Addition of Nitric Oxide to Oxygen Improves Cardiopulmonary Function in Patients With Severe COPD: Hemodynamic
All patients were observed on-line with ECG, invasive BP monitoring, and measurement of peripheral oxygen saturation (Hewlett Packard; Boblingen, Germany). Cardiac index (Cl) was calculated using the thermodilution technique and expressed as the mean of the values recorded from four 10-mL injections of iced saline solution at 1 to 5°C. my canadian pharmacy online
The following hemodynamic and oxygenation variables were measured and derived: HR in beats/min, mean arterial pressure (MAP) in mm Hg, cardiac Cl in L/min/m2, right ventricular ejection fraction (REF) in %, systemic vascular resistance index (SVRI) in dyne • s * cm • m, MPAP in mm Hg, pulmonary vascular resistance index (PVRI) in dyne • s • cm • m~2, and pulmonary venous admixture (Qs/Qt) in %. All hemodynamic and oxygenation calculations were performed with a cardiac output computer (Explorer; Baxter) and a pressure monitoring kit (Baxter) according to standard formulas. Blood gas samples were analyzed immediately after withdrawal (995-Hb; AVL; Graz, Austria). NO was added via a device for NO delivery (Pulmonox; Messer Griesheim; Gumpoldskirchen, Austria) and continuous analysis of NO and oxidation products of NO (NOx) concentrations using a chemiluminescense detection analyzer (ECO Physics; Diirnten, Switzerland). When NO binds to hemoglobin, it forms nitrosylhemoglobin, which is oxidized to methemoglobin. To evaluate the potential development of methemoglobinemia, we measured methemoglobin in every blood gas sample by spectrophotometry (AVL 912; AVL).
The baseline measurements and calculations of oxygenation and hemodynamic variables were made under stable LTOT conditions. Additional measurements were taken after application of a face-mask system (Draeger; Vienna, Austria) that provided free gas flow and allowed accurate titration of inspired oxygen fraction (FIo2) as well as delivery and sampling of NO. By titrating the FIo2, blood gases were adjusted to match LTOT conditions (control, C). Then, 5, 10, and 20 ppm NO were added to the oxygen/air gas mixture. One hour of accommodation was allowed at each level before measurements were taken. FIo2 was kept constant with the aid of an oxygen analyzer (Oxydig; Draeger; Lubeck, Germany) interconnected directly before the face mask of the patient.
Data are given as mean±SEM. Statistical analysis was performed by determination of the variance for three repeated measurements using the Huynh-Feldt correction. All p values are based on two-sided tests; p<0.05 was considered significant.