Pulmonary Capillary Blood Flow and Cardiac Output Measurement by Partial Carbon Dioxide Rebreathing in Patients with Acute Respiratory Distress Syndrome Receiving Lung Protective Ventilation

2010 ◽  
Vol 2010 ◽  
pp. 221-222
Author(s):  
M. Mathru
Keyword(s):  
Carbon Dioxide ◽  
Distress Syndrome ◽  
Protective Ventilation ◽  
Capillary Blood ◽  
Lung Protective Ventilation ◽  
Output Measurement ◽  
Pulmonary Capillary Blood Flow ◽  
Carbon Dioxide Rebreathing ◽  
Pulmonary Capillary ◽  
Pulmonary Capillary Blood

Cardiac output measurement using N2O uptake: a method to subtract cardiogenic oscillations

1983 ◽  
Vol 54 (5) ◽  
pp. 1427-1433
Author(s):  
W. T. Dawson ◽  
R. L. Johnson
Keyword(s):  
Blood Flow ◽  
Stroke Volume ◽  
Capillary Blood ◽  
Capillary Blood Flow ◽  
Output Measurement ◽  
Ventricular Stroke Volume ◽  
Pulmonary Capillary Blood Flow ◽  
Pulmonary Capillary ◽  
Pulmonary Capillary Blood ◽  
Cardiogenic Oscillations

Plethysmographic (box) methods using N2O uptake to measure pulmonary capillary blood flow, right ventricular stroke volume, and pulmonary arterial flow pulse conduction time have been complicated by the presence of so-called “cardiogenic oscillations” in the box flow records on air and N2O breathing. The exact cause of these oscillations is unknown but believed to be secondary to instantaneous changes in net blood flow into and out of the thorax during the cardiac cycle. We examined these oscillations and pulmonary capillary blood flow in normal human subjects in a flow plethysmograph using a pressure compensation circuit to extend the frequency response. The cardiogenic oscillations in flow recorded at the mouth (with glottis open) are much greater in amplitude and 90 degrees out of phase from those recorded from the plethysmograph. We derived a theoretical analysis of this and designed an analogue electrical circuit to enable us to eliminate these oscillations by electrical subtraction from the box flow record generated by N2O uptake in the pulmonary capillary bed. Measurements of pulmonary capillary blood flow and ventricular stroke volume using our method correlate with measurements made with acetylene-rebreathing blood flow measurements performed sequentially at the same sitting.

Effect of different pressure breathing patterns on alveolar-arterial gradients in dogs

1963 ◽  
Vol 18 (6) ◽  
pp. 1049-1052 ◽  
Author(s):  
Norman A. Bergman
Keyword(s):  
Carbon Dioxide ◽  
Blood Flow ◽  
Capillary Blood ◽  
Respiratory Cycle ◽  
Positive Pressure ◽  
Pulmonary Capillary Blood Flow ◽  
Pulmonary Capillary ◽  
Mean Pressure ◽  
Pulmonary Capillary Blood ◽  
Intermittent Positive Pressure Breathing

Arterial end-tidal carbon dioxide gradients were measured and alveolar-arterial oxygen gradients were estimated in dogs during intermittent positive pressure ventilation at constant inflating pressure using four curves having differing pressure profiles. The smallest gradients for both oxygen and carbon dioxide occurred when mean pressure during respiratory cycles was high and decreases in mean pressure were consistently associated with increases in both oxygen and carbon dioxide gradients. Profile of the applied pressure curve per se did not influence magnitude of the gradients. It is concluded that during intermittent positive pressure breathing, relative distribution of pulmonary capillary blood flow and inspired gas may vary with mean pressure during the respiratory cycle and is more uniform when mean pressure during the respiratory cycle is high. artificial ventilation; intermittent positive pressure breathing; alveolar-arterial; carbon dioxide gradient; distribution of inspired gas; pulmonary capillary blood flow Submitted on December 13, 1962

scholarly journals Pulmonary Capillary Blood Flow and Cardiac Output Measurement by Partial Carbon Dioxide Rebreathing in Patients with Acute Respiratory Distress Syndrome Receiving Lung Protective Ventilation

2009 ◽  
Vol 111 (5) ◽  
pp. 1085-1092 ◽  
Author(s):  
Jérôme Allardet-Servent ◽  
Jean-Marie Forel ◽  
Antoine Roch ◽  
Laurent Chiche ◽  
Christophe Guervilly ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Acute Respiratory Distress Syndrome ◽  
Respiratory Distress Syndrome ◽  
Distress Syndrome ◽  
Capillary Blood ◽  
Capillary Blood Flow ◽  
Pulmonary Capillary Blood Flow ◽  
Pulmonary Capillary ◽  
Pulmonary Capillary Blood

Background Partial carbon dioxide rebreathing noninvasively measures the pulmonary capillary blood flow and estimates the cardiac output with the use of a predicted shunt value. It has been reported that the accuracy of the method is decreased in patients with high pulmonary shunt. The aim of this study was to investigate the agreement between partial rebreathing and thermodilution for the determination of pulmonary capillary blood flow and cardiac output in the setting of acute respiratory distress syndrome. Methods Twenty consecutive patients with the acute respiratory distress syndrome were enrolled. Ventilator settings include low tidal volume (6 ml x kg(-1)) and positive end-expiratory pressure + 2 cm H2O higher than the lower inflection point if present or 10 cm H2O if not. Seven pairs of cardiac output and pulmonary capillary blood flows were recorded every 20 min over a 2-h period. The authors determined bias, SD, limit of agreement (95% confidence interval) and percentage error. Results Bias and agreement for cardiac output measurement were 0.8 +/- 1.2 l x min(-1) (-2.1 to 3.7 l x min(-1)), and percentage error was 36%. Bias and agreement for pulmonary capillary blood flow measurement were -0.1 +/- 0.8 l x min(-1) (-2.1 to 1.9 l x min(-1)), and percentage error was 35%. Dead space, arteriovenous oxygen content difference, mean pulmonary arterial pressure, and baseline cardiac output were independently associated with differences between methods. Conclusions In patients with the acute respiratory distress syndrome, partial rebreathing cannot yet replace thermodilution for measuring pulmonary capillary blood flow or cardiac output. However, accuracy of the method is close to the boundary of clinical relevance.

Gas Exchange

2017 ◽  
Author(s):  
John W. Kreit
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Partial Pressure ◽  
Capillary Blood ◽  
Pressure Gradients ◽  
Arterial Blood ◽  
Pulmonary Capillary ◽  
Partial Pressures ◽  
Pulmonary Capillary Blood ◽  
And Diffusion

Gas Exchange explains how four processes—delivery of oxygen, excretion of carbon dioxide, matching of ventilation and perfusion, and diffusion—allow the respiratory system to maintain normal partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) in the arterial blood. Partial pressure is important because O2 and CO2 molecules diffuse between alveolar gas and pulmonary capillary blood and between systemic capillary blood and the tissues along their partial pressure gradients, and diffusion continues until the partial pressures are equal. Ventilation is an essential part of gas exchange because it delivers O2, eliminates CO2, and determines ventilation–perfusion ratios. This chapter also explains how and why abnormalities in each of these processes may reduce PaO2, increase PaCO2, or both.

Sign in / Sign up

Export Citation Format

Share Document