Lung regional stress and strain as a function of posture and ventilatory mode

During positive-pressure ventilation parenchymal deformation can be assessed as strain (volume increase above functional residual capacity) in response to stress (transpulmonary pressure). The aim of this study was to explore the relationship between stress and strain on the regional level using computed tomography in anesthetized healthy pigs in two postures and two patterns of breathing. Airway opening and esophageal pressures were used to calculate stress; change of gas content as assessed from computed tomography was used to calculate strain. Static stress-strain curves and dynamic strain-time curves were constructed, the latter during the inspiratory phase of volume and pressure-controlled ventilation, both in supine and prone position. The lung was divided into nondependent, intermediate, dependent, and central regions: their curves were modeled by exponential regression and examined for statistically significant differences. In all the examined regions, there were strong but different exponential relations between stress and strain. During mechanical ventilation, the end-inspiratory strain was higher in the dependent than in the nondependent regions. No differences between volume- and pressure-controlled ventilation were found. However, during volume control ventilation, prone positioning decreased the end-inspiratory strain of dependent regions and increased it in nondependent regions, resulting in reduced strain gradient. Strain is inhomogeneously distributed within the healthy lung. Prone positioning attenuates differences between dependent and nondependent regions. The regional effects of ventilatory mode and body positioning should be further explored in patients with acute lung injury.

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Effect of mechanical pressure-controlled ventilation in patients with disturbed respiratory function during laparoscopic cholecystectomy

Vojnosanitetski pregled ◽

10.2298/vsp1301009s ◽

2013 ◽

Vol 70 (1) ◽

pp. 9-15

Author(s):

Maja Surbatovic ◽

Zoran Vesic ◽

Dragan Djordjevic ◽

Sonja Radakovic ◽

Snjezana Zeba ◽

...

Keyword(s):

Laparoscopic Cholecystectomy ◽

Respiratory Function ◽

Respiratory Diseases ◽

Positive Pressure ◽

Time Interval ◽

Time Intervals ◽

Controlled Ventilation ◽

Arterial Blood ◽

Pressure Controlled Ventilation ◽

Pressure Controlled

Background/Aim: Laparoscopic cholecystectomy is considered to be the gold standard for laparoscopic surgical procedures. In ASA III patients with concomitant respiratory diseases, however, creation of pneumoperitoneum and the position of patients during surgery exert additional negative effect on intraoperative respiratory function, thus making a higher challenge for the anesthesiologist than for the surgeon. The aim of this study was to compare the effect of intermittent positive pressure ventilation (IPPV) and pressure controlled ventilation (PCV) during general anesthesia on respiratory function in ASA III patients submitted to laparoscopic cholecystectomy. Methods. The study included 60 patients randomized into two groups depending on the mode of ventilation: IPPV or PCV. Respiratory volume (VT), peak inspiratory pressure (PIP), compliance (C), end-tidal CO2 pressure (PETCO2), oxygen saturation (SpO2), partial pressures of O2, CO2 (PaO2 and PaCO2) and pH of arterial blood were recorded within four time intervals. Results. There were no statistically significant differences in VT, SpO2, PaO2, PaCO2 and pH values neither within nor between the two groups. In time interval t1 there were no statistically significant differences in PIP, C, PETCO2 values between the IPPV and the PCV group. But, in the next three time intervals there was a difference in PIP, C, and PETCO2 values between the two groups which ranged from statistically significant to highly significant; PIP was lower, C and PETCO2 were higher in the PCV group. Conclusion. Pressure controlled ventilation better maintains stability regarding intraoperative ventilatory parameters in ASA III patients with concomitant respiratory diseases during laparoscopic cholecystectomy.

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Effects of nitrous oxide on cardiovascular parameters in pigs anesthetized with propofol and subjected to pressure-controlled ventilation

Semina Ciências Agrárias ◽

10.5433/1679-0359.2017v38n4p2209 ◽

2017 ◽

Vol 38 (4) ◽

pp. 2209

Author(s):

Rodrigo Lima Carneiro ◽

Patrícia Cristina Ferro Lopes ◽

Ana Paula Gering ◽

Eliselle Gouveia de Faria Biteli ◽

Paloma Do Espírito Santo Silva ◽

...

