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Anesthesia Principles 1 > Obesity and Anesthesia > Flashcards

Obesity and Anesthesia Flashcards

1
Q

What is the 2nd leading preventable cause of death in US

A

Obesity

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2
Q

Mortality is _____ related to weight gain

A

Linearly

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3
Q

Risk of morbidity and mortality ____ with increases in BMI

A

increases

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4
Q

BMI
Calculated by:

A

Body Mass Index (adiposity normalized for height)
Kg/m^2
(Reminder 100 cm = 1 m)

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5
Q

BMI Classifications
(all of them)

A

Underweight <18.5
Normal 18.5 - 24.9
Overweight 25 - 29.9
Obese 30 - 34.9
Severely Obese 35 - 39.9
Extremely Obese >= 40
Super Obese >= 50

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6
Q

Patients with _____ or/AKA _____ obesity have increased perioperative risk + disease of HTN/DM

A

visceral or/AKA truncal

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7
Q

Ideal Body Weight (IBW)
What is it?

A

Measure of height and body mass exhibiting lowest M&M

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8
Q

How do we calculate IBW for men and women?

A

MEN: Height (cm) - 100
WOMEN: Height (cm) - 105

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9
Q

Lean Body Weight calculation

A

IBW (x) 1.3
Lean body weight is increased ~30% in obese patients to allow for increased muscle mass to carry the weight

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10
Q

____ ____ ____ is useful in drug calculation and IV dosing in morbidly obese patients

A

Ideal body weight
If administered according to actual body weight we could see toxicity, renal damage, hemodynamic instability

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11
Q

T/F: No drugs are ever given based on actual body weight

A

FALSE
Some drugs must be given according to actual weight to achieve effect

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12
Q

Obesity is associated with increased incidence of what conditions?
long list

A

Type 2 DM, coronary heart disease, HTN, HLD, cerebrovascular disease, CHF, pulmonary HTN, sleep apnea
and many many more

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13
Q

Adipose tissue is an example of a(n) _____ organ.

A

Endocrine
-reservoir of energy
-maintain heat insulation

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14
Q

Childhood obesity results from what?

A

Increased # of fat cells

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15
Q

Adult onset obesity results from what?

A

Hypertrophy of already existing fat cells

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16
Q

Apple (android) or Pear (Gynecoid) body fat distribution is associated with higher risks?

A

Apple (android)
aka visceral, central, abdominal - all the same

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17
Q

_____ is the established marker for abdominal obesity

A

Waist circumference

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18
Q

A waist circumference of > than _____ in men or _____ in women have higher risks of heart dx, DM, HTN, HLD, death.

A

MEN: >102 cm (40 in)
WOMEN: >88 cm (35 in)

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19
Q

What is the biggest anesthesia risk for our apple/android/central/abdominal (all same) body fat patients?

A

Difficult airway + intubation

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20
Q

Pear / gynecoid / peripheral (all same) body fat is associated with?

A

Varicose veins, joint disease, reduced rate of non-insulin-dependent diabetes
**LOWER risk

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21
Q

Body size is dependent on ____ and ____ factors

A

Genetic and environmental

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22
Q

Respiratory function is compromised to ____% of predicted values in obese patients

A

35%
From compression of abdomen, diaphragm, thoracic structures. Causes rapid and shallow breathing (restrictive lung dx).
*FRC, ERV, TLC, FRC all decline with increases in BMI. WILL NOT TOLERATE APNEIC PERIOD

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23
Q

Premature airway closure causes

A

Increased dead space, CO2 retention, ventilation-perfusion mismatch, shunting, hypoxemia

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24
Q

T/F: Obese patients are predisposed to respiratory failure.

A

TRUE: bolded point
Mild pulmonary or systemic insults can send these patients over the edge

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25
Q

Risk of getting OSA:
upper airway collapse leading to 10 sec breathing cessation

A

STOP BANG
>50, male, obese, fat neck, drinker or smoker, big tongue, craniofacial abnormalities

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26
Q

Risks associated from having OSA:

A

Increased CAD, HTN, CHF, CVA

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27
Q

Anesthesia risks of OSA:
USE YOUR STOP BANG PRE-OP TO BE PREPARED

A

Difficult airways, increased sensitivity to anesthesia, increased postop complications

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28
Q

OSA is officially diagnosed by:

A

Polysomnography (PSG) using an apnea-hypopnea index
AHI: 5-15 is mild
AHI: 15-30 moderate
AHI: >30 severe

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29
Q

Perioperative management of OSA:

A
  1. Use PAP - reduction in cardiovascular M&M in severe OSA patients
  2. Regional anesthesia or combined techniques to limit opioids
  3. Short acting drugs
  4. Monitoring appropriate postop
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30
Q

Obesity Hypoventilation Syndrome is characterized by:

A

aka Pickwickian Syndrome (4-20% of OSA patients)
BMI >30, OSA, awake hypercapnia, daytime hypersomnolence, arterial hypoxemia (PaO2 <70), cyanosis-induced polycythemia, respiratory acidosis, pulmonary hypertension, and right-sided heart failure

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31
Q

_____ disease is primary cause of M&M with obesity. It manifests as ____, ____, and ____.

A

CV disease
ischemic heart disease, hypertension, HF

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32
Q

CO is increased by ____ for each kg of fat acquired

A

0.1L/min
HR remains the same, so it has to be through SV increases.

