2006 OPEN FORUM Abstracts
MUCUS SHIFTS ACCORDING TO EXPIRATORY/INSPIRATORY FLOW RATIO.
Marcia Volpe RPT, Alexander Adams FAARC, RRT,
John Marini MD, Healthpartners/Regions
Hospital,
St. Paul
,
Minnesota
and
Sao
Paulo
,
Brazil
.
Background: Mucus retention and immobility in ventilated patients is a serious,
rarely-studied clinical problem. An established method does not exist for evaluating
factors that affect mucus movement within airways. Simply measuring the leading
edge of mucus movement in an airway simulation circuit may not reflect the overall
influence of factors such as ventilator settings, mucus viscosity or lung
impedance. In this study we studied whether expiratory/inspiratory flow
relationships would impact net mucus movement.
Methods: A clear tubing circuitry was assembled for imaging of mucus movement by a 12 mega
pixel camera (
Olympus
). A software program, Sigmascan,
analyzed net mucus movement relative to the injection point. One ml of mucus
stimulant mixed with green dye was injected into the circuitry. A Test Lung (Michigan Instruments, compliance
= 0.02) was ventilated via the circuitry at VT =300 ml, f =15/min
and inspiratory flow set to establish expiratory/inspiratory flow ratios of
1.8, 1.4, and 0.9.
Results: The center
of mucus mass moved away from the lungs (positive mm in figure) when expiratory
flow exceeded inspiratory flow at ratios of 1.8 and 1.4. At a greater
inspiratory flow (ratio of 0.9), mucus moved toward the lungs (negative mm in figure).
Conclusions: We describe a method
for assessing factors that may affect mucus movement within airways. Mucus
movement was influenced by the ratio of expiratory/inspiratory airflows. The
affect of ventilator settings on airflow profiles and, subsequently, mucus
movement should be considered in managing ventilatory
support.