Anesthesia and Obesity Flashcards
predicted body weight
similar to IBW
MALE: PWB
(KG) = 50 + (0.91 X HEIGHT IN CM – 152.4)
FEMALE: PWB
FEMALE: PWB (KG) = 45.5 + (0.91 X HEIGHT IN CM – 152.4)
1 meter=ft
3.28ft
1 meter = cm
100cm
1ft=meters
0.3meters
1in=cm
2.54cm
BMI=
weight (KG) /HT(meters)2
does BMI distinguish between overweight and overfat?
IT CANNOT DISTINGUISH BETWEEN OVERWEIGHT AND OVERFAT VERSUS HEAVILY MUSCLED AND CAN BE EASILY CLASSIFIED AS OVERWEIGHT USING BMI
does BMI take age, distribution into consideration
no, OTHER FACTORS SUCH AS AGE, FAT, CONTENT, AND DISTRIBUTION (WAIST CIRCUMFERENCE AND WAIST TO HIP RATIO)
normal BMI
18.5-24.9
underweight bmi
<18.5
overweight bmi
25-29.9
obese 1 bmi
30-34.9
obesity 2 bmi
35-39.9
morbid obesity III bmi
> /equal 40
obesity class II risk of systemic disease
increased
GYNECOID:
PERIPHERAL OBESITY: ADIPOSE TISSUE IS LOCATED PREDOMINANTLY IN THE HIPS, BUTTOCKS, AND THIGHS. THIS FAT IS LESS METABOLICALLY ACTIVE SO IT IS LESS CLOSELY ASSOCIATED WITH CVD.
VISCERAL FAT:
PARTICULAR ASSOCIATED WITH CARDIOVASCULAR DISEASE AND LVD (LEFT VENTRICLE DYSFUNCTION)
ANDROID: CENTRAL OBESITY:
ADIPOSE TISSUE IS LOCATED PREDOMINANTLY IN THE UPPER BODY (TRUNCAL DISTRIBUTION) AND IS ASSOCIATED WITH INCREASE OXYGEN CONSUMPTION AND INCREASE INCIDENCE OF CARDIOVASCULAR DISEASE
waist circumference correlate with what?
abdominal fat and is an independent risk predicator of disease
PATHOLOGY AND ANATOMIC DISTRIBUTION OF BODY FAT
BODY CIRCUMFERENCE INDICES SUCH AS WAIST CIRCUMFERENCE, WAIST-TO-HEIGHT RATIO, AND WAIST-TO-HIP RATIO HELP TO CLASSIFY THESE PATTERNS OF OBESITY (EX: ANDROID vs GYNECOID OBESITY) AND CORRELATE WITH MORTALITY AND THE RISK FOR DEVELOPING OBESITY RELATED DISEASE.
PHENTERMINE (adipex-p)
PHENTERMINE (ADIPEX-P): APPROVED FOR USE 3 MONTHS AT A TIME. CAN INDUCE TACHY PALPITATIONS, HYPERTENSION. CAN BE ADDICTIVE AND HAVE WITHDRAWAL SYMPTOMS
what needs to be considered prior to surgery with phentermine
NEEDS TO BE STOPPED PRIOR TO SURGERY. CAN HAVE SAME EFFECTS AS AN AMPHETAMINE (CARDIAC ETC. ). SEE YOUR INSTITUTION FOR HOW LONG PRIOR TO SURGERY THIS DRUG NEEDS TO BE STOPPED
when should you stop phentermine
HAVE SEEN AS LITTLE AS 48 HOURS AND AS LONG AS 3 WEEKS WHEN IT COMES TO STOPPING PHENTERMINE
PHENTERMINE AND TOPAMAX (COMBO): will show what?
