Apnea Testing for Brain Death Determination

Pre-Test Preparation

• Clinical and Neuroimaging Confirmation: Ensure that the patient has progressed to brain death.
• Environmental and Patient Preparation:
  • Patient should be euthermic.
  • Patient should be normotensive, possibly requiring vasopressors and fluid resuscitation.
  • Patient should be hyper-oxygenated on 100% oxygen.
  • Respiratory rate should be decreased to achieve normal pCO2 levels for at least 10 minutes.

Baseline Measurements

• Send baseline arterial blood gas:
  • Look for normalized CO2 (at least 40 mm Hg).
  • High oxygen levels (>200 mm Hg).

Equipment and Oxygen Delivery

• Insufflation Catheter: Prepare to deliver 100% oxygen at 4-6 L/min from the wall oxygen.
  • Avoid higher flow rates to prevent CO2 washout.
  • Expected CO2 rise: 2-4 mm Hg per minute in euthermic apneic patient.

Test Duration

• Apnea test should last at least 5-10 minutes to achieve CO2 > 60 mm Hg.
  • Typically recommended duration: at least 8 minutes, longer if patient is stable.

Procedure

• Disconnect Mechanical Ventilator:
  • Disconnect ventilator tubing from ET tube.
  • Turn off ventilator to avoid alarms.
• Oxygen Delivery:
  • Turn wall oxygen to 4-6 L/min.
  • Connect taped suction catheter to wall oxygen.
  • Insert catheter into ET tube for apneic oxygenation.
• Monitor Patient:
  • Bare the chest to observe for spontaneous respirations.
  • Have vasopressors available for hypotension.
  • Abort test if spontaneous respirations, hypoxemia (O2 saturation < 85% for >30 seconds), or intractable hypotension (systolic BP < 90 mm Hg) occur.

Post-Test Actions

• Maintain test duration of at least 8 minutes if no complications arise.
• Send final blood gas before reconnecting the mechanical ventilator.
• Reconnect ventilator and set respiratory rate to 16-20 breaths per minute to blow off CO2 and avoid post-test hypotension.
• Positive Apnea Test: If CO2 rise is demonstrated without respirations, pronounce death at the documented time.