The EIT-based global inhomogeneity index is highly correlated with regional lung opening in patients with acute respiratory distress syndrome

BMC Research Notes

Knut Möller²  Ullrich Müller-Lisse¹  Inéz Frerichs⁴  Sven Pulletz³  Zhanqi Zhao¹ 

[1] Department of Radiology, University of Munich, Munich, Germany;Institute of Technical Medicine, Furtwangen University, Jakob-Kienzle Straße 17, D-78054 VS-Schwenningen, Germany;Department of Anaesthesiology and Intensive Care Medicine, Medical Center Osnabrück, Osnabrück, Germany;Department of Anaesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Kiel, Germany

关键词: Lung mechanics;    Regional lung opening;    Global inhomogeneity index;    Acute lung injury;    Electrical impedance tomography;   

Others  :  1134593
DOI  :  10.1186/1756-0500-7-82

 received in 2013-07-28, accepted in 2014-02-04,  发布年份 2014

【 摘 要 】

Background

The electrical impedance tomography (EIT)-based global inhomogeneity (GI) index was introduced to quantify tidal volume distribution within the lung. Up to now, the GI index was evaluated for plausibility but the analysis of how it is influenced by various physiological factors is still missing. The aim of our study was to evaluate the influence of proportion of open lung regions measured by EIT on the GI index.

Methods

A constant low-flow inflation maneuver was performed in 18 acute respiratory distress syndrome (ARDS) patients (58 ± 14 years, mean age ± SD) and 8 lung-healthy patients (41 ± 12 years) under controlled mechanical ventilation. EIT raw data were acquired at 25 scans/s and reconstructed offline. Recruited lung regions were identified as those image pixels of the lung regions within the EIT scans where local impedance amplitudes exceeded 10% of the maximum amplitude during the maneuver. A series of GI indices was calculated during mechanical lung inflation, based on the differential images obtained between different time points. Respiratory system elastance (E_rs) values were calculated at 10 lung volume levels during low-flow maneuver.

Results

The GI index decreased during low-flow inflation, while the percentage of open lung regions increased. The values correlated highly in both ARDS (r² = 0.88 ± 0.08, p < 0.01) and lung-healthy patients (r² = 0.92 ± 0.05, p < 0.01). E_rs and GI index were also significantly correlated in 16 out of 18 ARDS (r² = 0.84 ± 0.13, p < 0.01) and in 6 out of 8 lung-healthy patients (r² = 0.84 ± 0.07, p < 0.01). Significant differences were found in GI values between two groups (0.52 ± 0.21 for ARDS and 0.41 ± 0.04 for lung-healthy patients, p < 0.05) as well in E_rs values (0.017 ± 0.008 cmH₂O/ml for ARDS and 0.009 ± 0.001 cmH₂O/ml for lung-healthy patients, p < 0.01).

Conclusions

We conclude that the GI index is a reliable measure of ventilation heterogeneity highly correlated with lung recruitability measured with EIT. The GI index may prove to be a useful EIT-based index to guide ventilation therapy.

【 授权许可】

   
2014 Zhao et al.; licensee BioMed Central Ltd.

【 图 表 】

Figure 1.

Figure 2.

Figure 3.

Figure 4.

