scholarly journals Συγκριτική αξιολόγηση της ανάλυσης Fourier και της πολλαπλής γραμμικής παλινδρόμησης για τη μελέτη των χρονικών μεταβολών της πίεσης και της ροής κατά τη διάρκεια μηχανικής αναπνοής

2004 ◽  
Author(s):  
Αργυρώ Αμυγδάλου
Keyword(s):  
Respiratory System ◽  
Distress Syndrome ◽  
Respiratory Mechanics ◽  
Chronic Obstructive ◽  
Respiratory Disorder ◽  
Positive End Expiratory Pressure ◽  
Harmonic Content ◽  
Harmonic Term ◽  
Analytical Estimation ◽  
Chronic Obstructive Pulmonarydisease

Two linear methods for the analytical estimation of the respiratory system mechanicalparameters are compared the Multiple Linear Regression (MLR) and the Fourier Analysis(FA) This comparison refers to their competence and reliability during mechanical ventilationin 3 groups of patients a) without respiratory disorder b) with Chronic Obstructive PulmonaryDisease (COPD) and c) with acute respiratory distress syndrome (ARDS) Measurementswere applied in the usually applied range of ventilatory frequencies ((BF 0 17 0 33 Hz)externally applied positive end expiratory pressure (PEEP 0 10 hPa) Tidal volume (VT 300800 ml) before as well as after tracheotomy According to the results 1) The 2 methodsrevealed the differences of mechanical coefficients between the 3 studied groups of patientsElastance (Ers) Resistance (Rrs) Impedance (Zrs) Reactance (Xrs) phase angle betweenpressure and flow (Ors) time constant (Trs) and end expiratory pressure (EEP)) in allinstances accordingly 2) The two methods revealed clearly the influence of BF PEEP VTand tracheotomy on the mechanical parameters of the respiratory system 3) FA resultedgenerally to higher Ers Rrs Zrs Ors Trs and RMSD and to lower Xrs and EEP values thanMLR The higher differences between the 2 methods are noted in the ARDS & COPD groupsThis difference is influenced by the increase of BF PEEP and VTAlthough MLR depends on the total harmonic content of pressure & flow while FA is based onthe first harmonic term the two methods are equally reliable for revealing the underlyingpathophysiological respiratory disorder and the influence of BF PEEP VT and tracheotomyon the respiratory mechanics

scholarly journals Effects of Inhaled Fenoterol and Positive End-Expiratory Pressure on the Respiratory Mechanics of Patients with Chronic Obstructive Pulmonary Disease

2005 ◽  
Vol 12 (6) ◽  
pp. 329-335 ◽  
Author(s):  
Claude Guerin ◽  
Pierre-Guy Durand ◽  
Cécile Pereira ◽  
Jean-Christophe Richard ◽  
Jean-Charles Poupelin ◽  
...  
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Respiratory System ◽  
Lung Volume ◽  
Respiratory Mechanics ◽  
Chronic Obstructive ◽  
Flow Limitation ◽  
Total Resistance ◽  
Positive End Expiratory Pressure ◽  
Expiratory Flow Limitation ◽  
Obstructive Pulmonary Disease

BACKGROUND: During acute ventilatory failure in patients with chronic obstructive pulmonary disease (COPD), applying external positive end-expiratory pressure (PEEPe) will reopen small airways and, thus, may enhance peripheral deposition as well as the physiological effects of inhaled beta-2 agonists.OBJECTIVE: To investigate the efficacy of inhaled fenoterol applied by zero end-expiratory pressure (ZEEPe) or PEEPe.METHODS: Ten patients with COPD who were intubated and mechanically ventilated received fenoterol (10 mg/4 mL) via the ventilator using a jet nebulizer for 30 min on ZEEPe and PEEPe set at 80% of the total PEEP in a random order. The total resistance of the respiratory system (rapid airway occlusion technique), change in end-expiratory lung volume and expiratory flow limitation were assessed before and 5 min, 15 min, 30 min, 60 min and 240 min after fenoterol inhalation.RESULTS: Before inhalation and 60 min after inhalation, the total PEEP, the change in end-expiratory lung volume and the total resistance of the respiratory system were 8±3 cmH2O and 6±3 cmH2O, 0.61±0.34 L and 0.43±0.32 L, and 26±7 cmH2O/L/s and 23±6 cmH2O/L/s, respectively, with ZEEPe, and 9±3 cmH2O and 8±3 cmH2O (P<0.05 versus ZEEPe), 0.62±0.34 L and 0.62±0.37 L (P<0.05 versus ZEEPe), and 26±9 H2O/L/s and 25±9 H2O/L/s, respectively, with PEEPe. Three patients became not flow-limited under the combination of PEEPe and fenoterol.CONCLUSIONS: In patients with COPD, fenoterol combined with PEEPe has opposing effects on respiratory mechanics. First, it does not significantly reduce lung hyperinflation or inspiratory resistances. Second, it allows expiratory flow limitation reversal in some patients. These findings result from the net effect on end-expiratory lung volume of each intervention. This implies that if fenoterol is used in combination with PEEPe, the level of PEEPe should be reassessed during the time course of the drug to prevent any further lung hyperinflation.

