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Peták F, Südy R, Diaper J, Fontao F, Bizzotto D, Dellacà RL, Habre W, Schranc Á. Benefits of intratracheal and extrathoracic high-frequency percussive ventilation in a model of capnoperitoneum. J Appl Physiol (1985) 2024; 136:928-937. [PMID: 38420682 DOI: 10.1152/japplphysiol.00881.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 01/29/2024] [Accepted: 02/20/2024] [Indexed: 03/02/2024] Open
Abstract
Abdominal inflation with CO2 is used to facilitate laparoscopic surgeries, however, providing adequate mechanical ventilation in this scenario is of major importance during anesthesia management. We characterized high-frequency percussive ventilation (HFPV) in protecting from the gas exchange and respiratory mechanical impairments during capnoperitoneum. In addition, we aimed to assess the difference between conventional pressure-controlled mechanical ventilation (CMV) and HFPV modalities generating the high-frequency signal intratracheally (HFPVi) or extrathoracally (HFPVe). Anesthetized rabbits (n = 16) were mechanically ventilated by random sequences of CMV, HFPVi, and HFPVe. The ventilator superimposed the conventional waveform with two high-frequency signals (5 Hz and 10 Hz) during intratracheal HFPV (HFPVi) and HFPV with extrathoracic application of oscillatory signals through a sealed chest cuirass (HFPVe). Lung oxygenation index ([Formula: see text]/[Formula: see text]), arterial partial pressure of carbon dioxide ([Formula: see text]), intrapulmonary shunt (Qs/Qt), and respiratory mechanics were assessed before abdominal inflation, during capnoperitoneum, and after abdominal deflation. Compared with CMV, HFPVi with additional 5-Hz oscillations during capnoperitoneum resulted in higher [Formula: see text]/[Formula: see text], lower [Formula: see text], and decreased Qs/Qt. These improvements were smaller but remained significant during HFPVi with 10 Hz and HFPVe with either 5 or 10 Hz. The ventilation modes did not protect against capnoperitoneum-induced deteriorations in respiratory tissue mechanics. These findings suggest that high-frequency oscillations combined with conventional pressure-controlled ventilation improved lung oxygenation and CO2 removal in a model of capnoperitoneum. Compared with extrathoracic pressure oscillations, intratracheal generation of oscillatory pressure bursts appeared more effective. These findings may contribute to the optimization of mechanical ventilation during laparoscopic surgery.NEW & NOTEWORTHY The present study examines an alternative and innovative mechanical ventilation modality in improving oxygen delivery, CO2 clearance, and respiratory mechanical abnormalities in a clinically relevant experimental model of capnoperitoneum. Our data reveal that high-frequency oscillations combined with conventional ventilation improve gas exchange, with intratracheal oscillations being more effective than extrathoracic oscillations in this clinically relevant translational model.
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Affiliation(s)
- Ferenc Peták
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Roberta Südy
- Unit for Anesthesiological Investigations, Department of Acute Medicine, University of Geneva, Geneva, Switzerland
| | - John Diaper
- Unit for Anesthesiological Investigations, Department of Acute Medicine, University of Geneva, Geneva, Switzerland
| | - Fabienne Fontao
- Unit for Anesthesiological Investigations, Department of Acute Medicine, University of Geneva, Geneva, Switzerland
| | - Davide Bizzotto
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy
| | - Raffaele L Dellacà
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy
| | - Walid Habre
- Unit for Anesthesiological Investigations, Department of Acute Medicine, University of Geneva, Geneva, Switzerland
| | - Álmos Schranc
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
- Unit for Anesthesiological Investigations, Department of Acute Medicine, University of Geneva, Geneva, Switzerland
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Tolnai J, Ballók B, Südy R, Schranc Á, Varga G, Babik B, Fodor GH, Peták F. Changes in lung mechanics and ventilation-perfusion match: comparison of pulmonary air- and thromboembolism in rats. BMC Pulm Med 2024; 24:27. [PMID: 38200483 PMCID: PMC10782734 DOI: 10.1186/s12890-024-02842-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 01/03/2024] [Indexed: 01/12/2024] Open
Abstract
BACKGROUND Pulmonary air embolism (AE) and thromboembolism lead to severe ventilation-perfusion defects. The spatial distribution of pulmonary perfusion dysfunctions differs substantially in the two pulmonary embolism pathologies, and the effects on respiratory mechanics, gas exchange, and ventilation-perfusion match have not been compared within a study. Therefore, we compared changes in indices reflecting airway and respiratory tissue mechanics, gas exchange, and capnography when pulmonary embolism was induced by venous injection of air as a model of gas embolism or by clamping the main pulmonary artery to mimic severe thromboembolism. METHODS Anesthetized and mechanically ventilated rats (n = 9) were measured under baseline conditions after inducing pulmonary AE by injecting 0.1 mL air into the femoral vein and after occluding the left pulmonary artery (LPAO). Changes in mechanical parameters were assessed by forced oscillations to measure airway resistance, lung tissue damping, and elastance. The arterial partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) were determined by blood gas analyses. Gas exchange indices were also assessed by measuring end-tidal CO2 concentration (ETCO2), shape factors, and dead space parameters by volumetric capnography. RESULTS In the presence of a uniform decrease in ETCO2 in the two embolism models, marked elevations in the bronchial tone and compromised lung tissue mechanics were noted after LPAO, whereas AE did not affect lung mechanics. Conversely, only AE deteriorated PaO2, and PaCO2, while LPAO did not affect these outcomes. Neither AE nor LPAO caused changes in the anatomical or physiological dead space, while both embolism models resulted in elevated alveolar dead space indices incorporating intrapulmonary shunting. CONCLUSIONS Our findings indicate that severe focal hypocapnia following LPAO triggers bronchoconstriction redirecting airflow to well-perfused lung areas, thereby maintaining normal oxygenation, and the CO2 elimination ability of the lungs. However, hypocapnia in diffuse pulmonary perfusion after AE may not reach the threshold level to induce lung mechanical changes; thus, the compensatory mechanisms to match ventilation to perfusion are activated less effectively.
