Table 1 Definition of terms used
From: Respiratory entrainment related reverse triggering in mechanically ventilated children
Term Definition | |
|---|---|
Coefficient of variation | Statistical measure used to assess the relative variability of a dataset expressed as a percentage. CoV = (standard deviation/mean) * 100. |
Double triggering | Two consecutive ventilator cycles separated by a short expiratory time, i.e., half of the inspiratory time or less. |
Entrained reverse triggering | Breathing effort after the start of a ventilator cycle in a regular pattern (four consecutive reverse triggered breaths). Pattern occurring in a 1:1, 1:2 or in 1:3 ratio. During entrainment the patient is cycling between patient triggered and reverse triggered breaths. Breathing pattern is showing low variability (i.e. coefficient of variation < 15%). |
Non-entrained reverse triggering | Breathing effort after the start of a time triggered mandatory breath occurring as a single event. |
Patient-triggered breath | Patient effort (increase in electrical activity of the diaphragm/negative deflection in the oesophageal pressure tracing) followed by a ventilator pressurization. |
Phase-angle | Calculation to describe the time duration or delay between a patient effort and the initiation of the ventilator pressurization. A phase angle of 0° means that the patient effort starts at the same time as the initiation of the ventilator pressurization. A phase angle of 180° means that the patient’s effort starts halfway between the start of two mandatory breaths. Phase angle = (start patient effort – start ventilator pressurization/breathing cycle) * 360°. |
Respiratory entrainment | Form of neuromechanical coupling in which the subject’s breathing frequency matches an external stimulus creating a fixed patient respiratory rhythm with less variability (i.e. coefficient of variation < 15%). |
Reverse triggering | Patient effort generated after a time triggered mandatory breath. |
TTOTMECH | Duration of the ventilator breath. Time (sec) period between the start of a time cycled mandatory breath until the start of the consecutive time cycled mandatory breath |
TTOTNEU | Duration of a patient triggered ventilator cycle. Time (sec) between the start of a patient effort (based on dEMG signal or oesophageal pressure) until the start of the consecutive patient effort |
Time triggered mandatory breath | Ventilator pressurization without any signs of a patient effort. |