Obesity

Question 0

How is BMI calculated?

Answer 0

weight (kg) / height (m)

Question 1

How can you calculate ideal body weight?

Answer 1

males: 105 + 6lb/in >5 feet
females: 100 + 5lb/in >5 feet

Question 2

How is obesity defined?

Answer 2

BMI >30 kg/m2

Question 3

How is overweight defined?

Answer 3

25-29 BMI, or more than 20% greater than IBW

Question 4

What are some conditions associated with obesity?

Answer 4

OSA, respiratory derangements, systemic HTN, diabetes, ischemic heart disease, CHF, delayed gastric emptying, hepatobiliary disease, thromboembolic disease, musculoskeletal disease

Question 5

What are the specific risk factors for PE?

Answer 5

truncal obesity
pre-existing vascular disease
obesity hypoventilation syndrome or OSA
BMI >60

Question 6

How do lung volumes change in obesity?

Answer 6

FRC is reduced
ERV is reduced
Tidal volumes drop to the range of closing capacity (atelectasis)

Question 7

What are the implications of a decreased FRC in an obese patient?

Answer 7

you have less time for safe apnea

Question 8

What are some respiratory changes in obesity?

Answer 8

increased O2 consumption and CO2 production
high MV
reduced chest wall compliance
restrictive lung patterns
pulmonary HTN and lung disease

Question 9

How do PFTs change with obesity?

Answer 9

PFTs will actually remain normal until the patient hits severe lung disease or pulmonary HTN

Question 10

Deviations in lung volume during position changes in the obese patient can lead to…

Answer 10

V/Q mismatch
hypoxemia
increased R to L shunt

Question 11

How does increased soft tissue around the airway in an obese patient affect the anesthesia provider?

Answer 11

harder to put them in sniffing position
obstruction of the airway
can impair the mandible and cervical mobility
difficulty maintaining mask ventilation

may consider fiberoptic intubation

Question 12

If a patient needs to be supine but can’t tolerate laying flat because of their obesity, what can you do??

Answer 12

use a wedge that elevates their chest and shoulders to about 25 degrees. this allows for better expansion of the lungs while the abdominal contents are pushed down further

Question 13

Cardiac output is increased by 0.1L/min per kilogram of extra adipose tissue. How does this effect circulating blood volume?

Answer 13

circulating blood volume will increase to perfuse the extra fat and that will place an extra strain on the myocardium, creating large LVs

Question 14

In terms of cardiac effects, obese patients have decreased reserves for…

Answer 14

hypotension
hypertension
fluid overload
tachycardia

Question 15

What are the risk factors for atherosclerosis?

Answer 15

high LDL and low HDL

Question 16

Hyperlipidemia can lead to….?

Answer 16

premature CAD
pancreatitis
premature vascular disease

Question 17

How is the severity of OSA measured?

Answer 17

number of hypopneic episodes in one hour OR

apnea hypoxic number in one hour

Question 18

What are some symptoms of OSA?

Answer 18

daytime sleepiness
snoring
oxygen desaturation
impaired concentration
morning headache

Question 19

What are the risk factors for OSA?

Answer 19

male
obese
middle age
ETOH use
drug sleep aids 
abdominal fat distribution
neck girth of >17 for men or >16 for women

Question 20

What are the effects of OSA?

Answer 20

hypoxemia
R sided heart failure
hypercapnia
pulmonary and systemic vasoconstriction
polycythemia
respiratory acidosis during sleep

Question 21

What pre-op questions should you ask a patient who is at risk for OSA?

Answer 21

sleeping patterns
snoring
daytime somnolence

Question 22

If your patient has obesity hypoventilation syndrome, what are some alternatives you can use to prevent associated symptoms?

Answer 22

observe them overnight if they were intubated

try an epidural or regional block instead of GA

Question 23

How is OHS different from OSA?

Answer 23

nocturnal central apneic events occur which means that there is apnea without a respiratory effort – patient won’t even try to take deep breaths anymore because of densitization of hypercarbia sensors in the brain

Question 24

What are the characteristics of Pickwickian syndrome/OHS?

Answer 24

obesity
hypercapnia
daytime hypersomnolence
arterial hypoxemia
pulmonary hypertension
respiratory acidosis
R sided heart failure

Question 25

What are some GI specific complications associated with obesity?

Answer 25

hiatal hernia
GERD
delayed gastric emptying
increased gastric volume and pressure 
increased gastric acidity

Question 26

What are some thromboembolic complications associated with obesity?

Answer 26

polycythemia
doubled risk of DVT
increased intra-abdominal pressure
immobility

Question 27

What are the risk factors for development of aspiration pneumonitis?

Answer 27

gastric volume >25 mL

gastric pH <2.5 associated with increased parietal cell secretion

Question 28

What are some preventive measures you can take for a patient at high risk of GI related complications?

Answer 28

order reglan and an anti-reflux drug

Question 29

What is the best predictor of difficult airway?

Answer 29

neck circumference 
(>40 in = 35% chance of difficult airway)

Question 30

What are two pre-op exams/tests all patients should have???

Answer 30

EKG and CXR

Question 31

Why is it important to ask patients about use of diet aids?

Answer 31

because if patients are on ephedrine based diet products they should have stopped taking them 2 weeks ago… cancel the case??

phen/phen can cause mitral valve problems so they may need to be cardiac cleared 1st

Question 32

What should blood sugars be before surgery?

Answer 32

400 if puts them at extreme risk for post-op infectious complications and you may have to cancel the case

Question 33

Which position provides the longest safe apnea period in an obese patient?

Answer 33

head up reverse trendelenburg

Question 34

What is the problem with placing an obese patient in the prone position?

Answer 34

increases intra-abd pressure, worsens vena cava compression and decreases FRC

**lateral position would be preferred