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Monitors and definitions (continued)
Mechanics (continued)
P
PEEP
tp
MIP
P
100
WOB
V
WOB
P
WOB
I
Capnography
EtCO
2
VCO
2
VtCO
2
Vd ana
Vd/Vt ana
Vd phy
Vd/Vt phy
Vd alv
The difference between the corresponding airway and esophageal
pressures at the end of the expiratory hold during
an AutoPEEP maneuver. Requires an inspiratory hold and
esophageal catheter.
The maximum negative airway pressure that is achieved by the
patient, during an expiratory hold maneuver.
The negative pressure that occurs 100 ms after an inspiratory
effort has been detected.
Ventilator work of breathing (WOB
of airway pressure (PAW) minus the baseline airway pressure
(PEEPAW) times the change in tidal volume to the patient (-V)
during inspiration, and normalized to the total inspiratory tidal
volume (Vti).
Patient work of breathing (WOB
inspiratory tidal volume. Patient work of breathing is defined as
the summation of two work components: Work of the lung and
work of the chest wall. Requires an esophageal balloon.
Imposed work of breathing (WOBI) is defined as the work
performed by the patient to breathe spontaneously through the
breathing apparatus, (i.e., the E.T. tube), the breathing circuit and
the demand flow system. Requires a tracheal catheter.
Note: Monitored values are displayed as BTPS.
The patient's peak expired CO
CO
sensor in the airway, calculated for each breath then averaged
2
as specified by set EtCO
Minute volume of exhaled CO
averaged over a user-selectable time. Requires flow measurement
at the wye or circuit compliance active.
Tidal volume of exhaled CO
averaged over the set VCO
surement at the wye or circuit compliance active.
The volume of dead space in the patient's conducting airways
from the nose to the level of the terminal bronchioles measured
for each breath, then averaged over the set CO
Also includes any mechanical dead spaces added to the ventila-
tor circuit between the CO
measurement at the wye or circuit compliance active.
Anatomic Vd/Vt is averaged over the set VCO
time. Requires flow measurement at the wye or circuit
compliance active.
Comprises Vd ana as well as the volume of the respiratory zone
(respiratory bronchioles, alveolar ducts and alveoli) not participat-
ing in gas exchange. Requires an arterial blood gas sample.
Physiologic Vd/Vt is averaged over the set VCO
Requires an arterial blood gas sample.
Alveolar dead space is the difference between physiological
dead space and anatomical dead space. It represents the volume
of the respiratory zone that is from ventilation of relative
under-perfused or non-perfused alveoli. Requires an arterial
blood gas sample.
) is defined as the summation
V
), normalized to the total
P
as measured and reported by the
2
averaging time.
2
measured continuously and
2
, measured for each breath and then
2
averaging time. Requires flow mea-
2
sensor and the patient. Requires flow
2
averaging time.
2
averaging
2
averaging time.
2
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