PHENTERMINE AND TOPAMAX (COMBO): DRY MOUTH, PARESTHESIAS, CONSTIPATION, INSOMNIA, DIZZINESS
DECREASED LUNG COMPLIANCE
FAT ACCUMULATION ON THORAX AND ABDOMEN RESULTS IN DECREASE CHEST WALL AND LUNG COMPLIANCE
obesity have what for their respiratory system
INCREASE IN OVERALL BLOOD VOLUME AND PULMONARY BLOOD VOLUME
tell me about obesity and lung compliance and elastic resistance
INCREASED ELASTIC RESISTANCE AND DECREASE IN CHEST WALL COMPLIANCE ARE FURTHER REDUCED WHEN SUPINE RESULTING IN SHALLOW AND RAPID BREATHING AND LIMITED MAXIMUM VENTILATORY CAPACITY. RESPIRATORY MUSCLES EFFICIENCY ARE BELOW NORMAL
what is the most commonly reported abnormalities of pulmonary function in obese patients
decrease in FRC and ERV
what is the decreased FRC, VC and total lung capacity result of
reduced expiratory reserve volume
what is the relationship between FRC and closing capacity (volume at which small airways begin to close)
volume at which small airways begin to close is adversely affected
what occurs with 02 consumption and co2 even at rest
obesity increases 02 consumption and co2 production even at rest
anesthesia and supine position decreases FRC up to what percent in obesity compared to what percent in non obese patients
50% obese
20% non obese
reduced FRC
REDUCED FRC (DUE TO DECREASE ERV) CAN RESULT IN LUNG VOLUMES BELOW CLOSING CAPACITY IN THE COURSE OF NORMAL TIDAL VENTILATION, LEADING TO SMALL AIRWAY CLOSURE, VENTILATION-PERFUSION MISMATCH, RIGHT TO LEFT SHUNTING AND ARTERIAL HYPOXEMIA.
OSA is more likely to be cause by what
excessive soft tissue
PHYSIOLOGICAL ABNORMALITIES R/T OSA
HYPOXEMIA, HYPERCAPNEA
PULMONARY HPTN, SYSTEMIC VASOCONSTRICTION
SECONDARY POLYCYTHEMIA FROM RECURRENT HYPOXEMIA
INCREASED RISK OF ISCHEMIC HEART DISEASE
CEREBROVASCULAR DISEASE
RV FAILURE D/T HYPOXIC PULMONARY VASOCONSTRICTION
Gold standard diagnostic test for OSA
polysomnography (OPS)/sleep study
what can we consider pre-op for severe OSA
CPAP
what does obesity hypoventilation syndrome or pickwickian syndrome result from
long term OSA- seen in 5-10% of morbid obese
what medical conditions result from OHS, Obesity, hypoventilation
pulmonary HTN, Cor pulmonale, alteration in function and structure of the RV
where is an obese patient is the extra blood volume distributed
distributed in the fat.
what does cardiac output do with obesity
cardiac output will be increased
why does cardiac output increase and by as much as how what
increasing weight will increase as much as 20-30ml/kg of excess body fat b/c of ventricular dilation and increases in sv
increased blood volume in obese patients
non obese patient
70ml/kg
50ml/kg
what happens with increased LV wall stress
leads to hypertrophy, reduced compliance and impairment of LV filling (diastolic dysfunction) with elevated lvdp and pulmonary edema
every 10kg of weight gain increase bp sys and dia by what
3-4mmhg increase systolic
2mmhg increase diastolic
how does the renin angiotensin system play a role in obesity
increased circulating levels of antiotensinogen, aldosterone, and angiotensin- converting enzyme
5% decrease in weight leads to reduce in what?
Sifnigicant reduction in renin antiotensinogen system
Gi system and obestiy
gastric volume and acidity are increase
GI system and liver function
liver function is altered and drug metabolism is adversely affected
NPO can still have how much gastric fluid in stomach
> 25cc gastric fluid
what does regurgitation of acidic stomach contents leads to
pneumonitis
75% larger stomach volume + increased risk fo hiatal hernia, GERD, delayed gastric emptying, higher acidity, increased and pressure results in increase risk of ?
aspiration and pneumonitis
unpremediacted, non diabetic fasting obese surgical patients who are free from significant GI pathology are unlikely to have what
high volumes low PH gastric contents after routine prep fasting
obese /non obese- do they follow the same NPO guidelines
same NPO guidelines
Sevo and obese pateitns
sevo hides in the fat
when are we careful with des and obese patients
transient tachycardia
abnormalities of the liver associated with obesity include
FATTY INFILTRATION, HIGH PREVALENCE OF NONALCOHOLIC FATTY LIVER DISEASE OR NAFLD. NONALCOHOLIC STEATOHEPATITIS OR NASH, FOCAL NECROSIS, AND CIRRHOSIS.
issues with DM
wound healing, MI
25% of obese patients have which disorder
potential subclinical hypothyroidism
TSH level frequently elevated suggesting the possibility that obesity leas
to a taste of thyroid hormone resistance in peripheral tissues
type II Dm related resistance of what
peripheral adipose tissue to insulin.
regional is being used more frequently what are the advantages of it
decrease use of opioids , minimal or reduced manipulation of the airway administration of fewer meds with cardiopulmonary depression, decrease nausea and vomiting postoperatively, better post op pain control imposed post op outcomes
higher rate of block failure
technical difficulties landmarks
SIGNIFICANT KEY FACTORS IN LAW SUITS:
SUBOPTIMUM MONITORING OF PULSE OX, ETCO2 OR BOTH.
