Dedicated nitric oxide equipped ventilators are now available commercially
but are not yet common in clinical practice. With other ventilators, there
is no standardized procedure for the administration or monitoring of nitric
oxide. We describe the use of nitric oxide in conjunction with a simple ti
me-cycled, pressure regulated, flow generating ventilator attached to a mod
el infant-sized lung. The measured nitric oxide concentrations were always
less than calculated. Infusion site, minute ventilation and sampling port a
ll affected nitric oxide concentration (P < 0.05). Increasing minute ventil
ation lowered measured nitric oxide concentration exponentially. Mixing of
gases improved when nitric oxide was infused closer to the ventilator. Acid
contamination was found in water samples from humidifier, water trap and v
entilator gas outlet. Acidification was reduced, without change in measured
nitric oxide delivery, when infused prehumidifier. We recommend, when used
as therapy, nitric oxide levels in inspired gases should always be measure
d.