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Siddharthan T, Grealis K, Kirkness JP, Ötvös T, Stefanovski D, Tombleson A, Dalzell M, Gonzalez E, Nakrani KB, Wenger D, Lester MG, Richmond BW, Fouras A, Punjabi NM. Quantifying ventilation by X-ray velocimetry in healthy adults. Respir Res 2023; 24:215. [PMID: 37649012 PMCID: PMC10469820 DOI: 10.1186/s12931-023-02517-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 08/18/2023] [Indexed: 09/01/2023] Open
Abstract
RATIONALE X-ray velocimetry (XV) has been utilized in preclinical models to assess lung motion and regional ventilation, though no studies have compared XV-derived physiologic parameters to measures derived through conventional means. OBJECTIVES To assess agreement between XV-analysis of fluoroscopic lung images and pitot tube flowmeter measures of ventilation. METHODS XV- and pitot tube-derived ventilatory parameters were compared during tidal breathing and with bilevel-assisted breathing. Levels of agreement were assessed using the Bland-Altman analysis. Mixed models were used to characterize the association between XV- and pitot tube-derived values and optimize XV-derived values for higher ventilatory volumes. MEASUREMENTS AND MAIN RESULTS Twenty-four healthy volunteers were assessed during tidal breathing and 11 were reassessed with increased minute ventilation with bilevel-assisted breathing. No clinically significant differences were observed between the two methods for respiratory rate (average Δ: 0.58; 95% limits of agreement: -1.55, 2.71) or duty cycle (average Δ: 0.02; 95% limits of agreement: 0.01, 0.03). Tidal volumes and flow rates measured using XV were lower than those measured using the pitot tube flowmeter, particularly at the higher volume ranges with bilevel-assisted breathing. Under these conditions, a mixed-model based adjustment was applied to the XV-derived values of tidal volume and flow rate to obtain closer agreement with the pitot tube-derived values. CONCLUSION Radiographically obtained measures of ventilation with XV demonstrate a high degree of correlation with parameters of ventilation. If the accuracy of XV were also confirmed for assessing the regional distribution of ventilation, it would provide information that goes beyond the scope of conventional pulmonary function tests or static radiographic assessments.
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Affiliation(s)
- Trishul Siddharthan
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, FL, USA.
| | - Kyle Grealis
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, FL, USA
| | | | | | | | - Alex Tombleson
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, FL, USA
| | - Molly Dalzell
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, FL, USA
| | - Ernesto Gonzalez
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, FL, USA
| | - Kinjal Bhatt Nakrani
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, FL, USA
| | | | - Michael G Lester
- Division of Allergy, Pulmonary, and Critical Care Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Bradley W Richmond
- Division of Allergy, Pulmonary, and Critical Care Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Veterans Affairs Medical Center, Nashville, TN, USA
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | | | - Naresh M Punjabi
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, FL, USA
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De Luca D, Lopez-Rodriguez E, Minucci A, Vendittelli F, Gentile L, Stival E, Conti G, Piastra M, Antonelli M, Echaide M, Perez-Gil J, Capoluongo ED. Clinical and biological role of secretory phospholipase A2 in acute respiratory distress syndrome infants. Crit Care 2013; 17:R163. [PMID: 23883784 PMCID: PMC4057254 DOI: 10.1186/cc12842] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 06/15/2013] [Accepted: 07/24/2013] [Indexed: 12/22/2022] Open
Abstract
