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Bawua LK, Miaskowski C, Suba S, Badilini F, Mortara D, Hu X, Rodway GW, Hoffmann TJ, Pelter MM. Agreement between respiratory rate measurement using a combined electrocardiographic derived method versus impedance from pneumography. J Electrocardiol 2021; 71:16-24. [PMID: 35007832 DOI: 10.1016/j.jelectrocard.2021.12.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 12/15/2021] [Accepted: 12/20/2021] [Indexed: 10/19/2022]
Abstract
BACKGROUND Impedance pneumography (IP) is the current device-driven method used to measure respiratory rate (RR) in hospitalized patients. However, RR alarms are common and contribute to alarm fatigue. While RR derived from electrocardiographic (ECG) waveforms hold promise, they have not been compared to the IP method. PURPOSE Study examined the agreement between the IP and combined-ECG derived (EDR) for normal RR (≥12 or ≤20 breaths/minute [bpm]); low RR (≤5 bpm); and high RR (≥30 bpm). METHODOLOGY One-hundred intensive care unit patients were included by RR group: (1) normal RR (n = 50; 25 low RR and 25 high RR); (2) low RR (n = 50); and (3) high RR (n = 50). Bland-Altman analysis was used to evaluate agreement. RESULTS For normal RR, a significant bias difference of -1.00 + 2.11 (95% CI -1.60 to -0.40) and 95% limit of agreement (LOA) of -5.13 to 3.13 was found. For low RR, a significant bias difference of -16.54 + 6.02 (95% CI: -18.25 to -14.83) and a 95% LOA of -28.33 to - 4.75 was found. For high RR, a significant bias difference of 17.94 + 12.01 (95% CI: 14.53 to 21.35) and 95% LOA of -5.60 to 41.48 was found. CONCLUSION Combined-EDR method had good agreement with the IP method for normal RR. However, for the low RR, combined-EDR was consistently higher than the IP method and almost always lower for the high RR, which could reduce the number of RR alarms. However, replication in a larger sample including confirmation with visual assessment is warranted.
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Affiliation(s)
- Linda K Bawua
- School of Nursing, University of California, San Francisco, CA, USA.
| | | | - Sukardi Suba
- School of Nursing, University of Rochester, NY, USA.
| | - Fabio Badilini
- School of Nursing, University of California, San Francisco, CA, USA.
| | - David Mortara
- School of Nursing, University of California, San Francisco, CA, USA.
| | - Xiao Hu
- School of Nursing, Duke University Durham, NC, USA.
| | | | - Thomas J Hoffmann
- School of Nursing, University of California, San Francisco, CA, USA.
| | - Michele M Pelter
- School of Nursing, University of California, San Francisco, CA, USA.
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2
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Wright SP, Dawkins TG, Eves ND, Shave R, Tedford RJ, Mak S. Hemodynamic function of the right ventricular-pulmonary vascular-left atrial unit: normal responses to exercise in healthy adults. Am J Physiol Heart Circ Physiol 2020; 320:H923-H941. [PMID: 33356960 DOI: 10.1152/ajpheart.00720.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
With each heartbeat, the right ventricle (RV) inputs blood into the pulmonary vascular (PV) compartment, which conducts blood through the lungs at low pressure and concurrently fills the left atrium (LA) for output to the systemic circulation. This overall hemodynamic function of the integrated RV-PV-LA unit is determined by complex interactions between the components that vary over the cardiac cycle but are often assessed in terms of mean pressure and flow. Exercise challenges these hemodynamic interactions as cardiac filling increases, stroke volume augments, and cycle length decreases, with PV pressures ultimately increasing in association with cardiac output. Recent cardiopulmonary exercise hemodynamic studies have enriched the available data from healthy adults, yielded insight into the underlying mechanisms that modify the PV pressure-flow relationship, and better delineated the normal limits of healthy responses to exercise. This review will examine hemodynamic function of the RV-PV-LA unit using the two-element Windkessel model for the pulmonary circulation. It will focus on acute PV and LA responses that accommodate increased RV output during exercise, including PV recruitment and distension and LA reservoir expansion, and the integrated mean pressure-flow response to exercise in healthy adults. Finally, it will consider how these responses may be impacted by age-related remodeling and modified by sex-related cardiopulmonary differences. Studying the determinants and recognizing the normal limits of PV pressure-flow relations during exercise will improve our understanding of cardiopulmonary mechanisms that facilitate or limit exercise.
