Dynamic hyperinflation and intrinsic PEEP in ARDS patients: who, when, and how needs more focus?

Dynamic hyperinflation and intrinsic PEEP almost always occur in patients with severe obstructive lung disease, in whom slowing of expiratory flow prevents complete exhalation. Occasionally, patients without airflow obstruction develop dynamic hyperinflation when expiratory time, is excessively shortened by a rapid respiratory rate, a long set inspiratory time (TI), or both. Dynamic Hyperinflation and Intrinsic Positive End-Expiratory Pressure describes the causes of dynamic hyperinflation and the mechanisms of its adverse effects, including reduced cardiac output and blood pressure, pulmonary barotrauma, and ineffective ventilator triggering. The chapter also describes how to screen for and measure intrinsic PEEP, and how to reduce or eliminate its adverse effects.

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Dynamic hyperinflation and intrinsic positive end-expiratory pressure in ARDS patients

Critical Care ◽

10.1186/s13054-019-2611-6 ◽

2019 ◽

Vol 23 (1) ◽

Cited By ~ 4

Author(s):

Silvia Coppola ◽

Alessio Caccioppola ◽

Sara Froio ◽

Erica Ferrari ◽

Miriam Gotti ◽

...

Keyword(s):

Mechanical Properties ◽

Tidal Volume ◽

Large Population ◽

Secondary Analysis ◽

Lung Protective Ventilation ◽

Intrinsic Peep ◽

Published Data ◽

Dynamic Hyperinflation ◽

Positive End Expiratory Pressure ◽

Predicted Body Weight

Abstract Background In ARDS patients, changes in respiratory mechanical properties and ventilatory settings can cause incomplete lung deflation at end-expiration. Both can promote dynamic hyperinflation and intrinsic positive end-expiratory pressure (PEEP). The aim of this study was to investigate, in a large population of ARDS patients, the presence of intrinsic PEEP, possible associated factors (patients’ characteristics and ventilator settings), and the effects of two different external PEEP levels on the intrinsic PEEP. Methods We made a secondary analysis of published data. Patients were ventilated with a tidal volume of 6–8 mL/kg of predicted body weight, sedated, and paralyzed. After a recruitment maneuver, a PEEP trial was run at 5 and 15 cmH2O, and partitioned mechanics measurements were collected after 20 min of stabilization. Lung computed tomography scans were taken at 5 and 45 cmH2O. Patients were classified into two groups according to whether or not they had intrinsic PEEP at the end of an expiratory pause. Results We enrolled 217 sedated, paralyzed patients: 87 (40%) had intrinsic PEEP with a median of 1.1 [1.0–2.3] cmH2O at 5 cmH2O of PEEP. The intrinsic PEEP significantly decreased with higher PEEP (1.1 [1.0–2.3] vs 0.6 [0.0–1.0] cmH2O; p < 0.001). The applied tidal volume was significantly lower (480 [430–540] vs 520 [445–600] mL at 5 cmH2O of PEEP; 480 [430–540] vs 510 [430–590] mL at 15 cmH2O) in patients with intrinsic PEEP, while the respiratory rate was significantly higher (18 [15–20] vs 15 [13–19] bpm at 5 cmH2O of PEEP; 18 [15–20] vs 15 [13–19] bpm at 15 cmH2O). At both PEEP levels, the total airway resistance and compliance of the respiratory system were not different in patients with and without intrinsic PEEP. The total lung gas volume and lung recruitability were also not different between patients with and without intrinsic PEEP (respectively 961 [701–1535] vs 973 [659–1433] mL and 15 [0–32] % vs 22 [0–36] %). Conclusions In sedated, paralyzed ARDS patients without a known obstructive disease, the amount of intrinsic PEEP during lung-protective ventilation is negligible and does not influence respiratory mechanical properties.

