This document discusses the concept of "third space" fluid shifts during surgery and argues that the third space may not exist as traditionally conceived. It notes several studies that found patients gained up to 10kg after surgery, indicating overcorrection of fluid deficits. The document discusses how fluid overload can damage the endothelial glycocalyx and cause pulmonary and tissue edema. It argues that most fluid administered shifts into the interstitial space rather than a hypothetical "third space." Maintaining the integrity of the endothelial glycocalyx may be important to prevent perioperative fluid shifting. Judicious use of crystalloids and colloids is recommended to avoid third space shifting and overloading.

1. Dr S.N.Bhagirath,

2. The Dilemma..!
3rd
Space
Then where is all
the fluid
administered going
to..?
3rd
Space
Then why is
it so difficult
to quantify
it..?

3. Over – estimated fluid deficit due to preoperative fasting
Lamke LO Nilsson GE & Reithner HL1977
Over – estimated fluid deficit due to Insensible losses
Virgilio RW, Rice CL, Smith DE
Proof of overcorrection – weight gain upto 10Kgs
Dawidson IJ, Willms CD, Sandor ZF et al
Proof of overcorrection – weight gain upto 10Kgs
1979
1991
Jacob M, Chappell D, Conzen2008
Third Space
?

4. Traditional Concepts
Preoperatively fasted
patient – hypovolemic
After fasting –
ECV slightly
decreases
Intravascular
volume remains
within normal
range
Insensible loss – dramatic loss
Basal
Evaporative
loss –
0.5mL/Kg/hr
1 mL/kg/hr
during large
abdominal
surgeries
Fluid shift into third space –
needs substitution
Overload is not a problem –
Kidneys can manage..!
???
!!!

5. Intraoperative fluid dynamics

6. Overcorrection leading to weight gain..!
Peak of fluid shifting at 5 hrs after trauma and persists up to 72 hrs
depending on location and duration of surgery.
Lowell et al. found 40% of patient admitted to SICU had an
excessive increase in body water of more than 10% of preoperative
weight.

8. Hypervolemic loading with crystalloids:
 Physiologically distribute within the ECV.
 4/5 will leave the vasculature.
Hypervolemic loading with colloids:
 60% do not remain in the vasculature
due to volume effect.
Fluid Shift

10. What does this
overloading imply..?

11. Endothelial Glycocalyx
Healthy
vascular
endothelium
coated by
endothelial
glycocalyx – a
layer of
membrane-
bound
proteoglycans
and
glycoproteins.

12. Fluid shift into the interstitial space can be
divided into two types:
Type 1 – physiologic shift.
-- Colloid-free fluid and electrolytes.
Type 2 – pathologic shift.
-- Protein-rich fluids.
-- Functionally altered vascular barrier.
Endothelial Glycocalyx

13. Endothelial Glycocalyx
Type 2 shift, result of 2 intraoperative factors.
Surgical:
Endothelial damage due to mechanical
stress, endotoxin exposure, ischemia-reperfusion
injury and SIRS.
Iatrogenic: Acute hypervolemia!

15. Effects of overloading (even with colloids)
Damaged Endothelial Glycocalyx manifests as
•Delayed wound healing
•Tissue edema
•Pulmonary edema
•Anastomotic leakage
Exercise caution in overloading (even if it is not crystalloids..)

16. Is it accumulating in the third space…..?
• Described as non-anatomical..?!!!
• Except for one study, and even that with sulphur and bromide
tracers, no other tracer study has shown the third space to exist
• Are tracers really reliable..?
What are the considerations weighing against them..?
So, Where is all this overcorrection accumulating..?
If so, where is this third space….?

17. •The selection of a suitable tracer which distributed exclusively in
the third space
•How long one ought to wait till the tracer has distributed
exclusively in the third space before it begins redistributing
elsewhere?
•How does one validate the method adopted to quantify this third
space?
•The requirement of a steady state condition necessary for a
tracer to function optimally rules out states of hemodynamic
shock or even surgical stress which defeats the purpose wholly.

18. •Settings of hypotension or hypovolemia prolong equilibration of
the tracer causing more of it to remain in the plasma rather than
the third space.
•Sequestration of the above preferred tracers inside the
erythrocytes, plasma components and subsequent accumulation
in liver and kidney further alienates its efficacy.

19. Something to do with fluid shift
mechanics….perhaps….
There exists a gradient across the vessel and the interstitium, with
the intravascular compartment having a high hydrostatic pressure
as opposed to a low hydrostatic pressure in the Interstitium.
This calls for a substantial inwardly acting colloidal osmotic
pressure intravascularly to counter the hydrostatic pressure
gradient.
In this setting, if one were to transfuse iso-oncotic colloids, they
would not change the intravascular colloid osmotic pressure.

20. On the contrary, if one were to transfuse crystalloids, since they
would not exert any colloid osmotic pressure, there is no inwardly
acting force to keep them trapped within the vascular
compartment. i.e. crystalloids readily cross the vascular barrier
into the interstitium as opposed to their colloidal counterparts.
Administration of crystalloids in a normovolemic patient does not
therefore increase the intravascular volume.
Consequently, preloading a patient prior to anaesthesia with
crystalloids ill serves the purpose of preventing intraoperative
hypotension secondary to anaesthesia15, 16.

21. In summary, in a normovolemic patient – infused colloid tends to
remain intravascularly and infused crystalloid tends to cross over
into the interstitium
How long does this dictum hold good…?
After a certain limit, once infusion of colloids leads to a relative
state of hypervolemia, strangely enough, the colloidal fluid
hitherto trapped intravascularly begins to cross over into the
interstitium.

22. Volume depletion secondary to normal preoperative fasting is
insignificant
Volume depletion secondary to fasting is significant only if a bowel
wash has been administered, dehydrated patients and
hypovolaemic patients.
Preloading with crystalloids before administration of anesthesia as
routine practice is best reconsidered.
Generous fluid replacement intraoperatively does more harm than
good to the patient.
Volume replacement based on only urinary output is best avoided.
Use colloids judiciously.

23. Protection or restoration of this endothelial glycocalyx might be an
important therapeutic goal.
prevent perioperative fluid shifting - judicious use of crystalloids
and colloids as necessary
avoid third space shifting. (if you still believe it exists)
In Summary

24. ?

25. Bruegger D, Jacob M, Rehm M et al. Atrial natriuretic peptide induces shedding of endothelial
glycocalyx in coronary vascular bed of guinea pig hearts. American Journal of Physiology. Heart
and Circulatory Physiology 2005; 289:H1993–H1999.
Jacob M, Chappell D, Conzen P et al. Blood volume is normal after preoperative overnight
fasting. Acta Anaesthesiologica Scandinavica 2008; 52: 522–529
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