Critical care: organ failures (acute and chronic)

Question 1

What is the definition of AKI?

Answer 1

Acute Kidney Injury aka Acute renal failure

A rapid deterioration in renal excretory function and GFR characterised by an impairment of electrolyte, EC volume and acid:base homeostasis

Question 2

What are the parameters for staging AKI?

Answer 2

Stage 1:
- UO < 0.5ml/kg/hr > 6hrs or eGFR > 25% fall over 7 days or absolute increase in serum creatinine > 26umol/l over 48hrs or a 50% increase in creatinine from baseline

Stage 2:
- UO < 0.5ml/kg/hr > 12 hrs or serum creatinine 2-3x baseline

Stage 3:
UO < 0.3ml/kg/hr > 24 hrs or serum creatinine > 354 umol/l or 3x baseline

Question 3

What are the causes of AKI? Categorise your answer (3)

Answer 3

1. Pre-renal:
   - Hypovolaemia secondary to HF, diarrhoea, vomiting, fluid or blood loss
   - Renal artery stenosis or occlusion (partial or complete)
   - Nephrotoxic drugs - NSAIDs, ACEi, diuretics, paracetamol
2. Renal:
   - Glomerulonephritis
   - Acute tubular necrosis secondary to sepsis, toxins
   - Acute instistial nephritis
   - Sepsis
   - Thrombotic microangiopathy (HUS)
3. Post-renal
   - Tumour
   - Stone
   - Prostate enlargement

Question 4

What are the clinical features of AKI?

Answer 4

Typically asymptomatic but as failure develops:

1. Peripheral and pulmonary oedema (crackles)
2. Decreased UO - oliguria, anuria
3. Vomiting, diarrhoea + anorexia
4. Arrhythmias (due to hyperkalaemia)
5. Myalgia, arthralgia, malaise, confusion

Question 5

What are the key investigations for AKI patients?

Answer 5

1. Urine
   a. dip - blood (infection, renal damage); nitrates, WCC (infection); ketones (DKA)
   b. Microscopy
   - red cell casts = glomerulonephritis
   - granular casts = ATN
   - eosinophils = AIN
   - pence-jones = myeloma
2. Bloods
   a. U+E = ^urea ^creatinine ^K+ ^Ca2+
   b. FBC = ^WCC (if infection), low Hb (if bleed), low platelets (liver disease), raised platelets (vasculitis)
   c. ESR/CRP^ in vasculitis
3. Blood Gas = metabolic acidosis (pH <7.35, HCO3- < 22)
4. USS - conduct in 24hrs if no obvious cause for deterioration

Question 6

What are the key treatments for AKI?

tip: think fluid, electrolytes, acid:base imbalances

Answer 6

1. ABCDE
2. Fluid balance:
   a. Hypo? –> 500ml saline or Hartmann’s over 30mins
   b. Hyper? –> Supportive therapy with oxygen, can also consider IV nitrates
3. Hyperkalaemia:
   a. Calcium gluconate 10ml 10% IV bolus - repeat every 20 mins
   b. Salbutamol nebs
   c. 10 units of Actrapid in 50mls of 50% dextrose over 20 mins
   d. haemodialysis if no improvement
4. Metabolic acidosis:
   a. IV Bicarbonate 50-100ml 8.4% IV over 30 mins

Monitor U+Es, UO, fluid volume, acid:base balance (blood gas)

Question 7

What is the criteria for considering renal replacement therapy i.e. haemodialysis, haemofiltration, peritoneal dialysis

Answer 7

1. Persistant Hyperkalaemia
2. Persistant metabolic acidosis pH < 7.1, HCO30 < 12
3. Uraemic pericarditis
4. Encephalopathy
5. Creatinine > 700 aprox
6. Symptomatic uraemia - tremor, cognitive imp, coma, fits, urea > 45mmol/L
7. Fluid + salt loss

Question 8

What is the criteria for classifying a patient with CKD?

Answer 8

A permanent impairment of renal anatomy or function > 3months or a GFR < 60ml/min/1.73 > 3 months

Question 9

What are the causes of CKD?

Answer 9

1. Type 2 DM (poorly controlled)
2. Glomerulonephritis due to IgA nephropathy or vasculitis
3. Renal artery stenosis, pyelonephritis, reflux nephropathy

Question 10

What are the symptoms of CKD?

Answer 10

Nocturia, polyuria, nausea, vomiting, anorexia, fatigue, malaise, uraemic skin (yellow tinge), pallor,

Signs of fluid overload
Facial oedema, gum hypertrophy, ballotable kidney, dyspnoea (pulmonary oedema),

Question 11

What are the key investigative findings for CKD?

Answer 11

1. Bloods
   a. eGFR < 60ml/min/1.73
   b. Urea < 7.8mmol/L
2. Urine
   a. ACR > 3 (mild); 3-30 (mod); > 30 (sev)
3. USS if severe CKD (Stage 4/5), refractory HTN or haematuria

Question 12

What is the correction for afro-carribean eGFR level?

Answer 12

CKD-EPI i.e. eGFR x 1.2

Question 13

What are the grades of CKD based on eGFR?

Answer 13

Normal > 90 
1 = 90 
2 = 89-60
3a 59-45 
3b. 44-30
4 < 30 
5 < 15

Question 14

What is the key long term treatments for CKD?

Answer 14

1. Anti-HTN control (aim for < 140/90)
   a. ACEi or ARB or renin inhibitors if CKD and: DM + ACR 3, HTN + ACR 30, ACR > 70
2. Statin - Atorvastatin
3. Anticoagulation - Apixaban if eGFR 30-50 + AF + stroke RF

Question 15

in a CKD patient how can you manage the following:

a. Fluid overload
b. Anaemia
c. Osteomalacia
d. Acidosis

Answer 15

a. Furosemide (low dose)
b. Folic acid or B12 injections (if deficient) or recombinant EPO (if EP deficient)
c. Zolindronic acid or bisphosphanates if severe
d. IV bicarbonate 8.3% 50-100mls IV over 30mins

Question 16

What are the common complications of CKD?

Answer 16

1. Fluid overload
2. Acidosis
3. Anaemia due to B12/Folate or EPO deficiency
4. Osteomalacia and renal bone disease

Question 17

How can you spot deterioration in CKD?

Answer 17

sustained eGFR fall of > 25% per year or change in eGFR category or
sustained eGFR fall of > 15ml/min/1.73 over a year