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Affiliation(s)
- S P Wright
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - T G Dawkins
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, Wales, United Kingdom
| | - N D Eves
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - R Shave
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan, Kelowna, British Columbia, Canada
| | - R J Tedford
- Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - S Mak
- Division of Cardiology, Department of Medicine, Sinai Health, Toronto, Ontario, Canada.,Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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3
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Su J, Hughes AD, Simonsen U, Nielsen-Kudsk JE, Parker KH, Howard LS, Mellemkjaer S. Impact of pulmonary endarterectomy on pulmonary arterial wave propagation and reservoir function. Am J Physiol Heart Circ Physiol 2019; 317:H505-H516. [PMID: 31225986 PMCID: PMC6703995 DOI: 10.1152/ajpheart.00181.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/29/2019] [Accepted: 06/17/2019] [Indexed: 01/09/2023]
Abstract
High wave speed and large wave reflection in the pulmonary artery have previously been reported in patients with chronic thromboembolic pulmonary hypertension (CTEPH). We assessed the impact of pulmonary endarterectomy (PEA) on pulmonary arterial wave propagation and reservoir function in patients with CTEPH. Right heart catheterization was performed using a combined pressure and Doppler flow sensor-tipped guidewire to obtain simultaneous pressure and flow velocity measurements in the pulmonary artery in eight patients with CTEPH before and 3 mo after PEA. Wave intensity and reservoir-excess pressure analyses were then performed. Following PEA, mean pulmonary arterial pressure (PAPm; ∼49 vs. ∼32 mmHg), pulmonary vascular resistance (PVR; ∼11.1 vs. ∼5.1 Wood units), and wave speed (∼16.5 vs. ∼8.1 m/s), i.e., local arterial stiffness, markedly decreased. The changes in the intensity of the reflected arterial wave and wave reflection index (pre: ∼28%; post: ∼22%) were small, and patients post-PEA with and without residual pulmonary hypertension (i.e., PAPm ≥ 25 mmHg) had similar wave reflection index (∼20 vs. ∼23%). The reservoir and excess pressure decreased post-PEA, and the changes were associated with improved right ventricular afterload, function, and size. In conclusion, although PVR and arterial stiffness decreased substantially following PEA, large wave reflection persisted, even in patients without residual pulmonary hypertension, indicating lack of improvement in vascular impedance mismatch. This may continue to affect the optimal ventriculoarterial interaction, and further studies are warranted to determine whether this contributes to persistent symptoms in some patients.NEW & NOTEWORTHY We performed wave intensity analysis in the pulmonary artery in patients with chronic thromboembolic pulmonary hypertension before and 3 mo after pulmonary endarterectomy. Despite substantial reduction in pulmonary arterial pressures, vascular resistance, and arterial stiffness, large pulmonary arterial wave reflection persisted 3 mo postsurgery, even in patients without residual pulmonary hypertension, suggestive of lack of improvement in vascular impedance mismatch.
