Pulmonary Blood Volume Research Articles

Pulmonary Blood Volume Measured by Dual-Energy Computed Tomography Can Help Distinguish Patients With Pulmonary Hypertension.

PurposeTo evaluate the correlation between whole lung enhancement (WLE) and pulmonary blood volume (PBV) obtained through dual energy computed tomography pulmonary angiography (DECTPA) and echocardiography-derived systolic pulmonary arterial pressure (SPAP).MethodsSixty-eight patients who underwent DECTPA were enrolled in the study after giving informed consent. A transthoracic echocardiography was performed for all the subjects within 48 h of their DECTPA study to measure SPAP. The correlation of the two DECTPA-derived parameters, WLE and PBV, with SPAP was assessed. In addition, the predictive strength of these parameters was compared with that of traditional computed tomography (CT) signs of pulmonary hypertension (PH).ResultsThe SPAP value showed a moderate correlation with main pulmonary artery (MPA) diameter (r = 0.48, P < 0.001), while having a weak correlation with WLE (r = −0.33, P = 0.007), PBV (r = −0.31, P = 0.01) and MPA/ascending aorta (MPA/AA) ratio (r = 0.26, P = 0.03). On regression analysis, MPA diameter (B ± SE: 1.8 ± 0.6, P = 0.004) and WLE (B ± SE: −0.5 ± 0.3, P = 0.042) had significant association with SPAP. In addition, SPAP ≥30 mmHg was related to the right to left ventricular diameter (RV/LV) ratio [OR (CI 95%): 24.39 (1.3–573.2), P = 0.04] and reversely associated with PBV [OR (CI 95%): 0.96 (0.93–0.98), P = 0.005]. Acquired cutoff value of 83% for PBV showed sensitivity and specificity of 73% to identify SPAP ≥30 mmHg [AUC (CI 95%):0.727 (0.588–0.866), P = 0.008].ConclusionsAutomated postprocessing calculation of iodine distribution analysis by DECTPA could be considered as an adjunctive tool to investigate for PH.

First-pass perfusion cardiovascular magnetic resonance parameters as surrogate markers for left ventricular diastolic dysfunction: a validation against cardiac catheterization

The non-invasive assessment of left ventricular (LV) diastolic dysfunction remains a challenge. The role of first-pass perfusion cardiac magnetic resonance (CMR) parameters in quantitative hemodynamic analyses has been reported. We therefore aimed to validate the diagnostic ability and accuracy of such parameters against cardiac catheterization for LV diastolic dysfunction in patients with left heart disease (LHD). We retrospectively enrolled 77 LHD patients who underwent CMR imaging and cardiac catheterization. LV diastolic dysfunction was defined as pulmonary capillary wedge pressure (PCWP) or LV end-diastolic pressure (LVEDP) > 12 mmHg on catheterization. On first-pass perfusion CMR imaging, pulmonary transit time (PTT) was measured as the time for blood to pass from the left ventricle to the right ventricle (RV) through the pulmonary vasculature. Pulmonary transit beat (PTB) was the number of cardiac cycles within the interval, and pulmonary blood volume indexed to body surface area (PBVi) was the product of PTB and RV stroke volume index (RVSVi). Of the 77 LHD patients, 53 (68.83%) were found to have LV diastolic dysfunction, and showed significantly higher PTTc, PTB, and PBVi (p < 0.05) compared with those without. In multivariate analyses, only PTTc and PTB were identified as independent predictors of LV diastolic dysfunction (p < 0.05). With an optimal cutoff of 11.9 s, PTTc yielded the best diagnostic performance for LV diastolic dysfunction (area under the curve = 0.83, p < 0.001). PTTc may represent a non-invasive quantitative surrogate marker for the detection and assessment of diastolic dysfunction in LHD patients. • PTTc yielded the best diagnostic accuracy for diastolic dysfunction, with an optimal cutoff of 11.9 s, and a specificity of 100%. • PTTc and PTB were found to be independent predictors of LV diastolic dysfunction across different multivariate models with high reproducibility. • PTTc is a promising non-invasive surrogate marker for the detection and assessment of diastolic dysfunction in LHD patients.

Chest CT Findings in Hospitalized Patients with SARS-CoV-2: Delta versus Omicron Variants.

