Skip to main content
Download PDF

Physiologic effects of prone positioning on gas exchange and ventilation-perfusion matching in awake patients with AHRF

BMC Pulmonary Medicine volume 24, Article number: 600 (2024) Cite this article

Abstract

Background

Prone positioning (PP) improves oxygenation in awake patients with acute hypoxemic respiratory failure (AHRF). However, the underlying mechanisms remain unclear in patients with diverse lung morphology. We aimed to determine the short-term effects of awake prone positioning (APP) in AHRF patients with focal and non-focal lung morphology.

Methods

This is a prospective physiological study. Twenty-four non-intubated patients with PaO2/FiO2 ≤ 300 mm Hg were included. Gas exchange, ventilation and perfusion distribution, and hemodynamics variables were recorded in the supine position (SP1), 2 h after PP, and 1 h after re-supine (SP2). Lung morphology was classified as focal and non-focal patterns using computed tomography.

Results

Twelve of the included patients were classified to the focal group and 12 to the non-focal group. PaO2/FiO2 improved after PP in all patients (161 [137, 227] mmHg vs. 236 [202, 275] mmHg, p < 0.001). Ventilation-perfusion (V/Q) matching increased after PP in all patients (61.9 [53.9, 66.5] vs. 77.5 [68.3, 80.0], p < 0.001). Shunt exhibited a significant decrease in patients of the non-focal group (28.6 [22.5, 30.3] vs. 11.3 [9.0, 14.5], p < 0.001), whereas no difference was found in the focal group after PP. Dead space decreased significantly in patients of the focal group (25.6 [21.5, 28.4] vs. 12.0 [10.8, 14.1], p < 0.001), whereas no difference was found in the non-focal group after PP.

Conclusions

APP improves V/Q matching, and large-scale, bias-free studies are needed to find more definitive differences between patients with focal and non-focal lung morphyology.

Trial registration

The study is registered in ClinicalTrials.gov (trial No. NCT04754113, date of registration: 2021-02-15).

Peer Review reports

Introduction

Prone positioning is an effective intervention to reduce mortality and has been commonly used for many years [1, 2]. Prone positioning reduces intrapulmonary shunt and facilitates lung recruitment, further optimizing ventilation/perfusion matching [3]. While the mechanisms behind the prone positioning are more complex. In mechanically ventilated patients, prone positioning improves oxygenation while achieving a more homogeneous distribution of the mechanical forces, therefore reducing lung injury [4, 5].

In recent years, the use of awake prone positioning in non-intubated patients with acute hypoxemic respiratory failure (AHRF) has been implemented in clinical practice due to its beneficial effect on the oxygenation and clinical outcomes [6,7,8,9]. However, the exact mechanisms leading to the oxygenation improvement remain unclear. Only few studies have addressed the physiological effects of prone positioning in awake patients, most of which have only demonstrated the change of regional distribution of ventilation and effort-to-breathe after proning [10,11,12].

As oxygenation improvement may involve changes in the distribution of either ventilation and/or perfusion that may both affect regional ventilation/perfusion (V/Q) matching, it is essential to consider the distribution of regional pulmonary blood flow following awake prone positioning [13]. Electrical impedance tomography (EIT), as a bedside, real-time, free-radiation technology, has been identified to detect pulmonary blood flow, particularly when using hypertonic saline as a “conductive” contrast agent [14]. Therefore, EIT is a useful tool for assessing the potential mechanisms affecting the distribution of both ventilation and perfusion during awake prone positioning. In recent, two crossover trials evaluated the effects of awake prone positioning using EIT. Both studies showed that while awake prone positioning improved oxygenation, it was not associated with improved lung ventilaton homogeneity [15, 16]. In this study, we use EIT to continuously record regional lung ventilation and perfusion in patients with AHRF and we hypothesize that the effects of awake prone positioning in improving V/Q matching by reducing shunt and dead space may differ among patients exhibiting diverse lung morphology.