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Affiliation(s)
- József Tolnai
- Department of Medical Physics and Informatics, University of Szeged, 9 Korányi fasor, Szeged, H-6720, Hungary
| | - Bence Ballók
- Department of Medical Physics and Informatics, University of Szeged, 9 Korányi fasor, Szeged, H-6720, Hungary
| | - Roberta Südy
- Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, 1 Rue Michel-Servet, 1206, Geneva, Switzerland
| | - Álmos Schranc
- Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, 1 Rue Michel-Servet, 1206, Geneva, Switzerland
| | - Gabriella Varga
- Institute of Surgical Research, University of Szeged, 1 Pulz utca, Szeged, H-6724, Hungary
| | - Barna Babik
- Department of Anesthesiology and Intensive Therapy, University of Szeged, 6 Semmelweis str., Szeged, H-6725, Hungary
| | - Gergely H Fodor
- Department of Medical Physics and Informatics, University of Szeged, 9 Korányi fasor, Szeged, H-6720, Hungary
| | - Ferenc Peták
- Department of Medical Physics and Informatics, University of Szeged, 9 Korányi fasor, Szeged, H-6720, Hungary.
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Jeleff A, Suh N, Schranc Á, Diaper J, Bendjelid K, Schiffer E. New Noninvasive Method for the Assessment of Central Venous Oxygen Saturations in Critically Ill Patients. J Cardiothorac Vasc Anesth 2024; 38:170-174. [PMID: 37827917 DOI: 10.1053/j.jvca.2023.09.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 09/05/2023] [Accepted: 09/15/2023] [Indexed: 10/14/2023]
Abstract
OBJECTIVES To compare noninvasive external jugular vein oxygen saturations (SjvO2) and central venous oxygen saturation (ScvO2) from a blood sample in patients admitted to the intensive care unit. DESIGN A prospective, comparative, monocentric clinical trial design was used. SETTING The study was performed in the Department of Anaesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University Hospitals of Geneva (Switzerland). PARTICIPANTS A total of 79 patients were enrolled; patients with confirmed COVID-19 infection requiring invasive mechanical ventilation (patients with COVID-19, n = 36) and patients after liver transplantation (posttransplant patients, n = 43). INTERVENTIONS Simultaneous measurement of SjvO2 by near-infrared spectroscopy and ScvO2 from central venous blood samples using a blood gas analyzer in stable hemodynamic conditions. MEASUREMENTS AND MAIN RESULTS A strong linear correlation was evidenced in both the COVID-19 and posttransplant patient groups between the 2 modalities. The Bland-Altman analysis showed low bias in accordance with low percentage error in both groups (0.57% and 8.09% for patients with COVID-19; 0.00% and 13.72% for posttransplant patients). CONCLUSIONS Central venous oxygen saturation can be estimated reasonably by the continuous noninvasive measurement of SjvO2 using near-infrared spectroscopy.
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Affiliation(s)
- Alexandre Jeleff
- Division of Anaesthesiology, Department of Anaesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University Hospitals of Geneva, Geneva, Switzerland
| | - Noémie Suh
- Division of Intensive Care, Department of Anaesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University Hospitals of Geneva, Geneva, Switzerland
| | - Álmos Schranc
- Unit for Anaesthesiological Investigations, Department of Anaesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland.
| | - John Diaper
- Division of Anaesthesiology, Department of Anaesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University Hospitals of Geneva, Geneva, Switzerland; Unit for Anaesthesiological Investigations, Department of Anaesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
| | - Karim Bendjelid
- Division of Intensive Care, Department of Anaesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University Hospitals of Geneva, Geneva, Switzerland
| | - Eduardo Schiffer
- Division of Anaesthesiology, Department of Anaesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University Hospitals of Geneva, Geneva, Switzerland
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Ballók B, Schranc Á, Tóth I, Somogyi P, Tolnai J, Peták F, Fodor GH. Comparison of the respiratory effects of commonly utilized general anaesthesia regimes in male Sprague-Dawley rats. Front Physiol 2023; 14:1249127. [PMID: 37791348 PMCID: PMC10544940 DOI: 10.3389/fphys.2023.1249127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 09/05/2023] [Indexed: 10/05/2023] Open
Abstract
Background: Respiratory parameters in experimental animals are often characterised under general anaesthesia. However, anaesthesia regimes may alter the functional and mechanical properties of the respiratory system. While most anaesthesia regimes have been shown to affect the respiratory system, the effects of general anaesthesia protocols commonly used in animal models on lung function have not been systematically compared. Methods: The present study comprised 40 male Sprague-Dawley rats divided into five groups (N = 8 in each) according to anaesthesia regime applied: intravenous (iv) Na-pentobarbital, intraperitoneal (ip) ketamine-xylazine, iv propofol-fentanyl, inhaled sevoflurane, and ip urethane. All drugs were administered at commonly used doses. End-expiratory lung volume (EELV), airway resistance (Raw) and tissue mechanics were measured in addition to arterial blood gas parameters during mechanical ventilation while maintaining positive end-expiratory pressure (PEEP) values of 0, 3, and 6 cm H2O. Respiratory mechanics were also measured during iv methacholine (MCh) challenges to assess bronchial responsiveness. Results: While PEEP influenced baseline respiratory mechanics, EELV and blood gas parameters (p < 0.001), no between-group differences were observed (p > 0.10). Conversely, significantly lower doses of MCh were required to achieve the same elevation in Raw under ketamine-xylazine anaesthesia compared to the other groups. Conclusion: In the most frequent rodent model of respiratory disorders, no differences in baseline respiratory mechanics or function were observed between commonly used anaesthesia regimes. Bronchial hyperresponsiveness in response to ketamine-xylazine anaesthesia should be considered when designing experiments using this regime. The findings of the present study indicate commonly used anaesthetic regimes allow fair comparison of respiratory mechanics in experimental animals undergoing any of the examined anaesthesia protocols.