BackgroundCT manifestations of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) may differ among variants.PurposeTo compare the chest CT findings of SARS-CoV-2 between the Delta and Omicron variants.Materials and MethodsThis retrospective study collected consecutive baseline chest CT images of hospitalized patients with SARS-CoV-2 from a secondary referral hospital when the Delta and Omicron variants predominated. Two radiologists categorized CT images based on the Radiological Society of North America classification system for coronavirus disease 2019 (COVID-19) and visually graded pneumonia extent. Pneumonia, pleural effusion, and intrapulmonary vessels were segmented and quantified on CT images using a priori developed neural networks, followed by reader confirmation. Multivariable logistic and linear regression analyses were performed to examine the associations between the variants and CT category, distribution, severity, and peripheral vascularity.ResultsIn total, 88 patients with the Delta (mean age, 67 years±15; 46 men) and 88 patients with the Omicron (mean age, 62 years±19; 51 men) variants were included. Omicron was associated with a less frequent typical peripheral, bilateral ground-glass opacity (32% [28/88] versus 57% [50/88]; P=.001), more frequent peri-bronchovascular predilection (38% [25/66] versus 7% [5/71]; P<.001), lower visual pneumonia extent (5.4±6.0 versus 7.7±6.6; P=.02), similar pneumonia volume (5%±10 versus 7%±11; P=.14), and a higher proportion of vessels with a cross-sectional area smaller than 5 mm2 relative to the total pulmonary blood volume (BV5%; 48%±11 versus 44%±8; P=.004). In adjusted analyses, Omicron was associated with a non-typical appearance (odds ratio, 0.34; P=.006), peri-bronchovascular predilection (odds ratio, 9.2; P<.001), and higher BV5% (β value, 3.8; P=.01) but similar visual pneumonia extent (P=.17) and pneumonia volume (P=.67) relative to Delta variant.ConclusionsOn chest CT, the Omicron SARS-COV-2 variant showed nontypical, peri-bronchovascular pneumonia and less pulmonary vascular involvement than the Delta variant in hospitalized patients with comparable CT disease severity.

Sex-Specific Physiological Responses to Ultramarathon.

Despite a growing body of literature on the physiological responses to ultramarathon, there is a paucity of data in females. This study assessed the female physiological response to ultramarathon and compared the frequency of perturbations to a group of race- and time-matched males. Data were collected from 53 contestants of an ultramarathon trail race at the Ultra-Trail du Mont-Blanc (UTMB®) in 2018/19. Before and within 2 h of the finish, participants underwent physiological assessments, including blood sampling for biomarkers (creatine kinase-MB isoenzyme [CK-MB], cardiac troponin I [cTnI], brain natriuretic peptide [BNP], and creatinine [Cr]), pulmonary function testing (spirometry, exhaled NO, diffusing capacities, and mouth pressures), and transthoracic ultrasound (lung comet tails, cardiac function). Data from eight female finishers (age = 36.6 ± 6.9 yr; finish time = 30:57 ± 11:36 h:min) were compared with a group of eight time-matched males (age = 40.3 ± 8.3 yr; finish time = 30:46 ± 10:32 h:min). Females exhibited significant pre- to postrace increases in BNP (25.8 ± 14.6 vs 140.9 ± 102.7 pg·mL -1 ; P = 0.007) and CK-MB (3.3 ± 2.4 vs 74.6 ± 49.6 IU·L -1 ; P = 0.005), whereas males exhibited significant pre- to postrace increases in BNP (26.6 ± 17.5 vs 96.4 ± 51.9 pg·mL -1 ; P = 0.002), CK-MB (7.2 ± 3.9 vs 108.8 ± 37.4 IU·L -1 ; P = 0.002), and Cr (1.06 ± 0.19 vs 1.23 ± 0.24 mg·dL -1 ; P = 0.028). Lung function declined in both groups, but males exhibited additional reductions in lung diffusing capacities (DL CO = 34.4 ± 5.7 vs 29.2 ± 6.9 mL⋅min -1 ⋅mm Hg -1 , P = 0.004; DL NO = 179.1 ± 26.2 vs 152.8 ± 33.4 mL⋅min -1 ⋅mm Hg -1 , P = 0.002) and pulmonary capillary blood volumes (77.4 ± 16.7 vs 57.3 ± 16.1 mL; P = 0.002). Males, but not females, exhibited evidence of mild postrace pulmonary edema. Pooled effect sizes for within-group pre- to postrace changes, for all variables, were generally larger in males versus females ( d = 0.86 vs 0.63). Ultramarathon negatively affects a range of physiological functions but generally evokes more frequent perturbations, with larger effect sizes, in males compared to females with similar race performances.

HEMODYNAMIC STATUS OF PATIENTS WITH DIFFERENT VARIANTS OF ISCHEMIC HEART DISEASE COMORBIDITY BEFORE AND AFTER CORONARY BYPASS GRAFTING

TYPE: Abstract TOPIC: Cardiothoracic Surgery PURPOSE: Assessment of systemic and pulmonary hemodynamic for IHD patients with various comorbidity before and after CABG by transpulmonary thermodilution method. METHODS: 46 IHD patients were examined and divided into three groups based on comorbidity: cardiovascular, respiratory and metabolic. Parameters were recorded by transpulmonary thermodilution using «Pulsion Picco Plus» module of Drager Delta XL monitor (Germany) at 3 stages: after initiation of controlled mechanical ventilation (stage I), after CPB procedure completion (stage II) and after 24 hours surgery (stage III). RESULTS: In the group with respiratory comorbidity after CPB withdrawal and after 24 hours CABG, the highest level of systemic vascular resistance (2359.67 [2125.91; 2593.42] and 2294 [2070.7; 2517.3] dyne / sec / cm-5 / m2) were measured, moreover the minimum global ejection fraction values (18 [15; 22] and 19 [16; 21]%), and less noticeable (in relation to other patients groups) decreasion of global end-diastolic and pulmonary blood volumes. During all three stages, the maximum values of EVLWI and PVPI were recorded for patients with respiratory and metabolic comorbidity. Hemodynamic status disorders during follow-up dynamics were less pronounced for the patients with cardiovascular comorbidity. CONCLUSIONS: Volumetric and hemodynamic monitoring makes it possible to comprehensively assess the central and pulmonary circulation indicators for patients with coronary artery disease and various variants of comorbidity during operational and early postoperative periods dynamics. CLINICAL IMPLICATIONS: to develop a personalized approach to treatment and significantly improve the prognosis of morbidity DISCLOSURE: Nothing to declare. KEYWORD: CORONARY BYPASS GRAFTING

