Pharmacologic principles of cardiovascular drug administration to the critically ill.

The critically ill patient presents a pharmaceutical dilemma, with the clinical condition often necessitating the administration of potent medications. The underlying disease process often includes or produces multi-system failure, which will subsequently alter the response to drugs, with the potential to further compromise the acutely ill patient. In summary, the interplay of patient and drug provides a challenge to the medical staff in the provision of effective pharmacotherapy. Several steps can be followed to facilitate the achievement of optimal drug therapy at minimal toxicity. These include the following. 1. Drug Choice. The agent to be administered must be assessed by the practitioner with respect to efficacy in the particular disease state. 2. Patient Variables. Patients must also be evaluated for the presence of factors such as cardiovascular compromise, renal or hepatic dysfunction, pulmonary disease, gastrointestinal integrity, and hypoalbuminemia, all of which are known to alter drug kinetics or dynamics. Concurrent drug therapy must be reviewed to identify those drugs with the potential to interact with the agent to be administered. 3. Dose of the Selected Agent. The dose of the drug must be altered commensurate with those diseases observed. In the presence of multiple organ involvement, further alterations in dosage may be required. 4. Route of Administration. The drug in the selected dose must be given by a route that will result in reliable blood concentrations. Intravenous therapy is usually the route of choice. 5. Monitoring of Therapy. Therapeutic endpoints of the individual agents must be clearly defined and will include variables such as control of arrhythmias, determination of systolic and diastolic blood pressure, heart rate, and so forth. Dose-related toxicity serves as a warning sign of excessive drug doses. Patients must be monitored carefully to insure early detection of adverse effects and subsequent dose reduction by the practitioner. The monitoring of serum concentrations of drugs that possess a well defined therapeutic or toxic range is useful, if the limitations of this practice are remembered. Determinations of plasma concentration must be readily and routinely available to the practitioner to be useful in guiding dosage alterations, especially in emergency situations. The availability of this laboratory service is often a limiting factor. Additionally, standard methods of quantifying serum levels of drugs measure both free and bound drug together, providing one value. Changes in the pharmacologically active free fraction may therefore be undetected.(ABSTRACT TRUNCATED AT 400 WORDS)