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Sponsor: Massachusetts General Hospital
Conditions: Acute Respiratory Distress Syndrome, Ventilation Perfusion Mismatch
Interventions: Nitric Oxide
Countries: United States
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. Prone position has been used for several years in the care of ARDS patients and has been demonstrated to improve survival in more severe patients. It is not known how iNO and prone positioning interact in determining the distribution of pulmonary perfusion and whether their combine use can benefit ARDS patients. 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 and to prone positioning 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 can measure the lung regional perfusion responses to prone position, applied alone and in combination with iNO. 3. If EIT is comparable to dual-energy computed tomography (DECT), the gold-standard method, in the detection of changes in regional lung perfusion due to iNO. 4. If EIT can be an imaging marker to identify ARDS severity Participants will be divided into three cohorts: 1. Sub-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) in the supine position 2. Sub-Cohort 2 (N=10): Participants will be asked to be monitored by EIT before and during the administration of iNO (20 ppm) for 15 minutes (OFF-ON) in both the supine and in the prone position. The same subjects will be monitored also with DECT in the supine position and then after 30 minutes in the prone position (without NO administration). 3. Sub-Cohort 3 (N=10): In this subset of Sub-Cohort 1, subjects will be asked to be monitored also with DECT (in addition to EIT) in the supine body position before iNO and after 15 minutes while receiving iNO.
Sex: ALL
Age: 18 Years to 80 Years
Healthy volunteers: No
Study type: INTERVENTIONAL
Inclusion Criteria: * Adult intubated and mechanically ventilated patients (≥ 18 years old) admitted to the intensive care unit (ICU) * ARDS diagnosis with mild to moderate severity by Berlin criteria1 (100 mmHg \< PaO2/FiO2 \<= 300 mmHg) * Presence of an arterial line for blood gas measurement and blood pressure monitoring and of a central line for hypertonic saline injection Exclusion Criteria: * Suspected pregnancy, pregnancy or less than six weeks postpartum * Younger than 18 years or older than 80 years * Baseline methemoglobin ≥ 5% * Subjects enrolled in another interventional research study * Presence of pneumothorax * Usage of any devices with electric current generation, such as a pacemaker or internal cardiac defibrillator * Preexisting chronic lung disease or pulmonary hypertension * Past medical history of lung malignancy or pneumonectomy, or lung transplant * Left ventricle ejection fraction \<20% * Hemodynamic instability is defined as: * Persistent systolic blood pressure \<90 mmHg and/or \>180 mmHg despite the use of vasopressor or vasodilators, or * Requiring an increment in inotropic vasopressors over the past two hours just before enrollment: more than 15 mcg/min for norepinephrine and dopamine, more than 10 mcg/min in epinephrine, and more than 50 mcg/ min for phenylephrine. * Hypernatremia (serum sodium \> 150 mEq/L) * Patients cannot be enrolled for DECT if they have: * History of allergic reaction to intravenous contrast * Renal dysfunction on the day of the study (serum creatinine \> 1.5 mg/dL)
- Boston, Massachusetts, United States