Assessment of the Budesonid Protective Effects in Patients with Cardio-Respiratory Comorbidity During Coronary Bypassing with Artificial Circulation

The objective: evaluation of the effect of budesonide and low-volume mechanical ventilation (LVMV) on pulmonary volemia, oxygen transport and respiratory biomechanics in patients with concurrent ischemic heart disease (IHD) and chronic obstructive pulmonary disease (COPD) during coronary artery bypass grafting (CABG) with artificial circulation (AC).Subjects and Methods. 50 patients with concurrent IHD and COPD were enrolled in the study. During AC, patients of Group I (20 people) received mechanical ventilation with the peak inspiratory pressure of 15 mbar, tidal volume of 3‒4 ml/kg, positive end-expiratory pressure of 5 mbar in combination with inhalation of nebulized budesonide. In Group II (30 people), the similar isolated respiratory support was provided. Pulmonary blood volume, indices of extravascular lung water (EVLW), pulmonary vascular permeability (PVPI), oxygen delivery (DO2I) and consumption (VO2I), oxygen extraction ratio (O2ER), pulmonary shunt fraction (Qs/Qt), oxygenation index were determined. The study consisted of 3 stages: before AC, after its completion and one day after CABG.Results. Before CABG, the EVLW index in all patients exceeded the standard level by 67‒72%. After weaning from AC, it decreased by 23% in Group I and by 8% in Group II. In patients receiving budesonide, PVPI significantly decreased after artificial circulation, while in patients from Group II, it remained unchanged. DO2I and O2ER in all patients were within the reference range, and VO2I was below it with a minimum value in Group II after weaning from AC. In this cohort, the Qs/Qt level was significantly higher, while OI was lower versus patients from Group I. Among patients who received budesonide immediately after AC and 2 hours after it, pulmonary resistance decreased while lung compliance increased. In Group II, those parameters changed oppositely. In Group I, one case of hydrothorax was recorded, and in Group II, 2 patients were diagnosed with polysegmental pneumonia and 2 patients – with pneumothorax. The median duration of mechanical ventilation in the postoperative period made 220 minutes in Group I, and 290 minutes in Group II (p = 0.018).Conclusion. In patients with concurrent IHD and COPD, use of the combination of low-volume mechanical ventilation and inhalation of nebulized budesonide during AC stabilizes the volemic status of the lungs, improves the oxygenating function and respiratory biomechanics in the postperfusion and early postoperative periods of CABG.

A-55 | Peripheral Pulmonary Blood Volume Decreases in Patients with Intermediate Risk Acute Pulmonary Embolism Treated with Anticoagulation

Ultrasound-facilitated, catheter-directed fibrinolysis has been shown to increase peripheral pulmonary arterial blood volume distribution at 48 hours post-treatment as a mechanism for right ventricular (RV) recovery in intermediate risk pulmonary embolism (PE). The change in peripheral pulmonary blood volume distribution in patients receiving anticoagulation monotherapy remains unclear.

Quantitative assessment of regional pulmonary perfusion using three-dimensional ultrafast dynamic contrast-enhanced magnetic resonance imaging: pilot study results in 10 patients

Background. Currently there is a high demand in reliable noninvasive diagnostic technique assessing the physiological parameters of the lungs. We are exploring the three-dimensional ultrafast MRI sequence as a novel diagnostic modality allowing the assessment of regional quantitative perfusion parameters in pulmonary tissue.&#x0D; Aim. To assess regional differences in quantitative pulmonary perfusion parameters in 10 volunteers with no evidence of interstitial lung disease by computed tomography, clinical, and laboratory data.&#x0D; Materials and methods. 10 volunteers with no signs of interstitial lung disease were examined by three-dimensional ultrafast dynamic contrast-enhanced MR imaging using 3D T1-weighted images. The values of pulmonary blood flow (PBF), mean transit time (MTT), and pulmonary blood volume (PBV) for the targeted regions of interest were calculated based on the dynamic image series. For calculations, arterial input function (AIF) was used, as well as the time-intensity curves.&#x0D; Results. The values of PBF, MTT, and PBV showed statistically significant differences between central and peripheral sections of lungs. Provided model can be implemented for quantitative assessment of regional pulmonary perfusion allows it to be used to determine the reliability of PBF, MTT and PBV values.&#x0D; Conclusions. Three-dimensional ultrafast MRI sequence is a novel diagnostic modality allowing the assessment of regional quantitative pulmonary perfusion parameters in pulmonary tissue, regardless of physiological features of blood supply mechanisms in different lung regions.

