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Estimated __% of Americans are classified as overweight or obese. Predisposes over ___ million Americans to multiple chronic diseases and serious medical conditions
Most rapidly growing segments of obese population are.........
severely obese and superobese
Individuals with a BMI > 30, 40 and 50 kg/m2 doubled, quadrupled, and quintupled (respectively) 1986-2000.
White women 20-30 years of age with a BMI > 45 will lose __ years of life and males will lose __ years.
What is the BMI Calculation?
Weight in kilograms divided by square of height in meters (kg/m2)
What are the BMIs for normal and overweight classifications?
- Normal weight 18.5-24.9 kg/m2
- Overweight 25-29.9 kg/m2
What are the 5 grades for obesity (BMI classification)
- Grade 1 30-34.9 kg/m2
- Grade 2 35-39.9 kg/m2
- Grade 3 40-49.9 kg/m2 (severe, extreme, morbid)
- Grade 4 > 50 kg/m2 (superobese)
- Grade 5 > 60 kg/m2
What is the ideal body weight calculation?
Height (cm) – x = IBW (kg)
x = 100 for males; 105 for females
What is the calculation for lean body weight?
- Men = 50 + 2.3 x (height [in.] - 60)
- Women = 45.5 + 2.3 x (height [in.] - 60)
What is lean body weight (what does it mean)?
Total Body Weight (TBW) – adipose tissue
what is the weight we would use to calculate adjusted dosage for an obese patient?
Obese: approximately 120% IBW.
Do fat mass and LBW increase proportionally?
- Fat mass and LBW do NOT increase proportionately
As obesity increases, fat mass accounts for an increasing amount of TBW → LBW/TBW ratio decreases. What does this mean for us if we dose based on TBW?
Drug dosing based on TBW may result in overdose
Why shouldn't we just dose on ideal body weight in the obese patient?
IBW is less than actual body weight, drug dosing based on IBW may result in under dosing
What weight (IBW, LBW, or TBW) should we use when dosing medications in the morbidly obese patient?
LBW is ideal weight scalar when dosing most medications in morbidly obese patients
Most general anesthetic drugs are affected by obesity, what effect would we see?
Effects are prolonged and less predictable
What happens to the central compartment in obesity?
Nothing! Central compartment volume largely unchanged
The Vd is increased in the obese patient, what does this mean for us in terms of 1/2 life?
- Elimination half-life of lipophilic and polar drugs increased, despite increased clearance.
- Less fat-soluble drugs (some neuromuscular blockers) show little or no change in volume of distribution
What are the changes seen in plasma protein binding in the obese patient?
- Adsorption of lipophilic drugs to lipoproteins →increased free drug available.
- Plasma albumin unchanged.
- Increased α1-acid glycoprotein
Does fraction of total body water increase or decrease in the obese?
Does lean body mass increase in the obese?
YES, both increased adipose tissue & increased lean body mass. (just not proportional)
What happens to EBV and CO in the obese?
What happens to the concentration of alpha 1 acid glycoprotein?
Increased concentration free fatty acids, cholesterol, α1 acid glycoprotein.
What happens to the kidneys and drug clearance in the obese patient?
- Increased renal blood flow.
- Increased GFR.
- Increased tubular secretion.
- May have increased clearance of drugs.
- Activation of sympathetic and renin-angiotensin systems and compression of kidneys lead to increased renal tubular resorption and impaired natriuresis.
When might we see less hepatic blood flow in the obese patient?
Decreased hepatic blood flow in congestive cardiac failure
Waist circumference, waist-to-height ratio, and waist-to-hip ratio correlate with mortality and the risk for developing obesity-related diseases. Which is an independent risk factor for disease?
- Waist circumference correlates with abdominal fat.
- Independent risk predictor of disease
What should we know about Android Obesity (central obesity)?
- Truncal distribution of adipose tissue.
- Increased oxygen consumption
- Increased incidence of cardiovascular disease
- In particular, visceral fat associated with LV dysfunction
What should we know about Gynecoid Obesity (peripheral obesity)?
- Adipose distribution on hips, buttocks, thighs.
- Less metabolically active
What are the 4 respiratory co-morbidities we can see w/obesity?
