chapter 47 quiz 3 Perioperative Fluid Management Quiz

81 Questions

What is a characteristic of crystalloids?

They are classified by their overall tonicity after infusion.

Why should administered fluids be considered as drugs according to the text?

Due to their potential side effects.

What distinguishes balanced solutions among crystalloids?

They include a buffer like lactate or acetate.

According to the passage, what percentage of an infused crystalloid solution remains in the intravascular compartment after 30 minutes?

50%

Which of the following statements is true regarding the distribution of crystalloids?

Crystalloids have a larger intravascular volume-expanding effect than previously thought.

What is a potential consequence of large-volume crystalloid infusions?

Dilution of circulating coagulation factors, potentially leading to a hypercoagulable state

Which of the following statements is true regarding the distribution of colloids compared to crystalloids?

Less fluid is ultimately filtered out of the capillary with colloids than with crystalloids.

According to the passage, what is a factor that influences the intravascular volume-expanding effect of crystalloids?

The capillary hydrostatic pressure

Which of the following statements is true regarding the distribution of crystalloid solutions in normovolemic subjects?

Crystalloid solutions may increase tissue edema in compliant tissues.

How does the osmolality of 0.9% NaCl compare to that of plasma?

The same

What happens to the ECF volume after a 2-L infusion of 0.9% NaCl?

Increase

What effect does a 2-L infusion of 0.9% NaCl have on plasma albumin concentration?

Decrease

How does the Na+ and Cl− concentration of 0.9% saline compare to plasma?

Higher

What is the effect of a 2-L infusion of 0.9% NaCl on hematocrit levels?

Decrease

What is a potential side effect seen in healthy volunteers after receiving large-volume (50 mL/kg) saline infusions?

Abdominal discomfort, nausea, and vomiting

In which situation is 0.9% NaCl not suitable for treatment?

Acute severe hyponatremia

What clinical outcome is associated with the use of 0.9% NaCl in the wider critical care population compared to lower Cl− solutions?

Increased incidence of kidney injury

What is a possible use of hypertonic saline solutions mentioned in the passage?

Treatment of hypoosmolar hyponatremia

Why should the volume of saline administered perioperatively be limited according to the text?

Due to potential side effects like renal injury

What distinguishes the effect of 0.9% NaCl from hypertonic saline with regard to intracranial pressure?

Reduces cerebral edema

What was the key distinguishing feature of the early intravenous crystalloid solutions compared to NaCl solutions?

They contained bicarbonate

How do the osmolalities of currently available balanced crystalloid solutions compare to plasma?

They have a lower osmolality than plasma

What is the primary mechanism by which the buffer in balanced crystalloid solutions helps restore bicarbonate levels?

The buffer is metabolized to produce bicarbonate

How do the Na+ and Cl- concentrations of balanced crystalloid solutions compare to 0.9% NaCl?

They have lower Na+ and much lower Cl- concentrations

Why are dextrose solutions considered less suitable for intravascular plasma volume expansion?

Water can move between all fluid compartments.

In what scenario would glucose solutions be coadministered with IV insulin to diabetic patients?

To reduce the risk for hypoglycemia.

What is a potential consequence of using dextrose solutions in the postoperative period?

dilute plasma electrolytes and osmolality.

How do higher concentrations of dextrose serve as a metabolic substrate?

By offering a higher caloric content.

What makes glucose solutions less suitable for intravascular plasma volume expansion compared to other solutions?

Their movement between all fluid compartments.

What is the main fate of acetate when it enters the body?

It is oxidized to yield HCO3

Why is the availability of crystalloids with HCO3 limited?

Due to the diffusion of CO2 out of packaging materials

What can the transient decrease in plasma tonicity after infusion of balanced crystalloids lead to?

Increased excretion of excess water and electrolytes

Why should lactated solutions be avoided in severe liver failure?

Due to impaired metabolism of lactate

What potential negative effects have been identified with acetate-based dialysate?

cardiovascular instability

What are potential manifestations of high acetate levels in patients who receive dialysis with acetate-based fluids?

Nausea, vomiting, and headaches

What is the primary characteristic of colloid particles according to the passage?

They are dispersed in a homogeneous noncrystalline substance

How do the molecular sizes of semisynthetic colloids differ from human albumin solution?

Semisynthetic colloids have a range of molecular sizes

How do colloids differ from pure electrolyte solutions in terms of their effect on transcapillary filtration?

Colloids have a higher COP and minimize transcapillary filtration

What is the initial volume of distribution for colloid molecules above 70 kDa?

