Abstract
Background: The pressure-volume (P-V) curve has been suggested as a bedside tool to set mechanical ventilation; however, it reflects a global behavior of the lung without giving information on the regional mechanical properties. Regional P-V (PVr) curves derived from electrical impedance tomography (EIT) could provide valuable clinical information at bedside, being able to explore the regional mechanics of the lung. In the present study, we hypothesized that regional P-V curves would provide different information from those obtained from global P-V curves, both in terms of upper and lower inflection points. Therefore, we constructed pressure-volume curves for each pixel row from non-dependent to dependent lung regions of patients affected by acute hypoxemic respiratory failure (AHRF) and acute respiratory distress syndrome (ARDS). Methods: We analyzed slow-inflation P-V maneuvers data from 12 mechanically ventilated patients. During the inflation, the pneumotachograph was used to record flow and airway pressure while the EIT signals were recorded digitally. From each maneuver, global respiratory system P-V curve (PVg) and PVr curves were obtained, each one corresponding to a pixel row within the EIT image. PVg and PVr curves were fitted using a sigmoidal equation, and the upper (UIP) and lower (LIP) inflection points for each curve were mathematically identified; LIP and UIP from PVg were respectively called LIPg and UIPg. From each measurement, the highest regional LIP (LIPr MAX ) and the lowest regional UIP (UIPr MIN ) were identified and the pressure difference between those two points was defined as linear driving pressure (ΔP LIN ). Results: A significant difference (p < 0.001) was found between LIPr MAX (15.8 [9.2-21.1] cmH 2 O) and LIPg (2.9 [2.2-8.9] cmH 2 O); in all measurements, the LIPr MAX was higher than the corresponding LIPg. We found a significant difference (p < 0.005) between UIPr MIN (30.1 [23.5-37.6] cmH 2 O) and UIPg (40.5 [34.2-45] cmH 2 O), the UIPr MIN always being lower than the corresponding UIPg. Median ΔP LIN was 12.6 [7.4-20.8] cmH 2 O and in 56% of cases was < 14 cmH 2 O. Conclusions: Regional inflection points derived by EIT show high variability reflecting lung heterogeneity. Regional P-V curves obtained by EIT could convey more sensitive information than global lung mechanics on the pressures within which all lung regions express linear compliance. Trial registration: Clinicaltrials.gov, NCT02907840. Registered on 20 September 2016.
| Original language | English |
|---|---|
| Article number | 119 |
| Journal | Critical Care |
| Volume | 23 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Apr 16 2019 |
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Keywords
- Acute respiratory failure, acute respiratory distress syndrome
- Electrical impedance tomography
- Mechanical ventilation
- Personalized medicine
- Pressure-volume curve
ASJC Scopus subject areas
- Critical Care and Intensive Care Medicine
Cite this
Heterogeneity of regional inflection points from pressure-volume curves assessed by electrical impedance tomography. / Scaramuzzo, Gaetano; Spadaro, Savino; Waldmann, Andreas D.; Böhm, Stephan H.; Ragazzi, Riccardo; Marangoni, Elisabetta; Alvisi, Valentina; Spinelli, Elena; Mauri, Tommaso; Volta, Carlo Alberto.
In: Critical Care, Vol. 23, No. 1, 119, 16.04.2019.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Heterogeneity of regional inflection points from pressure-volume curves assessed by electrical impedance tomography
AU - Scaramuzzo, Gaetano
AU - Spadaro, Savino
AU - Waldmann, Andreas D.
AU - Böhm, Stephan H.
