Mechanics (continued)
Cstat
Cstat/kg
Respiratory system compliance (C
RS
), (a.k.a. static compliance
Cstat), absolute and normalized to patient weight.
Note:
This requires an Inspiratory Hold maneuver.
PIFR
Peak inspiratory flow rate.
PEFR
Peak expiratory flow rate.
Ccw
The ratio of the tidal volume (exhaled) to the delta esophageal
Pressure (dP
ES
). Requires an esophageal balloon.
CLUNG
The ratio of the tidal volume (exhaled) to the delta
transpulmonary pressure. The delta transpulmonary pressure
is the difference between the airway plateau pressure (during
an inspiratory pause) and esophageal pressure (at the time
the airway plateau pressure is measured) minus the difference
between the airway and esophageal baseline pressures. Requires
an inspiratory hold and esophageal balloon.
C
20
/ C
The ratio of the dynamic compliance during the last 20% of
inspiration (C
20
) to the total dynamic compliance (C).
R
RS
The total resistance during the inspiratory phase of a breath.
Respiratory system resistance is the ratio of the airway pressure
differential (peak–plateau) to the inspiratory flow 12 ms prior to
the end of inspiration. Requires an inspiratory hold.
R
PEAK
The peak expiratory resistance (R
PEAK
) is defined as the resistance
at the time of the peak expiratory flow (PEFR).
R
IMP
The airway resistance between the wye of the patient circuit
and the tracheal sensor. Requires an inspiratory hold and
tracheal catheter.
R
LUNG
The ratio of the tracheal pressure differential (peak–plateau) to
the inspiratory flow 12 ms prior to the end of inspiration. Requires
an inspiratory hold and tracheal catheter.
dP
AW
The difference between peak airway pressure (P
PEAK AW
) and base-
line airway pressure (PEEP
AW
).
dP
ES
The difference between peak esophageal pressure (PPEAK
ES
) and
baseline esophageal pressure (PEEP
ES
).
AutoPEEP
The airway pressure at the end of an expiratory hold maneuver.
Requires a passive patient.
dAutoPEEP
The difference between airway pressure at the end of an
expiratory hold maneuver and the airway pressure at the start of
the next scheduled breath after the expiratory hold maneuver.
Requires a passive patient.
AutoPEEP
ES
The difference between esophageal pressure measured at the end
of exhalation (PEEP
ES
) minus the esophageal pressure measured at
the start of a patient-initiated breath (P
ES start
) and the sensitivity of
the ventilator’s demand system. The sensitivity of the ventilator’s
demand system is the difference between the baseline airway
pressure (PEEP
AW
) and the airway pressure when the patient
initiates a breath (PAW start). Requires an esophageal balloon.
P
tp
Plat
Transpulmonary pressure during an inspiratory hold, which is the
difference between the airway plateau pressure (P
PLAT AW
) and the
corresponding esophageal pressure. Requires an inspiratory hold
and esophageal balloon.
Monitors and definitions (continued)
