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Foundations of Anesthesia 1 > Fluids, Electrolytes-Nagelhout Ch 21 > Flashcards

Fluids, Electrolytes-Nagelhout Ch 21 Flashcards

1
Q

What tissues have a slight positive Interstitial Fluid Pressure-Pif (usually slightly negative)?

A

Rigid or encapsulated tissues such as:
Kidneys
Brain
Bone Marrow
and Skeletal Muscle

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2
Q

What is the primary determinant of both plasma oncotic (πp) and interstitial oncotic pressure (πif)? Why?

A

Albumin. Small molecular weight and a higher concentration than other plasma proteins.

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3
Q

Increases in capillary hydrostatic pressure (Pc) and Interstitial Oncotic Pressure (πif) favor fluid filtration into the?

A

Interstitial space.
Pc pushes fluid out of intravascular space
πif pulls it out of intravascular space

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4
Q

Increases in the Interstitial Fluid Pressure (Pif) and Plasma Oncotic Pressure (πp) favor fluid filtration into the?

A

Intravascular space.
Pif pushes fluid out into intravascular space
πp pulls fluid into the intravascular space

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5
Q

What is “Pif”

A

Interstitial Fluid Pressure

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6
Q

What is “πif”

A

Interstitial Oncotic Pressure

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7
Q

What is “πp”

A

Plasma Oncotic Pressure

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8
Q

What is “Pc”

A

Plasma (capillary) hydrostatic pressure

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9
Q

Positive Net Filtration favors fluid exudation into the?

A

tissues

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10
Q

Negative Net Filtration favors fluid absorption into the?

A

vasculature

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11
Q

Describe the overall balance of filtration pressures within the body

A

Arterial end capillaries tend to be slightly positive
Venous end capillaries tend to be slightly negative.
The overall balance is slightly positive, with a small percent of intravascular volume constantly filtering into interstitial space under normal conditions

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12
Q

Within the interstitial space, fluid movement from the interstitial space into and out of the cell occurs via?

A

Osmosis

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13
Q

Which electrolyte is a primary determinant of serum osmolality and water transport, thus making ECV dependent on it?

A

Sodium

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13
Q

Normal daily alterations in TBW are regulated by:

A

RASS
ADH
and Atrial natriuretic system (ANP)

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14
Q

How does RASS regulate sodium hemostasis?

A
  1. Cardiac and renal baroreceptors detect hypotension.
  2. Juxtaglomerular cells in kidneys release Renin.
  3. Renin is the precursor for cleaving angiotensin I into active form
  4. Angiotensin I exerts local vasoconstriction but is the primary precursor for Angiotensin II
  5. Angiotensin-converting enzyme converts angiotensin I into Angiotensin II in the lungs
  6. Angiotensin II is a potent vasoconstrictor and directly stimulates renal tubules to reabsorb sodium and water.
  7. Agt II also causes the adrenal cortex to release aldosterone, which further stimulates sodium and water retention by the kidneys
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15
Q

What does RASS regulate compared to ADH

A

RASS regulates sodium hemostasis
ADH functions primarily to regulate water balance

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16
Q

How does ADH regulate water balance

A
  1. Slight increases in serum osmo are detected by osmoreceptors in the hypothalamus
  2. Posterior Pituitary Gland releases ADH, and the hypothalamus stimulates thirst
  3. This causes kidneys to open aquaporin channels within the kidney to reabsorb large water volume
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17
Q

How does ADH play a role in blood pressure?

A

Decreases in circulating volume detected by baroreceptors stimulate ADH release. Potent vasoconstrictor.

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18
Q

How does Atrial Natriuretic Peptide (ANP) reduce intravascular volume?

A
  1. Stretch receptors in cardiac atria release ANP when preload or hypervolemic state is detected.
  2. This stimulates kidneys to release sodium and water into urine to reduce blood volume.

Additionally, it increases GFR and inhibits renin and ADH release.

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19
Q

Due to low molecular weight, crystalloid solutions contribute to the hemodilution of plasma proteins, which leads to a decrease in which transcapillary pressure?

A

Plasma Oncotic Pressure
πp

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20
Q

Approximately what percent of administered isotonic crystalloids filter into the interstitial space?

A

~75-80% once the oncotic pressures are at equilibrium on both sides of the membrane

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21
Q

Normal Saline 0.9% is slightly hyper or hypo osmolar?

