1998 OPEN FORUM Abstracts
REMOVAL OF INNER CANNULA DECREASES WORK OF BREATHING (WOB) AND AIRWAY RESISTANCE (Raw) IN TRACHEOSTOMY TUBES.
Tony Cowan BS, Cyndi Gegenheimer BS, Timothy B. Op't Holt Ed.D., R.R.T., Dept. of Cardiorespiratory Care, Seth Izenberg, MD, Dept. of Surgery, University of South Alabama, Mobile, AL.
INTRODUCTION: Tracheotomy has been used to help liberate hard to wean patients from mechanical ventilation. Some patients have been observed, in spite of already having a tracheostomy tube, who fail to be liberated from the ventilator after several attempts. It was hypothesized that by removing the inner cannula from the tracheostomy tube, the WOB and Raw may be decreased enough to facilitate more successful weaning. The hypothesis was tested by measuring the change in WOB and Raw of tracheostomy tubes when the inner cannula was removed using a lung model. Methods: A mechanical lung model was developed using the Michigan Instruments 2600i dual adult training test lung to simulate a spontaneously breathing patient. WOB and Raw were measured with the Bicore CP-100 (Bear Medical Corp., USA) in sizes 6, 8, and 10 non-fenestrated tracheostomy tubes with the inner cannula in and out. Breathing conditions varied using tidal volumes (Vt) of 300 and 500 cc matched with respiratory rates (RR) of 12 and 24 bpm by using the Emerson 3MV-PED ventilator to reproduce spontaneous breathing through the right side of the test lung.
Results: The WOB and Raw in all breathing conditions through the three tracheostomy tubes were significantly reduced (p < .05) when the inner cannula was removed. Conclusions: Recent literature states that normal WOB is 0.3 to 0.6 Joules/L. The WOB of the three tracheostomy tubes exceeded normal when the Vt and RR were the highest. Removing the inner cannula may reduce the WOB and Raw significantly enough in patients to facilitate successful weaning from the ventilator. Further study of the clinical significance of removing the inner cannula on WOB and Raw in the patient is being planned.
The 44th International Respiratory Congress Abstracts-On-Disk®, November 7 - 10, 1998, Atlanta, Georgia.