Effective respiratory system elastance during positive-pressure breathing in supine man

1975 ◽  
Vol 39 (4) ◽  
pp. 541-547 ◽  
Author(s):  
W. T. Josenhans ◽  
T. A. Peacocke ◽  
G. Schaller
Keyword(s):  
Mechanical Ventilation ◽  
Respiratory System ◽  
Spontaneous Breathing ◽  
Lung Compliance ◽  
Abdominal Muscle ◽  
Positive Pressure ◽  
Passive Components ◽  
Mechanically Ventilated ◽  
Airway Opening ◽  
Healthy Males

Two healthy males relaxing supine on a ballistobed were mechanically ventilated at positive end-expiratory pressures (PEEP) from 0 to 19 cmH2O. Pressures at the airway opening, middle esophagus, and stomach were monitored, together with tidal volume (VT) and ballistobed displacement. The effective elastance (i.e., sum of active and passive components) of the respiratory system (E'rs) and its components--abdominal muscle (E'ab), diaphragm (E'di), and rib cage (E'rc)--were calculated. With increasing PEEP, lung compliance increased slightly, E'rc and E'di decreased linearly, and E'ab increased linearly. The combined effective elastance of abdomen and diaphragm (E'ab+di) first decreased and then increased again. The abdomen-diaphragm contribution to VT during mechanical ventilation was approximately half that of spontaneous breathing.

scholarly journals Energy transmission in mechanically ventilated children: a translational study

Critical Care ◽  
2020 ◽  
Vol 24 (1) ◽  
Author(s):  
Martin C. J. Kneyber ◽  
Stavroula Ilia ◽  
Alette A. Koopman ◽  
Patrick van Schelven ◽  
Jefta van Dijk ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Lung Injury ◽  
Endotracheal Tube ◽  
Respiratory System ◽  
Airway Resistance ◽  
Mechanical Energy ◽  
Laboratory Data ◽  
Lung Compliance ◽  
Lung Pathology ◽  
Mechanically Ventilated

Abstract Background Recurrent delivery of tidal mechanical energy (ME) inflicts ventilator-induced lung injury (VILI) when stress and strain exceed the limits of tissue tolerance. Mechanical power (MP) is the mathematical description of the ME delivered to the respiratory system over time. It is unknown how ME relates to underlying lung pathology and outcome in mechanically ventilated children. We therefore tested the hypothesis that ME per breath with tidal volume (Vt) normalized to bodyweight correlates with underlying lung pathology and to study the effect of resistance on the ME dissipated to the lung. Methods We analyzed routinely collected demographic, physiological, and laboratory data from deeply sedated and/or paralyzed children < 18 years with and without lung injury. Patients were stratified into respiratory system mechanic subgroups according to the Pediatric Mechanical Ventilation Consensus Conference (PEMVECC) definition. The association between MP, ME, lung pathology, and duration of mechanical ventilation as a primary outcome measure was analyzed adjusting for confounding variables and effect modifiers. The effect of endotracheal tube diameter (ETT) and airway resistance on energy dissipation to the lung was analyzed in a bench model with different lung compliance settings. Results Data of 312 patients with a median age of 7.8 (1.7–44.2) months was analyzed. Age (p <  0.001), RR p <  0.001), and Vt <  0.001) were independently associated with MPrs. ME but not MP correlated significantly (p <  0.001) better with lung pathology. Competing risk regression analysis adjusting for PRISM III 24 h score and PEMVECC stratification showed that ME on day 1 or day 2 of MV but not MP was independently associated with the duration of mechanical ventilation. About 33% of all energy generated by the ventilator was transferred to the lung and highly dependent on lung compliance and airway resistance but not on endotracheal tube size (ETT) during pressure control (PC) ventilation. Conclusions ME better related to underlying lung pathology and patient outcome than MP. The delivery of generated energy to the lung was not dependent on ETT size during PC ventilation. Further studies are needed to identify injurious MErs thresholds in ventilated children.

