Critical Care & Adv Nephrology Final - Lecture 5 Hemodialysis and Peritoneal Dialysis

Dr. Smithburger: Slide Sledge Hammer Approach

Who is considered the "Father of Dialysis"?

Willem Kolff, MD

When was the first dialyzer constructed?

1943

Which of the following materials did Dr. Kolff improvise with to build his first dialyzer during WWII?

Sausage skins, orange juice cans, and a washing machine

Kolff's first dialyzer solved which clinical problem?

Acute kidney injury (but not chronic ESRD)

What was the main barrier preventing Kolff's first dialyzer from being used long-term in chronic ESRD?

Difficulty finding a vessel to repeatedly access the patient's blood

Who is considered the first "modern day" nephrologist and creator of the first semi-permanent dialysis access?

Belding Scribner

What was the Scribner Shunt?

Teflon-coated plastic tubes connecting an artery and vein, allowing repeated dialysis access without new incisions

When was the first outpatient dialysis center opened?

1962

Decisions about who would receive dialysis at the first outpatient dialysis center were made by an anonymous committee that based eligibility on:

"Social worth" — anticipated contribution to society

This anonymous dialysis allocation committee is historically known as:

The first bioethics committee

When did Congress codify lifelong subsidization of dialysis for eligible patients with ESRD?

1972

At what CKD stage should preparation for dialysis begin?

Stage 4 CKD (GFR < 30)

An arteriovenous fistula should ideally be surgically created:

1 year prior to anticipated HD need, or when GFR < 25 or SCr > 4 mg/dL

Renal replacement therapy is generally initiated when GFR falls below:

15 mL/min/1.73 m²

Which AV fistula creation criterion is correct?

Created when GFR < 25 mL/min/1.73 m² or SCr > 4 mg/dL

The "A" in the AEIOU mnemonic for indications to start dialysis stands for:

Acidosis

The "E" in AEIOU stands for:

Electrolyte abnormalities

The "I" in AEIOU stands for:

Intoxication

The "O" in AEIOU stands for:

Output (urine output issues)

The "U" in AEIOU stands for:

Uremic symptoms

The general philosophy regarding the timing of dialysis initiation is:

A compromise — extend dialysis-free period as long as possible, but don't wait so long that complications worsen post-dialysis quality of life

Which of the following is NOT a type of hemodialysis listed in the lecture?

Continuous ambulatory peritoneal dialysis (CAPD)

The two main types of peritoneal dialysis are:

CAPD and CCPD

What is the primary goal of hemodialysis?

Restore intracellular and extracellular fluid environment characteristic of normal kidney function

Hemodialysis is based on the diffusion of solutes:

Across a semipermeable membrane down a concentration gradient

Which solute typically moves from the BLOOD into the dialysate?

Urea

Which solute typically moves from the DIALYSATE into the blood?

Bicarbonate

What are the primary determinants of solute movement during dialysis (diffusion)?

Solute concentration and molecular weight

Which of the following diffuses MOST quickly across a dialyzer?

Urea (small molecule)

What is ultrafiltration?

Movement of water across the dialyzer membrane via hydrostatic or osmotic pressure

What is the primary purpose of ultrafiltration during hemodialysis?

To remove excess total body water

What is convection in hemodialysis?

Solutes are "dragged" across the membrane along with water transport

Convection in HD can be maximized by:

Increasing the pressure gradient across the membrane

Diffusion and convection (fluid removal) during HD:

Can be controlled separately, allowing personalized dialysis prescription

The four components of the hemodialysis apparatus are:

Dialyzer, dialysate, tubing, and machine to power/monitor

What is the most common type of dialyzer in current use?

Hollow-fiber (capillary) dialyzer

In a hollow-fiber dialyzer:

Blood circulates through hollow fibers; dialysate flows on the outside of the fiber bundle

Approximate dimensions of a typical hollow-fiber dialyzer:

12 inches long, 3 inches in diameter

What is the dialysate?

A solution of pure water, electrolytes, and salts

The dialysate is:

NOT a sterile solution and can be a source of infection if the dialyzer ruptures

Bicarbonate is included in the dialysate to:

Buffer to a physiologic pH

Typical sodium concentration in dialysate is:

134–140 mEq/L

Typical potassium concentration in dialysate is:

0–4 mEq/L

Typical bicarbonate concentration in dialysate is:

25–40 mEq/L

The "arterial" line in hemodialysis:

Carries blood from the patient to the dialyzer

The "venous" line in hemodialysis:

Carries dialyzed blood back to the patient

Typical blood flow rate during hemodialysis:

250–450 mL/min (with the blood pump)

During hemodialysis, what is administered to prevent clotting in the dialyzer?

Heparin (an anticoagulant)

During the dialysis procedure, blood is pumped into the dialyzer at approximately:

300–600 mL/min

Dialysate flow rate during hemodialysis is typically:

500–1000 mL/min

During HD, dialysate flows in which direction relative to blood flow?