Perspectives on the Structure and Function of the Avian Respiratory System: Functional Efficiency Built on Structural Complexity

Among the air-breathing vertebrates, regarding respiratory efficiency, the avian respiratory system rests at the evolutionary zenith. Structurally, it is separated into a lung that serves as a gas exchanger and air sacs that mechanically ventilate the lung continuously and unidirectionally in a caudocranial direction. Largely avascular, the air sacs are delicate, transparent, compliant and capacious air-filled spaces that are not meaningfully involved in gas exchange. The avian lungs are deeply and firmly attached to the vertebrae and the ribs on the dorsolateral aspects, rendering them practically rigid and inflexible. The attachment of the lung to the body wall allowed extreme subdivision of the exchange tissue into minuscule and stable terminal respiratory units, the air capillaries. The process generated a large respiratory surface area in small lungs with low volume density of gas exchange tissue. For the respiratory structures, invariably, thin blood-gas barrier, large respiratory surface area and large pulmonary capillary blood volume are the foremost adaptive structural features that confer large total pulmonary morphometric diffusing capacities of O2. At parabronchial level, the construction and the arrangement of the airway- and the vascular components of the avian lung determine the delivery, the presentation and the exposure of inspired air to capillary blood across the blood-gas barrier. In the avian lung, crosscurrent-, countercurrent- and multicapillary serial arterialization systems that stem from the organization of the structural parts of the lung promote gas exchange. The exceptional respiratory efficiency of the avian respiratory system stems from synergy of morphological properties and physiological processes, means by which O2uptake is optimized and high metabolic states and capacities supported. Given that among the extant animal taxa insects, birds and bats (which accomplished volancy chronologically in that order) possess structurally much different respiratory systems, the avian respiratory system was by no means a prerequisite for evolution of powered flight but was but one of the adaptive solutions to realization of an exceptionally efficient mode of locomotion.

Pulmonary Capillary Recruitment Is Attenuated Post Left Ventricular Assist Device Implantation

Intoduction There is limited knowledge of pulmonary physiology and pulmonary function following continuous flow-left ventricular assist device (CF-LVAD) implantation. Therefore, the present study investigated if CF-LVAD influenced the pulmonary circulation by assessing pulmonary capillary blood volume and alveolar- capillary conductance as well as pulmonary function in heart failure patients. Methods 17 patients with severe HF who were scheduled for CF-LVAD (Heart Mate II® or Heart Ware®) implantation participated in the study. They underwent pulmonary function testing (measures of lung volumes and flow rates) and more unique measures of pulmonary physiology using a rebreathe-technique that quantified the diffusing capacity of the lungs for carbon monoxide and nitric oxide (DLCO and DLNO, respectively) pre and 3 months post CF-LVAD implantation. Results After CF-LVAD, pulmonary function was not significantly changed (p>0.05). For lung diffusing capacity, DLCO was significantly reduced (p=0.04), however, alveolar volume (VA) was not changed (p=0.47). After DLCO was corrected by VA, DLCO/VA demonstrated a trend towards reduction (p=0.08). For the alveolar-capillary component, capillary blood volume (Vc) and alveolar membrane conductance (Dm) were significantly or trended towards a reduction (p<0.04, p=0.06, respectively). However, Dm/Vc was not altered (p=0.92). Conclusions Early post CF LVAD implantation, Vc is reduced likely as a result of pulmonary capillary de-recruitment which contributes to the fall in lung diffusing capacity. There is limited knowledge of pulmonary physiology and pulmonary function following continuous flow-left ventricular assist device (CF-LVAD) implantation. Therefore, the present study investigated if CF-LVAD influenced the pulmonary circulation by assessing pulmonary capillary blood volume and alveolar- capillary conductance as well as pulmonary function in heart failure patients. 17 patients with severe HF who were scheduled for CF-LVAD (Heart Mate II® or Heart Ware®) implantation participated in the study. They underwent pulmonary function testing (measures of lung volumes and flow rates) and more unique measures of pulmonary physiology using a rebreathe-technique that quantified the diffusing capacity of the lungs for carbon monoxide and nitric oxide (DLCO and DLNO, respectively) pre and 3 months post CF-LVAD implantation. After CF-LVAD, pulmonary function was not significantly changed (p>0.05). For lung diffusing capacity, DLCO was significantly reduced (p=0.04), however, alveolar volume (VA) was not changed (p=0.47). After DLCO was corrected by VA, DLCO/VA demonstrated a trend towards reduction (p=0.08). For the alveolar-capillary component, capillary blood volume (Vc) and alveolar membrane conductance (Dm) were significantly or trended towards a reduction (p<0.04, p=0.06, respectively). However, Dm/Vc was not altered (p=0.92). Early post CF LVAD implantation, Vc is reduced likely as a result of pulmonary capillary de-recruitment which contributes to the fall in lung diffusing capacity.

Differential diagnosis of acute pulmonary embolism using contrast echocardiography.

