Flashcards in Obesity Deck (35)
How can you calculate ideal body weight?
males: 105 + 6lb/in >5 feet
females: 100 + 5lb/in >5 feet
How is BMI calculated?
weight (kg) / height (m)
How is obesity defined?
BMI >30 kg/m2
How is overweight defined?
25-29 BMI, or more than 20% greater than IBW
What are some conditions associated with obesity?
OSA, respiratory derangements, systemic HTN, diabetes, ischemic heart disease, CHF, delayed gastric emptying, hepatobiliary disease, thromboembolic disease, musculoskeletal disease
What are the specific risk factors for PE?
pre-existing vascular disease
obesity hypoventilation syndrome or OSA
How do lung volumes change in obesity?
FRC is reduced
ERV is reduced
Tidal volumes drop to the range of closing capacity (atelectasis)
What are the implications of a decreased FRC in an obese patient?
you have less time for safe apnea
What are some respiratory changes in obesity?
increased O2 consumption and CO2 production
reduced chest wall compliance
restrictive lung patterns
pulmonary HTN and lung disease
How do PFTs change with obesity?
PFTs will actually remain normal until the patient hits severe lung disease or pulmonary HTN
Deviations in lung volume during position changes in the obese patient can lead to...
increased R to L shunt
How does increased soft tissue around the airway in an obese patient affect the anesthesia provider?
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
If a patient needs to be supine but can't tolerate laying flat because of their obesity, what can you do??
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
Cardiac output is increased by 0.1L/min per kilogram of extra adipose tissue. How does this effect circulating blood volume?
circulating blood volume will increase to perfuse the extra fat and that will place an extra strain on the myocardium, creating large LVs
In terms of cardiac effects, obese patients have decreased reserves for...
What are the risk factors for atherosclerosis?
high LDL and low HDL
Hyperlipidemia can lead to....?
premature vascular disease
How is the severity of OSA measured?
number of hypopneic episodes in one hour OR
apnea hypoxic number in one hour
What are some symptoms of OSA?
What are the risk factors for OSA?
drug sleep aids
abdominal fat distribution
neck girth of >17 for men or >16 for women
What are the effects of OSA?
R sided heart failure
pulmonary and systemic vasoconstriction
respiratory acidosis during sleep
What pre-op questions should you ask a patient who is at risk for OSA?
If your patient has obesity hypoventilation syndrome, what are some alternatives you can use to prevent associated symptoms?
observe them overnight if they were intubated
try an epidural or regional block instead of GA
How is OHS different from OSA?
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
What are the characteristics of Pickwickian syndrome/OHS?
R sided heart failure
What are some GI specific complications associated with obesity?
delayed gastric emptying
increased gastric volume and pressure
increased gastric acidity
What are some thromboembolic complications associated with obesity?
doubled risk of DVT
increased intra-abdominal pressure
What are the risk factors for development of aspiration pneumonitis?
gastric volume >25 mL
gastric pH <2.5 associated with increased parietal cell secretion
What are some preventive measures you can take for a patient at high risk of GI related complications?
order reglan and an anti-reflux drug