Question

A client recently started on hemodialysis wants to know how the dialysis will take the place of his kidneys. The nurse's response is based on the knowledge that hemodialysis works by: A. Passing water through the dialyzing membrane B. Eliminating plasma proteins from the blood C. Lowering the pH by removing nonvolatile acids D. Filtering waste through a dialyzing membrane

Short answer

Answer: Hemodialysis works as a replacement for kidney function by filtering waste through a dialyzing membrane, which helps remove waste products, excess fluid, and maintain electrolyte balance in the blood, effectively mimicking the natural function of the kidneys.

Step-by-step solution

Option A: Passing water through the dialyzing membrane

During hemodialysis, water is passed through the dialyzing membrane, however, the main purpose of hemodialysis is not to pass the water but to filter wastes and excess fluid from the blood. So this option is partly correct but not the whole explanation.

Option B: Eliminating plasma proteins from the blood

Hemodialysis does not eliminate plasma proteins from the blood as they are important for maintaining fluid balance and immune function. Elimination of plasma proteins is not the primary purpose of hemodialysis, so this option is incorrect.

Option C: Lowering the pH by removing nonvolatile acids

Hemodialysis helps to maintain the pH balance of the blood by removing nonvolatile acids. Although this option is correct, it does not provide a complete explanation of how hemodialysis works to replace kidney function.

Option D: Filtering waste through a dialyzing membrane

Hemodialysis uses a dialyzing membrane to filter waste products, excess fluid, and maintain electrolyte balance in the blood. This process closely mimics the natural function of the kidneys. Therefore, this option is the most accurate and comprehensive answer. So, the correct answer is: D. Filtering waste through a dialyzing membrane

Key concepts

Dialyzing Membrane

The dialyzing membrane plays a crucial role in hemodialysis, acting as a cornerstone of this life-sustaining procedure. Imagine it as a semi-permeable barrier, designed specifically to replicate the selective filtration that healthy kidneys perform. During hemodialysis, a patient's blood is passed alongside or through this membrane. It allows waste products, excess chemicals, and fluid to pass through while retaining the vital components like red blood cells and plasma proteins.

Its function relies on principles of diffusion and osmosis. Small molecules like urea, creatinine, and excess ions such as potassium and sodium can move across the membrane, effectively removing them from the bloodstream. However, larger molecules, like the aforementioned proteins, are too large to pass through the pores of the membrane and remain in the blood. The design of this membrane is critical: it must allow enough of the small waste molecules to pass through quickly while preserving the necessary elements in the blood.

The Importance of Pore Size

One element of improvement for the dialyzing membrane is optimizing its pore size. This ensures efficient filtration without losing essential nutrients and proteins. Research and technological advancements continue to enhance its composition and structure, making hemodialysis an even safer and more effective treatment option for those with kidney failure.

Kidney Replacement Therapy

Kidney replacement therapy (KRT), also known as renal replacement therapy, encompasses several treatments, with hemodialysis being one of the primary methods. Kidney replacement therapy is essential when someone's kidneys can no longer perform the functions necessary to maintain the body's balance. The primary job of KRT, and thus hemodialysis, is to mimic the natural actions of the kidneys. This includes waste removal, fluid balance, and electrolyte regulation.

Kidneys filter blood, manage the balance of water and minerals, and remove waste through urine. Hemodialysis takes over these functions through an external circuit. A patient's blood is circulated through a machine equipped with the dialyzing membrane we previously discussed, which performs the filtering.

Advancements in Kidney Replacement Therapy

The field of KRT is continuously evolving, with improvements in techniques and equipment, such as the use of high-efficiency membranes and personalized treatment plans based on the patient's specific needs. By ensuring personalized care, kidney replacement therapies can maximize benefits and minimize potential risks and complications.

Blood pH Balance

The balance of blood pH is a finely tuned process in the human body, crucial for maintaining a state of health. The kidneys play an essential role in this, by regulating the amount of bicarbonate and hydrogen ions in the blood. Hemodialysis aids in this regulatory function when the kidneys cannot perform effectively.

Hemodialysis filters out nonvolatile acids, such as sulfuric and phosphoric acids, which are normally expelled in the urine. The removal of these acids during hemodialysis helps to avoid the accumulation that leads to a decrease in blood pH, a condition known as acidosis. Moreover, the dialysis solution can be tailored to restore the proper balance by adding bicarbonate, which acts as a buffer to neutralize excess acids, thus maintaining the blood's pH within its narrow, optimal range.

Personalized Dialysis for pH Balance

Advancements in the personalization of hemodialysis treatments allow the healthcare team to adjust the composition of the dialysis solution to meet the acid-base balance needs of each individual patient, thereby improving their overall well-being and preventing complications associated with acid-base imbalances.