Countercurrent to blood flow (opposite direction)

The rate of fluid removal from the patient during HD is controlled by:

Adjusting the pressure in the dialysate compartment

Standard in-center hemodialysis frequency and duration:

3 weekly sessions, 3–5 hours each

What is the goal "dry weight" for a hemodialysis patient?

Post-dialysis weight where the patient is normotensive AND edema-free

Kt/V_urea is best described as:

The fraction of the patient's total body water cleared of urea during a dialysis session

In Kt/V_urea, what does each variable represent?

K = urea clearance of the dialyzer, t = duration of session, V = patient's volume of urea distribution

What does Kt/V_urea = 1 mean?

The total volume of blood cleared of urea during a session is equal to the total body water of the patient

What is the minimum recommended Kt/V "dose" for hemodialysis?

1.2

Lower-than-recommended Kt/V doses are associated with:

Increased morbidity and mortality

Which of the following is the PREFERRED long-term hemodialysis access?

Arteriovenous fistula

An arteriovenous fistula is created by:

Joining an artery and vein in the arm; the vein grows wider/thicker over time

How long does an AV fistula typically take to mature before it can be used?

1–2 months

The AV fistula is preferred for long-term hemodialysis because of:

Less infection and clotting compared to grafts and catheters

A hemodialysis GRAFT is best described as:

A man-made tube used to connect an artery to a vein

How long does a graft typically take before it can be used for HD?

2–3 weeks

Compared to AV fistulas, AV grafts have:

Shorter survival and higher rates of infection and thrombosis

A central venous catheter is most appropriately used for hemodialysis when:

Disease progresses quickly and there is no time for vascular access (fistula/graft) to be placed

A central venous catheter for HD has:

Short lifespan and is prone to infection and thrombosis

What is the approximate incidence of HYPOTENSION during hemodialysis?

20–30%

Which of the following can contribute to intradialytic hypotension?

All of the above

Approximate incidence of HYPERTENSION during hemodialysis:

5–15%

Causes of intradialytic hypertension include all EXCEPT:

Excessive ultrafiltration causing hypovolemia

Approximate incidence of muscle cramps during hemodialysis:

5–20%

Common causes of cramps during hemodialysis include:

Muscle hypoperfusion (ultrafiltration/hypovolemia), hypotension, electrolyte imbalance, acid-base imbalance

What is the approximate incidence of pruritus in HD patients?

50–90%

Which of the following contributes to pruritus in HD patients?

All of the above

Fever and chills in an HD patient are usually due to:

Endotoxin release or infection of the dialysis catheter

What is the leading cause of mortality in HD patients (related to access)?

Vascular access infection (sepsis-related death is 100x greater in dialysis patients)

Non-pharmacologic management of intradialytic hypotension includes all EXCEPT:

Increasing dialysate temperature

Which IV fluid can be administered for intradialytic hypotension?

Normal or hypertonic saline

The BEST pharmacologic option for chronic intradialytic hypotension is:

Midodrine

What is the typical oral midodrine dose for HD-related hypotension?

5 mg given 2–3 times daily

Midodrine for HD-related hypotension can be administered:

On non-dialysis days OR just on HD days prior to HD

Recommended pharmacologic management of intradialytic hypertension includes:

Carvedilol 6.25 mg BID titrated to 50 mg BID as tolerated

When using carvedilol for intradialytic hypertension, what should be monitored during HD sessions?

Bradycardia and hypotension

Non-pharmacologic management of muscle cramps during HD includes:

C. Both A and B

When should a dialysis catheter be REMOVED in the setting of infection?

When the source is S. aureus, Pseudomonas species, or Candida species

Acute treatment of pruritus in HD patients includes:

Diphenhydramine or hydroxyzine

Prevention of pruritus in HD patients includes:

Topical emollients and adequate hemodialysis

Management of access thrombosis includes:

Flushing the line and administering alteplase 2 mg/2 mL per catheter port; replace catheter if needed

General infection-prevention measures for HD patients include:

Good hand hygiene and flu vaccination

Home hemodialysis is typically performed:

5–7x weekly for 2 hours per session (short daily sessions)

A potential benefit of home hemodialysis vs. in-center HD is:

Less fluid is usually removed at each session, reducing symptoms (headache, cramping, nausea, exhaustion)

Which of the following is NOT typically required to be a good candidate for home hemodialysis?

Living within 5 miles of a dialysis center

CRRT is renal replacement therapy that is intended to be applied:

24 hours/day in an ICU setting

Compared to traditional intermittent HD, CRRT has:

Slower solute clearance and less fluid shifts ("more physiologic")

A major advantage of CRRT in critically ill patients is that it:

Minimizes hypotension in hemodynamically unstable patients

CRRT is most commonly used in which patient population?

Acute renal failure (AKI) — but can be used in CKD patients who are hemodynamically unstable

A clinically important pearl about CRRT and infections is:

Patients may LACK fever even when infected

A common medication-dosing error in CRRT patients is:

Dosing medications based on serum creatinine without realizing the patient is on CRRT