Methods

This prospective observational study was performed in the medical ICU at Zhongda Hospital, Southeast University from May 2021 to March 2022. The study protocol was granted approval by the Institutional Ethics Committee of Zhongda hospital, Southeast University (2020ZDSYLL057-P01). Written informed consent was obtained from patients before enrollment. For patients who were unable to write due to underlying medical conditions, written informed consent were obtained from the patients’ legal representatives with their authorization. This was a prospective, observational cohort study registered in ClinicalTrials.gov (NCT04754113, date of registration: 2021-02-15).

Study population

All adults (> 18 years) admitted to our ICU were enrolled if they met the following criteria: (1) a ratio of the partial pressure of arterial oxygen (PaO2) to the FiO2 (PaO2/FiO2) ≤ 300 mm Hg while the patient was breathing oxygen at a flow rate of 10 L per minute or more for at least 15 min [17], (2) evidence of bilateral pulmonary infiltrates on a chest radiograph or a CT scan, (3) an acute onset (< 1 week) of respiratory distress, (4) a partial pressure of arterial carbon dioxide (PaCO2) ≤ 45 mm Hg, and (5) no history of chronic respiratory failure. Exclusion criteria were as follows: contraindication to EIT use (presence of pacemaker), prior intubation, contraindications to prone positioning, poor tolerance and/or severe worsening of clinical conditions during study phases necessitating prone positioning discontinuation, a lack of ability to hold the breath, a lack of central venous catheter, and refusal to participate in this study.

Study protocol

Demographic data (age, sex, body mass index [BMI]), cause of AHRF, type of supplemental oxygen, time from symptoms onset to hospital admission and ICU admission, and time from hospital admission to awake prone positioning were collected. Chest CT scan in the supine position was collected at enrollment. Upon enrollment, each patient was assigned to either standard oxygen therapy or high-flow nasal cannula (MR860 or ARIVO2, Fisher and Paykel healthcare), as determined by the clinical clinician. This assignment remained unchanged throughout the study period. All patients were examined in the supine position at baseline (SP1), 2 h after prone positioning initiation (PP), and 1 h after re-positioning to the supine posture (SP2). The respiratory rate (RR), peripheral capillary oxygen saturation (SpO2), arterial blood gas analysis (pH, PaO2, PaCO2, PaO2/FiO2), hemodynamic parameters (heart rate and mean arterial pressure), and EIT data were recorded during the last five-minute period of each of the three phases. The use of sedative or analgesic agents which could have interfered with the breathing pattern was not allowed during the study period.

EIT data

EIT measurements were performed using PulmoVista 500 (Dräger Medical GmbH, Lübeck, Germany) at 50 Hz and the data were stored for offline analysis. The 16-electrode EIT belt was placed along the fourth to fifth intercostal space and kept in the same position during the whole study period. Regional ventilation maps were calculated by averaging tidal impedance variation (the difference between end-inspiratory and end-expiratory impedance) after the bolus during the last 1 min of the 5-min long data acquisition. Regional perfusion maps were generated by the slope of the impedance decrease with a saline bolus injection strategy [18]. The patients were asked to perform an end-expiratory breath-hold for 8–12 s, and then a bolus of 10 mL of 10% NaCl solution was quickly injected through a central venous catheter 2 s after the voluntary onset of airway occlusion. The following parameters were calculated in the last minute of each study phase: (1) the percentage of total ventilated lung area that is located in the dorsal half of the thorax [19], (2) the percentage of total perfused lung area that is located in the dorsal half of the thorax [19], (3) the global inhomogeneity (GI) index [20]. Subsequently, the following regions were identified [19]: (1) shunt %: all pixels that were only perfused, divided by the total number of pixels classified as ventilated or perfused. (2) dead space %: all pixels that were only ventilated, divided by the total number of pixels classified as ventilated or perfused. (3) V/Q matching %: corresponding to the pixels that were both ventilated and perfused divided by the total number of pixels ventilated or perfused.

Lung morphology assessment

The chest CT was obtained within 48 h prior to or following the onset of study period. All CT scans were performed in the supine position. CT images were analyzed by two intensivists and one radiologist who were blinded to patient’s history. Patterns of lung morphology were considered as “focal” in the presence of consolidations localized only in the lower lobes or gravitationally dependent parenchyma, and as “non-focal” if diffuse or patchy consolidations were identified in the lung parenchyma [21].

