scholarly journals Tracking respiratory mechanics around natural breathing rates via variable ventilation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Samer Bou Jawde ◽  
Allan J. Walkey ◽  
Arnab Majumdar ◽  
George T. O’Connor ◽  
Bradford J. Smith ◽  
...  
Keyword(s):  
Respiratory Mechanics ◽  
Variable Ventilation ◽  
Natural Breathing

Biologically Variable Ventilation Improves Oxygenation and Respiratory Mechanics during One-lung Ventilation

2006 ◽  
Vol 105 (1) ◽  
pp. 91-97 ◽  
Author(s):  
Michael C. McMullen ◽  
Linda G. Girling ◽  
M Ruth Graham ◽  
W Alan C. Mutch
Keyword(s):  
Tidal Volume ◽  
Respiratory Mechanics ◽  
Lung Ventilation ◽  
Group Effect ◽  
Shunt Fraction ◽  
Static Compliance ◽  
One Lung Ventilation ◽  
Time Interaction ◽  
Variable Ventilation ◽  
Dead Space Ventilation

Background Hypoxemia is common during one-lung ventilation (OLV). Atelectasis contributes to the problem. Biologically variable ventilation (BVV), using microprocessors to reinstitute physiologic variability to respiratory rate and tidal volume, has been shown to be advantageous over conventional monotonous control mode ventilation (CMV) in improving oxygenation during the period of lung reinflation after OLV in an experimental model. Here, using a porcine model, the authors compared BVV with CMV during OLV to assess gas exchange and respiratory mechanics. Methods Eight pigs (25-30 kg) were studied in each of two groups. After induction of anesthesia-tidal volume 12 ml/kg with CMV and surgical intervention-tidal volume was reduced to 9 ml/kg. OLV was initiated with an endobronchial blocker, and the animals were randomly allocated to either continue CMV or switch to BVV for 90 min. After OLV, a recruitment maneuver was undertaken, and both lungs were ventilated for a further 60 min. At predetermined intervals, hemodynamics, respiratory gases (arterial, venous, and end-tidal samples) and mechanics (airway pressures, static and dynamic compliances) were measured. Derived indices (pulmonary vascular resistance, shunt fraction, and dead space ventilation) were calculated. Results By 15 min of OLV, arterial oxygen tension was greater in the BVV group (group x time interaction, P = 0.003), and shunt fraction was lower with BVV from 30 to 90 min (group effect, P = 0.0004). From 60 to 90 min, arterial carbon dioxide tension was lower with BVV (group x time interaction, P = 0.0001) and dead space ventilation was less from 60 to 90 min (group x time interaction, P = 0.0001). Static compliance was greater by 60 min of BVV and remained greater during return to ventilation of both lungs (group effect, P = 0.0001). Conclusions In this model of OLV, BVV resulted in superior gas exchange and respiratory mechanics when compared with CMV. Improved static compliance persisted with restoration of two-lung ventilation.

scholarly journals Benefit of Physiologically Variable Over Pressure-Controlled Ventilation in a Model of Chronic Obstructive Pulmonary Disease: A Randomized Study

2021 ◽  
Vol 11 ◽  
Author(s):  
Andre Dos Santos Rocha ◽  
Roberta Südy ◽  
Davide Bizzotto ◽  
Miklos Kassai ◽  
Tania Carvalho ◽  
...  
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Respiratory Mechanics ◽  
Chronic Obstructive ◽  
Shunt Fraction ◽  
Intrapulmonary Shunt ◽  
Obstructive Pulmonary Disease ◽  
Controlled Ventilation ◽  
Pressure Controlled Ventilation ◽  
Variable Ventilation ◽  
Pressure Controlled

