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Endocrine - Dr Troutman > Quiz 1 - Endocrine and Thermoregulation > Flashcards

Quiz 1 - Endocrine and Thermoregulation Flashcards

1
Q

What is a hormone?

A

substance which is created by one type of cell that signals a response from another type of cell.

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2
Q

What are some different types of hormones?

A
  • Peptides and protein hormones
  • Thyroid hormones
  • Catecholemines
  • Steroid hormones
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3
Q

Can hormones act on any cell?

A

No, they need to have the correct receptor

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4
Q

Where are cell receptors for hormones located?

A

Can be on the surface or within the cell

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5
Q

What regulates the number of hormone receptors on a cell?

A

the cell’s response to a hormone is what regulates the number of receptors on a cell.

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6
Q

What feedback mechanism controls most hormone activity? Positive or Negative feedback?

A

Negative feedback

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7
Q

What does homeothermic indicate?

A

temperature range between 36.5 - 37.3 degrees celsius

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8
Q

When monitoring temperature - in relation to core temperature, how much does the skin temp vary from the core?

A

May be 3-4 degrees C cooler

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9
Q

How does the Axillary temp vary from core temp?

A

axillary temp may be 1 degree C cooler

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10
Q

What are some sites for core temp measuring?

A
  • rectum
  • esophagus
  • Nasopharynx (can create epistaxis)
  • External auditory meatus (risk of TM rupture)
  • Bladder cath
  • Pulm Art Cath
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11
Q

What is considered hypothermic?

A

core temp less than 36 degrees C

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12
Q

What is considered hyperthermic?

A

core temp more than 38 degrees C

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13
Q

What is considered normothermic?

A

37 degress C +/- 1 degree C

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14
Q

Where is temperature regulated in the brain?

A

Hypothalamus and preoptic nuclei

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15
Q

What are some of the vascular effects of hypothermia?

A

Vasoconstriction, hypoperfusion, difficult pulse ox readings

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16
Q

What are some of the cardiac effects of hypothermia?

A

Shivering can increase oxygen consumption by up to 300%

Also causes increased incidence of MI, arrhythmias and cardiac morbidity. VF occurs around 22-23 degrees C

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17
Q

What are some of the pulmonary effects of hypothermia?

A

PVR increases, decreased ventilatory drive, decreased CO2 in blood

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18
Q

Effects of hypothermia on renal

A

Cold diuresis –> decreased plasma volume

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19
Q

effects of hypothermia on hepatic

A

decreased hepatic blood flow

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20
Q

effects of hypothermia on CNS

A
  • CMO2 consumption decreases 7% for each 1 degree C decrease. MAC decreases 5-7% for each 1 degree C change, drowsiness, confusion
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21
Q

effects of hypothermia on hematologic

A

Impaired platelet function, decreased platelet count, decreased activity of coagulation factors

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22
Q

effects of hypothermia on metabolism

A

reduced by 50% at 30 degrees C, slows drug metabolism, prolong NM blockade, delayed emergence, prolonged elimination of inhalation agents, increased concentrations in plasma of propofol and fentanyl

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23
Q

effects of hypothermia on healing

A
  • increased healing time leads to increased incidence of wound infection.
  • vasoconstriction leads to poor tissue perfusion.
  • less penetration of antibiotics to sites.
  • Decreased phagocytic activity.
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24
Q

For body temp, what are the 2 compartments and what is the fraction of body temp in both compartments?

A
  • Peripheral compartment (1/3 of heat): Skin, limbs, sub Q tissues
  • Core compartment (2/3 of heat): major thoracic and abdominal organs and brain
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25
Q

How are the temperature differences between the core and peripheral compartments maintained?

A

through vasoconstriction

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26
Q

How much heat production would you created if you were completely insulated from heat loss?

A

1-2 degrees Celsius per hour

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27
Q

How much can shivering increase heat production?

A

by 300%

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28
Q

T/F Under normal conditions, body heat is preserved by tonic peripheral vasoconstriction

A

True

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29
Q

What is the major means of heat loss?

A

Radiation - accounts for 60% heat loss

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30
Q

T/F: Convection can account for 25% of heat loss in OR’s with forced airflow.

A

True

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31
Q

T/F: Normal respiration of inspired gases can account for evaporative losses.

A

True

32
Q

How much does conduction contribute to heat loss?

A

< 5%

33
Q

How is core body temperature regulated?

A

Peripheral vasoconstriction

34
Q

T/F: Can general and regional anesthesia inhibit peripheral vasoconstriction

A

True

35
Q

How much does the core body temperature decrease after the 1st hour?

A

1 to 1.5 Celsius

36
Q

How much can one unit of refrigerated blood or one liter of room temperature crystalloid decrease core body temperature?

A

0.25 Celsius

37
Q

How much does basal metabolic rate decrease each year beyond the age of 30?

A

1 %

38
Q

As to which age group has the greatest increases surface to mass resulting in rapid heat loss to environment?

A

Neonate

39
Q

T/F: Minor shivering in patient in preop is acceptable to warm the patient.

A

FALSE

40
Q

Shivering is induced by ________ of the preoptic region of the _____________ which causes the involuntary oscillatory muscular activity.

A

cooling, hypothalamus

41
Q

Why is Meperidine most commonly used for post operative shivering?

A
  • Effective
  • Partially mediated by kappa opioid receptors
  • Decreases shivering threshold twice as much as vasoconstriction threshold
42
Q

What are some causes of hyperthermia?

