Using the peritoneal cavity (peritoneal dialysis).
General Idea of Dialysis
Recreating the semipermeable membrane function.
Semipermeable membrane: Allows movement of water, waste products, and electrolytes to maintain balance.
Dialysis aims to move fluids and particles through a semipermeable membrane.
Primary goals:
Restore fluid and electrolyte balance.
Control acid-base balance.
Remove toxins from the body.
Basic Principles of Dialysis
Diffusion: Movement of particles from high to low concentration to achieve balance.
Osmosis: Movement of water from high to low concentration to remove excess water from the body.
Ultrafiltration (Hemodialysis): Uses high pressure to move blood quickly.
Similar to hydrostatic pressure for perfusion.
Blood is pumped through a narrow environment at high rates (e.g., 300-400 mL/min), creating significant pressure.
Hemodialysis Process
Requires a vascular access due to high blood flow rates.
Blood is pulled out of the body by a pump and sent to a dialyzer (filter).
Dialyzer: Acts as an artificial kidney with thousands of narrow tubes (lumens).
Forces blood cells to line up.
Tubes have holes (semipermeable membrane) that allow water and small particles to be pushed out.
Filtered blood is returned to the patient.
Requires a dialysis machine and a dialysate solution.
Dialysate: Concentrated fluid that grabs excess water and particles; it's discarded after use.
Blood and dialysate do not mix due to pressure maintaining separation across the semipermeable membrane.
Hemodialysis Schedule and Implications
Intermittent treatment: Typically three times a week (Monday/Wednesday/Friday or Tuesday/Thursday/Saturday) for about four hours per session (run).
Patients build up fluid and waste products between treatments since they are not excreting.
Patients with end-stage renal disease are always uremic.
Dry weight: Optimal weight for the patient without fluid overload.
Determines how much fluid needs to be removed during dialysis.
Example: If a patient's dry weight is 150 lbs and they weigh 156 lbs, 6 lbs of fluid need to be removed.
The machine is programmed to remove the specified amount of fluid over four hours.
Patient Status and Risks
Patients are at their lowest volume and waste product levels during dialysis.
Immediately after dialysis, they start to rebuild fluid and waste products.
The most dangerous time for fluid volume overload is right before the next treatment.
Important to know the dialysis schedule to assess risk; for example, a patient on a Monday/Wednesday/Friday schedule is safer on Thursday than a patient on a Tuesday/Thursday/Saturday schedule.
Fluid Overload Symptoms
Listening to lungs for signs of fluid overload.
Developing symptoms such as pulmonary edema.
Dialysis Schedule and Emergency Room Visits
Patients often experience fluid volume overload after the weekend due to the two-day gap between Friday and Monday treatments.
Skipping dialysis appointments can exacerbate this.
Historical and Political Context of Hemodialysis
Before hemodialysis (late 1970s/early 1980s), patients with renal failure died.
Dialysis and transplant initiatives emerged simultaneously.
The government began funding hemodialysis, anticipating patients would eventually receive transplants.
Dialysis is 100% covered by the government.
The guaranteed funding has led to conflicts of interest, with some dialysis centers potentially prioritizing profit over patient care.
There are some reports of dialysis centers discouraging patients from joining transplant lists.
The Sick Role
In acute care, patients may temporarily adopt a sick role.
Healthcare providers need to move patients toward independence to avoid complications.
Chronic illness, such as renal failure, can lead to patients remaining in the sick role.
Hemodialysis patients may become dependent due to the disruption of their lives and constant feeling of illness.
This dependency can be exploited by dialysis centers.
Ethics and Organ Donation
The lack of organ donors is a significant issue.
The US has fewer transplants compared to Europe due to cultural factors and myths surrounding organ donation.
There are 150,000 to 200,000 patients on the transplant list in the US who may die without a transplant; kidney transplants are the most successful.
Organ donation occurs after brain death, which is a legal process with strict criteria.
Brain death means there is no blood flow to the brain, and the brain dies.
Healthcare providers must differentiate between futility and potential for recovery.
Organ donation is not done on patients in a coma.
The worst scandals in organ donation involve list jumping.
Separation between organ procurement and transplant teams.
Families who donate organs of brain-dead individuals experience less grief.
Tissue Donation
Tissue donation can occur after death, with consent from the family.
Tissues such as corneas and bones are used extensively in surgeries; only one religion (Hasidic Jews) has hesitations.
Dialysis Machine and Blood Volume
The tubing and filter in the dialysis machine contain a significant amount of the patient's blood volume (up to a third).
This can create a hypovolemic state, leading to hypotension.
Blood pressure management is crucial during dialysis; rapid blood pressure drops may necessitate stopping dialysis.
Anticoagulation with heparin is necessary to prevent blood clotting during dialysis.
Patients on dialysis are at a higher risk of bleeding.
General Patient Care
Focus on managing the patient when they are not on dialysis; watch for complications in between treatments.
Know the dialysis days.
Hold antihypertensives before dialysis to prevent hypotension.
Assess the vascular access.
Leave dialysis catheters alone to prevent infection or damage.
Vascular Access
Vascular access must be large enough to accommodate required blood flow.
Temporary vascular access: Dual-lumen hemodialysis catheters (jugular or subclavian) with a high risk of infection.
Long-term vascular access: Tunnelled catheters (PermaCath, Tessio) with a separated access point to reduce infection risk.
Arteriovenous (AV) access: Surgically developed fistula or graft with the least risk of infection.
AV access involves diverting arterial blood into a vein to make it enlarge.
Arteriovenous Access Types
Fistula: Direct connection between an artery and a vein.
Graft: Uses a Dacron graft to connect the artery and vein.
AV accesses develop over time and can fail.
AV Access Complications
Thrombosis (clotting).
Stenosis (narrowing).
Aneurysm or pseudoaneurysm (weakening of the vessel wall).
Ischemia (steal syndrome: too much arterial blood diverted to the vein).
AV Access Care
Protect the AV access arm.
No blood pressures, venipunctures, or IVs in that arm.
Document the presence of the AV access (e.g., left forearm AV access).
Assess for turbulent blood flow: Feel for a thrill (vibration) and listen for a bruit (sound) with a stethoscope.
The arm should look like an arm with an AV access; swelling, redness, or tenderness indicates a problem (e.g., DVT, cellulitis).
Peritoneal Dialysis (PD)
Uses the peritoneal lining as the semipermeable membrane.
A catheter is placed into the abdomen; a solution is instilled.
Through osmosis and diffusion, fluid and electrolytes are pulled out.
PD is a continuous, 24/7 process.
Advantages of Peritoneal Dialysis
Avoids the ups and downs and restrictions of hemodialysis.
Provides continuous dialysis, similar to the function of the kidneys.
May be more suitable for hemodynamically unstable patients but should be considered for all patients.
Promotes patient control and independence.
Types of Peritoneal Dialysis
Continuous Ambulatory Peritoneal Dialysis (CAPD): Patients perform exchanges manually throughout the day.
Cyclers: Machines can perform exchanges during the night.
Peritoneal dialysis involves instilling a highly concentrated dialysate solution into the abdominal cavity to draw out excess fluid and waste products through osmosis and diffusion, which is then discarded. The blood remains within the capillaries of the abdominal cavity, separated from the dialysate by the peritoneal membrane.