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Affiliation(s)
- Junjing Su
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Alun D Hughes
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Ulf Simonsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Kim H Parker
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Luke S Howard
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Soren Mellemkjaer
- Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark
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4
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Su J, Manisty C, Simonsen U, Howard LS, Parker KH, Hughes AD. Pulmonary artery wave propagation and reservoir function in conscious man: impact of pulmonary vascular disease, respiration and dynamic stress tests. J Physiol 2017; 595:6463-6476. [PMID: 28816352 DOI: 10.1113/jp274385] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 08/14/2017] [Indexed: 01/09/2023] Open
Abstract
KEY POINTS Wave travel plays an important role in cardiovascular physiology. However, many aspects of pulmonary arterial wave behaviour remain unclear. Wave intensity and reservoir-excess pressure analyses were applied in the pulmonary artery in subjects with and without pulmonary hypertension during spontaneous respiration and dynamic stress tests. Arterial wave energy decreased during expiration and Valsalva manoeuvre due to decreased ventricular preload. Wave energy also decreased during handgrip exercise due to increased heart rate. In pulmonary hypertension patients, the asymptotic pressure at which the microvascular flow ceases, the reservoir pressure related to arterial compliance and the excess pressure caused by waves increased. The reservoir and excess pressures decreased during Valsalva manoeuvre but remained unchanged during handgrip exercise. This study provides insights into the influence of pulmonary vascular disease, spontaneous respiration and dynamic stress tests on pulmonary artery wave propagation and reservoir function. ABSTRACT Detailed haemodynamic analysis may provide novel insights into the pulmonary circulation. Therefore, wave intensity and reservoir-excess pressure analyses were applied in the pulmonary artery to characterize changes in wave propagation and reservoir function during spontaneous respiration and dynamic stress tests. Right heart catheterization was performed using a pressure and Doppler flow sensor tipped guidewire to obtain simultaneous pressure and flow velocity measurements in the pulmonary artery in control subjects and patients with pulmonary arterial hypertension (PAH) at rest. In controls, recordings were also obtained during Valsalva manoeuvre and handgrip exercise. The asymptotic pressure at which the flow through the microcirculation ceases, the reservoir pressure related to arterial compliance and the excess pressure caused by arterial waves increased in PAH patients compared to controls. The systolic and diastolic rate constants also increased, while the diastolic time constant decreased. The forward compression wave energy decreased by ∼8% in controls and ∼6% in PAH patients during expiration compared to inspiration, while the wave speed remained unchanged throughout the respiratory cycle. Wave energy decreased during Valsalva manoeuvre (by ∼45%) and handgrip exercise (by ∼27%) with unaffected wave speed. Moreover, the reservoir and excess pressures decreased during Valsalva manoeuvre but remained unaltered during handgrip exercise. In conclusion, reservoir-excess pressure analysis applied to the pulmonary artery revealed distinctive differences between controls and PAH patients. Variations in the ventricular preload and afterload influence pulmonary arterial wave propagation as demonstrated by changes in wave energy during spontaneous respiration and dynamic stress tests.
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Affiliation(s)
- Junjing Su
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.,National Heart and Lung Institute, Imperial College London, London, UK
| | - Charlotte Manisty
- Institute of Cardiovascular Science, University College London, London, UK
| | - Ulf Simonsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Luke S Howard
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Kim H Parker
- Department of Bioengineering, Imperial College London, London, UK
| | - Alun D Hughes
- National Heart and Lung Institute, Imperial College London, London, UK.,Institute of Cardiovascular Science, University College London, London, UK
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5
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Ghimire A, Andersen MJ, Burrowes LM, Bouwmeester JC, Grant AD, Belenkie I, Fine NM, Borlaug BA, Tyberg JV. The reservoir-wave approach to characterize pulmonary vascular-right ventricular interactions in humans. J Appl Physiol (1985) 2016; 121:1348-1353. [DOI: 10.1152/japplphysiol.00697.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/03/2016] [Accepted: 10/19/2016] [Indexed: 01/08/2023] Open
Abstract
Using the reservoir-wave approach (RWA) we previously characterized pulmonary vasculature mechanics in a normal canine model. We found reflected backward-traveling waves that decrease pressure and increase flow in the proximal pulmonary artery (PA). These waves decrease right ventricular (RV) afterload and facilitate RV ejection. With pathological alterations to the pulmonary vasculature, these waves may change and impact RV performance. Our objective in this study was to characterize PA wave reflection and the alterations in RV performance in cardiac patients, using the RWA. PA pressure, Doppler-flow velocity, and pulmonary arterial wedge pressure were measured in 11 patients with exertional dyspnea. The RWA was employed to analyze PA pressure and flow; wave intensity analysis characterized PA waves. Wave-related pressure was partitioned into two components: pressures due to forward-traveling and to backward-traveling waves. RV performance was assessed by examining the work done in raising reservoir pressure and that associated with the wave components of systolic PA pressure. Wave-related work, the mostly nonrecoverable energy expended by the RV to eject blood, tended to vary directly with mean PA pressure. Where PA pressures were lower, there were pressure-decreasing/flow-increasing backward waves that aided RV ejection. Where PA pressures were higher, there were pressure-increasing/flow-decreasing backward waves that impeded RV ejection. Pressure-increasing/flow-decreasing backward waves were responsible for systolic notches in the Doppler flow velocity profiles in patients with the highest PA pressure. Pulmonary hypertension is characterized by reflected waves that impede RV ejection and an increase in wave-related work. The RWA may facilitate the development of therapeutic strategies.
