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Chapter 7
7-6 Respironics V200 Ventilator Operator’s Manual REF 1057983 A
Operating Theory
Patient Leak Display
Estimated patient leak (Pt Leak) is displayed in LPM and updated at each
breath. Pt Leak is the average leak rate during a breath (delivered volume
minus exhaled volume divided by the breath time).
Pt Leak is estimated breath by breath. If the physical characteristics of the
leak change, there will be a corresponding change in the actual leak flow,
which will be detected and leak estimation will be updated in subsequent
breaths. Physical characteristics of leaks are determined by a number of
factors, for example, the size and shape of the leak (such as a gap in the seal
between the mask and face). Leaks that may occur during invasive ventilation
are usually undesirable and are not compensated to allow easier leak
detection.
Ventilation Modes
Common to NPPV
Non-Invasive Positive Pressure Ventilation (NPPV)
In Non-Invasive Ventilation, gas is delivered to the patient via a nasal mask,
full face mask, nasal pillows, or mouthpiece with a lip seal. The operator
determines whether the mode is totally spontaneous (Spont Ventilation Mode)
or spontaneous with a backup rate (Spont/T Ventilation Mode).
Spontaneous Ventilation Mode (Spont)
In Spontaneous Ventilation Mode, the operator sets the pressure during
exhalation (EPAP) and the target pressure during inspiration (IPAP). The
patient triggers the breath based on the Flow Trigger setting. Exhalation is
determined by the setting E-Trigger, which is a percentage of peak flow during
the breath. Refer to Figure 7-7.
Spontaneous/Timed Ventilation Mode (Spont/T)
In the Spontaneous/Timed Ventilation Mode, the patient can breathe
spontaneously, or receive machined controlled breaths. The machine
controlled breaths are delivered for a set inspiratory time at a set breath rate.
In Spont/T mode, every patient initiated breath is spontaneous and restarts the
breath period timer. If the patient triggers a breath before the breath period
elapses, the ventilator delivers a spontaneous supported breath (based upon
the settings). If the breath period elapses without a patient trigger, the
ventilator delivers a ventilator initiated mandatory breath at the set IPAP level.
Patient initiated, time cycled breaths are not delivered in Spont/T mode. Refer
to Figure 7-7.