Nitric oxide (NO) concentrations measured in a lung model with different systems of administration during volume-control and pressure-control ventilation. The NO concentration is measured at simulated midtrachea during (a) volume-control and (b) pressure-control ventilation. The target NO concentration was 20 ppm. Thick and thin lines represent NO concentration measured using a fast and slow-response analyser, respectively. The model simulates 100% NO uptake. Different modes of administration were tested: pre = administration before the ventilator; ii = sequential administration into the inspiratory limb; iy = sequential administration into the Y-piece; ci = continuous administration into the inspiratory limb; cy = continuous administration into the Y piece. Published with permission .