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Affiliation(s)
- Bence Ballók
- Department of Medical Physics and Informatics, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
| | - Álmos Schranc
- Department of Medical Physics and Informatics, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
- Unit for Anaesthesiological Investigations, Department of Anaesthesiology, Pharmacology, Intensive Care, and Emergency Medicine, University of Geneva, Geneva, Switzerland
| | - Ibolya Tóth
- Department of Medical Physics and Informatics, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
| | - Petra Somogyi
- Department of Medical Physics and Informatics, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
- Department of Cell Biology and Molecular Medicine, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
| | - József Tolnai
- Department of Medical Physics and Informatics, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
| | - Ferenc Peták
- Department of Medical Physics and Informatics, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
| | - Gergely H. Fodor
- Department of Medical Physics and Informatics, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
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Schranc Á, Diaper J, Südy R, Peták F, Habre W, Albu G. Lung recruitment by continuous negative extra-thoracic pressure support following one-lung ventilation: an experimental study. Front Physiol 2023; 14:1160731. [PMID: 37256073 PMCID: PMC10225513 DOI: 10.3389/fphys.2023.1160731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 05/03/2023] [Indexed: 06/01/2023] Open
Abstract
Lung recruitment maneuvers following one-lung ventilation (OLV) increase the risk for the development of acute lung injury. The application of continuous negative extrathoracic pressure (CNEP) is gaining interest both in intubated and non-intubated patients. However, there is still a lack of knowledge on the ability of CNEP support to recruit whole lung atelectasis following OLV. We investigated the effects of CNEP following OLV on lung expansion, gas exchange, and hemodynamics. Ten pigs were anesthetized and mechanically ventilated with pressure-regulated volume control mode (PRVC; FiO2: 0.5, Fr: 30-35/min, VT: 7 mL/kg, PEEP: 5 cmH2O) for 1 hour, then baseline (BL) data for gas exchange (arterial partial pressure of oxygen, PaO2; and carbon dioxide, PaCO2), ventilation and hemodynamical parameters and lung aeration by electrical impedance tomography were recorded. Subsequently, an endobronchial blocker was inserted, and OLV was applied with a reduced VT of 5 mL/kg. Following a new set of measurements after 1 h of OLV, two-lung ventilation was re-established, combining PRVC (VT: 7 mL/kg) and CNEP (-15 cmH2O) without any hyperinflation maneuver and data collection was then repeated at 5 min and 1 h. Compared to OLV, significant increases in PaO2 (154.1 ± 13.3 vs. 173.8 ± 22.1) and decreases in PaCO2 (52.6 ± 11.7 vs. 40.3 ± 4.5 mmHg, p < 0.05 for both) were observed 5 minutes following initiation of CNEP, and these benefits in gas exchange remained after an hour of CNEP. Gradual improvements in lung aeration in the non-collapsed lung were also detected by electrical impedance tomography (p < 0.05) after 5 and 60 min of CNEP. Hemodynamics and ventilation parameters remained stable under CNEP. Application of CNEP in the presence of whole lung atelectasis proved to be efficient in improving gas exchange via recruiting the lung without excessive airway pressures. These benefits of combined CNEP and positive pressure ventilation may have particular value in relieving atelectasis in the postoperative period of surgical procedures requiring OLV.
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Affiliation(s)
- Álmos Schranc
- Unit for Anesthesiological Investigations, Department of Anesthesiology Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
| | - John Diaper
- Unit for Anesthesiological Investigations, Department of Anesthesiology Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
| | - Roberta Südy
- Unit for Anesthesiological Investigations, Department of Anesthesiology Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
| | - Ferenc Peták
- Department of Medical Physics and Informatics, Albert Szent-Györgyi Medical School, University of Szeged, Szeged, Hungary
| | - Walid Habre
- Unit for Anesthesiological Investigations, Department of Anesthesiology Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
| | - Gergely Albu
- Unit for Anesthesiological Investigations, Department of Anesthesiology Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
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Schranc Á, Diaper J, Südy R, Fodor GH, Habre W, Albu G. Benefit of Flow-Controlled Over Pressure-Regulated Volume Control Mode During One-Lung Ventilation: A Randomized Experimental Crossover Study. Anesth Analg 2023; 136:605-612. [PMID: 36729097 DOI: 10.1213/ane.0000000000006322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Application of a ventilation modality that ensures adequate gas exchange during one-lung ventilation (OLV) without inducing lung injury is of paramount importance. Due to its beneficial effects on respiratory mechanics and gas exchange, flow-controlled ventilation (FCV) may be considered as a protective alternative mode of traditional pressure- or volume-controlled ventilation during OLV. We investigated whether this new modality provides benefits compared with conventional ventilation modality for OLV. METHODS Ten pigs were anaesthetized and randomly assigned in a crossover design to be ventilated with FCV or pressure-regulated volume control (PRVC) ventilation. Arterial partial pressure of oxygen (Pa o2 ), carbon dioxide (Pa co2 ), ventilation and hemodynamical parameters, and lung aeration measured by electrical impedance tomography were assessed at baseline and 1 hour after the application of each modality during OLV using an endobronchial blocker. RESULTS Compared to PRVC, FCV resulted in increased Pa o2 (153.7 ± 12.7 vs 169.9 ± 15.0 mm Hg; P = .002) and decreased Pa co2 (53.0 ± 11.0 vs 43.2 ± 6.0 mm Hg; P < .001) during OLV, with lower respiratory elastance (103.7 ± 9.5 vs 77.2 ± 10.5 cm H 2 O/L; P < .001) and peak inspiratory pressure values (27.4 ± 1.9 vs 22.0 ± 2.3 cm H 2 O; P < .001). No differences in lung aeration or hemodynamics could be detected between the 2 ventilation modalities. CONCLUSIONS The application of FCV in OLV led to improvement in gas exchange and respiratory elastance with lower ventilatory pressures. Our findings suggest that FCV may offer an optimal, protective ventilation modality for OLV.
