A study of mixing conditions during nitric oxide administration using simultaneous fast response chemiluminescence and capnography

Foubert, L.; Mareels, K; Fredholm, M.; Lundin, S.; Stenqvist, O.

doi:10.1093/bja/78.4.436

Cited by 10 publications

(5 citation statements)

References 6 publications

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“…300-1000 ppm) accumulates during expiration at the injection site, creating a bolus which is transported and diluted along the respiratory system during inspiration. Therefore, it is not surprising that for CFS, very high peak NO meas exceeding NO target by factors of 2.4, 16 3.0 6 and 5.0 5 13 have been reported. This large variability between observed peak NO meas may be explained by different measurement technologies, such as fast-vs slow-response chemiluminescence 14 16 or by the use of a tracer gas such as nitrogen 6 or carbon dioxide 5 13 (instead of nitric oxide) which provide the advantage of rapid analysis.…”

Section: Discussionmentioning

confidence: 97%

Performance of proportional and continuous nitric oxide delivery systems during pressure- and volume-controlled ventilation

Hiesmayr

Neugebauer

Lassnigg

et al. 1998

British Journal of Anaesthesia

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We have evaluated the effect of delivering nitric oxide using a continuous flow system (CFS) or two commercially available proportional gas injection systems (PGIS), Nodomo (Dräger, Lübeck, Germany) and Pulmonox-Mini (Messer Griesheim Austria, Gumpoldskirchen, Austria) on measured and simulated concentrations of nitric oxide. Nitric oxide concentration was measured in a bench test at five sites in the inspiratory breathing system during volume- or pressure-controlled ventilation and mathematically simulated using a mixing chamber model. For a target concentration of 10 parts per million (ppm) at the "Y" piece, simulated nitric oxide concentrations were 1.9-139 ppm for CFS, 0.3-22 ppm for the Nodomo and 0.0-31 ppm for the Pulmonox-Mini near the nitric oxide administration site. However, peak concentrations decreased rapidly along the inspiratory system. Measured and simulated variations depended on the nitric oxide delivery system, site of measurement and tidal volume. Measured variations were four times smaller in the Nodomo than in the Pulmonox-Mini and CFS. As inappropriate mixing may occur even with PGIS, nitric oxide should probably not be administered near the "Y" piece.

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Section: Discussionmentioning

confidence: 97%

Performance of proportional and continuous nitric oxide delivery systems during pressure- and volume-controlled ventilation

Hiesmayr

Neugebauer

Lassnigg

et al. 1998

British Journal of Anaesthesia

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“…The NO concentrations measured by the analyser are low compared with the calculated level. There are well documented problems of continuous flow infusion into an intermittent flow ventilator[10–14]. As the NO was infused continuously, it presumably is delivered in relatively concentrated ‘boluses’ with a peak and trough pattern.…”

Section: Discussionmentioning

confidence: 99%

“…Many studies have attempted to determine the behaviour of NO and devise an optimal delivery system[8–10]. Although NO equipped ventilators are now available commercially, there is concern that commonly used delivery systems produce widely variable NO concentrations[10], particularly when combining continual infusion and intermittent flow ventilators[11–14]. These factors tend to produce a ‘bolus’ effect.…”

Section: Introductionmentioning

confidence: 99%

Nitric oxide delivery to the lung: a model

Jones¹,

Hooper²,

Stopp³

et al. 2000

Eur J Anaesthesiol

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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 time-cycled, pressure regulated, flow generating ventilator attached to a model infant-sized lung. The measured nitric oxide concentrations were always less than calculated. Infusion site, minute ventilation and sampling port all affected nitric oxide concentration (P < 0.05). Increasing minute ventilation 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 ventilator 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 measured.

