| 11 th Annual Pediatric Critical Care Colloquium |
| Session/Time | Poster/Thu, 4:30 - 6:30 PM |
| Title | Use of Microcontroller to Trigger Portable Chest Radiography at End-Inspiration PA |
| Author | Bernard, SE Curtis |
| Affiliation | University of Alabama at Birmingham, Birmingham, AL |
| Introduction | The rapid ventilator rates used in pediatrics make difficult for portable chest radiographs to be exposed at end-inspiration, Limiting interpretation of the CXR- Subsequently, CXR's frequently have false positive readings,secondary to poor chest expansion. We have developed a device which incorporates a microcontroller core to expose portable chest radiographs at end-inspiraton on mechanically ventilated pa6ents. |
| Method | Amicroprocessorwasusedtouniteaninspiratorysi from a Servo-Venblator 900C (Siemens) to radiograph exposure with ar AiMX-4 (GE). Briefly, an inspiratory time out signal from the Siemens 900 C was used as an input to a PIC microprocessor (Microchip, Phoenix, AZ). At the user's signal, the microprocessor would then -6vate the x-ray rotor and synchronize radiograph exposure with end inspiration. Three lambs with oleic acid induced resticfive lung disease (a model of ARDS) had chest x-rays taken usina the device described above. Volume wntmi ventilation with a rate of 25 breaths/min, tidal volume of 10cc/kg, positive end expiratory pressure of 5 cm H20, and inspiratory time of 33% was used . In addition, peak inspiratory Dressums , mean airway pressure, and plateau pressure were recorded. ,X-ray exposure was recorded in relation to airway pressures u-sino, a entium 166 IBM-compatible computer using standard LabView software and acquisition devices (National Instruments, Austin, TX) and a photodiode based x-ray detection device (Carroll-Ramsy Associates, Berkeley, CA).The microcontroller was proarammed to activate the AMX-- during various phases durina, the ventilatory cycle including end-inspiration and 30 msecs into expiration.X-ray area was calculated usina Scion Image for Windows 5 (Scion Corporation, ' Frederick, Maryland), a Windo based image analysis proaram based on NIH image. |
| Result | Radiographic area obtained at end-inspiration using the microcontroller did not differ from those obtained using the ventilator's inspriatory hold feature. 14% (20/140ml) of the tidal volume had been exhalted at 30 msecs after end-inspiration. This was also associated with a differences in radiographic area of 6%. |
| Conclusion | Our device reliably obtains chest x-ray films a end-exposure. Delay of the x-ray exposure by as little as 30msecs can cause up to 6 % decreasein radiographic. |
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