Endpoints

The primary endpoint was changes in V/Q matching with positions accroding to the CT pattern. The secondary endpoints were the percentage of shunt, the percentage of dead space, the percentage of dorsal ventilated area, the percentage of dorsal perfused area, the GI index, pH, PaO2, PaO2/FiO2, PaCO2, RR, heart rate, and mean arterial pressure in different positions. A patient was an oxygenation responder when a relative increase in PaO2/FiO2 by 20% or more was noted after prone positioning [11].

Statistical analysis

Considering the lack of previous studies’ results, sample size calculation was unattainable in our study. Data were tested for normality distribution by Shapiro-Wilk test. Continuous variables were reported as mean (± standard deviation) or median (interquartile range [IQR]) for continuous variables, as appropriate. Categorical variables were reported as numbers (percent). For the analysis of variables with normal distribution, Mauchly’s test was performed for sphericity, and repeated measures ANOVA was used with post hoc Bonferroni’s multiple comparisons. If not normally distributed, the change of variables at the different timepoints were compared using Kruskal-Wallis test. Greenhouse-Geisser method was applied for correction when Mauchly’s test p value was < 0.05. A level of two-tailed p < 0.05 was considered as statistically significant. Statistical analyses were conducted using STATA version 19.0 (Statacorp, College Station, TX, USA) and Prism (GraphPad Prism v9.3, La Jolla, CA).

Results

Patients’ characteristics

Twenty-four patients were enrolled in the study. Twelve patients were classified to the focal lung morphology group and twelve to the non-focal lung morphology group (Figure E1). The patients in the non-focal group were older than patients in the focal group (P = 0.037). The use of nasal oxygen was no difference between patients in the focal group and non-focal group (33% vs. 25%, P < 0.653). There were no significant differences in other characteristics between the two groups. Additional details are summarized in Table 1.

Table 1 Baseline characteristics of the study patients
Full size table

Comparisons between SP1 and PP

Gas exchange and hemodynamics variables

After proning, PaO2/FiO2 improved in both group (both P < 0.01) (Fig. 1A). Seven (54%) patients in the focal group and ten patients (91%) in the non-focal group were classified as oxygenation responders (Figure E2). pH and PaCO2 did not significantly change after PP in both groups. RR did not change between SP1 and PP (Table 2). For the hemodynamics variables, both heart rate and mean arterial pressure were not affected by the body position in both groups (Table 2).

Fig. 1
figure 1

Individual patients’ values of PaO2/FiO2 (A) and ventilation-perfusion match (B) during the three phases of the study. The thick black lines represent the median. SP1, supine at baseline; PP, prone position; SP, re-supine. *p < 0.05, **p < 0.01, ***p < 0.001

Full size image
Table 2 Gas exchange, EIT-related variables, and hemodynamics variables during the study period
Full size table

Ventilation, perfusion, and V/Q distribution

The change in the V/Q matching after PP is presented in the Table 2, Table E1, and Fig. 1B. V/Q matching increased significantly in both groups after proning (both p < 0.001). The percentages of shunt and dead sapce in SP1 and PP are presented in the Table 2; Fig. 2. For patients in the focal group, PP reduced the percentage of dead sapce but did not affect the percentage of shunt. Conversely, in patients in the non-focal group, PP reduced the percentage of shunt but did not impact the percentage of dead space.

Fig. 2
figure 2

Individual patients’ values of the percentage of shunt (A) and dead space (B) during the three phases of the study. The thick black lines represent the median. SP1, supine at baseline; PP, prone position; SP, re-supine. ***p < 0.001

Full size image

Comparisons between PP and SP2

Gas exchange and hemodynamics variables

For patients in both groups, PaO2/FiO2 decreased significantly in the SP2 when compared with PP (Fig. 1A). Patients in both groups were not different in the PaCO2 and RR between PP and SP2 (Table 2). Regarding the hemodynamics, neither heart rate nor mean arterial pressure in both groups showed any changes in the SP2 compared to PP (Table 2).