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Comparison of static and dynamic measurements of intrinsic PEEP in anesthetized cats

Journal of Applied Physiology ◽

10.1152/jappl.1994.76.6.2437 ◽

1994 ◽

Vol 76 (6) ◽

pp. 2437-2442 ◽

Cited By ~ 11

Author(s):

P. Hernandez ◽

P. Navalesi ◽

F. Maltais ◽

A. Gursahaney ◽

S. B. Gottfried

Keyword(s):

Mechanical Properties ◽

Airway Obstruction ◽

Time Constant ◽

Viscoelastic Behavior ◽

Intrinsic Peep ◽

Dynamic Hyperinflation ◽

Dynamic Measurements ◽

Pressure Losses ◽

The Difference ◽

Static Conditions

Dynamic measurements of intrinsic positive end-expiratory pressure (PEEPi,dyn) considerably underestimate values obtained under static conditions (PEEPi,stat) in patients with severe airway obstruction. This may be related to regional differences in respiratory system mechanical properties and/or viscoelastic behavior. To evaluate this concept, PEEPi,stat and PEEPi,dyn were compared in six anesthetized paralyzed cats during dynamic hyperinflation produced by inverse ratio ventilation (IRV) and aerosolized methacholine (MCh). PEEPi,stat did not differ between IRV and MCh, averaging 2.70 +/- 0.33 (SE) and 2.70 +/- 0.25 cmH2O, respectively. PEEPi,dyn was significantly less with MCh (0.25 +/- 0.05 cmH2O) than IRV (2.05 +/- 0.28 cmH2O) (P < 0.0001), resulting in a lower PEEPi,dyn/PEEPi,stat ratio for MCh (0.10 +/- 0.02) than for IRV (0.76 +/- 0.03) (P < 0.0001). Compared with control values (33.5 +/- 3.7 cmH2O.l-1.s), maximum resistance (Rmax) was unchanged during IRV (29.1 +/- 2.1 cmH2O.l-1.s) but increased considerably with MCh (288.8 +/- 18.4 cmH2O.l-1.s) (P < 0.0001). Similar changes in minimum resistance (Rmin) and delta R (Rmax-Rmin) were noted. There was a strong inverse relationship between delta P, an index of time constant inequalities and viscoelastic pressure losses and PEEPi,dyn/PEEPi,stat ratio. No correlation was found between this ratio and Rmax, Rmin, delta R, or compliance. In conclusion, PEEPi,dyn considerably underestimates PEEPi,stat in acute nonhomogeneous airway obstruction with MCh in contrast to IRV, where the magnitude and distribution of mechanical properties remain unaltered. These findings support the concept that the difference between PEEPi,dyn and PEEPi,stat is related to regional time constant inequalities and/or increased viscoelastic pressure losses.

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Dynamic Hyperinflation: Intrinsic Peep and its Ramifications in Patients with Respiratory Failure

Anesthesia and the Lung ◽

10.1007/978-94-009-0899-4_28 ◽

1989 ◽

pp. 261-268

Author(s):

J. Milic-Emili ◽

S. B. Gottfried ◽

A. Rossi

Keyword(s):

Respiratory Failure ◽

Intrinsic Peep ◽

Dynamic Hyperinflation

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Airway Occlusion Pressure to Titrate Positive End-expiratory Pressure in Patients with Dynamic Hyperinflation

Anesthesiology ◽

10.1097/00000542-200007000-00016 ◽

2000 ◽

Vol 93 (1) ◽

pp. 81-90 ◽

Cited By ~ 47

Author(s):

Jordi Mancebo ◽

Pierre Albaladejo ◽

Dominique Touchard ◽

Ela Bak ◽

Mireia Subirana ◽

...

Keyword(s):

