renal 3
Glomerular Filtration Rate (GFR) and kidney function
GFR is the main measure of kidney filtration function; serves as a window into how quickly kidneys are filtering waste.
As GFR drops, the need for dialysis becomes more likely; in practice, discussions shift toward dialysis planning as function declines.
A common way patients describe kidney function clinically is by GFR; when someone says their kidney function is "15%" or "10%" or "20%", they are referring to the glomerular filtration rate (GFR).
A quick practical reference from the transcript: when GFR falls below about 15% dialysis is often indicated.
Albumin and protein in the urine indicate kidney damage: the transcript mentions a number around 300 related to albumin; elevated albumin in urine signals diseased kidneys (albuminuria).
Why albuminuria matters: albumin should not be present in urine; chronic kidney damage allows leakage of protein into urine, reflecting nephron injury.
Summary takeaway: higher GFR is good; falling GFR signals progression toward dialysis; albuminuria is a marker of kidney disease.
Causes and pathophysiology of chronic kidney disease (CKD)
The two biggest culprits: hypertension and diabetes.
Hypertension:
Causes thickening of arterial walls in renal vessels, reducing blood flow to the kidneys (ischemic injury).
This ischemia contributes to nephron damage and a cycle of worsening kidney function.
Diabetes:
Hyperglycemia and metabolic changes damage glomeruli and tubules over time.
Other causes (also mentioned):
Lupus (SLE), rheumatoid arthritis (RA), infections like HIV, chronic NSAID use, toxins such as tobacco.
Common clinical signs of CKD progression:
Oliguria (low urine output) is typical.
Azotemia: buildup of nitrogenous waste products (e.g., urea).
Nausea, loss of appetite, and encephalopathy from uremia.
Pericarditis risk increases with uremia; also uremic frost (rare) can appear as urea excreted through sweat.
Bone health: kidney failure affects vitamin D activation, leading to weakened bones.
Hypertension perpetuates kidney damage; a positive feedback loop can occur via renin release increasing BP and renal injury.
Anemia and fluid retention (edema) are common.
Urea-related symptoms and risks:
Urea buildup contributes to nausea, anorexia, encephalopathy, pericarditis risk, and bleeding tendencies due to clotting disturbances.
Important organ interactions:
Kidney failure can lead to cardiovascular consequences (e.g., heart failure) and electrolyte disturbances that feed back into kidney function.
Clinical signs and measurements in CKD
Urine output: typically decreased (oliguria) with CKD.
Azotemia: accumulation of nitrogenous wastes (e.g., urea) in the blood.
Uremia-associated symptoms: nausea, poor appetite, encephalopathy.
Pericarditis risk from uremia; manifestations include fever and chest pain in classic presentations (see later section on pericarditis).
Electrolyte and mineral disturbances: hyperkalemia later in CKD; hypocalcemia and bone-mineral disorders may occur.
Blood pressure and cardiac effects: hypertension and potential heart failure create a positive feedback loop that worsens renal perfusion.
Uremia, pericarditis, and related complications
Uremia can cause pericarditis due to irritation of the pericardium from buildup of waste products.
Typical pericarditis presentation (noted in the transcript as a teaching cue):
Chest pain that improves when leaning forward
Possible diffuse ST elevations and PR segment depression on ECG
Uremic bleeding risk: urea can affect clotting, increasing bleeding tendencies.
Uremic frost: a powdery appearance from sweat evaporation of urea in late-stage renal failure.
Vitamin D and calcium: kidney failure impairs activation of vitamin D, contributing to bone weakness and calcium balance issues.
Glomerular filtration rate (GFR) staging and planning for dialysis
Planning and initiation considerations:
Start planning for dialysis when GFR is around 20\,\text{mL/min/1.73 m}^2.
Most people begin dialysis when GFR falls below 12\,\text{mL/min/1.73 m}^2.
Contemporary guidelines increasingly consider symptoms (fatigue, nausea, decreased appetite, shortness of breath) rather than a single GFR number to decide when to start dialysis.
Symptoms that can trigger dialysis consideration:
Severe fatigue, nausea, decreased appetite, shortness of breath due to fluid overload or electrolyte disturbances.
Treatment options discuss early planning: conservative care, kidney transplant, or dialysis.
Transplant considerations:
Living donors (often family/friends) vs deceased donors; living donors tend to yield longer graft survival and earlier transplant timing.
In some regions, deceased-donor availability can take several years; transplantation is generally associated with longer survival than remaining on dialysis.
Conservative care: choosing to forgo dialysis and focus on diet/medication to preserve remaining kidney function; acknowledges progression toward end-stage renal disease and eventual death in some cases.
Dialysis: indications, planning, and options
Indications and planning:
Dialysis planning typically begins when GFR starts to decline significantly or when symptoms emerge.
Planning often spans months because dialysis setup (e.g., creating a fistula) requires time to mature.