scholarly journals Inspiratory Efforts, Positive End-Expiratory Pressure, and External Resistances Influence Intraparenchymal Gas Redistribution in Mechanically Ventilated Injured Lungs

2021 ◽  
Vol 11 ◽  
Author(s):  
Mariangela Pellegrini ◽  
Göran Hedenstierna ◽  
Anders Sune Larsson ◽  
Gaetano Perchiazzi
Keyword(s):  
Mechanical Ventilation ◽  
Spontaneous Breathing ◽  
Distress Syndrome ◽  
Inspiratory Flow ◽  
High Peep ◽  
Swine Model ◽  
Positive End Expiratory Pressure ◽  
Mechanically Ventilated ◽  
Airway Opening ◽  
Controlled Mechanical Ventilation

BackgroundPotentially harmful lung overstretch can follow intraparenchymal gas redistribution during mechanical ventilation. We hypothesized that inspiratory efforts characterizing spontaneous breathing, positive end-expiratory pressure (PEEP), and high inspiratory resistances influence inspiratory intraparenchymal gas redistribution.MethodsThis was an experimental study conducted on a swine model of mild acute respiratory distress syndrome. Dynamic computed tomography and respiratory mechanics were simultaneously acquired at different PEEP levels and external resistances, during both spontaneous breathing and controlled mechanical ventilation. Images were collected at two cranial–caudal levels. Delta-volume images (ΔVOLs) were obtained subtracting pairs of consecutive inspiratory images. The first three ΔVOLs, acquired for each analyzed breath, were used for the analysis of inspiratory pendelluft defined as intraparenchymal gas redistribution before the start of inspiratory flow at the airway opening. The following ΔVOLs were used for the analysis of gas redistribution during ongoing inspiratory flow at the airway opening.ResultsDuring the first flow-independent phase of inspiration, the pendelluft of gas was observed only during spontaneous breathing and along the cranial-to-caudal and nondependent-to-dependent directions. The pendelluft was reduced by high PEEP (p &lt; 0.04 comparing PEEP 15 and PEEP 0 cm H2O) and low external resistances (p &lt; 0.04 comparing high and low external resistance). During the flow-dependent phase of inspiration, two patterns were identified: (1) gas displacing characterized by large gas redistribution areas; (2) gas scattering characterized by small, numerous areas of gas redistribution. Gas displacing was observed at low PEEP, high external resistances, and it characterized controlled mechanical ventilation (p &lt; 0.01, comparing high and low PEEP during controlled mechanical ventilation).ConclusionsLow PEEP and high external resistances favored inspiratory pendelluft. During the flow-dependent phase of the inspiration, controlled mechanical ventilation and low PEEP and high external resistances favored larger phenomena of intraparenchymal gas redistribution (gas displacing) endangering lung stability.

scholarly journals Estimation of change in pleural pressure in assisted and unassisted spontaneous breathing pediatric patients using fluctuation of central venous pressure: A preliminary study

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247360
Author(s):  
Nao Okuda ◽  
Miyako Kyogoku ◽  
Yu Inata ◽  
Kanako Isaka ◽  
Kazue Moon ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Spontaneous Breathing ◽  
Pediatric Patients ◽  
Venous Pressure ◽  
Balloon Catheter ◽  
Pleural Pressure ◽  
Respiratory Effort ◽  
Central Venous ◽  
Mechanically Ventilated ◽  
Esophageal Balloon

