REDUCTION IN NITROGEN-DIOXIDE CONCENTRATION BY SODA LIME PREPARATIONSDURING SIMULATED NITRIC-OXIDE INHALATION

Nitrogen dioxide is formed during delivery of inhaled nitric oxide for the treatment of patients with pulmonary hypertension. Soda lime has been shown to absorb nitrogen dioxide. We tested three different comme rcially available soda lime preparations (Sodasorb, Dragersorb 800 and Sofnolime) for their efficacy in absorbing nitrogen dioxide and nitri c oxide during simulated nitric oxide inhalation. All soda lime prepar ations absorbed nitrogen dioxide (15%, 24% and 34%, respectively). To test if this difference could be attributed to the potassium hydroxide (KOH) content of the different preparations, two other preparations w ith a higher (3.0% and 7.3%w/w, respectively) KOH content were tested and we found an increase in nitrogen dioxide removal up to 47% and 46% , respectively. We conclude that soda lime absorbed nitrogen dioxide d uring nitric oxide inhalation. This effect seemed to be moderate under simulated clinical conditions, but increased using soda lime with a h igher KOH content. Nevertheless, we recommend continuous monitoring of inspired nitrogen dioxide concentration during clinical inhalation of nitric oxide.