Keyword(s):

Nitrous Oxide ◽

Resistance Index ◽

Compressed Air ◽

Positive Pressure ◽

Stroke Index ◽

Cardiovascular Parameters ◽

Controlled Ventilation ◽

Pressure Controlled Ventilation ◽

Bonferroni Test ◽

Pressure Controlled

This paper evaluated the effects of the ratio of nitrous oxide to oxygen (50% of each) on cardiovascular parameters in pigs anesthetized with propofol and maintained in ventilation with intermittent positive pressure. Sixteen Large White pigs, weighing between 15 and 20 kg, were divided into two groups of eight animals, and designated as follows: GPN (propofol/nitrous oxide) and GPA (propofol/compressed air). In order to allow endotracheal intubation, the animals received azaperone (2 mg kg-1, IM) followed, after 20 minutes, by intravenous propofol. After successful intubation, continuous infusion of propofol was initiated at a dose of 0.4 mg kg-1minute-1. From this point, the GPN group received N2O (diluted in 50% oxygen), while the GPA group received compressed air (diluted in 50% oxygen). Rocuronium was then administered by continuous intravenous infusion at 0.6 mg kg-1h-1. Pressure-controlled ventilation (PCV) was started and adjusted to 15 cmH2O, and the respiratory rate was set to reach capnometry readings between 35-45 mmHg. The measurement of parameters (heart rate, mean arterial pressure, cardiac index, systemic vascular resistance index, stroke index) begun 15 minutes after the administration of rocuronium, and was repeated in 15-minute intervals for 60 minutes. Data were statistically analyzed by ANOVA followed by Bonferroni test. The results showed that the 1:1 ratio combination of nitrous oxide to oxygen (50% each) did not alter the mentioned parameters in pigs anesthetized with propofol and maintained at pressure-controlled ventilation, indicating that it is a safe protocol for the cardiovascular system.

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Effects on Lung Gas Volume, Respiratory Mechanics and Gas Exchange of a Closed-Circuit Suctioning System during Volume- and Pressure-Controlled Ventilation in ARDS Patients

Journal of Clinical Medicine ◽

10.3390/jcm10235657 ◽

2021 ◽

Vol 10 (23) ◽

pp. 5657

Author(s):

Davide Chiumello ◽

Luca Bolgiaghi ◽

Paolo Formenti ◽

Tommaso Pozzi ◽

Manuela Lucenteforte ◽

...

Keyword(s):

Gas Exchange ◽

Respiratory Mechanics ◽

Pressure Control ◽

Closed Circuit ◽

Volume Control ◽

Endotracheal Suctioning ◽

Controlled Ventilation ◽

Pressure Controlled Ventilation ◽

Gas Volume ◽

Pressure Controlled

Mechanically ventilated patients periodically require endotracheal suctioning. There are conflicting data regarding the loss of lung gas volume caused by the application of a negative pressure by closed-circuit suctioning. The aim of this study was to evaluate the effects of suctioning performed by a closed-circuit system in ARDS patients during volume- or pressure-controlled ventilation. In this prospective crossover-design study, 18 ARDS patients were ventilated under volume and pressure control applied in random order. Gas exchange, respiratory mechanics and EIT-derived end-expiratory lung volume (EELV) before the suctioning manoeuvre and after 5, 15 and 30 min were recorded. The tidal volume and respiratory rate were similar in both ventilation modes; in volume control, the EELV decreased by 31 ± 23 mL, 5 min after the suctioning, but it remained similar after 15 and 30 min; the oxygenation, PaCO2 and respiratory system elastance did not change. In the pressure control, 5 min after suctioning, EELV decreased by 35 (26–46) mL, the PaO2/FiO2 did not change, while PaCO2 increased by 5 and 30 min after suctioning (45 (40–51) vs. 48 (43–52) and 47 (42–54) mmHg, respectively). Our results suggest minimal clinical advantages when a closed system is used in volume-controlled compared to pressure-controlled ventilation.

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Physiologically variable ventilation reduces regional lung inflammation in a pediatric model of acute respiratory distress syndrome

Respiratory Research ◽

10.1186/s12931-020-01559-x ◽

2020 ◽

Vol 21 (1) ◽

Author(s):

Andre Dos Santos Rocha ◽

Gergely H. Fodor ◽

Miklos Kassai ◽

Loic Degrugilliers ◽

Sam Bayat ◽

...

