Nov 2006 Kishore P.Critical care conference

Renal protective strategies in the ICU

Nov 2006 Kishore P.Critical care conference

Why renal protection?

RIFLE classification of ARF

Crit Care. 2004 Aug;8(4):R204-12

Nov 2006 Kishore P.Critical care conference

Acute renal failure

• 67% of ICU admissions• Mortality

– R-8.8%– I-11.4%, hazard ratio 1.4– F-26.3%, hazard ratio 2.7

• Cost• Technology requirements

Nov 2006 Kishore P.Critical care conference

Prevention is better than cureDesiderius Erasmus

Nov 2006 Kishore P.Critical care conference

Causes of ARF in the ICU

• Primary disease activity• Shock states• Sepsis syndromes• Infections-malaria, scrub, leptospirosis• Nephrotoxic drugs• Contrast nephropathy• Vascular-anastomotic, athero and

cholesterol embolisation

Nov 2006 Kishore P.Critical care conference

Renal protection - general

• Ensure adequate renal perfusion• Avoid / minimize use of nephrotoxic drugs

including radio contrast• Early recognition and aggressive

management of sepsis

Nov 2006 Kishore P.Critical care conference

Adequate renal perfusion

Nov 2006 Kishore P.Critical care conference

Adequate renal perfusion

• Blood pressure• Intravascular volume• Cardiac output• Other markers of perfusion

Nov 2006 Kishore P.Critical care conference

Scenarios

1. 60 year old lady presented with urosepsis to the casualty. She had not passed urine for the last 6 hours. Blood pressure on arrival was 60mmHg systolic. She was catheterized and 50ml of urine was drained. 1 liter of crystalloids is rushed in and dopamine is started-BP picks up to 100/40mmHg. She reaches ICU after 2 hours. The MAP is 64mmHg. She is treated with 1 liter of Haesteril, and output increases to 45ml per hour for the next hour, and gradually trails off. Her creatinine is 1.5, and goes up to 3.2 the next day.

Nov 2006 Kishore P.Critical care conference

1. A 76 year old female undergoes a sigmoid colectomy for ruptured diverticulum. Her baseline blood pressure is 140/80, MAP 100mmHg. She requires multiple boluses of phenylephrine in the operating room to support her blood pressure. On return to intensive care, the patient is mechanically ventilated. Her urinary output is 15ml in the first hour.

She is treated with 1 litre of colloid, her CVP rises to 14cmH2O, she puts out little urine, and her blood pressure remains 90/50 mmHg (MAP 63). The registrar starts a noradrenaline infusion, targeted at a MAP of >80mmHg, and the patient’s urinary output increases to 70 to 100ml/hour. Over the next 48 hours, each time the vasopressor was weaned and the MAP fell below 75mmHg, so too did the urinary output. Eventually, the patients blood pressure recovers, and she is weaned from ventilation and vasopressors without further difficulty.

Nov 2006 Kishore P.Critical care conference

• Renal Autoregulation • Renal Medullary Hypoxia • Tubuloglomerular Feedback

CCM tutorials.com

CCM tutorials.com

Nov 2006 Kishore P.Critical care conference

Blood pressure

• Renal autoregulation suboptimal below 80 and lost below 60mmHg

• Renal success Vs renal failure

Nov 2006 Kishore P.Critical care conference

Blood pressure

• Target MAP of 70mmHg normally in ICU• 80mmHg in patients with oliguria,

established renal failure, longstanding hypertensives and raised ICP

Nov 2006 Kishore P.Critical care conference

Intravascular volume

• Target CVP of at least 14-16mmHg• Fill till signs of overfill just manifest

– CVP>16mmHg– Drop in P/F ratio– Bilateral crackles– S3– Loss of stroke volume variation

• Fill to targets, do not go by numbers!

