46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
91
Fluid management tips
The ultimate goal is to ensure that the intravascular compartment has enough
volume to preserve the ventricular-vascular coupling dynamic. The restoration of the
intravascular compartment is of paramount importance, and thus, the fluid deficit
within this compartment should be replaced as rapidly as possible. However, total
body water loss (dehydration) should be replaced over 24 to 48 hours (Tranquilli et
al. 2007). Excessive fluid transfusion (overhydration) is just as dangerous as
inadequate fluid replacement. Immediate goals are to restore the intravascular
compartment.
It is best to obtain a venous blood samples as soon as possible, preferably before
aggressive fluid management. These venous blood samples may be used to determine
the best type of fluid to use in the initial intravascular compartment replacement
strategy. The following tests may be of help:
1. Venous blood gas analysis – acid/base, electrolyte (Na+, Cl-, Ca2+), ScvcO2, BE,
HCO32. Haematocrit
3. Total serum proteins (helpful to get Albumin to Globulin ratio)
Based on clinical presentation the clinician can draft an effective fluid management
plan prior to induction of anaesthesia (Boesch 2013, Cook et al. 2003, Belli et al.
2013, Boscan et al. 2007, Snyder et al. 2013). In general, if the peripheral pulses do
not feel adequate (good tone and bound) then induction of anaesthesia should be
delayed until there is adequate circulating volume. Up to half of all patients will not
respond to fluid treatment with a drop in the heart rate, these patients are called
non-responders. This could be due to pain, increased and sustained sympathetic
tone, or ineffective fluid management. Fluid selection should be based on the amount
of time available to restore the circulating volume and the composition of the fluid
loss. Very broad fluid selection guidelines include:
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Hypoproteinemia: more synthetic colloid than isotonic crystalloid
Anaemia: more synthetic colloid [consider blood products or oxyglobin
(Soma et al. 2005) if haematocrit is < 25%] than isotonic crystalloid.
Remember that Hb is a critical participant in O2 transport and CaO2!
Raised protein and haematocrit: isotonic crystalloids
Severely dehydrated (10 to 15% estimated total body water loss): Caution
hypertonic saline! Use isotonic crystalloids and synthetic colloids rather.
Horse must get to theatre immediately: Consider hypertonic saline (7.2%)
bolus (1 to 4 mL/kg) to improve circulating volume before induction
(Gasthuys et al. 1994). The deficit should be replaced during maintenance of
general anaesthesia.
During general anaesthesia: a minimum fluid rate in colic operation is
generally 10 to 30 mL/kg/hr (Boesch. 2013, Cook et al. 2003). This rate is not
easily achieved, large bore catheters, multiple catheters placed in superficial
veins, and 10 drops/mL admin sets may be used to attain these rates. This
rate is designed to ensure replacement of losses such as evaporation from
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