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33
Q

_____ is often seen alongside HTN in obese pts and predisposes them to atherosclerosis and/or CVA.

A

Hypercholesterolemia
*HTN >2x as likely to be seen in obese pts compared to lean pts

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34
Q

____ is more common in obese individuals with central android fat distribution.

A

Ischemic Heart Disease

35
Q

Look at cardiopulmonary sequelae pic/slide

A

In summary:
-obesity (OSA/OHS) –> hypercapnia/hypoxia –> pulm HTN –> RV failure
PLUS
-Obesity –> increased CO –> increased LV workload –> LV hypertrophy –> LV failure
PLUS
-Possible HTN and/or HF
-Final result = biventricular failure

36
Q

Obese patients are at high risk of what GI issue pertinent to anesthesia?

A

Aspiration
Increased gastric residuals + reflux + increased abdominal pressure

37
Q

Obese patients are at high risk of what GI issue pertinent to anesthesia?

A

Aspiration
Increased gastric residuals + reflux + increased abdominal pressure

38
Q

NASH (aka fatty liver) is present in up to 90% of obese patients. This means what for us?

A

Altered liver function, altered drug metabolism

39
Q

What is metabolic syndrome?

A

truncal obesity, HTN, insulin resistance, dyslipidemia
-Increased CV disease and DM
-Increased postop complications

40
Q

Because of higher concentrations of _____ in bile we will commonly see obese patients for a cholecystetomy.

A

increased cholesterol concentrations

41
Q

Obese pts have higher incidence of ____ due to mechanical stress of weight bearing joints

A

osteoarthritis
-linear relationship between weight and degree of arthritis

42
Q

Pediatric obesity defined as:

A

Weight-for-height > 90th percentile
OR
BMI >/= 95th percentile specific to age and gender

43
Q

Obese adolescents have a ___-___% chance of being obese adults

A

70-80%
-higher rates of premature death/disability

44
Q

T/F: Neonatal outcomes are worse when the mom is obese as compared to normal BMI mom.

A

FALSE. There is no difference in neonatal outcomes
-mom higher risk of preeclampsia, PIH, infection, c-section, and more

45
Q

T/F: Mom is at higher risk of postpartum hemorrhage if obese.

A

FALSE. There is no increased risk of postpartum hemorrhage
-Likely a c-section (40%), difficult epidural placement, difficult airway, higher infection, higher VTE risk, larger procedural blood loss

46
Q

Non-surgical options for obese patients:

A

-Weight loss programs to lower DM/CV risks
-Lifestyle changes and education
-Drug therapy if BMI >30 or between 27-29.9 and pre-existing dx

47
Q

Pharmacotherapy options for obese patients:
2 meds

A
  1. Orlistat: lipase inhibitor
    *Check co-ags, vitamin K deficient
  2. Phentermine: sympathomimetic significant refractory hypotension with anesthesia! so we hold 7-14 days before surgery
48
Q

4 most common bariatric procedures:

A
  1. Roux-en-Y gastric bypass
    *Most common
  2. Lap adjustable gastric bypass
    *No permanent change in anatomy
  3. Lap sleeve gastrectomy
  4. Biliopancreatic diversion with duodenal switch
49
Q

____ is the gold standard for surgical obesity management.

A

Laparoscopy
-Decreased surgical times and decreased M&M

50
Q

Bariatric surgery indications:

A

-BMI >40 (>35 with medical comorbidity worse w obesity)
-Failed dietary therapy
-Psych stable
-Motivated and educated on procedure

51
Q

What tests should be considered routine before bariatric surgery?

A

EKG and blood sugar
-Due to high risk and incidence of cardiovascular dx and diabetes

52
Q

____ is considered an appropriate position for airway management in the obese pt.

A

Reverse trendelenburg
-Pt comfort, reduced reflux, easier masking, maintains FRC

53
Q

Adequate _____ is a vital step in the induction sequence in the obese population

A

Preoxygenation (full 3-5 mins with positive pressure if tolerated)
-These pts will desaturate quickly. Remember that this also effects them on extubation.

54
Q

Rather than our favorite “sniffing” position, we will have the greatest success in the _____ position in obese patients.

