Dataset Information

Use of airway pressure-based indices to detect high and low inspiratory effort during pressure support ventilation: a diagnostic accuracy study.

ABSTRACT:

Background

Assessment of the patient's respiratory effort is essential during assisted ventilation. We aimed to evaluate the accuracy of airway pressure (P_aw)-based indices to detect potential injurious inspiratory effort during pressure support (PS) ventilation.

Methods

In this prospective diagnostic accuracy study conducted in four ICUs in two academic hospitals, 28 adult acute respiratory failure patients undergoing PS ventilation were enrolled. A downward PS titration was conducted from 20 cmH₂O to 2 cmH₂O at a 2 cmH₂O interval. By performing an end-expiratory airway occlusion maneuver, the negative P_aw generated during the first 100 ms (P_0.1) and the maximal negative swing of P_aw (∆P_occ) were measured. After an end-inspiratory airway occlusion, P_aw reached a plateau, and the magnitude of change in plateau from peak P_aw was measured as pressure muscle index (PMI). Esophageal pressure was monitored and inspiratory muscle pressure (P_mus) and P_mus-time product per minute (PTP_mus/min) were used as the reference standard for the patient's effort. High and low effort was defined as P_mus > 10 and < 5 cmH₂O, or PTP_mus/min > 200 and < 50 cmH₂O s min^-1, respectively.

Results

A total of 246 levels of PS were tested. The low inspiratory effort was diagnosed in 145 (59.0%) and 136 (55.3%) PS levels using respective P_mus and PTP_mus/min criterion. The receiver operating characteristic area of the three P_aw-based indices by the respective two criteria ranged from 0.87 to 0.95, and balanced sensitivity (0.83-0.96), specificity (0.74-0.88), and positive (0.80-0.91) and negative predictive values (0.78-0.94) were obtained. The high effort was diagnosed in 34 (13.8%) and 17 (6.9%) support levels using P_mus and PTP_mus/min criterion, respectively. High receiver operating characteristic areas of the three P_aw-based indices by the two criteria were found (0.93-0.95). A high sensitivity (0.80-1.00) and negative predictive value (0.97-1.00) were found with a low positive predictive value (0.23-0.64).

Conclusions

By performing simple airway occlusion maneuvers, the P_aw-based indices could be reliably used to detect low inspiratory efforts. Non-invasive and easily accessible characteristics support their potential bedside use for avoiding over-assistance. More evaluation of their performance is required in cohorts with high effort.

SUBMITTER: Yang YL

PROVIDER: S-EPMC10643759 | biostudies-literature | 2023 Nov

REPOSITORIES: biostudies-literature

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Publications

Use of airway pressure-based indices to detect high and low inspiratory effort during pressure support ventilation: a diagnostic accuracy study.

Yang Yan-Lin YL Liu Yang Y Gao Ran R Song De-Jing DJ Zhou Yi-Min YM Miao Ming-Yue MY Chen Wei W Wang Shu-Peng SP Wang Yue-Fu YF Zhang Linlin L Zhou Jian-Xin JX

Annals of intensive care 20231113 1

<h4>Background</h4>Assessment of the patient's respiratory effort is essential during assisted ventilation. We aimed to evaluate the accuracy of airway pressure (P<sub>aw</sub>)-based indices to detect potential injurious inspiratory effort during pressure support (PS) ventilation.<h4>Methods</h4>In this prospective diagnostic accuracy study conducted in four ICUs in two academic hospitals, 28 adult acute respiratory failure patients undergoing PS ventilation were enrolled. A downward PS titrati ...[more]