- Obstructive Sleep Apnea
- Obesity Hypoventilation Syndrome
- Pulmonary Hypertension
What are the cardiac co-morbidities we can see w/obesity?
- Systemic Hypertension
- Cardiac Failure
- Sudden Cardiac Death
- Varicose Veins
What are the GI co-morbidities we can see w/obesity?
- Gallbladder Disease
- Non-alcoholic Steatohepatitis/Non-alcoholic Fatty liver disease
- Colon Cancer (increased risk for it)
What are the metabolic/endocrine co-morbidities we can see w/obesity?
- Metabolic Syndrome
- Type 2 Diabetes
- Insulin Resistance
What Heamatologic co-morbidities can we see w/obesity?
What GU/Reproductive co-morbidities can we see w/obesity?
- End-stage Renal Disease
- Preeclampsia and Eclampsia
- Prostate Cancer
- Urinary Incontinence
What are the neurologic co-morbidities we can see w/obesity?
- Pseudotumor Cerebri
- Carpal Tunnel Syndrome
What is a pseudotumor cerebri?
- intracranial pressure increases for no obvious reason.
- Symptoms mimic those of a brain tumor, but no tumor is present
- The increased intracranial pressure associated with pseudotumor cerebri can cause swelling of the optic nerve and result in vision loss.
What are the Musculoskeletal co-morbidities seen w/obesity?
- Acanthosis Nigricans (Dark pigmentation in folds of skin)
What are the psychologic things we can see w/obesity?
- Reduced Self-Esteem
- Social Stigma
What changes might we see with the respiratory system? (FRC & ERV)
- Increased demand for ventilation and breathing workload.
- Respiratory muscle inefficiency.
- Decreased FRC and ERV.
- The aforementioned often result in ventilation-perfusion mismatch, especially in the supine position.
What changes in compliance do we see with the respiratory system in obesity?
- Excess thoracic and abdominal fat decrease chest wall and lung compliance.
- Decreased total respiratory compliance in supine position due to: Increased elastic resistance & Decreased compliance of chest wall.
- Decreased pulmonary compliance leads to decreased FRC, VC and TLC.
What is the primary cause of decreased FRC in obesity?
Reduced ERV is primary cause of decreased FRC
What are the MOST COMMON abnormalities in pulmonary function?
Decreased ERV and FRC are most common abnormalities in pulmonary function
What can the decrease in FRC lead to in the obese patient?
Reduced FRC may lead to small airway closure, VQ mismatch, right-to-left shunting and ultimately, arterial hypoxemia
How much can anesthesia reduce FRC in the obese patient, compared to the non-obese?
Anesthesia reduces FRC up to 50% in obese patients compared with 20% of non-obese
What is the most sensitive indicator of the effect of obesity on pulmonary function?
What does increased workload on supportive tissues as well as metabolic activities do?
increase oxygen consumption and CO2 production
Define obstructive sleep apnea
complete cessation of airflow during breathing lasting 10 seconds or longer despite maintenance of ventilatory effort, occurring 5 or more times per hour of sleep, accompanied by a decrease of at least 4% in SaO2.
Define obstructive hypoventilation syndrome
partial reduction of airflow of greater than 50% lasting at least 10 seconds, occurring 15 or more times per hour of sleep, accompanied by a decrease of at least 4% in SaO2
How are the obstructive respiratory disorders diagnosed?
Diagnosed by polysomnography with monitoring of: EEG, ECG, EOG, ETCO2, SaO2, blood pressure, nasal or oral airflow, esophageal pressure and electromyelogram.
Obesity is the GREATEST risk factor for what respiratory problem?
Why does obesity cause OSAHS?
Increased amount of oral and pharyngeal adipose tissue (uvula, tonsils, tonsillar pillars, tongue, aryepiglottic folds and lateral pharyngeal walls).
__% of patients with OSAHS are obese.Up to __% of males and __% of females.
70; 80; 50
OSAHS plays an important role in systemic inflammation, how?
Cyclic episodes of hypoxia and reoxygenation activate the SNS → elevated levels of proinflammatory cytokines and oxidative stress of vascular endothelium → increases systemic inflammation
What are the consequences (associated co-morbidities) of OSA?