A

“ramped” position
-Patient should be optimally positioned for laryngoscopy PRIOR to anesthesia induction

55
Q

A LBBB is found on your preoperative EKG. What does this mean in our obese pt?

A

This is not normal, an echo is probably a good idea here

56
Q

A RBBB is found on your preoperative EKG. What does this mean in our obese pt?

A

Can be normal in our obese pt
-Symptomatic of possible right heart failure

57
Q

Due to increased HTN causing HF incidence in the obese pt, a ____ at minimum should be done preoperatively.

A

EKG, possibly echo

58
Q

T/F: All obese pts undergoing surgery should receive a prophylactic anticoagulant dose.

A

TRUE.
-Due to increased VTE risk
-Pts with BMI >50 need an increased dose

59
Q

Takeaway point
bolded info for our knowledge

A

Increased BMI = increased comorbidities = increased risk

60
Q

What are some specific anesthesia related concerns with the obese pt that we can do something about?

A

-Proper planning with appropriate tables
-Proper sized monitoring devices OR plan for invasive
-Proper positioning for likely difficult airway (Plan A/B/C)
-GI prophylaxis!!! High aspiration risk
-Extensive postoperative monitoring

61
Q

Pharmacokinetic Changes in obesity

A

INCREASES: Increased fat mass, increased CO, increased BV, increased lean body weight, increased renal clearance, increased volume of distribution for lipid-soluble drugs
DECREASES: reduced total body water, decreased pulmonary function
OTHER: changes in plasma protein binding, abnormal liver function

62
Q

Repetitive, but very preventable problem in obese with positioning specifically

A

Appropriate table size to support extra weight!!

63
Q

Water-soluble drugs are dosed according to what?

A

Ideal Body Weight, but with 30% adjustment if obese pt (Lean Body Weight)
MEN: Height (cm) - 100
WOMEN: Height (cm) - 105
LBW: IBW (x) 1.3

64
Q

Lipid-soluble drugs are dosed according to what?

A

Total Body Weight

65
Q

____ and ____ inhalation agents have shown better recovery profiles in obese patients

A

Desflurane and Sevoflurane

66
Q

T/F: Nitrous oxide cannot be used in the obese population.

A

FALSE. It is increasingly being used in extremely obese patients and may even have a analgesic effect for postoperative pain.

67
Q

If a NMB is used in the obese patient, what is crucial at the end of the procedure?

A

Full reversal and recovery
-Especially important in these patients due to their difficult airways and high postoperative complications

68
Q

The most effective pain treatment for obese patients

A

Multimodal
-Reduces complications. Limit opioids

69
Q

Propofol dosing
Induction based on:
Maintenance based on:

A

Induction: Lean body weight
Maintenance: Total body weight
-due to cardiac depression in huge doses

70
Q

Succinylcholine dosing
Intubation dose based on:

A

Total body weight
-This ensures adequate paralysis

71
Q

Rocuronium/Vecuronium/Cisatracurium dosing
All dosing based on:

A

Ideal Body Weight
-Hydrophilic drugs given according to IBW will ensure shorter duration and a more predictable recovery in this respiratory-challenged population

72
Q

Fentanyl/Sufentanil dosing
Loading dose based on:
Maintenance dose based on:

A

Loading dose: Total body weight
Maintenance: Lean body weight + response
-Elimination times correlate with degrees of obesity

73
Q

Remifentanil dosing
Infusion dose based on:

A

Ideal body weight
-Distribution volumes and elimination rates are similar to normal-sized individuals; fast offset requires planning for postoperative analgesia

74
Q

Dexmedetomidine dosing
Infusion rate

A

Constant 0.2mcg/kg per min

75
Q

Sugammadex dosing
Reversal dose based on:

A

Total body weight

76
Q

Fluid management of the obese patient:

A

-The same as with a normal weight patient
-Same for blood products also

77
Q

Ventilation Technique of obese patient:

A

-Lung protective strategy (6-8 mL/kg)

78
Q

_____ is the only parameter shown to improve respiratory function in the obese patient.

A

PEEP
-Alveolar recruitment maneuvers can be beneficial

79
Q

Waking up the obese patient:

A

-Full reversal in presence of NMB
-Extubate AWAKE with head elevated

80
Q

Your case has finished and you don’t feel great about your obese pt’s breathing. What do we do?

A

Leave em intubated

81
Q

What position is most likely going to be best for neuraxial in the obese patient?

A

Sitting upright
-Skin falls down and improves visibility of landmarks

82
Q

Issues/Concerns with neuraxial in obese pt?

A

-Catheters may migrate due to excess fat tissue
-Lack of predictability of the LA spread –> be careful with high doses due to already high risk of respiratory complications

83
Q

In a perfect world, a BMI of ____ would not be seen at an ambulatory surgery center.

A

> /= 50

Anesthesia Principles 1 (7 decks)

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