Arterial Blood Pressure Monitoring

 Arterial blood pressure monitoring

  • Invasive way to monitor blood pressure more accurately.
  • Ensure waveform is appropriate before interpreting pressures. BP can be artifactually low or high.
  • Pay attention to pulse pressure. Wide pulse pressure: Chronic anemia, PDA, vasodilatation. Narrow pulse pressure: Status asthmaticus, Cardiac tamponade, dehydration
  • Use heparinized normal saline to prevent clotting @ 1-2 cc/hr.
  • Add papaverine 30-60 mg to heparinized fluids to help with vasospasm.

 Central Venous Pressure Monitoring

 Central venous pressure monitoring

  • CVP reflects the amount of blood returning to the heart (preload).
  • Normal CVP tracing has 3 positive waves (a,c,and v) and 2 negative waves (x and y). The a wave is caused by atrial contraction, c wave by ventricular contraction against a closed tricuspid valve, and the v wave is caused by atrial filling. The x descent is due to tricuspid valve being pulled away from the right atrium by contracting ventricle, while the y descent occurs as tricuspid valve opens and blood enters the ventricle.
  • Normal CVP: 2-6 mmHg
  • Ensure CVP reading is obtained with appropriate leveling and at end expiration.
    High CVP: TR, TS, heart failure, elevated intrathoracic pressure
    Low CVP: Hypovolemia and distributive shock (anaphylaxis)
  • Use heparinized normal saline fluids @ 2-3cc/hr to prevent clotting.