A patient with the hepatopulmonary syndrome may develop an intrapulmonary right to left shunt. The presence and size of the shunt can be estimated by pulse oximetry.
Patient selection: hepatopulmonary syndrome
Testing: pulse oximetry (similar findings can be seen with PaO2 but pulse oximetry is more convenient and less painful).
Pathological test for intrapulmonary shunt:
(1) oxygen saturation by pulse oximetry in percent while supine <= 92%
(2) (oxygen saturation in percent while supine) - (oxygen saturation in percent while upright) > 4%
Analysis of Figure 2 in Deibert et al over range 65 to 93% SpO2:
percent of intrapulmonary shunt =
= (-1.498 * (oxygen saturation in percent)) + 139.5
Hoerning et al note that a pediatric patient can have the hepatopulmonary syndrome without hypoxemia if a shunt has not developed.
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