COMPLICATIONS DURING HEMODIALYSIS
Even though the safety of the hemodialytic procedure has improved greatly over the years, the procedure is not without risks. Common problems are listed below.
A decrease in blood pressure is the most frequent complication reported during hemodialysis. When fluid is removed during hemodialysis, the osmotic pressure is increased and this prompts refilling from the interstitial space. The interstitial space is then refilled by fluid from the intracellular space. Excessive ultrafiltration with inadequate vascular refilling plays a major role in dialysis induced hypotension. The immediate treatment to hypotension is to discontinue dialysis and place the patient in a trendelenburg position. This will increase cardiac filling and may increase the blood pressure promptly.
In the majority of hemodialysis patients, cramps occur toward the end of the dialysis procedure after a significant volume of fluid has been removed by ultrafiltration. The immediate treatment for cramps is directed at restoring intravascular volume through the use of small boluses of isotonic saline. Prevention of cramps has been attempted with the prophylactic use of quinine sulfate at least 2 hours prior to dialysis.
Febrile episodes should be aggressively evaluated with appropriate wound and blood cultures. The suspicion of infection should be high. Treatment of endotoxin related fever is generally supportive with antipyretics. Temperatures should be recorded at the initiation and termination of dialysis treatment.
Patients on maintenance hemodialysis are at risk of cardiac arrhythmias. They occur predominately in association with hemodialysis or may occur in the interdialytic period. Both acute and chronic alterations in fluid, electrolyte, and acid-base homeostasis may be arrhythmogenic in these patients.
Hemolysis may result from a number of biochemical and toxic insults during the dialysis procedure. The half-life of red blood cells in renal failure patients is approximately one half to one third of normal and the cells are particularly susceptible to membrane injury.
A fall in arterial PO2 is a frequent complication of hemodialysis that occurs in nearly 90% of patients. The drop ranges from 5 to 35 mm Hg, and reaches its peak between 30 - 60 minutes after beginning dialysis. This is obviously undesirable for patients with underlying cardiopulmonary disease. Also, patients on mechanical ventilators with constant minute volume and inspired oxygen concentration can still develop hypoxemia during hemodialysis.