Portal Bypass Complicated by Hepatopulmonary Syndrome

**Background:** Hepatopulmonary syndrome (HPS) is a known complication of liver disease and portal hypertension, characterized by intrapulmonary vasodilation and right-to-left shunting leading to hypoxemia. The condition is uncommon in the pediatric population. Potential mechanisms include increased production of vasoactive metabolites secondary to portal hypertension or decreased hepatic clearance due to liver disease or portal bypass. These metabolites cause pulmonary vasodilation and formation of intrapulmonary shunts. Diagnosis is confirmed by echocardiography with bubble study, which demonstrates delayed appearance of microbubbles in the left cardiac chambers (typically after 3–6 cardiac cycles), indicating intrapulmonary rather than intracardiac shunting. While transjugular intrahepatic portosystemic shunt (TIPS) may alleviate hypoxemia in some patients, liver transplantation remains the definitive curative treatment.

**Methods:** This is a single-patient case report. The patient initially presented at 8 years of age with cavernous transformation of the portal vein and variceal hemorrhage, for which a TIPS was successfully created. She returned at age 16 years after incidental discovery of TIPS occlusion on yearly surveillance ultrasound. Before induction of anesthesia for TIPS recanalization, she was noted to be hypoxemic to 85%. Physical examination revealed digital clubbing. Following successful TIPS recanalization and angioplasty, she underwent echocardiography with bubble study to confirm the diagnosis of HPS.

**Key Results:** The patient's oxygen saturation was 85% before anesthesia induction. Physical examination demonstrated digital clubbing. Echocardiography with bubble study confirmed the diagnosis of HPS by showing appearance of microbubbles within the left cardiac chambers at 7 cardiac cycles after systemic infusion, confirming intrapulmonary shunting. At 1-year follow-up, the TIPS remained patent by Doppler ultrasound. The patient remained asymptomatically hypoxemic in the low 90s at rest with desaturations to the mid 80s with activity. The authors note that on examination, patients with HPS desaturate further in the upright position (orthodeoxia) due to basilar predominance of shunts.

**Clinical Implications:** This case highlights that HPS can complicate portal hypertension and portal bypass in pediatric patients, even in the absence of intrinsic liver disease. HPS should be considered in the differential diagnosis of unexplained hypoxemia in children with portal hypertension or portosystemic shunts. Digital clubbing may be the first sign of HPS in the absence of pulse oximetry or blood gas assessment. While TIPS recanalization restored shunt patency, it did not reverse the hypoxemia, consistent with the understanding that liver transplantation remains the only curative treatment. The case underscores the importance of routine surveillance for TIPS patency and the need for clinical vigilance for HPS in at-risk pediatric populations.