A

Hyper ~310osmo

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22
Q

Lactated Ringers-LR is slightly hyper or hypo osmolar?

A

Hypo ~275osmo

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23
Q

How does the concentration of sodium and chloride compare in Normal Saline

A

Equal concentrations. (Even though this is not physiologically normal)

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24
Q

What can occur if Normal Saline is used for acute volume resuscitation?

A

High chloride load in NS can contribute to dose-dependent hyperchloremic metabolic acidosis. pH may be maintained but with large alterations in base excess.

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25
Q

Hypercholoremia has a substantial impact in?

A

Renal Function
leading to a decrease in GFR and may also impair the renal handling of bicarbonate.

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26
Q

The increased sodium load introduced by large volumes of NS can cause:

A

Increased salt and water retention
Hemodilution
Interstitial edema
well into post-op period

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27
Q

In small volumes in neurosurgical patients, which isotonic fluid is preferred for patients at risk for cerebral edema?

A

0.9% NS due to its mild hyperosmolality

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28
Q

In patients with anuria and end-stage renal disease, which isotonic fluid may benefit the patient more?

A

0.9% NS due to having no potassium in the solution.

29
Q

What fluid solution is used in low-dose infusions in trauma and head-injured patients? Why?

A

Hypertonic Saline Solutions of 3% or greater.
Promote volume expansion that mobilize intracellular and interstitial fluid into the vascular space. May protect patients with intracranial hypertension.

30
Q

What are some risks of hypertonic saline solution administration?

A

-Vascular Irritation
-Sudden and pronounced fluid shift into the intravascular space
-Potential for dehydration of neural cells leading to osmotic demyelination syndrome

31
Q

What patient population should not receive LR for large-volume fluid resuscitation? Why?

A

Diabetic patients.
Byproducts of the hepatic metabolism of LR can result in gluconeogenesis.

32
Q

LR is contraindicated in patients with? Why?

A

Traumatic brain injury or other neurovascular insults
Bc LR is mildly hypotonic. Can cause transient hypo serum osmo and associated cerebral edema

33
Q

Can Plasmalyte-A, Normosol-R, and Isolyte S be used for blood administration?

A

Yes. They do not contain calcium.

34
Q

How do colloids produce intravascular volume expansion?

A

By directly increasing plasma oncotic (πp) pressure and interacting with the endothelial glycocalyx to decrease transcapillary filtration.

35
Q

What are Dextrans?

A

Oldest artificial colloids
Possess high molecular weight polymers derived from bacterial metabolism of sucrose

36
Q

Dextrans are no longer used in clinical practice due to?

A

Causing acute renal failure
Inducing anaphylaxis and coagulopathy

37
Q

What are hydroxyethyl starches (HES)?

A

Synthetic macromolecules derived from starchy plants including potatoes, maize, and sorghum

38
Q

First-generation HES are the highest molecular weight and have been associated with?

A

Dose-dependent coagulopathy because of hemodilution and binding of clotting factors, interference with platelet adhesion,
inhibition of fibrin chain formation,
and alterations in plasma viscosity

39
Q

How can HES cause severe pruritus and nephrotoxicity?

A

Can accumulate to form interstitial colloid deposits in subcutaneous tissue and other organs

40
Q

RCTs have demonstrated what risks associated with HES use?

A

Kidney injury
Dialysis requirements
coagulopathy
sepsis
and increased mortality

41
Q

Small volumes of albumin provide a ______ degree of intravascular resuscitation as compared to equal or greater volumes of crystalloid

A

Greater

42
Q

Albumin does carry a risk of?

A

Anaphylaxis and other immune-mediated reactions

43
Q

What is the Donnan effect?

A

Albumin molecules bind ions, which increases the plasma osmolarity and intravascular volume

44
Q

Stimulation of somatic and autonomic afferent nerves in the area of surgical incision triggers the activation of what feedback system?

A

Hypothalamic-Pituitary Axis (HPA)

45
Q

As a result of CNS activation, the hypothalamus releases?

A

Corticotropin-releasing hormone which prompts the anterior pituitary gland to secrete adrenocorticotropic hormone (ACTH).

46
Q

Secretion of adrenocorticotropic hormone (ACTH) elicits what?

A

The creation and release of cortisol from the adrenal cortex.

47
Q

What are some functions of cortisol?