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“…Alternatively, NO can be delivered into the inspiratory limb of the ventilator to reduce the contact time between NO and O 2 [8,[17][18][19][20][21]. However, with these techniques there is considerable concern about fluctuations in inspired NO concentrations [22][23][24]. Our data suggest that NO 2 production within a ventilator circuit depends on three important variables: the delivered NO concentration, the inspired NO concentration and the residence time of NO within the circuit.…”

Section: Discussionmentioning

confidence: 99%

Effect of nitric oxide predilution on inhaled nitrogen dioxide concentrations

Foubert¹,

Mareels²,

Blauwen³

et al. 1999

Anaesthesia

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SummaryWe examined the possibility that predilution of a concentrated nitric oxide (NO) source with nitrogen, before contact with oxygen, can reduce the inspired nitrogen dioxide (NO 2 ) concentration during administration of nitric oxide. A Manley Blease and a Siemens Servo 900 C ventilator delivered 10, 20, 40, 60 and 80 parts per million (ppm) NO using an NO source of 1000, 400 and 200 ppm. With the Manley Blease system, predilution from 1000 to 200 ppm NO reduced the inhaled NO 2 concentration from 0.14 to 0.05 ppm (p < 0.01) at 10 ppm inhaled NO, and from 1.20 to 1.00 ppm (p < 0.01) at 40 ppm inhaled NO. With the Siemens Servo 900 C ventilator, inspiratory NO 2 concentrations decreased from 0.21 to 0.11 ppm (p < 0.01) at 10 ppm inhaled NO, and from 1.49 to 1.16 ppm (p < 0.01) at 40 ppm NO. Predilution from 1000 to 400 ppm NO reduced the inspired NO 2 concentrations by < 3% using either ventilator when the inspirated NO concentration was 80 ppm. Predilution of NO with nitrogen significantly reduced the inspired NO 2 concentrations for nitric oxide concentrations between 10 and 40 ppm, but offered no clinically relevant advantage at higher NO concentrations. The discovery of the powerful vasodilator, endotheliumderived relaxing factor (EDRF) [1] and its subsequent identification as nitric oxide (NO) or a related nitrosocompound [2,3] has inspired numerous researchers to investigate the effects of this substance in a wide variety of pathological states. Inhaled NO causes selective dilatation of pulmonary blood vessels adjacent to ventilated alveoli [4,5] and is currently used for the treatment of acute lung injury, persistent pulmonary hypertension of the newborn (PPHN) and right ventricular failure after cardiac surgery [6][7][8][9][10].Methaemoglobinaemia is a potential toxic side-effect related to NO inhalation, but remains within safe limits in most of the clinical studies [4][5][6]11]. The free radical NO is rapidly oxidised to nitrogen dioxide (NO 2 ) in the presence of oxygen (O 2 ), which constitutes a considerable problem for its use as an inhalational agent. The conversion of NO to NO 2 is described by the relation,, where k is the rate constant [12].Assuming that the O 2 concentration is constant, integration of the formula gives the followingwhere [NO] 0 is the initial NO concentration, [NO] t is the NO concentration at time t and t is the residence time.Since the oxidation of NO is directly proportional to the square of its concentration, we hypothesise that the concentration of NO (i.e. the NO cylinder concentration or the delivered NO concentration) at its first contact with O 2 influences the inspired NO 2 concentration. We propose an oxidation mechanism which comprises two phases. Initially there is a 'point oxidation' at the first contact point between NO and the O 2 -air mixture. High NO concentrations at this point will result in significant NO 2 generation compared with lower NO concentrations. A second wave of oxidation begins when the different gases are mixed to produce a clinical con...

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A study of mixing conditions during nitric oxide administration using simultaneous fast response chemiluminescence and capnography

Cited by 10 publications

References 6 publications

Performance of proportional and continuous nitric oxide delivery systems during pressure- and volume-controlled ventilation

Performance of proportional and continuous nitric oxide delivery systems during pressure- and volume-controlled ventilation

Nitric oxide delivery to the lung: a model

Effect of nitric oxide predilution on inhaled nitrogen dioxide concentrations

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