Acute pulmonary embolism (aPE) leads to a significant decrease in antegrade pulmonary blood volume (PBV), which can be measured by contrast echocardiography at the bedside. The aim of this work was to evaluate the feasibility and performance of PBV differentiating between patients with and without aPE. A total of 89 patients underwent computed tomography pulmonary angiography (CTPA) for suspected aPE were enrolled in the study. Their clinical and conventional echocardiographic characteristics were collected. Contrast echocardiography with measurements of PBV were performed. There were 57 patients with aPE, with a mean Mastora pulmonary artery obstruction index (PAOI) of 56.14%. Pulmonary transit time (PTT), normalized PTT (nPTT) and PBV in patients with aPE was less than one half of those in patients without PE (p<0.05). There was significant negative correlation between PBV and Mastora PAOI (r=-0.897, p<0.01). None of the conventional echocardiographic parameters had an area under the receiver operating characteristic curve of >0.5, while it was 0.997(0.984~1.010) for PBV in differentiating between patients with aPE or not. The optimal cutoff valueof PBV was 370ml, with a sensitivity of 100%, a specificity of 95.45% and an accuracy of 96.55%. PBV had a powerful performance in differentiating between patients with aPE or not, and a PBV of <370ml indicated aPE. Contrast echocardiography is enormously useful in the recognition and differentiation of PE and can assess the severity of the PE and the patient's response to therapy.

Why Pulmonary Vasodilation May Be Part of a Key Strategy to Improve Survival in COVID-19.

Oxygenation is a function of both ventilation and perfusion. While approaches to the treatment of COVID-19 have focused largely on ventilation strategies and antiviral therapies, attention towards the improvement of vascular perfusion defects has been neglected. This article examines clinical findings that indicate perfusion defects are a critical component of COVID-19 pathophysiology. They also support the notion that medications that promote perfusion with pulmonary vasodilatation can yield significantly improved outcomes that include overall survival.Calcium channel blocker usage has been associated with improved survival and outcomes in several retrospective reviews of patient populations with COVID-19 from across the world. This includes studies conducted in Paris, France; Wuhan, China; Daegu, South Korea; Brooklyn, New York; Brussels, Belgium; and a national sample from across the United States. These medications are generally prescribed to treat hypertension. Yet, they are also utilized in various pulmonary conditions to effectuate pulmonary vasodilatation. Thus, a concomitant benefit appears to have been revealed as patients that were taking these medications had significantly improved overall survival. Sildenafil is another medication that induces pulmonary vasodilatation. It was found to decrease the need for mechanical ventilation and reduce hospital length of stay in COVID-19 in a triple-blinded randomized control trial.The importance of pulmonary vasodilation in COVID-19 has been evaluated further. In a study of over 100 high-resolution CT scans, patients with COVID-19 showed a significant reduction in pulmonary blood volume contained in small blood vessels of <5 mm2 compared to healthy volunteers. Moreover, this was found to clinically correlate with a need for more oxygen supplementation. In radiologic perfusion studies, hypoperfusion was observed to occur in the healthy lung while hyperperfusion was present in non-healthy COVID-inflicted lung. It appears that perfusion of oxygen-carrying capacity, in the form of hemoglobin-carrying red blood cells, is being misappropriated towards unhealthy lung tissue. This was observed concurrently while the healthy lung had a paucity of perfusion. This can be a key aspect of hypoxic development in COVID-19. Mathematical modeling of perfusion abnormalities in COVID-19 has also implicated extensive perfusion defects, with ventilation-perfusion mismatching in the non-injured lung and hyperperfusion of up to threefold increases to afflicted regions. Vasodilation in the form of systemic intravascular medications may help improve outcomes by resetting this imbalance and by promoting perfusion of the alveolar-capillary unit where gas exchange and oxygenation occurs particularly in the non-injured lung.Furthermore, endothelialitis and microthrombosis have been observed on pathology specimens as many patients develop micro-thrombi following prolonged perfusion deficits. Vasodilatory agents can curb vasoconstriction and drive more perfusion towards healthy tissue. The temporal matching of consistent systemic intravascular vasodilation therapy throughout the gradual and progressive course of the illness may be integral to achieving improved outcomes. Improving perfusion to healthy tissue can help improve oxygenation and overall outcomes in COVID-19. These findings support further utilization and investigation of vasodilatory agents in the treatment of COVID-19.

