The Science Journal of the American Association for Respiratory Care

1996 OPEN FORUM Abstracts

EFFECT OF VENTILATION TECHNIQUE EMPLOYED ON TIDAL VOLUME (V_{T}) DELIVERY AND GASTRIC INSUFFLATION (GI) DURING SIMULATED PREHOSPITAL MASK VENTILATION.

Robert S Campbell RRT, Richard D Branson RRT, Jay A Johannigman MD, Kenneth Davis Jr. MD. University of Cincinnati Med Cntr, Cincinnati, OH 45267.

BACKGROUND: Mouth-to-mouth and mouth-to-mask ventilation are fast becoming dinosaurs in the prehospital environment even among trained professionals. This is mainly due to concerns over infection control issues. Most patients presenting to our emergency department without an instrumented airway are receiving bag-valve-mask ventilation (BVMV) from a paramedic or EMT. Though each squad is equipped with a transport ventilator, it's use is generally reserved for intubated patients. This study was designed to compare the efficacy of mask ventilation provided by BVM, two commercially available demand valves (DV), and a transport ventilator when used by paramedics and EMT's. METHOD: Eleven paramedics ventilated a lung model consisting of a mannequin head, tracheal model, simulated esophagus, and training test lung using each ventilation technique for 10 minutes. A disposable adult anesthesia mask (King Systems Corp.) was used for all tests. A disposable resuscitation bag (DMR II, Nellcor/Puritan-Bennett) was used to provide BVMV. Two manual pneumatic demand valves were used (LSP Model 575 and CPR Medical devices Oxylator EM-100) to provide manual triggered ventilation. An Impact 750 transport ventilator was used to provide ventilator to mask ventilation. Lung compliance was set at 0.04 L/cmH_{2}O and resistance at 5 cmH_{2}O/L/s. Paramedics were instructed to ventilate the test lung with an 800 mL V_{T} at a rate of 12. During each test period, delivered V_{T}, respiratory frequency (f), GI volume, and airway pressures were measured and recorded for each breath using a test lung software package. Mean values for each minute were calculated from these measurements. Results: Delivered V_{T} and GI volume using each technique are shown at 1 and 10 minutes. Results are mean (mL) ± SD.

Technique V_{T}-1 min V_{T}-10 min GI-1 min GI-10 min

BVM 627±147 588±162 117±24 97±21

LSP-DV 735±113* 702±113* 65±20 56±19

EM-100-DV 781±88* 773±108* 91±22 97±21

Impact 750 870±167*# 838±148*# 4±1*#$ 6±2*#$

* p < 0.05 vs BVM. # p < 0.05 vs LSP. $ p < 0.05 vs EM-100.

Mean PIP (cmH_{2}O) using each technique was: BVM = 27.1, LSP = 20.5, EM-100 = 22.3, Impact 750 = 17.7. DISCUSSION: Though BVM is the most commonly used technique, it resulted in significantly lower V_{T} delivery compared to all other techniques tested. GI was highest using BVM technique due to the associated higher PIP. CONCLUSION: Both manually triggered demand valves and the transport ventilator provided superior V_{T} delivery compared to BVM, but only the transport ventilator lowered the GI volume.

Reference: OF-96-164

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