Before induction of anesthesia, patients in group M was received milrinone at a loading dose of 50μg/kg prior, then followed by 0.375μg/kg.min continuous infusion for 30 minutes, while group C injected with the same volume of saline. Both groups anesthesia was induced with etomidate 0.3mg/kg, sufentanil 0.4ug/kg, rocuronium 0.6mg/kg. Endotracheal intubation was performed 3min after the administration of rocuronium. An observer, unaware of the group allocation, made observation of SBP, DBP, MAP, HR, CO, CI, SVR and TFC before treatment(T0), after treatment(T1),before intubation(T2), and 1min(T3), 3min(T4), 5min(T5), 10min(T6) after intubation. And the fluid volume during induction, the amount of phenylephrine and ephedrine, the number of platelets before and after surgery, and adverse reactions such as headache and ventricular arrhythmias occurs also recorded.Results There were no significant differences in gender, age, weight, ASA classification and cardiac function(P> 0.05). Compared with group C, M group of patients each hemodynamic parameters were no significant difference at T0(P> 0.05). CO and CI were significantly increased at T1 ~ T6(P <0.05). MAP was significantly decreased at T1 and T3(P <0.05), the MAP at the rest time point were no statistically significant(P> 0.05). HR at T1 point was significantly increased(P <0.05), the HR at the rest time were no statistically significant(P> 0.05). The SVR at T1 ~ T6 were statistically lower(P <0.05). The TFC at each time point were no significantly difference(P> 0.05). Compared with at T0, M patients CO and CI at T1 and T3 were significantly increased(P <0.05), the rest of the point’s CO and CI were no significantly difference(P> 0.05). MAP at T3, T4 were not significantly difference(P> 0.05), remaining at each time point MAP decreased(P <0.05). HR at T1 significantly increased(P <0.05), HR at T2 was significantly decreased(P <0.05), the rest time point of the HR was no significantly difference(P> 0.05). T1 ~ T6 point SVR were significantly lower(P <0.05). TFC at any point was not statistically difference(P> 0.05). Group C patients at T1 various hemodynamic parameters showed no significant difference(P> 0.05). CO and CI at T2, T5, T6 were significantly lower(P <0.05), remaining at each time point was no significant difference(P> 0.05). MAP at T3 was significantly higher(P <0.05), MAP at T4 was no significant difference(P> 0.05), remaining at each time point MAPdecreased significantly(P <0.05). HR was significantly lower at T2(P <0.05), the rest of the HR point was no significant difference(P> 0.05). SVR at T4 was no significant difference(P> 0.05), remaining at each time point SVR was significantly lower(P <0.05). TFC at T1 ~ T6 were no significant difference(P> 0.05). Compared with group C, M group patients vasoactive drugs significantly reduced the amount. Platelet count was not significantly changed. Two groups of patients were no arrhythmias and headache.Conclusion Intravenous a small dose of milrinone before anesthesia may improve the patient’s cardiac output, reducing peripheral resistance,reduced cardiac output lower which caused by the induction of anesthesia., and helps to maintain induction of anesthesia in elderly patients with stable hemodynamics.