The Science Journal of the American Association for Respiratory Care

2004 OPEN FORUM Abstracts

CASE STUDY COMPARING AIRWAY RELEASE VENTILATION (APRV) TO SYNCHRONIZED INTERMITTENT MANDATORY VENTILATION (SIMV) IN THE CRITICALLY ILL NEONATE

Christina B. Crooke BS, RRT, NPS, Betty L. Blake BS, RRT, NPS, Susan Aucott MD. The Johns Hopkins Hospital, Baltimore, Maryland

Introduction: The critically ill neonate at times requires mechanical ventilation directed towards multi-system support versus conventional mechanical ventilation. The use of APRV allows for alveolar recruitment while minimizing circulatory compromise.

Case Study: A 32 week neonate presents with tracheoesophageal fistula and ventricle septal defect. The neonate had an infarct in the right upper and right middle lobes of the lung which were removed on day of life (DOL) 38. On DOL 76, the ventilator settings increased to peak inspiratory pressure (PIP) 28 with positive end expiratory pressure(PEEP) 7, with no improvement in ventilation and oxygenation. Mean airway pressure (MAP) in SIMV was 15-16 mmHg. APRV was initiated using MAP of 25 mmHg. Additional settings included: pressure high 26, pressure low 2, time high 2.7 with a time low 0.2. The neonate’s capillary blood gas showed improvement in the carbon dioxide (CO2) level and improvement in the SpO2 on lower level on fraction of inspired oxygen (FiO2). As shown in the table, the patient required less sedation as ventilatory status improved.

MODE FiO2 TI/TE END PRESSURE PEAK MAP SPO2
SIMV .83 .50/.70 7 28 16 .94
  pH=7.32 pCO2=87 PO2=46 HCO2=43.8    
APRV .52 2.7/0.2 2 26 25 .94
  Ph=7.43 pCO2=71 PO2=47 HCO2=46.1    
APRV .50 2.2/0.2 2 25 23 .94
  pH=7.48 pCO2=39 PO2=108 HCO2=28.4    

Discussion: APRV uses continuous positive airway pressure levels to maintian oxygenation and time releases for CO2 removal. APRV allows for unrestricted, spontaneous breathing throughout the entire ventilatory cycle. Spontaneous breathing results in better ventilation-perfusion (VA/VQ) matching which in turn decreases intrapulmonary shunting. Within hours of initiating APRV the neonate showed marked improvement in ventilation and oxygenation at lower peak pressures.

Conclusion:
This particular case demonstrates that APRV may have alternative uses for the neonatal population with poor ventilatory status due to restrictive lung disease.

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