Dialysis options overview:
Hemodialysis (HD): blood is filtered outside the body using an artificial kidney (dialyzer).
Peritoneal dialysis (PD): uses the peritoneal membrane as the filtration surface, with dialysate introduced into and drained from the abdomen.
Hemodialysis specifics:
Typical HD schedule: about 4\ hours\,\times\,3\ weeks (often 3 times per week, commonly in a clinic or hospital).
Vascular access types:
Arteriovenous (AV) fistula: preferred long-term access; requires time to mature (months).
AV graft: prosthetic connection; shorter maturation period but higher infection risk than fistula.
Central venous catheter (temporary access): used when fistula/graft not yet ready; higher infection risk; not ideal for long-term use.
Fistula maturation signs and care:
Thill: a palpable vibration over the fistula indicating patency.
Bruit: a whooshing sound heard with auscultation indicating blood flow.
Avoid IV lines or blood pressure measurements on the fistula arm to prevent injury and loss of access.
Home HD and nocturnal HD: some patients can perform HD at home, including overnight sessions.
Peritoneal dialysis (PD) specifics:
PD uses the peritoneum as the filtration surface; dialysate is instilled into the peritoneal cavity and dwells for several hours before drainage.
Exchanges (the process of filling and draining): generally take 20–30 minutes per exchange.
Two main PD modalities:
CAPD (continuous ambulatory PD): four exchanges daily performed by the patient during the day.
APD (automated PD): a machine performs exchanges overnight (7–10 hours) while the patient sleeps.
Choosing dialysis modality:
Hospital-based dialysis may be necessary for acute care or if the patient cannot self-manage at home.
Home dialysis requires reliable support, cognitive function, and ability to self-care; factors like addiction, cognitive impairment, or other medical conditions can affect suitability.
Transplant vs dialysis timing in practice:
Transplant is often preferred when feasible, but not all patients are candidates.
Living-donor transplants can occur earlier and often have better outcomes than deceased-donor transplants.
Vascular access and HD care: fistulas, grafts, and lines
AV fistula (preferred long-term access):
Created surgically by connecting an artery to a vein; over months, the vein becomes arterialized and suitable for cannulation.
Benefits: lower infection rates, longer patency, better outcomes than grafts/central lines.
Complications and maintenance:
Infection risk, stenosis, thrombotic occlusion, and steal syndrome (ischemia to the limb) can occur but are less common with proper care.
AV graft (prosthetic) access:
Requires less time to mature (weeks) but higher risk of infection and stenosis; cannulation can be more frequent due to graft properties.
Central venous catheter (temporary HD access):
Central line (e.g., subclavian or internal jugular) provides rapid access but carries high infection risk and thrombotic complications; not ideal for long-term use.
Fistula examination and troubleshooting:
Check for a palpable thrill and audible bruit to assess patency.
Do not place IV lines or perform blood pressure measurements on the fistula arm; avoid disturbing the cannulation sites.
If fistula fails or loses function, consider alternative access (another fistula, graft, or temporary catheter) after medical guidance.
Air embolism and line problems:
In the event of suspected air embolism, transport considerations include left lateral decubitus position with head elevated to minimize embolus travel.
Ensure line integrity and rapid recognition of line defects to prevent air embolism.
Handling bleeding in a fistula:
For fistula bleeding, apply direct pressure; tourniquet use is controversial because it can damage fistula or surrounding tissue; use cap/adhesive devices as temporary measures if available.
Dialysis-related complications and EMS considerations
Major risks after missed dialysis or during dialysis:
Hyperkalemia and fluid overload (leading to pulmonary edema) are among the most dangerous acute issues.
Hypotension from excessive fluid removal during HD.
Disequilibrium syndrome: rapid osmotic shifts when removing solutes too quickly, leading to neurologic symptoms (nausea, headache, dizziness).
Access-related issues: fistula or graft infection, thrombosis, or bleeding; catheter-related bloodstream infections.
Dysrhythmias due to electrolyte disturbances (notably hyperkalemia and hypokalemia).
Embolism risk (air embolism with line problems during dialysis).
EMS management themes for dialysis patients:
Assess breathing and lung status; watch for fluid overload and crackles on auscultation.
Use supportive therapies (e.g., CPAP for pulmonary edema if indicated, nitro for chest pain with careful consideration).
Be prepared to treat hyperkalemia emergently if suspected (calcium for stabilization, bicarbonate, insulin with dextrose, albuterol, etc.).
Avoid giving fluids to patients who cannot clear fluids well (dialysis patients often have limited fluid clearance).
If cardiac arrest occurs and there is no other option, prioritize securing IV access; consider intraosseous access if needed; fistula access should be preserved for dialysis if possible.
Special considerations after dialysis sessions:
Post-dialysis hypotension is possible due to rapid fluid removal; reassess hemodynamics and airway/breathing.
Disequilibrium syndrome can occur soon after dialysis in some patients; monitor for neurologic symptoms.
