Addition of Nitric Oxide to Oxygen Improves Cardiopulmonary Function in Patients With Severe COPD: Materials and Methods
However, previous studies in COPD patients have suggested that although pulmonary vascular resistance is consistently decreased by NO inhalation, V/Q matching is unaffected or even worsened. It has been suggested that NO may reverse hypoxic pulmonary vasoconstriction in those patients in whom this mechanism preserves V/Q matching. In these studies, the results of NO inhalation were generally compared with the effect of breathing room air or 100% oxygen.
We therefore designed a prospective, dose-ranging study to test the hypothesis that inhaled NO would lead to an improvement of pulmonary hemodynamics and oxygenation when added to LTOT in patients with COPD.
Materials and Methods
All patients gave written informed consent to the study protocol that was approved by the institutional review board. Eighteen patients (12 male and 6 female) with a mean age of 57 years (range, 41 to 75 years) were studied (Table 1). All had evidence of COPD, as defined by the American Thoracic Society, in the absence of acute respiratory failure. Patients breathed spontaneously and were receiving LTOT given for >15 h/d. At the time of the investigation, all patients studied had been receiving LTOT for >12 months, and were in stable condition for at least 6 weeks. The prescription of LTOT was made in accordance with the recommendations of the Austrian Society for Pneumology, namely, that Pa02 at rest and in room air has to be <59 mm Hg in three independent measurements in the absence of signs of acute infection. Lung function data obtained prior to the investigation are documented in Table 1. canadianfamilypharmacy
At the commencement of the study, patients were admitted to an ICU where they remained in a quiet single room. During the period of observation, no signs of severe stress were revealed by changes in BP, heart rate (HR) (Table 2), or respiratory rate. Under local anesthesia, a pulmonary^ artery catheter (Ref-Sat; Baxter; Irvine, Calif) was inserted via the internal jugular vein and guided into a pulmonary artery under ECG monitoring. The position was verified by chest radiography. A polyethylene catheter (Viggo; Spectramed; Helsingborg, Sweden) was introduced into the radial arteiy, and a cannula was inserted into a peripheral arm vein. The patients were studied in a semirecumbent position, and the pressure transducers were raised to the level of the right atrium.
Table 1—Demographic Data and Lung Function Tests
|Mean±SEM 57±9||p 1 + Oo||56 ±14||37 ±15||42 ±14|
Table 2—Hemodynamic Variables
|HR, beats/min||88 ±13||89±11||86 ±14||87±12||87±13|
|PCWP, mm Hg||9±4||10±4||8±3||8±3||8±3|
|MAP, mm Hg||91±12||92±11||93 ±12||95±11||96 ±14|
|SVRI, dyne • s • cm • m~2||2,296 ±850||2,390 ±776||2,309 ±749||2,414 ±943||2,211±787|
|MPAP, mm Hg||31±7||29±7||25±5f||24±6f||24±5f|
|PVRI, dyne • s • cm • m~2||586 ±342||565 ±321||459±259f||419±237f||392±215f|