Non-invasive assessment of intrapulmonary shunt and ventilation to perfusion ratio in children with hepatopulmonary syndrome before and after liver transplantation

HEPATOPULMONARY SYNDROME IN PEDIATRIC PATIENTS WITH PORTAL HYPERTENSION - AN INTEGRATIVE REVIEW

BACKGROUND

Hepatopulmonary syndrome (HPS) is characterized by the triad of abnormal arterial oxygenation caused by intrapulmonary vascular dilatations (IPVD) in the setting of advanced liver disease or portal hypertension, impacting the patient's quality of life and survival. There are still many gaps in the literature on this topic, especially in pediatrics, with practices frequently based on extrapolation of data obtained from adults.

OBJECTIVE

Provide a synthesis of the current knowledge about HPS in children.

METHODS

The research was carried out through narrative review. The databases used for the search include Medline, Embase, Elsevier, Lilacs and Scielo. The keywords used were "hepatopulmonary syndrome" AND child, children, infant, preschool, pediatric.

RESULTS

In cirrhotic children, the prevalence of HPS can reach up to 42.5%, and it is even more common in those whose underlying condition is biliary atresia, reaching up to 63%. Screening with pulse oximetry (O2 saturation <96%), unlike in adults, has low sensitivity in the pediatric age group. Management involves supportive care with oxygen therapy; liver transplantation is the only definitive treatment to reverse the condition and HPS is considered an exceptional criterion for waitlist. The waitlist mortality is similar among children listed by HPS as a special criterion when compared to those listed for other reasons. The reported rates of complete resolution of hypo-xemia after liver transplantation are close to 100% in children. The post-liver transplantation survival is similar or slightly lower in children with HPS when compared to those without HPS. Contrary to findings from adults, no differences were found in post- liver transplantation mortality between children of different hypoxemia ranges, although longer mechanical ventilation time and hospital stay were observed in children with PaO2 <50 mmHg.

CONCLUSION

HPS is not an uncommon complication of cirrhosis in children and adolescents, particularly when biliary atresia is the underlying condition. There are still many gaps to be filled regarding the condition, and this article demonstrates that not all data obtained in studies with adults reflects the disease's behavior in pediatrics, especially concerning prognosis.

Respiratory problems associated with liver disease in children

Respiratory manifestations of chronic liver disease have a profound impact on patient clinical outcomes. Certain conditions within paediatric liver disease have an associated respiratory pathology. This overlap between liver and respiratory manifestations can result in complex challenges when managing patients and requires clinicians to be able to recognise when referral to specialists is required. While liver transplantation is at the centre of treatment, it opens up further potential for respiratory complications. It is established that these complications place patients at risk of longer stays in hospital and reduced survival. Additionally, late post-transplant complications can occur, including post-transplant lymphoproliferative disease and immunosuppression-induced interstitial lung disease. Although rare, it is important for clinicians to recognise these conditions to allow for prompt management. Finally, as liver disease progresses in children, respiratory complications can occur. Hepatopulmonary syndrome can occur in the context of portal hypertension, resulting in increased mortality and poorer quality of life for patients. Another consequence is portopulmonary hypertension, which can be associated with poor survival. Failure to recognise these complications in children may result in poorer outcomes and therefore it is vital that clinicians can establish when referral to a paediatric respiratory medicine specialist is required.

Ventilation-to-perfusion relationships and right-to-left shunt during neonatal intensive care in infants with congenital diaphragmatic hernia

BACKGROUND

We aimed to explore the postnatal evolution of ventilation/perfusion ratio (VA/Q) and right-to-left shunt in infants with congenital diaphragmatic hernia (CDH) and whether these indices predicted survival to discharge.

METHODS

Retrospective cohort study at King's College Hospital, London, UK of infants admitted with CDH in 10 years (2011-2021). The non-invasive method of the oxyhaemoglobin dissociation curve was used to determine the VA/Q and shunt in the first 24 h of life, pre-operation, pre-extubation and in the deceased infants, before death.

RESULTS

Eighty-two infants with CDH (71 left-sided) were included with a median (IQR) gestation of 38.1(34.8-39.0) weeks. Fifty-three (65%) survived to discharge from neonatal care. The median (IQR) VA/Q in the first 24 h was lower in the deceased infants [0.09(0.07-0.12)] compared to the ones who survived [0.28(0.19-0.38), p < 0.001]. In the infants who survived, the VA/Q was lower in the first 24 h [0.28 (0.19-0.38)] compared to pre-operation [0.41 (0.3-0.49), p < 0.001] and lower pre-operation compared to pre-extubation [0.48 (0.39-0.55), p = 0.027]. The shunt was not different in infants who survived compared to the infants who did not.

CONCLUSIONS

Ventilation-to-perfusion ratio was lower in infants who died in the neonatal period compared to the ones that survived and improved in surviving infants over the immediate postnatal period.

IMPACT

The non-invasive method of the oxyhaemoglobin dissociation curve was used to determine the ventilation/perfusion ratio VA/Q in infants with congenital diaphragmatic hernia (CDH) in the first 24 h of life, pre-operation, pre-extubation and in the deceased infants, before death. The VA/Q in the first 24 h of life was lower in the infants who did not survive to discharge from neonatal care compared to the ones who survived. In the infants who survived, the VA/Q improved over the immediate postnatal period. The non-invasive calculation of VA/Q can provide valuable information relating to survival to discharge.

Improved survival in children with HPS: Experience from two high volume liver transplant centers across continents

BACKGROUND

Severe HPS increases morbidity and mortality after LT in children. We reviewed the combined experience of LT for HPS in children from two LT centers in Europe and Asia.

METHODS

All children with "proven" HPS as per ERS Task Force criteria (detailed in manuscript) who underwent LT were categorized into M (PaO₂ ≥80 mmHg), Mo (PaO₂  = 60-79 mmHg), S (50-59 mmHg), and VS (PaO₂ <50 mmHg) HPS, based on room air PaO₂ .

RESULTS

Twenty-four children with HPS underwent 25 LT (one re-transplantation) at a median age of 8 years (IQR, 5-12), after a median duration of 8 (4-12) months following HPS diagnosis. Mechanical ventilation was required for a median of 3 (1.5-27) days after LT. Ten children had "S" post-operative hypoxemia, requiring iNO for a median of 5 (6-27) days. "VS" category patients had significantly prolonged invasive ventilation (median 35 vs. 3 and 1.5 days; p = .008), ICU stay (median 39 vs. 8 and 8 days; p = .007), and hospital stay (64 vs. 26.5 and 23 days; p < .001) when compared to "S" and "M/Mo" groups, respectively. The need for pre-transplant home oxygen therapy was the only factor predicting need for re-intubation. Patient and graft survival at 32 (17-98) months were 100% and 95.8%. All children ultimately had complete resolution of HPS.

CONCLUSIONS

VS HPS is associated with longer duration of mechanical ventilation and hospital stay, which emphasizes the need for early LT in these children.