Dobutamine

Mechanism of Action

Dobutamine is used as a pharmacological agent and has both ionotropic and chronotropic effects depending on the dose. Because of its inotropic effects on the myocardium through binding and activating the beta-1 receptors selectively.[7] The medication is indicated clinically for decompensated congestive heart failure because of the sympathomimetic effects. Dobutamine's ionotropic effect increases contractility, leading to decreased end-systolic volume and, therefore, increased stroke volume. The increase in stroke volume leads to an augmentation of the cardiac output of the heart.[8] The changes in cardiac output allow for the baroreceptor-mediated response to decrease the systemic vascular resistance and cause little to no change in the arterial blood pressure. In addition to the well-known beta-1 activity, dobutamine has been shown to have some beta-2 activity, which contributes to the reduction in the systemic vascular resistance, and alpha-1 activity, to an even lesser extent, whose vasoconstrictive effects are negated by the baroreceptor mediated response and beta-2 activity.

Administration

Dobutamine administration is via large intravenous access and infusion pump for inotropic support in decompensated congestive heart failure, stress echocardiogram, and stress nuclear testing. The dosage for cardiac decompensation in heart failure can begin with one-half to one mcg/kg/min and increase up to a maximum of 40 mcg/kg/min. The lower doses of dobutamine can be prescribed at 2.5 to 5.0 mcg/kg/min, and the higher end of dobutamine doses can be 5.0 to 20.0 mcg/kg/min.[9] The dose for the stress echocardiogram and stress nuclear test is initiated at five mcg/kg/min and can be increased in intervals of 10 mcg/kg/min every 3 to 5 minutes until reaching the target heart rate. Dobutamine comes in a solution as a racemic mixture of both positive and negative enantiomers for intravenous administration. The positive enantiomer in the solution is predominately selective for the beta sympathetic receptors, mainly beta 1 and 2, whereas the negative enantiomer has been shown in studies to be selective for the alpha one receptors.[10]

Adverse Effects

Dobutamine administration can lead to possible adverse reactions, mainly due to sympathomimetic activity. The majority of patients taking this medication have experienced a rise in the systolic blood pressure of 10 to 20 mmHg and an increase of 5 to 10 beats per minute in their heart rate. There have been reports of further increases in systolic blood pressure and heart rate. In about 10% of the patients, there can be a rise of 30 beats per minute or more in the heart rate, and in about 7.5% of patients, there can be an increase of 50 mmHg or more in the systolic blood pressure. Patients with preexisting hypertension are more susceptible to the adverse effects on systolic blood pressure when using dobutamine.[11]

Dobutamine increases the risk of rapid ventricular response in patients with preexisting atrial fibrillation. The recommendation is that these patients use a regimen of digoxin before starting dobutamine to decrease the risk of developing atrial fibrillation with a rapid ventricular response. There has been an increased risk of developing premature ventricular beats during the administration of dobutamine. About 5% of patients experience premature ventricular beats.[12]

Other adverse effects caused by this medication include hypotension rarely. While increases in systolic blood pressure are common due to dobutamine, hypotension can occur less frequently due to the decreases in systemic vascular resistance. Recommendations include decreasing the dose or stopping the drug to reverse the hypotensive effects.

Phlebitis at the site of the intravenous administration can occur, but it an uncommon reaction. Dobutamine can rarely reduce the potassium concentrations to hypokalemic levels. Other rare adverse effects have occurred in one to three percent of the patients, including nausea, headaches, chest pain, palpitations, and shortness of breath. Dobutamine contains sulfite, which can lead to reactions in rare patients with sulfite hypersensitivity.

Contraindications

According to the Food and Drug Administration, Dobutamine use is contraindicated in patients with a noted history of allergic reactions to either previous dobutamine use or any sulfite use. The medication is contraindicated in patients with acute myocardial infarction, unstable angina, left main stem disease, severe hypertension, arrhythmias, acute myocarditis or pericarditis, hypokalemia and idiopathic hypertrophic sub-aortic stenosis.

Monitoring

Throughout the administration of this medication, there should be continuous monitoring using cardiac monitor and blood pressure checks because dobutamine is typically given to unstable patients and can lead to serious effects quickly that require monitoring and corrective action. The clinician can reduce the dose of dobutamine or stop the medication if the patient experiences adverse effects.

Toxicity

Dobutamine toxicity is rare, and the half-life is short at 2 minutes. Symptoms are generally due to sympathetic overstimulation and can include chest pain, palpitations, headaches, tremors, shortness of breath, nausea, and vomiting. To reverse the tachycardia caused by dobutamine, metoprolol intravenous can be given.

Enhancing Healthcare Team Outcomes

Dobutamine is a medication used in the ICU to manage low blood pressure. While the drug is safe, its use requires close monitoring as it has the potential to raise blood pressure and cause arrhythmia. Therefore the involvement of an interprofessional healthcare team is the optimal approach to ensuring therapeutic effectiveness and avoiding adverse effects. This team includes clinicians, specialists, mid-level practitioners, nurses, and pharmacists. Nurses perform IV dobutamine administration; hence these professionals should be familiar with the dosing and what parameters to monitor. Overall, the effects of dobutamine are short-lived. As soon as the infusion stops, the hemodynamic parameters will reverse. Collaboration and open communication between all interprofessional team members will drive the best patient results with dobutamine and any other drugs or procedures. [Level 5]