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.

HELLP! The Novel Use of Continuous Renal Replacement Therapy and Nitric Oxide in the Treatment of Acute Respiratory Failure in HELLP Syndrome

HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome is a rare but serious complication of pregnancy characterized by hemolytic anemia, elevated liver enzymes, and thrombocytopenia. It occurs in <1% of all pregnancies with 70% of cases developing before delivery, the majority occurring between the 27th and 37th weeks of gestation. Respiratory failure seen in HELLP syndrome clinically and radiographically appears similar to acute respiratory distress syndrome (ARDS), with presence of bilateral pulmonary opacities on imaging as well as persistent hypoxemia requiring elevated ventilator requirements. It is seen to complicate 3-10% of cases of HELLP syndrome. Pulmonary complications are theorized to occur as sequelae of the proinflammatory state induced by HELLP syndrome with endothelial dysfunction and subsequent microangiopathic hemolysis and thrombocytopenia. A robust cytokine inflammatory response similar to ARDS is seen, resulting in noncardiogenic pulmonary edema due to vasoplegia and capillary leak syndrome. We present a case of a 27-year-old uniparous female with a term pregnancy complicated by HELLP syndrome who developed respiratory failure requiring mechanical ventilation. Early CRRT and nitric oxide therapy were initiated, with the patient experiencing clinical and radiological improvement of respiratory function within 48 hours. We document the novel treatment of our patient’s acute respiratory failure with CRRT and nitric oxide and delve into the literature regarding its use in acute respiratory failure and ARDS in association with HELLP syndrome.

Nitric oxide as a therapeutic option for COVID-19 treatment: a concise perspective

Among several possible therapies applicable for treating COVID-19, nitric oxide therapy has also gained considerable interest. This article describes the same with mechanistic details.

Author Correction: Inhaled nitric oxide therapy in acute bronchiolitis: A multicenter randomized clinical trial

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Cost of nitric oxide therapy in neonates

A retrospective observational cohort study was performed to review the cost of inhaled nitric oxide (iNO) therapy in a UK neonatal intensive care setting over a 4-year period. 188 neonates with a median (IQR) gestational age and birth weight of 27 (24–37) weeks and 980 (695–2812) g, respectively, were treated with iNO. The median (IQR) duration of iNO therapy was 60 (22–129) hours. The mean cost of iNO therapy was approximately £820 per baby treated equivalent to £8.50 per hour of therapy. Alternative pricing models suggested a calculated cost of iNO therapy of between approximately £950 and £1350 per baby.