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Affiliation(s)
- Anukul Ghimire
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, and the Libin Institute of Cardiovascular Research, Calgary, Alberta, Canada
| | - Mads J. Andersen
- Department of Cardiology, University of Aarhus, Aarhus, Denmark; and
- Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic Rochester, Rochester, Minnesota
| | - Lindsay M. Burrowes
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, and the Libin Institute of Cardiovascular Research, Calgary, Alberta, Canada
| | - J. Christopher Bouwmeester
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, and the Libin Institute of Cardiovascular Research, Calgary, Alberta, Canada
| | - Andrew D. Grant
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, and the Libin Institute of Cardiovascular Research, Calgary, Alberta, Canada
| | - Israel Belenkie
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, and the Libin Institute of Cardiovascular Research, Calgary, Alberta, Canada
| | - Nowell M. Fine
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, and the Libin Institute of Cardiovascular Research, Calgary, Alberta, Canada
| | - Barry A. Borlaug
- Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic Rochester, Rochester, Minnesota
| | - John V. Tyberg
- Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, and the Libin Institute of Cardiovascular Research, Calgary, Alberta, Canada
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Abstract
The circulation of the lung is unique both in volume and function. For example, it is the only organ with two circulations: the pulmonary circulation, the main function of which is gas exchange, and the bronchial circulation, a systemic vascular supply that provides oxygenated blood to the walls of the conducting airways, pulmonary arteries and veins. The pulmonary circulation accommodates the entire cardiac output, maintaining high blood flow at low intravascular arterial pressure. As compared with the systemic circulation, pulmonary arteries have thinner walls with much less vascular smooth muscle and a relative lack of basal tone. Factors controlling pulmonary blood flow include vascular structure, gravity, mechanical effects of breathing, and the influence of neural and humoral factors. Pulmonary vascular tone is also altered by hypoxia, which causes pulmonary vasoconstriction. If the hypoxic stimulus persists for a prolonged period, contraction is accompanied by remodeling of the vasculature, resulting in pulmonary hypertension. In addition, genetic and environmental factors can also confer susceptibility to development of pulmonary hypertension. Under normal conditions, the endothelium forms a tight barrier, actively regulating interstitial fluid homeostasis. Infection and inflammation compromise normal barrier homeostasis, resulting in increased permeability and edema formation. This article focuses on reviewing the basics of the lung circulation (pulmonary and bronchial), normal development and transition at birth and vasoregulation. Mechanisms contributing to pathological conditions in the pulmonary circulation, in particular when barrier function is disrupted and during development of pulmonary hypertension, will also be discussed.
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Affiliation(s)
- Karthik Suresh
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Larissa A. Shimoda
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
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7
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Baykan AO, Gür M, Acele A, Şeker T, Yüksel Kalkan G, Şahin DY, Koc M, Bulut A, Harbalıoğlu H, Caylı M. Both Systemic and Pulmonary Artery Stiffness Predict Ventricular Functional Recovery after Successful Percutaneous Closure of Atrial Septal Defects in Adults. CONGENIT HEART DIS 2015; 11:144-54. [PMID: 26556671 DOI: 10.1111/chd.12302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/28/2015] [Indexed: 11/30/2022]
Abstract
BACKGROUND Percutaneous closure of atrial septal defect (ASD) has become the preferred method in treatment of the majority of cases. The aim of this study was to evaluate the echocardiographic effects of percutaneous closure of secundum ASD in adults and assess which parameters predict good response to closure. DESIGN We prospectively included 42 patients with secundum ASD treated successfully with percutaneous device closure. All patients underwent transthoracic echocardiography examination with tissue Doppler imaging before, 24 hours after and within 3 months of intervention. Measurements of arterial stiffness were carried out using a Mobil-O-Graph arteriography system. RESULTS Remodeling of heart chambers occurred immediately and persisted at 3 months after ASD closure. Significant decreases were observed in right ventricle (RV) end-diastolic diameter, right atrium volume index, and tricuspid annular plane systolic excursion both after the procedure and at 3 months (P < .01 for all). The RV and left ventricle (LV) tissue Doppler-myocardial performance index demonstrated to decline during follow up (P = .0001). Significant correlations were found between pulse-wave velocity, augmentation index, pulmonary artery stiffness, and LV-RV tissue Doppler-myocardial performance index at third month. Linear regression analyses showed that pulse-wave velocity is the most effective parameter of LV and pulmonary artery stiffness is the most effective parameter of RV functional recovery, respectively, assessed by tissue Doppler-myocardial performance index. CONCLUSIONS Percutaneous closure of secundum ASD in adults has various sustained benefits on multiple echocardiographic parameters within 3 months. The changes in RV and LV function after device closure were significantly correlated with the degree of pulmonary artery stiffness and pulse-wave velocity, respectively.