Peritoneal dialysis (PD) and infection risk:
Peritonitis is a high risk with PD; signs include abdominal pain, fever, cloudy dialysis effluent, and rebound tenderness.
In PD patients, high suspicion for infection is warranted if they have abdominal pain or systemic symptoms.
Urinary symptoms and infectious processes related to CKD
Urinary symptoms triad (classic for UTIs):
Painful urination (dysuria), frequent urge to urinate, and difficulty urinating.
Urinary tract infection progression:
UTIs can progress to pyelonephritis if unchecked, presenting with nausea, vomiting, fever, CVA tenderness, and systemic symptoms.
Pyelonephritis is a kidney infection and is more ill-appearing than a simple UTI.
CVA tenderness:
Costovertebral angle (CVA) tenderness assessed by tapping the area around where the kidneys sit; positive CVA tenderness indicates pyelonephritis or kidney inflammation.
Kidney stones (renal colic):
Severe flank or groin pain with possible radiation; may cause hematuria; some stones require intervention (shocking waves or surgical removal) if they obstruct the ureter.
Other renal infections and post-renal issues:
Post-renal AKI can result from obstruction (e.g., stones, strictures) blocking urine flow and causing kidney damage.
Peritoneal dialysis (PD) specifics and complications
PD uses the peritoneum as a filtration surface, with dialysate instilled into the peritoneal cavity and drained after a dwell time.
Relevance of peritoneal surface: the peritoneum is highly effective at absorbing and diffusing wastes, but it also makes patients susceptible to peritonitis when infection occurs.
PD exchange types:
CAPD: continuous ambulatory PD with four daily exchanges performed by the patient.
APD: automated PD with a machine performing exchanges during sleep (7–10 hours).
PD-related peritonitis warning signs and management:
High index of suspicion for infection in PD patients, which can cause severe discomfort and systemic illness if not treated promptly.
Kidney transplant vs dialysis and ethical considerations
Transplant advantages:
Generally associated with longer survival and better quality of life than dialysis for many patients.
Living-donor transplants can occur earlier and may beat the waiting time seen with deceased-donor transplants.
Waiting times:
In some regions (e.g., Canada), deceased-donor wait times can be lengthy (the transcript notes around 5–8 years on average for deceased-donor waiting).
Transplant candidacy varies; not everyone is a candidate.
Conservative care:
For some patients, especially with multiple comorbidities, conservative management without dialysis may be chosen to focus on symptom relief and quality of life.
Additional topics for exam readiness
Kidney stones and renal colic:
Renal colic (torticol/renovascular pain) may involve radiating pain and hematuria; some stones require lithotripsy or surgical removal.
UTI and elderly sepsis risk:
UTIs are a common cause of sepsis in the elderly; CVA tenderness and dysuria may be present.
Renal emergencies requiring immediate care:
Testicular or ovarian torsion: sudden, severe abdominal or pelvic pain; emergency intervention required to salvage the organ.
Peritoneal dialysis and infection risk:
Infections are a major risk with PD; clinicians should maintain a high index of suspicion for peritonitis in symptomatic patients.
Empathy and patient-centered care:
Patients on dialysis often feel unwell; EMS and healthcare providers should approach with empathy and avoid blaming patients for dietary choices or missed dialysis.
Quick reference: key numerical and procedural points (LaTeX format)
Normal GFR: 90-120, indicating optimal kidney function, while values below 60 may suggest chronic kidney disease.
Dialysis consideration thresholds:
Plan around a patient’s lifestyle. If the patient has difficulty with mobility or perhaps already a terminal condition, some patient decline dialysis even if recommended by physicians.
Start dialysis commonly when the estimated GFR falls below 15 mL/min, as this indicates a significant decline in kidney function and a greater risk for serious complications.
Albumin in urine threshold mentioned: 300 (units not specified in the transcript; elevated albumin indicates kidney damage)
Potassium (normal range): 3.5 \le K^+ \le 5.0\ \text{mEq/L}
HD schedule example: 4\ hours\times 3\ \text{times/week}
PD exchange times: CAPD ~4 exchanges/day; APD ~7-10 hours of overnight exchanges
Hyperkalemia ECG progression (conceptual): tall peaked T waves → flattened P waves → widened QRS → sine wave
Calcium for hyperkalemia stabilization (EMS treatment): 1\ \text{g IV calcium gluconate over 10 min}
Sodium bicarbonate use: to correct acidosis and help shift potassium intracellular; avoid mixing with calcium to prevent sludge formation
Insulin + Dextrose for hyperkalemia: move potassium into cells; typical use is dextrose with insulin infusion (dose varies by protocol)
Albuterol for hyperkalemia: nebulized dose often referred to as 10–20 mg in the transcript
Access patency signs for AV fistula: thrill + bruit
Left lateral decubitus position with head elevated for suspected air embolism during dialysis complications