- Systemic hypertension
- Pulmonary hypertension (less common)
- Secondary polycythemia (due to hypoxemia)
- Left ventricular hypertrophy
- Cardiac arrhythmias
- Increased risk for cerebral vascular disease
What may Obesity Hypoventilation Syndrome (a.k.a. Pickwickian Syndrome) result from?
May result from long-term OSA.
What did recent studies suggest may play a role in Obesity Hypoventilation syndrome (Pickwickian Syndrome)?
Recent studies suggest leptin resistance may play a role.
Obesity Hypoventilation Syndrome (Pickwickian) is Alveolar hypoventilation independent of intrinsic lung disease. What populations is this common in?
Most common in older patients and the super obese.
What are the consequences (associated co-morbidities) of Obesity Hypoventilation Syndrome (Pickwickian)
- Hypoxemia and hypercarbia
- Pulmonary hypertension
- RV enlargement → failure
Cardiac output increases as weight increases (up to ___-__ ml/kg of excess body fat) → increased total blood volume.
20-30 ml/kg of excess body fat
Mild to moderate hypertension is seen in majority of obese patients, what does this cause?
- Causes eccentric ventricular hypertrophy.
- Left ventricular wall thickening and increased heart volume may lead to cardiac failure
Even if the obese patient is normotensive, what might increases might we see cardiovascularly?
Increased pre-load, after-load, PA pressures and elevated LV and RV stroke work are present in normotensive patients.
Increased stroke volume and ventricular dilation lead to increased left ventricular wall stress. What does this result in?
- hypertrophy, decreased compliance, and diastolic dysfunction with elevated left ventricular and diastolic pressures and pulmonary edema.
- If rate of left ventricle dilation exceeds rate of thickening, cardiomyopathy, and potentially biventricular failure occur.
Why do we see an increase in total blood volume in the obesity patient?
- Due to perfusion of excess fat.
- Result of polycythemia of chronic hypoxemia
In obesity cardiomyopathy which kind of HF is more common?
Diastolic heart failure is most common, but some exhibit systolic and diastolic dysfunction
Risk of heart failure rises steeply after___ years of severe obesity
Signs and symptoms of obesity cardiomyopathy most commonly occur in patients with a BMI > __ or body size > ___% IBW
What is the good news about the cardiomyopathy seen in obese patients?
Many of the manifestations and cardiac structure and function are reversible with substantial weight loss
What happens to the gastric volume and acidity in the obese patient?
- Increased gastric volume and acidity
- Many have volume >25 ml and pH <2.5
Why does the obese patient have delayed gastric emptying?
Delayed gastric emptying due to increased abdominal mass causing antral distention, gastrin release, and decreased pH.
A greater than 3.5 kg/m2 increase in BMI is associated with a ___-fold increase in risk for developing reflux symptoms
What are the features of Non-alcoholic Steatohepatitis/Non-alcoholic Fatty Liver Disease?
elevated liver enzymes, hepatomegaly, abnormal liver histology
What changes to the liver might we see in the obese patient?
- Fatty infiltration
- Focal necrosis
- No change in clearances of hepatically cleared drugs
There is an impaired glucose tolerance leading to type 2 diabetes. How often does this occur?
- Occurs in greater than 10% of obese patients
- Predisposed to impaired wound healing and infection
Obesity causes hyperinsulinemia which activates SNS. What will we see with this?
Increased SNS activity → sodium retention, hypertension, insulin resistance and dyslipidemia.
Subclinical hypothyroidism in approximately __% of obese patients
What are the effects of the subclinical hypothyroidism in the obese patient?
Elevated levels of TSH.May be associated with hypoglycemia, hyponatremia, and impaired hepatic drug metabolism
Metabolic syndrome affects nearly ___ million in U.S.
Who is affected more by metabolic syndrome, men or women?
Men > women
What does metabolic syndrome place the patient at increased risk for?
- Cardiovascular Disease
- Type 2 diabetes→atherosclerotic disease
- All-cause mortality
What are the features of Metabolic Syndrome?
