Background. Pulmonary arterial hypertension (PAH) is a known complication of unrepaired congenital heart disease (CH D) and is often the principal determinant of the clinical manifestations, course and feasibility of surgical treatment. Diagnostic work-up to determine feasibility of surgery includes invasive procedure like cardiac catheterization or lung biopsy. In our setting, we chose a simple and inexpensive diagnostic tool that would guide us in the management. To our knowledge, this is the first study with a prospective component that would determine the association of preoperative oxygen challenge test response to postoperative outcome in terms of in-hospital mortality and right ventricular dysfunction/failure among CHD patients with moderate to severe pulmonary hypertension.
Method. An ambispective cohort study was conducted among CHD patients with moderate to severe pulmonary hypertension who underwent surgical repair at PHC. Patients were followed-up from the time of operation until the time of discharge. Chart review was also conducted and enrolled patients who met the inclusion. Baseline characteristics and preoperative oxygen challenge test response were noted. Primary outcome is in-hospital mortality. Secondary outcome is right ventricular (RV) dysfunction/failure.
Results. There were 65 patients Included in the study. Mean age is at 52 ± 10.792. Most were females (69%), had atrial septal defect (ASD) (54%) and with moderate pulmonary hypertension (54%). The observed inhospital mortality rate was 6% and RV dysfunction is 12%. Room air S02 and S02 difference were associated with both postoperative in-hospital mortality and right ventricular dysfunction S02 difference (AUC of >0.6) has substantial ability to predict mortality. S02 difference of s 3.5 is the best-cut off to predict mortality with a sensitivity
50.0%, specificity of 54.1 %, PPV 6.7% and NPV 94.3%. S02 (room air), S02 (02 challenge) and S02 difference (AUC >0.5) were also considered in determining the cut-off for RV dysfunction, although less substantial.
Conclusion. Preoperative oxygen challenge test is of value in predicting postoperative outcome in moderate to severe pulmonary hypertension. Room air S02 and S02 difference was associated with both postoperative in- hospital mortality and right ventricular dysfunction. S02 difference of >3.5 is the best-cut off to predict mortality.