Ventilation, perfusion, and V/Q distribution

From PP to SP2, V/Q matching had significantly decreased in patients with both groups (Fig. 1B). For the percentage of shunt dead space, patients in both groups did not change from PP to SP2 (Fig. 2B).

The physiologic effects of awake prone positioning on the distribution of pulmonary ventilation and perfusion in two representative patients determined by EIT, are presented in the Figure E3 and Figure E4.

Subgroup analysis

To identify the effect of the type of supplemental oxygen (nasal oxygen vs. HFNC) and cause of AHRF (COVID-19 vs. Non-COVID-19) on the EIT-related variables. In patients with different types of supplemental oxygen, the results showed that patients with HFNC were more likely to benefit from APP based on gas exchange and ventilation-perfusion distribution (Table E2). In patients with different causes of AHRF, the result showed that APP could reduce the percent of dead space in the patients with COVID-19 (Table E3).

Correlations between change in PaO2/FiO2 and V/Q distribution

The relative variations in the PaO2/FiO2 during the PP session were inversely correlated with change in the percent of shunt (r = -0.46, P = 0.025) (Fig. 3B). However, no correlation was observed between the relative variations in the PaO2/FiO2 and the change in the percentage of V/Q matching (Fig. 3A) and dead space (Fig. 3C).

Fig. 3
figure 3

Correlation between difference of PaO2/FiO2 and ventilation-perfusion matching (A), shunt (B), and dead space (C). Difference of PaO2/FiO2 was defined as the change of PaO2/FiO2 from SP1 to PP. Each solid circle represents one patient with focal lung morphology. Each empty circle represents one patient with non-focal lung morphology. The dotted line represents 95% confidence intervals, while the solid line represents the regression line

Full size image

Discussion

The primary findings of this study are as follows: Awake prone positioning improved both V/Q matching and oxygenation in patients with AHRF, irrespective of lung morphology. Among patients with focal lung morphology, V/Q matching was improved by the reduced percentage of lung units with dead space ventilation. Among patients with non-focal lung morphology, V/Q matching was improved by the decreased percentage of shunt lung units.

The beneficial effect of awake prone positioning on the oxygenation improvement has been explored in several studies, especially in the context of the COVID-19 pandemic [11,12,13]. Nevertheless, discrepancies persist concerning oxygenation endpoints, the duration of prone positioning, and the respiratory support devices used in these studies [6, 9, 22]. A previous study reported that awake prone positioning induced a marked increase of PaO2/FiO2 of 20% or more in up to 85% of patients [23]. In the present study, we observed a significant increase in the PaO2/FiO2 at PP. Consistent with previous studies, our current study revealed that oxygenation improvement was independent of the baseline degree of hypoxemia, suggesting that basing the decisions on implementation of awake prone positioning on PaO2/FiO2 levels may not be reliable [23]. Furthermore, we confirmed that the effect of awake prone positioning on the oxygenation improvement was lost after repositioning to the supine posture, which was in line with previous studies [12, 13, 24]. Almost 70% of patients were classified as responders, showing a clinically significant increase in PaO2/FiO2 of 20% or more in the present study. This is comparable to the 65% reported in the previous study [11].

The physiological effects of awake prone positioning in the non-intubated patients with AHRF are not yet fully understood. In mechanically ventilated patients, following PP, the decrease of pleural pressure gradient from non-dependent to dependent regions reopens non-aerated or poorly aerated regions, therefore, reinforcing a more homogeneous ventilation [25]. Notably, in the present study, the GI index, which reflects lung inhomogeneity, showed no change following PP. This finding is consistent with results from two previous small trials [15, 16]. Therefore, the benefit in the oxygenation could be explained by the redistribution of pulmonary blood flow and optimisation of ventilation/perfusion matching.

