How does positive end-expiratory pressure decrease CO2 elimination from the lung?

Breen, Peter H.; Mazumdar, Bhaskar

doi:10.1016/0034-5687(95)00089-5

Cited by 36 publications

(19 citation statements)

References 23 publications

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“…As can be seen from the formula used to calculate VD/VT, VD/VT is inversely related to CO 2 elimination. The elimination of CO 2 by the lung is influenced by effective alveolar surface area, alveolar ventilation and cardiac output (33,34). Following the RM and optimal PEEP, the CO 2 elimination capacity of the lung is increased, because alveolar ventilation is markedly increased.…”

Section: Discussionmentioning

confidence: 99%

Application of dead space fraction to titrate optimal positive end-expiratory pressure in an ARDS swine model

Bian

Chen

Chao

et al. 2017

Experimental and Therapeutic Medicine

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Abstract. This study aimed to apply the dead space fraction [ratio of dead space to tidal volume (VD/VT)] to titrate the optimal positive end-expiratory pressure (PEEP) in a swine model of acute respiratory distress syndrome (ARDS). Twelve swine models of ARDS were constructed. A lung recruitment maneuver was then conducted and the PEEP was set at 20 cm H 2 O. The PEEP was reduced by 2 cm H 2 O every 10 min until 0 cm H 2 O was reached, and VD/VT was measured after each decrement step. VD/VT was measured using single-breath analysis of CO 2 , and calculated from arterial CO 2 partial pressure (PaCO 2 ) and mixed expired CO 2 (PeCO 2 ) using the following formula: VD/VT = (PaCO 2 -PeCO 2 )/PaCO 2 . The optimal PEEP was identified by the lowest VD/VT method. Respiration and hemodynamic parameters were recorded during the periods of pre-injury and injury, and at 4 and 2 cm H 2 O below and above the optimal PEEP (Po). The optimal PEEP in this study was found to be 13.25±1.36 cm H 2 O. During the Po period, VD/VT decreased to a lower value (0.44±0.08) compared with that during the injury period (0.68±0.10) (P<0.05), while the intrapulmonary shunt fraction reached its lowest value. In addition, a significant change of dynamic tidal respiratory compliance and oxygenation index was induced by PEEP titration. These results indicate that minimal VD/VT can be used for PEEP titration in ARDS. IntroductionAcute respiratory distress syndrome (ARDS) is a severe and life-threatening medical condition that is common in critically ill patients and has a high mortality rate (1). It is a main reason for acute respiratory failure, and is characterized by widespread inflammation in the lungs (1,2). ARDS can induce pathophysiological mechanisms of alveolar collapse, hyoxemia, vascular dysfunction and elevated dead space fraction [the ratio of dead space volume to tidal volume (VD/VT)] (3,4).Currently, the lung-protection strategy for ventilation involves the use of high positive end-expiratory pressure (PEEP) levels combined with low tidal volumes to prevent end expiratory alveolar collapse, increase functional residual capacity, reduce VD/VT and attenuate hypoxemia (5,6). However, the application of higher levels of PEEP may not be necessarily beneficial, since it increases the inflation of lung regions. Additionally, it will also increase the risk of hemodynamic abnormalities as well as the lung injury induced by ventilation (7,8). Numerous studies have attempted to define the optimal PEEP level on the basis of a variety of methods during a recruitment maneuver (RM) with decreasing PEEP (9-11).A number of studies have applied the VD/VT method to assess the effects of lung recruitment and PEEP titration in patients with severe ARDS (9-11). VD/VT is a specific value based on the relatively high diffusibility of CO 2 across tissue membranes (12), and the exchange of CO 2 depends strictly on alveolar ventilation volume (13). However, some studies did not find a similar effect on VD/VT during PEEP titration (14,15). Therefore, the applic...

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Section: Discussionmentioning

confidence: 99%

Application of dead space fraction to titrate optimal positive end-expiratory pressure in an ARDS swine model

Bian

Chen

Chao

et al. 2017

Experimental and Therapeutic Medicine

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“…However, when PEEP is administered to recruit collapsed lung units (resulting in improved oxygenation), alveolar V D decreases unless overdistention impairs alveolar perfusion. Breen and Mazumdar 47 found that the application of PEEP at 11 cm H 2 O to anesthetized, mechanically ventilated, openchested dogs increased physiologic V D , reduced V eCO 2 , and resulted in a poorly defined alveolar plateau. These changes were mainly produced by a significant decrease in cardiac output due to PEEP.…”

Section: Effect Of V Tmentioning

confidence: 99%

The Physiology of Ventilation

Murias¹,

Blanch

Lucangelo

2014

Respir Care

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“…Accordingly, the PA̅E̅CO 2 [2,3], which is the volume-averaged alveolar PCO 2 , is a better index of PACO 2 than is PETCO 2 , which is just a single measurement of PCO 2 at the end of exhalation [2]. A more informative determination of pulmonary carbon dioxide elimination is VCO 2,br , which is starting to garner clinical acceptance.…”

Section: Introductionmentioning

confidence: 99%

Untitled

2000

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Greater understanding of the pathophysiology of carbon dioxide kinetics during steady and nonsteady state should improve, we believe, clinical care during intensive care treatment. Capnography and the measurement of end-tidal partial pressure of carbon dioxide (PETCO 2 ) will gradually be augmented by relatively new measurement methodology, including the volume of carbon dioxide exhaled per breath (VCO 2,br ) and average alveolar expired PCO 2 (PAE -CO 2 ). Future directions include the study of oxygen kinetics.

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How does positive end-expiratory pressure decrease CO2 elimination from the lung?

Cited by 36 publications

References 23 publications

Application of dead space fraction to titrate optimal positive end-expiratory pressure in an ARDS swine model

Application of dead space fraction to titrate optimal positive end-expiratory pressure in an ARDS swine model

The Physiology of Ventilation

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