Ventilation-perfusion mismatch

Due to its ability to induce heterogenous, patient-specific damage in pulmonary alveoli and capillaries, COVID-19 poses challenges in defining a uniform profile to elucidate infection across all patients. Computational models that integrate changes in ventilation and perfusion with heterogeneous damage profiles offer valuable insights into the impact of COVID-19 on pulmonary health. This study aims to develop an in silico hypothesis-testing platform specifically focused on studying microvascular pulmonary perfusion in COVID-19-infected lungs...

RATIONALE: Blood flow rate affects mixed venous oxygenation (SvO2 ) during venovenous extracorporeal membrane oxygenation (ECMO), with possible effects on the pulmonary circulation and the right heart function. OBJECTIVES: We aimed at describing the physiologic effects of different levels of SvO2 obtained by changing ECMO blood flow, in patients with severe ARDS receiving ECMO and controlled mechanical ventilation. METHODS: Low (SvO2 target 70-75%), intermediate (SvO2 target 75-80%) and high (SvO2 target > 80%) ECMO blood flows were applied for 30 minutes in random order in 20 patients...

BACKGROUND: Measuring arterial partial pressure of carbon dioxide (PaCO2 ) is crucial for proper mechanical ventilation, but the current sampling method is invasive. End-tidal carbon dioxide (EtCO2 ) has been used as a surrogate, which can be measured non-invasively, but its limited accuracy is due to ventilation-perfusion mismatch. This study aimed to develop a non-invasive PaCO2 estimation model using machine learning. METHODS: This retrospective observational study included pediatric patients (< 18 years) admitted to the pediatric intensive care unit of a tertiary children's hospital and received mechanical ventilation between January 2021 and June 2022...

Ventilation-perfusion matching occurs passively and is also actively regulated through hypoxic pulmonary vasoconstriction (HPV). The extent of HPV activity in humans, particularly normal subjects is uncertain. Current evaluation of HPV assesses changes in ventilation-perfusion relationships/pulmonary vascular resistance with hypoxia and are invasive, or unsuitable for patients because of safety concerns. We used a non-invasive imaging-based approach to quantify the pulmonary vascular response to oxygen as a metric of HPV by measuring perfusion changes between breathing 21% and 30%O2 using arterial spin labeling (ASL) MRI...

Chest trauma is one of the most serious and difficult injuries, with various complications that can lead to ventilation-perfusion (V/Q) mismatch and systemic hypoxia. We are presenting a case of a 53-year-old male with no chronic therapy who was admitted to the Intensive Care Unit due to severe respiratory failure after chest trauma. He developed a right-sided pneumothorax, and then a thoracic drain was placed. On admission, the patient was hemodynamically unstable and tachypneic. He was intubated and mechanically ventilated, febrile (38...

PURPOSE: Ventilation Perfusion SPECT is important in the diagnostics of e.g. pulmonary embolism and chronic obstructive pulmonary disease. Classical and reverse mismatched defects can be identified by utilizing the ventilation-perfusion ratio. Unfortunately, this ratio is only linear in the ventilation, the scale is not symmetrical regarding classical and reversed mismatches and small perfusion values give rise to artifacts. The ventilation-perfusion (VQ) difference is developed as an alternative...

INTRODUCTION: The mechanism of post-traumatic brain injury (TBI) hypoxemia involves ventilation/perfusion mismatch and loss of pulmonary hypoxic vasoconstriction. Inhaled nitric oxide (iNO) has been studied as an adjunct treatment to avoid the use of high positive end-expiratory pressure and inspired oxygen in treatment-refractory hypoxia. We hypothesized that iNO treatment following TBI would improve systemic and cerebral oxygenation via improved matching of pulmonary perfusion and ventilation...

An air leak is a pathologic communication between an area of the endobronchial tree and the pleural space, causing continued air flow. The communication can originate from a distal portion of the airway, causing an alveolar-pleural fistula, or from a more proximal airway, causing a bronchopleural fistula. When the air leak persists beyond 5-7 days, it is classified as persistent air leak (PAL). PAL has serious implications on patient management and outcomes, such as prolonged chest tube maintenance, high rate of infections, ventilation-perfusion mismatch, and prolonged hospital stay with higher morbidity and mortality...

BACKGROUND: Pulmonary air embolism (AE) and thromboembolism lead to severe ventilation-perfusion defects. The spatial distribution of pulmonary perfusion dysfunctions differs substantially in the two pulmonary embolism pathologies, and the effects on respiratory mechanics, gas exchange, and ventilation-perfusion match have not been compared within a study. Therefore, we compared changes in indices reflecting airway and respiratory tissue mechanics, gas exchange, and capnography when pulmonary embolism was induced by venous injection of air as a model of gas embolism or by clamping the main pulmonary artery to mimic severe thromboembolism...

BACKGROUND: Prone position is used in acute respiratory distress syndrome and in coronavirus disease 2019 (Covid-19) acute respiratory distress syndrome (ARDS). However, physiological mechanisms remain unclear. The aim of this study was to determine whether improved oxygenation was related to pulmonary shunt fraction (Q's/Q't), alveolar dead space (Vd/Vtalv) and ventilation/perfusion mismatch (V'A /Q'). METHODS: This was an international, prospective, observational, multicenter, cohort study, including six intensive care units in Sweden and Poland and 71 mechanically ventilated adult patients...

