3.27 Apnea Test To Assess Brainstem Function
Category: UWHC Patient Care Policy
Effective Date: April 25, 2016
Manual: Respiratory Care Services
Section: Patient Assessment
A tool used to aid in the clinical diagnosis of brain death. When brain death is suspected and the patient
has not exhibited any respiratory effort with a normal PaCO2. A positive test supports the diagnosis of
brain death. A negative test does not support the diagnosis of brain death.
A. Patient assisting with ventilation.
B. Patients with marginal oxygenation as determined by attending physician.
C. PaCO2 δ 35 mmHg.
D. Presence of confounding condition as determined by attending physicians:
1. Hypothermia – core temperature less than 32.3 θ in pediatrics.
2. Hypothermia – core temperature less than 36.5 θ (or 97 degrees F) in adults
A. All patients will be assessed by the Respiratory Care Practitioner (RCP).
B. Therapy will be provided in accordance with a provider’s order.
C. A RCP, physician, and nurse should be present throughout the test.
D. The patient will be monitored by pulse oximetry and ECG.
E. PICU patients will not have apnea test performed on the ventilator.
2. Appropriate size suction catheter for artificial airway.
4. O2 tubing
1. O2 tubing
2. Anesthesia bag
3. Oxygen flowmeter
A. Review and acknowledge provider’s order.
B. Review patient’s chart.
C. Obtain the appropriate equipment.
D. Introduce yourself to the family and explain the reason for the procedure.
E. Assure that there are no contraindications to proceed with test.
F. Normalize the PaCO2 to a range of 35-45 mmHg range to perform test.. If PaCO2 is already
higher than 35-45, maintain at current level.
G. Assess ventilator sensitivity to ensure that no auto-triggering or self-cycling is occurring.
H. Obtain an arterial blood gas within 1 hour prior to beginning apnea test.
I. Pre-oxygenate patient with 100% FIO2 for at least 30 minutes prior to test while on mechanical
ventilation. Begin Test:
1. Adults: Disconnect patient from mechanical ventilator and insert suction catheter
(with the sideport taped over) three-fourths of the way into the patient’s artificial airway and
attach to oxygen running at 6 lpm.
2. Pediatrics: Disconnect patient from the ventilator, deliver 100% O2 via an anesthesia bag
connected to the endotracheal tube. Warning: CPAP alone does not accomplish adequate
a. Infants less than 2 years old: anesthesia bag flow at 1-3 lpm
b. Greater than 2 years of age: anesthesia bag flow at 6 lpm
J. Look closely for respiratory movements (abdominal or chest excursions that produce adequate tidal
volumes). If respiratory movements are observed, the apnea test is complete and the result does not
support the diagnosis of brain death.
K. Monitor Cardiac and hemodynamic stability. If during testing the systolic blood pressure
1. Pediatric: hypotensive for age determined by MD.
2. Adult: less than or equal to 90 mm Hg or the pulse oximeter indicates significant oxygen
desaturation and cardiac arrhythmias are present; immediately draw an arterial blood sample and
re-establish mechanical ventilation.
L. Measure arterial PO2, PaCO2, and pH at designated times.
1. Adults: Measure approximately 8 minutes into testing.
2. Pediatrics: Measure at 5-10 minutes into testing unless patient decompensates or has
M. Place the patient back on mechanical ventilation when test is completed.
N. The apnea test result does support the diagnosis of brain death if:
1. Adult: PaCO2 is greater than or equal to 60 mmHg and no respiratory efforts are observed, or
PCO2 increase is > 20 mmHg over baseline normal PCO2.
2. Pediatric: PaCO2 is greater than or equal to 20 mmHg over patient specific normal
baseline PaCO2 and no respiratory efforts are observed.
O. The apnea test result is indeterminate and an additional confirmatory test can be considered if:
1. Adult: PaCO2 is less than 60 mmHg
2. Pediatrics: PaCO2 is less than 20 mmHg over patient specific normal baseline PaCO2.
P. If the PCO2 has not risen to the desired target range, the apnea test should be repeated, this time for ten
American Academy of Neurology, 2010
Approved by Director and Medical Director of Respiratory Care:
A copy of this Policy & Procedure is available in the Respiratory Care Office [E5/489].