In the present study, V/Q matching increased after awake prone positioning regardless of the lung morphology. However, there were still some differences in the effects of awake prone positioning among patients with different lung morphology, which were revealed in our study. The possible explaination for this discrepancy may included (1) The effect of HFNC: there was a slightly higher percentage of HFNC use with higher gas flow in patients with non-focal group, although the use of HFNC did not differ significantly between groups. The physiological effects of HFNC including reduced dead space, improved lung recruitment and oxygenation were associated with flow rate and change significantly with increases [26]. (2) Patient type: 60% of COVID-19 patients were included in our study. The CT patterns and lung lesions in COVID-19 patients could be differ compared to those with pneumonia or extrapulmonary sepsis. (3) The identification of EIT map: the shunt and dead space regions were identified using pixels for manual calculations, which may lead to calculation deviations. (4) A small sample size: we only included 12 patients in each group. The sample size may have been insufficient to detect a clinically significant treatment effect.

Our study has some limitations. First, the respiratory parameters, including esophageal pressure, trans-diaphragmatic pressure, tidal volume, and work of breathing was not measured which may affect the evaluation of the effects of awake prone positioning. Second, the long-term effects of awake prone positioning are missing, whether the short-term beneficial effects translate into improved clinically relevant outcome is unclear. Third, EIT cannot provide images of the whole lung, so the assessment of the entire spectrum of V/Q matching in the whole lung was not accessible. Forth, our study population was relatively small, but more than the sample size in previous studies on the physiological effect of awake prone positioning.

Conclusion

Awake prone positioning improves oxygenation and V/Q matching in AHRF patients regardless of lung morphology. Large-scale, bias-free studies are needed to find more definitive differences between patients with focal and non-focal lung morphology.

Data availability

The data that support the findings of this study are available upon reasonable request from the corresponding author.

Abbreviations

PP:

Prone positioning

APP:

Awark prone positioning

AHRF:

Acute hypoxemic respiratory failure

SP:

Supine positioning

PaO2 :

Partial pressure of arterial oxygen

PaCO2 :

Partial pressure of arterial carbon dioxide

EIT:

Eletrical impedance tomography

V/Q:

Ventilation-perfusion

BMI:

Body mass index

References

  1. Rampon GL, Simpson SQ, Agrawal R. Prone positioning for Acute Hypoxemic respiratory failure and ARDS: a review. Chest. 2023;163(2):332–40.

    Article  PubMed  Google Scholar 

  2. Guérin C, Reignier J, Richard JC, Beuret P, Gacouin A, Boulain T, Mercier E, Badet M, Mercat A, Baudin O, Clavel M, Chatellier D, Jaber S, Rosselli S, Mancebo J, Sirodot M, Hilbert G, Bengler C, Richecoeur J, Gainnier M, Bayle F, Bourdin G, Leray V, Girard R, Baboi L, Ayzac L, the PROSEVA Study Group. Prone positioning in severe acute respiratory distress syndrome. N Engl J Med. 2013;368:2159–68.

    Article  PubMed  Google Scholar 

  3. Fossali T, Pavlovsky B, Ottolina D, Colombo R, Basile MC, Castelli A, Rech R, Borghi B, Ianniello A, Flor N, Spinelli E, Catena E, Mauri T. Effects of prone position on lung recruitment and ventilation-perfusion matching in patients with COVID-19 acute respiratory distress syndrome: a Combined CT Scan/Electrical Impedance Tomography Study. Crit Care Med. 2022;50(5):723–32.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  4. Galiatsou E, Kostanti E, Svarna E, Kitsakos A, Koulouras V, Efremidis SC, Nakos G. Prone position augments recruitment and prevents alveolar overinflation in acute lung injury. Am J Respir Crit Care Med. 2006;174:187–97.

    Article  PubMed  Google Scholar 

  5. Cornejo RA, Díaz JC, Tobar EA, Bruhn AR, Ramos CA, González RA, Repetto CA, Romero CM, Gálvez LR, Llanos O, Arellano DH, Neira WR, Díaz GA, Zamorano AJ, Pereira GL. Effects of prone positioning on lung protection in patients with acute respiratory distress syndrome. Am J Respir Crit Care Med. 2013;188(4):440–8.

