PURPOSE: Acute chest syndrome (ACS) is a potentially fatal complication of sickle cell disease (SCD). Intravascular sickling and hemolysis produce pulmonary endothelial dysfunction characterized by reduced nitric oxide bioavailability. We describe our experience using inhaled nitric oxide (iNO) to treat ACS.
METHODS: We identified five patients over age 18 with ACS, who were treated with iNO in VCU's Medical ICU between June 2009 and March 2010. ACS was defined as fever >38.5 C, chest pain, new chest radiographic infiltrate, and respiratory symptoms in a patient with SCD.
RESULTS: Patients' median age was 29 years (18-43). No patient had pre-existing pulmonary hypertension. All received antibiotics and exchange transfusion. Two patients required mechanical ventilation and vasopressors. Inhaled NO was started at 20 ppm via nasal cannula or ventilator circuit. Median duration of therapy was 99 hours. Prior to starting iNO, transthoracic echocardiogram (TTE) in four patients revealed moderate to severe right ventricular (RV) dilation and mildly to severely reduced RV function. Within 24 hours of initiating iNO, vasopressor requirements diminished or disappeared, and median P/F ratio improved from 165 to 297. Within 48 hours, TTE showed improved RV size and function. Median pulmonary artery systolic pressure improved from 64 mmHg (40 -72) to 45 mmHg (37-48). Median tricuspid annular plane systolic excursion improved from 1.5 cm (1.2-1.6) to 2 cm (1.9-2.1). Follow-up TTE in two patients confirmed normal RV size and function with trivial tricuspid regurgitation. All patients survived to discharge.
CONCLUSION: This is the first description of using iNO in adults with ACS to rapidly improve RV function and hypoxemia. Large, prospective trials are needed to evaluate these and other endpoints.
CLINICAL IMPLICATIONS: NO plays many roles in promoting vascular homeostasis. Our observed effect of iNO in ACS may reflect improved endothelial function related to iNO's capacity to dilate ventilated capillary beds, reduce RV after-load and improve V/Q matching. If iNO indeed improves outcomes in ACS, it may also affect the chronic vasculopathy and pulmonary hypertension of SCD.
DISCLOSURE: Alice Herlihy, No Financial Disclosure Information; No Product/Research Disclosure Information