Classifying different types of double triggering based on airway pressure and flow deflection in mechanically ventilated patients.
BACKGROUND
Double-triggering (DT) is a frequent type of patient-ventilator asynchrony and has potentially severe consequences, such as alveolar overdistention or the generation of intrinsic PEEP. However, the first breath of DT could be patient-triggered (DT-P), auto-triggered (DT-A), or ventilator-triggered (DT-V).


OBJECTIVE
To differentiate DT-P, DT-A, and DT-V using airway pressure or flow changes during the trigger-delay phase in ventilated patients.


METHODS
Fourteen mechanically ventilated patients with DT were included. All patients were on flow-triggered ventilation modes and received either continuous mandatory ventilation or pressure support ventilation. Breaths in which the first breath was associated with an esophageal pressure drop of > 1 cm H(2)O were categorized as DT-P. Breaths in which the first breath occurred at the ventilator set cycle were categorized as DT-V. Breaths in which the first breath occurred earlier than the ventilator set cycle without esophageal pressure drop were categorized as DT-A. The pressure drop and flow change at 0.13 s (PD(0.13) and F(0.13), respectively) in the trigger-delay phase were calculated from the nadir.


RESULTS
There were 507 double-triggered breaths: 271 DT-V (53%), 50 DT-A (10%), and 186 DT-P (37%). The PD(0.13) for DT-V, DT-A, and DT-P were 0.16 ± 0.12 cm H(2)O, 0.25 ± 0.17 cm H(2)O, and 1.34 ± 0.67 cm H(2)O, respectively. The F(0.13) for DT-V, DT-A, and DT-P were 2.11 ± 2.31 L/min, 2.64 ± 2.07 L/min, and 16.51 ± 8.02 L/min, respectively. The best discriminatory criteria for differentiating DT-P from DT-V and DT-A, based on the Youden index (sensitivity + specificity - 1) was PD(0.13) ≥ 0.49 cm H(2)O, which had a Youden index of 95%.


CONCLUSIONS
DT-P can be distinguished from DT-V and DT-A by using airway pressure deflections in the trigger-delay phase.
Chiali Hospital, Chiali Town, Tainan, Taiwan.
Kuang-Ming
KM
Liao
Chih-Ying
CY
Ou
Chang-Wen
CW
Chen
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000403:Airway Resistance / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011312:Pressure; D012372:ROC Curve; D012121:Respiration, Artificial / Q000295:instrumentation / Q000379:methods*; D012131:Respiratory Insufficiency / Q000503:physiopathology* / Q000628:therapy*; D012122:Ventilators, Mechanical