Do alterations in pulmonary vascular tone result in changes in central blood volumes? An experimental study

BackgroundThe effects of selective pulmonary vascular tone alterations on cardiac preload have not been previously examined. Therefore, we evaluated whether changing pulmonary vascular tone either by hypoxia or the inhalation of aerosolized prostacyclin (PGI2) altered intrathoracic or pulmonary blood volume (ITBV, PBV, respectively), both as surrogate for left ventricular preload. Additionally, the mean systemic filling pressure analogue (Pmsa) and pressure for venous return (Pvr) were calculated as surrogate of right ventricular preload.MethodsIn a randomized controlled animal study in 6 spontaneously breathing dogs, pulmonary vascular tone was increased by controlled moderate hypoxia (FiO2 about 0.10) and decreased by aerosolized PGI2. Also, inhalation of PGI2 was instituted to induce pulmonary vasodilation during normoxia and hypoxia. PBV, ITBV and circulating blood volume (Vdcirc) were measured using transpulmonary thermo-dye dilution. Pmsa and Pvr were calculated post hoc. Either the Wilcoxon-signed rank test or Friedman ANOVA test was performed.ResultsDuring hypoxia, mean pulmonary artery pressure (PAP) increased from median [IQR] 12 [8–15] to 19 [17–25] mmHg (p < 0.05). ITBV, PBV and their ratio with Vdcirc remained unaltered, which was also true for Pmsa, Pvr and cardiac output. PGI2 co-inhalation during hypoxia normalized mean PAP to 13 (12–16) mmHg (p < 0.05), but left cardiac preload surrogates unaltered. PGI2 inhalation during normoxia further decreased mean PAP to 10 (9–13) mmHg (p < 0.05) without changing any of the other investigated hemodynamic variables.ConclusionsIn spontaneously breathing dogs, changes in pulmonary vascular tone altered PAP but had no effect on cardiac output, central blood volumes or their relation to circulating blood volume, nor on Pmsa and Pvr. These observations suggest that cardiac preload is preserved despite substantial alterations in right ventricular afterload.

Effect of nitroglycerin on splanchnic and pulmonary blood volume

BackgroundSublingual nitroglycerin (SL NTG) is useful for treating acute decompensated heart failure, possibly by increasing splanchnic capacitance and reducing left ventricular (LV) preload. We evaluated a radionuclide method to study these effects, initially in subjects without heart failure. Methods and ResultsRed blood cells were labelled by an in vitro method. Abdominal and chest images were obtained at rest, showing relative regional blood volumes. The abdomen was then re-imaged during progressive escalation of intrathoracic pressure using continuous positive airway pressure to assess baseline splanchnic capacitance (pressure-volume relationship, PVR) and compliance (slope of PVR). The procedure was repeated after 0.6 mg SL NTG, followed by chest images. Relative splanchnic blood volume increased at rest after SL NTG (P < .002), signifying an increase in splanchnic capacitance. The slope of the splanchnic PVR decreased in proportion to the baseline PVR (P = .0014), signifying increased compliance. The relative pulmonary blood volume decreased in proportion to the increase in splanchnic blood volume (P = .01). ConclusionsA semi-quantitative radionuclide method demonstrated the effect of SL NTG for increasing splanchnic capacitance and compliance, with a proportional decrease in pulmonary blood volume. These data may be applied to quantitatively evaluate the importance of splanchnic vasodilation as a mechanism of LV preload reduction in the treatment of heart failure.Clinical Trials Registration: NCT02425566.

Dual-Energy Lung Perfusion in Portal Venous Phase CT-A Comparison with the Pulmonary Arterial Phase.

Pulmonary arterial dual-energy (aDE) CT is an established technique for evaluating pulmonary perfusion blood volume (PBV). As DECT protocols are increasingly used for thoraco-abdominal CT, this study assessed image quality and clinical findings in portal–venous phase dual-energy (vDE) CT and compared it to aDE. In 95 patients, vDE-CT was performed using a dual-source scanner (70/Sn150 kV, 560/140 ref.mAs). Pulmonary triggered aDE-CT served as reference (n = 94). PBV was reconstructed using a dedicated algorithm. Mean relative attenuation was measured in the pulmonary trunk, aorta, and segmented lung parenchyma. A distribution ratio (DL) between vessels and parenchyma was calculated to assess the iodine uptake of the lung parenchyma. Subjective overall diagnostic image quality was assessed for PBV images on a five-point Likert scale. Image artifacts were classified into five groups based on scale rating and compared between vDE and aDE. Pathological findings were correlated with the anatomical image datasets. Mean relative attenuation of the lung parenchyma was comparable in both groups (vDE: 23 ± 6 HU and aDE: 22 ± 7 HU), but significantly lower in the vessels of vDE. Therefore, iodine uptake of the lung parenchyma was significantly higher in vDE (DL: 10% vs. 8%, p < 0.01). The subjective overall image quality of the PBV images was comparable (p = 0.5). Rotation and streak artifacts were found in most of the patients (>86%, both p > 0.6). Dual-source artifacts were found in only a few patients in both groups (vDE 5%, aDE 7%, p = 0.5). Recess and subpleural artifacts were increased in vDE (vDE 53/27%, aDE 24/7%, both p < 0.001). Pathological findings were found in 19% of the vDE patients and 59% of the aDE patients. Comparable objective and subjective image quality of lung perfusion can be obtained in vDE and aDE. Iodine uptake of the lung parenchyma is increased in vDE compared to aDE, suggesting an interstitial pooling effect. Knowledge of the different appearances of artifacts will aid in the interpretation of the images. Additional clinical information about the lung parenchyma can be provided by PBV evaluation in vDE.