The plasma volume

How do colloids differ from crystalloids in terms of their volume-expanding effect?

Colloids have a higher volume-expanding effect than crystalloids

What is a potential limitation of the volume-expanding effect of colloids?

At normal or supranormal capillary pressures, hydrostatic pressure will be increased and transcapillary filtration will occur

What is the primary mechanism by which colloid molecules can be lost from circulation?

All of the above

What is a potential adverse effect associated with the use of semisynthetic colloids in critical care?

All of the above

What is a characteristic of colloids that affects their intravascular retention time?

Higher molecular weight colloids have longer plasma half-lives

What is a potential benefit of colloid infusion mentioned in the passage?

Improved blood rheology and reduced plasma viscosity

What is the primary mechanism by which gelatins are excreted from the body?

Renal filtration

How do the molecular weights of succinylated gelatins and urea-linked gelatins (polygeline) compare?

Succinylated gelatins have a higher molecular weight

Which of the following is a potential negative effect associated with the use of gelatins?

Increased risk of severe anaphylactic/anaphylactoid reactions

What is the primary component from which gelatins are derived?

Bovine collagen

In terms of negative effects, which colloid have the least impact on hemostasis

Gelatins

In terms of negative effects, which colloid have the highest estimated incidence of severe anaphylactic and anaphylactoid reactions

GELATINS

What is the primary determinant of Hydroxyethyl Starches (HES) elimination kinetics?

degree of substitution (DS) and molar substitution (MS) ratio

Which measure defines starches as hetastarches, hexastarches, pentastarches, or tetrastarches based on hydroxyethyl group presence?

Molar substitution (MS) ratio

What does a higher C2/C6 hydroxyethylation ratio indicate about starch metabolism?

Slower metabolism

How is starch size classified based on in vitro MW?

High, medium, and low

What is the primary factor responsible for both the therapeutic volume effects and adverse side effects of starch molecules?

The size of starch molecule

Which characteristic makes smaller HES molecules distinct after administration?

Rapid elimination kinetics

What role does the size of starch molecules play in pharmacokinetics and pharmacodynamics?

Influences both therapeutic volume effects and adverse side effects

Why are smaller Hydroxyethyl Starch (HES) molecules distinct after administration?

formation of a large number of oncotically active molecules

elimination of HES molecules

smaller HES molecules excreted by renal

which of the following fluids have the longer plasma volume effects

HES

starch-related side effects?

all of the above

HES products affect coagulation

The effect is most likely to occur with larger MW or slowly degraded medium MW

HES products affect coagulation through dilutional effects, which patients have the highest risk for bleeding?

patient with sepsis

what is the mechanism of pruritic due to HES products

accumulation in mononuclear phagocyte system, skin, liver, muscle, and gut that may persist for several years

colloids are known to cause side effect such as severe anaphylactoid or anaphylactic reactions. what is the risk in HES products

less than with other colloids

What is the primary concern associated with HES products of medium-to-high molecular weight in critically ill patients with preexisting renal impairment?

Increased creatinine levels

What is the primary mechanism of the antithrombotic effect of dextrans?

Coating of red blood cells leading to inhibition of aggregation

What percentage of a dextran dose is excreted renally within 24 hours?

70%

Which effect makes dextran 40 suitable for use in microvascular surgery according to the passage?

Anticoagulant effect

How are larger molecular weight dextrans primarily degraded in the body?

Degradation by endogenous dextranases in the mononuclear phagocyte system

What is the duration of the plasma volume effect of dextrans?

6 to 12 hours

How dextran molecules can interfere with blood type cross- matching.

by coating the erythrocyte cell membrane

what is the risk for Anaphylactoid reactions with dextrans

intermediate risk

how we can reduce the Anaphylactoid reactions of the dextrans

Preemptive treatment with dextran 1( hapten inhibitor)

what is the mechanism of Renal dysfunction resulting from dextrans

osmotic nephrosis

What is the theoretic risk for transmission of variant Creutzfeldt-Jakob disease and associated bovine spongiform encephalopathy despite preparation techniques in human plasma derivatives?

Undiminished risk even with purification techniques

Why was the early concern that resuscitation with albumin could increase mortality in critical illness debunked?

A large controlled trial found no difference in outcomes between albumin and isotonic saline resuscitation

In what scenario might albumin be associated with an increased incidence of mortality, as mentioned in the text?

Patients with trauma, particularly brain injury

Why is the administration of exogenous albumin not proven to improve outcomes from critical illness according to the text?

Clinical trials showed no benefit in terms of outcomes

Which type of solutions, typically used for volume expansion, have a near-physiologic COP of 20 mm Hg?