A
  1. Stimulates protein catabolism
  2. Hepatic gluconeogenesis and glycogenolysis
  3. Increased hepatic production and release of plasma proteins
48
Q

What effect does the activation of the HPA and, ultimately, the release of cortisol have on fluid balance?

A

Maintain energy substrate levels and contribute to increased plasma oncotic (πp) pressure to help preserve intravascular volume

49
Q

Hyperglycemia is a major risk factor for:

A

Damage or destruction of the endothelial glycocalyx. It also impairs wound healing, contributes to osmotic diuresis, and interferes with immune responses.

50
Q

You should consider canceling surgery if the patient’s serum sodium level is ____ or less

A

130

51
Q

What are some effects of catecholamine release due to surgical trauma stimulation of sympathetic nerves?

A

-Increased HR
-Increased SVR
-Microcirculatory vasoconstriction
-Increased metabolic rate and increased oxygen demand

52
Q

Surgical trauma and tissue injury stimulate endothelial release of cytokines and other inflammatory mediators, what effects does this have?

A

Contribute to hyperthermia, increased oxygen demand, and regional changes in microcirculatory flow

53
Q

What are some benefits of low-levels of cytokine release?

A

promotes local hemostasis and migration of neutrophils to site of injury

54
Q

Prolonged or unrestricted cytokine and immune mediators can have negative effects such as?

A

Vasodilation / Hypotension
Endothelial Damage (think glycocaylx)
Increased filtration and tissue edema
Insulin resistance
Intravascular loss
Decreased organ perfusion

55
Q

What is one of the most beneficial effects of cortisol regarding inflammation?

A

Profound anti-inflammatory effects. Inhibiting production, release, and vascular aggregation of inflammatory mediators.

56
Q

During periods of hypovolemia or hemorrhage, decreased plasma hydrostatic pressure (Pc) favors?

A

Absorption of fluid from the interstitial space into the intravascular space.

57
Q

While Laparoscopic surgery has many benefits, what are some associated risks?

A

Increased intra-abdominal pressure
Transient splanchnic ischemia - risk for reperfusion injury
Vagal Response if pressure rises too quick or too high greater than12-15mmHG

58
Q

Insufflation has what effects on venous circulation

A

Significant increase in CVP from shunting - can lead to release of ANP OR
Reduce preload by decreasing venous return. If pt is already hypovolemic - could cause cardiac collapse.

59
Q

Insufflation has what effects on arterial circulation

A

Afterload markedly increased due to increased intrathoracic pressure. Contributes to lower SV.
MAP is often elevated.
Ejection fraction is reduced

60
Q

What are 3 anesthetics medications / techniques that can help reduce the effects of insufflation needed for laparoscopic procedures?

A

Opioids and Dex are known to be effective at reducing HPA mediated stress responses.

Neuraxial anesthesia helps mitigate spinal cord transmission of autonomic afferent impulses to HPA

61
Q

ERAS stands for?

A

Enhanced Recovery After Surgery

62
Q

Goal Directed Fluid Therapy (GDFT) often begin by?

A

A baseline assessment of target hemodynamic values followed by a 200-250ml fluid bolus to assess patients position along the Starling Curve.

63
Q

The Frank-Starling mechanism is the relationship between?

A

Left-Ventricular End Diastolic Pressure (LVEDP) and Stroke Volume (SV)

64
Q

Pulse contour analysis provides dynamic measures of preload responsiveness by quantifying ?

A

The degree of change of arterial, capnography, or pulse oximetry waveforms associated with respiratory variations and the resulting pleural pressures.

65
Q

Why is the degree of stroke volume variation more prominent during hypovolemia?

A
  1. Increased intrathoracic pressure from positive pressure ventilation decreases RV filling
  2. Greater inspiratory impact on RV afterload if alveolar pressure exceeds pulmonary arterial and venous pressures impeding RV ejection
  3. Greater ventricular contractility in response to LV preload “bolus” if the patient is on the ascending portion of the Frank Starling curve.
66
Q

Pulse contour analysis predicts fluid responsiveness if calculated value is greater than what percent?

A

13%

67
Q

Clear fluids can be administered up to how many hours before surgery?

A

2 hours

68
Q

ASA standards now recommend how many hours prior to surgery can a patient have a light meal? Heavy meal?

A

6 hours light

8 hours heavy

69
Q
A

Foundations of Anesthesia 1 (29 decks)

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