obesity Flashcards
how many calories are required to produce 1g of body fat
9 calories
1g of carbs provides how many calories
4 calories
1g of protein provides how many calories
4 calories
1st and second leading causes of preventable death
1st smoking
2nd obesity
android obesity overview
most common in men and metabolically active
characterized by central visceral or abdominal fat accumulation
waist size >40 inches for men and >35 inches for women
associated with increased risk of ischemic heart disease, HTN, dyslipidemia, insulin resistance, death
gynecoid obesity overview
more common in women, characterized by gluteal and femoral fat accumulation
metabolically inactive, primarily used for energy storage
more likely to develop joint disease and varicose veins
reduced incidence of non insulin dependent DM
metabolic syndrome has at least 3 of the following
fasting plasma glucose >110mg/dL
abdominal obesity (>40 inches in men and >35 in women)
serum triglycerides >150mg/dL
HDL <40mg/dL in men and <50mg/dL in women
BP >135/85mmHg
BMI=
weight (kg) / height (m^2)
weight conversion is 2.2
height conversion to cm first (2.54) then to meters (cm / 100)
BMI = kg/m^2
adult BMI classification
child body weight class (2-18y)
IBW calculation (men v women)
men: height (cm) - 100
women: height (cm) - 105
respiratory effects of obesity
produces a restrictive ventilatory effect
reduction in FRC (due to decrease in ERV)
decreased VC, TLC
lung inflation in an obese patient is inhibited because
chest fat compresses rib cage and hinders outward expansion
abdominal fat shifts diaphragm cephalic and compresses the lungs
kyphosis and lordosis develop over time, which alters geometry of ribcage
how does PaCO2 differ in obese patient
patient may have hypoxemia but PaCO2 is usually normal r/t high diffusing capacity of CO2
because fat is metabolically active, what increases
O2 consumption, CO2 production, MV
HELP position
head elevated laryngoscopy position
-idea is to elevate head, shoulders, and upper body above the chest
-horizontal line from sternal notch to external auditory meatus
how to pre oxygenate obese patient
100% FiO2 + CPAP 10cmH2O until end tidal is >90%. this prolongs time before desaturation occurs by 50%
when does postoperative hypoxemia happen in this population
immediately or 2-5d postop
strategies to maximize postop oxygenation include
CPAP or BiPAP after extubation (esp if patient uses it at home)
elevate HOB 30 degrees
early ambulation
control surgical pain (non opioid analgesics and regional)
incentive spirometry
BV and CO
HR is usually unchanged but SV increases. CO increases an extra 100mL/min for every extra kg of fat
common EKG changes and causes
low voltage EKG (increased distance between heart and leads)
left axis deviation (stomach pushes heart up and to left, LVH secondary to volume overload and HTN)
right axis deviation (RV hypertrophy from OSA and volume overload)
QT prolongation (increases the risk of sudden death
ischemia (O2 supply and demand mismatch)
dysrhythmias (caused by fatty infiltration of conduction system, myocardial hypertrophy, hypoxemia, hypercarbia, obesity hypoventilation syndrome, ischemic heart disease
most useful confirmation of pHTN
presence of tricuspid regurg on TEE
what happens to Vd of lipophilic drugs? hydrophilic?
lipophilic: increased d/t larger fat mass
hydrophilic: increased d/t larger muscle mass and BV
circulation time in obese population
shortened circulation time due too larger CO
Vd of drugs in obese patient is altered by
increased BV
increased CO
altered plasma protein binding
lipid solubility of the drug
does muscle mass increase?
fat mass AND muscle mass increases
lean body weight (LBW) =
IBW x 1.3
propofol
induction dose should be based on
maintenance dose should be based on
induction dose should be based on LBW (IBW x 1.3)
maintenance dose should be based on TBW
succ intubation dose should be based on
TBW
rocuronium intubation dose should be based n
LBW
vec maintenance dose should be based on
LBW
cis intubation dose should be based on
TBW
fent loading dose should be based on
TBW
sufent maintenance dose should be based on
LBW
remifent loading nad maintenance dose should be based on
LBW
midaz loading and maintenance dose should be based on
TBW (not preop anxiolysis though)
r/t increased central Vd
how much of normal epidural dose to give
75%
three sets of muscles that dilate upper aw
tensor palatine (opens nasopharynx)
geniglossus (opens oropharynx)
hyoid muscle (opens hypo pharynx)
OSA
defined as cessation of air flow for at least 10 seconds
with 5 or more unsuccessful efforts to breathe and a >4% reduction in SaO2
hypopnea
common phenomenon in OSA. 50% reduction in air flow for 15 seconds, 15 or more times per hour, and is linked to snoring and decreased O2 saturation
things that increase the likelihood that a patient has OSA
BMI >30kg/m^2
abdominal fat distribution
large neck girth (>17inches for men and >16 inches for women)
pathophysiology of OSA
apnea/hypopnea index
categorizes severity of OSA
mild: 5-15 episodes/h
moderate: 15-30 episodes/h
severe: >30 episodes/h
classic triad of dysfunctional sleep
- apnea or snoring with hypopnea during sleep
- arousal from sleep
- daytime somnolence
definitive test for OSA and AHI (apnea hypopnea index) equation
polysonmography, AHI= number of episodes of apnea and hypopnea/hours of sleep
STOPBANG and high risk v low risk for OSA
high risk >3 q answered yes
low risk < 3 q answered yes
obesity hypoventilation syndrome
long term consequence of OSA. over time, resp center in medulla fails to adequately respond to hypercarbia
classic presentation: apnea during sleep WITHOUT resp effort
old school name is pickwickian syndrome
dx criteria for obesity hypoventilation syndrome
BMI >30
awake PaCO2 >45mmHg
dysfunctional breathing during sleep
signs of obesity hypoventilation syndrome
obesity
hyper somnolence during the day
hypoxemia
hypercarbia
resp acidosis
compensatory metabolic alkalosis
polycythemia
pHTN
right HF
type of weight loss procedure: malapsorption
examples
key points
type of weight loss procedure: restriction
examples
key points
type of weight loss procedure: combination
examples
key points
most common s/sx of anastomotic leak include
- tachycardia
- fever
- abdominal pain
Ma Huang
appetite suppressant, natural source of ephedrine. complications of adrenergic overstimulation including HTN, CVA, sz, death
phentermine
NE reuptake inhibitor that acts as appetite suppressant and increases BMR
sibutramine
NE and serotonin reuptake inhibitor, suppresses appetite and increases BMR
risks include adrenergic overstimulation and serotonin syndrome
orlistat
lipase inhibitor that reversibly binds to lipase and hinders absorption and digestion of consumed fats. have to supplement ADEK vitamins
for a patient undergoing laparoscopic gastric bypass, fluids should be based on
lean body weight
