1995 OPEN FORUM Abstracts
Success Predictors For Passy-Muir Speaking Valve Use In A Pediatric Population: A Method Evaluation
Liz B. Trotter, B.S., R.R.T., C.P.F.T., Perinatal Pediatric Specialist. The Children's Seashore House, Philadelphia, PA
INTRODUCTION: After discussing the anatomy and flow dynamics of pediatric tracheas with two pediatric critical care physicians, it was hypothesized that an audibly measured leak of 15 centimeters of water pressure (cmH20) or less and/or an electronically measured leak of 50% or greater should predict successful use of the Passy-Muir valve. This size gas leak should support sufficient gas passage around the tube without producing excessive PEEP. The Passy-Muir Speaking Valve is a one way valve intended for use with tracheostomized patients of all age groups to improve speech. Speech pathologists have incorporated use of the valve in their treatment plans for patients with swallowing discoordination. A method to predict successful use of the speaking valve was needed to prevent patient fear, distress and trauma, and future non-compliance. METHOD: Six non-mechanically ventilated tracheostomized patients between six months and five years of age were studied. Sample size was limited by our institution's total number of tracheostomized children who were not mechanically ventilated. The gas leak around each patient's tracheostomy tube was evaluated audibly with a flow-inflating resuscitation bag with an in-line pressure manometer. Electronic evaluation of the tube leak was performed in accordance with the Bear Neonatal Volume Monitor User Manual and results were reported as a percentage (expired tidal volume/inspired tidal volume=% leak). Audible evaluation with the resuscitation bag was achieved by placing a stethoscope over each patient's trachea while gradually tightening the resuscitation bag valve to achieve increasingly higher airway pressures. The pressure at which the leak was heard was recorded in cmH20. Patients with audibly measured leaks of 15 cmH20 or less and/or an electronically measured leak of 50% or greater were hypothesized to have a high probability of success with the Passy-Muir Valve. This hypothesis was tested via institution of the valve. RESULTS/EXPERIENCE: Successful outcomes were predicted in all six cases when the patients' measured parameters positively correlated with the defined criteria for predicting success or failure. Other monitoring systems, such as end-tidal CO2 and Sp02 were initially used to evaluate patient response. Monitoring Sp02 was abandoned, because patients often failed acutely before a desaturation could be measured. These patients were often agitated and unmeasurable using oximetry. End-tidal C02 was only minimally acceptable and was used secondarily as a confirmation of success. Select patients with established language skills were tested with a speech pathologist present. These patients needed reassurance and coaching to attempt verbalization. The session was disrupted when the end-tidal monitor was placed in the patient's mouth. CONCLUSION: Identification of potential success with leak measurements is a valuable tool when instituting the Passy-Muir Valve. Potential for patient distress and harm is greatly reduced and patient trust is protected. Although this study reflects only non-mechanically ventilated patients, mechanically ventilated patients could be studied in a similar fashion. A substantial leak is necessary for use of the Passy-Muir Valve with a ventilator, because all exhalation occurs around the tube through the patient's natural airway. Passy-Muir, Inc. recommends the tracheal tube only occupy one third of the tracheal lumen when used with a mechanical ventilator. A non-invasive assessment of tube size would enable the practitioner to be confident in use of the Passy-Muir Valve in both ventilated and non-ventilated patient populations.