Uremia, Dialysis Indications/Access & Central Vein Stenosis

1) Review manifestions of uremia:
Uremia is a syndrome that affects virtually all organ systems -
-Neuro - Asterixis, Encephalopathy, Seizures, Peripheral Neuropathy (Carpal Tunnel Syndrome, Foot Drop), Myoclonus.  Most commonly, subtle symptoms such as insomnia, restless leg syndrome, decreased memory and concentration, fatigue
-CV - Hypertension, Arrythmias, LVH, Increased predisposition to MI and SCD, Accelerated atherosclerosis and coronary calcification, Volume overload, Pericardial effusions and pericarditis
-Pulm - pulmonary edema due to volume overload
-GI - nausea/vomiting, anorexia, hiccups, weight loss, increased GI bleeding
-Renal - Hyperkalemia, Metabolic Acidosis (Non-gap early, Anion-Gap later), Hypocalcemia, Hypermagnesemia, Hyperphosphatemia
-Heme - Anemia, Increased bleeding due to uremic platelet dysfunction, Decreased WBC function leading to increased infections
-ID - increased susceptibility to infections
-Endocrine/Metabolic - secondary hyperparathyroidism, leading to bone disease, increased triglycerides, and others
-Skin - pruritis, rarely uremic frost

2) Indications for Dialysis in acute and chronic kidney disease:
Everyone know the AEIOU mneumonic (Refractory Acidosis, Electrolytes particularly hyperkalemia, Intoxications such as salicylates and lithium, Overload of volume, Uremia specifically encephalopathy, bleeding, and pericarditis).  However, we also mentioned some of the indications of starting HD in patients with progressive, severe chronic kidney disease:
- Refractory Hypertension despite multiple meds
- Persistent nausea/vomiting
- Signs of malnutrition and weight loss - low albumin is highly associated with increased mortality in this population.
- GFR <10-15

3) Review access modalities for dialysis
- AV Fistulas - generally the best option due to best long-term patency (up to 20 years in some cases), least infectious and thrombosis risk.  Main problem is that it takes several months to mature - must plan ahead.  Also, more likely than AV Grafts to experience primary failure (up to 60% of fistulas never mature at all).
- AV Grafts - less preferred due to higher rate of infection and thrombosis, and thus do not last nearly as long as fistulas.  However, advantage is that is able to be accessed much faster (usually a few weeks) and lower incidence of primary failure (<10-15%).
- Temporary dialysis lines - i.e. Trialysis lines, vs tunneled lines like permacaths - obviously, main advantage is instantaneous access, but limited by infectious risk, also high risk of causing central vein stenosis (see below).

4) Overview of central vein stenosis in dialysis patients and management:
Central vein stenosis usually results from prior central venous catheter insertion, with the highest risk being the subclavian vein.  Also, it is associated with pacemaker lead placement. For both scenarios, it is thought to result from endothelial injury.  It is best evaluated with a fistulagram.
Management -
a) Observation if asymptomatic (often due to developement of extensive venous collaterals).
b) Angioplasty +/- stent - stenting appears to increase long-term success
c) Surgical bypass graft - bypass the obstruction
d) Occlusion of the AV fistula - ligating the access site relieves the problem of high flow and venous hypertension.  This is usually a last resort.

(Chanu Rhee MD, 6/14/10)