Congenital severe peripheral pulmonary artery stenosis is usually associated with pulmonary atresia, ventricular septal defect and major aortopulmonary collateral artery. Complications mainly related to respiratory system frequently occur after peripheral pulmonary artery patch augmentation with or without uniforcalization. Pulmonary hemorrhage and airway bleeding can be fatal. Airway compression from surrounding structures such as reconstructed central pulmonary artery, pulmonary hypertension, ventilation/perfusion mismatch, and pulmonary ischemia reperfusion injury are also life-threating complications...

PURPOSE: The lung is a unique organ with a ventilation-perfusion mismatch, which can cause inhomogeneous incidence rates of lung cancer depending on the location in the lung. We aimed to evaluate the incidence of lung adenocarcinoma in each lobe by analyzing the incidence per unit volume, to evaluate the incidence without being affected by differences in the size of each lobe or in the size of the lungs between individuals. METHODS: The number of adenocarcinomas in each lobe was counted...

BACKGROUND: Prone position has been shown to improve oxygenation and survival in patients with early acute respiratory distress syndrome (ARDS). These beneficial effects are partly mediated by improved ventilation/perfusion (V/Q) distribution. Few studies have investigated the impact of early versus delayed proning on V/Q distribution in patients with ARDS. The aim of this study was to assess the regional ventilation and perfusion distribution in early versus persistent ARDS after prone position...

BACKGROUND: Pulmonary endarterectomy (PEA) is the treatment of choice for patients with chronic thromboembolic pulmonary hypertension (CTEPH) with accessible lesions. Breathing pure oxygen (hyperoxia) during right heart catheterization (RHC) allows for the calculation of the right-to-left shunt fraction (Qs/Qt). In the absence of intracardiac shunt, Qs/Qt can be used as a marker of ventilation-perfusion mismatch in patients with CTEPH. This study involved investigating Qs/Qt after PEA and its relation to other disease-specific outcomes...

PURPOSE: Pulmonary emboli (PE) contribute substantially to coronavirus disease 2019 (COVID-19) related mortality and morbidity. Immune cell-mediated hyperinflammation drives the procoagulant state in COVID-19 patients, resulting in immunothrombosis. To study the role of peripheral blood mononuclear cells (PBMC) in the procoagulant state of COVID-19 patients, we performed a functional bioassay and related outcomes to the occurrence of PE. Secondary aims were to relate this functional assay to plasma D-dimer levels, ventilation perfusion mismatch and TF expression on monocyte subsets...

BACKGROUND: Surgical intervention for lung resection can cause ventilation-perfusion mismatches and affect gas exchange; however, minimally invasive assessment of blood flow is difficult. This study aimed to evaluate changes in pulmonary blood flow after radical lung cancer surgery using a minimally invasive dynamic digital chest radiography system. METHODS: We evaluated 64 patients who underwent radical lobectomies. Postoperative changes in pulmonary blood flow, assessed using dynamic chest radiography-based blood flow ratios (BFRs), were compared with the temporal evolution of both functional lung volumes (FLVs) and estimated lung weight (ELW) derived from computed tomography (CT) volumetry...

Acute respiratory distress syndrome (ARDS) is a pulmonary pathology that itself can harm and further lead to many other significant hazardous sequelae. Pulmonary vasculature can be distressed by several diseases, but among all the causes, sepsis is one of the main culprits. Its consequences include significant alveolar injury, refractory hypoxemia, ventilation-perfusion mismatch, and destruction of the alveolar-capillary membrane. Dyspnea with diffuse infiltration on a chest X-ray is the most prevalent clinical symptom...

Recent advances in imaging analysis have enabled evaluation of ventilation and perfusion in specific regions by chest computed tomography (CT) and magnetic resonance imaging (MRI), in addition to modalities including dynamic chest radiography, scintigraphy, positron emission tomography (PET), ultrasound, and electrical impedance tomography (EIT). In this review, an overview of current functional imaging techniques is provided for each modality. Advances in chest CT have allowed for the analysis of local volume changes and small airway disease in addition to emphysema, using the Jacobian determinant and parametric response mapping with inspiratory and expiratory images...

We aimed to follow a nationwide cohort of patients with pulmonary embolism (PE) without any exclusions to generate information regarding long-term symptoms, investigational findings and to determine the prevalence of chronic thromboembolic pulmonary hypertension (CTEPH). We hypothesized that this approach would yield generalizable estimates of CTEPH prevalence and incidence. All individuals diagnosed with acute PE in Sweden in 2005 were identified using the National Patient Register. In 2007, survivors were asked to complete a questionnaire regarding current symptoms...

We have investigated the elimination of inert gases in the lung during the elimination of nitrous oxide (N2 O) using a two-step mathematical model that allows the contribution from net gas volume expansion, which occurs in Step 2, to be separated from other factors. When a second inert gas is used in addition to N2 O, the effect on that gas appears as an extra volume of the gas eliminated in association with the dilution produced by N2 O washout in Step 2. We first considered the effect of elimination in a single gas-exchanging unit under steady-state conditions and then extended our analysis to a lung having a log-normal distribution of ventilation and perfusion...