Plasma donation (plasmapheresis) is a procedure where blood is drawn, the plasma is separated, and the remaining components are returned to the donor. This process provides life-saving therapies but places a temporary strain on the circulatory system. Hypertension, or high blood pressure, is a condition where the force of blood against the artery walls is consistently too high, indicating pre-existing cardiovascular stress. Uncontrolled high blood pressure is a common reason for temporary deferral because the donation process can introduce risks to the donor’s health.
The Physical Demands of Plasmapheresis
Plasmapheresis uses a specialized apheresis machine to separate blood components. Blood is continuously drawn, and centrifugation separates the liquid plasma from the red blood cells and platelets. The machine then returns the remaining blood components, mixed with a saline solution, back into the donor’s body.
This cyclical process causes a temporary, rapid shift in the body’s fluid volume. Removing plasma, which is primarily water, immediately reduces the overall volume of circulating blood. To manage this loss, the donation center administers a replacement fluid, often saline, along with the returned components.
The procedure requires an anticoagulant, typically citrate, mixed with the blood to prevent clotting. A small percentage of citrate returns to the donor, binding with calcium in the bloodstream. This temporary decrease in calcium can cause side effects like tingling or numbness.
The entire procedure typically takes 60 to 90 minutes. The donor’s circulatory system must continuously adapt to these fluid shifts and the anticoagulant. This physiological adaptation constitutes the primary physical demand placed upon the donor’s body.
Why High Blood Pressure Poses a Risk to the Donor
The restriction against donating with high blood pressure is a safety measure intended to protect the donor from adverse events. Chronic hypertension means the heart and blood vessels are already working harder than normal, often leading to underlying damage like arterial stiffness. Plasmapheresis causes a temporary reduction in blood volume, requiring the cardiovascular system to compensate rapidly to maintain pressure.
For someone with uncontrolled hypertension, this sudden fluid shift can overwhelm the body’s ability to regulate pressure, increasing the chance of an adverse reaction. Common adverse events include dizziness, lightheadedness, or fainting (vasovagal reaction or syncope). These reactions are triggered by a sudden drop in blood pressure, which is more likely when the circulatory system is already stressed.
Donating places acute stress on arteries that may already be compromised by years of high blood pressure. The added strain and rapid changes in fluid dynamics could potentially increase the risk of a serious vascular compromise, such as a stroke or heart attack. Uncontrolled high blood pressure signals that the cardiovascular system may not be resilient enough to handle the demands of the donation process safely.
Understanding Eligibility Criteria and Deferral
Deferring a potential donor with high blood pressure is based on strict regulatory guidelines designed to ensure safety. The U.S. Food and Drug Administration (FDA) sets specific limits that must be met immediately prior to donation. The systolic blood pressure (the top number) must be between 90 and 180 mm Hg, and the diastolic pressure (the bottom number) must be between 50 and 100 mm Hg.
If a donor’s blood pressure falls outside these parameters, they are temporarily deferred from donating that day. This deferral is not permanent; the donor must work to bring their blood pressure back into the acceptable range. Those with controlled hypertension who take medication as prescribed are often eligible to donate.
Taking prescribed medication and maintaining good hydration can help ensure the measurement is within acceptable limits. If blood pressure remains too high, the individual is deferred, and staff advise consulting a healthcare provider to adjust medication or lifestyle factors. The screening process aims to differentiate between controlled, stable hypertension and uncontrolled, elevated blood pressure, protecting the individual while allowing safe donation.