HEMODYNAMIC DRUGS

This chapter contains a brief description of eight pharmaceutical agents given by continuous intravenous infusion to support the circulation. Each agent is listed below in order of presentation. Drugs marked by an asterisk have a dose chart included in the chapter.

1. Amrinone*

2. Dobutamine*

3. Dopamine*

4. Epinephrine

5. Labetalol

6. Nitroglycerin*

7. Nitroprusside*

8. Norepinephrine

INFUSION RATES

Because the drugs in this chapter are administered by continuous infusion, the recommended doses are expressed as dose rates, either in micrograms per minute (ug/min) or micrograms per kilogram body weight per minute (ug/kg/min). To deliver the recommended dose rate, the concentration of the drug in the infusate must be known. The infusion rate (i.e., the rate at which the infusate is delivered) is then determined as the ratio of the dose rate to the drug concentration in the infusate. In this case, the desired dose rate is R ug/min, and the drug concentration in the infusate is C ug/mL, so the ratio R/C derives the infusion rate in mL/min. The infusion rate can be converted to microdrops/minute by multiplying mL/min by 60 (because there are 60 microdrops per mL). The conversion to microdrops facilitates control of infusion rates when small volumes of fluid are infused. Therefore, all infusion rates included in the drug dosing charts in this chapter are expressed in microdrops/minute. The volumetric equivalent of microdrops/minute is mL/hr (i.e., microdrops/minute ´ 60/60 = mL/hr).