Pediatric IV Fluid Therapy: Historical Perspective and Controversies, Lecture notes of Pediatrics

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P E G G Y P. M C N A U L L , M D A S S I S T A N T P R O F E S S O R , A N E S T H E S I O L O G Y A N D P E D I A T R I C S U N I V E R S I T Y O F N O R T H C A R O L I N A

The Myth of the Third Space

Objectives

 Discuss the origins of IV fluid therapy in children

 Debate the existence of a third space

 Discuss IV fluid therapy and the risks of

postoperative hyponatremia

Intravenous therapy – a historical perspective

 1818 Blundell performed first human to human blood transfusion

 1831 O’Shaughnessy published landmark article in Lancet about fluid and solute deficits in cholera victims

 1832 Latta reported that he had successfully resuscitated numerous moribund cholera patients with intravenous water and salts

Intravenous therapy – a historical perspective

 1918 Blackfan and Maxcy instilled 0.8% saline intraperitoneally to dehydrated infants

 1931 Karelitz and Schick administered D5NS or D5LR intravenously via continuous infusion to dehydrated infants

 1957 Holliday and Segar described the first practical method for the prescription of IV fluids

The third space – fact or fiction

The third space - defined

 Refers to sequestration of fluid in a non-functional extracellular space that is beyond osmotic equilibrium with the vascular space Non-functional extracellular fluid volume (nfECV)

Functional extracellular fluid volume (fECV)

The third space – fact or fiction

Acute change in extracellular fluids associated with major surgical procedures Annals of Surgery, 1961

 13 adults, elective major surgical procedures

 Plasma volume, red blood cell mass, and extracellular

fluid volume (ECV) measured preoperatively and after

two hours of operative time

 Loss of ECV (up to 28%), presumed from internal

redistribution to the third space

 Extracellular fluid volume loss correlated with amount of

observed surgical trauma

The third space – fact or fiction

 Extracellular volume determination via tracer

technique

 Requires suitable tracer  Requires appropriate equilibration time  Requires multiple samples  Requires steady state conditions

The third space – fact or fiction

 Numerous trials report an unchanged or increased

fECV after surgery

 Utilized different tracers (i.e. Bromide)  Calculated fECV from multiple blood samples  Calculated fECV after longer equilibration times

The third space - FICTION

 The classic “third space”

has never been localized

 The classic “third space”

does not exist

 Fluid is shifted within

the functional

extracellular fluid

compartment, from the

intravascular space to the

interstitial space

Functional extracellular fluid volume (fECV)

Perioperative fluid shift - implications

Extracellular fluid volume expansion and third space sequestration at the site of small bowel anastomoses British Journal of Surgery, 1983

 Water content of enteral anastomosis measured in rabbits

 Group 1

 Received no IV fluid therapy  Interstitial water load increased by 5-10%

 Group 2

 Received 5 mL/kg/hr intraoperatively of crystalloid infusion  Interstitial water load double that of Group 1

Perioperative fluid shift - implications

 Surgical trauma increases

the protein permeability of the vascular endothelium  Mechanical stress  Endotoxin exposure  Ischemia-reperfusion injury  Inflammation

 Acute hypervolemia from

liberal fluid therapy alters the endothelial glycocalyx

Effects of intravenous fluid restriction on postoperative complications: Comparison of two perioperative fluid regimens Annals of Surgery, 2003

• Restricted group: significant reduction in postoperative

complications such as anastomotic leakage, pulmonary

edema, pneumonia, and wound infection

Perioperative fluid shift - implications

Postoperative hyponatremia

 Case

 10 yo male trauma patient  Intubated for respiratory distress  Peri-intubation aspiration noted  To OR for left foot ORIF  4 days mechanical ventilation for aspiration PNA  Surgical team prescribed D5 ½ NS post transfer to floor  Rapid response for acute mental status changes  Tonic-clonic seizure while in the CT scanner  Serum Na 116