ECMO-/ECLS

Therefore, whether the patient is spontaneously breathing or mechanically
ventilated, measurements should be obtained at the end of inspiration when
intrathoracic pressure is at baseline. Notably, two additional issues should be
considered. First, positive intrathoracic pressures may artificially elevate
recorded intravascular pressures. This can only be discerned through placement
of an esophageal pressure monitor. Second, continuous pressure ventilators
(oscillator, jet) do not have an expiratory phase. Again, intravascular pressure
measurements may be artificially elevated and consideration should be given to
placing an esophageal pressure probe to determine the contribution of
intrathoracic pressure to values obtained.
Normal central venous pressure varies between 0-5 cm H 2 O. However,
certain pre-existing disease states such as pulmonary hypertension, right
ventricular failure, tricuspid valvular disease, and others may result in elevated
values and/or abnormal waveforms. In addition, acute disease states may
require higher central venous pressures to facilitate cardiac output.
Central venous oxygen saturation monitoring (ScvO 2 ) is utilized as a
marker of oxygen extraction when compared to arterial saturation. It does not
include return from the coronary sinus and as such is often elevated as
compared to true mixed venous oxygen saturation (SvO 2 ) as measured from the
pulmonary artery. ScvO 2 should be measured from the SVC, as IVC
measurements are highly variable with changes in mesenteric circulation and do
not correlate with true SvO 2. ScvO 2 has been utilized to guide early goal-directed
therapy for adult sepsis with good outcomes. Normal SvO 2 is 65-75%, with lower