Anesthesia implications for obesity Flashcards
Factors that influence obesity
Influenced by;
metabolic factors,
hormones,
neural regulation and
pathologic syndromes in addition to behavioral, cultural, and
socioeconomic factors
BMI equation
Patient weight (kg)/ height2 in meters = kg/m2
created by insurance companies to calculate risk
What does BMI not differentiate between
Overweight and overfat
Waist circumference, waist-hip ration, age
Android fat distribution
“central” obesity
Upper body (truncal)
Associated with ↑ oxygen consumption/cardiovascular dz
Gynecoid Fat distribution
“peripheral” obesity
Hips, buttocks, thighs
Less metabolically active
Not really associated with CV disease (genetics)
Total blood volume ____ in obesity
increases
On a volume-to-weight ratio is lower 50ml/kg
Most distributed to adipose tissue
CO is ____ in obesity because of ______
increased
d/t LV dilation and ↑ stroke volume
20-30ml/kg of excess body fat
Increase in cardiac dysrhythmias is due to____
d/t fatty infiltrates of conduction system, CAD,
EKG changes with obesity
Low QRS voltage; because of increased impedence,
LVH,
left axis
Hematologic changes with obesity
↑er levels of fibrinogen, factor VII, VIII, von Willebrand —-> Hypercoagulability
Endothelial dysfunction in obesity is due to_____
higher levels of factor VIII and von Willebrand
Gastric considerations for obesity
Gastric volume and acidity are increased -> Intragastric pressure increases -> Relaxation of LES and hiatal hernia formation (increased)
Delayed gastric emptying
Gastric levels and ph for risk of pneumonititis
Volume > 25 ml and pH < 2.5…levels for aspiration pneumonitis
Hepatic changes with obesity
Hepatic function/drug metabolism is altered
decreased albumin in circulation
RBF _____ with obesity
increases (Glomerular hyperfiltration)
will then have a drop off as the kidneys dont perfuse as well
Increased renal tubular reabsorption results in what? (2)
Impairs natriuresis
Activates renin-angiotensin system
Increased level of SNS activity in obesity results in what? (4)
Insulin resistance…impaired glucose metabolism
Enhanced pressor activity of norepi and angiotensin II
Sodium retention
Thyroid hormone resistance
Hypothyroidism prevalence in obesity
Hypothyroidism in 25% of morbidly obese patients
Metabolic syndrome (8)
*Abdominal obesity; (Uses waist circumference (not BMI))
*Decreases levels of HDL
*Hypertriglyceridemia
Hyperinsulinemia
*Glucose intolerance
*Hypertension
Proinflammatory state
Prothrombotic state
- at least 3 must be present for diagnosis
Risk factors for metabolic syndrome (3)
Increased age
Men > women
Hispanics and South Asians
Metabolic syndrome may result from ____, ____,_____,____
May result from chronic corticosteroids, antidepressants, antipsychotics, protease inhibitors
Metabolic syndrome results in increased risk of ________ (5)
Cardiovascular disease
Type 2 diabetes mellitus
Polycystic ovary syndrome
Nonalcoholic fatty liver disease
Improper immune responses
OSA dx (4)
Complete cessation of breathing
Lasting 10 seconds or >
5x or > each hour of sleep
Decreased sat 4%
Hypopnea dx (4)
Reduction in airflow 50% or >
Lasting 10 seconds or >
15 x or more/hour of sleep
Decreased sat 4%
name for Sleep study
polysomnography
apnea/hypopnea index (AHI)= total # of events/total sleep time
ranking for mild, moderate, severe
Mild: 5-15/hr
Moderate: 15-30/hr
Severe: > 30/hr
Treatment (CPAP, weight loss) required for mod/severe disease OSA d/t risk of (4)
Systemic/Pulmonary hypertension
LVH
Cardiac dysrhythmias
Cognitive impairment
Obesity hypoventilation syndrome other name
Pickwickian syndrome
Obesity hypoventilation syndrome results from _____
Results from long-term OSA…5-10% of morbidly obese
Obesity hypoventilation syndrome results in______(2)
Pulmonary hypertension
Cor pulmonale
Dx of Obesity hypoventilation syndrome (2)
BMI > 30 kg/m2
Awake hypercapnia
Phentermine factors (4)
Sympathomimetic which ↓ appetite
FDA approved for only 3 months
Tachycardia, palpitations, hypertension, dependence, abuse
No longer in combo with Fenfluramine (caused valvular disorders)
Orlistat factors (4)
Blocks absorption of dietary fat
Liquid stool, oily spotting, fecal urgency, flatulence, abdominal cramps
Fat soluble vitamin deficiencies with chronic use
Possible Vit K deficiency…prolonged PT
when to stop taking Phentermine and what are the side effects if not
tachycardia and hypotension
stay off for 2 weeks
OTC Herbals on obesity factors (4)
Pancreatic lipase inhibitors…caffeine, green tea
Appetite suppressors…ginseng, ephedra, sunflower oil
Energy stimulants…acai berry
Regulate lipid metabolism…soybean, fish oil, oolong tea
GLP-1 Agonists
Results in delayed gastric emptying
Glucagon-like Peptide-1 Receptor Agonists for Adults names
Dulaglutide
Exenatide (IR)
Liraglutide(1.2 mg1.8mg)
Semaglutide
Semaglutide
Trulicity
Dulaglutide
Byetta
Exenatide (IR)
Victoza
Liraglutide
Ozempic, Wegovy
Semaglutide
Rybelsus
Semaglutide
When to hold GLP1-agonists
For patients on daily dosing consider holding GLP-1 agonists on the day of the procedure/surgery. For patients on weekly dosing consider holding GLP-1 agonists a week prior to the procedure/surgery
If GLP1 - agonists are presceibed for dm management are held ______
If GLP-1 agonists prescribed for diabetes management are held for longer than the dosing schedule, consider consulting an endocrinologist for bridging the antidiabetic therapy to avoid hyperglycemia.