Effect of PEEP on the mechanics of the respiratory system in ARDS patients

1992 ◽  
Vol 73 (5) ◽  
pp. 1728-1735 ◽  
Author(s):  
N. T. Eissa ◽  
V. M. Ranieri ◽  
C. Corbeil ◽  
M. Chasse ◽  
J. Braidy ◽  
...  
Keyword(s):  
Respiratory Distress Syndrome ◽  
Respiratory System ◽  
Distress Syndrome ◽  
Respiratory Mechanics ◽  
Constant Flow ◽  
Positive End Expiratory Pressure ◽  
Airway Occlusion ◽  
Additional Resistance ◽  
Respiratory Dynamics ◽  
Respiratory System Resistance

In patients with adult respiratory distress syndrome (ARDS) we studied the effect of positive end-expiratory pressure (PEEP) on respiratory mechanics. We used the technique of rapid airway occlusion during constant flow (V) inflation to partition the total respiratory system resistance (Rrs) into the interrupter resistance (Rint,rs) and the additional resistance (delta Rrs) due to viscoelastic pressure dissipations and time constant inequalities. We also measured static (Est,rs) and dynamic (Edyn,rs) elastance of the respiratory system. The procedure was carried out in nine ARDS patients at different inspiratory V and inflation volumes (delta V) at PEEP of 0, 5, 10, and 15 cmH2O. We found that during baseline ventilation (delta V = 0.7 liter and V = 1 l/s), Est,rs, Edyn,rs, and Rint,rs did not change significantly with PEEP, whereas delta Rrs and Rrs increased significantly only with PEEP of 15 cmH2O. The increase of delta Rrs and Rrs with PEEP was positively correlated with the concomitant changes in end-expiratory lung volume (P < 0.001). At all levels of PEEP, under iso-delta V conditions, delta Rrs decreased with increasing V, whereas at a fixed V, delta Rrs increased with increasing delta V. A four-parameter model of the respiratory system failed to fully describe respiratory dynamics in the ARDS patients, probably due to nonlinearities.

Respiratory Mechanics

2017 ◽  
Author(s):  
John W. Kreit
Keyword(s):  
Mechanical Ventilation ◽  
Respiratory System ◽  
Respiratory Mechanics ◽  
Pressure Change ◽  
Equation Of Motion ◽  
Positive End Expiratory Pressure ◽  
Elastic Recoil ◽  
Viscous Forces ◽  
Equilibrium Volume ◽  
Complex Process

Ventilation can occur only when the respiratory system expands above and then returns to its resting or equilibrium volume. This is just another way of saying that ventilation depends on our ability to breathe. Although breathing requires very little effort and even less thought, it’s nevertheless a fairly complex process. Respiratory Mechanics reviews the interaction between applied and opposing forces during spontaneous and mechanical ventilation. It discusses elastic recoil, viscous forces, compliance, resistance, and the equation of motion and the time constant of the respiratory system. It also describes how and why pleural, alveolar, lung transmural, intra-abdominal, and airway pressure change during spontaneous and mechanical ventilation, and the effect of applied positive end-expiratory pressure (PEEP).

scholarly journals Evaluation of Positive End-Expiratory Pressure Strategies in Patients With Coronavirus Disease 2019–Induced Acute Respiratory Distress Syndrome

