Distribution of inhaled nitric oxide during sequential and continuous administration into the inspiratory limb of the ventilator

Abstract

CTA did not provide homogenous mixing of NO with the tidal volume and resulted in fluctuating INSP-NOMeas. In contrast, SQA delivered stable and predictable NO concentrations during controlled mechanical ventilation with a constant inspiratory flow and was economical compared to CTA. However, SQA did not provide stable and predictable NO concentrations during pressure support ventilation.

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“…It is possible to demonstrate this phenomenon in a lung model by using a long inspiratory limb and sampling the gas from sites corresponding to different multiples of tidal volume [10]. As shown in Fig 2, concentrations of NO measured from sampling sites corresponding to one and two tidal volumes are higher than those measured from sampling sites corresponding to half and one and a half tidal volumes, respectively.…”

“…These two systems are not comparable in their performance since only sequential administration coupled with controlled mechanical ventilation assures stable inspired NO concentrations [3,10]. Continuous administration, though simple and inexpensive, does not allow homogeneous mixing of NO with the inspired gas [10].…”

“…Continuous administration, though simple and inexpensive, does not allow homogeneous mixing of NO with the inspired gas [10]. These differences have been well evidenced by Imanaka et al using a test lung model [3].…”

“…There is no detectable bolus at the site corresponding to 2 tidal volumes, suggesting an early homogenization of the inspired gas. Published with permission [10]. …”

“…The time delay of the apparatus was 2.4 s. Accordingly, the beginning of inspiration and expiration (represented by arrows) is shifted 2.4 s to the right compared to the respiratory flow recording. Published with permission [10]. …”