Article Figures & Data
Figures
- Fig. 1.
Idealized airway pressure waveform, showing various conventions used for pressure parameters (see Table 1). Note that there are 2 ways to define the inspiratory pressure (blue) of a mandatory breath, and 4 ways to define the pressure support of a spontaneous breath (red). PEEP = positive end-expiratory pressure. CPAP = continuous positive airway pressure. P-low = low pressure.
- Fig. 2.
Airway pressure and simulated muscle pressure waveforms, illustrating synchronization of a mandatory breath in a bi-level mode. Detection of a patient signal (eg, flow or pressure change) within the trigger window initiates a trigger event to synchronize the mandatory inspiration with the patient's inspiratory effort. Similarly, detection of an expiratory signal within the cycle window initiates a cycle event to synchronize the mandatory expiration with the patient's expiration. This figure was made with a lung simulator (ASL 5000, IngMar Medical, Pittsburgh, Pennsylvania) connected to a ventilator (Avea, ViaSys/CareFusion, San Diego, California) set to deliver airway-pressure-release ventilation (pressure support = 0) with the Avea's “TI sync” and “TE sync” features activated.
- Fig. 3.
Our proposal for how set pressures should be defined for pressure-control ventilation modes on 3 of the ventilators mentioned in Table 1. PB = Puritan Bennett. PS = pressure support. PIP = peak inspiratory pressure. PEEP = positive end-expiratory pressure. IP = inspiratory pressure. Patm = atmospheric pressure.
- Fig. 4.
Idealized pressure, volume, and flow waveforms for pressure-control and volume-control ventilation, illustrating the use of our proposed conventions for the set and measured airway pressures. PS = pressure support. PIP = peak inspiratory pressure. IP = inspiratory pressure. PEEP = positive end-expiratory pressure. Patm = atmospheric pressure. Ppeak = peak airway pressure measured relative to atmospheric pressure (zero). Pplat = plateau pressure, or static pressure at the end of an inspiratory hold, measured relative to atmospheric pressure (zero).
- Fig. 5.
Examples of charting simulator output for representative ventilators in the bi-level ventilation mode mentioned in Figure 3. Top: Servo-i. Middle: Puritan Bennett 840. Bottom: LTV 950. IP = inspiratory pressure. PIP = peak inspiratory pressure. PEEP = positive end-expiratory pressure. PS = pressure support. Patm = atmospheric pressure. Ppeak = peak airway pressure measured relative to atmospheric pressure (zero).