Background It is important to evaluate the size of respiratory effort to prevent patient self-inflicted lung injury and ventilator-induced diaphragmatic dysfunction. Esophageal pressure (Pes) measurement is the gold standard for estimating respiratory effort, but it is complicated by technical issues. We previously reported that a change in pleural pressure (ΔPpl) could be estimated without measuring Pes using change in CVP (ΔCVP) that has been adjusted with a simple correction among mechanically ventilated, paralyzed pediatric patients. This study aimed to determine whether our method can be used to estimate ΔPpl in assisted and unassisted spontaneous breathing patients during mechanical ventilation. Methods The study included hemodynamically stable children (aged <18 years) who were mechanically ventilated, had spontaneous breathing, and had a central venous catheter and esophageal balloon catheter in place. We measured the change in Pes (ΔPes), ΔCVP, and ΔPpl that was calculated using a corrected ΔCVP (cΔCVP-derived ΔPpl) under three pressure support levels (10, 5, and 0 cmH2O). The cΔCVP-derived ΔPpl value was calculated as follows: cΔCVP-derived ΔPpl = k × ΔCVP, where k was the ratio of the change in airway pressure (ΔPaw) to the ΔCVP during airway occlusion test. Results Of the 14 patients enrolled in the study, 6 were excluded because correct positioning of the esophageal balloon could not be confirmed, leaving eight patients for analysis (mean age, 4.8 months). Three variables that reflected ΔPpl (ΔPes, ΔCVP, and cΔCVP-derived ΔPpl) were measured and yielded the following results: -6.7 ± 4.8, − -2.6 ± 1.4, and − -7.3 ± 4.5 cmH2O, respectively. The repeated measures correlation between cΔCVP-derived ΔPpl and ΔPes showed that cΔCVP-derived ΔPpl had good correlation with ΔPes (r = 0.84, p< 0.0001). Conclusions ΔPpl can be estimated reasonably accurately by ΔCVP using our method in assisted and unassisted spontaneous breathing children during mechanical ventilation.

scholarly journals Spontaneous Breathing or Mechanical Ventilation Alters Lung Compliance and Tissue Association of Exogenous Surfactant in Preterm Newborn Rabbits

2005 ◽  
Vol 57 (5 Part 1) ◽  
pp. 624-630 ◽  
Author(s):  
Kajsa Bohlin ◽  
Rabea K L Bouhafs ◽  
Connie Jarstrand ◽  
Tore Curstedt ◽  
Mats Blennow ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Spontaneous Breathing ◽  
Lung Compliance ◽  
Exogenous Surfactant ◽  
Preterm Newborn

scholarly journals Immediate effects of manual hyperinflation on cardiorespiratory function and sputum clearance in mechanically ventilated pediatric patients: A randomized crossover trial

2021 ◽  
pp. 1-8
Author(s):  
Tawatchai Luadsri ◽  
Jaturon Boonpitak ◽  
Kultida Pongdech-Udom ◽  
Patnuch Sukpom ◽  
Weerapong Chidnok
Keyword(s):  
Blood Pressure ◽  
Mechanical Ventilation ◽  
Critical Care ◽  
Pediatric Patients ◽  
Physical Therapist ◽  
Peak Inspiratory Pressure ◽  
Lung Compliance ◽  
Post Intervention ◽  
Mechanically Ventilated ◽  
Arterial Blood

Background: In developing countries, lower respiratory tract infection is a major cause of death in children, with severely ill patients being admitted to the critical-care unit. While physical therapists commonly use the manual hyperinflation (MHI) technique for secretion mass clearance in critical-care patients, its efficacy has not been determined in pediatric patients. Objective:This study investigated the effects of MHI on secretion mass clearance and cardiorespiratory responses in pediatric patients undergoing mechanical ventilation. Methods:A total of 12 intubated and mechanically ventilated pediatric patients were included in this study. At the same time of the day, the patients received two randomly ordered physical therapy treatments (MHI with suction and suction alone) from a trained physical therapist, with a washout period of 4[Formula: see text]h provided between interventions. Results:The MHI treatment increased the tidal volume [[Formula: see text]; 1.2[Formula: see text]mL/kg (95% CI, 0.8–1.5)] and static lung compliance [[Formula: see text]; 3.7[Formula: see text]mL/cmH2O (95% CI, 2.6–4.8)] immediately post-intervention compared with the baseline ([Formula: see text]). Moreover, the MHI with suction induced higher [Formula: see text] [1.4[Formula: see text]mL/kg (95% CI, 0.8–2.1)] and [Formula: see text] [3.4[Formula: see text]mL/cmH2O (95% CI, 2.1–4.7)] compared with the suction-alone intervention. In addition, the secretion mass [0.7[Formula: see text]g (95% CI, 0.6–0.8)] was greater in MHI with suction compared with suction alone ([Formula: see text]). However, there was no difference in peak inspiratory pressure, mean airway pressure, respiratory rate, heart rate, blood pressure, mean arterial blood pressure or oxygen saturation ([Formula: see text]) between interventions. Conclusions:MHI can improve [Formula: see text], [Formula: see text] and secretion mass without inducing adverse hemodynamic effects upon the pediatric patients requiring mechanical ventilation.

