Surgical Indications for the Obese Flashcards

1
Q

What percentage of adults in the US are considered obese?

A

65%

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2
Q

What percentage of adolescents and children are obese in the US?

A

15%

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3
Q

What is a determining factor in development of co-morbidities related to weight?

A

BMI

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4
Q

At what BMI is a patient considered low risk for developing co-morbidities?

A

BMI of 25-30

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5
Q

At what BMI is a patient considered high risk for developing co-morbidities?

A

BMI greater than 40

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6
Q

What percentage of anesthetic incidents involve obesity as a contributing factor?

A

50%

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7
Q

What were majority of the closed claims extubation or recovery claims related to?

A

Difficult intubation on induction, obesity or OSA

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8
Q

What is the most practical way to figure out IBW?

A

Broca’s index:
Male: IBW = ht (cm) - 100
Female IBW = ht (cm) -105

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9
Q

What is the formula to calculate a patient’s BMI?

A

Quetelet’s Index

weight in kg) / (height in meters squared

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10
Q

What does ideal body weight tell us?

A

Measurement of height compared to body mass

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11
Q

What does the NIH consider as a Grade I obese patient?

A

BMI 26-29.9

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12
Q

What does the NIH consider as a Grade II obese patient?

A

BMI 30-39.9

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13
Q

What does the NIH consider as a Grade III obese patient?

A

BMI greater than 40

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14
Q

What is considered a normal BMI?

A

BMI 24-26

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15
Q

What is considered mild obesity?

A

BMI 27-30

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16
Q

What is considered moderate obesity?

A

BMI 31-35

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17
Q

What is considered severe/morbid obesity?

A

BMI greater than 35

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18
Q

What is considered super morbid obesity?

A

BMI greater than 55

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19
Q

What are the two type of obesity?

A

Android “Apple”

Gynecoid “Pear”

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20
Q

How does a patient with android obesity present?

A

Significant weight above the waist, especially in the face and neck
The adipose is centrally deposited

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21
Q

How does a patient with gynecoid obesity present?

A

Weight is carried below the waist

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22
Q

What is a more efficient predictor of mortality than BMI or waist circumference alone?

A

Fat distribution

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23
Q

What is considered low, moderate and high risk in females based on their waist to hip ratios?

A

Low: 0.8
Moderate: 0.81-0.85
High: 0.85 and up

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24
Q

What is considered low, moderate and high risk in males based on their waist to hip ratios?

A

Low: 0.95
Moderate: 0.96-1
High: 1 and up

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25
Q

What medical risks are associated with android fat distribution?

A

Increased myocardial fat content
Ischemic hear disease
NIDDM
Stroke

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26
Q

What medical risks are associated with gynecoid fat distribution?

A

Varicose veins
Degenerative joint disease
Fat metabolically static

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27
Q

What gender is android fat distribution typically seen in?

A

Males

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28
Q

What can occur when free fatty acids are delivered to the liver?

A

Stimulation of hepatic synthesis of VLDL and increased circulation of LDL
Glyconeogenesis and inhibition of insulin uptake –> NIDDM

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29
Q

Define concentric hypertrophy.

A

Increased wall thickness and diminished volume

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30
Q

Define eccentric hypertrophy.

A

Myocardial volume increases more than wall thickness

31
Q

How does concentric hypertrophy form?

A

Increased demand causes remodeling of the heart, cardiac fibroblasts produce interstitial collagen

32
Q

How does the heart function in a lean, normotensive patient?

A

Preload and after load are balanced

33
Q

How does the heart change in a lean but hypertensive patient?

A

Increased after load = increased wall thickness and diminished volume which leads to concentric hypertrophy

34
Q

How does the heart change in an obese but normotensive patient?

A

Increased preload = myocardial volume increases more than wall thickness

35
Q

How does the heart change in an obese hypertensive patient?

A

Increased preload and after load with periods of hypoxemia = LV dilation and wall stress leading to eccentric and concentric changes

36
Q

Which cardiac changes are seen more clearly in an obese hypertensive patient?

A

Concentric more than eccentric

37
Q

How much does CO increase with body fat?

A

0.1L/kg of fat to deliver blood at a rate of 2-3mL/100g tissue

38
Q

What co-morbidities are associates with a obese, hypoxic individual?

