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Pulmonary uptake and modes of administration of inhaled nitric oxide in mechanically-ventilated patients.

Puybasset L, Rouby JJ - Crit Care (1998)

View Article: PubMed Central - HTML - PubMed

Affiliation: Surgical Intensive Care Unit, Department of Anesthesiology, La Pitié-Salpêtrière Hospital, 47-89, Boulevard de I'Hôpital, 75013 Paris, France. louis.puybasset@psl.ap-hop-paris.fr

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Inhaled nitric oxide (NO) is a selective pulmonary vasodilator which reduces pulmonary artery pressure and increases arterial oxygenation in patients with adult respiratory distress syndrome (ARDS)... Despite these beneficial effects, inhaled NO has not yet been shown to improve outcome... During artificial ventilation, it can be administered in the downstream of the ventilator into the inspiratory limb of the ventilatory circuit, or can be mixed with oxygen and nitrogen in the upstream part of the system... There is no risk of overdose due to momentary interruption of ventilation during tracheal suctioning or acute reduction of minute ventilation when the ventilator is in partial-support mode... Similarly, an accidental interruption of the power supply to the ventilator does not result in an overdose after the restoration of power... It is necessary to evaluate each system before its clinical usage and to monitor the actual concentrations of NO delivered after the absorber... Another potential problem is that the passage of NO through a humidification chamber results in the dissolution of the gas in water with the formation of nitric acid (a phenomenon that does not occur with heat moisture exchangers) and in a decrease in the NO concentration actually delivered to the patient... The magnitude of the bolus effect is also inversely related to the NO concentration in the cylinder... Changing from a 22.5 ppm cylinder to a 900 ppm cylinder results in a 50-fold reduction in the volume of the bolus... Continuous monitoring of the fluctuation of tracheal NO concentrations in a given patient could thus be a reliable 'marker' of pulmonary function during the course of ARDS... A display of tracheal NO concentration on the monitor screen is available on the latest chemiluminescence apparatus (EVA 4000, Sérès, Aix-en-Provence, France) giving the possibility of continuously monitoring the fluctuations in tracheal NO concentration as an index of 'pulmonary function' during the course of ARDS... In 1998, inhaled NO should be administered in such a way that stable and predictable concentrations in the inspiratory limb are obtained... It can, therefore, be considered as an index of ventilatory perfusion ratio mismatch, and can be continuously monitored in ARDS... In contrast, the continuous delivery of NO in the inspiratory limb leads to unpredictable and fluctuating concentrations of NO and must be considered as an unsafe mode of administration, unless fast-response chemiluminescence apparatus is used for monitoring.

No MeSH data available.


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 [3].
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Figure 1: 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 [3].

Mentions: 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]. These differences have been well evidenced by Imanaka et al using a test lung model [3]. As illustrated by Fig 1, these authors recorded a peak NO concentration which was 10 times greater than the target concentration when using continuous administration during volume-controlled ventilation. In contrast, using sequential administration, inspired NO was always similar to the target concentration.


Pulmonary uptake and modes of administration of inhaled nitric oxide in mechanically-ventilated patients.

Puybasset L, Rouby JJ - Crit Care (1998)

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 [3].
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC137224&req=5

Figure 1: 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 [3].
Mentions: 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]. These differences have been well evidenced by Imanaka et al using a test lung model [3]. As illustrated by Fig 1, these authors recorded a peak NO concentration which was 10 times greater than the target concentration when using continuous administration during volume-controlled ventilation. In contrast, using sequential administration, inspired NO was always similar to the target concentration.

View Article: PubMed Central - HTML - PubMed

Affiliation: Surgical Intensive Care Unit, Department of Anesthesiology, La Pitié-Salpêtrière Hospital, 47-89, Boulevard de I'Hôpital, 75013 Paris, France. louis.puybasset@psl.ap-hop-paris.fr

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

Inhaled nitric oxide (NO) is a selective pulmonary vasodilator which reduces pulmonary artery pressure and increases arterial oxygenation in patients with adult respiratory distress syndrome (ARDS)... Despite these beneficial effects, inhaled NO has not yet been shown to improve outcome... During artificial ventilation, it can be administered in the downstream of the ventilator into the inspiratory limb of the ventilatory circuit, or can be mixed with oxygen and nitrogen in the upstream part of the system... There is no risk of overdose due to momentary interruption of ventilation during tracheal suctioning or acute reduction of minute ventilation when the ventilator is in partial-support mode... Similarly, an accidental interruption of the power supply to the ventilator does not result in an overdose after the restoration of power... It is necessary to evaluate each system before its clinical usage and to monitor the actual concentrations of NO delivered after the absorber... Another potential problem is that the passage of NO through a humidification chamber results in the dissolution of the gas in water with the formation of nitric acid (a phenomenon that does not occur with heat moisture exchangers) and in a decrease in the NO concentration actually delivered to the patient... The magnitude of the bolus effect is also inversely related to the NO concentration in the cylinder... Changing from a 22.5 ppm cylinder to a 900 ppm cylinder results in a 50-fold reduction in the volume of the bolus... Continuous monitoring of the fluctuation of tracheal NO concentrations in a given patient could thus be a reliable 'marker' of pulmonary function during the course of ARDS... A display of tracheal NO concentration on the monitor screen is available on the latest chemiluminescence apparatus (EVA 4000, Sérès, Aix-en-Provence, France) giving the possibility of continuously monitoring the fluctuations in tracheal NO concentration as an index of 'pulmonary function' during the course of ARDS... In 1998, inhaled NO should be administered in such a way that stable and predictable concentrations in the inspiratory limb are obtained... It can, therefore, be considered as an index of ventilatory perfusion ratio mismatch, and can be continuously monitored in ARDS... In contrast, the continuous delivery of NO in the inspiratory limb leads to unpredictable and fluctuating concentrations of NO and must be considered as an unsafe mode of administration, unless fast-response chemiluminescence apparatus is used for monitoring.

No MeSH data available.