AU - Ragazzi, Riccardo
AU - Marangoni, Elisabetta
AU - Alvisi, Valentina
AU - Spinelli, Elena
AU - Mauri, Tommaso
AU - Volta, Carlo Alberto
PY - 2019/4/16
Y1 - 2019/4/16
N2 - Background: The pressure-volume (P-V) curve has been suggested as a bedside tool to set mechanical ventilation; however, it reflects a global behavior of the lung without giving information on the regional mechanical properties. Regional P-V (PVr) curves derived from electrical impedance tomography (EIT) could provide valuable clinical information at bedside, being able to explore the regional mechanics of the lung. In the present study, we hypothesized that regional P-V curves would provide different information from those obtained from global P-V curves, both in terms of upper and lower inflection points. Therefore, we constructed pressure-volume curves for each pixel row from non-dependent to dependent lung regions of patients affected by acute hypoxemic respiratory failure (AHRF) and acute respiratory distress syndrome (ARDS). Methods: We analyzed slow-inflation P-V maneuvers data from 12 mechanically ventilated patients. During the inflation, the pneumotachograph was used to record flow and airway pressure while the EIT signals were recorded digitally. From each maneuver, global respiratory system P-V curve (PVg) and PVr curves were obtained, each one corresponding to a pixel row within the EIT image. PVg and PVr curves were fitted using a sigmoidal equation, and the upper (UIP) and lower (LIP) inflection points for each curve were mathematically identified; LIP and UIP from PVg were respectively called LIPg and UIPg. From each measurement, the highest regional LIP (LIPr MAX ) and the lowest regional UIP (UIPr MIN ) were identified and the pressure difference between those two points was defined as linear driving pressure (ΔP LIN ). Results: A significant difference (p < 0.001) was found between LIPr MAX (15.8 [9.2-21.1] cmH 2 O) and LIPg (2.9 [2.2-8.9] cmH 2 O); in all measurements, the LIPr MAX was higher than the corresponding LIPg. We found a significant difference (p < 0.005) between UIPr MIN (30.1 [23.5-37.6] cmH 2 O) and UIPg (40.5 [34.2-45] cmH 2 O), the UIPr MIN always being lower than the corresponding UIPg. Median ΔP LIN was 12.6 [7.4-20.8] cmH 2 O and in 56% of cases was < 14 cmH 2 O. Conclusions: Regional inflection points derived by EIT show high variability reflecting lung heterogeneity. Regional P-V curves obtained by EIT could convey more sensitive information than global lung mechanics on the pressures within which all lung regions express linear compliance. Trial registration: Clinicaltrials.gov, NCT02907840. Registered on 20 September 2016.
AB - Background: The pressure-volume (P-V) curve has been suggested as a bedside tool to set mechanical ventilation; however, it reflects a global behavior of the lung without giving information on the regional mechanical properties. Regional P-V (PVr) curves derived from electrical impedance tomography (EIT) could provide valuable clinical information at bedside, being able to explore the regional mechanics of the lung. In the present study, we hypothesized that regional P-V curves would provide different information from those obtained from global P-V curves, both in terms of upper and lower inflection points. Therefore, we constructed pressure-volume curves for each pixel row from non-dependent to dependent lung regions of patients affected by acute hypoxemic respiratory failure (AHRF) and acute respiratory distress syndrome (ARDS). Methods: We analyzed slow-inflation P-V maneuvers data from 12 mechanically ventilated patients. During the inflation, the pneumotachograph was used to record flow and airway pressure while the EIT signals were recorded digitally. From each maneuver, global respiratory system P-V curve (PVg) and PVr curves were obtained, each one corresponding to a pixel row within the EIT image. PVg and PVr curves were fitted using a sigmoidal equation, and the upper (UIP) and lower (LIP) inflection points for each curve were mathematically identified; LIP and UIP from PVg were respectively called LIPg and UIPg. From each measurement, the highest regional LIP (LIPr MAX ) and the lowest regional UIP (UIPr MIN ) were identified and the pressure difference between those two points was defined as linear driving pressure (ΔP LIN ). Results: A significant difference (p < 0.001) was found between LIPr MAX (15.8 [9.2-21.1] cmH 2 O) and LIPg (2.9 [2.2-8.9] cmH 2 O); in all measurements, the LIPr MAX was higher than the corresponding LIPg. We found a significant difference (p < 0.005) between UIPr MIN (30.1 [23.5-37.6] cmH 2 O) and UIPg (40.5 [34.2-45] cmH 2 O), the UIPr MIN always being lower than the corresponding UIPg. Median ΔP LIN was 12.6 [7.4-20.8] cmH 2 O and in 56% of cases was < 14 cmH 2 O. Conclusions: Regional inflection points derived by EIT show high variability reflecting lung heterogeneity. Regional P-V curves obtained by EIT could convey more sensitive information than global lung mechanics on the pressures within which all lung regions express linear compliance. Trial registration: Clinicaltrials.gov, NCT02907840. Registered on 20 September 2016.
KW - Acute respiratory failure, acute respiratory distress syndrome
KW - Electrical impedance tomography
KW - Mechanical ventilation
KW - Personalized medicine
KW - Pressure-volume curve
UR - http://www.scopus.com/inward/record.url?scp=85064469208&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85064469208&partnerID=8YFLogxK
U2 - 10.1186/s13054-019-2417-6
DO - 10.1186/s13054-019-2417-6
M3 - Article
VL - 23
JO - Critical Care
JF - Critical Care
SN - 1466-609X
IS - 1
M1 - 119
ER -