Dead space ratio as a tool in nitric oxide weaning: a study in pulmonary hypertensive disease

Objectives: To describe the association between successful weaning of inhaled nitric oxide and trends in dead space ratio during such weans in patients empirically initiated on nitric oxide therapy out of concern of pulmonary hypertensive crisis. Patients: Children in a cardiac intensive care unit initiated on inhaled nitric oxide out of clinical concern for pulmonary hypertensive crisis retrospectively over 2 years. Measurements and Main Results: Twenty-seven patients were included, and nitric oxide was successfully discontinued in 23/27. These patients exhibited decreases in dead space ratio (0.18 versus 0.11, p = 0.047) during nitric oxide weaning, and with no changes in dead space ratio between pre- and post-nitric oxide initiation (p = 0.88) and discontinuation (p = 0.63) phases. These successful patients had a median age of 10 months [4.0, 57.0] and had a pre-existent diagnosis of CHD in 6/23 and pulmonary hypertension in 2/23. Those who failed nitric oxide discontinuation trended with a higher dead space ratio at presentation (0.24 versus 0.10), were more likely to carry a prior diagnosis of pulmonary hypertension (50% versus 8.7%), and had longer mechanical ventilation days (5 versus 12). Conclusions: Patients empirically placed on nitric oxide out of concern of pulmonary hypertensive crisis and successfully weaned off showed unchanged or decreased dead space ratio throughout the initiation to discontinuation phases of nitric oxide therapy. Trends in dead space ratio may aid in determining true need for nitric oxide and facilitate effective weaning. Further studies are needed to directly compare trends between success and failure groups.

Peripartum outcomes in a large population of women with pulmonary arterial hypertension associated with congenital heart disease

Aims Pulmonary arterial hypertension is a severe complication in patients with congenital heart disease and poses a significant risk to women wishing to become pregnant. This study describes the clinical presentation, maternal outcomes and risk factors for the peripartum period in women with pulmonary arterial hypertension related to congenital heart disease (PAH-CHD). Methods All pregnant women with PAH-CHD who were admitted for delivery in a tertiary center between February 2011–September 2016 were included. Logistic regression analysis was used to identify predictors of the combined endpoint of maternal death, severe heart failure requiring treatment, or pulmonary hypertensive crisis. Results Ninety-three women (94 pregnancies) were included. Average age was 27.5 ± 4.4 years. Thirty (31.9%) patients had Eisenmenger syndrome, 51 (54.3%) had pulmonary arterial hypertension associated with systemic-to-pulmonary shunts, and 13 (13.8%) had pulmonary arterial hypertension with corrected congenital heart disease. Twenty-three (24.5%) women required admission for delivery within two days from presentation. Elective Cesarean section was performed in 95.7% of women, with intravertebral anesthesia in 93.6%. Fifty-one (54.2%) patients received pulmonary arterial hypertension therapies during pregnancy. Six (6.4%) women died, 33 (35.1%) developed heart failure and 10 (10.6%) had a pulmonary hypertensive crisis. Patients who met the combined endpoint ( n = 34, 36.2%) were more likely to have Eisenmenger syndrome or repaired defects ( p < 0.001). Other risk factors in the multivariate model included lower arterial blood oxygen saturation, higher brain natriuretic peptide, and pericardial effusion on echocardiography. Conclusion Maternal mortality and morbidity remain high in PAH-CHD patients, who should be counseled on the risks of pregnancy and managed in a tertiary multidisciplinary environment to improve prognosis.