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 < 0.04 comparing PEEP 15 and PEEP 0 cm H2O) and low external resistances (p < 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 < 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.

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.

Mechanical ventilation results in progressive contractile dysfunction in the diaphragm

2002 ◽  
Vol 92 (5) ◽  
pp. 1851-1858 ◽  
Author(s):  
Scott K. Powers ◽  
R. Andrew Shanely ◽  
Jeff S. Coombes ◽  
Thomas J. Koesterer ◽  
Michael McKenzie ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Spontaneous Breathing ◽  
Contractile Function ◽  
Control Group ◽  
Contractile Dysfunction ◽  
Sprague Dawley ◽  
Short Term ◽  
Mechanically Ventilated ◽  
Sprague Dawley Rats ◽  
Controlled Mechanical Ventilation

These experiments tested the hypothesis that a relatively short duration of controlled mechanical ventilation (MV) will impair diaphragmatic maximal specific force generation (specific Po) and that this force deficit will be exacerbated with increased time on the ventilator. To test this postulate, adult Sprague-Dawley rats were randomly divided into one of six experimental groups: 1) control ( n = 12); 2) 12 h of MV ( n = 4); 3) 18 h of MV ( n = 4); 4) 18 h of anesthesia and spontaneous breathing ( n = 4); 5) 24 h of MV ( n = 7); and 6) 24 h of anesthesia and spontaneous breathing ( n = 4). MV animals were anesthetized, tracheostomized, and ventilated with room air. Animals in the control group were acutely anesthetized but were not exposed to MV. Animals in two spontaneous breathing groups were anesthetized and breathed spontaneously for either 18 or 24 h. No differences ( P > 0.05) existed in diaphragmatic specific Po between control and the two spontaneous breathing groups. In contrast, compared with control, all durations of MV resulted in a reduction ( P < 0.05) in diaphragmatic specific tension at stimulation frequencies ranging from 15 to 160 Hz. Furthermore, the MV-induced decrease in diaphragmatic specific Po was time dependent, with specific Po being ∼18 and ∼46% lower ( P < 0.05) in animals mechanically ventilated for 12 and 24 h, respectively. These data support the hypothesis that relatively short-term MV impairs diaphragmatic contractile function and that the magnitude of MV-induced force deficit increases with time on the ventilator.

Pressure-controlled ventilation versus controlled mechanical ventilation with decelerating inspiratory flow

1993 ◽  
Vol 21 (8) ◽  
pp. 1143-1148 ◽  
Author(s):  
JAVIER MUÑOZ ◽  
JOSE EUGENIO GUERRERO ◽  
JOSE LUIS ESCALANTE ◽  
RICARDO PALOMINO ◽  
BRAULIO DE LA CALLE
Keyword(s):  
Mechanical Ventilation ◽  
Inspiratory Flow ◽  
Controlled Ventilation ◽  
Pressure Controlled Ventilation ◽  
Controlled Mechanical Ventilation ◽  
Pressure Controlled

Controversial Aspects of PEEP Ventilation in Emergency Medicine

1987 ◽  
Vol 3 (2) ◽  
pp. 21-27 ◽  
Author(s):  
W. Dick ◽  
I. Schutz
Keyword(s):  
Emergency Medicine ◽  
Mechanical Ventilation ◽  
Intensive Care ◽  
Clinical Treatment ◽  
Positive End Expiratory Pressure ◽  
Early Application ◽  
Therapeutic Measure ◽  
Controlled Mechanical Ventilation ◽  
Pulmonary Changes ◽  
Peep Ventilation

Controlled mechanical ventilation using positive and expiratory pressure (PEEP) is a well-established therapeutic measure in intensive care. Its early application has been shown to markedly decrease morbidity and mortality, especially in polytraumatized patients with an acute respiratory distresss syndrome. It therefore seems reasonable to use positive end expiratory pressure as early as possible in the clinical treatment of emergency patients before extensive pulmonary changes have had time to develop completely.

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 The use of pressure‐controlled mechanical ventilation in a swine model of intraoperative pediatric cardiac arrest

2020 ◽  
Vol 30 (4) ◽  
pp. 462-468
Author(s):  
Francis M. Lapid ◽  
Caitlin E. O'Brien ◽  
Sapna R. Kudchadkar ◽  
Jennifer K. Lee ◽  
Elizabeth A. Hunt ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Cardiac Arrest ◽  
Swine Model ◽  
Controlled Mechanical Ventilation ◽  
Pressure Controlled
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