IntroductionThe advantages of physiologically variable ventilation (PVV) based on a spontaneous breathing pattern have been demonstrated in several respiratory conditions. However, its potential benefits in chronic obstructive pulmonary disease (COPD) have not yet been characterized. We used an experimental model of COPD to compare respiratory function outcomes after 6 h of PVV versus conventional pressure-controlled ventilation (PCV).Materials and MethodsRabbits received nebulized elastase and lipopolysaccharide throughout 4 weeks. After 30 days, animals were anesthetized, tracheotomized, and randomized to receive 6 h of physiologically variable (n = 8) or conventional PCV (n = 7). Blood gases, respiratory mechanics, and chest fluoroscopy were assessed hourly.ResultsAfter 6 h of ventilation, animals receiving variable ventilation demonstrated significantly higher oxygenation index (PaO2/FiO2 441 ± 37 (mean ± standard deviation) versus 354 ± 61 mmHg, p < 0.001) and lower respiratory elastance (359 ± 36 versus 463 ± 81 cmH2O/L, p < 0.01) than animals receiving PCV. Animals ventilated with the variable mode also presented less lung derecruitment (decrease in lung aerated area, –3.4 ± 9.9 versus –17.9 ± 6.7%, p < 0.01) and intrapulmonary shunt fraction (9.6 ± 4.1 versus 17.0 ± 5.8%, p < 0.01).ConclusionPVV applied to a model of COPD improved oxygenation, respiratory mechanics, lung aeration, and intrapulmonary shunt fraction compared to conventional ventilation. A reduction in alveolar derecruitment and lung tissue stress leading to better aeration and gas exchange may explain the benefits of PVV.

Biologically variable ventilation improves gas exchange and respiratory mechanics in a model of severe bronchospasm*

2007 ◽  
Vol 35 (7) ◽  
pp. 1749-1755 ◽  
Author(s):  
W Alan C. Mutch ◽  
Timothy G. Buchman ◽  
Linda G. Girling ◽  
Elizabeth K-Y. Walker ◽  
Bruce M. McManus ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Respiratory Mechanics ◽  
Variable Ventilation

Design of a new variable-ventilation method optimized for lung recruitment in mice

2008 ◽  
Vol 104 (5) ◽  
pp. 1329-1340 ◽  
Author(s):  
Apiradee Thammanomai ◽  
Lauren E. Hueser ◽  
Arnab Majumdar ◽  
Erzsébet Bartolák-Suki ◽  
Béla Suki
Keyword(s):  
Lung Injury ◽  
Respiratory Mechanics ◽  
Dynamic Equilibrium ◽  
Blood Oxygenation ◽  
Lung Mechanics ◽  
Lung Collapse ◽  
Regional Lung ◽  
Variable Ventilation ◽  
Ventilation Modes ◽  
Ventilation Method

Variable ventilation (VV), characterized by breath-to-breath variation of tidal volume (Vt) and breathing rate (f), has been shown to improve lung mechanics and blood oxygenation during acute lung injury in many species compared with conventional ventilation (CV), characterized by constant Vt and f. During CV as well as VV, the lungs of mice tend to collapse over time; therefore, the goal of this study was to develop a new VV mode (VVN) with an optimized distribution of Vt to maximize recruitment. Groups of normal and HCl-injured mice were subjected to 1 h of CV, original VV (VVO), CV with periodic large breaths (CVLB), and VVN, and the effects of ventilation modes on respiratory mechanics, airway pressure, blood oxygenation, and IL-1β were assessed. During CV and VVO, normal and injured mice showed regional lung collapse with increased airway pressures and poor oxygenation. CVLB and VVN resulted in a stable dynamic equilibrium with significantly improved respiratory mechanics and oxygenation. Nevertheless, VVN provided a consistently better physiological response. In injured mice, VVO and VVN, but not CVLB, were able to reduce the IL-1β-related inflammatory response compared with CV. In conclusion, our results suggest that application of higher Vt values than the single Vt currently used in clinical situations helps stabilize lung function. In addition, variable stretch patterns delivered to the lung by VV can reduce the progression of lung injury due to ventilation in injured mice.

