Parameters for Holding IV Metoprolol
IV metoprolol should be held if the patient has any of the following: heart rate less than 50 beats per minute, systolic blood pressure less than 90 mmHg, PR interval greater than 0.24 seconds, second or third-degree heart block, signs of heart failure, evidence of low output state, or increased risk for cardiogenic shock. 1
Specific Holding Parameters
Hemodynamic Parameters
- Heart rate: Hold if < 50 beats per minute 1
- Blood pressure: Hold if systolic BP < 90 mmHg 1
- Signs of shock: Hold if evidence of low-output state (e.g., oliguria) 1
Cardiac Conduction Issues
- PR interval: Hold if > 0.24 seconds (marked first-degree AV block) 1
- Heart block: Hold if any form of second or third-degree AV block without functioning pacemaker 1
Cardiac Function Concerns
- Heart failure: Hold if signs of heart failure (e.g., rales, S3 gallop) 1
- Cardiogenic shock risk: Hold if patient has risk factors for cardiogenic shock 1
Risk Factors for Cardiogenic Shock
The more risk factors present, the higher the risk of developing cardiogenic shock:
- Age > 70 years
- Systolic blood pressure < 120 mmHg
- Sinus tachycardia > 110 bpm or heart rate < 60 bpm
- Increased time since onset of symptoms (for STEMI patients) 1
Respiratory Considerations
- Reactive airway disease: Hold if active asthma or reactive airway disease 1
- For patients with mild wheezing or history of COPD, consider reduced dosing rather than complete avoidance 1
Monitoring During IV Administration
When administering IV metoprolol, the following monitoring is essential:
- Continuous ECG monitoring
- Frequent blood pressure checks
- Heart rate monitoring
- Auscultation for rales and bronchospasm 1
Dosing Considerations
Standard IV metoprolol administration involves:
- 5 mg increments by slow IV administration (over 1-2 minutes)
- Repeated every 5 minutes to a total initial dose of 15 mg
- Monitor vital signs between doses 1, 2
Special Populations
- Hepatic impairment: Blood levels likely to increase substantially; use with caution 2
- Elderly patients: Use lower initial doses due to greater frequency of decreased hepatic, renal, or cardiac function 2
IV metoprolol is an effective medication for rate control in various cardiovascular conditions, but careful attention to these holding parameters is essential to prevent adverse outcomes related to bradycardia, hypotension, and worsening heart failure.