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Affiliation(s)
- Ahmet Oytun Baykan
- Department of Cardiology, Adana Numune Training and Research Hospital, Adana, Turkey
| | - Mustafa Gür
- Department of Cardiology, Adana Numune Training and Research Hospital, Adana, Turkey.,Department of Cardiology, Kafkas University School of Medicine, Kars, Turkey
| | - Armağan Acele
- Department of Cardiology, Adana Numune Training and Research Hospital, Adana, Turkey
| | - Taner Şeker
- Department of Cardiology, Adana Numune Training and Research Hospital, Adana, Turkey
| | - Gülhan Yüksel Kalkan
- Department of Cardiology, Adana Numune Training and Research Hospital, Adana, Turkey
| | - Durmuş Yıldıray Şahin
- Department of Cardiology, Adana Numune Training and Research Hospital, Adana, Turkey
| | - Mevlüt Koc
- Department of Cardiology, Adana Numune Training and Research Hospital, Adana, Turkey
| | - Atilla Bulut
- Department of Cardiology, Adana Numune Training and Research Hospital, Adana, Turkey
| | - Hazar Harbalıoğlu
- Department of Cardiology, Adana Numune Training and Research Hospital, Adana, Turkey
| | - Murat Caylı
- Department of Cardiology, Adana Numune Training and Research Hospital, Adana, Turkey.,Department of Cardiology, Dicle University School of Medicine, Diyarbakır, Turkey
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8
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Tyberg JV, Bouwmeester JC, Burrowes LM, Parker KH, Shrive NG, Wang JJ. A new teaching model of the systemic circulation that incorporates reservoir characteristics. Artery Res 2015. [DOI: 10.1016/j.artres.2015.02.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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9
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Bouwmeester JC, Belenkie I, Shrive NG, Tyberg JV. Genesis of the characteristic pulmonary venous pressure waveform as described by the reservoir-wave model. J Physiol 2014; 592:3801-12. [PMID: 25015922 DOI: 10.1113/jphysiol.2014.272963] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Conventional haemodynamic analysis of pulmonary venous and left atrial (LA) pressure waveforms yields substantial forward and backward waves throughout the cardiac cycle; the reservoir wave model provides an alternative analysis with minimal waves during diastole. Pressure and flow in a single pulmonary vein (PV) and the main pulmonary artery (PA) were measured in anaesthetized dogs and the effects of hypoxia and nitric oxide, volume loading, and positive-end expiratory pressure (PEEP) were observed. The reservoir wave model was used to determine the reservoir contribution to PV pressure and flow. Subtracting reservoir pressure and flow resulted in 'excess' quantities which were treated as wave-related.Wave intensity analysis of excess pressure and flow quantified the contributions of waves originating upstream (from the PA) and downstream (from the LA and/or left ventricle (LV)).Major features of the characteristic PV waveform are caused by sequential LA and LV contraction and relaxation creating backward compression (i.e.pressure-increasing) waves followed by decompression (i.e. pressure-decreasing) waves. Mitral valve opening is linked to a backwards decompression wave (i.e. diastolic suction). During late systole and early diastole, forward waves originating in the PA are significant. These waves were attenuated less with volume loading and delayed with PEEP. The reservoir wave model shows that the forward and backward waves are negligible during LV diastasis and that the changes in pressure and flow can be accounted for by the discharge of upstream reservoirs. In sharp contrast, conventional analysis posits forward and backward waves such that much of the energy of the forward wave is opposed by the backward wave.
