Question 10

A 78-year-old patient has been admitted to your ICU with septic shock of unknown cause. Background medical history includes type 2 diabetes and a prior stroke.

Laboratory tests show the following change in renal indices:

Baseline

      On admission

Adult Normal Range

Urea

15 mmol/L*

          32 mmol/L*

3.0-8.0

Creatinine       

150 µmol/L*

          380 µmol/L*

45-90

1) Outline your approach to the assessment of the acute kidney injury in this patient (4 marks)

2)Outline your approach to the management of the acute kidney injury in this patient. (6 marks)

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College Answer

Syllabus topic/section:

2.1.7 Renal Intensive Care – L1.

Aim:

To examine the understanding of renal failure secondary to sepsis and allow demonstration of strategies to avoid this complication.

Discussion:
Candidates who performed well divided their time and answer depth appropriate to the marks allocated. Candidates who referred to the scenario outlined, and then organised their answer accordingly, with specific rationale for assessment and management scored well. The topic is core to daily intensive care practice, and thus some detail (outlining rather than generic listing) of the important assessment and management facets for the patient was expected.


For example, the stem outlined a patient with acute AND chronic renal impairment and this aspect will guide the assessment and management. A prioritised approach to investigations, (instead of a catch all generic list) coupled with detailed goals of therapy, gained more marks.
Writing “Give fluids” or “aim euvolaemia” without mentioning how the clinical goal would be achieved gained less marks.

Consideration of poor cardiac output is an important contributor to AKI in ICU. Acknowledgement of this and addressing this in the management would have improved many candidates' answers. Many candidates spent far longer on assessment (4 marks) than the management section (6 marks) . Details on when and where dialysis was appropriate would have gained more marks than a generic list of indications.

Despite the stem mentioning septic shock of unknown cause many did not address assessment of source, source control issues and antibiotic choice with renal considerations in drug dosage.

12.1.1 - Assessment (4 marks)

History

Little to no specific history relevant to renal failure

0 marks

Covers basics but without perspective or detail.

E.g. fails to consider aetiology of underlying renal impairment.

0.5 marks

Aetiology of chronic and acute renal impairment. ID reversible causes.

Obstructive or infective symptoms, nephrotoxins esop medications. Seek info from nephrologists if possible likely to be seeing one with baseline CR).

0.5-1 marks

Examination

Generic with little to no renal focus.

0 marks

Covers basics but without perspective and detail.

E.g. fails to consider aetiology of underlying renal impairment.

0.5 marks

In depth with masses renal tenderness, prostate.

CVS signs detailed re shock, BP perfusion, details of volume status.

1 mark

Investigation

Generic answer with little or no renal specific investigation.

<0.5 marks

Basics of urinalysis, renal and CVS interrogation but lacking in full diagnostic detail or clinical perspective.

0.5- 1.5 marks

Urinalysis (inc sediment and micro). Imaging and contrast guide. (e.g. if infarction)

Prioritised list of investigations with rationale.

1.5-2 marks

12.1.2

Management

Generic answer major errors.

<2 marks

Safe approach with any systemic organisation of facts.

g, pre-renal, e.g. fluid discussion with Hb targets.

Renal. E.g. pharmacology Postrenal. Details of procedures.

2-3 marks

All the previous and

  • r/o and mx reversible causes.
  • ABs and drugs (evidence summary) with renal adjustments specified.
  • understands nuances of volume status.
  • Tx Sepsis. Consideration of CVS targets and why.

4-6 marks

(6 marks)

Overall organisation to be considered in the marking

Poor structure and /or failure to address the specifics relevant to the renal impairment.

A safe and structured approach but missing some detail or clinical perspective.

Clear systematic and detailed approach to diagnosis and management with a focus on renal failure.

Additional clinical perspective indicating an understanding of balancing the clinically common whilst considering less common

but important issues.

Discussion

The detailed notes by the college and the marking rubric have made it easy to craft a model answer which contains the kitchen sink, but much harder to fit everything into ten minutes. What follows is a 258-word answer which would hopefully have passed this SAQ, even though it exceeds the 1600-character ten minute limit.

Assessment:

  • History
    • Chronic renal failure history (hypertension, diabetes, etc)
    • Drug history (nephrotoxins, antibiotics, NSAIDs, ACE-Is, etc)
    • Family history (eg. polycystic kidney disease)
    • Social / occupational history (eg. substance abuse)
    • Recent infections / exposure (eg. strep throat, enteritis, etc)
    • Autoimmune disease (myalgias, GI motility issues, joint aches, random rash, haemoptysis)
  • Examination
    • Volume assessment
    • Kidney ballottability, size (polycystic?), flank tenderness (pyelonephritis?), renal artery bruits
    • Contributing diseases: CCF, liver failure, ascites, organomegaly, malignancy
    • Search for systemic features of autoimmune disease (eg. lupus, dermatomyositis)
  • Biochemistry
    • Electrolytes, ABG, - for complications of AKI
    • Blood film, CK level, eosinophil count, EPG/IEPG, vasculitis screen (to exclude rare causes of renal failure)
    • Urine (culture, protein, analysis for light chains, microscopy of the sediment)
  • Imaging
    • Ultrasound (renal artery stenosis, rebnal vein thrombosis, parenchyma, and obviously pelvocalyceal diltataion)
    • CT KUB (to rule out renal calculi and hydronephrosis/pyelonephritis)
    • TTE, to quantify the contribution from poor cardiac output

Management

  • Underlying cause (sepsis)
    • Source control
    • Broad spectrum antibiotics with dose adjustment, chosen for their nephrofriendly toxicity profile
  • Optimising the environment for renal recovery
    • Volume resuscitation / vasopressors / inotropes 
    • Aim for a MAP > 75 if chronically hypertensive
    • Serial reassessment 
  • Prevention of progression to renal replacement therapy
    • Restriction of nephrotoxins
    • Medical therapy for metabolic acidosis and hyperkalemia
    • Trial of diuretics and/or CPAP to temporise fluid overload
  • Timing and character of renal replacement therapy
    • If pt. meets absolute criteria (eg. hyperkalemia refractory to medical management) or remains oliguric for > 72 hrs with urea rising to > 40 mmol/L (based on AKIKI-2 findings)
    • CRRT with citrate if pt. remains shocked, or SLED if the haemodynamics permit

References

Gaudry, Stéphane, et al. "Comparison of two delayed strategies for renal replacement therapy initiation for severe acute kidney injury (AKIKI 2): a multicentre, open-label, randomised, controlled trial." The Lancet 397.10281 (2021): 1293-1300.

indell, Joseph A., and Glenn M. Chertow. "A practical approach to acute renal failure." Medical Clinics of North America 81.3 (1997): 731-748.

Sladen, Robert N. "Oliguria in the ICU: systematic approach to diagnosis and treatment." Anesthesiology Clinics of North America 18.4 (2000): 739-752.

Asfar, Pierre, et al. "High versus low blood-pressure target in patients with septic shock." New England Journal of Medicine 370.17 (2014): 1583-1593.