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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