INTRODUCTION Secretory phospholipase A2 is supposed to play a role in acute lung injury but no data are available for pediatric acute respiratory distress syndrome (ARDS). It is not clear which enzyme subtypes are secreted and what the relationships are between enzyme activity, biophysical and biochemical parameters, and clinical outcomes. We aimed to measure the enzyme and identify its subtypes and to study its biochemical and biophysical effect. The secondary aim was to correlate enzyme activity with clinical outcome. METHODS Bronchoalveolar lavage was performed in 24 infants with ARDS and 14 controls with no lung disease. Samples were assayed for secretory phospholipase A2 and molecules related to its activity and expression. Western blotting and captive bubble surfactometry were also performed. Clinical data were real time downloaded. RESULTS Tumor necrosis factor-α (814 (506-2,499) vs. 287 (111-1,315) pg/mL; P = 0.04), enzyme activity (430 (253-600) vs. 149 (61-387) IU/mL; P = 0.01), free fatty acids (4.3 (2.8-8.6) vs. 2 (0.8-4.6) mM; P = 0.026), and minimum surface tension (25.6 ± 6.1 vs. 18 ± 1.8 mN/m; P = 0.006) were higher in ARDS than in controls. Phospholipids are lower in ARDS than in controls (76.5 (54-100) vs. 1,094 (536-2,907) μg/mL; P = 0.0001). Three enzyme subtypes were identified (-IIA, -V, -X), although in lower quantities in controls; another subtype (-IB) was mainly detected in ARDS. Significant correlations exist between enzyme activity, free fatty acids (ρ = 0.823; P < 0.001), and surface tension (ρ = 0.55; P < 0.028). Correlations also exist with intensive care stay (ρ = 0.54; P = 0.001), PRISM-III24 (ρ = 0.79; P< 0.001), duration of ventilation (ρ = 0.53; P = 0.002), and oxygen therapy (ρ = 0.54; P = 0.001). CONCLUSIONS Secretory phospholipase A2 activity is raised in pediatric ARDS and constituted of four subtypes. Enzyme correlates with some inflammatory mediators, surface tension, and major clinical outcomes. Secretory phospholipase A2 may be a clinically relevant target in pediatric ARDS.
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Affiliation(s)
- Daniele De Luca
- Pediatric Intensive Care Unit, Dept of Anesthesiology and Intensive Care, University Hospital 'A. Gemelli', Catholic University of the Sacred Heart, L.go A. Gemelli 8, 00168 Rome, Italy
- Laboratory of Clinical Molecular Biology, Dept of Laboratory Medicine, University Hospital 'A. Gemelli', Catholic University of the Sacred Heart, L.go A. Gemelli 8, 00168 Rome, Italy
| | - Elena Lopez-Rodriguez
- Dept of Biochemistry, Faculty of Biology, Complutense University, av. Complutense s/n, 28040 Madrid, Spain
| | - Angelo Minucci
- Laboratory of Clinical Molecular Biology, Dept of Laboratory Medicine, University Hospital 'A. Gemelli', Catholic University of the Sacred Heart, L.go A. Gemelli 8, 00168 Rome, Italy
| | - Francesca Vendittelli
- Laboratory of Clinical Molecular Biology, Dept of Laboratory Medicine, University Hospital 'A. Gemelli', Catholic University of the Sacred Heart, L.go A. Gemelli 8, 00168 Rome, Italy
| | - Leonarda Gentile
- Laboratory of Clinical Molecular Biology, Dept of Laboratory Medicine, University Hospital 'A. Gemelli', Catholic University of the Sacred Heart, L.go A. Gemelli 8, 00168 Rome, Italy
| | - Eleonora Stival
- Pediatric Intensive Care Unit, Dept of Anesthesiology and Intensive Care, University Hospital 'A. Gemelli', Catholic University of the Sacred Heart, L.go A. Gemelli 8, 00168 Rome, Italy
| | - Giorgio Conti
- Pediatric Intensive Care Unit, Dept of Anesthesiology and Intensive Care, University Hospital 'A. Gemelli', Catholic University of the Sacred Heart, L.go A. Gemelli 8, 00168 Rome, Italy
| | - Marco Piastra
- Pediatric Intensive Care Unit, Dept of Anesthesiology and Intensive Care, University Hospital 'A. Gemelli', Catholic University of the Sacred Heart, L.go A. Gemelli 8, 00168 Rome, Italy
| | - Massimo Antonelli
- Pediatric Intensive Care Unit, Dept of Anesthesiology and Intensive Care, University Hospital 'A. Gemelli', Catholic University of the Sacred Heart, L.go A. Gemelli 8, 00168 Rome, Italy
| | - Mercedes Echaide
- Dept of Biochemistry, Faculty of Biology, Complutense University, av. Complutense s/n, 28040 Madrid, Spain
| | - Jesus Perez-Gil
- Dept of Biochemistry, Faculty of Biology, Complutense University, av. Complutense s/n, 28040 Madrid, Spain
| | - Ettore D Capoluongo
- Laboratory of Clinical Molecular Biology, Dept of Laboratory Medicine, University Hospital 'A. Gemelli', Catholic University of the Sacred Heart, L.go A. Gemelli 8, 00168 Rome, Italy
