Nitroglycerin Dosing in Critical Care Settings
The typical intravenous nitroglycerin dosing range in critical care settings is 10-200 mcg/kg/min, with initial dosing of 10-20 mcg/min and titration in increments of 5-10 mcg/min every 3-5 minutes until desired clinical response is achieved. 1, 2
Initial Dosing and Titration
- Start with 10-20 mcg/min via continuous infusion using non-absorbing tubing 2
- Titrate by increasing 5-10 mcg/min every 3-5 minutes based on clinical response 1, 2
- If no response at 20 mcg/min, increments can be increased to 10-20 mcg/min 2
- For hypertensive emergencies, nitroglycerin should be initiated at 5 mcg/min and increased in increments of 5 mcg/min every 3-5 minutes as needed 1
Maximum Dosing
- The maximum recommended infusion rate is typically 200 mcg/min 1, 2
- Higher doses up to 400 mcg/min may be used in certain clinical situations with careful monitoring 2, 3
- When doses exceed 200 mcg/min, consider alternative vasodilators as higher doses increase the risk of hypotension 1
Monitoring and Safety Parameters
- Maintain systolic blood pressure (SBP) >110 mmHg in previously normotensive patients 2
- In hypertensive patients, do not reduce SBP by more than 25% within the first hour 1
- Avoid use in patients with SBP <90 mmHg or 30 mmHg below baseline 2
- Continuous BP monitoring is recommended; arterial line placement is advised for higher doses or borderline BP 1
- Contraindicated after use of sildenafil within 24 hours or tadalafil within 48 hours due to risk of profound hypotension 2
Clinical Considerations
- Tachyphylaxis (tolerance) typically develops after 24-48 hours of continuous therapy, requiring dose adjustments 1, 2
- Use with extreme caution in patients with right ventricular infarction due to preload dependency 2
- Avoid in patients with advanced aortic stenosis 1
- Higher doses (>10 mcg/kg/min) may be needed to overcome tachyphylaxis 4
Special Populations
- In acute pulmonary edema with hypertension, higher doses may be required for rapid preload and afterload reduction 5
- For refractory angina, doses averaging 140 mcg/min have been effective in reducing episodes of rest angina 6
Common Pitfalls
- Using absorptive tubing materials can reduce delivered dose
- Failure to recognize tolerance development after 24 hours of continuous infusion 2, 7
- Inadequate dose titration for clinical effect
- Excessive hypotension can occur with rapid titration, especially in volume-depleted patients 1
- Headache is a common side effect that may require symptomatic management 1
By following these guidelines, nitroglycerin can be safely and effectively administered in critical care settings for management of hypertensive emergencies, acute coronary syndromes, and acute heart failure.