Keyword(s):

Computed Tomography ◽

Mechanical Ventilation ◽

Acute Respiratory Distress Syndrome ◽

Lung Inflammation ◽

Distress Syndrome ◽

Controlled Ventilation ◽

Pressure Controlled Ventilation ◽

Regional Lung ◽

Variable Ventilation ◽

Pressure Controlled

Abstract Background Benefits of variable mechanical ventilation based on the physiological breathing pattern have been observed both in healthy and injured lungs. These benefits have not been characterized in pediatric models and the effect of this ventilation mode on regional distribution of lung inflammation also remains controversial. Here, we compare structural, molecular and functional outcomes reflecting regional inflammation between PVV and conventional pressure-controlled ventilation (PCV) in a pediatric model of healthy lungs and acute respiratory distress syndrome (ARDS). Methods New-Zealand White rabbit pups (n = 36, 670 ± 20 g [half-width 95% confidence interval]), with healthy lungs or after induction of ARDS, were randomized to five hours of mechanical ventilation with PCV or PVV. Regional lung aeration, inflammation and perfusion were assessed using x-ray computed tomography, positron-emission tomography and single-photon emission computed tomography, respectively. Ventilation parameters, blood gases and respiratory tissue elastance were recorded hourly. Results Mechanical ventilation worsened respiratory elastance in healthy and ARDS animals ventilated with PCV (11 ± 8%, 6 ± 3%, p < 0.04), however, this trend was improved by PVV (1 ± 4%, − 6 ± 2%). Animals receiving PVV presented reduced inflammation as assessed by lung normalized [18F]fluorodeoxyglucose uptake in healthy (1.49 ± 0.62 standardized uptake value, SUV) and ARDS animals (1.86 ± 0.47 SUV) compared to PCV (2.33 ± 0.775 and 2.28 ± 0.3 SUV, respectively, p < 0.05), particularly in the well and poorly aerated lung zones. No benefit of PVV could be detected on regional blood perfusion or blood gas parameters. Conclusions Variable ventilation based on a physiological respiratory pattern, compared to conventional pressure-controlled ventilation, reduced global and regional inflammation in both healthy and injured lungs of juvenile rabbits.

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Effect of Ventilatory Settings on Accuracy of Cardiac Output Measurement Using Partial CO2Rebreathing

Anesthesiology ◽

10.1097/00000542-200201000-00021 ◽

2002 ◽

Vol 96 (1) ◽

pp. 96-102 ◽

Cited By ~ 40

Author(s):

Kazuya Tachibana ◽

Hideaki Imanaka ◽

Hiroshi Miyano ◽

Muneyuki Takeuchi ◽

Keiji Kumon ◽

...

Keyword(s):

Cardiac Output ◽

Tidal Volume ◽

Positive End Expiratory Pressure ◽

Limits Of Agreement ◽

Ventilatory Mode ◽

Controlled Ventilation ◽

Pressure Controlled Ventilation ◽

Volume Controlled Ventilation ◽

Volume Controlled ◽

Pressure Controlled

Background Recently, a new device has been developed to measure cardiac output noninvasively using partial carbon dioxide (CO(2)) rebreathing. Because this technique uses CO(2) rebreathing, the authors suspected that ventilatory settings, such as tidal volume and ventilatory mode, would affect its accuracy: they conducted this study to investigate which parameters affect the accuracy of the measurement. Methods The authors enrolled 25 pharmacologically paralyzed adult post-cardiac surgery patients. They applied six ventilatory settings in random order: (1) volume-controlled ventilation with inspired tidal volume (V(T)) of 12 ml/kg; (2) volume-controlled ventilation with V(T) of 6 ml/kg; (3) pressure-controlled ventilation with V(T) of 12 ml/kg; (4) pressure-controlled ventilation with V(T) of 6 ml/kg; (5) inspired oxygen fraction of 1.0; and (6) high positive end-expiratory pressure. Then, they changed the maximum or minimum length of rebreathing loop with V(T) set at 12 ml/kg. After establishing steady-state conditions (15 min), they measured cardiac output using CO(2) rebreathing and thermodilution via a pulmonary artery catheter. Finally, they repeated the measurements during pressure support ventilation, when the patients had restored spontaneous breathing. The correlation between two methods was evaluated with linear regression and Bland-Altman analysis. Results When VT was set at 12 ml/kg, cardiac output with the CO(2) rebreathing technique correlated moderately with that measured by thermodilution (y = 1.02x, R = 0.63; bias, 0.28 l/min; limits of agreement, -1.78 to +2.34 l/min), regardless of ventilatory mode, oxygen concentration, or positive end-expiratory pressure. However, at a lower VT of 6 ml/kg, the CO(2) rebreathing technique underestimated cardiac out-put compared with thermodilution (y = 0.70x; R = 0.70; bias, -1.66 l/min; limits of agreement, -3.90 to +0.58 l/min). When the loop was fully retracted, the CO(2) rebreathing technique overestimated cardiac output. Conclusions Although cardiac output was underreported at small VT values, cardiac output measured by the CO(2) rebreathing technique correlates fairly with that measured by the thermodilution method.