MAC- monitoring oxygen is important due to
high risk of respiratory depression
MAC use
opioids, benzo propofol cautiously and monitor co2 and sat
what is peep used for
it is the only parameter that has consistently been shown to improve respiratory function in obese subjects
further increase VT only increases the peak inspiratory airway pressure, end expiratory airway pressure and lung compliance without significantly improving arterial oxygenation
vt
what should vt be maintained at
6 - 8 mL/kg PWB TIDAL VOLUME SINCE HIGHER TIDAL VOLUMES OFFER NO ADDED ADVANTAGES DURING MECHANICAL VENTILATION OF ANESTHETIZED MORBIDLY OBESE PATIENTS
does obesity imply lung growth
no
obese patients are more likely to be exposed to higher volumes due to
miscalculations of PBW or IBW
mechanical ventilation exposed to higher airway pressures dt decreased respiratory system
compliance
why is bleeding increase in the obese patient
dt difficulty accessing surgical site larger incisions extensive dissection
AVOID RAPID INFUSION OF IVF D/T PRE-EXISTING CHF
AND THE KNOWLEDGE CHF DIAGNOSED OR UNDIAGNOSED CAN BE AN ISSUE WITH OBESE. THE USE OF IBW ESTIMATES AND APPROPRIATE MONITORING CAN HELP AVOID HYPERHYDRATION
DEXMEDETOMIDIN
ALPHA-2 AGONIST WITH SEDATION AND ANALGESIC PROPERTIES, HAS NO SIGNIFICANT ADVERSE EFFECT ON RESPIRATIONS. IT CAN REDUCE POST OP OPIOID ANALGESIC REQUIREMENTS
using peep during induction will do what
combat peri induction hypoxemia
HYPOTHYROIDISM ASSOCIATED WITH
HYPOTHYROIDISM ASSOCIATED WITH HYPOGLYCEMIA, HYPONATREMIA, AND IMPAIRED HEPATIC DRUG METABOLISM
OBESITY ASSOCIATED WITH GLOMERULAR HYPERFILTRATION .
EXCESSIVE WEIGH GAIN INCREASES RENAL TUBULAR REABSORPTION AND IMPAIRS NATRIURESIS THROUGH ACTIVATION OF THE SYMPATHETIC AND RENIN-ANGIOTENSIN SYSTEMS AS WELL AS PHYSICAL COMPRESSION
ORLISTAT (OTC ALLI RX XENICAL)
ORLISTAT (OTC ALLI RX XENICAL): BLOCKS ABSORPTION OF DIETARY FAT. IMPROVES OF BP, FASTING BLOOD SUGAR, AND LIPID PROFILES.
ORLISTAT: CHRONIC USE: FAT-SOLUBLE VITAMIN DEFICIENCY. PROLONGED PROTHROMBIN TIME WITH A NORMAL PTT MAY REFLECT VITAMIN K DEFICIENCY. SHOULD BE CORRECTED 6-24 HOURS BEFORE ELECTIVE SURGERY
be mindful of other drugs patient may be using for weight loss such as
herbs- look them up
what is the most effective treatment for morbid obesity class 3
bariatric surgery
malaabsorptive: jejunoileal bypass and biliopancreatic diversion - are these used today
rarely
restrictive vertical band- gastroplasty and adjustable gastric banding
used today
combined procedures
roux-en-y gastric bypass combines gastric restriction iwht a minimal degree of malaabsorption
less invasive technique implantable gastric stimulator
placed by lap stops peristalsis to make patient feel full has issues
most effective bariatric procedure
RYGB IS MOST EFFECTIVE BARIATRIC PROCEDURE TO PRODUCE SAFE SHORT AND LONG TERM WEIGHT LOSS IN SEVERELY OBESE PATIENTS.
what is associated with less post op pain, lower morbidity, faster recovery and less third spacing of fluid
LAP BARIATRIC SURGERY IS ASSOCIATED WITH LESS POSTOP PAIN, LOWER MORBIDITY, FASTER RECOVERY, AND LESS “THIRD-SPACING” OF FLUID
What is the only parameter that has consistently been shown to improve respiratory function in obese subjects?
PEEP
