Dopamine

INTRODUCTION

Indications

Adjunct to standard measures to improve: Blood pressure, Cardiac output, Urine output in treatment of shock unresponsive to fluid replacement.

Action

Small doses (0.5–3 mcg/kg/min) stimulate dopaminergic receptors, producing renal vasodilation. Larger doses (2–10 mcg/kg/min) stimulate dopaminergic and beta₁-adrenergic receptors, producing cardiac stimulation and renal vasodilation. Doses >10 mcg/kg/min stimulate alpha-adrenergic receptors and may cause renal vasoconstriction. Therapeutic Effects: Increased cardiac output, increased blood pressure, and improved renal blood flow.

Adverse Reactions/Side Effects

CNS: headache. EENT: mydriasis (high dose). Resp: dyspnea. CV: arrhythmias, hypotension, angina, ECG change, palpitations, vasoconstriction. GI: nausea, vomiting. Derm: piloerection. Local: irritation at IV site.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Assess blood pressure (BP) and compare to normal values (See Appendix F). Report whether drug therapy is successful in normalizing BP in patients with shock and other cardiac conditions.

• Assess heart rate, ECG, and heart sounds, especially during exercise (See Appendices G, H). Report any rhythm disturbances or symptoms of increased arrhythmias, including palpitations, chest discomfort, shortness of breath, fainting, and fatigue/weakness.

• Monitor urine output whenever possible, and report decreased urine output, cloudy urine, or sudden weight gain due to fluid retention.

• Monitor signs of peripheral vasoconstriction, such as extreme coldness in the hands and feet, cyanosis, and muscle cramping. Notify physician of severe or prolonged signs of vasoconstriction.

• Monitor IV injection site for pain, swelling, and irritation. Report prolonged or excessive injection-site reactions to the physician.

Interventions

• Because of an increased risk of cardiac arrhythmias and compromised cardiac output, use caution during aerobic exercise and endurance conditioning. Terminate exercise if patient exhibits untoward symptoms (chest pain, shortness of breath, etc.) or displays other criteria for exercise termination (see Appendix L).

Patient/Client-Related Instruction

• Instruct patient or family/caregivers to report other troublesome side effects such as severe or prolonged headache, dilated pupils (mydriasis), or GI problems (nausea, vomiting).

Pharmacokinetics

Absorption: Administered IV only, resulting in complete bioavailability.

Distribution: Widely distributed but does not cross the blood-brain barrier.

Metabolism and Excretion: Metabolized in liver, kidneys, and plasma.

Half-life: 2 min.

Contraindications/Precautions

Contraindicated in: Tachyarrhythmias; Pheochromocytoma; Hypersensitivity to bisulfites (some products).

Use Cautiously in: Hypovolemia; Myocardial infarction; Occlusive vascular diseases; Geri: Older patients may be ...