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Efficiency of the newly introduced ventilatory mode “pressure controlled ventilation-volume guaranteed” in thoracic surgery with one lung ventilation

Egyptian Journal of Anaesthesia ◽

10.1016/j.egja.2011.04.004 ◽

2011 ◽

Vol 27 (2) ◽

pp. 113-119 ◽

Cited By ~ 8

Author(s):

Nermin S. Boules ◽

Hossam Z. Ghobrial

Keyword(s):

Thoracic Surgery ◽

Lung Ventilation ◽

One Lung Ventilation ◽

Ventilatory Mode ◽

Controlled Ventilation ◽

Pressure Controlled Ventilation ◽

Pressure Controlled

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A prospective evaluation of the new laryngeal tube suction-disposable in paralyzed, anesthetized pediatric patients under pressure-controlled ventilation

Minerva Anestesiologica ◽

10.23736/s0375-9393.20.14594-2 ◽

2020 ◽

Vol 86 (9) ◽

Author(s):

Mostafa Somri ◽

Luis A. Gaitini ◽

Anan Safadi ◽

Jalaa Hossein ◽

Nashed Ebraheem ◽

...

Keyword(s):

Pediatric Patients ◽

Laryngeal Tube ◽

Prospective Evaluation ◽

Controlled Ventilation ◽

Pressure Controlled Ventilation ◽

Tube Suction ◽

Pressure Controlled

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Comparison of Volume-Guaranteed or -Targeted, Pressure-Controlled Ventilation with Volume-Controlled Ventilation during Elective Surgery: A Systematic Review and Meta-Analysis

Journal of Clinical Medicine ◽

10.3390/jcm10061276 ◽

2021 ◽

Vol 10 (6) ◽

pp. 1276

Author(s):

Volker Schick ◽

Fabian Dusse ◽

Ronny Eckardt ◽

Steffen Kerkhoff ◽

Simone Commotio ◽

...

Keyword(s):

Systematic Review ◽

Elective Surgery ◽

Meta Analysis ◽

Lung Ventilation ◽

One Lung Ventilation ◽

Controlled Ventilation ◽

Pressure Controlled Ventilation ◽

Volume Controlled Ventilation ◽

Volume Controlled ◽

Pressure Controlled

For perioperative mechanical ventilation under general anesthesia, modern respirators aim at combining the benefits of pressure-controlled ventilation (PCV) and volume-controlled ventilation (VCV) in modes typically named “volume-guaranteed” or “volume-targeted” pressure-controlled ventilation (PCV-VG). This systematic review and meta-analysis tested the hypothesis that PCV-VG modes of ventilation could be beneficial in terms of improved airway pressures (Ppeak, Pplateau, Pmean), dynamic compliance (Cdyn), or arterial blood gases (PaO2, PaCO2) in adults undergoing elective surgery under general anesthesia. Three major medical electronic databases were searched with predefined search strategies and publications were systematically evaluated according to the Cochrane Review Methods. Continuous variables were tested for mean differences using the inverse variance method and 95% confidence intervals (CI) were calculated. Based on the assumption that intervention effects across studies were not identical, a random effects model was chosen. Assessment for heterogeneity was performed with the χ2 test and the I2 statistic. As primary endpoints, Ppeak, Pplateau, Pmean, Cdyn, PaO2, and PaCO2 were evaluated. Of the 725 publications identified, 17 finally met eligibility criteria, with a total of 929 patients recruited. Under supine two-lung ventilation, PCV-VG resulted in significantly reduced Ppeak (15 studies) and Pplateau (9 studies) as well as higher Cdyn (9 studies), compared with VCV [random effects models; Ppeak: CI −3.26 to −1.47; p < 0.001; I2 = 82%; Pplateau: −3.12 to −0.12; p = 0.03; I2 = 90%; Cdyn: CI 3.42 to 8.65; p < 0.001; I2 = 90%]. For one-lung ventilation (8 studies), PCV-VG allowed for significantly lower Ppeak and higher PaO2 compared with VCV. In Trendelenburg position (5 studies), this effect was significant for Ppeak only. This systematic review and meta-analysis demonstrates that volume-targeting, pressure-controlled ventilation modes may provide benefits with respect to the improved airway dynamics in two- and one-lung ventilation, and improved oxygenation in one-lung ventilation in adults undergoing elective surgery.

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