PMID: 37955842

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Project description:BackgroundBedside assessment of low levels of inspiratory effort, which are probably insufficient to prevent muscle atrophy, is challenging. The flow index, which is derived from the analysis of the inspiratory portion of the flow-time waveform, has been recently introduced as a non-invasive parameter to evaluate the inspiratory effort. The primary objective of the present study was to provide an external validation of the flow index to detect low inspiratory effort.MethodsDatasets containing flow, airway pressure, and esophageal pressure (Pes)-time waveforms were obtained from a previously published study in 100 acute brain-injured patients undergoing pressure support ventilation. Waveforms data were analyzed offline. A low inspiratory effort was defined by one of the following criteria, work of breathing (WOB) less than 0.3 J/L, Pes-time product (PTPes) per minute less than 50 cmH2O•s/min, or inspiratory muscle pressure (Pmus) less than 5 cmH2O, adding "or occurrence of ineffective effort more than 10%" for all criteria. The flow index was calculated according to previously reported method. The association of flow index with Pes-derived parameters of effort was investigated. The diagnostic accuracy of the flow index to detect low effort was analyzed.ResultsModerate correlations were found between flow index and WOB, Pmus, and PTPes per breath and per minute (Pearson's correlation coefficients ranged from 0.546 to 0.634, P < 0.001). The incidence of low inspiratory effort was 62%, 51%, and 55% using the definition of WOB, PTPes per minute, and Pmus, respectively. The area under the receiver operating characteristic curve for flow index to diagnose low effort was 0.88, 0.81, and 0.88, for the three respective definition. By using the cutoff value of flow index less than 2.1, the diagnostic performance for the three definitions showed sensitivity of 0.95-0.96, specificity of 0.57-0.71, positive predictive value of 0.70-0.84, and negative predictive value of 0.90-0.93.ConclusionsThe flow index is associated with Pes-based inspiratory effort measurements. Flow index can be used as a valid instrument to screen low inspiratory effort with a high probability to exclude cases without the condition.

Project description:BackgroundThe driving pressure of the respiratory system is a valuable indicator of global lung stress during passive mechanical ventilation. Monitoring lung stress in assisted ventilation is indispensable, but achieving passive conditions in spontaneously breathing patients to measure driving pressure is challenging. The accuracy of the morphology of airway pressure (Paw) during end-inspiratory occlusion to assure passive conditions during pressure support ventilation has not been examined.MethodsRetrospective analysis of end-inspiratory occlusions obtained from critically ill patients during pressure support ventilation. Flow, airway, esophageal, gastric, and transdiaphragmatic pressures were analyzed. The rise of gastric pressure during occlusion with a constant/decreasing transdiaphragmatic pressure was used to identify and quantify the expiratory muscle activity. The Paw during occlusion was classified in three patterns, based on the differences at three pre-defined points after occlusion (0.3, 1, and 2 s): a "passive-like" decrease followed by plateau, a pattern with "clear plateau," and an "irregular rise" pattern, which included all cases of late or continuous increase, with or without plateau.ResultsData from 40 patients and 227 occlusions were analyzed. Expiratory muscle activity during occlusion was identified in 79% of occlusions, and at all levels of assist. After classifying occlusions according to Paw pattern, expiratory muscle activity was identified in 52%, 67%, and 100% of cases of Paw of passive-like, clear plateau, or irregular rise pattern, respectively. The driving pressure was evaluated in the 133 occlusions having a passive-like or clear plateau pattern in Paw. An increase in gastric pressure was present in 46%, 62%, and 64% of cases at 0.3, 1, and 2 s, respectively, and it was greater than 2 cmH2O, in 10%, 20%, and 15% of cases at 0.3, 1, and 2 s, respectively.ConclusionsThe pattern of Paw during an end-inspiratory occlusion in pressure support cannot assure the absence of expiratory muscle activity and accurate measurement of driving pressure. Yet, because driving pressure can only be overestimated due to expiratory muscle contraction, in everyday practice, a low driving pressure indicates an absence of global lung over-stretch. A measurement of high driving pressure should prompt further diagnostic workup, such as a measurement of esophageal pressure.