- Proinflammatory state
- Prothrombotic state
- Endothelial dysfunction
- Polycystic ovary syndrome
- Nonalcoholic fatty liver disease
- Abdominal Obesity
- Decreased high-density lipoprotein (HDL)
- Insulin resistance with or without glucose intolerance
Clinical Criteria for Metabolic Syndrome (require at least three)
- Abdominal Obesity: Waist circumference >102 cm in men and >80 cm in women
- Elevated Fasting Glucose: >110mg/dl
- Hypertension: >130/85
- Low HDL levels: <40 mg/dl in men and <50 mg/dl in women
- Hypertriglyceridemia: >150mg/dl
Why is the obese patient more prone to blood clots?
Increased levels of fibrinogen, factors VII and VIII, von Willebrand factor, and plasminogen activator inhibitor-1
What two things are increased that increase and activate factor VII
- Increased triglycerides → increased factor VII.
- Lipemia → activates factor VII
Hyperinsulinemia induces endothelial dysfunction, what does this do to coagulation?
increases factor VIII levels and Von Willebrand factor → fibrin formation
In 1950’s Open intestinal bypass started. What was this?
- Weight loss purely by malabsorption of food.
- Bypassed all but 12-14 inches of small bowel (approximately 29 feet), the stomach left unchanged
1970’s, Open intestinal bypass us abandoned. Why?
- Serious nutritional problems.
- Liver failure.
In the 1970s, the Vertical Banded Gastroplasty (VBG) introduced by Dr Ed Mason in Iowa. What is this?
- Weight loss by restricting the intake of food in the stomach, with small bowel left unchanged.
- Stomach was reduced from approximately two quarts to one ounce using a surgical stapler.
- The gastric outlet reduced to ½ inch (one cc) with a plastic band to keep it from stretching.
- The small pouch and rigid outlet resulted in vomiting and acid reflux.
In 1970s, the vertical banded gastroplasty had what results?
- Average weight loss approximately half the patients’ excess weight.
- Long term, 50% of patients had revisions, conversions or reversals due to complications or weight loss failure
In the early 90’s: Roux en Y Gastric Bypass (RNY) developed by Dr.’s Wittgrove and Clark. What is this?
- Combined gastric restriction to limit food intake with some limited malabsorption of food in the small bowel.
- Stomach reduced to a one-ounce pouch with a narrow opening, without utilizing band for permanent restriction of the outlet, and the distal stomach and proximal small bowel were bypassed for approximately 5 feet.
Roux en Y Gastric Bypass (RNY) developed in the 1990s had what results?
- Sustained and greater weight loss compared to the VBG.
- Ultimately became the most popular weight loss surgery in the U.S.
- Averaged 75% excess weight loss.
- 90% success rate after 5 years in most studies
In 1992 the National Institutes of Health (NIH) held a consensus conference of medical experts to evaluate bariatric surgery and its role in treating morbid obesity. NIH found there were two procedures which they felt were safe and effective for treating morbid obesity, what were they??
vertical banded gastroplasty and the Roux gastric bypass
NIH set the standard to qualify for surgery, what are they?
- 100 pounds over IBW
- or BMI of 40 without health issues
- or BMI between 35- 39 with associated medical problems.
The first laparoscopic gastric bypass performed and the laparoscopic approach was quickly adopted for vertical banded gastroplasty. When was this?
Laparoscopic adjustable gastric band (initially introduced in Europe to replace the VBG) was approved for clinical trial in the U.S. when was this?
1990’s: Duodenal switch introduced by a small number of surgeons (< 5%) in the U.S, what is this?
Combined gastric and intestinal bypass procedures with both a reduction in stomach volume and a radical bypass of the small bowel, bypassing all but 3-5 feet of the 30 foot intestine.
What types of patients is the duodenal switch performed in?
Used more often in super obese patients with a BMI greater than 60, often weighing 600-800 pounds.
Why was the duodenal switch not accepted too well?
Never widely accepted by patients or surgeons due to its significant risk of malnutrition and frequent watery diarrhea
What came out of the duodenal switch by accident?
- Gastric sleeve procedure
- A group of surgeons began breaking the Duodenal Switch procedure into two separate operations performed 6 months apart in order to reduce operating time and associated risks
- The stomach size was first reduced by performing the gastric sleeve procedure resulting in about a 100-pound weight loss in 6 months.