    Article  PubMed  Google Scholar 

  6. Ehrmann S, Li J, Ibarra-Estrada M, Perez Y, Pavlov I, McNicholas B, Roca O, Mirza S, Vines D, Garcia-Salcido R, Aguirre-Avalos G, Trump MW, Nay MA, Dellamonica J, Nseir S, Mogri I, Cosgrave D, Jayaraman D, Masclans JR, Laffey JG, Tavernier E. The Awake Prone Positioning Meta-Trial Group. Awake prone positioning for COVID-19 acute hypoxaemic respiratory failure: a randomised, controlled, multinational, open-label meta-trial. Lancet Respir Med. 2021;9(12):1387–95.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  7. Thompson AE, Ranard BL, Wei Y, Jelic S. Prone positioning in awake, nonintubated patients with COVID-19 hypoxemic respiratory failure. JAMA Intern Med. 2020;180:1537–9.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  8. osén J, von Oelreich E, Fors D, Jonsson Fagerlund M, Taxbro K, Skorup P, Eby L, Campoccia Jalde F, Johansson N, Bergström G, Frykholm P, PROFLO Study Group. Awake prone positioning in patients with hypoxemic respiratory failure due to COVID-19: the PROFLO multicenter randomized clinical trial. Crit Care. 2021;25(1):209.

    Article  Google Scholar 

  9. Coppo A, Bellani G, Winterton D, Di Pierro M, Soria A, Faverio P, Cairo M, Mori S, Messinesi G, Contro E, Bonfanti P, Benini A, Valsecchi MG, Antolini L, Foti G. Feasibility and physiological effects of prone positioning in non-intubated patients with acute respiratory failure due to COVID-19 (PRON-COVID): a prospective cohort study. Lancet Respir Med. 2020;8:765–74.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  10. Cammarota G, Rossi E, Vitali L, Simonte R, Sannipoli T, Anniciello F, Vetrugno L, Bignami E, Becattini C, Tesoro S, Azzolina D, Giacomucci A, Navalesi P, De Robertis E. Effect of awake prone position on diaphragmatic thickening fraction in patients assisted by noninvasive ventilation for hypoxemic acute respiratory failure related to novel coronavirus disease. Crit Care. 2021;25:305.

    Article  PubMed  PubMed Central  Google Scholar 

  11. Lehingue S, Allardet-Servent J, Ferdani A, Hraeich S, Forel JM, Arnal JM, Prud’homme E, Penaranda G, Bourenne J, Monnet O, Gainnier M, Cantais E. Physiologic effects of the awake prone position combined with high-flow nasal oxygen on gas exchange and work of breathing in patients with severe COVID-19 pneumonia: a randomized crossover trial. Crit Care Explor. 2022;4:e0805.

    Article  PubMed  PubMed Central  Google Scholar 

  12. Grieco DL, Delle Cese L, Menga LS, Rosà T, Michi T, Lombardi G, Cesarano M, Giammatteo V, Bello G, Carelli S, Cutuli SL, Sandroni C, De Pascale G, Pesenti A, Maggiore SM, Antonelli M. Physiological effects of awake prone position in acute hypoxemic respiratory failure. Crit Care. 2023;27:315.

    Article  PubMed  PubMed Central  Google Scholar 

  13. Liu L, Xie J, Wang C, Zhao Z, Chong Y, Yuan X, Qiu H, Zhao M, Yang Y, Slutsky AS. Prone position improves lung ventilation-perfusion matching in non-intubated COVID-19 patients: a prospective physiologic study. Crit Care. 2022;26:193.

    Article  PubMed  PubMed Central  Google Scholar 

  14. Frerichs I, Hinz J, Herrmann P, Weisser G, Hahn G, Quintel M. Regional lung perfusion as determined by electrical impedance tomography in comparison with electron beam CT imaging. IEEE Trans Med Imaging. 2002;21:646–52.