scholarly journals Mechanical power normalized to lung-thorax compliance indicates weaning readiness in prolonged ventilated patients

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Alessandro Ghiani ◽  
Joanna Paderewska ◽  
Swenja Walcher ◽  
Konstantinos Tsitouras ◽  
Claus Neurohr ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Logistic Regression ◽  
Respiratory System ◽  
Spontaneous Breathing ◽  
Characteristic Curve ◽  
Spontaneous Breathing Trial ◽  
Mechanical Power ◽  
Binary Logistic Regression Model ◽  
Weaning Failure ◽  
Ventilated Patients

AbstractSince critical respiratory muscle workload is a significant determinant of weaning failure, applied mechanical power (MP) during artificial ventilation may serve for readiness testing before proceeding on a spontaneous breathing trial (SBT). Secondary analysis of a prospective, observational study in 130 prolonged ventilated, tracheotomized patients. Calculated MP’s predictive SBT outcome performance was determined using the area under receiver operating characteristic curve (AUROC), measures derived from k-fold cross-validation (likelihood ratios, Matthew's correlation coefficient [MCC]), and a multivariable binary logistic regression model. Thirty (23.1%) patients failed the SBT, with absolute MP presenting poor discriminatory ability (MCC 0.26; AUROC 0.68, 95%CI [0.59‒0.75], p = 0.002), considerably improved when normalized to lung-thorax compliance (LTCdyn-MP, MCC 0.37; AUROC 0.76, 95%CI [0.68‒0.83], p < 0.001) and mechanical ventilation PaCO2 (so-called power index of the respiratory system [PIrs]: MCC 0.42; AUROC 0.81 [0.73‒0.87], p < 0.001). In the logistic regression analysis, PIrs (OR 1.48 per 1000 cmH2O2/min, 95%CI [1.24‒1.76], p < 0.001) and its components LTCdyn-MP (1.25 per 1000 cmH2O2/min, [1.06‒1.46], p < 0.001) and mechanical ventilation PaCO2 (1.17 [1.06‒1.28], p < 0.001) were independently related to SBT failure. MP normalized to respiratory system compliance may help identify prolonged mechanically ventilated patients ready for spontaneous breathing.

Lung Ventilation: Natural and Mechanical

2017 ◽  
Author(s):  
Yuan Lei
Keyword(s):  
Mechanical Ventilation ◽  
Critical Care ◽  
Respiratory System ◽  
Positive Pressure Ventilation ◽  
Lung Ventilation ◽  
Intermittent Positive Pressure Ventilation ◽  
Artificial Lung ◽  
Positive Pressure ◽  
Anatomy And Physiology ◽  
Artificial Lung Ventilation

‘Lung Ventilation: Natural and Mechanical’ describes the processes of respiration and lung ventilation, focusing on those issues related directly to mechanical ventilation. The chapter starts by discussing the anatomy and physiology of respiration, and the involvement of the lungs and the entire respiratory system. It continues by introducing the three operating principles of mechanical ventilation. It then narrows its focus to intermittent positive pressure ventilation (IPPV), the operating principle of most modern critical care ventilators, explaining the pneumatic process of IPPV. The chapter ends by comparing natural and mechanical/artificial lung ventilation.

