From the Research
Hydralazine should be held when systolic blood pressure falls below 90-100 mmHg or diastolic blood pressure falls below 60 mmHg. This medication is an arterial vasodilator used to treat hypertension and heart failure, but excessive blood pressure lowering can lead to hypoperfusion of vital organs. When administering hydralazine, monitor blood pressure before each dose and withhold the medication if readings fall below these thresholds. After holding a dose, reassess the patient's blood pressure in 1-2 hours before considering administration of the next scheduled dose. Hydralazine works by directly relaxing vascular smooth muscle, which causes vasodilation and reduces peripheral resistance. This mechanism explains why excessive doses can cause significant hypotension, reflex tachycardia, and symptoms like dizziness, headache, or syncope. For patients with coronary artery disease, consider holding at higher thresholds (SBP <110 mmHg) as they may be more sensitive to reduced coronary perfusion 1.
Some of the adverse effects related to hydralazine that have been reported in the literature include reflex tachycardia, hemolytic anemia, vasculitis, glomerulonephritis, and a lupus-like syndrome 2, 3. Although there is insufficient evidence to conclude on the effects of hydralazine versus placebo on mortality, morbidity, withdrawals due to adverse effects, serious adverse events, or systolic and diastolic blood pressure, hydralazine may reduce blood pressure when compared to placebo in patients with primary hypertension 2, 3.
Key points to consider when holding hydralazine include:
- Monitor blood pressure before each dose
- Withhold the medication if readings fall below the thresholds
- Reassess the patient's blood pressure in 1-2 hours before considering administration of the next scheduled dose
- Consider holding at higher thresholds for patients with coronary artery disease
- Be aware of the potential adverse effects of hydralazine, such as reflex tachycardia and hemolytic anemia.
It is essential to prioritize the patient's safety and adjust the treatment plan accordingly, taking into account the potential risks and benefits of hydralazine therapy 4, 5.