Optimal Flow Pattern for Mechanical Ventilation of the Lungs. 2. The Effect of a Sine Versus Square Wave Flow Pattern with and without an End-Inspiratory Pause on Patients

Dammann, J. Francis; McAslan, T. Crawford; Maffeo, Charles J.

doi:10.1097/00132586-197910000-00013

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“…Our results agree with previous findings that a postinspiratory pause enhances CO 2 elimination (Fuleihan et al, 1976;Dammann et al, 1978;Lachmann et al, 1982;Wolff et al, 1989a;Mercat et al, 2001). In the present study, we used the shortest possible tubing (compliance 0AE45 ml per cm H 2 O).…”

Section: Discussionsupporting

confidence: 92%

“…1) dictates that any symmetrical inspiratory waveform will have the same MDT, provided that inspiratory time is constant. The validity of this assumption is supported by that ventilation with square and sine inspiratory waveforms give rise to the same CO 2 elimination reflected by equal PaCO 2 (Dammann et al, 1978). Notably, a decelerating or accelerating inspiratory flow pattern will have longer and shorter MDT, respectively, compared to symmetrical flow waveforms.…”

Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

“…Rather than the term Ôanatomical dead spaceÕ we prefer the term airway dead space that should be read as Ôfunctional airway dead spaceÕ. Several studies in health or in disease show a decrease in dead space or PaCO 2 when using a postinspiratory pause (Fuleihan et al, 1976;Dammann et al, 1978;Lachmann et al, 1982;Wolff et al, 1989a;Mercat et al, 2001). However, positive effects of inspiratory patterns intended to improve gas exchange have not always been observed (Johansson, 1975;Johansson & Lo¨fstro¨m, 1975;Dammann et al, 1978;Al-Saady & Bennett, 1985;Markstro¨m et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…Several studies in health or in disease show a decrease in dead space or PaCO 2 when using a postinspiratory pause (Fuleihan et al. , 1976; Dammann et al. , 1978; Lachmann et al.…”

Section: Introductionmentioning

confidence: 99%

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A prolonged postinspiratory pause enhances CO₂ elimination by reducing airway dead space

Uttman

Jonson

2003

Clin Physio Funct Imaging

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SummaryBackground: CO 2 elimination per breath (V CO 2 , T ) depends primarily on tidal volume (V T ). The time course of flow during inspiration influences distribution and diffusive mixing of V T and is therefore a secondary factor determining gas exchange. To study the effect of a postinspiratory pause we defined Ômean distribution timeÕ (MDT) as the mean time given to inspired gas for distribution and diffusive mixing within the lungs. The objective was to quantify changes in airway dead space (V Daw ), slope of the alveolar plateau (SLOPE) and V CO 2 , T as a function of MDT in healthy pigs. Methods: Ten healthy pigs were mechanically ventilated. Airway pressure, flow and partial pressure of CO 2 were recorded during resetting of the postinspiratory pause from 10% (baseline) to, in random order, 0, 5, 20 and 30% of the respiratory cycle. The immediate changes in V Daw , SLOPE, V CO 2 , T , and MDT after resetting were analyzed. Results: V Daw in percent of V T decreased from 29 to 22%, SLOPE from 0AE35 to 0AE16 kPa per 100 ml as MDT increased from 0AE51 to 1AE39 s. Over the same MDT range, V CO 2 ,T increased by 10%. All these changes were statistically significant. Conclusion: MDT allows comparison of different patterns of inspiration on V Daw and gas exchange. Estimation of the effects of an altered ventilator setting on exchange of CO 2 can be done only after about 30 minutes, while the transient changes in V CO 2 ,T may give immediate information. MDT affects gas exchange to an important extent. Further studies in human subjects in health and in disease are needed.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Several studies in health or in disease show a decrease in dead space or PaCO 2 when using a postinspiratory pause (Fuleihan et al. , 1976; Dammann et al. , 1978; Lachmann et al.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A prolonged postinspiratory pause enhances CO₂ elimination by reducing airway dead space

Uttman

Jonson

2003

Clin Physio Funct Imaging

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Optimal Flow Pattern for Mechanical Ventilation of the Lungs. 2. The Effect of a Sine Versus Square Wave Flow Pattern with and without an End-Inspiratory Pause on Patients

Cited by 1 publication

References 0 publications

A prolonged postinspiratory pause enhances CO₂ elimination by reducing airway dead space

A prolonged postinspiratory pause enhances CO₂ elimination by reducing airway dead space

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Optimal Flow Pattern for Mechanical Ventilation of the Lungs. 2. The Effect of a Sine Versus Square Wave Flow Pattern with and without an End-Inspiratory Pause on Patients

Cited by 1 publication

References 0 publications

A prolonged postinspiratory pause enhances CO2 elimination by reducing airway dead space

A prolonged postinspiratory pause enhances CO2 elimination by reducing airway dead space

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A prolonged postinspiratory pause enhances CO₂ elimination by reducing airway dead space

A prolonged postinspiratory pause enhances CO₂ elimination by reducing airway dead space