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Affiliation(s)
- Álmos Schranc
- From the Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
| | - John Diaper
- From the Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
| | - Roberta Südy
- From the Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
| | - Gergely H Fodor
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Walid Habre
- From the Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
- Pediatric Anesthesia Unit, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University Hospitals of Geneva, Geneva, Switzerland
| | - Gergely Albu
- From the Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
- Division of Anesthesiology, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University Hospitals of Geneva, Geneva, Switzerland
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Peták F, Fodor GH, Schranc Á, Südy R, Balogh ÁL, Babik B, Dos Santos Rocha A, Bayat S, Bizzotto D, Dellacà RL, Habre W. Expiratory high-frequency percussive ventilation: a novel concept for improving gas exchange. Respir Res 2022; 23:283. [PMID: 36243752 PMCID: PMC9569091 DOI: 10.1186/s12931-022-02215-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 10/06/2022] [Indexed: 11/25/2022] Open
Abstract
Background Although high-frequency percussive ventilation (HFPV) improves gas exchange, concerns remain about tissue overdistension caused by the oscillations and consequent lung damage. We compared a modified percussive ventilation modality created by superimposing high-frequency oscillations to the conventional ventilation waveform during expiration only (eHFPV) with conventional mechanical ventilation (CMV) and standard HFPV. Methods Hypoxia and hypercapnia were induced by decreasing the frequency of CMV in New Zealand White rabbits (n = 10). Following steady-state CMV periods, percussive modalities with oscillations randomly introduced to the entire breathing cycle (HFPV) or to the expiratory phase alone (eHFPV) with varying amplitudes (2 or 4 cmH2O) and frequencies were used (5 or 10 Hz). The arterial partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) were determined. Volumetric capnography was used to evaluate the ventilation dead space fraction, phase 2 slope, and minute elimination of CO2. Respiratory mechanics were characterized by forced oscillations. Results The use of eHFPV with 5 Hz superimposed oscillation frequency and an amplitude of 4 cmH2O enhanced gas exchange similar to those observed after HFPV. These improvements in PaO2 (47.3 ± 5.5 vs. 58.6 ± 7.2 mmHg) and PaCO2 (54.7 ± 2.3 vs. 50.1 ± 2.9 mmHg) were associated with lower ventilation dead space and capnogram phase 2 slope, as well as enhanced minute CO2 elimination without altering respiratory mechanics. Conclusions These findings demonstrated improved gas exchange using eHFPV as a novel mechanical ventilation modality that combines the benefits of conventional and small-amplitude high-frequency oscillatory ventilation, owing to improved longitudinal gas transport rather than increased lung surface area available for gas exchange. Supplementary Information The online version contains supplementary material available at 10.1186/s12931-022-02215-2.
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Affiliation(s)
- Ferenc Peták
- Department of Medical Physics and Informatics, University of Szeged, 9, Korányi fasor, Szeged, 6720, Hungary.
| | - Gergely H Fodor
- Department of Medical Physics and Informatics, University of Szeged, 9, Korányi fasor, Szeged, 6720, Hungary
| | - Álmos Schranc
- Department of Medical Physics and Informatics, University of Szeged, 9, Korányi fasor, Szeged, 6720, Hungary
| | - Roberta Südy
- Department of Medical Physics and Informatics, University of Szeged, 9, Korányi fasor, Szeged, 6720, Hungary.,Department of Anaesthesiology and Intensive Therapy, University of Szeged, Szeged, Hungary
| | - Ádám L Balogh
- Unit for Anaesthesiological Investigations, Department of Acute Medicine, University of Geneva, Geneva, Switzerland
| | - Barna Babik
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, Szeged, Hungary
| | - André Dos Santos Rocha
- Unit for Anaesthesiological Investigations, Department of Acute Medicine, University of Geneva, Geneva, Switzerland
| | - Sam Bayat
- Univ. Grenoble Alpes, Inserm UA07 STROBE Laboratory & Department of Pneumology and Clinical Physiology, Grenoble University Hospital, Grenoble, France
| | - Davide Bizzotto
- Dipartimento Di Elettronica, Informazione E Bioingegneria, Politecnico di Milano, Milan, Italy
| | - Raffaele L Dellacà
- Dipartimento Di Elettronica, Informazione E Bioingegneria, Politecnico di Milano, Milan, Italy
| | - Walid Habre
- Unit for Anaesthesiological Investigations, Department of Acute Medicine, University of Geneva, Geneva, Switzerland.,Paediatric Anaesthesia Unit, Department of Acute Medicine, University Hospitals of Geneva, Geneva, Switzerland
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Schranc Á, Fodor GH, Südy R, Tolnai J, Babik B, Peták F. Exaggerated Ventilator-Induced Lung Injury in an Animal Model of Type 2 Diabetes Mellitus: A Randomized Experimental Study. Front Physiol 2022; 13:889032. [PMID: 35733997 PMCID: PMC9207264 DOI: 10.3389/fphys.2022.889032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
Abstract
Although ventilator-induced lung injury (VILI) often develops after prolonged mechanical ventilation in normal lungs, pulmonary disorders may aggravate the development of adverse symptoms. VILI exaggeration can be anticipated in type 2 diabetes mellitus (T2DM) due to its adverse pulmonary consequences. Therefore, we determined whether T2DM modulates VILI and evaluated how T2DM therapy affects adverse pulmonary changes. Rats were randomly assigned into the untreated T2DM group receiving low-dose streptozotocin with high-fat diet (T2DM, n = 8), T2DM group supplemented with metformin therapy (MET, n = 8), and control group (CTRL, n = 8). In each animal, VILI was induced by mechanical ventilation for 4 h with high tidal volume (23 ml/kg) and low positive end-expiratory pressure (0 cmH2O). Arterial and venous blood samples were analyzed to measure the arterial partial pressure of oxygen (PaO2), oxygen saturation (SaO2), and the intrapulmonary shunt fraction (Qs/Qt). Airway and respiratory tissue mechanics were evaluated by forced oscillations. Lung histology samples were analyzed to determine injury level. Significant worsening of VILI, in terms of PaO2, SaO2, and Qs/Qt, was observed in the T2DM group, without differences in the respiratory mechanics. These functional changes were also reflected in lung injury score. The MET group showed no difference compared with the CTRL group. Gas exchange impairment without significant mechanical changes suggests that untreated diabetes exaggerates VILI by augmenting the damage of the alveolar–capillary barrier. Controlled hyperglycemia with metformin may reduce the manifestations of respiratory defects during prolonged mechanical ventilation.
