Do patients need to be Nil Per Os (NPO) for cardiac Magnetic Resonance Imaging (MRI)?

NPO Requirements for Cardiac MRI

Patients do not need to be NPO (nil per os) for standard cardiac MRI examinations. This is supported by current practice guidelines and recent quality improvement initiatives.

Understanding Cardiac MRI Requirements

Cardiac MRI is a non-invasive imaging modality that provides detailed anatomical and functional assessment of the heart. Unlike procedures requiring sedation or anesthesia, standard cardiac MRI examinations do not pose aspiration risks that would necessitate fasting.

Key Considerations:

• Standard Cardiac MRI: No NPO requirement

  • Does not involve sedation in most cases
  • Does not carry significant aspiration risk
  • Patient needs to be able to follow breathing instructions and hold still 1

• Special Circumstances: NPO may be required if:

  • The patient requires sedation or general anesthesia (e.g., severe claustrophobia)
  • The cardiac MRI is combined with another procedure requiring fasting
  • Stress cardiac MRI with pharmacologic agents is planned

Evidence Supporting No NPO Requirement

Recent quality improvement initiatives have demonstrated that many diagnostic imaging procedures, including MRI, do not require NPO status 2. These initiatives have successfully reduced unnecessary fasting requirements without increasing complications or procedural delays.

The American College of Cardiology Foundation (ACCF) guidelines for cardiac MRI do not list NPO status among their requirements or assumptions for performing cardiac MRI 1. Instead, they focus on other patient requirements such as:

• Ability to hold still
• Ability to follow breathing instructions
• Absence of contraindications such as certain metallic implants or severe claustrophobia 1

Important Patient Preparation Considerations

While NPO status is not required, other preparation aspects are important:

1. Screening for contraindications:

   • Certain pacemakers/defibrillators (though many newer devices are MRI-conditional) 3, 4, 5
   • Metallic implants or foreign bodies
   • Severe claustrophobia
   • Renal insufficiency if contrast is planned (creatinine >1.8 mg/dL) 1

2. Medication considerations:

   • Patients should take their regular medications with sips of water
   • For coronary MR angiography, patients may need to take nitroglycerin 1

3. Technical requirements:

   • Heart rate control (ideally <70 beats/min) may be needed for certain sequences 1
   • Patient should be able to hold their breath for short periods and follow instructions

Conclusion

Cardiac MRI does not require patients to be NPO unless specific circumstances dictate the need for sedation or anesthesia. This approach aligns with current evidence-based practice and helps improve patient comfort and satisfaction while maintaining safety.