Acute kidney failure resident survival guide
Acute Renal Failure is an abrupt reduction in kidney function defined as at-least one of the following: 1. an absolute increase in the serum levels of creatinine of 26.4 μmol/L(0.3mg/dl) or more; 2. a percentage increase in the serum levels of creatinine of more than 50%(1.5 fold increase from baseline); or 3. a reduction in volume of urine output(oliguria <0.5 ml/kg hourly for >6 hours. Acute renal failure is increasingly common, particularly in elderly population, hospital inpatients, and critically ill patients and it carries a high mortality. The most common cause of in-hospital acute renal failure in acute tubular necrosis resulting from multiple nephrotoxic insults such as sepsis, hypotension, and use of nephrotoxic drugs or radio-contrast media. Patients at risk include elderly people, diabetics, patients with hypertension or vascular disease, and those pre-existing renal impairment. To aid the diagnosis and management, it is important to find out the underlying cause, whether its pre-renal, renal or post renal. Initial workup should be carried out as soon as the patient is encountered and any life threatening situation should be treated promptly.
Life Threatening Causes
Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.
- Renal Hypoperfusion due to Abdominal aortic aneurysm
- Acute tubular necrosis
- Sepsis leading to hypotension
|Acute renal failure|
|Pre-renal causes||Intrinsic renal causes||Post-renal causes|
|Glomerular disease||Tubular injury||Interestitial nephritis||Vascular diseases|
|Inflammation (glomerulonephritis)||Toxins||Oclusion (thrombosis or embolism|
Pre Renal Causes
- Renal Hypoperfusion
- Oedematous States
Intrinsic Renal Causes
- Glomerular disease
- Inflammatory- post-infectious glomerulonephritis, cryoglobulinaemia, Henoch-Schonlein purpura, systemic lupus erythematosus, antineutrophil cytoplasmic antibody associated glomerulonephritis, anti-glomerular basement membrane disease
- Thrombotic- disseminated intravascular coagulation, thrombotic microangiopathy
- Interstitial Nephritis
- Tubular Injury
Post Renal Causes
Shown below is an algorithm summarizing an step by step approach to diagnosis the cause of Acute Renal Failure to aid in the management.
Patient presenting features
❑ Oliguria (sudden or gradual)
Medical History and Risk Factors
❑ inquire about previous similar episodes
❑ Inquire about drug history
❑ inquire about recent hospitalization-rule out Acute Tubular Necrosis
❑ history of kidney stones<br ❑ Associated symptoms
❑ Basic Blood
❑ Urine analysis
Draw a conclusion
❑ Treat any life threatening features first—shock, respiratory failure, hyperkalaemia
|Renal failure diagnostic approach|
Is this acute or chronic renal failure
Has obstruction been excluded?
Is the patient euvolemic?
Has a major vascular occlusion occurred?
Definitive Management depends upon the underlying cause; however, the initial approach is directed to treat any life-threatening feature attempting to halt or reverse the decline of the renal function, and if unsuccessful providing support by renal replacement anticipating a renal recovery. Hyperkalemia, pulmonary edema, and severe acidosis require immediate attention.
Severe hyperkalemia is a medical emergency and should be immediately treated with infusion of calcium. Treatment with calcium is a temporizing measure “buying time” while measures are started to reduce the serum potassium through increasing cellular uptake. Overall these measures will bring the potassium back to normal; however, still the body will be in excess. If pure pre-renal failure, measures can be taken to excrete the potassium through the kidney by giving resins. Ultimately, if hyperkalemia is refractory to all the above measures, hemodialysis ca be started.
|Serum potassium>6.5 is a medical emergency|
|Immediate action||Reduction in plasma potassium concentration||Removal of potassium from the body|
|Calcium gluconate or carbonate||If pure pre-renal failure, renal excretion will serve to return the whole body levels to normal|
|to stabilize the myocardium and prevent cardiac arrythmias||Ion exhange resins calcium polystrene or sodium polystrene||Hemodialysis for refractory hyperkalemia|
|Insulin with glucpse||beta-2 agonist||Sodium bicarbonate|
2.TREATING PULMONARY EDEMA
Pulmonary oedema is often the result of excessive fluid resuscitation, and can be anticipated in many patients—especially those with known cardiac dysfunction, the elderly, and those who appear volume replete at the outset—and hopefully avoided by more judicious intravenous fluid therapy. If respiratory failure, intubate the patient and start mechanical ventilation.While these measures are being undertaken, pharmacological treatment to offload the decompensated heart can be started. If these measures fail, hemodialysis or hemofiltration can be used.
|Respiratory failure||Pharmacological treatment|
|I/V opioids(diamorphine)||I/V infusion of glyceryl nitrate||provoke diuresis with large doses of diuretics such as furesemide|
|Supplemental oxygen OR intubate and mechanically ventilate|
Severe metabolic acidosis (blood pH <7.2) often accompanies ARF and arises through a variety of mechanisms, related both to reduced renal function and the underlying cause of the patient's illness. Systemic acidosis impairs cardiac contractility, induces bradycardia, produces vasodilatation, and augments hyperkalemia, among other effects. Reversing acidosis through the administration of an alkaline solution—sodium bicarbonate—would seem to be sensible, but there is very little evidence to show that it provides benefit. Isotonic (1.26%) solutions may have a role as fluid replacement therapy in stable patients with a moderate to severe acidosis and a requirement for fluid replacement, in whom dialysis is not imminent. Haemodialysis or haemofiltration will usually be required to treat severe acidosis in oligoanuric patients.
4.OTHER GENERAL MEASURES
❑ Fluid Balance-normal saline preferred but avoid fluid overload
❑ Relief of Obstruction-Bladder outflow obstruction if suspected should be relieved by passage of urethral catheter
❑ Uremic Platelet Dysfunction-Renal replacement therapy may improve but DDAVP and cryoprecipitate may be required
❑ Carbohydrate and protein requirement should be tailored individually and ideally delivered by enteral route
❑ Practice good infectious control
❑ Care of pressure areas
❑ DVT prophylaxis if prolonged immobility
- Normal Saline is the preferred fluid for resuscitation.
- Treat acute renal failure keeping in mind the cause behind it.
- Start Dialysis when needed.
- Correction of coagulopathy if needed with DDAVP and cryoprecipitate.
- DVT prophylaxis if needed.
- Avoid pressure ulcers.
- Avoid fluid overload.
- Dont use dopamine to increase renal perfusion.
- cautious use of diuretics if oliguria persists.
- Don't use nephrotoxic drugs (NSAIDs, ACE-I, Aminoglycosides)
- Avoid use of contrast media.