Maxim 10: A mode of ventilation is classified according to its control variable, breath sequence, and targeting scheme.

To classify a mode of ventilation we need to identify its:

1) Control variable, whether Pressure or Volume

2) The breath sequence employed, CMV / IMV / CSV

3) The primary breath targeting scheme (for CMV / IMV / CSV), and the secondary breath targeting scheme in IMV

The primary breath is defined as the only breaths that occur such as the mandatory breaths in CMV or the spontaneous breaths in CSV, or the mandatory breaths in IMV. Given that IMV allows for spontaneous breaths to occur in-between the mandatory breaths, the spontaneous breaths are assigned a secondary targeting scheme. The schemes can be denoted by single lower-case letters as below. Also for IMV, the type of IMV employed would be identified in parenthesis.

Targeting Scheme	Letter Code
Set-Point	s
Dual	d
Servo	r
Adaptive	a
Bio-Variable	b
Optimal	o
Intelligent	i

Examples:

[1] APV-SIMV on a Hamilton G5 (PRVC SIMV on a Servo-U): There is a set number of pressure controlled mandatory breaths with spontaneous breaths allowed to occur in between the IMV breaths. Given that the pressure is adjusted up or down based on the average tidal volume delivered for the IMV breaths, the ventilator is noted to be in adaptive targeting for those breaths. For the spontaneous "pressure support" breaths, the peak pressure is set by the operator and is hence utilizing set-point secondary targeting. The mode can hence be written out as PC-IMV(1)a,s. With the first lower case (denoting) the primary targeting scheme used for the IMV breaths, and the (s) used for the set-point targeting employed by the "pressure-support" breaths.

[2] APV-CMV on a Hamilton G5 (PRVC on a Servo-U): we know that it is in fact a pressure-control based breath (by reviewing pressure and flow scalars) with all breaths having a mandatory I-time regardless of whether they're patient triggered or ventilator triggered. We also know that the ventilator will adjust (adapt) the pressure up or down based on the average tidal volume of the last few breaths. The end result is PC-CMVa.

[3] SIMV-PC on a Servo-U, is a pressure controlled mode, with mandatory breaths and spontaneous breaths with set-point targeting. PC-IMV(1)s,s would be the designated mode.