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Affiliation(s)
- Álmos Schranc
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Gergely H. Fodor
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Roberta Südy
- Unit for Anesthesiological Investigations, Department of Acute Medicine, University of Geneva, Geneva, Switzerland
| | - József Tolnai
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Barna Babik
- Department of Anesthesiology and Intensive Therapy, University of Szeged, Szeged, Hungary
| | - Ferenc Peták
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
- *Correspondence: Ferenc Peták,
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Kovács BN, Südy R, Peták F, Balogh ÁL, Fodor HG, Tolnai J, Korsós A, Schranc Á, Lengyel C, Babik B. Respiratory consequences of obesity and diabetes. Orv Hetil 2022; 163:63-73. [PMID: 34999572 DOI: 10.1556/650.2022.32335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 07/26/2021] [Indexed: 11/19/2022]
Abstract
Összefoglaló. Bevezetés: A cukorbetegségben nő a simaizmok tónusa, és megváltozik az elasztin és a kollagén szerkezete. Mivel a tüdőszövetben ezek a strukturális elemek meghatározóak, a cukorbetegség várhatóan módosítja a légutak és a tüdőszövet mechanikai és funkcionális viselkedését. Célkitűzés: Vizsgálatunk során diabetesben szenvedő, elhízott és nem elhízott betegeink körében tanulmányoztuk a légzésmechanikai elváltozásokat és a gázcserefunkciót. Módszer: Elektív szívsebészeti beavatkozásra kerülő, normál testalkatú betegeket diabetesben nem szenvedő (n = 80), illetve cukorbeteg (n = 35) csoportokra osztottuk. További két betegcsoportba elhízott és nem cukorbeteg (n = 47), valamint elhízott és diabetesben szenvedő (n = 33) betegek kerültek. A légzőrendszer mechanikai tulajdonságait kényszerített oszcillációs technikával határoztuk meg, mellyel a légúti ellenállás (Raw), valamint a szöveti csillapítás (G) és rugalmasság (H) tényezői jellemezhetők. Volumetriás kapnográfia segítségével a kapnogram 3. fázisának meredekségét és a légzési térfogat különböző ventilációs/perfúziós illeszkedési zavaraiból adódó holttérfrakciókat határoztuk meg. Az intrapulmonalis shuntfrakciót és az oxigenizációs indexet (PaO2/FiO2) artériás és centrális vénás vérgázmintákból határoztuk meg. Eredmények: A megfelelő kontrollcsoportokhoz hasonlítva a cukorbetegség önmagában is növelte az Raw (7,4 ± 5 vs. 3,0 ± 1,7 H2Ocm.s/l), a G (11,3 ± 4,9 vs. 6,2 ± 2,4 H2Ocm/l) és a H (32,3 ± 12,0 vs. 25,1± 6,9 H2Ocm/l) értékét (p<0,001 mindegyik betegcsoportnál), de ez nem járt együtt a gázcserefunckció romlásával. Hasonló patológiás elváltozásokat észleltünk elhízás során a légzésmechanikában és az alveolaris heterogenitásban, amelyek azonban a gázcsere hatékonyságát is rontották. Következtetés: Cukorbetegségben a légzésmechanika romlását a fokozott hypoxiás pulmonalis vasoconstrictio ellensúlyozni képes, ezzel kivédve az intrapulmonalis shunt növekedését és az oxigenizációs képesség romlását. Orv Hetil. 2022; 163(2): 63-73. SUMMARY INTRODUCTION While sustained hyperglicemia affects the smooth muscle tone and the elastin-collagen network, the effect of diabetes mellitus on the function and structure of the airways and the lung parenchyma has not been characterized, and the confounding influence of obesity has not been elucidated. OBJECTIVE To reveal the separate and additive roles of diabetes mellitus and obesity on the respiratory function. METHOD Non-obese mechanically ventilated patients were categorized as control non-diabetic (n = 80) and diabetic (n = 35) groups. Obese patients with (n = 33) or without (n = 47) associated diabetes were also enrolled. Forced oscillation technique was applied to measure airway resistance (Raw), tissue damping (G), and tissue elastance (H). Capnography was utilized to determine phase 3 slopes and ventilation dead space parameters. Arterial and central venous blood samples were analyzed to assess intrapulmonary shunt fraction (Qs/Qt) and the lung oxygenation index (PaO2/FiO2). RESULTS Diabetes without obesity increased the Raw (7.4 ± 5 cmH2O.s/l vs. 3.0 ± 1.7 cmH2O.s/l), G (11.3 ± 4.9 cmH2O/l vs. 6.2 ± 2.4 cmH2O/l), and H (32.3 ± 12.0 cmH2O/l vs. 25.1 ± 6.9 cmH2O/l, (p<0.001 for all), compared with the corresponding control groups. Capnographic phase 3 slope was increased in diabetes without significant changes in PaO2/FiO2 or Qs/Qt. While similar detrimental changes in respiratory mechanics and alveolar heterogeneity were observed in obese patients without diabetes, these alterations also compromised gas exchange. CONCLUSION The intrinsic mechanical abnormalities in the airways and lung tissue induced by diabetes are counterbalanced by hypoxic pulmonary vasoconstriction, thereby maintaining intrapulmonary shunt fraction and oxygenation ability of the lungs. Orv Hetil. 2022; 163(2): 63-73.
