View clinical trials related to Ventilation Perfusion Mismatch.
Filter by:Lung perfusion scintigraphy with 99mTc-MAA and ventilation scintigraphy with Technegas (V/Q SPECT/CT) has been the cornerstone for the detection of pulmonary embolisms (PE) for many decades. In last two decades after the introduction of pulmonary CTA, general PE detection has shifted towards CTA and V/Q SPECT/CT has become the modality of choice for specific patient populations (iodine contrast allergy, poor kidney function, pregnancy, etc.) or indications (pre-operative risk stratification, chronic embolism detection, pulmonary hypertension). V/Q SPECT/CT acquisition is performed on a gamma camera, but this technique has distinct challenges and/or disadvantages. A potential alternative is the nowadays broadly available. 68Ga as a positron emitter allows PET/CT imaging. Replacing 99mTc with 68Ga in both MAA and aerosol suspension is easy and requires no modifications. However, 68Ga-V/Q with PET/CT will resolve many of the disadvantages of V/Q SPECT/CT. International studies have proven safety and feasibility of replacing 99mTc with 68Ga and preliminary work by international colleagues and our institute have shown validated preparations of the radiopharmaceuticals. However, in our institution, clinical translation is hampered by lack of data on technical acquisition parameters for our scanners. The aim of this small study is to get more insights into technical parameters for image acquisition, logistical feasibility of V/Q PET/CT, and confirm preliminary non-inferiority of this new technique over the current clinical standard (V/Q SPECT/CT).
Patients with ARDS often suffer a gravity-dependent alveolar collapse, resulting in a reduction of tidal volume, residual alveolar excessive distension, and ventilator-related lung injury(VILI) induced by unreasonable ventilator setting.Prone ventilation (PPV) improves the gravity-dependent alveolar ventilation and promotes lung recruitment in the gravity-dependent area and improves lung compliance. Previous studies showed that prolonged PPV combined with low tidal volume(LTV) lung protected ventilation can significantly reduce the mortality of patients with moderate to severe ARDS.Although more than 60% of patients with moderate to severe ARDS due to COVID-19 has been widely implemented PPV,studies showed an improvement in oxygenation in patients with ARDS(the P/F radio improved by more than 20% before and after PPV) was 9-77%, that is, That is, some patients are unresponsive to PPV. In addition, some patients showed CO2 responsiveness after PPV(ventilation rate (VR) decreased significantly after PPV).The tools for monitoring the effects of PPV on ventilation and blood flow at bedside are still lacking, Electrical impedance tomography (EIT) is a non-invasive, non-radiative, real-time bedside lung imaging technique that can monitor local lung ventilation distribution. This study intends to use EIT to evaluate pulmonary ventilation, blood flow distribution and local V/Q ratio before and after PPV, as well as to monitor the changes in pulmonary physiology before and after PPV, explore the mechanism of PPV improving oxygenation by combined with the changes in oxygenation, and explore the factors that predict and affect PPV responsiveness.
Acute respiratory distress syndrome (ARDS) is when a person's lungs become inflamed, which can be caused by infection, trauma, surgery, blood transfusion, or burn. ARDS often leads to a situation where the person cannot breathe independently and needs machines' help. Once the lungs are inflamed, the small air sacs responsible for exchanging gases (i.e., ventilation) and the blood flow in the lungs (i.e., perfusion) can be affected. In the past, most research focused on studying ventilation physiology and how to help people breathe with machines. Less was done on perfusion because it requires imaging techniques such as computed tomography with intravenous contrast and radiation. One treatment option for low oxygen levels is inhaled nitric oxide (iNO), a gas that can dilate the lung blood vessels and improve oxygenation; however, it is not always clear whether this treatment will work. Electrical Impedance Tomography (EIT) is a bedside and accessible imaging technique that is radiation-free and non-invasive and can potentially detect changes in lung perfusion. EIT can perform multiple measurements; it is portable and accessible. This prospective interventional study aims to assess changes in regional blood perfusion in the lungs of patients with ARDS in response to iNO utilizing EIT. The main questions it aims to answer are: 1. If EIT can measure lung regional perfusion response to an iNO challenge of 20ppm for 15 minutes. 2. If EIT is comparable to dual-energy computed tomography (DECT), the gold-standard method to detect changes in regional lung perfusion. 3. If EIT can be an imaging marker to identify ARDS severity Participants will be divided into two cohorts: 1. Cohort 1 (n=60): Participants will be asked to be monitored by EIT before, during, and after the administration of iNO (20 ppm) for 15 minutes (OFF-ON-OFF) 2. Cohort 2 (N=10): Participants will be asked to be monitored by EIT and DECT before and during the administration of iNO (20 ppm) for 15 minutes (OFF-ON).
This study evaluates the effects of prone positioning on homogenization of ventilation.
The investigators present a randomised open label phase Ib/IIa trial of nebulised unfractionated heparin to evaluate the effect of nebulised unfractionated heparin on the procoagulant response in ICU patients with SARS-CoV-2 requiring advanced respiratory support. As this is one of the first studies of nebulised heparin in COVID 19 lung disease the investigators will assess safety as a co-primary outcome.