renal failure and dialysis

renal failure

• failure of kidneys to cleanse blood of waste

• primary method to cleanse body of waste:

• -formation of urea in liver (waste)

• -kidneys filter this out of blood and excrete in urine

• -kidneys fail, urea remains in blood

• uremia: high level of urea in blood (urine in blood)

what is urea?

• excess amino acids filters by liver

• the nitrogen of this forms urea molecules in liver

• urea’s excess C, H, and O released as energy while rest leaves the liver thru blood and as excreted urine

renal failure- symptoms and cause

• cause: urea converts to ammonia leading to toxicity in body systems

• Symptoms: -uremic pruritus (pimples)

• -uremic fetor (tongue patch)

• uremic frost: waste normally excreted by kidneys, accumulates in blood and deposited on skin thru sweat forming crystals (rare and indicates severity)

• more symptoms than this

acute renal failure (three causes, characterized by)

• potentially reversible decrease in kidney function

• sudden drop in urine output

• three causes: (related to decreased blood flow to kidneys by)

• 1.prerenal cause

• 2.intrarenal causes

• 3.postrenal cause

prerenal causes

• insufficient blood flow to kidneys by dehydration, severe blood loss, heart failure or drop in BP (shock)

• this is mostly reversible

intrarenal causes

• direct damage to kidney from drugs/toxins (antibiotics/constrast dyes)

• inflammation (prolonged lack of blood flow from ischemia)

• mostly irreversible

post renal causes

• blockage prevent urine from leaving body (ex. kidney stones)

acutre renal failure treatment

• involves treating cause of failure (pre, intra, postrenal)

• prerenal- blood flow is restored quick, damage is often reversible

• intrarenal- injury can be permanent if damage is severe

• postrenal- relieve obstruction, damage can be permanent if obstruction persisted for long

chronic renal disease (causes)

• diabetes is leading cause (damages small blood vessels, damaging glomeruli)

• glomerulonephritis, pyelonephritis..

• Renal hypertension: high BP caused by kidney damage

• polycystic kidney disease: inherited disorder causes massive enlargement of kidneys and cysts on kidneys (an autosomal dominant disorder)

renal failure by GFR

• glomerular filtration rate (GFR) used to stage CKD

• measure glomerular filtration rate ( volume of blood that passes thru glomeruli each minute)

• best overall index of kidney function

• eGFR method used to calculate GFR by blood sample

• eGFR: uses creatinine level with age, sex, weight to calculate

dialysis (procedure, and types)

• medical procedure removing waste and excess fluid from blood

• two types: hemodialysis and peritoneal dialysis

• both require patient blood, semipermeable membrane, and washing solution (waste in blood passes thru membrane by diffusion to enter solution leading to clean the blood)

hemodialysis

• machine filters blood thru dialyzer, remove waste, done multiple times in healthcare facility

• blood is routed form brachial or radial artery sent thru hemodialyzer

• hemodialyzer: semipermeable material and solution

• clean blood return to body via venous access

issue with hemodialysis?

• vascular access is an issue

• achieved either AV shunt or AV fistula

• AV shunt: shorter term dialysis- connects artery to vein with graft

• issue: can lead to infection/clotting complications

• AV fistula: longer term dialysis but golden standard for hemodialysis access)

• surgically by connecting vein to artery

• lower infection rate, good blood flow access

• issue: minimum 6-8 weeks for fistula to mature (difficult wait time for many patients)

peritoneal dialysis

• instilling dialyzing solution into peritoneal cavity by using membrane that lines peritoneal cavity

• dialyzing solution is similar to blood plasma and allows to stay abdomen for awhile

• waste diffuses out of peritoneal capillaries into solution then drained

• complications: peritonitis (signs: cloudy dialysate/abdominal pain)

peritoneal dialysis three methods- mostly daily

1. continuous ambulatory peritoneal dialysis: machine free, drains by gravity into peritoneal cavity via permanent connected catheter to external bag (done several times a day + once a night)

2. continuous cycling peritoneal dialysis: cycling machine and proceeds while patient sleeps

3. intermittent peritoneal dialysis: several times a week, usually at clinic

hemodialysis vs peritoneal dialysis

• hemodialysis much faster efficiency, but more expensive and time consuming

• usually limited to only large metropolitan areas