Hemodynamic status of patients with different comorbidities of ischemic heart disease before and after coronary artery bypass grafting

Aim. To assess the hemodynamic status by transpulmonary thermodilution (TPTD) in patients with ischemic heart disease (IHD) with different comorbidities before and after coronary artery bypass grafting (CABG).Materials and methods. 66 patients with IHD (40 men and 26 women) aged 53 to 77 years who were admitted for planned CABG were examined. The patients were divided into three groups according to the comorbidity: cardiovascular, respiratory, and metabolic. The first comorbidity was represented by a combination of IHD and multifocal atherosclerosis, the second – by IHD and chronic obstructive pulmonary disease (COPD), and the third – by IHD and metabolic syndrome (MS). All patients underwent CABG with the use of cardiopulmonary bypass. Hemodynamic parameters were recorded by the TPTD method using the Pulsion Picco Plus module (Germany) at 3 stages: after the start of mechanical ventilation (stage I), after the completion of cardiopulmonary bypass (stage II), and 24 hours after CABG (stage III).Results. The patients with IHD with different comorbidities differed in characteristic signs of hemodynamic changes. In IHD with comorbid COPD, after withdrawal from the cardiopulmonary bypass and 24 hours after CABG, the highest index of systemic vascular resistance, the minimum values of the global ejection fraction, and a decrease in the global end-diastolic volume and pulmonary blood volume less noticeable compared with other groups of patients were noted. With comorbid respiratory and metabolic disorders, the maximum values for the indices of extravascular lung water and pulmonary vascular permeability were recorded. In the patients with a comorbid cardiovascular disease, hemodynamic and volume status violations in the dynamic follow-up were less pronounced.Conclusion. The use of the TPTD method in patients with IHD before and after CABG makes it possible to specify the functional state of the circulatory system in different comorbidities, which increases the effectiveness of risk stratification and the accuracy of predicting possible complications.

Development of lung diffusion to adulthood following extremely preterm birth.

BackgroundGas exchange in extremely preterm (EP) infants must take place in fetal lungs. Childhood lung diffusing capacity of the lung for carbon monoxide (DLCO) is reduced; however, longitudinal development has not been investigated. We describe the growth of DLCO and its subcomponents to adulthood in EP compared with term-born subjects.MethodsTwo area-based cohorts born at gestational age ≤28 weeks or birthweight ≤1000 g in 1982–1985 (n=48) and 1991–1992 (n=35) were examined twice, at ages 18 and 25 years and 10 and 18 years, respectively, and compared with matched term-born controls. Single-breath DLCO was measured at two oxygen pressures, with subcomponents (membrane diffusion (DM) and pulmonary capillary blood volume (VC)) calculated using the Roughton–Forster equation.ResultsAge-, sex- and height-standardised transfer coefficients for carbon monoxide (KCO) and DLCO were reduced in EP compared with term-born subjects, and remained so during puberty and early adulthood (p-values for all time-points and both cohorts ≤0.04), whereas alveolar volume (VA) was similar. Development occurred in parallel to term-born controls, with no signs of pubertal catch-up growth nor decline at age 25 years (p-values for lack of parallelism within cohorts 0.99, 0.65, 0.71, 0.94 and 0.44 for z-DLCO, z-VA, z-KCO, DM and VC, respectively). Split by membrane and blood volume components, findings were less clear; however, membrane diffusion seemed most affected.ConclusionsPulmonary diffusing capacity was reduced in EP compared with term-born subjects, and development from childhood to adulthood tracked in parallel to term-born subjects, with no signs of catch-up growth nor decline at age 25 years.

Quantification of pulmonary perfusion abnormalities using DCE-MRI in COPD: comparison with quantitative CT and pulmonary function

ObjectivesPulmonary perfusion abnormalities are prevalent in patients with chronic obstructive pulmonary disease (COPD), are potentially reversible, and may be associated with emphysema development. Therefore, we aimed to evaluate the clinical meaningfulness of perfusion defects in percent (QDP) using DCE-MRI.MethodsWe investigated a subset of baseline DCE-MRIs, paired inspiratory/expiratory CTs, and pulmonary function testing (PFT) of 83 subjects (age = 65.7 ± 9.0 years, patients-at-risk, and all GOLD groups) from one center of the “COSYCONET” COPD cohort. QDP was computed from DCE-MRI using an in-house developed quantification pipeline, including four different approaches: Otsu’s method, k-means clustering, texture analysis, and 80th percentile threshold. QDP was compared with visual MRI perfusion scoring, CT parametric response mapping (PRM) indices of emphysema (PRMEmph) and functional small airway disease (PRMfSAD), and FEV1/FVC from PFT.ResultsAll QDP approaches showed high correlations with the MRI perfusion score (r = 0.67 to 0.72, p < 0.001), with the highest association based on Otsu’s method (r = 0.72, p < 0.001). QDP correlated significantly with all PRM indices (p < 0.001), with the strongest correlations with PRMEmph (r = 0.70 to 0.75, p < 0.001). QDP was distinctly higher than PRMEmph (mean difference = 35.85 to 40.40) and PRMfSAD (mean difference = 15.12 to 19.68), but in close agreement when combining both PRM indices (mean difference = 1.47 to 6.03) for all QDP approaches. QDP correlated moderately with FEV1/FVC (r = − 0.54 to − 0.41, p < 0.001).ConclusionQDP is associated with established markers of disease severity and the extent corresponds to the CT-derived combined extent of PRMEmph and PRMfSAD. We propose to use QDP based on Otsu’s method for future clinical studies in COPD.Key Points• QDP quantified from DCE-MRI is associated with visual MRI perfusion score, CT PRM indices, and PFT.• The extent of QDP from DCE-MRI corresponds to the combined extent of PRMEmph and PRMfSAD from CT.• Assessing pulmonary perfusion abnormalities using DCE-MRI with QDP improved the correlations with CT PRM indices and PFT compared to the quantification of pulmonary blood flow and volume.

