Acute kidney failure resident survival guide
Synonyms and keywords: Acute renal failure approach, An approach to acute renal failure, Acute kidney injury workup algorithm, Acute kidney injury management algorithm

# Overview
Acute Renal Failure is a sudden decrease in kidney function defined as at least one of the following: 1. a definite increase in the serum levels of creatinine of 26.4 mol/L(0.3mg/dl) or more; 2. A proportion increase in the serum levels of creatinine of more than 50% (1.5 fold increase from baseline); or 3. A decrease in the volume of urine output (oliguria 6 hours. The majority of causes of in-hospital acute renal failure is 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 with pre-existing renal impairment.To aid the diagnosis and management, it is important to find out the underlying cause; whether it is pre-renal, renal, or postrenal. Initial workup should be performed as soon as the patient is encountered and any life-threatening situation should be treated promptly.

# Causes

## Life Threatening Causes
Life-threatening causes include conditions that 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

## Common Causes

## Pre Renal Causes
- Hypovolaemia
- Haemorrhage
- Volume depletion(for example vomiting, diarrhea, burns, and inappropriate diuresis)
- Renal hypoperfusion
- Non-steroidal anti-inflammatory drugs/selective cyclo-oxygenase 2 inhibitors
- Angiotension converting enzyme inhibitors/angiotension receptor antagonist
- Abdominal aortic aneurysm
- Renal artery stenosis/occlusion
- Hepatorenal syndrome
- Hypotension
- Cardiogenic shock
- Distributive shock(for example sepsis, anaphylaxis)
- Oedematous States
- Cardiac failure
- Hepatic cirrhosis
- Nephrotic syndrome

## 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
- Drug Induced- Non-steriodal anti-inflammatory drugs, antibiotics
- Infiltrative- Lymphoma
- Granulomatous- Sarcoidosis, Tuberculosis
- Infection related- post-infective, Pyelonephritis
- Tubular injury
- Ischemia- prolonged renal hypoperfusion
- Toxins- drugs(such as aminoglycosides), radiocontrast media, pigments(such as myoglobin), heavy metals (such as cisplatinum)
- Metabolic- hypercalcemia, immunoglobin light chains
- Crystals- urate, oxalate
- Vascular
- Vasculitis(usually associated with antineutrophil cytoplasmic antibody)
- Cryoglobulinaemia
- Polyarteritis nodosa
- Thrombotic microangiopathy
- Cholesterol emboli
- Renal artery thrombosis/renal vein thrombosis

## Post Renal Causes
- Intrinsic
- Intra-luminal- stone, blood clot, papillary necrosis
- Intra-mural- urethral stricture, prostatic hypertrophy or malignancy, bladder tumor, radiation fibrosis
- Extrinsic
- pelvic malignancy
- retroperitoneal fibrosis

# Diagnosis
Shown below is an algorithm summarizing an step by step approach to diagnosis the cause of Acute Renal Failure to aid in the management.
Abbreviations: NSAIDs: Non-steroidal anti-iflammatory drugs; ACE: Angiotensin converting enzyme; ARF: acute renal failure; RRT: Renal replacement therapy; ATN:acute tubular necrosis; ECG:Electrocardiogram

# Treatment
Definitive treatment rely upon the underlying cause; however, the initial approach is directed to manage any life-threatening feature in order to halt or reverse the decline of the renal function, and if unsuccessful, support is provided by renal replacement to aid recovery.
Hyperkalemia, pulmonary edema, and severe acidosis require immediate attention.
Abbreviations: DDAVP: 1-deamino-8-D-arginine vasopressin; DVT: deep venous thrombosis; ARF: acute renal failure; RRT: Renal replacement therapy; I/V:Intravenous

## 1. HYPERKALEMIA TREATMEMT
Severe hyperkalemia is a medical emergency and should be at once treated with infusion of calcium. Infusion of calcium is a temporary management, therefore measures are started to decrease the serum potassium by increasing cellular uptake simultaneously. Overall these steps are enough to normalize the serum potassium; 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 can be started.

## 2. TREATING PULMONARY EDEMA
Excessive fluid therapy can lead to Pulmonary oedema, especially in patients with known cardiac dysfunction, the elderly, and those who were volume replete at the startand can be prevented by judicious intravenous fluid therapy. If respiratory failure ensues, patient should be intubated and mechanical ventilation started. Simultaneouly, pharmacological treatment can be started to disburden the decompensated heart. If these measures fail, hemodialysis or hemofiltration can be used.

## 3. TREATING ACIDOSIS
Variety of mechanisms can cause severe metabolic acidosis (blood pH <7.2) in patients with ARF either due to reduced renal function or due to underlying cause of the patient's illness. Systemic acidosis diminishes cardiac contractility, induces bradycardia, develop vasodilatation, and further expands hyperkalemia. Although there is very little known benefit, Alkaline solution-sodium bicarbonate is administered to reverse acidosis. 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 needed. Haemodialysis or haemofiltration will usually be required to treat severe acidosis in oligoanuric patients.

## 4. OTHER GENERAL MEASURES

# Do's
- 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.

# Don'ts
- Avoid fluid overload.
- Do not use dopamine to increase renal perfusion.
- Cautiously use diuretics if oliguria persists.
- Do not use nephrotoxic drugs (NSAIDs, ACE-I, Aminoglycosides)
- Avoid use of contrast media.