【 参考文献 】

• [1]Gattinoni L, D’Andrea L, Pelosi P, Vitale G, Pesenti A, Fumagalli R: Regional effects and mechanism of positive end-expiratory pressure in early adult respiratory distress syndrome. JAMA 1993, 269(16):2122-2127.
• [2]The Acute Respiratory Distress Syndrome Network: Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med 2000, 342(18):1301-1308.
• [3]Rouby JJ, Lu Q, Goldstein I: Selecting the right level of positive end-expiratory pressure in patients with acute respiratory distress syndrome. Am J Respir Crit Care Med 2002, 165(8):1182-1186.
• [4]Frerichs I, Dargaville PA, Dudykevych T, Rimensberger PC: Electrical impedance tomography: a method for monitoring regional lung aeration and tidal volume distribution? Intensive Care Med 2003, 29(12):2312-2316.
• [5]Brown BH, Barber DC, Morice AH, Leathard AD: Cardiac and respiratory related electrical impedance changes in the human thorax. IEEE Trans Biomed Eng 1994, 41(8):729-734.
• [6]Nopp P, Rapp E, Pfutzner H, Nakesch H, Ruhsam C: Dielectric properties of lung tissue as a function of air content. Phys Med Biol 1993, 38(6):699-716.
• [7]Frerichs I, Hinz J, Herrmann P, Weisser G, Hahn G, Quintel M, Hellige G: Regional lung perfusion as determined by electrical impedance tomography in comparison with electron beam CT imaging. IEEE Trans Med Imaging 2002, 21(6):646-652.
• [8]Hinz J, Neumann P, Dudykevych T, Andersson LG, Wrigge H, Burchardi H, Hedenstierna G: Regional ventilation by electrical impedance tomography: a comparison with ventilation scintigraphy in pigs. Chest 2003, 124(1):314-322.
• [9]Marquis F, Coulombe N, Costa R, Gagnon H, Guardo R, Skrobik Y: Electrical impedance tomography’s correlation to lung volume is not influenced by anthropometric parameters. J Clin Monit Comput 2006, 20(3):201-207.
• [10]Eyuboglu BM, Oner AF, Baysal U, Biber C, Keyf AI, Yilmaz U, Erdogan Y: Application of electrical impedance tomography in diagnosis of emphysema--a clinical study. Physiol Meas 1995, 16(3 Suppl A):A191-A211.
• [11]Lowhagen K, Lundin S, Stenqvist O: Regional intratidal gas distribution in acute lung injury and acute respiratory distress syndrome–assessed by electric impedance tomography. Minerva Anestesiol 2010, 76(12):1024-1035.
• [12]Miedema M, Frerichs I, de Jongh FH, van Veenendaal MB, van Kaam AH: Pneumothorax in a preterm infant monitored by electrical impedance tomography: a case report. Neonatology 2011, 99(1):10-13.
• [13]Victorino JA, Borges JB, Okamoto VN, Matos GF, Tucci MR, Caramez MP, Tanaka H, Sipmann FS, Santos DC, Barbas CS, Carvalho CR, Amato MB: Imbalances in regional lung ventilation: a validation study on electrical impedance tomography. Am J Respir Crit Care Med 2004, 169(7):791-800.
• [14]Frerichs I, Braun P, Dudykevych T, Hahn G, Genee D, Hellige G: Distribution of ventilation in young and elderly adults determined by electrical impedance tomography. Respir Physiol Neurobiol 2004, 143(1):63-75.
• [15]Frerichs I, Dudykevych T, Hinz J, Bodenstein M, Hahn G, Hellige G: Gravity effects on regional lung ventilation determined by functional EIT during parabolic flights. J Appl Physiol 2001, 91(1):39-50.
• [16]Zhao Z, Steinmann D, Frerichs I, Guttmann J, Möller K: PEEP titration guided by ventilation homogeneity: a feasibility study using electrical impedance tomography. Crit Care 2010, 14(1):R8. BioMed Central Full Text
• [17]Adler A, Amato MB, Arnold JH, Bayford R, Bodenstein M, Bohm SH, Brown BH, Frerichs I, Stenqvist O, Weiler N, et al.: Whither lung EIT: Where are we, where do we want to go and what do we need to get there? Physiol Meas 2012, 33(5):679-694.