If pt shows up day of with these symptoms you should delay the case
severe nausea/vomiting/retching, abdominal bloating, or abdominal pain are present
If the patient has no GI symptoms, but the GLP-1 agonists were not held as advised_____
rsi for full stomach
US to eval gastric volume
Gastric volume scanning with obese pts
depth of 7 instead of 3 cm
CSA of gastric antrum may be bigger but still 1.5 ml/kg (useIBW)
Preoperative evaluation focuses on evidence of ______ (4)
-Hypertension
-Diabetes
-Heart failure
-Hypoventilation syndrome
If they use cpap ________ suggest difficult mask ventilation
CPAP usage of > 10cm H2O suggests difficult mask ventilation
consider doing awake intubation
Surgical history with obesity to consider
-Compare past/current weight
-Ease/difficult intubations
-Intravenous access
-Need for ICU admission
-Surgical outcomes
Medications to dc with obese pts
antihypertensives,
insulin,
oral hypoglycemics
Respiratory volumes changes with obesity
⬇️ vital capacity
⬇️ inspiratory capacity
⬇️ expiratory reserve volume
⬇️ functional residual capacity
Low compliance
Closing capacity is close to or within tidal breathing (especially when supine/recumbent)
Supine considerations for obesity
Ventilatory impairment
Compression of IVC and Ao
Reports of rhabdomyolysis on gluteal muscles
(Leads to renal failure/death)
Prone considerations for obesity
Cushioning pads may have excessive pressure
Skin breakdown, tissue necrosis/infections
Lateral decubitus considerations with obesity
Dependent hip pressure ulcers
Impossible or unnecessary to place axillary rolls
Favored over prone
Lithotomy considerations with obesity
Regular stirrups may not support weight
Tissue compression/compartment syndrome
Airway assessment in obesity can have increased adipose depositing into ______ (6)
Uvula
Tonsils
Tonsillar pillars
Tongue
Aryepiglottic folds
Lateral pharyngeal walls
The oropharynx can change into an _____ in obestiy
Changes oropharynx into an ellipse
Short transverse/long AP axis
Inverse relationship between degree of obesity and_______ area
pharyngeal
Predictors of difficult intubation (4)
Small mouth opening
Large/protuberant teeth
Limited neck mobility
Retrognathia
BMI not necessarily an independent predictor
Desaturation to 90% with Normal vs obese
Normal BMI: 6 minutes
Morbidly obese BMI: less than 3 minutes
In an effort to prevent atelectasis and desaturation you should _______
CPAP during preoxygenation… 10cm (close apl)
Positioning 25-30 degrees head up for obese patients.30 degrees reverse Trendelenburg even better
Recruitment maneuvers then PEEP 10cm
Mechanical ventilation after induction
Aspiration Prophylaxis with identifiable risk factors in Obesity (4)
Histamine receptor agonists
Proton pump inhibitors
RSI
Awake fiberoptic intubation
Advantages of regional anesthesia in obesity
Less airway manipulation
Fewer cardiopulmonary depressants
↓ chance of PONV
Better postop pain control (at least initially)
Technical difficulties with regional anesthesia in obesity
Longer needles
Different ultrasound probes
Smaller doses (epidurals) d/t smaller space…cephalad spread
Higher rates of block failure
Higher rates of hypotension after block d/t IVC/Ao compression
BP falsely ____ if cuff is too small
elevated
Bp cuff bladder should circle at least ____ of circumference
75%
Opioids, Propofol, Benzodiazepines on obese pts
Exaggerated responses (especially in pts with OSA)
Decrease pharyngeal musculature
Decreased airway patency
Meds favored for OSA
Short acting…remi/fentanyl most favored
α2 agonists…dexmedetomidine
Volatiles on obesity
Diminish ventilatory response to CO2
Nitrous not favored d/t high oxygen demand in pts
Drugs based on IBW
Propofol
Vecuronium
Rocuronium
Remifentanil
Drugs based on TBW (hydrohilic)
Midazolam
Succinylcholine
Cisatracurium
Fentanyl
Sufentail
Drug dosing is based on _____ of the drug
lipid solubility
Favored volatile for Obesity
Based on tissue solubility
Desflurane probably favored
Obese are more likely to becomes what temperature?
hypothermic (larger body habitus exposed)
Postoperative management for obese pts
-sit up
-fully reverse nmB
-Pressure support mode during emergence
-Continue home levels of CPAP
-Non-opioid or opioid sparing
-Consider when/where cases are done
non opioid analgesia for obese pts
Tramadol, dexmedetomidine, ketamine, clonidine
