This has not appeared in the past papers. However, the great Competencies document makes mention of it. Thus, if an SAQ ever came up on this topic, it might ask the candidates to "Discuss the features which identify patients at risk of developing ARF, and discuss some of the therapies that may have prophylactic benefits." Or perhaps "Discuss the influence of ARF on the morbidity and mortality of ICU patients",  which sounds like some sort of creative writing task. Question 29 from the first paper of 2005 has some vague relationship with prevention of ARF, but it is in context of AAA repair, and more closely related to rhabdomyolysis and contrast-induced nephropathy.

Patient population at risk of developing acute renal failure in the ICU:

A famous and widely cited study by De Mendonça et al (2000) contains within it tables of comparison, which relate the risk factors for developing acute renal failure in the ICU, as well as risk factors for developing all kinds of other organ failure once renal failure is already established. These tables look something like this:

Risk Factors for Renal Failure in the ICU
Risk factor Odds rato

Age over 65

1.5

Infection on admission

1.52

Cardiovascular failure

1.84

Cirrhosis

2.18

Respiratory failure

1.44

Chronic heart failure

2.18

Haematological malignancy

2.23

In addition to these, one can also add

  • Cardiac surgery patients
  • Survivors of cardiac arrest
  • Patients with pre-existing renal failure

Influence of renal failure on ICU morbidity

In other words, "How does the presence of acute renal failure influence the risk of failure of other organ systems?"

Risk Factors for Renal Failure turning into MOSF
Risk factor Odds rato

Cardiovascular failure

15.5

Liver failure

9.06

Coagulopathy

6.23

Delirium

4.14

Age over 65

1.19

Chronic heart failure

2.27

Prevention of acute renal failure in the ICU

There is a good, reasonably recent (2017) reference for this subject matter. Michael Joannidis et al performed a thorough literature search and generated a list of recommendations, graded by the strength of the evidence.

There are several general strategies which can be employed.

In addition to these, there are specific protective strategies which are helpful in specific conditions, for example in the case of contrast-induced nephropathy. The specific strategies are discussed in greater detail in other sections; this brief summary will only mention them in passing.

Generic strategies to prevent renal failure

The strategies suggested by OH's Manual:

  • Maintain a haemoglobin over 70
  • Rapidly ensure intravascular volume is adequate
  • Achieve satisfactory haemodynamic parameters (eg. a MAP of 70mmHg in most people)

Additional strategies suggested by other sources

Specific strategies to prevent renal failure in specific at-risk groups

  • In chronically hypertensive septic patients, aim for a higher MAP (eg. 75-80mmg), according to Asfar et al (2014)
  • To prevent contrast-induced nephropathy, use a range of effective strategies (discussed elsewhere)
  • In pre-op cardiothoracic patients at risk of AKI, consider fenoldopam (Landoni et al, 2007)

Strategies which we know to be ineffective:

  • Diuretics in the prevention or management of renal failure
  • Low-dose dopamine
  • Natriuretic peptides

References