Expiratory Flow Limitation Assessment in Patients with Acute Respiratory Distress Syndrome. A Reappraisal

Yonis, Hodane; Mortaza, Satar; Baboi, Loredana; Mercat, Alain; Guérin, Claude

doi:10.1164/rccm.201711-2326le

Cited by 25 publications

(20 citation statements)

References 10 publications

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“…Air trapping is defined as lung overdistension due to flow limitation in COPD/asthma/ARDS [37,38]. Two cases that reported using EIT technology could be useful to adjust an individual extra-PEEP of mechanical ventilation settings in severe asthma patients [38,39]. In the present study, we did not find any signs of air trapping by EIT (flow limitation) as the flow rate increased.…”

Section: Study Strengths and Limitationscontrasting

confidence: 39%

Effect of postextubation high-flow nasal cannula therapy on lung recruitment and overdistension in high-risk patient

Zhang

Long

et al. 2020

Crit Care

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Background: Postextubation high-flow nasal cannula (HFNC) is used as a support therapy in high-risk patients in ICU. This study aimed to determine the effects of HFNC therapy on lung recruitment and overdistension assessed by electrical impedance tomography (EIT). Methods: Twenty-four patients who received HFNC within 24 h after extubation were prospectively enrolled in this study. EIT was used to monitor regional lung ventilation distributions at baseline (conventional oxygen therapy) and three flow rate levels of HFNC therapy (20, 40, and 60 L/min). Change of end-expiratory lung impedance (ΔEELI), regional recruitment (recruited-pixels) and overdistension (overdistended-pixels), and lung strain change were determined by EIT. EIT images were equally divided into four ventral-to-dorsal horizontal regions of interest (ROIs 1, 2, 3, and 4). "Overdistensionby HFNC " due to HFNC is defined as an increase of overdistened-pixels > 10 than baseline. Patients were divided into two groups: (1) high potential of recruitment (HPR), recruited-pixels > 10 pixels at 60 L/min than baseline, and (2) low potential of recruitment (LPR), recruited-pixels < 10 pixels at 60 L/min than baseline. Results: When the flow rate gradually increased from baseline to 60 L/min, a significant and consistent increasing trend of global ΔEELI (%) (p < 0.0001), recruited-pixels (p < 0.001), and overdistended-pixels (p = 0.101) was observed. Moreover, the increase of ΔEELI was mainly distributed in ROI2 (p = 0.001) and ROI3 (p < 0.0001). The HPR group (13/24 patients) had significantly higher recruited-pixels than the LPR group (11/24 patients) at 20, 40, and 60 L/min. There were no significant differences in PaO 2 /FiO 2 , ΔEELI (%), and overdistention pixels between the two groups. The HPR group had 13 patients in which no one had "overdistensionby HFNC ", and the LPR group had 11 patients in which 4 patients had "overdistensionby HFNC " (0/13 vs. 4/11, p = 0.017). Conclusions: Using EIT could identify diverse effects of HFNC on lung regional ventilation in postextubation situations. Further study is required to validate using "HFNC effect" based on lung recruitment and overdistension by EIT in clinical practice. Trial registration: The study was retrospectively registered at www.clinicaltrials.gov (no. NCT04245241).

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Section: Study Strengths and Limitationscontrasting

confidence: 39%

Effect of postextubation high-flow nasal cannula therapy on lung recruitment and overdistension in high-risk patient

Zhang

Long

et al. 2020

Crit Care

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“…Airway closure with a variable degree of opening pressure has been documented in patients with acute respiratory distress syndrome, in human cadavers, and in cardiac arrest patients undergoing cardiopulmonary resuscitation. 1,4,23,24 Different from what initially suggested during general anesthesia, 6,7 the opening pressure is not an airway pressure threshold to overcome pleural pressure and generate positive transpulmonary pressure. Indeed, this phenomenon has been reported in the excised lung, where transpulmonary pressure is necessarily positive, 25,26 and in our study, airway opening often occurred at a transpulmonary pressure lower Fig.…”

Section: Discussionmentioning

confidence: 85%

“…Second, reported data are limited to 11 cases, and all patients were females, which cannot ensure the reproducibility of the findings among male patients. However, previous investigations in different settings 1,4,23 clearly showed that males may be similarly affected.…”

