RESUMO
BACKGROUND: Positive-pressure ventilators are equipped with low-inspiratory-pressure alarms to protect patients from hypoventilation. Small uncuffed tracheostomy tubes have a high resistance, and may not trigger these alarms during decannulation. STUDY OBJECTIVE: To determine whether ventilator low-inspiratory-pressure alarms are effective in detecting tracheostomy decannulation. DESIGN: We connected tracheostomy tubes of varying inner diameters (3.0 to 6.0 mm) to a home ventilator and simulated decannulation using low (tidal volume [VT], 600 mL; peak inspiratory pressure [PIP], 25 cm H(2)O), medium (VT, 800 mL; PIP, 30 cm H(2)O), and high (VT, 1,000 mL; PIP, 35 cm H(2)O) ventilator settings. RESULTS: When the ventilator low-inspiratory-pressure alarm was set at 4 cm H(2)O below the desired PIP, it failed to alarm for simulated decannulation of tracheostomy tubes < 4.5 mm on low and medium settings, and < 4.0 mm on high settings. When the ventilator low-inspiratory-pressure alarm was set at 10 cm H(2)O below the desired PIP, it failed to alarm with tracheostomy tubes < 6.0 mm. CONCLUSION: We conclude that ventilator low-inspiratory-pressure alarms fail to alarm during simulated decannulation with small tracheostomy tubes commonly used in children. We speculate that low-inspiratory-pressure alarms set at 4 cm H(2)O below the desired PIP will detect more decannulation than when set at 10 cm H(2)O below the desired PIP.