ENERGY ANALYSIS OF A NONLINEAR MODEL OF THE NORMAL HUMAN LUNG

2000 ◽  
Vol 08 (02) ◽  
pp. 115-139 ◽  
Author(s):  
A. ATHANASIADES ◽  
F. GHORBEL ◽  
J. W. CLARK ◽  
S. C. NIRANJAN ◽  
J. OLANSEN ◽  
...  
Keyword(s):  
Nonlinear Model ◽  
Respiratory Mechanics ◽  
Work Of Breathing ◽  
Laboratory Data ◽  
Upper Airways ◽  
Peripheral Airways ◽  
Viscoelastic Element ◽  
Wall Compliance ◽  
The Individual ◽  
Natural Breathing

Despite the existence of respiratory mechanics models in the literature, rarely one finds analytical expressions that predict the work of breathing (WOB) associated with natural breathing maneuvers in non-ventilated subjects. In the present study, we develop relations that explicitly identify WOB, based on a proposed nonlinear model of respiratory mechanics. The model partitions airways resistance into three components (upper, middle and small), includes a collapsible airways segment, a viscoelastic element describing lung tissue dynamics and a static chest wall compliance. The individual contribution of these respiratory components on WOB is identified and analyzed. For instance, according to model predictions, during the forced vital capacity (FVC) maneuver, most of the work is expended against dissipative forces, mainly during expiration. In addition, expiratory dissipative work during FVC is almost equally partitioned among the upper airways and the collapsible airways resistances. The former expends work at the beginning of expiration, the latter at the end of expiration. The contribution of the peripheral airways is small. Our predictions are validated against laboratory data collected from volunteer subjects and using the esophageal catheter balloon technique.

Auto-PEEP effects on respiratory mechanics and blood gases in mechanically ventilated patients

1998 ◽  
Vol 74 (4) ◽  
pp. 275-83
Author(s):  
Antônio C. P. Ferreira ◽  
Benjamin I. Kopelman ◽  
Werther Brunow de Carvalho ◽  
Jorge Bonassa
Keyword(s):  
Respiratory Mechanics ◽  
Blood Gases ◽  
Mechanically Ventilated ◽  
Mechanically Ventilated Patients ◽  
Ventilated Patients

scholarly journals Respiratory mechanics and gas exchanges in the early course of COVID-19 ARDS: a hypothesis-generating study

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
J.-L. Diehl ◽  
N. Peron ◽  
R. Chocron ◽  
B. Debuc ◽  
E. Guerot ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Dead Space ◽  
Respiratory Mechanics ◽  
Invasive Mechanical Ventilation ◽  
Endothelial Damage ◽  
Circulating Endothelial Cells ◽  
Pulmonary Mechanics ◽  
High Peep ◽  
Gas Exchanges ◽  
Physiological Dead Space

Abstract Rationale COVID-19 ARDS could differ from typical forms of the syndrome. Objective Pulmonary microvascular injury and thrombosis are increasingly reported as constitutive features of COVID-19 respiratory failure. Our aim was to study pulmonary mechanics and gas exchanges in COVID-2019 ARDS patients studied early after initiating protective invasive mechanical ventilation, seeking after corresponding pathophysiological and biological characteristics. Methods Between March 22 and March 30, 2020 respiratory mechanics, gas exchanges, circulating endothelial cells (CEC) as markers of endothelial damage, and D-dimers were studied in 22 moderate-to-severe COVID-19 ARDS patients, 1 [1–4] day after intubation (median [IQR]). Measurements and main results Thirteen moderate and 9 severe COVID-19 ARDS patients were studied after initiation of high PEEP protective mechanical ventilation. We observed moderately decreased respiratory system compliance: 39.5 [33.1–44.7] mL/cmH2O and end-expiratory lung volume: 2100 [1721–2434] mL. Gas exchanges were characterized by hypercapnia 55 [44–62] mmHg, high physiological dead-space (VD/VT): 75 [69–85.5] % and ventilatory ratio (VR): 2.9 [2.2–3.4]. VD/VT and VR were significantly correlated: r2 = 0.24, p = 0.014. No pulmonary embolism was suspected at the time of measurements. CECs and D-dimers were elevated as compared to normal values: 24 [12–46] cells per mL and 1483 [999–2217] ng/mL, respectively. Conclusions We observed early in the course of COVID-19 ARDS high VD/VT in association with biological markers of endothelial damage and thrombosis. High VD/VT can be explained by high PEEP settings and added instrumental dead space, with a possible associated role of COVID-19-triggered pulmonary microvascular endothelial damage and microthrombotic process.

Sign in / Sign up

Export Citation Format

Share Document