- The second operation would bypass the small bowel and reattach the gastric sleeve to the distal small bowel to form the completed duodenal switch
Once it was found by accident, the gastric sleeve was used in patients with a BMI of what?
Surgeons began using the gastric sleeve in patients with a BMI of 40-50
Currently approximately __% of weight loss surgeries in the U.S. are gastric bypass and __% are adjustable bands or sleeve gastrectomies.
Describe the RNY surgery today
- Routes food past most of the stomach and first part of the small intestine.
- This both restricts food intake and decreases absorption of nutrients.
- Using a surgical stapler, a small stomach pouch is created.
- Small bowel is divided approximately two feet from the stomach.
- Gastrojejunostomy is created, followed by a jejunojejunostomy
Describe the Sleeve Gastrectomy today
- Restrictive procedure removing approximately 2/3 of the stomach, providing faster satiety and decreased appetite.
- Small sleeve created with a surgical stapler along inside curve of the stomach, from the pylorus to the esophagus, and the remainder of the stomach removed.
- The pyloric valve remains, allowing for the feeling of fullness.
Describe the gastric band surgery today
- A small pouch is created by placing an adjustable band at the top of the stomach to reduce it’s size.
- A small epidermal port allows for adjustment of the band to make the pouch smaller or larger.
What is the Biliopancreatic Diversion?
- Restrictive: Approximately 70% of the stomach is removed which produces both restriction of food intake and reduction of acid output.
- Malabsorption: achieved by bypassing both the duodenum and jejunum of the small intestine and taking food from the stomach directly to the distal part of the digestive tract.
- This bypass reduces the length of functioning small intestine (where most nutritional uptake occurs) so that a significant amount of fat and other macronutrients pass through, undigested.
- Greater weight loss and higher complication rate than other procedures.
What are the PROS of the RNY surgery?
- Sustained and greater weight loss with dietary compliance.
- Potential reversal of diabetes,hypertension, dyslipidemias, nonalcoholic steatohepatitis, sleep apnea and obesity-hypoventilation syndrome, cardiac dysfunction, reflux esophagitis, pseudotumor cerebri, arthritis, infertility, stress incontinence, and venous stasis ulcers.
- Decreases secretion of ghrelin.
What are the CONS of the RNY surgery?
- Malabsorption à nutritional deficiencies and anemia (secondary to malabsorption of vitamin B12).
- Decreased absorption of calcium may lead to osteoporosis and metabolic bone disease.
- Dumping syndrome
- Anastamotic leaks.
What are the PROS of the sleeve gastrectomy?
- Decreases size of stomach and decreases secretion of ghrelin.
- No malabsorption à no vitamin or mineral deficiencies.
- No anastomoses or rerouting of intestinal tract.
What are the CONS of the sleeve gastrectomy?
- Potentially slower weight loss than RNY.
- Potential for gastric leaks at staple sites.
- Limited long-term clinical data.
What are the PROS of the gastric band?
- No resection of stomach.
- No vitamin or mineral deficiency.
- No anastomoses or rerouting of intestinal tract.
- No protein-calorie malabsortption.
What are the CONS of the gastric band?
- Less weight loss.
- Routine follow-up adjustments required. For adjustments in the band
- Mechanical failure due to port or tubing leakage.
- Slippage or band erosion.
- Reflux esophagitis.
What are the Pros and Cons of Biliopancreatic Diversion?
- PRO: Greatest weight loss of all bariatric procedures.
- Cons: More technically difficult to perform
- laparoscopically. Higher rate of complications.
There are many benefits of gastric bypass surgery, a study published in (JAMA) in 2004 showed improvements in the following conditions:
- Remission of type 2 diabetes in 76.8% and significantly improved in 86% of patients.
- Elimination of hypertension in 61.7% and significantly improved in 78.5% of patients
- Sleep apnea was eliminated in 85.7% of patients.
- Joint disease, asthma and infertility dramatically improved or resolved.
- Patients lost between 62 and 75 percent of excess weight
What are the early complications of gastric bypass surgery?
- Bowel obstruction
What are the late complications of gastric bypass surgery?
