It may present as respiratory variations in the baseline tracing of pulse oximetry (with the height of oscillation correlating with the severity of pulsus and the degree of auto-PEEP [positive end-expiratory pressure]). Hence, pulse oximetry assessment of pulsus paradoxus can provide a useful noninvasive monitor of air trapping severity. Still, beware that positive pressure ventilation can reverse the respiratory changes in intrathoracic
pressure, so that the lowest systolic blood pressure will be recorded during expiration (reversed pulsus
paradoxus), rather than inspiration. Although the correlation between pulsus paradoxus and pulse oximetry recordings might not be influenced by the state of respiration (spontaneous or mechanical ventilation), reversed pulsus paradoxus is not a goodindicator of disease severity in patients receiving mechanical ventilation because the magnitude of the pulsus depends (at least in part) on the applied ventilatory pressures.
pressure, so that the lowest systolic blood pressure will be recorded during expiration (reversed pulsus
paradoxus), rather than inspiration. Although the correlation between pulsus paradoxus and pulse oximetry recordings might not be influenced by the state of respiration (spontaneous or mechanical ventilation), reversed pulsus paradoxus is not a goodindicator of disease severity in patients receiving mechanical ventilation because the magnitude of the pulsus depends (at least in part) on the applied ventilatory pressures.