Section: Perioperative Medicinementioning

confidence: 90%

Airway Closure during Surgical Pneumoperitoneum in Obese Patients

Grieco¹,

Anzellotti²,

Russo³

et al. 2019

Anesthesiology

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Background: Airway closure causes lack of communication between proximal airways and alveoli, making tidal inflation start only after a critical airway opening pressure is overcome. The authors conducted a matched cohort study to report the existence of this phenomenon among obese patients undergoing general anesthesia.Methods: Within the procedures of a clinical trial during gynecological surgery, obese patients underwent respiratory/lung mechanics and lung volume assessment both before and after pneumoperitoneum, in the supine and Trendelenburg positions, respectively. Among patients included in this study, those exhibiting airway closure were compared to a control group of subjects enrolled in the same trial and matched in 1:1 ratio according to body mass index.results: Eleven of 50 patients (22%) showed airway closure after intubation, with a median (interquartile range) airway opening pressure of 9 cm H 2 O (6 to 12). With pneumoperitoneum, airway opening pressure increased up to 21 cm H 2 O (19 to 28) and end-expiratory lung volume remained unchanged (1,294 ml [1,154 to 1,363] vs. 1,160 ml [1,118 to 1,256], P = 0.155), because end-expiratory alveolar pressure increased consistently with airway opening pressure and counterbalanced pneumoperitoneum-induced increases in end-expiratory esophageal pressure (16 cm H 2 O [15 to 19] vs. 27 cm H 2 O [23 to 30], P = 0.005). Conversely, matched control subjects experienced a statistically significant greater reduction in end-expiratory lung volume due to pneumoperitoneum (1,113 ml [1,040 to 1,577] vs. 1,000 ml [821 to 1,061], P = 0.006). With airway closure, static/dynamic mechanics failed to measure actual lung/respiratory mechanics. When patients with airway closure underwent pressure-controlled ventilation, no tidal volume was inflated until inspiratory pressure overcame airway opening pressure.conclusions: In obese patients, complete airway closure is frequent during anesthesia and is worsened by Trendelenburg pneumoperitoneum, which increases airway opening pressure and alveolar pressure: besides preventing alveolar derecruitment, this yields misinterpretation of respiratory mechanics and generates a pressure threshold to inflate the lung that can reach high values, spreading concerns on the safety of pressure-controlled modes in this setting.

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“…Statistical analyses were performed using R [R version 3.5.2 (2018- [12][13][14][15][16][17][18][19][20]] with the meta, pROC and epi2 packages [9].…”

Section: Individual Data Analysismentioning

confidence: 99%

Positive end-expiratory pressure-induced recruited lung volume measured by volume-pressure curves in acute respiratory distress syndrome: a physiologic systematic review and meta-analysis

et al. 2020

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Purpose: Recruitment of lung volume is often cited as the reason for using positive end-expiratory pressure (PEEP) in acute respiratory distress syndrome (ARDS) patients. We performed a systematic review on PEEP-induced recruited lung volume measured from inspiratory volume-pressure (VP) curves in ARDS patients to assess the prevalence of patients with PEEP-induced recruited lung volume and the mortality in recruiters and non-recruiters. Methods: We conducted a systematic search of PubMed to identify studies including ARDS patients in which the intervention of an increase in PEEP was accompanied by measurement of the recruited volume (V rec increase versus no increase) using the VP curve in order to assess the relation between V rec and mortality at ICU discharge. We first analysed the pooled data from the papers identified and then analysed individual patient level data received from the authors via personal contact. The risk of bias of the included papers was assessed using the quality in prognosis studies tool and the certainty of the evidence regarding the relationship of mortality to V rec by the GRADE approach. Recruiters were defined as patients with a V rec > 150 ml. A random effects model was used for the pooled data. Multivariable logistic regression analysis was used for individual patient data. Results: We identified 16 papers with a total of 308 patients for the pooled data meta-analysis and 14 papers with a total of 384 patients for the individual data analysis. The quality of the articles was moderate. In the pooled data, the prevalence of recruiters was 74% and the mortality was not significantly different between recruiters and non-recruiters (relative risk 1.20 [95% confidence intervals 0.88-1.63]). The certainty of the evidence regarding this association was very low and publication bias evident. In the individual data, the prevalence of recruiters was 70%. In the multivariable logistic regression, V rec was not associated with mortality but Simplified Acute Physiology Score II and driving pressure at PEEP of 5 cmH 2 O were. Conclusion: After a PEEP increment, most patients are recruiters. V rec was not associated with ICU mortality. The presence of similar findings in the individual patient level analysis and the driving pressure at PEEP of 5 cmH 2 O was

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Expiratory Flow Limitation Assessment in Patients with Acute Respiratory Distress Syndrome. A Reappraisal

Cited by 25 publications

References 10 publications

Effect of postextubation high-flow nasal cannula therapy on lung recruitment and overdistension in high-risk patient

Effect of postextubation high-flow nasal cannula therapy on lung recruitment and overdistension in high-risk patient

Airway Closure during Surgical Pneumoperitoneum in Obese Patients

Positive end-expiratory pressure-induced recruited lung volume measured by volume-pressure curves in acute respiratory distress syndrome: a physiologic systematic review and meta-analysis

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