The Concept of Deadspace With Special Reference to the Single Breath Test for Carbon Dioxide

Fletcher, Roger; Jonson, B.; Cumming, Gordon R.; Brew, J.S.

doi:10.1093/bja/53.1.77

Cited by 311 publications

(211 citation statements)

References 30 publications

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“…The determination of arterial-alveolar gradient of carbon dioxide was performed according to the following equation: P(a-et)CO 2 [13]; while the calculation of alveolar dead space fraction was made according to the equation: AVDSf = P(aet)CO 2 / PaCO 2 [11], where: PaCO 2 is the partial pressure of carbon dioxide in arterial blood, and PetCO 2 is the final pressure of carbon dioxide in the exhaled air. R: respiratory coefficient (0.8); P(A-a)O 2 normal < 10mmHg [7].…”

Section: Methodsmentioning

confidence: 99%

Embolia pulmonar quase fatal, um modelo experimental

Pereira¹,

Moreira²,

Paschoal³

et al. 2011

Rev Bras Cir Cardiovasc

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Embolia pulmonar quase fatal, um modelo experimental: variáveis hemodinâmicas, gasométricas e capnográficasNear-fatal pulmonary embolism in an experimental model: hemodynamic, gasometric and capnographic variables Abstract Introduction: Experimental studies on pulmonary embolism (PE) are usually performed under mechanical ventilation. Most patients with suspicion of PE enter the Emergency Services in spontaneous breathing and environmental air. Thus, under these conditions, measurements of hemodynamic, gasometric and capnographic variables contribute largely to a more specific comprehension of cardiopulmonary and gasometric alterations in the acute phase of the disease. Studies which evaluated animals under conditions are lacking.Objective: This study aimed to submit animals under spontaneous ventilation and without supplemental oxygen to PE.Methods: PE was induced in six pigs using autologous blood clots, and cardiorespiratory and gasometric records were performed before and after PE. The values of "near fatal" mean pulmonary arterial pressure (MPAP) were previously determined.Results Conclusion: In this model, the near fatal MPAP was from 2 to 2.5 times the basal MPAP; and the capnographic variables, associated with arterial and venous gasometry, showed effective in discriminating an acute obstructive profile.Descriptors: Pulmonary embolism. Hypertension, pulmonary. Capnography. Models, animal. Swine. ResumoIntrodução: Estudos experimentais de embolia pulmonar (EP) são habitualmente realizados sob ventilação mecânica. A maioria dos pacientes com suspeita de EP adentra os Serviços de Emergência em respiração espontânea e em ar ambiente. Assim, medidas das variáveis hemodinâmicas, gasométricas e capnográficas, nessas condições, em muito Universitária "Zeferino Vaz"

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Section: Methodsmentioning

confidence: 99%

Embolia pulmonar quase fatal, um modelo experimental

Pereira¹,

Moreira²,

Paschoal³

et al. 2011

Rev Bras Cir Cardiovasc

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“…Increasing CO 2 diffusion after the ARS moves the interface between convective-diffusive transport mouthward, thus decreasing the VDAW measured by Fowler's method 8 (Appendix I, available as Additional Material at www.cja-jca.org).…”

Section: Protocolmentioning

confidence: 99%

“…The SBT-CO 2 is closely related to the matching of pulmonary ventilation and perfusion giving information on both the efficiency of ventilation and CO 2 exchange. [8][9][10] We hypothesized that a lung recruitment maneuver would reduce dead space. The aim of this work was to study the effect of PEEP, with and without a lung recruitment maneuver, on dead space analyzed with the SBT-CO 2 .…”

mentioning

confidence: 99%

Alveolar recruitment improves ventilatory efficiency of the lungs during anesthesia