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Affiliation(s)
- Barbara Nóra Kovács
- 1 Szegedi Tudományegyetem, Általános Orvostudományi Kar, Aneszteziológiai és Intenzív Terápiás Intézet Szeged, Semmelweis u. 6., 6720.,2 Szegedi Tudományegyetem, Általános Orvostudományi Kar, Orvosi Fizikai és Orvosi Informatikai Intézet Szeged
| | - Roberta Südy
- 1 Szegedi Tudományegyetem, Általános Orvostudományi Kar, Aneszteziológiai és Intenzív Terápiás Intézet Szeged, Semmelweis u. 6., 6720.,2 Szegedi Tudományegyetem, Általános Orvostudományi Kar, Orvosi Fizikai és Orvosi Informatikai Intézet Szeged
| | - Ferenc Peták
- 2 Szegedi Tudományegyetem, Általános Orvostudományi Kar, Orvosi Fizikai és Orvosi Informatikai Intézet Szeged
| | - Ádám László Balogh
- 1 Szegedi Tudományegyetem, Általános Orvostudományi Kar, Aneszteziológiai és Intenzív Terápiás Intézet Szeged, Semmelweis u. 6., 6720.,2 Szegedi Tudományegyetem, Általános Orvostudományi Kar, Orvosi Fizikai és Orvosi Informatikai Intézet Szeged
| | - H Gergely Fodor
- 2 Szegedi Tudományegyetem, Általános Orvostudományi Kar, Orvosi Fizikai és Orvosi Informatikai Intézet Szeged
| | - József Tolnai
- 2 Szegedi Tudományegyetem, Általános Orvostudományi Kar, Orvosi Fizikai és Orvosi Informatikai Intézet Szeged
| | - Anita Korsós
- 1 Szegedi Tudományegyetem, Általános Orvostudományi Kar, Aneszteziológiai és Intenzív Terápiás Intézet Szeged, Semmelweis u. 6., 6720
| | - Álmos Schranc
- 2 Szegedi Tudományegyetem, Általános Orvostudományi Kar, Orvosi Fizikai és Orvosi Informatikai Intézet Szeged
| | - Csaba Lengyel
- 3 Szegedi Tudományegyetem, Általános Orvostudományi Kar, Belgyógyászati Klinika Szeged
| | - Barna Babik
- 1 Szegedi Tudományegyetem, Általános Orvostudományi Kar, Aneszteziológiai és Intenzív Terápiás Intézet Szeged, Semmelweis u. 6., 6720
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10
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Schranc Á, Balogh ÁL, Diaper J, Südy R, Peták F, Habre W, Albu G. Flow-controlled ventilation maintains gas exchange and lung aeration in a pediatric model of healthy and injured lungs: A randomized cross-over experimental study. Front Pediatr 2022; 10:1005135. [PMID: 36160799 PMCID: PMC9500311 DOI: 10.3389/fped.2022.1005135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 08/24/2022] [Indexed: 11/30/2022] Open
Abstract
Flow-controlled ventilation (FCV) is characterized by a constant flow to generate active inspiration and expiration. While the benefit of FCV on gas exchange has been demonstrated in preclinical and clinical studies with adults, the value of this modality for a pediatric population remains unknown. Thus, we aimed at observing the effects of FCV as compared to pressure-regulated volume control (PRVC) ventilation on lung mechanics, gas exchange and lung aeration before and after surfactant depletion in a pediatric model. Ten anesthetized piglets (10.4 ± 0.2 kg) were randomly assigned to start 1-h ventilation with FCV or PRVC before switching the ventilation modes for another hour. This sequence was repeated after inducing lung injury by bronchoalveolar lavage and injurious ventilation. The primary outcome was respiratory tissue elastance. Secondary outcomes included oxygenation index (PaO2/FiO2), PaCO2, intrapulmonary shunt (Qs/Qt), airway resistance, respiratory tissue damping, end-expiratory lung volume, lung clearance index and lung aeration by chest electrical impedance tomography. Measurements were performed at the end of each protocol stage. Ventilation modality had no effect on any respiratory mechanical parameter. Adequate gas exchange was provided by FCV, similar to PRVC, with sufficient CO2 elimination both in healthy and surfactant-depleted lungs (39.46 ± 7.2 mmHg and 46.2 ± 11.4 mmHg for FCV; 36.0 ± 4.1 and 39.5 ± 4.9 mmHg, for PRVC, respectively). Somewhat lower PaO2/FiO2 and higher Qs/Qt were observed in healthy and surfactant depleted lungs during FCV compared to PRVC (p < 0.05, for all). Compared to PRVC, lung aeration was significantly elevated, particularly in the ventral dependent zones during FCV (p < 0.05), but this difference was not evidenced in injured lungs. Somewhat lower oxygenation and higher shunt ratio was observed during FCV, nevertheless lung aeration improved and adequate gas exchange was ensured. Therefore, in the absence of major differences in respiratory mechanics and lung volumes, FCV may be considered as an alternative in ventilation therapy of pediatric patients with healthy and injured lungs.
