Obesity Flashcards
How is BMI calculated?
weight in kg / height in m^2
How is ideal body weight calculated?
Male = 105 + 6 for each inch over 5 ft Female = 100 + 5 for each inch over 5 ft Obesity = 20% higher
What is overweight BMI? What is obese BMI? Morbidly obese? Super-obese?
Overweight 25-29
Obese 30+
Morbid obese 40+
Super obese 50+
List some medical/surgical conditions associated with obesity
Respiratory: obstructive sleep apnea, obesity hypoventilation syndrome, restrictive lung disease
CV: HTN, cardiomegaly, CHF, ischemic heart disease, PVD, pulmonary hypertension, DVT, PE, hypercholesterolemia, sudden death
Endocrine: DM, cushing, hypothyroid
GI: hiatal/inguinal hernia, gallstones, reflux, gastric acidity, fatty liver, delayed GI emptying
Musculoskeletal: OA, back pain
Cancer (breast, prostate, cervical, uterine, colorectal)
What are the 4 big risks/conditions that are likely to lead to a thromboembolic event?
Venous stasis disease, BMI over 60, trunkal obesity, obesity hypoventilation syndrome
What are the respiratory changes with obesity?
Lung volumes are changed, FRC reduced, ERV is reduced, TV may fall into the range of closing capacity (less apnea time to intubate)
High minute ventilation, increased RR, increased O2 consumption and CO2 production, reduced chest wall compliance, restrictive lung, increased respiratory resistance
PFTs may remain normal until pulmonary hypertension develops
What respiratory changes may occur when positioning the obese patient for surgery?
Rapid de-saturation in recumbent/supine position
V/Q mismatch
Hypoxemia
Increased right to left shunt
What are cardiovascular changes in the obese population?
Cardiac output (total blood volume) is increased, cardiomegaly
Risk of hypertension, increased afterload, increased work of heart
Increased left-sided heart pressures and left ventricular hypertrophy
Increased RV workload, RV hypertrophy -> risk of biventricular failure
Risk of CAD is double -> CHF, acute MI, sudden death
Hyperlipidemia is associated with obesity, what can this lead to?
Atherosclerosis, premature CAD, premature vascular disease, pancreatitis
How is obstructive sleep apnea characterized?
Apnea >10 sec despite respiratory effort against a closed glottis
Hypopnea partial or intermittent closure/narrowing of upper airway during sleep resulting in 4% decrease in oxygen sats
Frequent episodes of apnea, oxygen desaturation, snoring, impaired concentration, morning headache
Mild 5-15 episodes an hour, moderate is 15-30, severe over 30
Obstructive sleep apnea risk factors?
Middle age, male, obesity, alcohol use, drug induced sleep aids, abdominal fat distribution, neck girth (>17 inches for men, >16 inches for women)
What can obstructive sleep apnea result in?
Hypoxemia, R heart failure, hypercapnia, pulmonary and systemic vasoconstriction, polycythemia, respiratory acidosis during sleep, arterial hypoxemia, systemic hypertension, pulmonary hypertension
Since 80% or more are undiagnosed with obstructive sleep apnea, what questions should you ask during a pre-op evaluation?
Sleeping patterns, snoring, daytime somnolence
High suspicion for obese patients
What is obesity hypoventilation syndrome/ Pickwickian syndrome?
Complication of extreme obesity, long term obstructive sleep apnea, airway difficulty with nocturnal sleep disruption,
Nocturnal central apenic events (apnea without respiratory effort) develops
Characterized by obesity, hypercapnia, daytime hyper-somnolence, arterial hypoxemia, pulmonary hypertension, respiratory acidosis, R heart failure
What gastric volumes and what pH indicates a high risk for aspiration pneumonitis?
> 25 mL
pH < 2.5 (increased parietal cell secretion)