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Affiliation(s)
| | - Israel Belenkie
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada Department of Cardiac Sciences, University of Calgary, Calgary, Alberta, Canada Department of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Nigel G Shrive
- Department of Civil Engineering, University of Calgary, Calgary, Alberta, Canada
| | - John V Tyberg
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada Department of Cardiac Sciences, University of Calgary, Calgary, Alberta, Canada Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
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Bouwmeester JC, Belenkie I, Shrive NG, Tyberg JV. Wave reflections in the pulmonary arteries analysed with the reservoir-wave model. J Physiol 2014; 592:3053-62. [PMID: 24756638 DOI: 10.1113/jphysiol.2014.273094] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Conventional haemodynamic analysis of pressure and flow in the pulmonary circulation yields incident and reflected waves throughout the cardiac cycle, even during diastole. The reservoir-wave model provides an alternative haemodynamic analysis consistent with minimal wave activity during diastole. Pressure and flow in the main pulmonary artery were measured in anaesthetized dogs and the effects of hypoxia and nitric oxide, volume loading and positive end-expiratory pressure were observed. The reservoir-wave model was used to determine the reservoir contribution to pressure and flow and once subtracted, resulted in 'excess' quantities, which were treated as wave-related. Wave intensity analysis quantified the contributions of waves originating upstream (forward-going waves) and downstream (backward-going waves). In the pulmonary artery, negative reflections of incident waves created by the right ventricle were observed. Overall, the distance from the pulmonary artery valve to this reflection site was calculated to be 5.7 ± 0.2 cm. During 100% O2 ventilation, the strength of these reflections increased 10% with volume loading and decreased 4% with 10 cmH2O positive end-expiratory pressure. In the pulmonary arterial circulation, negative reflections arise from the junction of lobar arteries from the left and right pulmonary arteries. This mechanism serves to reduce peak systolic pressure, while increasing blood flow.
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Affiliation(s)
| | - Israel Belenkie
- Libin Cardiovascular Institute of Alberta Departments of Cardiac Sciences Medicine
| | | | - John V Tyberg
- Libin Cardiovascular Institute of Alberta Departments of Cardiac Sciences Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
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11
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Smailys A, Mitchell JR, Doig CJ, Tyberg JV, Belenkie I. High-frequency oscillatory ventilation versus conventional ventilation: hemodynamic effects on lung and heart. Physiol Rep 2014; 2:e00259. [PMID: 24760513 PMCID: PMC4002239 DOI: 10.1002/phy2.259] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Abstract High-frequency oscillatory ventilation (HFOV) may improve gas exchange in patients who are inadequately ventilated by conventional mechanical ventilation (CV); however, the hemodynamic consequences of switching to HFOV remain unclear. We compared the effects of CV and HFOV on pulmonary vascular conductance and left ventricular (LV) preload and performance at different airway and filling pressures. In anesthetized dogs, we measured LV dimensions, aortic and pulmonary artery (PA) flow, and mean airway ( AW) and pericardial pressures. Catheter-tip pressure manometers measured aortic, LV, left atrial, and PA pressures. The pericardium and chest were closed. At LV end-diastolic pressure (PLVED) = 5 mmHg and 12 mmHg, PEEP was varied (6 cm H2O, 12 cm H2O, and 18 cm H2O) during CV. Then, at airway pressures equal to those during CV, HFOV was applied at 4 Hz, 10 Hz, and 15 Hz. Increased AW decreased pulmonary vascular conductance. As cardiac output increased, conductance increased. At PLVED = 12 mmHg, conductance was greatest during HFOV at 4 Hz. LV preload (i.e., ALV, our index of end-diastolic volume) was similar during HFOV and CV for all conditions. At PLVED = 12 mmHg, SWLV was similar during CV and HFOV, but, at PLVED = 5 mmHg and AW 10 cm H2O, SWLV was lower during HFOV than CV. Compared to pulmonary vascular conductance at higher frequencies, at PLVED = 12 mmHg, conductance was greater at HFOV of 4 Hz. Effects of CV and HFOV on LV preload and performance were similar except for decreased SWLV at PLVED = 5 mmHg. These observations suggest the need for further studies to assess their potential clinical relevance.
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Affiliation(s)
- Andrea Smailys
- Department of Cardiac Sciences, University of Calgary, Calgary, Alberta, Canada
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