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Affiliation(s)
- Álmos Schranc
- Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
| | - Ádám L Balogh
- Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
| | - John Diaper
- Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
| | - Roberta Südy
- Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland
| | - Ferenc Peták
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Walid Habre
- Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland.,Pediatric Anesthesia Unit, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University Hospitals of Geneva, Geneva, Switzerland
| | - Gergely Albu
- Unit for Anesthesiological Investigations, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University of Geneva, Geneva, Switzerland.,Division of Anesthesiology, Department of Anesthesiology, Pharmacology, Intensive Care and Emergency Medicine, University Hospitals of Geneva, Geneva, Switzerland
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Korsós A, Peták F, Südy R, Schranc Á, Fodor GH, Babik B. Use of capnography to verify emergency ventilator sharing in the COVID-19 era. Respir Physiol Neurobiol 2021; 285:103611. [PMID: 33359758 PMCID: PMC7832691 DOI: 10.1016/j.resp.2020.103611] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 12/10/2020] [Accepted: 12/21/2020] [Indexed: 01/29/2023]
Abstract
Exacerbation of COVID-19 pandemic may lead to acute shortage of ventilators, which may require shared use of ventilator as a lifesaving concept. Two model lungs were ventilated with one ventilator to i) test the adequacy of individual tidal volumes via capnography, ii) assess cross-breathing between lungs, and iii) offer a simulation-based algorithm for ensuring equal tidal volumes. Ventilation asymmetry was induced by placing rubber band around one model lung, and the uneven distribution of tidal volumes (VT) was counterbalanced by elevating airflow resistance (HR) contralaterally. VT, end-tidal CO2 concentration (ETCO2), and peak inspiratory pressure (Ppi) were measured. Unilateral LC reduced VT and elevated ETCO2 on the affected side. Under HR, VT and ETCO2 were re-equilibrated. In conclusion, capnography serves as simple, bedside method for controlling the adequacy of split ventilation in each patient. No collateral gas flow was observed between the two lungs with different time constants. Ventilator sharing may play a role in emergency situations.
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Affiliation(s)
- Anita Korsós
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, 6 Semmelweis Street, H 6725, Szeged, Hungary
| | - Ferenc Peták
- Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi Fasor, H 6720, Szeged, Hungary.
| | - Roberta Südy
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, 6 Semmelweis Street, H 6725, Szeged, Hungary
| | - Álmos Schranc
- Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi Fasor, H 6720, Szeged, Hungary
| | - Gergely H Fodor
- Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi Fasor, H 6720, Szeged, Hungary
| | - Barna Babik
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, 6 Semmelweis Street, H 6725, Szeged, Hungary
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Südy R, Peták F, Kiss L, Balogh ÁL, Fodor GH, Korsós A, Schranc Á, Babik B. Obesity and diabetes: similar respiratory mechanical but different gas exchange defects. Am J Physiol Lung Cell Mol Physiol 2020; 320:L368-L376. [PMID: 33264577 DOI: 10.1152/ajplung.00439.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Diabetes mellitus increases smooth muscle tone and causes tissue remodeling, affecting elastin and collagen. Although the lung is dominated by these elements, diabetes is expected to modify the airway function and respiratory tissue mechanics. Therefore, we characterized the respiratory function in patients with diabetes with and without associated obesity. Mechanically ventilated patients with normal body shapes were divided into the control nondiabetic (n = 73) and diabetic (n = 31) groups. The other two groups included obese patients without diabetes (n = 43) or with diabetes (n = 30). The mechanical properties of the respiratory system were determined by forced oscillation technique. Airway resistance (Raw), tissue damping (G), and tissue elastance (H) were assessed by forced oscillation. Capnography was applied to determine phase 3 slopes and dead space indices. The intrapulmonary shunt fraction (Qs/Qt) and the lung oxygenation index (PaO2/FIO2) were estimated from arterial and central venous blood samples. Compared with the corresponding control groups, diabetes alone increased the Raw (7.6 ± 6 cmH2O.s/l vs. 3.1 ± 1.9 cmH2O.s/l), G (11.7 ± 5.5 cmH2O/l vs. 6.5 ± 2.8 cmH2O/l), and H (31.5 ± 11.8 cmH2O/l vs. 24.2 ± 7.2 cmH2O/l (P < 0.001 for all). Diabetes increased the capnographic phase 3 slope, whereas PaO2/FIO2 or Qs/Qt was not affected. Obesity alone caused similar detrimental changes in respiratory mechanics and alveolar heterogeneity, but these alterations also compromised gas exchange. We conclude that diabetes-induced intrinsic mechanical abnormalities are counterbalanced by hypoxic pulmonary vasoconstriction, which maintained intrapulmonary shunt fraction and oxygenation ability of the lungs.