Albumin solutions like 5% albumin

Study Notes

Fluids in Perioperative Care

Administered fluids should be considered as drugs with specific indications, cautions, and side effects.
Many fluids available today were developed decades ago without rigorous analysis of their clinical benefits.

Crystalloids

Crystalloids are solutions of electrolytes in water.
Classified by their tonicity after infusion or overall composition.
Examples: 0.9% Sodium Chloride, Balanced Crystalloid Solutions.

0.9% Sodium Chloride

Not clear how it entered routine clinical practice.
Has a Na+ and Cl− concentration far in excess of that of plasma.
Osmolarity is slightly higher than that of plasma.
Can cause hyperchloremic metabolic acidosis and reduced renal perfusion.

Balanced Crystalloid Solutions

Have a lower overall osmolarity than 0.9% NaCl.
Have a lower Na+ concentration and much lower Cl− concentration.
Examples: Lactated Ringer solution, Hartmann's solution.
Metabolism of lactate and gluconate leads to HCO3− production.
Have a more rapid excretion of excess water and electrolyte load compared to 0.9% NaCl.

Hypertonic Saline

Solutions of 1.8%, 3%, and 7.5% NaCl.
Uses: plasma volume expansion, correction of hyponatremia, treatment of increased intracranial pressure.
Can cause endothelial damage at high concentrations.

Dextrose Solutions

Two main indications: as a source of free water and as a metabolic substrate.
5% dextrose is hypotonic with respect to the cell membrane.
Can cause hyponatremia if used excessively.

Colloids

Defined as large molecules or particles of a homogeneous noncrystalline substance.
Examples: gelatins, dextrans, human plasma derivatives.
Increase blood volume by hemodilution, reducing plasma viscosity and red cell aggregation.
Have variable effective plasma half-lives due to filtration, renal filtration, and metabolism.

Gelatins

Derived from bovine collagen.
Modified by succinylation or urea-linkage.
Have a similar molecular weight (MW) but different conformational changes.
Rapidly leave the circulation, predominantly by renal filtration.

Dextrans

Highly branched polysaccharide molecules produced by bacteria.
Available dextrans have an average MW of 40 kDa or 70 kDa.
Rapidly filtered at the glomerulus, with 70% of a dextran dose excreted within 24 hours.
Have a plasma volume effect similar to that of starches, with a duration of 6 to 12 hours.### Human Plasma Derivatives
Human plasma derivatives include human albumin solutions, plasma protein fractions, fresh frozen plasma, and immunoglobulin solution.
These derivatives are relatively purified solutions with the elimination of infective agents.
There is a theoretic risk for transmission of variant Creutzfeldt-Jakob disease and associated bovine spongiform encephalopathy.
One U.K. case of presumed prion transmission has been described in association with factor VIII transfusion, without clinical manifestation.

Human Albumin Solutions

5% albumin solutions have a near-physiologic colloid osmotic pressure (COP) of 20 mm Hg.
These solutions are used for volume expansion.
Despite the association of hypoalbuminemia with worse outcomes from critical illness, the administration of exogenous albumin does not improve outcome in these situations.
Early concerns that resuscitation with albumin may increase mortality in critical illness were not confirmed by a large controlled trial.

Hydroxyethyl Starches (HESs)

HESs are modified natural polymers of amylopectin derived from maize or potato.
The degree of substitution (DS) of hydroxyethyl radicals onto glucose units determines HES elimination kinetics.
An alternative measure of substitution is the molar substitution (MS) ratio.
HESs can be classified as hetastarches (MS 0.7), hexastarches (MS 0.6), pentastarches (MS 0.5), or tetrastarches (MS 0.4).
The pattern of substitution may vary, and a higher C2/C6 hydroxyethylation ratio leads to slower starch metabolism.
HESs are also classified by in vitro molecular weight (MW) into high (450-480 kDa), medium (200 kDa), and low (70 kDa).

Adverse Effects of HESs

HES products with medium-to-high MW are associated with oliguria, increased creatinine, and acute kidney injury in critically ill patients with preexisting renal impairment.
Even newer solutions with low MW (130 kDa/MS 0.4) have been shown to have similar effects on the need for renal replacement therapy in severe sepsis.
The use of starch-based colloids has been restricted or suspended by regulatory authorities in both the United States and Europe.

Test your knowledge on the physiologic effects, indications, cautions, and side effects of fluids administered perioperatively, considering them as drugs with specific properties. Explore the development and analysis of various colloid solutions in clinical practice.

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