2021 ◽  
Vol 8 ◽  
Author(s):  
Chun Pan ◽  
Cong Lu ◽  
Xiaobin She ◽  
Haibo Ren ◽  
Huazhang Wei ◽  
...  
Keyword(s):  
Acute Respiratory Distress Syndrome ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Distress Syndrome ◽  
Respiratory Mechanics ◽  
Plateau Pressure ◽  
Mechanical Power ◽  
Positive End Expiratory Pressure ◽  
The One ◽  
Compliance Strategy

Background: Different positive end-expiratory pressure (PEEP) strategies are available for subjects with coronavirus disease 2019 (COVID-19)–induced acute respiratory distress syndrome (ARDS) requiring invasive mechanical ventilation. We aimed to evaluate three conventional PEEP strategies on their effects on respiratory mechanics, gas exchanges, and hemodynamics.Methods: This is a prospective, physiologic, multicenter study conducted in China. We recruited 20 intubated subjects with ARDS and confirmed COVID-19. We first set PEEP by the ARDSnet low PEEP–fraction of inspired oxygen (FIO2) table. After a recruitment maneuver, PEEP was set at 15, 10, and 5 cm H2O for 10 min, respectively. Among these three PEEP levels, best-compliance PEEP was the one providing the highest respiratory system compliance; best-oxygenation PEEP was the one providing the highest PaO2 (partial pressure of arterial oxygen)/FIO2.Results: At each PEEP level, we assessed respiratory mechanics, arterial blood gas, and hemodynamics. Among three PEEP levels, plateau pressure, driving pressure, mechanical power, and blood pressure improved with lower PEEP. The ARDSnet low PEEP–FIO2 table and the best-oxygenation strategies provided higher PEEP than the best-compliance strategy (11 ± 6 cm H2O vs. 11 ± 3 cm H2O vs. 6 ± 2 cm H2O, p = 0.001), leading to higher plateau pressure, driving pressure, and mechanical power. The three PEEP strategies were not significantly different in gas exchange. The subgroup analysis showed that three PEEP strategies generated different effects in subjects with moderate or severe ARDS (n = 12) but not in subjects with mild ARDS (n = 8).Conclusions: In our cohort with COVID-19–induced ARDS, the ARDSnet low PEEP/FIO2 table and the best-oxygenation strategies led to higher PEEP and potentially higher risk of ventilator-induced lung injury than the best-compliance strategy.Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT04359251.

scholarly journals High-frequency oscillatory ventilation in neonatal RDS: initial volume optimization and respiratory mechanics

1998 ◽  
Vol 84 (4) ◽  
pp. 1174-1177 ◽  
Author(s):  
Masendu Kalenga ◽  
Oreste Battisti ◽  
Anne François ◽  
Jean-Paul Langhendries ◽  
Dale R. Gerstmann ◽  
...  
Keyword(s):  
Respiratory System ◽  
Lung Volume ◽  
High Frequency ◽  
Distress Syndrome ◽  
Respiratory Mechanics ◽  
High Frequency Oscillatory Ventilation ◽  
Oscillatory Ventilation ◽  
Respiratory System Resistance ◽  
High Frequency Oscillatory ◽  
Good Oxygenation

To determine whether initial lung volume optimization influences respiratory mechanics, which could indicate the achievement of optimal volume, we studied 17 premature infants with respiratory distress syndrome (RDS) assisted by high-frequency oscillatory ventilation. The continuous distending pressure (CDP) was increased stepwise from 6–8 cmH2O up to optimal CDP (OCDP), i.e., that allowing good oxygenation with the lowest inspired O2 fraction. Respiratory system compliance (Crs) and resistance were concomitantly measured. Mean OCDP was 16.5 ± 1.2 cmH2O. Inspired O2 fraction could be reduced from an initial level of 0.73 ± 0.17 to 0.33 ± 0.07. However, Crs (0.45 ± 0.14 ml ⋅ cmH2O−1 ⋅ kg−1at starting CDP point) remained unchanged through lung volume optimization but appeared inversely related to OCDP. Similarly, respiratory system resistance was not affected. We conclude that there is a marked dissociation between oxygenation improvement and Crs profile during the initial phase of lung recruitment by early high-frequency oscillatory ventilation in infants with RDS. Thus optimal lung volume cannot be defined by serial Crs measurement. At the most, low initial Crs suggests that higher CDP will be needed.

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