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Affiliation(s)
- Roberta Südy
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, Szeged, Hungary.,Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Ferenc Peták
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Liliána Kiss
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, Szeged, Hungary.,Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Ádám L Balogh
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, Szeged, Hungary.,Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Gergely H Fodor
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Anita Korsós
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, Szeged, Hungary
| | - Álmos Schranc
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Barna Babik
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, Szeged, Hungary
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Südy R, Schranc Á, Fodor GH, Tolnai J, Babik B, Peták F. Lung volume dependence of respiratory function in rodent models of diabetes mellitus. Respir Res 2020; 21:82. [PMID: 32272932 PMCID: PMC7146915 DOI: 10.1186/s12931-020-01334-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 03/09/2020] [Indexed: 12/16/2022] Open
Abstract
Background Diabetes mellitus causes the deterioration of smooth muscle cells and interstitial matrix proteins, including collagen. Collagen and smooth muscle cells are abundant in the lungs, but the effect of diabetes on airway function and viscoelastic respiratory tissue mechanics has not been characterized. This study investigated the impact of diabetes on respiratory function, bronchial responsiveness, and gas exchange parameters. Methods Rats were allocated randomly to three groups: a model of type 1 diabetes that received a high dose of streptozotocin (DM1, n = 13); a model of type 2 diabetes that received a low dose of streptozotocin with a high-fat diet (DM2, n = 14); and a control group with no treatment (C, n = 14). Forced oscillations were applied to assess airway resistance (Raw), respiratory tissue damping (G), and elastance (H). The arterial partial pressure of oxygen to the inspired oxygen fraction (PaO2/FiO2) and intrapulmonary shunt fraction (Qs/Qt) were determined from blood gas samples at positive end-expiratory pressures (PEEPs) of 0, 3, and 6 cmH2O. Lung responsiveness to methacholine was also assessed. Collagen fibers in lung tissue were quantified by histology. Results The rats in groups DM1 and DM2 exhibited elevated Raw, G, H, and Qs/Qt, compromised PaO2/FiO2, and diminished airway responsiveness. The severity of adverse tissue mechanical change correlated with excessive lung collagen expression. Increased PEEP normalized the respiratory mechanics, but the gas exchange abnormalities remained. Conclusions These findings indicate that diabetes reduces airway and lung tissue viscoelasticity, resulting in alveolar collapsibility that can be compensated by increasing PEEP. Diabetes also induces persistent alveolo-capillary dysfunction and abnormal adaptation ability of the airways to exogenous constrictor stimuli.
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Affiliation(s)
- Roberta Südy
- Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi fasor, Szeged, H-6720, Hungary.,Department of Anaesthesiology and Intensive Therapy, University of Szeged, 6 Semmelweis Street, Szeged, H 6725, Hungary
| | - Álmos Schranc
- Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi fasor, Szeged, H-6720, Hungary.,Department of Anaesthesiology and Intensive Therapy, University of Szeged, 6 Semmelweis Street, Szeged, H 6725, Hungary
| | - Gergely H Fodor
- Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi fasor, Szeged, H-6720, Hungary
| | - József Tolnai
- Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi fasor, Szeged, H-6720, Hungary
| | - Barna Babik
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, 6 Semmelweis Street, Szeged, H 6725, Hungary
| | - Ferenc Peták
- Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi fasor, Szeged, H-6720, Hungary.
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14
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Südy R, Fodor GH, Dos Santos Rocha A, Schranc Á, Tolnai J, Habre W, Peták F. Different contributions from lungs and chest wall to respiratory mechanics in mice, rats, and rabbits. J Appl Physiol (1985) 2019; 127:198-204. [PMID: 31161880 DOI: 10.1152/japplphysiol.00048.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Changes in lung mechanics are frequently inferred from intact-chest measures of total respiratory system mechanics without consideration of the chest wall contribution. The participation of lungs and chest wall in respiratory mechanics has not been evaluated systematically in small animals commonly used in respiratory research. Thus, we compared these contributions in intact-chest mice, rats, and rabbits and further characterized the influence of positive end-expiratory pressure (PEEP). Forced oscillation technique was applied to anesthetized mechanically ventilated healthy animals to obtain total respiratory system impedance (Zrs) at 0, 3, and 6 cmH2O PEEP levels. Esophageal pressure was measured by a catheter-tip micromanometer to separate Zrs into pulmonary (ZL) and chest wall (Zcw) components. A model containing a frequency-independent Newtonian resistance (RN), inertance, and a constant-phase tissue damping (G) and elastance (H) was fitted to Zrs, ZL, and Zcw spectra. The contribution of Zcw to RN was negligible in all species and PEEP levels studied. However, the participation of Zcw in G and H was significant in all species and increased significantly with increasing PEEP and animal size (rabbit > rat > mice). Even in mice, the chest wall contribution to G and H was still considerable, reaching 47.0 ± 4.0(SE)% and 32.9 ± 5.9% for G and H, respectively. These findings demonstrate that airway parameters can be assessed from respiratory system mechanical measurements. However, the contribution from the chest wall should be considered when intact-chest measurements are used to estimate lung parenchymal mechanics in small laboratory models (even in mice), particularly at elevated PEEP levels. NEW & NOTEWORTHY In species commonly used in respiratory research (rabbits, rats, mice), esophageal pressure-based estimates revealed negligible contribution from the chest wall to the Newtonian resistance. Conversely, chest wall participation in the viscoelastic tissue mechanical parameters increased with body size (rabbit > rat > mice) and positive end-expiratory pressure, with contribution varying between 30 and 50%, even in mice. These findings demonstrate the potential biasing effects of the chest wall when lung tissue mechanics are inferred from intact-chest measurements in small laboratory animals.
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Affiliation(s)
- Roberta Südy
- Unit for Anesthesiological Investigations, Department of Acute Medicine, University of Geneva , Geneva , Switzerland.,Department of Medical Physics and Informatics, University of Szeged , Szeged , Hungary
| | - Gergely H Fodor
- Unit for Anesthesiological Investigations, Department of Acute Medicine, University of Geneva , Geneva , Switzerland
| | - André Dos Santos Rocha
- Unit for Anesthesiological Investigations, Department of Acute Medicine, University of Geneva , Geneva , Switzerland
| | - Álmos Schranc
- Department of Medical Physics and Informatics, University of Szeged , Szeged , Hungary
| | - József Tolnai
- Department of Medical Physics and Informatics, University of Szeged , Szeged , Hungary
| | - Walid Habre
- Unit for Anesthesiological Investigations, Department of Acute Medicine, University of Geneva , Geneva , Switzerland
| | - Ferenc Peták
- Department of Medical Physics and Informatics, University of Szeged , Szeged , Hungary
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