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Ewing-Bui D, Mink SN. Interdependence of flow between lobes reduces maximal emptying postresection in dogs. J Appl Physiol (1985) 2002; 92:100-8. [PMID: 11744648 DOI: 10.1152/jappl.2002.92.1.100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effect of pulmonary resection on the maximal emptying of the remaining lobes was examined in an open-chest preparation in normal canine lungs and in a unilobar papain emphysema model. The objectives were to determine whether, compared with when both lungs were deflated (BL), maximal emptying of the normal lower lobes or the emphysematous right lower lobe would be altered 1) when acute pneumonectomy of the contralateral lung was performed (OL) and 2) when the lower lobe deflated alone (LA). The alveolar capsule technique was used to measure alveolar pressures (Palv) at 75, 50, and 30% lobar vital capacity (VC). During forced deflation, the maximal rates of deflation (dPalv/dt) and flows (lobarV(max)) of the lower lobes were determined under the three different conditions. The Pitot-static tube technique was used to measure intrabronchial pressures and to estimate bronchial area and compliance in which values were obtained at the same central airway during the conditions studied. The results showed that, compared with BL and OL, dPalv/dt and lobar V(max) decreased during LA (P < 0.05). These findings were due to a reduction in bronchial area during LA that limited flow at a lower maximal value compared with BL. This decrease in area appeared to be due to a change in bronchial pressure area behavior that resulted in a smaller bronchial area during LA for similar transmural pressures between conditions. There were no differences in findings between normal and emphysematous lobes. This study suggested that removal of lobes may alter the pressure area behavior of central airways. Possible mechanisms considered were differences in axial tension between conditions, negative effort dependence, or parenchymal-bronchial interdependence that may be relevant to understanding the dynamic collapsibility of central as well as intraparenchymal airways.
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Affiliation(s)
- David Ewing-Bui
- Section of Thoracic Surgery, Department of Surgery, and Section of Respiratory Diseases, Department of Internal Medicine, University of Manitoba, Winnipeg, Manitoba, Canada R3E-0Z3
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Hotchkiss JR, Adams AB, Stone MK, Dries DJ, Marini JJ, Crooke PS. Oscillations and noise: inherent instability of pressure support ventilation? Am J Respir Crit Care Med 2002; 165:47-53. [PMID: 11779729 DOI: 10.1164/ajrccm.165.1.2101025] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Pressure support ventilation (PSV) is almost universally employed in the management of actively breathing ventilated patients with acute respiratory failure. In this partial support mode of ventilation, a fixed pressure is applied to the airway opening, and flow delivery is monitored by the ventilator. Inspiration is terminated when measured inspiratory flow falls below a set fraction of the peak flow rate (flow cutoff); the ventilator then cycles to a lower pressure and expiration commences. We used linear and nonlinear mathematical models to investigate the dynamic behavior of pressure support ventilation and confirmed the predicted behavior using a test lung. Our mathematical and laboratory analyses indicate that pressure support ventilation in the setting of airflow obstruction can be accompanied by marked variations in tidal volume and end-expiratory alveolar pressure, even when subject effort is unvarying. Unstable behavior was observed in the simplest plausible linear mathematical model and is an inherent consequence of the underlying dynamics of this mode of ventilation. The mechanism underlying the observed instability is "feed forward" behavior mediated by oscillatory elevation in end-expiratory pressure. In both mathematical and mechanical models, unstable behavior occurred at impedance values and ventilator settings that are clinically realistic.
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Affiliation(s)
- John R Hotchkiss
- Section of Pulmonary and Critical Care and Section of Surgery, Regions Hospital and University of Minnesota, St. Paul, Minnesota 55101, USA.
