The Science Journal of the American Association for Respiratory Care

2012 OPEN FORUM Abstracts

ELECTRICAL IMPEDANCE TOMOGRAPHY USED TO MONITOR REGIONAL VENTILATION DIFFERENCES OF MECHANICAL AND SPONTANEOUS BREATHS IN AN ARDS CASE.

John S. Emberger1, Joel M. Brown II1, John Getchell2, Gerard Fulda2, Vinay Maheshwari3; 1Respiratory Care, Christiana Care Health System, Newark, DE; 2Surgery, Christiana Care Health System, Newark, DE; 3Medicine, Christiana Care Health System, Newark, DE

INTRODUCTION: Electrical impedance tomography (EIT) monitors regional lung ventilation via an electrode chest belt measuring impedance. EIT software can compare four Regions of Interest (ROI). We conducted an IRB approved blinded study of EIT on ALI/ARDS patients (EIT Evaluation Kit 2, Draeger Medical, Luebeck Germany). CASE SUMMARY: A 32 year old female in a motor vehicle crash presented with multiple fractures and a severe chest contusion which developed into ARDS. EIT monitoring was performed on day 10 of admission after informed consent. Data on the day of EIT monitoring: APRV mode, Pressure High=24cmH2O, Pressure Low=0 cmH2O, Time High=14 seconds, Time Low=1.0 seconds, FiO2=50%. MAP=23cmH2O, Ve=9.5 LPM, RR=24. PaO2/FiO2 ratio=140. Her chest x-ray and CT scan both were consistent with ARDS. The patient was spontaneously breathing on APRV. EIT data was analyzed in 4 ROI slices of the lung (see the figure). % ventilation for the ROI slices were averaged for 20 spontaneous breaths versus 20 mechanical breaths. % ventilation of ROI slices 1 through 4 were as follows: Mechanical breaths = 19.5+1.7%, 44.5+1.5%, 26.3+2.7% and 9.1+0.5% Spontaneous breath = 8.8+1.5%, 33.0+2.6%, 43.9+3.4% and 11.8+0.8% Mechanical breaths ventilated the anterior regions (ROI 1 and 2) with 64% of the ventilation while spontaneous breaths ventilated the anterior regions with 41.8%. Mechanical breaths ventilated the posterior regions (ROI 3 and 4) with 35.3% of the ventilation while spontaneous breaths ventilated the posterior regions with 55.7%. The blinded EIT monitoring had no direct effect on this patientÂ’s care. The patient progressed in recovery and was discharged to a short term rehabilitation facility on day 39 of admission. DISCUSSION: In this case of ARDS during APRV with spontaneous breathing, EIT demonstrated differences in regional lung ventilation between mechanical and spontaneous breaths. In this case on APRV, mechanical breaths ventilated a larger portion of anterior lung and spontaneous breaths ventilated a larger portion of posterior lung. Also, spontaneous breaths exhibited better balance of ventilation in anterior versus posterior regions than the mechanical breaths. Balancing ventilation in different regions of the lung could play a role in lung protection and EIT could be a valuable device to monitor regional lung ventilation in the future. Sponsored Research - None EIT image showing regional ventilation in four Regions of Interest (ROI) slices from anterior to posterior of a patient with ARDS.