    Article  PubMed  Google Scholar 

  15. Rosén J, Frykholm P, Fagerlund MJ, Pellegrini M, Jalde FC, von Oelreich E, et al. Lung impedance changes during awake prone positioning in COVID-19. A non-randomized cross-over study. PLoS ONE. 2024;19(2):e0299199.

    Article  PubMed  PubMed Central  Google Scholar 

  16. Brunelle T, Prud’homme E, Alphonsine JE, Baumstarck K, Sanz C, Salmi S, et al. Awake prone position in COVID-19 acute respiratory failure: a randomised crossover study using electrical impedance tomography. ERJ Open Res. 2023;9(2):00509–2022.

    Article  PubMed  PubMed Central  Google Scholar 

  17. Frat JP, Thille AW, Mercat A, Girault C, Ragot S, Perbet S, Prat G, Boulain T, Morawiec E, Cottereau A, Devaquet J, Nseir S, Razazi K, Mira JP, Argaud L, Chakarian JC, Ricard JD, Wittebole X, Chevalier S, Herbland A, Fartoukh M, Constantin JM, Tonnelier JM, Pierrot M, Mathonnet A, Béduneau G, Delétage-Métreau C, Richard JCM, Brochard L, Robert R. The FLORALI Study Group and the REVA Network. High-flow oxygen through nasal cannula in acute hypoxemic respiratory failure. N Engl J Med. 2015;372:2185–96.

    Article  CAS  PubMed  Google Scholar 

  18. Borges JB, Suarez-Sipmann F, Bohm SH, Tusman G, Melo A, Maripuu E, Sandström M, Park M, Costa EL, Hedenstierna G, Amato M. Regional lung perfusion estimated by electrical impedance tomography in a piglet model of lung collapse. J Appl Physiol (1985). 2012; 112(1): 225 – 36.

  19. He H, Chi Y, Long Y, Yuan S, Zhang R, Yang Y, Frerichs I, Möller K, Fu F, Zhao Z. Three broad classifications of acute respiratory failure etiologies based on regional ventilation and perfusion by electrical impedance tomography: a hypothesis-generating study. Ann Intensive Care. 2021;11:1–12.

    Article  Google Scholar 

  20. Shono A, Kotani T. Clinical implication of monitoring regional ventilation using electrical impedance tomography. J Intensive Care. 2019;7:4.

    Article  PubMed  PubMed Central  Google Scholar 

  21. Puybasset L, Cluzel P, Gusman P, Grenier P, Preteux F, Rouby J. Regional distribution of gas and tissue in acute respiratory distress syndrome. Consequences for lung morphology. Int Care Med. 2000;26:857–69.

    Article  CAS  Google Scholar 

  22. Puybasset L, Gusman P, Muller JC, Cluzel P, Coriat P, Rouby JJ. Regional distribution of gas and tissue in acute respiratory distress syndrome. III. Consequences for the effects of positive end-expiratory pressure. CT scan ARDS Study Group. Adult respiratory distress syndrome. Intensive Care Med. 2000;26:1215–27.

    Article  CAS  PubMed  Google Scholar 

  23. Ferrando C, Mellado-Artigas R, Gea A, Arruti E, Aldecoa C, Adalia R, Ramasco F, Monedero P, Maseda E, Tamayo G, Hernández-Sanz ML, Mercadal J, Martín-Grande A, Kacmarek M, Villar R. Suárez-Sipmann F; for the COVID-19 Spanish ICU Network. COVID-19 Spanish ICU network. Awake prone positioning does not reduce the risk of intubation in COVID-19 treated with high-flow nasal oxygen therapy: a multicenter, adjusted cohort study. Crit Care. 2020;24:597.

    Article  PubMed  PubMed Central  Google Scholar 

  24. Chiumello D, Chiodaroli E, Coppola S, Cappio Borlino S, Granata C, Pitimada M, Wendel Garcia PD. Awake prone position reduces work of breathing in patients with COVID-19 ARDS supported by CPAP. Ann Intensive Care. 2021;11:179.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  25. Wang YX, Zhong M, Dong MH, Song JQ, Zheng YJ, Wu W, Tao JL, Zhu L, Zheng X. Prone positioning improves ventilation-perfusion matching assessed by electrical impedance tomography in patients with ARDS: a prospective physiological study. Crit Care. 2022;26:154.