Exercise hyperventilation and pulmonary gas exchange in chronic thromboembolic pulmonary hypertension: Effects of balloon pulmonary angioplasty

Excessive ventilation (V̇E) and abnormal gas exchange during exercise are features of chronic thromboembolic pulmonary hypertension (CTEPH). In selected CTEPH patients, balloon pulmonary angioplasty (BPA) improves symptoms and exercise capacity. How BPA affects exercise hyperventilation and gas exchange is poorly understood. In this longitudinal observational study, symptom-limited cardiopulmonary exercise tests and carbon monoxide lung diffusion (DLCO) were performed before and after BPA (interval, mean (SD): 3.1 (2.4) months) in 36 CTEPH patients without significant cardiac and/or pulmonary comorbidities. Peak work rate improved by 20% after BPA whilst V̇E at peak did not change despite improved ventilatory efficiency (lower V̇E with respect to CO2 output [V̇CO2]). At the highest identical work rate pre- and post-BPA (75 (30) watts), V̇E and alveolar-arterial oxygen gradient (P(Ai-a)O2) decreased by 17% and 19% after BPA, respectively. The physiological dead space fraction of tidal volume (VD/VT), calculated from measurements of arterial and mixed expired CO2, decreased by 20%. In the meantime, DLCO did not change. The best correlates of P(Ai-a)O2 measured at peak exercise were physiological VD/VT before BPA and DLCO after BPA. Ventilatory efficiency, physiological VD/VT, and pulmonary gas exchange improved after BPA. The fact that DLCO did not change suggests that the pulmonary capillary blood volume and probably the true alveolar dead space were unaffected by BPA. The correlation between DLCO measured before BPA and P(Ai-a)O2 measured after BPA suggests that DLCO may provide an easily accessible marker to predict the response to BPA in terms of pulmonary gas exchange.

SIMULATION OF THE RELATIONSHIP BETWEEN EXERCISE AND CARDIOPULMONARY FUNCTION AT HIGH ALTITUDE

ABSTRACT Introduction: Due to various uncertain and unexpected factors in life such as diseases, natural disasters, traffic accidents, and congenital disabilities, the number and proportion of lower limb amputations are still rising for many reasons, so the research on lower limb prostheses is particularly important. Objective: This work aimed to study the relationship between altitude exercise and cardiopulmonary function. Methods: A model of abnormal changes in cardiopulmonary function was established, and then 40 plateau exercisers were selected, all of whom arrived in Tibet in March 2017. The relationship between pulmonary circulation volume and internal pressure in the chest was observed and compared. The relationship between cardiopulmonary sensory reflex and exercise (high altitude) breathing and heart rate was analyzed. A comparison of the cardiopulmonary function of subjects of different genders was implemented. Moreover, the influence of different altitudes on the subjects’ cardiopulmonary function and the subjects’ cardiopulmonary function changes before departure and during the first, second, and third week after departure were observed and compared. Results: I. As the pressure in the thoracic cavity increased, the subjects’ pulmonary circulation blood volume gradually decreased, and the decrease was most obvious in the stage of thoracic pressure −50 to 0. II. As the cardiorespiratory reflex coefficient increased, the subjects’ breathing and heart rate compensatory acceleration appeared. III. Tracking and monitoring of the subjects’ cardiopulmonary indicators revealed that with the increase in altitude, the subjects’ average arterial pressure, respiratory frequency, and heart rate all showed an upward trend, while the blood oxygen saturation value showed a downward trend. IV. No matter how high the altitude was, the average arterial pressure, respiratory rate, and heart rate monitored of the subjects under exercise were significantly superior to the indicator values under resting state. In contrast, the blood oxygen saturation value showed the opposite trend. V. The subjects’ average arterial pressure, respiration, and heart rate in the first week were higher than other periods, but the blood oxygen saturation was relatively lower. In the second and third weeks, the changes in cardiopulmonary function were relatively smooth (all P&lt;0.05). VI. The changes in the index of the cardiopulmonary function of subjects of different genders were small (p&gt;0.05). Conclusion: Through modeling, the results of the plateau environment on the cardiopulmonary function of the body were made clearer, and these research data provided theoretical references for the training of the sports field in the plateau area. Level of evidence II; Therapeutic studies - investigation of treatment results.