- Cholelithiasis and/or cholecystitis
- Pouch dilation
- Incisional hernia
- Vitamin deficiencies
What are the contraindications to bariatric surgery?
- Persistent alcohol and drug dependence.
- Uncontrolled severe psychiatric illness.
- Cardiopulmonary disease that would make surgical risk prohibitive
Severe obesity is not associated with increased mortality but what is it associated with?
with increased length of hospital stay and greater risk of renal failure and prolonged assisted ventilation.
What two things are associated with higher rate of surgical complications (mentioned in Christine's lecture)?
BMI > 50kg/m2 and cigarette smoking associated with higher rate of surgical complications
Age greater than ___ associated with increased mortality
12-lead ECG in all patients with at least 1 risk factor for cardiac disease, poor exercise tolerance, or both. What things might we see on the EKG?
Signs of right ventricular hypertrophy (including right-axis deviation and RBBB) suggest pulmonary hypertension
Physical exam and ECG often underestimate presence and degree of cardiac pathology and dysfunction in obese patients, why is this
- Adipose tissue may obscure JVD.
- Heart sounds are often distant
Why might CV disease be masked in the obese patient?
- Obese patients are often inactive, so may have cardiovascular disease and be asymptomatic
- Young, asymptomatic patients often have some level of left ventricular dysfunction.
What kinds of things are we assessing for the presence of in our cardiac pre-op eval?
- Systemic hypertension.
- Pulmonary hypertension (fatigue, exertional dyspnea, syncope).
- Ischemic heart disease.
- Signs of LV failure.
- Signs of RV failure.
Hypertension or neck circumference > _____ may indicate OSA
Why is CPAP so great in treating OSA?
- CPAP reduces or reverses severe cardiovascular structural changes induced by severe OSA.
- Fewer perioperative complications.
- Patients on home CPAP should bring machine to hospital.
Literature suggests OSA is under-diagnosed in bariatric surgical patients, what testing has been proposed to help diagnose these patients?
- Mandatory polysomnography has been proposed but not currently part of practice guidelines.
- Unclear if PSG would improve outcomes.
What does STOP-BANG stand for?
- TIRED, fatigued, or sleepy during daytime
- OBSERVED apnea
- PRESSURE (HTN)
- BMI more than 35
- AGE over 50 years old
- NECK circumference > 15.75 inches
- GENDER (Male)
What does the STOP-BANG score tell us?
- ≥3 yes answers: High-risk for OSA
- <3 yes answers: Low-risk for OSA
What types of things might we see in the obese patient making the a difficult intubation
- Large neck circumference and high Mallampati score predictive of potential intubation difficulty.
- Excess tissue folds in mouth and pharynx.
- Limited neck mobility due to excess fat pads.
- Excess posterior cervical, suprasternal and presternal fat.
- Potential difficult mask ventilation.
Do weight and BMI correlate with a difficult intubation?
NO! Weight and BMI do NOT correlate with difficult intubation.
What pre-op meds do we give to the bariatric obese surgery patient?
- Heparin 5,000U SQ.
- Consider scopolamine patch, if not contraindicated.
- If administering anxiolytic, give supplemental oxygen and monitor pulse oximetry.
- *Do NOT over-sedate; may compromise respiratory function.
What two drugs should we base on TBW?
- Propofol (maintenance dose)
What 4 drugs should we base on LBW?
- Propofol (induction dose)
What 4 drugs should we base on IBW?
- Vecuronium, Rocuronium
What should we remember when reversing MR in the obese patient?
MR tend to last longer, could be weaker or not reversal in the end, 1 weak twitch and reverse, they usually don’t fly.
What is Precedex?
- Alpha-2 agonist
- Sedative, analgesic, sympatholytic and anxiolytic effects
Why do we like Precedex in the bariatric obese surgery patient?
Reduces requirement for volatile anesthetics, sedatives and analgesics without causing significant respiratory depression
What are the side effects to Precedex?
- sinus arrest
- transient hypertension.
What is the dosing of Precedex?
- Dose approximately 120% of IBW.
- Loading dose – 1 mcg/kg over 10-20 minutes then, 0.2-0.7mcg/kg/hr
- Majority is 0.5mcg/kg/hr for the case. About 20-30min before case is finished go to 0.2 then wake them up on that then turn it off.
