| Objective The children required ventilatory support in the intensive care unit often feel so anxious that they can't maintain the coordination between spontaneous breath and mechanic ventilation. The effect of ventilatory support will be decreased remarkably and the possibility of death maybe increased. At this time, it is very essential to use some sedative to minimize the children's anxious. The application of many kinds of sedative (for example barbital, morphine, propofol) has been confined because of their serious side-effect in critically ill patients, and the more important cause is that sedative's depression on central respiratory system maybe conflict with the modern proposition about mechanic ventilation. It is necessary to use some sedative with few side-effect and more effective, and this sedative must be adjusted at every stage so as to achieve controlled status of sedative. The objective of this experiment is to determine the effect of midazolam in patients with respirator and the influence on circulation and respiration, to evaluate the relationship between blood midazolam concentration and status of sedation. Metheds 1. The standard of patients admitted into the test.Eighteen patients, referred to the Tianjin Children' Hospital with receiving ventilation, were enrolled in this study. Ail cases before midazolam infusion fulfilled the following classifications: (1) Conscious and Ramsay score of more than 2 grade; (2) Not used the other sedatives at same time; (3) Without serious circulation, liver or renal disorders; (4)Respirator used of more than 48 hours duration.2. The method of using midazolamAfter mechanic ventilation had begun for 2 hours, the children were treated by continuous infusing . The starting load dose of midazolam was 0.1 to 0.15mg/kg, to be diluted in NS 5-10 ml, and then intravenously with 0.1 mg/kg/h (concentration less than 1mg/ml). If the patient appeared anxious again after 4 hours, the infusion rate of midazolam was adjusted to 0.2-0.25mg/kg/h to achieve an appropriate status of sedation to maintain Ramsay score 2-5 grades in real-time evaluating. The real-time measurements as follow:3. The clinical effect and measurement of plasma midazolam concentration as follow(1)To detect the arterial blood gas analysis at Oh,2h and 24h after the ventilation.(2)To observe the change of heart rate, breath, blood pressure(SBP/DBP) and Ramsay score per hour.(3)To measure the concentration of midazolam for each sample by high performance liquid chromatography(HPLC) until the continuous infusing time had been more than 24 hours. 4.High performance liquid chromatography (HPLC)An HPLC was used with Bondapak C18 (4.6mm *200mm, 10um) as chromatography column, methanol(PH:7.5)-phosphate buffer(65:35,v/v) as mobile phase, column temperature was 25 , photodiodes detection was at 240nm, the rate of mobile phase was 0.8ml/min. Results 1. Sedate effectAll cases got a excellent sedation level in 10~20min after midazolam administer, the effect of sedation could reach and keep 2-5 grades and obtained the clinical steady of more than 24 hours subsequently. The patients could steadily maintain the condition of sedation during continuous infusion midazolam.2. The influence on circulation and respirationBiood pressure was detected at Oh, 2h and 24h after the start of mechanic ventilation, and no significant differences between the time points (P>0.05). Heart rate had decreased and dosed to normal(P<0.01); Breath rate had decreased to 40/min approximately which reached the level of ventilation, consequently, conformed to in-phase between spontaneous breath and mechanic ventilation. It had significant differences between Oh and 2h(P<0.01). Heart rate and breath rate had no significant differences at 2h, 24h(P>0.05). S.The change of arterial blood gas analysisPaCO2 was detected to 5.92~3.91kPa after the infusion, this change had statistically significant difference (P<0.01); PaO2, SaO2 were significantly higher than those before midazolam infusion...
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