Nov 2006 Kishore P.Critical care conference

CO and other markers of perfusion

• Cardiac output assessment• Urine output• Base excess and lactate• ScvO2

Nov 2006 Kishore P.Critical care conference

Sepsis syndromes

Nov 2006 Kishore P.Critical care conference

Renal failure in sepsis

• Shock• Cytokine damage• DIC• Drug induced

Nov 2006 Kishore P.Critical care conference

• Principles of optimizing renal perfusion• Specific measures

– Low dose dopamine– Fenoldopam– Dopexamine– Intensive insulin therapy– Ischemic preconditioning

Nov 2006 Kishore P.Critical care conference

Low dose dopamine

• Renal dose-2.5mcg/kg/min-renal vasodilation

• Meta-analysis: low-dose dopamine increases urine output but does not prevent renal dysfunction or death.

• Can actually worsen renal perfusion• No role.

Ann Intern Med. 2005 Apr 5;142(7):510-24 Kidney Int. 2006 May;69(9):1669-74

Nov 2006 Kishore P.Critical care conference

Fenoldopam

• Dopamine-1 receptor agonist• Selective renal vasodilation• Many small trials. Evidence inconclusive• Recent RCT - did not show significant

reduction in renal failure with Fenoldopam

Crit Care Med. 2005 Nov;33(11):2451-6

Nov 2006 Kishore P.Critical care conference

Dopexamine

• Beta2 and dopamine agonist - inodilator• Not useful

British Journal of Anaesthesia 2005 94(4):459-467

Nov 2006 Kishore P.Critical care conference

Intensive insulin therapy

• Intensive insulin therapy in the SICU to maintain capillary sugars between 80-100mg/dl reduced acute renal failure requiring dialysis or hemofiltration by 41 percent

• However subsequent study in the MICU did not support this. However new onset rise in creatinine was reduced (12.6 vs 8.3%). No difference in dialysis requirement.

N Engl J Med. 2001 Nov 8;345(19):1359-67 N Engl J Med. 2006 Feb 2;354(5):449-61

Nov 2006 Kishore P.Critical care conference

Nephrotoxic drugs

Nov 2006 Kishore P.Critical care conference

• NSAIDs• ACE inhibitors • Aminoglycosides• Last straw• Consider alternatives• Weigh risk vs benefit

Nov 2006 Kishore P.Critical care conference

Contrast• Incidence of contrast nephropathy 2% in non-

critically ill patients• Rise in s.creat. By 0.5mg% or a 25% increase

from baseline 48-72 hours after contrast exposure

• Is contrast really necessary?• Non ionic contrast• Hydration• N-acetyl cysteine• NaHCO3• Fenoldopam• Ascorbic acid, theophylline

Nov 2006 Kishore P.Critical care conference

Hydration

• Most effective stand alone intervention• 1000-2000 ml in the 12 hours prior to the

procedure

Clin Nephrol. 2004 Jul;62(1):1-7

Nov 2006 Kishore P.Critical care conference

N-acetyl cysteine

• RCTs show inconsistent results• Meta-analyses – show benefit• 2gms over 6 hours

Clin Cardiol. 2004 Nov;27(11):607-10

Nov 2006 Kishore P.Critical care conference

Bicarbonate

• Better than saline alone• 3ml/kg/hr 1 hour before procedure

followed by 1ml/kg/hr for 6 hrs after

JAMA. 2004 May 19;291(19):2328-34

Nov 2006 Kishore P.Critical care conference

• Hemodialysis and filtration in pre-existing renal failure

Nov 2006 Kishore P.Critical care conference

Specific situations

• Rhabdomyolysis: 10% mannitol and hydration to maintain urine output 100ml/hr

• Cholesterol embolisation- care during cath procedures

Nov 2006 Kishore P.Critical care conference

Oliguria in the ICU

• Rule out obstn, abdominal compartment syndrome

• BP, volume, CO target optimisation• Diuretics only if all above fulfilled

Nov 2006 Kishore P.Critical care conference

Organ preference

• Prefer the lung to the kidneys – do not fill the kidneys and flood the lungs

The superior doctor prevents sickness; The mediocre doctor attends to

impending sickness; The inferior doctor treats actual

sickness;Chinese proverb