Work of breathing

Mancebo, Jordi

doi:10.1007/3-540-37363-2_3

Cited by 4 publications

(4 citation statements)

References 17 publications

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“…7 Finally, in vivo, it must be remembered that respiratory muscle work is a major contributor to VCO 2 and if CO 2 is partially cleared extracorporeally, respiratory work and hence CO 2 production is likely to decrease. 30,31…”

Section: Discussionmentioning

confidence: 99%

In-vitro performance of a low flow extracorporeal carbon dioxide removal circuit

2019

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Introduction: Extracorporeal gas exchange requires the passage of oxygen and carbon dioxide (CO2) across an artificial membrane. Current European Union regulations do not require the transfer to be assessed in models using clinically relevant haemoglobin, making it difficult for clinicians to understand the CO2 clearance of a membrane, and how it changes in relation to sweep gas flow through the membrane. The characteristics of membrane CO2 clearance are described using a single membrane at different sweep gas flows in an in vitro model with clinically relevant haemoglobin concentrations using three separate methods of calculating CO2 clearance. Methods: To define the CO2 removal characteristics of the extra-corporeal CO2 removal (ECCO2R) device, we devised an in-vitro gas exchange circuit formed by a dedicated ECCO2R circuit (ALung, Pittsburgh, USA) in series with two membrane oxygenators. The system was primed with donated expired human red cells provided by the local blood bank. The experimental set-up allowed constant CO2 input (via one membrane oxygenator) with variable removal from a portion of the blood in a manner which was analogous to that seen in vivo. Blood gases were measured from different ports in the circuit in order to measure the experimental membrane CO2 clearance (VCO2). Results: Results demonstrate that the relationship between VCO2 and gas flow at a constant blood flow of 0.4 L/minute with a haemoglobin of 7 g/dL increases sharply from a gas flow of 0 to 2 L/min but plateaus at gas flows >4 L/minute. VCO2, calculated using three different methods, showed a strong linear correlation with minimal bias. Conclusions: The CO2 clearance of the membrane used in this bench test is non-linear. This has implications for clinical practice, especially during the weaning phase of the device.

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Section: Discussionmentioning

confidence: 99%

In-vitro performance of a low flow extracorporeal carbon dioxide removal circuit

2019

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“…Stratified analysis was used to evaluate the effects of age, respiratory compliance and resistance, PaO 2 /FiO 2 ratio and underlying disease on post-SBT responses. Comparing the responses to a T-tube trial and PS-6, the patients with old age, poor pulmonary compliance (≤40 ml/cmH 2 O) and chronic obstructive pulmonary disease had a higher heart rate (difference [95% CI]: 4 [0,8], 5 [2,9], 5 [0,10] beats/ minute, respectively) and systolic blood pressure (10 [4,16], 11 [5,16], 7 [0,13] mmHg, respectively) after the T-tube trial. In conclusion, this research shows that old age and impaired respiratory mechanics contribute to different responses to spontaneous breathing trials with a T-tube and low-level pressure support.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies have indicated that T-tube and PS trials are comparable for predicting extubation outcomes in unselected patients 1,2 . However, inspiratory pressure and positive end-expiratory pressure (PEEP) significantly affect gas exchange, cardiovascular performance and work of breathing [4][5][6] . The differences in inspiratory pressure and PEEP between a T-tube and PS have raised the concern that SBT with low-level PS may tend to overestimate the ability of a patient to sustain spontaneous breathing 7,8 .…”

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confidence: 99%

Comparison of Physiological Responses to Spontaneous Breathing Trials with a T-Tube and Low-Level Pressure Support

Ruan

Kuo

et al. 2013

Anaesth Intensive Care

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Previous studies have shown that spontaneous breathing trials (SBT) with a T-tube or low-level pressure support are comparable. However, low-level pressure support may overestimate the ability of a patient to sustain spontaneous breathing, resulting in premature extubation. Understanding factors contributing to different responses by patients to the two SBT methods aids in clarifying the limitation of using low-level pressure support for SBT. We performed a prospective observational study in 80 consecutive adult patients with mechanical ventilation to identify the factors contributing to different responses of a patient to the two SBT methods. The 80 patients underwent both a T-tube trial and pressure support ventilation of 6 cmH2O (PS-6) on the day of extubation. Stratified analysis was used to evaluate the effects of age, respiratory compliance and resistance, PaO2/FiO2 ratio and underlying disease on post-SBT responses. Comparing the responses to a T-tube trial and PS-6, the patients with old age, poor pulmonary compliance (≤40 ml/cmH2O) and chronic obstructive pulmonary disease had a higher heart rate (difference [95% CI]: 4 [0,8], 5 [2,9], 5 [0,10] beats/minute, respectively) and systolic blood pressure (10 [4,16], 11 [5,16], 7 [0,13] mmHg, respectively) after the T-tube trial. In conclusion, this research shows that old age and impaired respiratory mechanics contribute to different responses to spontaneous breathing trials with a T-tube and low-level pressure support. Further studies are needed to compare the effectiveness of the two SBT methods in predicting successful extubation in such patient groups.

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“…Campbell [30,31] observed that any respiratory cycle corresponds to a loop cycle in the pressure-volume space and the area of the latter measures the work of breath (WOB) needed to produce the former. This consideration can be shifted in the pressure-flow space by observing that a constant flow (f ) and the corresponding volume (V ) are related on the basis of the equation V = f * δ t where δ t stands for the time interval.…”

Section: Asynchronies As Work Overloadsmentioning

confidence: 99%

An effective pressure–flow characterization of respiratory asynchronies in mechanical ventilation

Casagrande

Quintavalle

Fernández

et al. 2020

J Clin Monit Comput

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Work of breathing

Cited by 4 publications

References 17 publications

In-vitro performance of a low flow extracorporeal carbon dioxide removal circuit

In-vitro performance of a low flow extracorporeal carbon dioxide removal circuit

Comparison of Physiological Responses to Spontaneous Breathing Trials with a T-Tube and Low-Level Pressure Support

An effective pressure–flow characterization of respiratory asynchronies in mechanical ventilation

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