Obese Population Flashcards by Allison Sass

Overweight vs. Obesity

Overweight - increased body weight above standard r/t height BMI 25-30kg/m^2
Obesity - excessive body weight based on patient age, gender, & height (body weight >20% IBW) energy imbalance disorder >30kg/m^2

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Ideal Body Weight

Height (cm)
Weight (in) x 2.5 = cm
Male - 100
Female - 105

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Adjusted Body Weight

ABW

0.4 (TBW - IBW) + IBW

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Lean Body Mass

LBM

IBW + 20%

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Body Mass Index

BMI
Weight (kg) / Height m^2

BMI > 30kg/m^2 (obesity) associated w/ ↑morbidity r/t stroke, ischemic heart disease, HTN, & diabetes

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Obesity Classes

1 BMI 30-35
2 BMI 35-40
3 BMI 40-50
Superobese BMI >50

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Android Obesity

Abdominal (central) obesity
More common in men
Higher incidence metabolic disturbances
↑risk ischemic heart disease, stroke, diabetes, death

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Gynecoid Obesity

Gynecoid fat distribution
Fat around hips & buttocks
More common in females

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Disease Processes Associated w/ Obesity

OSA or hypoventilation syndrome
Restrictive lung disease
HTN/CAD
Hyperlipidemia
GERD or delayed gastric emptying
T2D
Gallbladder disease
Cirrhosis/fatty liver disease
Venous stasis or thromboembolic disease
Degenerative joint/disc disease
↑breast, prostate, cervical, uterine, & colorectal cancer
Psychological & socioeconomic effects

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Pulmonary Alternations

↓chest wall & lung compliance d/t fat accumulation
Breathe at low lung volumes
Thoracic kyphosis/lumbar lordosis
↓FRC/VC/IC/TLC/ERV
Closing volume close to or w/in tidal breathing
↑metabolic demand, WOB, small airway closures V/Q mismatch → hypoxemia
↑pulmonary blood volume
↑oxygen consumption & CO2 production
High minute ventilation ↑WOB
→ lung disease & pulmonary HTN

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OSA Types

Obstructive
Central
Obesity hypoventilation syndrome (Pickwickian)

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Obstructive Sleep Apnea

Cessation airflow but maintain respiratory effort

Abnormal relaxation genioglossus & pharyngeal muscles pull tongue forward

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Central Sleep Apnea

Cessation both airflow & respiratory efforts

Problem in medullary ventilatory center

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Obesity Hypoventilation Syndrome

Pickwickian syndrome
Most severe OSA leading to cor pulmonale (R sided heart failure) r/t morbid obesity
Extreme obesity complication
Long-term OSA
Hypercapnia PCO2 >45mmHg, hypoxia (HPV), cyanosis induced polycythemia, somnolence & eventual R sided heart failure, pulmonary HTN
Nocturnal sleep disruption & central apneic events
Desensitized to CO2
Airway difficulty

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Polysomnography

OSA diagnosis
Apnea >10sec cessation airflow despite respiratory effort against closed glottis
Hypopnea 50% reduction size or number breaths lasts at least 10sec compared to normal
Apnea-hypopnea index (# per hour)
>30 severe
16-30 moderate
<15 mild

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Uvulopalatopharyngoplasty

UPPP
OSA corrective procedure
Enlarges airway
Remove tonsils, part soft palate, & uvula

Diathermy Palatoplasty

Heat tissue producing scar tightens in 6-8wks

Obesity Airway Changes

TMJ & atlanto-axial joint & cervical spine movement limited d/t upper thoracic & low cervical fat pads
Redundant tissue folds in mouth & pharynx = narrowed upper airway
Short, thick neck
Measure neck circumference
Shortened distance b/w mandible & sternal fat pads
Difficult to maintain mask airway

Cardiovascular Alterations

↑total blood volume
↑CO (expanded blood volume puts strain on myocardium)
↑RAAS & SNS activity → HTN
CAD risk present w/ angina, CHF, acute MI, & sudden death
↑L sided heart pressures & L ventricular pressures
EKG L or R ventricular hypertrophy, ischemia, & conduction defects
↑L ventricular wall stress → hypertrophy ↓compliance, impaired L ventricle filling ↑LVEDP → pulmonary edema
Obesity cardiomyopathy

Hematologic Alterations

Polycythemia & hypercoagulation
Thromboembolic risk
- DVT risk double
- ↑blood viscosity
- ↑intra-abdominal pressure
- Immobility → venous stasis

Gastrointestinal Alterations

↑incidence hiatal hernia, GERD, gallbladder disease

Risk aspiration pneumonitis

Hepatic Alterations

Fatty liver infiltration - inflammation, cirrhosis, & focal necrosis
High prevalence nonalcoholic fatty liver disease
Abnormal LFTs

Renal Alterations

↑renal plasma flow & GFR

↑renal tubular reabsorption & impaired natriuresis 2° SNS & RAAS activation

Endocrine Alterations

Secrete more insulin but resistant to insulin effects
Develop non-insulin dependent T2D
Metabolic syndrome
- Central obesity
- ↑triglyceride levels
- ↓HDL
- Glucose intolerance
- HTN

Musculoskeletal Alterations

``` Osteoarthritis Degenerative joint disease Mechanical load weight-bearing joints Inflammatory response Back pain Stress fractures (bone demineralization) ```

CNS Alterations

ANS dysfunction Peripheral neuropathies Stroke Idiopathic intracranial HTN

Hyperlipidemia

↑LDL ↓HDL cholesterol r/t atherosclerosis CAD Vascular disease Pancreatitis

Pharmacokinetic Alterations

↑blood volume & CO ↓total body water ↑adipose & lean tissue Variable alterations in protein binding Organomegaly Hepatic clearance unchanged despite histological & LFT alterations ↑renal drug clearance (GFR, renal blood flow, tubular secretion) Lipophilic drugs ↑elimination 1/2 life ↑Vd w/ normal clearance

Preop Considerations

↑HTN incidence Pulmonary HTN = dyspnea, fatigue, syncope, tricuspid regurgitation, R ventricular hypertrophy, R axis deviation, prominent PA on CXR R/L sided ventricular failure CAD/ischemic heart disease Excess adipose tissue Assess peripheral & central venous access Thromboprophylaxis

General Anesthesia

↑Succinylcholine dose Desflurane ↓blood:gas coefficient Avoid N2O d/t oxygen demands Short-acting opioids to minimize respiratory depression Dexmedetomidine - no adverse effects on respiration↑

Mechanical Ventilation

``` PEEP improves FRC & arterial oxygenation Monitor BP Recruitment maneuvers to improve oxygenation Pressure-controlled ventilation Manipulate I:E ratio ```

Fluid Management

Calculate based on lean or IBW | ↑blood loss

Emergence

``` Respiratory failure = 1° problem Extubate fully awake after NMB reversed Ensure adequate mechanical ventilation Change position to semi-upright HOB >30° Wean pressure-support ventilation w/ PEEP 100% FiO2 Place NP airway ``` Postop CPAP or BiPAP Mechanical ventilation Respiratory monitoring

Postop Analgesia

Opioid-induced ventilatory depression Multimodal approach to postop pain control Peripheral nerve block w/ continuous LA infusion w/ or w/o small opioid doses Local wound infiltration Opioids based on IBW