Tusman

Böhm

Suárez-Sipmann

et al. 2004

Can J Anesth/J Can Anesth

108

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P Pu ur rp po os se e: : The goal of this study was to analyze the effect of positive end-expiratory pressure (PEEP), with and without a lung recruitment maneuver, on dead space.M Me et th ho od ds s: : 16 anesthetized patients were sequentially studied in three steps: 1) without PEEP (ZEEP), 2) with 5 cm H 2 O of PEEP and 3) with 5 cm H 2 O of PEEP after an alveolar recruitment strategy (ARS). Ventilation was maintained constant. The single breath test of CO 2 (SBT-CO 2 ), arterial oxygenation, end-expiratory lung volume (EELV) and respiratory compliance were recorded every 30 min.R Re es su ul lt ts s: : Physiological dead space to tidal volume decreased after ARS (0.45 ± 0.01) compared with ZEEP (0.50 ± 0.07, P < 0.05) and PEEP (0.51 ± 0.06, P < 0.05). The elimination of CO 2 per breath increased during PEEP (25 ± 3.3 mL·min -1 ) and ARS (27 ± 3.2 mL·min -1 ) compared to ZEEP (23 ± 2.6 mL·min -1 , P < 0.05), although ARS showed larger values than PEEP (P < 0.05). Pa-etCO 2 difference was lower after recruitment (0.9 ± 0.5 kPa, P < 0.05) compared to ZEEP (1.1 ± 0.5 kPa) and PEEP (1.2 ± 0.5 kPa).Slope II increased after ARS (63 ± 11%/L, P < 0.05) compared with ZEEP (46 ± 7.7%/L) and PEEP (56 ± 10%/L). Slope III decreased significantly after recruitment (0.13 ± 0.07 1/L) compared with ZEEP (0.21 ± 0.11 1/L) and PEEP (0.18 ± 0.10 1/L). The angle between slope II and III decreased only after ARS. After lung recruitment, PaO 2 , EELV, and compliance increased significantly compared with ZEEP and PEEP.

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“…The arterial oxygen partial pressure, P a , is used to calculate the total inspired ventilation according to Eq. (2), and from this _ V I 1 is found using (5). _ V I 1 is used to calculate the amount of expired ventilation, _ V E 1 from (6).…”

Section: Appendix A: the Solution Methodsmentioning

confidence: 99%

“…(2). However, an alveolar deadspace exists that arises due to causes distal to the alveolar-bronchiolar junction, which must be taken into consideration when determining _ V I 1 : 5,21 This comprises the effects due to both the mismatch of ventilation and perfusion within the poorly ventilated compartment, and uneven distribution of ventilation and perfusion between the healthy and unhealthy compartments. This is captured by the inclusion of a constant correction term, d s , that models the volume of gas that remains in the deadspace (see Fig.…”

Section: Ventilationmentioning

confidence: 99%

Modeling Alveolar Volume Changes During Periodic Breathing in Heterogeneously Ventilated Lungs

Dunn

Whiteley

2010

Ann Biomed Eng

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Abstract-A simplified model of periodic breathing, proposed by Whiteley et al. (Math. Med. Biol. 20:205-224, 2003), describes a non-uniform breathing pattern for a lung with an inhomogeneous gas distribution, such as that observed in some subjects suffering from respiratory disease. This model assumes a constant alveolar volume, and predicts incidence of irregular breathing caused by small, poorly ventilated regions of the lung. Presented here is an extension to this work which, by allowing variable lung volume, facilitates the investigation of pulmonary collapse in poorly ventilated compartments. A weakness of the original model is that a very small alveolar volume is required for periodic breathing to occur. The model presented within, which removes the assumption of constant compartment volume and allows alveolar volume to vary with time, predicts periodic breathing at higher, more realistic alveolar volumes. Furthermore, the predicted oscillations in ventilation match experimental data more closely. Thus the model that allows for alveolar collapse has improved upon these earlier results, and establishes a theoretical link between periodic breathing and atelectasis.

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The Concept of Deadspace With Special Reference to the Single Breath Test for Carbon Dioxide

Cited by 311 publications

References 30 publications

Embolia pulmonar quase fatal, um modelo experimental

Embolia pulmonar quase fatal, um modelo experimental

Alveolar recruitment improves ventilatory efficiency of the lungs during anesthesia

Modeling Alveolar Volume Changes During Periodic Breathing in Heterogeneously Ventilated Lungs

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