What is clonidine and when do we give it?
- Alpha-2 agonist
- Preoperative oral clonidine reduces anesthetic and opioid requirements
What should we do for positioning the obese patient?
- Reverse Trendelenberg (30-45 degrees). Reverse Trendelenburg has been shown to be better than back up to increase FRC.
- May need “Troop Pillow” or ramp for optimal laryngoscopy.
- Pad and protect pressure areas.
- Carpal tunnel syndrome, brachial plexus and lower extremity nerve injuries common.
Adequate preoxygenation a must! What can help pre-oxygenate?
Consider CPAP 10 cm H2O during preoxygenation.
When should we start the Precedex?
If using dexmedatomidine, may begin bolus after monitors applied. (start prior to induction)
Where should we measure the BP in the obese patient?
Study found no difference in measurement b/w upper arm and forearm for placement of BP cuff.
What anesthetic agents should we use for maintenence in the bariatric obese surgery patient?
- May use TIVA with propofol and remifentanil.
- If using Precedex; 0.5-0.7 mcg/kg/hr and decrease to 0.2 mcg/kg/hr prior to end of procedure.
- Desflurane: Randomized trials show immediate and intermediate recoveries are more rapid and consistent and have higher oxygen saturation post-operatively.
How can we help maintain FRC and improve oxygenation during the maintenance phase?
PEEP 15cm H2O has been shown to maintain FRC and improve oxygenation.
What is our goal fluid status for the bariatric surgery patient?
- Maintain euvolemia and normothermia
- 3-4L of fluid. 3L now because no Foley. Reason is to decrease the risk of DVT.
- Downside of using a lot of fluid is their respiratory status.
- Also bowel edema can be caused. So don’t want excess IVF.
What position is the patient in most of the time for bariatric surgery?
What should we know about the OGT for the Roux-en-Y?
- Place OGT after induction to decompress stomach, and remove prior to stapling for gastric pouch.
- Leak test to check integrity of anastomosis.
- Place OGT, clamp vent, insufflate with 2L oxygen.
What should we know about the OGT in the Sleeve gastrectomy?
- Place OGT after induction to decompress stomach and remove prior to creation of sleeve.
- Place bougie (size determined by surgeon) and manipulate position at surgeon’s direction for the sizing and stapling of the stomach.
What do we do for emergence of the bariatric surgery patient?
- Reverse trendelenberg position. (increases FRC)
- CPAP during spontaneous ventilation may increase vital capacity and oxygenation.
- Fully awake (& fullly reversed) prior to extubation.
- Consider titrating small doses of dilaudid or morphine (use sparingly) if respiratory effort and LOC adequate.
- Discontinue Precedex after extubation.
- Supplemental O2 and HOB elevated for transport.
What is the primary issue for post-op care of the bariatric surgery patient?
Primary issue is underlying sleep apnea complicated by anesthetic agents and need for postoperative pain management
How can we reduce atelectasis and prevent hypoxemia in the bariatric surgery patient?
- Early use of CPAP or BiPAP may reduce atelectasis and prevent hypoxemia.
- Incidence of anastomotic leak is not increased.
How long are bariatric surgery patients in the PACU?
PACU for 3 hours.
What monitoring must be done until the bariatric surgery patient goes home?
Continuous pulse oximetry until d/c from hospital.
What pain analgesics do we give post-op
- Pain control typically managed with PCA, without continuous infusion.
- If open procedure, opioid-free epidural for patients with OSA.
- No NSAIDS for 24 hours if intestinal anastamosis.
For closed claims, obesity was a factor in what two types of events?
- Induction, 37%
- Extubation, 67% (28% had OSA)
In closed claims, __% of adverse respiratory events secondary to opioid administration occurred in obese patients
Need to remove excess skin in a surgery after weight loss, what should we keep in mind for this type of procedure?
- Come into OR and it’s humiliating experience for them, standing in the OR, prepping front and back and then lie down on sterile drape on OR table.
- KEEP room warm and try to keep pt comfortable.
- Skin removed, which is vascular so blood loss. lots of fluid shifts, difficult to keep warm.
- Sterile body warmers that you can place under them.