scholarly journals The Extent of Ventilator-Induced Lung Injury in Mice Partly Depends on Duration of Mechanical Ventilation

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Maria A. Hegeman ◽  
Sabrine N. T. Hemmes ◽  
Maria T. Kuipers ◽  
Lieuwe D. J. Bos ◽  
Geartsje Jongsma ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Lung Injury ◽  
Capillary Permeability ◽  
Statistical Significance ◽  
Lung Compliance ◽  
Alveolar Cell ◽  
Mechanically Ventilated ◽  
Ventilator Induced Lung Injury ◽  
Cell Counts ◽  
Alveolar Capillary

Background. Mechanical ventilation (MV) has the potential to initiate ventilator-induced lung injury (VILI). The pathogenesis of VILI has been primarily studied in animal models using more or less injurious ventilator settings. However, we speculate that duration of MV also influences severity and character of VILI.Methods. Sixty-four healthy C57Bl/6 mice were mechanically ventilated for 5 or 12 hours, using lower tidal volumes with positive end-expiratory pressure (PEEP) or higher tidal volumes without PEEP. Fifteen nonventilated mice served as controls.Results. All animals remained hemodynamically stable and survived MV protocols. In both MV groups, PaO2to FiO2ratios were lower and alveolar cell counts were higher after 12 hours of MV compared to 5 hours. Alveolar-capillary permeability was increased after 12 hours compared to 5 hours, although differences did not reach statistical significance. Lung levels of inflammatory mediators did not further increase over time. Only in mice ventilated with increased strain, lung compliance declined and wet to dry ratio increased after 12 hours of MV compared to 5 hours.Conclusions. Deleterious effects of MV are partly dependent on its duration. Even lower tidal volumes with PEEP may initiate aspects of VILI after 12 hours of MV.

Persistent bronchiolar remodeling following brief ventilation of the very immature ovine lung

2009 ◽  
Vol 297 (5) ◽  
pp. L992-L1001 ◽  
Author(s):  
Megan O'Reilly ◽  
Stuart B. Hooper ◽  
Beth J. Allison ◽  
Sharon J. Flecknoe ◽  
Ken Snibson ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Lung Function ◽  
Peak Inspiratory Pressure ◽  
Positive Pressure ◽  
Small Airways ◽  
Proliferating Cells ◽  
Fetal Sheep ◽  
Epithelial Injury ◽  
Mechanically Ventilated ◽  
Increased Risk

Children and adults who were mechanically ventilated following preterm birth are at increased risk of reduced lung function, suggesting small airway dysfunction. We hypothesized that short periods of mechanical ventilation of very immature lungs can induce persistent bronchiolar remodeling that may adversely affect later lung function. Our objectives were to characterize the effects of brief, positive-pressure ventilation per se on the small airways in very immature, surfactant-deficient lungs and to determine whether the effects persist after the cessation of ventilation. Fetal sheep (0.75 of term) were mechanically ventilated in utero with room air (peak inspiratory pressure 40 cmH2O, positive end-expiratory pressure 4 cmH2O, 65 breaths/min) for 6 or 12 h, after which tissues were collected; another group was studied 7 days after 12-h ventilation. Age-matched unventilated fetuses were controls. The mean basement membrane perimeter of airways analyzed was 548.6 ± 8.5 μm and was not different between groups. Immediately after ventilation, 21% of airways had epithelial injury; in airways with intact epithelium, there was more airway smooth muscle (ASM) and less collagen, and the epithelium contained more mucin-containing and apoptotic cells and fewer proliferating cells. Seven days after ventilation, epithelial injury was absent but the epithelium was thicker, with greater cell turnover; there were increased amounts of bronchiolar collagen and ASM and fewer alveolar attachments. The increase in ASM was likely due to cellular hypertrophy rather than hyperplasia. We conclude that brief mechanical ventilation of the very immature lung induces remodeling of the bronchiolar epithelium and walls that lasts for at least 7 days; such changes could contribute to later airway dysfunction.

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