A

Obesity + hypoxia leads to heart disease and increased risk of sudden death

39
Q

Where is blood redirected when a patient’s BMI is greater than 40?

A

20% greater to splenic blood flow to feed intestines

40
Q

What type of lung disease is often seen in obese patients?

A

Restrictive lung disease
thoracic kyphosis
lumbar lordosis

41
Q

What syndrome can occur with worsening obesity and OSA?

A

Pickwickian Syndrome

42
Q

What are the signs of Pickwickian syndrome?

A
Hypercarbia
Hypoxemis
Polycythemia
Pulmonary HTN
Biventricular failure
43
Q

What can result from worsening obesity-hypoventilation syndrome?

A

Loss of hypercarbic drive
Hypersomnolence
Increased DAW

44
Q

How does obesity affect the GI system?

A

High gastric volumes, acidity and decreased GI motility

45
Q

What are the characteristics of metabolic syndrome?

A

Obesity
HTN (high cholesterol and lipids)
DM II Insulin resistance

46
Q

How does obesity affect the kidneys?

A

Increases renal clearance of drugs due to increased renal blood flow and increased GFR

47
Q

What type of malignancies are associated with obesity?

A
Breast
Prostate
Colorectal
Cervical/Endometrial
Ovarian
48
Q

What is a skin condition that is highly associated with insulin resistance?

A

Acanthosis Nigricans (skin folds and creases)

49
Q

What tow skin conditions frequently occur in an obese patient?

A

Intertrigo-reddened rash

Carbuncles-clusters of boils

50
Q

What condition can occur in the obese patient that has signs and symptoms associated with a brain tumor but no tumor is present?

A

Idiopathic Intracranial HTN (pseudotumor cerebri)

51
Q

What is meralgia paeasthetica?

A

Entrapment of femoral cutaneous nerve at inguinal ligament, get numbness and tingling

52
Q

Is morbid obesity considered an independent risk factor for sudden death from acute postoperative PE?

A

Yes

53
Q

How much heparin should be administered to an obese patient after surgery based on ASBS guidelines?

A

5000u SQ for 12h

54
Q

When should a patient stop smoking prior to surgery?

A

At least 6 weeks

55
Q

What degree of reverse T-berg is useful during induction of an obese patient?

A

Greater than 30 degrees

56
Q

What are common nerve injuries in an obese patient?

A

Brachial plexus stretch
Sciatic nerve palsy
Ulnar neuropathy

57
Q

Why are the obese more prone to nerve injuries?

A

Poor perfusion

58
Q

How should propofol be dose in an obese patient?

A

Induction: IBW
Maintenance: TBW

59
Q

How should Fentanyl be dose in an obese patient?

A

TBW

60
Q

How should remifentanil be dose in an obese patient?

A

IBW

61
Q

How should succinylcholine be dose in an obese patient?

A

TBW

62
Q

How should vet, roc and atra be dose in an obese patient?

A

IBW

63
Q

Why is nitrous oxide useful in the obese population?

A

Fat insoluble
Rapid onset
Minimal metabolism

64
Q

Why isn’t nitrous used at much in the obese population?

A

Limites due to higher FiO2 needed to maintain PaO2

65
Q

What is the oil gas partition coefficient for Sevoflurane?

A

47

66
Q

What is the oil gas partition coefficient for Desflurane?

A

19

67
Q

How should the estimated blood volume be calculated in an obese patient?

A

45-55ml/kg actual body weight

68
Q

What is the goal in volume replacement of an obese patient?

A

Euvolemia

69
Q

What is the percentage of total body in an average adult compared to an obese adult?

A

Normal: 60-65%
Obese: 40%

70
Q

How does the EBV differ in an obese patient compared to an averaged sized adult?

A

EBV is actually decreased despite increased circulatory fluid volume

71
Q

What is an appropriate tidal volume for an obese patient?

A

10-15mL/kg based on IBW

72
Q

What is an appropriate FiO2 to use on an obese patient?

A

No less than 0.5 FiO2

73
Q

How should the provider treat intraoperative hypoxemia in an obese patient?

A

Recruitment maneuvers with PEEP (15cmH2O)

74
Q

If placing an epidural for an obese patient why is it that the provider must dose down?

A

Reduction in dose due to epidural fat and distended veins in space