vasoocclusive

Vasoocclusive is an adjective used in medicine to describe events or conditions that cause occlusion of a blood vessel, resulting in reduced or interrupted blood flow. Occlusion can arise from thrombus or embolus, vessel constriction, swelling, or the adhesion and aggregation of cells and inflammatory mediators that block microvasculature.

Most commonly encountered in reference to vaso-occlusive crisis (VOC), a frequent and painful complication of sickle cell disease. In VOC, rigid, sickled red blood cells, along with white cells and platelets, adhere to endothelium and obstruct small vessels, leading to tissue ischemia and severe pain. VOC can affect bones, joints, chest, abdomen, and other organs.

Pathophysiology is multifactorial, involving increased blood viscosity, red blood cell deformability, cellular adhesion, endothelial activation, coagulation changes, and nitric oxide dysregulation. Local hypoxia, acidosis, and inflammation perpetuate vascular blockage.

Triggers include dehydration, infection, fever, cold exposure, and stress. Diagnosis is typically clinical, based on history and physical examination during episodes; imaging and laboratory studies may be used to assess organ involvement and to rule out alternative causes of pain.

Management emphasizes prompt pain relief with analgesia, adequate hydration, and supplemental oxygen as needed. Treat triggers and complications; disease-modifying therapies for sickle cell disease reduce VOC frequency or severity (e.g., hydroxyurea, crizanlizumab, voxelotor, L-glutamine). Severe VOC may require hospitalization and transfusion.

Prevention focuses on maintaining hydration, avoiding triggers, vaccination against infections, and adherence to disease-modifying therapies to lower the risk of VOC and organ damage. Vasoocclusive events are a general mechanism underlying ischemia in various conditions, including but not limited to sickle cell disease.