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Mink SN. Mechanism of lobar alveolar pressure decline during forced deflation in canine regional emphysema. J Appl Physiol (1985) 1997; 82:632-43. [PMID: 9049747 DOI: 10.1152/jappl.1997.82.2.632] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
A canine model of unilobar papain-induced emphysema was used to examine the extent to which differences in alveolar pressures (PA) would develop between an emphysematous right lower lobe (RLL) and normal left lower lobe (LLL) during forced vital capacity (FVC) deflation. RLL and LLL PA (PARLL and PALLL, respectively) were measured by the alveolar capsule technique. During forced deflation, PA and lobar flows were determined between 95 and 20% FVC. A choke point common to both lower lobes was observed at > 40% FVC. The results showed that deflation compliance (C) was altered for the RLL such that <90% lobar vital capacity, CRLL > CLLL, whereas >90% lobar vital capacity, CRLL < CLLL. At 95 and 90% FVC, the initial RLL PA decline was greater than that for the LLL (P < 0.05). However, large differences in PA were prevented because of the effect of interdependence of regional expiratory flow (IREF). IREF caused a relative decrease in RLL flows and increase in LLL flows that limited PA differences. Between 80 and 50% FVC, as CRLL became greater than CLLL, and because of the initial effect of IREF, PARLL was approximately PALLL. At < and = 40% FVC, without IREF, lobar differences in PA widened. These findings indicate that IREF may affect the dynamics of flow limitation in regional lung disease.
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Affiliation(s)
- S N Mink
- Section of Respiratory Diseases, University of Manitoba, Winnipeg, Canada
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Georgopoulos D, Mitrouska I, Markopoulou K, Patakas D, Anthonisen NR. Effects of breathing patterns on mechanically ventilated patients with chronic obstructive pulmonary disease and dynamic hyperinflation. Intensive Care Med 1995; 21:880-6. [PMID: 8636519 DOI: 10.1007/bf01712328] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE To examine the circulatory and respiratory effects of breathing pattern in patients with chronic obstructive pulmonary disease (COPD) and dynamic hyperinflation (DH) during controlled mechanical ventilation. DESIGN Prospective, controlled, randomized, non-blinded study. SETTING Respiratory intensive care unit of a university hospital. PATIENTS Nine patients with acute respiratory failure and DH due to acute exacerbations of COPD. INTERVENTIONS Keeping tidal volume and total breath duration (TTOT) constant, patients were ventilated at six different values of expiratory time (TE). TE changes were randomly induced by alterations of constant inspiratory flow (VI) and/or end-inspiratory pause (EIP). Patients were studied at three levels of VI(0.93 +/- 0.08, 0.72 +/- 0.06 and 0.55 +/- 0.04 l/s, mean +/- SE), with and without EIP (10% of TTOT). MEASUREMENTS AND RESULTS Lung volumes, airflows, airways pressures, oxygenation indices and dead space were measured. Alveolar pressure and airway resistance (Rmin), as well as the additional resistance (delta R) due to viscoelastic pressure dissipation and time-constant inequalities, were estimated by rapid airway occlusion during inflation. In seven out of nine patients, right-heart catheterization was performed and hemodynamic parameters were obtained at each value of TE. A significant decrease of intrinsic positive end-expiratory pressure (PEEPi), end-inspiratory static and mean (mPaw) airway pressures, end-expiratory lung volume above passive FRC (Vtrap), delta R and venous admixture and a significant increase of peak airway pressure, Rmin, stroke volume index and mixed venous PO2 (PvO2) were observed when VI increased. At each VI, the addition of EIP significantly decreased iso-volume expiratory flows and PvO2 and increased Vtrap and mPaw. CONCLUSIONS We conclude that in mechanically ventilated patients with COPD, the pattern of lung inflation and TE alteration have a significant impact on respiratory system mechanics, gas exchange and hemodynamics. Addition of EIP in patients with COPD may be detrimental.
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Affiliation(s)
- D Georgopoulos
- Respiratory Failure Unit, G. Papanicolaou Hospital, University of Thessaloniki, Exohi, Greece
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