RT Journal Article
SR Electronic
T1 Ventilation Patterns Influence Airway Secretion Movement
JF Respiratory Care
FD American Association for Respiratory Care
SP 1287
OP 1294
VO 53
IS 10
A1 Volpe, Marcia S
A1 Adams, Alexander B
A1 Amato, Marcelo B
A1 Marini, John J
YR 2008
UL http://rc.rcjournal.com/content/53/10/1287.abstract
AB BACKGROUND: Retention of airway secretions is a common and serious problem in ventilated patients. Treating or avoiding secretion retention with mucus thinning, patient-positioning, airway suctioning, or chest or airway vibration or percussion may provide short-term benefit. METHODS: In a series of laboratory experiments with a test-lung system we examined the role of ventilator settings and lung-impedance on secretion retention and expulsion. Known quantities of a synthetic dye-stained mucus simulant with clinically relevant properties were injected into a transparent tube the diameter of an adult trachea and exposed to various mechanical-ventilation conditions. Mucussimulant movement was measured with a photodensitometric technique and examined with image-analysis software. We tested 2 mucus-simulant viscosities and various peak flows, inspiratory/expiratory flow ratios, intrinsic positive end-expiratory pressures, ventilation waveforms, and impedance values. RESULTS: Ventilator settings that produced flow bias had a major effect on mucus movement. Expiratory flow bias associated with intrinsic positive end-expiratory pressure generated by elevated minute ventilation moved mucus toward the airway opening, whereas intrinsic positive end-expiratory pressure generated by increased airway resistance moved the mucus toward the lungs. Inter-lung transfer of mucus simulant occurred rapidly across the “carinal divider” between interconnected test lungs set to radically different compliances; the mucus moved out of the low-compliance lung and into the high-compliance lung. CONCLUSIONS: The movement of mucus simulant was influenced by the ventilation pattern and lung impedance. Flow bias obtained with ventilator settings may clear or embed mucus during mechanical ventilation.