• [18]Frerichs I, Pulletz S, Elke G, Gawelczyk B, Frerichs A, Weiler N: Patient examinations using electrical impedance tomography–sources of interference in the intensive care unit. Physiol Meas 2011, 32(12):L1-L10.
• [19]Lundin S, Stenqvist O: Electrical impedance tomography: potentials and pitfalls. Curr Opin Crit Care 2012, 18(1):35-41.
• [20]Moerer O, Hahn G, Quintel M: Lung impedance measurements to monitor alveolar ventilation. Curr Opin Crit Care 2011, 17(3):260-267.
• [21]Hinz J, Gehoff A, Moerer O, Frerichs I, Hahn G, Hellige G, Quintel M: Regional filling characteristics of the lungs in mechanically ventilated patients with acute lung injury. Eur J Anaesthesiol 2007, 24(5):414-424.
• [22]Wrigge H, Zinserling J, Muders T, Varelmann D, Gunther U, von der Groeben C, Magnusson A, Hedenstierna G, Putensen C: Electrical impedance tomography compared with thoracic computed tomography during a slow inflation maneuver in experimental models of lung injury. Crit Care Med 2008, 36(3):903-909.
• [23]Dargaville PA, Rimensberger PC, Frerichs I: Regional tidal ventilation and compliance during a stepwise vital capacity manoeuvre. Intensive Care Med 2010, 36(11):1953-1961.
• [24]Lowhagen K, Lindgren S, Odenstedt H, Stenqvist O, Lundin S: A new non-radiological method to assess potential lung recruitability: a pilot study in ALI patients. Acta Anaesthesiol Scand 2011, 55(2):165-174.
• [25]Grant CA, Fraser JF, Dunster KR, Schibler A: The assessment of regional lung mechanics with electrical impedance tomography: a pilot study during recruitment manoeuvres. Intensive Care Med 2009, 35(1):166-170.
• [26]Zhao Z, Möller K, Steinmann D, Frerichs I, Guttmann J: Evaluation of an electrical impedance tomography-based global inhomogeneity index for pulmonary ventilation distribution. Intensive Care Med 2009, 35(11):1900-1906.
• [27]Hough JL, Johnston L, Brauer SG, Woodgate PG, Pham TM, Schibler A: Effect of body position on ventilation distribution in preterm infants on continuous positive airway pressure. Pediatr Crit Care Med 2012, 13(4):446-451.
• [28]Humphreys S, Pham TM, Stocker C, Schibler A: The effect of induction of anesthesia and intubation on end-expiratory lung level and regional ventilation distribution in cardiac children. Paediatr Anaesth 2011, 21(8):887-893.
• [29]Zhao Z, Fischer R, Frerichs I, Müller-Lisse U, Möller K: Regional ventilation in cystic fibrosis measured by electrical impedance tomography. J Cyst Fibros 2012, 11(5):412-418.
• [30]Pulletz S, Adler A, Kott M, Elke G, Gawelczyk B, Schadler D, Zick G, Weiler N, Frerichs I: Regional lung opening and closing pressures in patients with acute lung injury. J Crit Care 2012, 27(3):323. e311-328
• [31]Adler A, Arnold JH, Bayford R, Borsic A, Brown B, Dixon P, Faes TJ, Frerichs I, Gagnon H, Garber Y, et al.: GREIT: a unified approach to 2D linear EIT reconstruction of lung images. Physiol Meas 2009, 30(6):S35-S55.
• [32]Pulletz S, van Genderingen HR, Schmitz G, Zick G, Schadler D, Scholz J, Weiler N, Frerichs I: Comparison of different methods to define regions of interest for evaluation of regional lung ventilation by EIT. Physiol Meas 2006, 27(5):S115-S127.
• [33]Barbas CS, de Matos GF, Pincelli MP, da Rosa Borges E, Antunes T, de Barros JM, Okamoto V, Borges JB, Amato MB, de Carvalho CR: Mechanical ventilation in acute respiratory failure: recruitment and high positive end-expiratory pressure are necessary. Curr Opin Crit Care 2005, 11(1):18-28.
• [34]Gattinoni L, Caironi P, Cressoni M, Chiumello D, Ranieri VM, Quintel M, Russo S, Patroniti N, Cornejo R, Bugedo G: Lung recruitment in patients with the acute respiratory distress syndrome. N Engl J Med 2006, 354(17):1775-1786.