Chapter 169 - Crystalloids Versus Colloids Flashcards
Body water : quantity and repartition ?
Total body water is approximately 60% of body weight.
Two-thirds of this water (66%) is intracellular, while the remaining 33% is extracellular (2/3 (∼25% total body water) is interstitial; 1/3 (∼8% of total body water) intravascular)
Crystalloids: repartition and timing?
Approximately 80% of the volume infused leaves the intravascular space (IVS) within 1 hour of administration). The predominant effect of crystalloids is expansion of the interstitial space.
Normosol and Plasma-Lyte : electolytes, buffers and use ?
Normosol and Plasma-Lyte contain potassium and magnesium, and are buffered by acetate and/or gluconate (Table 169.1). These solutions are appropriate for extracellular volume (ECV) repletion.
0.9% sodium chlorid (isotonic saline) : historical indications ?
Fluid of choice as a calciuretic in patients with hypercalcemia, for correction of hypochloremic metabolic alkalosis, and for co-administration with citrated blood products to avoid clot formation.
Negative effects of 0.9% sodium chloride ?
0.9% sodium chloride is unbalanced and contains a supraphysiological concentration of chloride. Chloride-rich fluids have also been associated with detrimental renal effects and possibly worse outcomes
in sick humans.
Saline infusion compared to balanced solution:
- decreased renal artery flow velocity and renal cortical perfusion in healthy people
- increased incidence of acute kidney injury (AKI) and need for renal replacement therapy (RRT) in sick people
- increased postoperative infections, blood transfusion requirements, and mortality
Saline or balanced electrolytes solutions in cats with urethral obstruction ?
2 studies: both investigations concluded that while these solutions were equally safe and effective, balanced electrolyte solutions (Normosol-R, LRS) led to more rapid normalization of acid–base status.
Difference between maintenance and replacement fluids ? Which are more appropriate for fluid resuscitation and why?
Maintenance crystalloids (e.g. Normosol-M + 5% dextrose, Plasma-Lyte-M) contain less sodium and more potassium than replacement fluids. Maintenance and hypotonic fluids are not appropriate for resuscitative purposes, as rapid or large-volume administration can result in acute hyponatremia and/or cell swelling and lysis that can be fatal.
Positive effects of hypertonic saline?
Positive effects of hypertonic saline?
- PV-expanding effects
- Vascular smooth muscle relaxation and arteriolar vasodilation,
- Lower blood viscosity,
- Reduced endothelial cell swelling
- Improved regional blood flow
- Beneficial cardiac effects: increased cardiac output and improved coronary perfusion.
- Increased PV results in reflex cerebral vessel vasoconstriction and subsequent reduced intracranial volume.
- Favorable immunological effects
Type of colloids?
Synthetic colloids include hydroxyethyl starches (HES), dextrans, and gelatins. Natural colloids: plasma, albumins.
Does human albumin in human patients influence mortality?
Patients treated with albumin had a higher MAP and lower net fluid balance, but neither a mortality difference nor a difference in total administered fluid volume was found between groups.
Most significant adverse effects of HES?
- coagulopathies,
- AKI,
- tissue accumulation,
- trends towards increased mortality
- Increased postoperative bleeding tendencies and transfusion requirements
The use of HES solutions is currently banned in Europe and Surviving Sepsis Campaign guidelines recommend against the use of HES for fluid resuscitation of patients with severe sepsis and septic shock
Principle of hypotensive resuscitation?
Aggressive fluid therapy may exacerbate bleeding in trauma patients with uncontrolled haemorrhage.
Hypotensive resuscitation involves targeting lower than normal BP (mean arterial BP and systolic
BP of 50–60 mmHg and 80–90 mmHg, respectively) that support vital organ perfusion but are less likely to exacerbate bleeding from dilution or clot dislodgement.
FEAST trial: found that boluses of either albumin or saline (versus no bolus) to severely ill and hypotensive African children increased 48-hour mortality.
