Renal

• Pre-Renal

  • Pathophysiology: These are factors that reduce blood flow to the kidneys, leading to decreased oxygen delivery. Common causes include dehydration, severe blood loss (hemorrhage), HR, and conditions that affect blood vessels supplying the kidneys. Diminished blood flow; hypoperfusion of kidney, volume depletion, vasodilation, decreased cardiac output. Can progress to intrarenal damage.
  • Prolonged low cardiac output
  • Prolonged hypotension
  • Prolonged volume depletion
  • Reno-vascular thrombosis
• Intra-renal

  • These are factors that directly damaged kidney tissue directly. Common intrinsic causes include infections, toxins, medications, and conditions like glomerulonephritis (inflammation of the kidney’s filtering units) or acute tubular necrosis (damage to the kidney tubules.) Glomerular, vascular, and/or hematological problem, acute tubular necrosis (ATN), ischemia nephrotoxic agents, antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs), contrast-induced, Rhabdomyolysis.
  • Kidney ischemia
  • Toxins
  • Infection
• Post-renal

  • These are factors that obstruct the flow of urine from the kidneys. Ex: include kidney stones, tumors, and an enlarged prostate. Obstruction of flow, increased intratubular pressure leads to decreased GFR, reverses when obstruction is removed.
  • Obstruction
• Diffusion: Movement of solutes from an area of greater concentration to an area of lesser concentration
• Osmosis: Movement of fluid from an area of lesser concentration of solutes to area of greater concentration

  • Glucose in dialysate creates osmotic gradient to pull fluid from the blood
• Ultrafiltration

  • Water and fluid removal
  • Results when there is an osmotic gradient or pressure gradient across membrane
  • PH – glucose in dialysis
  • HD – pressure gradient
  • Excess fluids moves into dialysate
• Hemodialysis

  • Intermittent Hemodialysis
  • Similar to natural diffusion
  • Circulates blood through semipermeable tubing through a dialysate
  • Three big pulls: urea, creatinine & potassium
  • Water (ultrafiltration) fluid volume control
  • Access: AV shunt, grafts, vascular
  • Very effective, done bedside in ICU over 3-4 hours
  • Weight patient daily
  • Monitor labs
  • DO not give water soluble meds before treatment, hold antihypertensives, do not give 6 hours before treatment
  • Assess access frequently
• Peritoneal dialysis

  • Peritoneal access is obtained by inserting a catheter through anterior abdominal wall
  • Three phases of PD cycle (manual):
  • Inflow (fill) – 2 to 3 L over 10 minutes
  • Dwell (equilibration) 20 to 30 minutes – 8 hours
  • Drain 15 to 10 minutes
  • Cycle is repeated
  • Called an exchange
  • Volume depends on size of peritoneal cavity
  • Dextrose – osmotic agent
  • Can be automated at night, done by patients in their homes as well as in the acute care setting.
• Continuous renal replacement therapy (CRRT)

  • Same principles of hemodialysis, but occurs at a gentler rate
  • Minimizes hypotension and electrolyte shifts
  • RNs who manage patients on CRRT need additional training
  • Initial set up done by dialysis RN, as directed by nephrologist
• Types of CRRT:

  • Slow continuous ultrafiltration (SCUF) – goal is fluid removal – no waste removal, no replacement fluid
  • Continuous venovenous hemofiltration (CVVH) – fluid and some waste product removal – some replacement fluid is used to increase flow
  • Continuous venovenous hemodialysis (CVVHD) – some fluid and max waste product removal
  • Continuous venovenous hemodiafiltration (CVVHDF) – max fluid and waste product removal
• Complications:

  Peritoneal dialysis:

  • Infection
  • Hernia, bleeding
  • Pulmonary complications

  Intermittent hemodialysis:

  • Infection of temporary access
  • Hypotension, F&E shifts
  • Bleeding

  CRRT:

  • Infection
  • Bleeding