Evaluation of Mechanical Ventilator Alarm to Detect Accident Decannulation During Pediatric Mechanical Ventilation: A Simulated Study

Abstract

Background: Accidental decannulation places a subsequential risk of hypoventilation and cardiopulmonary arrest in tracheostomized children requiring mechanical ventilation. Delayed or undetected alarms for accidental decannulation were found in previous studies and our practice. Low minute ventilation and circuit disconnection alarms are commonly used in our patients with home mechanical ventilation. The purpose of this study is to evaluate ventilator alarm function in detecting accidental decannulation among different configurations.

Methods: The simulated decannulation events were performed using a 3-D printed airway model, tracheostomy tubes, ventilator types, and ventilator alarms. There were 45 configurations in total. The distal end of airway model with tracheostomy tube was connected to a 0.5 L test lung. The ventilators were set in a pressure-controlled intermittent mandatory ventilation with set-point targeting schemes (PC-IMVs,s). The airway model and test lung were ventilated through the tracheostomy tube with cuff inflated. To simulate decannulation, the tracheostomy tube cuff was deflated and the tube was removed away from the airway model. Three sizes of tracheostomy tube were tested connecting with different ventilators. Fail-to-detect decannulation was defined when alarms were not activated after decannulation for 120 s. Durations to detect simulated decannulation events and were recorded.

Results: 44.4% (20/45) of configurations fail-to-detect decannulations were found among 5 ventilators. Durations to activated circuit disconnect alarm in Trilogy EV300 connecting to the airway model with tracheostomy tube inner diameter (ID) of 3.5, 4.5, and 5.5 mm ranged from 12.5 to 14 s. Duration to activated circuit disconnect alarm in Astral 100 connecting to the airway model with tracheostomy tube ID of 3.5, 4.5, and 5.5 mm ranged from 4.5 to 8.5 s. Duration to activated circuit disconnect alarm in VOSCN connecting to the airway model with tracheostomy tube ID of 5.5 mm was 3 s.

Conclusions: The performance of ventilator alarm function to detect decannulation widely varied from low minute ventilation alarm, circuit disconnection alarm, ventilator type, and tracheostomy tube ID. In tracheostomized children using different ventilators, it is essential to understand and optimize ventilator alarms to timely detect accident decannulation.