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Do spontaneous and mechanical breathing have similar effects on average transpulmonary and alveolar pressure? A clinical crossover study.

Bellani G, Grasselli G, Teggia-Droghi M, Mauri T, Coppadoro A, Brochard L, Pesenti A - Crit Care (2016)

Bottom Line: Overall, ΔPL was similar between CMV and PSV, but only loosely correlated.By contrast, the Palv profile was very different between CMV and SB; SB led to progressively more negative Palv during inspiration, and Palv became lower than the set positive end-expiratory pressure in nine of ten patients at low PSV.Under similar conditions of flow and volume, transpulmonary pressure change is similar between CMV and PSV.

View Article: PubMed Central - PubMed

Affiliation: Department of Health Science, University of Milan-Bicocca, Via Cadore, 48 20900, Monza, Italy. giacomo.bellani1@unimib.it.

ABSTRACT

Background: Preservation of spontaneous breathing (SB) is sometimes debated because it has potentially both negative and positive effects on lung injury in comparison with fully controlled mechanical ventilation (CMV). We wanted (1) to verify in mechanically ventilated patients if the change in transpulmonary pressure was similar between pressure support ventilation (PSV) and CMV for a similar tidal volume, (2) to estimate the influence of SB on alveolar pressure (Palv), and (3) to determine whether a reliable plateau pressure could be measured during pressure support ventilation (PSV).

Methods: We studied ten patients equipped with esophageal catheters undergoing three levels of PSV followed by a phase of CMV. For each condition, we calculated the maximal and mean transpulmonary (ΔPL) swings and Palv.

Results: Overall, ΔPL was similar between CMV and PSV, but only loosely correlated. The differences in ΔPL between CMV and PSV were explained largely by different inspiratory flows, indicating that the resistive pressure drop caused this difference. By contrast, the Palv profile was very different between CMV and SB; SB led to progressively more negative Palv during inspiration, and Palv became lower than the set positive end-expiratory pressure in nine of ten patients at low PSV. Finally, inspiratory occlusion holds performed during PSV led to plateau and Δ PL pressures comparable with those measured during CMV.

Conclusions: Under similar conditions of flow and volume, transpulmonary pressure change is similar between CMV and PSV. SB during mechanical ventilation can cause remarkably negative swings in Palv, a mechanism by which SB might potentially induce lung injury.

No MeSH data available.


Related in: MedlinePlus

Individual examples of airway and esophageal pressure tracings of pressure support breaths sampled during regular tidal ventilation (a) and one prolonged inspiratory hold (b). a For each selected breath, from the airway (ΔPaw) and esophageal (ΔPes) pressure swings we calculated the transpulmonary lung pressure (Plung) swings (ΔPL) as changes from the end expiration (dotted lines) at two time points of interest: the point of maximum ΔPL and the mean over inspiration (gray rectangular area). b Following an inspiratory hold, when the patient relaxes the inspiratory muscles, a plateau is seen in airway and esophageal pressure (arrows), whose differences from the end-expiratory level represent the elastic recoil pressure of the respiratory system and of the chest wall, respectively
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Fig1: Individual examples of airway and esophageal pressure tracings of pressure support breaths sampled during regular tidal ventilation (a) and one prolonged inspiratory hold (b). a For each selected breath, from the airway (ΔPaw) and esophageal (ΔPes) pressure swings we calculated the transpulmonary lung pressure (Plung) swings (ΔPL) as changes from the end expiration (dotted lines) at two time points of interest: the point of maximum ΔPL and the mean over inspiration (gray rectangular area). b Following an inspiratory hold, when the patient relaxes the inspiratory muscles, a plateau is seen in airway and esophageal pressure (arrows), whose differences from the end-expiratory level represent the elastic recoil pressure of the respiratory system and of the chest wall, respectively

Mentions: For the present study, the electrical activity of the diaphragm data and the periods of neurally adjusted ventilatory assist ventilation were not taken into account. Continuous tracings of PL were generated as Paw – Pes, where Paw and Pes are airway and esophageal pressure, respectively. As we preferred to avoid using absolute values for Pes, we always refer to ΔPL from the end-expiratory level (Fig. 1a). Analogously, a Pes decrease or increase (ΔPes) was calculated as the difference in Pes from the end-expiratory level (Fig. 1a).Fig. 1


Do spontaneous and mechanical breathing have similar effects on average transpulmonary and alveolar pressure? A clinical crossover study.