Work Of Breathing ◽

Transpulmonary Pressure ◽

Assisted Ventilation ◽

Intrinsic Peep ◽

Chronic Obstructive ◽

Dynamic Hyperinflation ◽

Occlusion Pressure ◽

Positive End Expiratory Pressure ◽

Simple Method ◽

Obstructive Pulmonary Disease

Background Although the use of external positive end-expiratory pressure (PEEP) is recommended for patients with intrinsic PEEP, no simple method exists for bedside titration. We hypothesized that the occlusion pressure, measured from airway pressure during the phase of ventilator triggering (P0.1t), could help to indicate the effects of PEEP on the work of breathing (WOB). Methods Twenty patients under assisted ventilation with chronic obstructive pulmonary disease were studied with 0, 5, and 10 cm H2O of PEEP while ventilated with a fixed level of pressure support. Results PEEP 5 significantly reduced intrinsic PEEP (mean +/- SD, 5.2 +/- 2.4 cm H2O at PEEP 0 to 3.6 +/- 1.9 at PEEP 5; P < 0.001), WOB per min (12. 6 +/- 6.7 J/min to 9.1 +/- 5.9 J/min; P = 0.003), WOB per liter (1.2 +/- 0.4 J/l to 0.8 +/- 0.4 J/l; P < 0.001), pressure time product of the diaphragm (216 +/- 86 cm H2O. s-1. min-1 to 155 +/- 179 cm H2O. s-1. min-1; P = 0.001) and P0.1t (3.3 +/- 1.5 cm H2O to 2.3 +/- 1.4 cm H2O; P = 0.002). At PEEP 10, no further significant reduction in muscle effort nor in P0.1t (2.5 +/- 2.1 cm H2O) occurred, and transpulmonary pressure indicated an increase in end-expiratory lung volume. Significant correlations were found between WOB per min and P0.1t at the three levels of PEEP (P < 0.001), and between the changes in P0.1t versus the changes in WOB per min (P < 0.005), indicating that P0.1t and WOB changed in the same direction. A decrease in P0.1 with PEEP indicated a decrease in intrinsic PEEP with a specificity of 71% and a sensitivity of 88% and a decrease in WOB with a specificity of 86% and a sensitivity of 91%. Conclusion These results show that P0.1t may help to assess the effects of PEEP in patients with intrinsic PEEP.

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Physiological effects of adding ECCO2R to invasive mechanical ventilation for COPD exacerbations

Annals of Intensive Care ◽

10.1186/s13613-020-00743-y ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

J.-L. Diehl ◽

L. Piquilloud ◽

D. Vimpere ◽

N. Aissaoui ◽

E. Guerot ◽

...

Keyword(s):

Mechanical Ventilation ◽

Respiratory Rate ◽

Work Of Breathing ◽

Invasive Mechanical Ventilation ◽

Intrinsic Peep ◽

Dynamic Hyperinflation ◽

Copd Exacerbations ◽

Copd Patients ◽

Before And After ◽

Residual Capacity

Abstract Background Extracorporeal CO2 removal (ECCO2R) could be a valuable additional modality for invasive mechanical ventilation (IMV) in COPD patients suffering from severe acute exacerbation (AE). We aimed to evaluate in such patients the effects of a low-to-middle extracorporeal blood flow device on both gas exchanges and dynamic hyperinflation, as well as on work of breathing (WOB) during the IMV weaning process. Study design and methods Open prospective interventional study in 12 deeply sedated IMV AE-COPD patients studied before and after ECCO2R initiation. Gas exchange and dynamic hyperinflation were compared after stabilization without and with ECCO2R (Hemolung, Alung, Pittsburgh, USA) combined with a specific adjustment algorithm of the respiratory rate (RR) designed to improve arterial pH. When possible, WOB with and without ECCO2R was measured at the end of the weaning process. Due to study size, results are expressed as median (IQR) and a non-parametric approach was adopted. Results An improvement in PaCO2, from 68 (63; 76) to 49 (46; 55) mmHg, p = 0.0005, and in pH, from 7.25 (7.23; 7.29) to 7.35 (7.32; 7.40), p = 0.0005, was observed after ECCO2R initiation and adjustment of respiratory rate, while intrinsic PEEP and Functional Residual Capacity remained unchanged, from 9.0 (7.0; 10.0) to 8.0 (5.0; 9.0) cmH2O and from 3604 (2631; 4850) to 3338 (2633; 4848) mL, p = 0.1191 and p = 0.3013, respectively. WOB measurements were possible in 5 patients, indicating near-significant higher values after stopping ECCO2R: 11.7 (7.5; 15.0) versus 22.6 (13.9; 34.7) Joules/min., p = 0.0625 and 1.1 (0.8; 1.4) versus 1.5 (0.9; 2.8) Joules/L, p = 0.0625. Three patients died in-ICU. Other patients were successfully hospital-discharged. Conclusions Using a formalized protocol of RR adjustment, ECCO2R permitted to effectively improve pH and diminish PaCO2 at the early phase of IMV in 12 AE-COPD patients, but not to diminish dynamic hyperinflation in the whole group. A trend toward a decrease in WOB was also observed during the weaning process. Trial registration ClinicalTrials.gov: Identifier: NCT02586948.

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