A
  • malignant hyperthermia
  • sepsis/infection
  • thyrotoxicosis
  • pheochromocytoma
  • hypothalamic lesion,trauma, anoxia
  • Neuroleptic malignant syndrome
  • transfusion reaction
  • medication
43
Q

What is occurring with a patient that manifests with hypercatabolic state with tachycardia, hypercapnia, muscle rigidity, tachyarrythmias, metabolic acidosis.

A

Malignant hyperthermia

44
Q

What would be given preoperative to control hyperthermia?

A

Acetominophen

45
Q

What would be done to control hyperthermia intraoperative.

A
  • Cooling the OR
  • Forced air cooling
  • cooled IV fluids
  • Field irrigation with cold fluids
  • NG, Bladder irrigation with cooled fluids
46
Q

What occurs with infection/sepsis to result in hypothermia?

A

During bacteremia, pyogens cause release of INTERLEUKIN ONE, increasing the set point for temperature in the hypothalamus.

47
Q

What are some facts about post op shivering?

A
  • Occurs in 40% of unwarmed patient after general anesthesia
  • Causes dramatic increases in oxygen consumption and catecholamine release
  • 3 times increase in myocardial events.
48
Q

What are the 4 divisions of the pituitary called?

A
  1. Adenohypophysis (anterior)
    2 Pars Intermedius (gone after fetal develops)
    3 Pars tubularis (vascular but no hormones)
    4 Neurohypophysis (posterior)
49
Q

Where does the pituitary gland rest?

A

in the Sella Tursica in the sphenoid bone

50
Q

What does the anterior pituitary (adenohypophyis) regulate?

A

Thyroid, adrenals, mammary glands, growth hormone, gonads and melanocytes

51
Q

What are the cells in the anterior pituitary that secrete growth hormones?

A

Somatotropes (most abundant)

52
Q

What are the cells called that secrete adenocorticotropic Hormone (ACTH)

A

Corticotropes

53
Q

What do the gonadotropes in the anterior pituitary secrete?

A 
Luteinizing Hormone (LH)
Follicular Stimulating Hormone (FSH)
54
Q

What are the cells in the anterior pituitary that secrete ProLactin (PL)?

A

Lactotropes

55
Q

What are the two hormones that are secreted by the posterior pituitary (neurohypophysis)?

A

Oxytocin and vasopressin

56
Q

Where are hormones synthesized? Where are they secreted?

A

Hormones are synthesized in the HYPOTHALAMUS and transported intracellularly for secretion from the PITUITARY

57
Q

What is the dominant site for vasopressin (ADH) synthesis?

A

Supraoptic nucleus

58
Q

There are two receptors for vasopressin (V1 and V2). What are their effects when stimulated?

A

V1 - pressor effect

V2 - ADH effect

59
Q

What stimulates the release of vasopressin?

A

plasma osm > 290

60
Q

What are some signs of SIADH?

A

Water retention yields a low serum Na, dilute plasma and concentrated urine

61
Q

What are some causes of SIADH?

A

CNS disorders, cold stress, trauma, drug induced, squamous cell lung CA

62
Q

How should you treat SIADH?

A

find the cause, LIMIT FLUID INTAKE

63
Q

At what level of Na would you expect to start seeing symptoms of hyponatremia?

A

125 meq/L - serious symptoms below 120 meq/L

64
Q

What are some mild, mod, and severe hyponatremia problems?

A

Mild - anorexia, nausea, weakness
Mod - lethargy, confusion
Severe - Seizures, coma, death

65
Q

A sodium at what level would be considered safe for surgery and unsafe for surgery?

A

Above 130 - SAFE

Below 130 - may lead to cerebral edema

66
Q

Should you correct hyponatremia quickly or slowly? Why?

A

SLOWLY - rapid correction could lead to CENTRAL PONTINE MYLINOLYSIS

67
Q

What is Diabetes Insipidus (DI)?

A

Inability to release ADH (central) or inability to respond to ADH (renal).
Central is most common

68
Q

What are some signs/symptoms of DI?

A

Polydipsia and Polyuria without hyperglycemia. H2O intake keeps these pts from severe dehydration.

69
Q

How is DI treated?

A

Central - ADH nasal spray (desmopressin)

Renal - demeclocycline

70
Q

Anesthetic implications for DI

A
  • Increased MAC due to decreased uptake of inhalation agents from decreased CO.
  • Hypovolemia requires large doses of IV agents
  • postpone elective surgery for Na > 150
71
Q

Should you correct hypernatremia quickly or slowly?

A

SLOWLY - rapid correction results in seizures, brain edema, permanent neuro damage and death

72
Q

Where in the posterior pituitary is oxytocin produced?

A

Supraoptic Nucleus

73
Q

How do you mix oxytocin?

A

20 units to 1 liter crystalloid and titrate to uterine contractions

74
Q

What is a common sign of pituitary tumor?

A

Loss of peripheral vision due to compression of optic chiasm.
Can also manifest as systemic effects due to hormonal changes.

75
Q

What are some anesthesia complications due to pre-existing hormonal disorders?

A

Acromegaly (GH) - difficult airway
Hyperthyroid (TSH) - tachycardia, weight loss
Cushing disease (ACTH) - difficult airway and access (?)
Panhypopituitaryism - hormone replacement with cortisol, levothyroxine, DDAVP

76
Q

Pt’s having a transsphenoidal resection of the pituitary may develop DI what are some implications with this?

A
  • Could be temporary or permanent
  • May be evident intraop or postop
  • Suspect with high urine output
  • Confirmed with spec gravity < 1.005
  • *Treat with DDAVP 0.5 -1mcg IV or SQ plus volume replacement

Endocrine - Dr Troutman (7 decks)

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