    Article  PubMed  PubMed Central  Google Scholar 

  26. Delorme M, Bouchard PA, Simon M, Simard S, Lellouche F. Effects of High-Flow Nasal Cannula on the work of breathing in patients recovering from Acute Respiratory failure. Crit Care Med. 2017;45(12):1981–8.

    Article  CAS  PubMed  Google Scholar 

Download references

Acknowledgements

All authors were responsible for data interpretation, revised the manuscript critically, and approved the version submitted for publication.

Funding

This work was funded by National Science and Technology Major Project of China (2022YFC2504400), the National Natural Science Foundation of China (82341032 and 81930058), the Second Level Talents of the “333 High Level Talents Training Project” in the sixth phase in Jiangsu (LGY2022025), and Jiangsu Provincial Key Laboratory of Critical Care Medicine (BM2020004).

Author information

Author notes

  1. These authors contributed equally to this work.

Authors and Affiliations

  1. Jiangsu Provincial Key Laboratory of Critical Care Medicine, Department of Critical Care Medicine, School of Medicine, Zhongda Hospital, Southeast University, Nanjing, Jiangsu, 210009, China

    Yali Chao, Xueyan Yuan, Qin Sun, Dongyu Chen, Rui Zhang, Haibo Qiu & Ling Liu

  2. Department of Critical Care Medicine, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China

    Yali Chao

  3. Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany

    Zhanqi Zhao

  4. Department of Anesthesiology and Intensive Care Medicine, University Medical Center of Schleswig-Holstein Campus, Kiel, Germany

    Inéz Frerichs

  5. Department of Critical Care Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China

    Zhe Li

Authors
  1. Yali Chao
    View author publications

    You can also search for this author inPubMed Google Scholar

  2. Xueyan Yuan
    View author publications

    You can also search for this author inPubMed Google Scholar

  3. Zhanqi Zhao
    View author publications

    You can also search for this author inPubMed Google Scholar

  4. Inéz Frerichs
    View author publications

    You can also search for this author inPubMed Google Scholar

  5. Zhe Li
    View author publications

    You can also search for this author inPubMed Google Scholar

  6. Qin Sun
    View author publications

    You can also search for this author inPubMed Google Scholar

  7. Dongyu Chen
    View author publications

    You can also search for this author inPubMed Google Scholar

  8. Rui Zhang
    View author publications

    You can also search for this author inPubMed Google Scholar

  9. Haibo Qiu
    View author publications

    You can also search for this author inPubMed Google Scholar

  10. Ling Liu
    View author publications

    You can also search for this author inPubMed Google Scholar

Contributions

HQ and LL had the idea of the study, conceptualized the research aims, YC, ZZ, DC, and XY design the study and take responsibility for the integrity of the data and the accuracy of the data analysis. QS, RZ, and ZL performed the data processing and experimental analysis, XY doing the statistical analysis, YC and XY wrote the first draft of the paper, Inéz acquired the data and critically revised the manuscript. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Ling Liu.

Ethics declarations

Ethics approval and consent to participate

The study protocol was approved by the local ethics committee for clinical research of Zhongda Hospital, Southeast University (2020ZDSYLL057-P01). Written informed consent was obtained from patients before enrollment. For patients who were unable to write due to underlying medical conditions, written informed consent were obtained from the patients’ legal representatives with their authorization.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Electronic supplementary material

Below is the link to the electronic supplementary material.

Supplementary Material 1

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Chao, Y., Yuan, X., Zhao, Z. et al. Physiologic effects of prone positioning on gas exchange and ventilation-perfusion matching in awake patients with AHRF. BMC Pulm Med 24, 600 (2024). https://doiorg.publicaciones.saludcastillayleon.es/10.1186/s12890-024-03411-0

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doiorg.publicaciones.saludcastillayleon.es/10.1186/s12890-024-03411-0

Keywords

BMC Pulmonary Medicine

ISSN: 1471-2466

Contact us