Some Concepts On Plasma Exchange Therapy

By Kathleen Brooks


Recent advances in medical practice have been a great savior for patients suffering from a number of blood diseases. Plasma exchange therapy definitely falls among this list of major breakthroughs in providing effective patient care. It works by first harvesting the blood of the patient via externally visible veins and transferring it to a special device through a catheter. The special device separates cells from plasma (fluid part of blood) which is then replaced by new plasma and the mixture is taken up by the human through the veins.

Plasmapheresis is usually an outpatient form of treatment with no anesthesia required except in selected cases where local numbing may have to be done. Sometimes, the veins required for access may be too small to be seen. In such cases, larger, central veins in the neck and shoulder may have to be used. The patient is encouraged to drink lots of water before the procedure because of the associated dizziness and weakness.

Conditions in which toxic proteins exist in the plasma benefit most from this therapy. The relapsing form of multiple sclerosis is an example. However, treatment with plasmapheresis is only used when other forms of therapy have failed. It also helps control an acute attack. Other conditions that benefit include myasthenia gravis, thrombocytopenic purpura, atypical hemolytic uremic syndrome among others.

Any medical procedure comes with a risk however small. For plasmapheresis, an allergic reaction by the body to the new product may occur especially for patients who report a history of the same. Premedication to prevent the allergy should be administered in preparation for the actual exchange. Observing sterility should be paramount to avoid the challenge of having to get rid of a hospital acquired infection.

Another typical complication is the formation of clots once the blood leaves the body. This does not routinely occur because of the strict measures put in place. Sodium citrate, given as an infusion, binds calcium, the element needed for clots to form. Unfortunately, this puts the patient at risk of hypocalcemia (low levels of calcium in blood).

Functionality of key systems in the body may be put at risk if hypocalcemia is not reversed in a timely manner. It can present with numbness, tingling and convulsions. Worse cases may present with respiratory distress (due to spasms in the respiratory tract) and difficulty in swallowing (due to uncontrolled muscle contractions). Management is by infusion of fluids containing calcium.

A full cycle of plasmapheresis takes at least a fortnight. A single session usually lasts two to four hours. Weekly, about two or three sessions are done. Improvement is expected after a full course is completed. After a few weeks or months of symptom free living, the cycle may have to be repeated if the patient has a relapse.

This clearly shows that plasma exchange may not be permanently therapeutic for the illnesses in question. Moreover, it is very expensive to the affected person in the long run. It should be regarded as supportive form of treatment while focusing on better first line treatment options.




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