During neonatal mechanical ventilatory support, the delivered nitric oxide concentration is affected by the ventilatory setting.
OBJECTIVE
To assess whether the delivered nitric oxide (NO) concentration is affected by a change in the ventilatory setting during neonatal mechanical ventilatory support.


METHODS
Prospective, experimental study.


METHODS
Laboratory at Nagoya City University Medical School.


METHODS
This study was performed by using a pressure-limited, time-cycled, ventilatory support with a neonatal circuit and a 50-mL silicone test lung. NO in N2 gas was administrated into the inspiratory limb at a distance of 4 cm, 80 cm, or 160 cm from the Y piece connected to the adapter of an endotracheal tube. The NO concentration was measured every 0.5 sec by a chemiluminescence analyzer at the Y piece.


RESULTS
NO concentrations were compared with each of the ventilatory settings of peak inspiratory pressure (PIP) (10-30 cm H2O), positive end-expiratory pressure (0-10 cm H2O), ventilatory flow (10, 20, 30 L/min), and ventilatory rate (30, 40, 50, 60, 70 breaths/min), respectively. The NO concentration was significantly lower when NO was added at 4 cm than at 80 cm or 160 cm from Y piece at the same ventilatory setting of PIP, positive end-expiratory pressure and ventilatory flow, respectively, (p < .01). Although the NO concentration was increased as the settled PIP level was increased (p < .01 or p < .05), it was not changed when the settled positive end-expiratory pressure level was increased. A decrease was seen in the NO concentration as the settled ventilatory flow was increased (p < .01). Lastly, the NO concentration fluctuated greatly in association with the settled ventilatory rate.


CONCLUSIONS
The NO concentration delivered to patients is influenced by the ventilatory setting during neonatal mechanical ventilatory support.
Yamaguchi
N
N
Department of Pediatrics, Nagoya City University Medical School, Nagoya, Japan. yamaguti@med.nagoya-cu.ac.jp
Togari
H
H
Suzuki
S
S
D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007442:Intubation, Intratracheal; D008176:Lung Volume Measurements; D008297:Male; D009569:Nitric Oxide / Q000008:administration & dosage / Q000502:physiology*; D010547:Persistent Fetal Circulation Syndrome / Q000503:physiopathology / Q000628:therapy; D011446:Prospective Studies; D012121:Respiration, Artificial; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology* / Q000628:therapy
D009569:Nitric Oxide