TABLE 1

Principal characteristics of conventional home care ventilation and the newer dual volume-targeted pressure-controlled noninvasive ventilation modes

Mode	Pressure-targeted	VTPCV
Mode	Pressure-targeted	V_T-targeted	V_′A-targeted
Definition	APCV; PSV	Volume-targeted PSV targeting V_T (e.g. AVAPS, Phillips Respironics®; V_T Smart Eove®)	Volume-targeted PSV targeting V_′A (e.g. iVAPS, ResMed®)
Controlled variable	Inspiratory pressure	Minimal and maximal inspiratory pressure (below or above EPAP possible)	Minimal and maximal inspiratory pressure (above EPAP only)
Baseline variable	ZEEP or a given EPAP^#	ZEEP or a given EPAP^# Alternatively, automatic EPAP adjustment	ZEEP or a given EPAP^# Alternatively, automatic EPAP adjustment
Trigger variable	Pressure and flow in active respiration Time in passive respiration	Pressure and flow in active respiration Time in passive respiration	Only flow trigger is available in active respiration Time in passive respiration
Cycling variable	Time or a percentage of inspiratory flow decay (PSV or any other pressure-controlled flow-cycled mode)	Time or a percentage of inspiratory flow threshold according to the manufacturer's algorithm Inspiratory time depends on a given set t_I, a t_I_min or an I/E ratio	The percentage of inspiratory flow threshold is always the first cycling factor Time cycling depends on a given set t_I_min or t_I_max
V_T	Variable according to airway impedance and patient effort	A minimum average V_T is maintained	A V_T value to achieve the preset V_′A is maintained
Alveolar ventilation	Influenced by patient effort and respiratory frequency	Influenced by patient effort and respiratory frequency	Maintained constant at set target V_′A
Pressure ramp profile	Settable^¶	Settable	Settable
Unintentional leak compensation	Good for mild to moderate leaks	Good for mild to moderate leaks	Good for mild to moderate leaks
Advantages	Leak compensation Flow adaptability to patient requirements	Guarantees a minimal average V_T	Guarantees a minimal average V_′A
Disadvantages	No guarantees for a certain V_T	V_T under- or over-estimation Overshooting after a disruption cessation	V_′A under- or over-estimation
Used circuits	Nonvented (exhalation valve) or intentional leak “vented” circuit	Unvented or intentional leak “vented” circuit. AVAPS (Philips Respironics^®) uses only a “vented” circuit	Intentional leak “vented” circuit only

VTPCV: volume-targeted pressure-controlled ventilation; V_T: tidal volume; V_′A: alveolar ventilation; APCV: assisted pressure-controlled ventilation; PSV: pressure-supported ventilation; AVAPS: average volume assured pressure support; iVAPS: intelligent volume assured pressure support; EPAP: expiratory positive airway pressure; ZEEP: zero end expiratory pressure; t_I: inspiratory time; I/E ratio: inspiratory/expiratory ratio. ^#: all ventilators using an intentional leak “vented” circuit have by default a certain level of EPAP. ^¶: pressure ramp represents the time taken by the ventilator to reach the set inspiratory pressure. In a pressure-controlled flow cycled breath, the ventilator setting may modify inspiratory time and overall inspiratory flow.