Bellani G, Grasselli G, Teggia-Droghi M, Mauri T, Coppadoro A, Brochard L, Pesenti A - Crit Care (2016)

Individual examples of airway and esophageal pressure tracings of pressure support breaths sampled during regular tidal ventilation (a) and one prolonged inspiratory hold (b). a For each selected breath, from the airway (ΔPaw) and esophageal (ΔPes) pressure swings we calculated the transpulmonary lung pressure (Plung) swings (ΔPL) as changes from the end expiration (dotted lines) at two time points of interest: the point of maximum ΔPL and the mean over inspiration (gray rectangular area). b Following an inspiratory hold, when the patient relaxes the inspiratory muscles, a plateau is seen in airway and esophageal pressure (arrows), whose differences from the end-expiratory level represent the elastic recoil pressure of the respiratory system and of the chest wall, respectively
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4862136&req=5

Fig1: Individual examples of airway and esophageal pressure tracings of pressure support breaths sampled during regular tidal ventilation (a) and one prolonged inspiratory hold (b). a For each selected breath, from the airway (ΔPaw) and esophageal (ΔPes) pressure swings we calculated the transpulmonary lung pressure (Plung) swings (ΔPL) as changes from the end expiration (dotted lines) at two time points of interest: the point of maximum ΔPL and the mean over inspiration (gray rectangular area). b Following an inspiratory hold, when the patient relaxes the inspiratory muscles, a plateau is seen in airway and esophageal pressure (arrows), whose differences from the end-expiratory level represent the elastic recoil pressure of the respiratory system and of the chest wall, respectively
Mentions: For the present study, the electrical activity of the diaphragm data and the periods of neurally adjusted ventilatory assist ventilation were not taken into account. Continuous tracings of PL were generated as Paw – Pes, where Paw and Pes are airway and esophageal pressure, respectively. As we preferred to avoid using absolute values for Pes, we always refer to ΔPL from the end-expiratory level (Fig. 1a). Analogously, a Pes decrease or increase (ΔPes) was calculated as the difference in Pes from the end-expiratory level (Fig. 1a).Fig. 1

Bottom Line: Overall, ΔPL was similar between CMV and PSV, but only loosely correlated.By contrast, the Palv profile was very different between CMV and SB; SB led to progressively more negative Palv during inspiration, and Palv became lower than the set positive end-expiratory pressure in nine of ten patients at low PSV.Under similar conditions of flow and volume, transpulmonary pressure change is similar between CMV and PSV.

View Article: PubMed Central - PubMed

Affiliation: Department of Health Science, University of Milan-Bicocca, Via Cadore, 48 20900, Monza, Italy. giacomo.bellani1@unimib.it.

ABSTRACT

Background: Preservation of spontaneous breathing (SB) is sometimes debated because it has potentially both negative and positive effects on lung injury in comparison with fully controlled mechanical ventilation (CMV). We wanted (1) to verify in mechanically ventilated patients if the change in transpulmonary pressure was similar between pressure support ventilation (PSV) and CMV for a similar tidal volume, (2) to estimate the influence of SB on alveolar pressure (Palv), and (3) to determine whether a reliable plateau pressure could be measured during pressure support ventilation (PSV).

Methods: We studied ten patients equipped with esophageal catheters undergoing three levels of PSV followed by a phase of CMV. For each condition, we calculated the maximal and mean transpulmonary (ΔPL) swings and Palv.

Results: Overall, ΔPL was similar between CMV and PSV, but only loosely correlated. The differences in ΔPL between CMV and PSV were explained largely by different inspiratory flows, indicating that the resistive pressure drop caused this difference. By contrast, the Palv profile was very different between CMV and SB; SB led to progressively more negative Palv during inspiration, and Palv became lower than the set positive end-expiratory pressure in nine of ten patients at low PSV. Finally, inspiratory occlusion holds performed during PSV led to plateau and Δ PL pressures comparable with those measured during CMV.

Conclusions: Under similar conditions of flow and volume, transpulmonary pressure change is similar between CMV and PSV. SB during mechanical ventilation can cause remarkably negative swings in Palv, a mechanism by which SB might potentially induce lung injury.

No MeSH data available.


Related in: MedlinePlus