Project description:BackgroundIn pressure-controlled (PC) ventilation, tidal volume (V T) and transpulmonary pressure (P L ) result from the addition of ventilator pressure and the patient's inspiratory effort. PC modes can be classified into fully, partially, and non-synchronized modes, and the degree of synchronization may result in different V T and P L despite identical ventilator settings. This study assessed the effects of three PC modes on V T, P L , inspiratory effort (esophageal pressure-time product, PTPes), and airway occlusion pressure, P 0.1. We also assessed whether P 0.1 can be used for evaluating patient effort.MethodsProspective, randomized, crossover physiologic study performed in 14 spontaneously breathing mechanically ventilated patients recovering from acute respiratory failure (1 subsequently withdrew). PC modes were fully (PC-CMV), partially (PC-SIMV), and non-synchronized (PC-IMV using airway pressure release ventilation) and were applied randomly; driving pressure, inspiratory time, and set respiratory rate being similar for all modes. Airway, esophageal pressure, P 0.1, airflow, gas exchange, and hemodynamics were recorded.ResultsV T was significantly lower during PC-IMV as compared with PC-SIMV and PC-CMV (387 ± 105 vs 458 ± 134 vs 482 ± 108 mL, respectively; p < 0.05). Maximal P L was also significantly lower (13.3 ± 4.9 vs 15.3 ± 5.7 vs 15.5 ± 5.2 cmH2O, respectively; p < 0.05), but PTPes was significantly higher in PC-IMV (215.6 ± 154.3 vs 150.0 ± 102.4 vs 130.9 ± 101.8 cmH2O × s × min-1, respectively; p < 0.05), with no differences in gas exchange and hemodynamic variables. PTPes increased by more than 15% in 10 patients and by more than 50% in 5 patients. An increased P 0.1 could identify high levels of PTPes.ConclusionsNon-synchronized PC mode lowers V T and P L in comparison with more synchronized modes in spontaneously breathing patients but can increase patient effort and may need specific adjustments. Clinical Trial Registration Clinicaltrial.gov # NCT02071277.

Project description:ObjectivesLung- and diaphragm-protective ventilation is a novel concept that aims to limit the detrimental effects of mechanical ventilation on the diaphragm while remaining within limits of lung-protective ventilation. The premise is that low breathing effort under mechanical ventilation causes diaphragm atrophy, whereas excessive breathing effort induces diaphragm and lung injury. In a proof-of-concept study, we aimed to assess whether titration of inspiratory support based on diaphragm effort increases the time that patients have effort in a predefined "diaphragm-protective" range, without compromising lung-protective ventilation.DesignRandomized clinical trial.SettingMixed medical-surgical ICU in a tertiary academic hospital in the Netherlands.PatientsPatients (n = 40) with respiratory failure ventilated in a partially-supported mode.InterventionsIn the intervention group, inspiratory support was titrated hourly to obtain transdiaphragmatic pressure swings in the predefined "diaphragm-protective" range (3-12 cm H2O). The control group received standard-of-care.Measurements and main resultsTransdiaphragmatic pressure, transpulmonary pressure, and tidal volume were monitored continuously for 24 hours in both groups. In the intervention group, more breaths were within "diaphragm-protective" range compared with the control group (median 81%; interquartile range [64-86%] vs 35% [16-60%], respectively; p < 0.001). Dynamic transpulmonary pressures (20.5 ± 7.1 vs 18.5 ± 7.0 cm H2O; p = 0.321) and tidal volumes (7.56 ± 1.47 vs 7.54 ± 1.22 mL/kg; p = 0.961) were not different in the intervention and control group, respectively.ConclusionsTitration of inspiratory support based on patient breathing effort greatly increased the time that patients had diaphragm effort in the predefined "diaphragm-protective" range without compromising tidal volumes and transpulmonary pressures. This study provides a strong rationale for further studies powered on patient-centered outcomes.

Dataset Information

Use of airway pressure-based indices to detect high and low inspiratory effort during pressure support ventilation: a diagnostic accuracy study.

Background

Methods

Results

Conclusions

Publications

Use of airway pressure-based indices to detect high and low inspiratory effort during pressure support ventilation: a diagnostic accuracy study.

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