Fluids in ICUJMO teaching 5th July 2016

Objectives• Physiology of fluid infusion

• History of fluid resuscitation

• Physiology of fluid resuscitation

• Types of resuscitation fluid

• The ideal resuscitation fluid

• Fluid overload and how to avoid it

Physiology of fluid infusion

• What are the effects of rapid infusion of a litre of 5% dextrose into a patient?

Physiology of fluid infusion

• What are the effects of rapid infusion of a litre of 0.9% saline (Normal saline) into a patient?

Physiology of fluid infusion

• What are the effects of rapid infusion of a litre of 5% normal serum albumin solution into a patient?

Physiology of fluid infusion

• Which of the 3 infusions would be excreted the quickest and why?

History of fluid resuscitation

• 1832 = Robert Lewis administered “Saline injections into the vines” vs cholera pandemic

“… the quantity necessary to be infected will probably be found to depend upon the quantity of serum lost; the object being to place the patient in nearly his ordinary state as to the quantity of blood circulating in the vessels”

History of fluid resuscitation

• Sidney Ringer (1834-1910) developed solution 1884

• Alexis Hartmann (1989-1964) modified solution by addition of lactate

• 1941 => blood fractionation => development of Albumin … used at Pearl Harbour same year

Physiology of fluid resuscitation

• Target = restore intravascular volume

• NB: in concert & equilibrium with cardiac output

• Forget the microcirculation at your peril!

• Glycocalyx increasingly recognised to be essential to normal capillary membrane permeability

• Destruction by inflammation, sepsis, surgery etc…

Physiology of fluid resuscitation

Types of resuscitation fluid

Colloids

• Albumin

• HES (10%, 6%)

• Synthetic starch

Crystalloids

• 0.9% saline

• Hartman’s / CSL

• Plasmalyte

NB: huge variation in global use of these solutions

Ideal resuscitation fluid• Predictable response

• Sustained increase in intravascular volume

• Truely balanced vs ECF

• Metabolised and exerted without accumulation

• No adverse metabolic or systemic effects

• Cheap

• NB: this does not exists currently

Albumin• Reference colloid solution

• Fractionation blood => heat treated

Advantages:

• Safe

• Not as much coagulopathy / renal failure as other colloids

Disadvantages:

• Expensive (not so much in Australia)

• Limited availability in low/middle income countries

• Short shelf life (~1yr)

Albumin• 1998 Cochrane meta-analysis, 24 trials,1419 patients, albumin vs

N/S in hypovolaemia, burns and hypovolaemia => increased mortality (6% increase in absolute risk of death)

• SAFE trial (NEJM, 2004): MRCT, n = 6997, vs 28 day mortality, powered for 3% absolute reduction in mortality

• 4% albumin ‘safe’ compared to normal saline

• Post hoc analysis = TBI and major trauma had worse outcomes with albumin and patients with septic shock tended to better with albumin.

• Martin (CCM, 2005) = pts hypoproteinaemic with ARDS given albumin + frusemide vs frusemide alone => improved oxygenation & CVS stability

AlbuminAn approach …

• Use in

• Spontaneous bacterial peritonitis

• Early resuscitation of ICU patients esp sepsis (further studies pending)

• ARDS in patients with low albumin with frusemide

• NOT to be used in TBI

• ???

• To correct hypoalbuminaemia (<20)

0.9% NaCl• Isotonic

• Not that ‘normal’

• Adverse effects

• Hyperchloraemic metabolic acidosis (strong ion difference = 0)

• Immune and renal dysfunction

0.9% NaCl

• vs HES

• CHEST (NEJM 2012): MRCT, 7000 pts, no significant difference in mortality at 90 days

• HES => pruritus and 21% relative increase in RRT

Plasmalyte solution• Not truely ‘balanced’

• Recommended first line in surgery, DKA, burns, ? trauma

• Single centre trials indicate significant decrease in rate of major complications, infections, CRRT, transfusions

• Adverse effects

• Metabolic alkalosis

• Hyperlactaemia

• Hypotonic (low Na+)

• Micro thrombi (Ca2+ with citrate containing blood transfusions)

• Large RCT about to start …

Fluid administration

• How do you decide to administer a fluid bolus?

• What measures do you use to predict fluid responsiveness?

Fluid administration

• What are the adverse effects of excessive fluid administration?

Recommendations

Recommendations

Thank you …• Myburgh JA, Mythen MG. Resuscitation Fluids.

N Engl J Med. 2013 Sep 26;369(13):1243–51.

• Ogbu OC, Murphy DJ, Martin GS. How to avoid fluid overload. Curr Opin Crit Care. 2015 Aug;21(4):315–21.

• CICM part II exams

• “The physiology viva” Kerry Brandis (2003)