Preoperative Evaluation of the Bariatric Surgery Patient

Eric I. Rosenberg, MD, MSPH, FACP

Case #1“. . . evaluate for metabolic disorder”

“Super Super” Morbid Obesity• 53 year-old woman

• 399 lbs, 4’ 10”, BMI 83.3

• Bariatric surgeon notes central obesity, abdominal bruises, buffalo hump

HistoryPMHx: Catatonic schizophrenia

Bipolar Disorder

PGynHx: G2 P2

Meds:

Allergies:

Fluoxetine, Risperidone

Ø

FH: Ø

SH:

ROS:

Disabled; some EtOH

Venous stasis, cellulitis

Exam• BP 147/73, P 83

• Flat affect

• Moon facies

• Buffalo hump

• No muscle wasting, no striae, no bruising

Prior Studies – 8 months prior

TSH 3.7TSH 3.7141

3.83.8

106

2828

2525

0.70.78484

11.911.9

36369.39.3 282282

CaCa++ 9 9

Chest X-ray: normalChest X-ray: normal

ECG: normalECG: normal

Differential Dx for Severe Obesity

• Dietary

• Social/Behavioral

• Inactivity

• Iatrogenic

• Neuro-endocrine

What would you do next?

Key Issues for Bariatric Pre-Operative Evaluation

• When should you suspect a non-lifestyle associated etiology for morbid obesity?

• What is the most efficient diagnostic strategy to evaluate for a neuro-hormonal cause?

• What are the most important medical risks to this patient if she undergoes bariatric surgery?

Key Issues for Bariatric Pre-Operative Evaluation

• When should you suspect a non-lifestyle associated etiology for morbid obesity?

• What is the most efficient diagnostic strategy to evaluate for a neuro-hormonal cause?

• What are the most important medical risks to this patient if she undergoes bariatric surgery?

Severe Obesity = BMI 40

NHLBI 2000NHLBI 2000

Treatment Guidelines for Obesity

Prevalence of Severe Obesity is Increasing

Pharmacotherapy: only 3 to 5 kg Average Weight Loss

Bariatric Surgery Reduces Obesity-Associated Morbidity

Surgery May Improve Longevity

“Ideal” Bariatric Surgery Candidates

Cleve Clin J Med 2006;73(11).Cleve Clin J Med 2006;73(11).

HMO/Medicare Payment for Bariatric Surgery• BMI > 40 for 2 to 5 years

– BMI > 35 if CAD, DM, HTN, sleep apnea

• Repeated failures of supervised weight loss (6 months duration)

• Letter of medical necessity• “Treatable metabolic causes ruled out”

– “Thyroid panel”– “adrenal disorders”

Roux-en-Y Combines Restriction with Malabsorption

Acute Complication Rates for Bariatric Surgery

Long Term Complications• Anastomotic Stricture

• Marginal ulcers

• Bowel obstruction

• Cholelithiasis

• Nutritional Deficiencies

Nutritional Deficiencies are Common after Malabsorptive Procedures• Iron

• Vitamin B-12

• Calcium

• Vitamin D

Multitamins will not adequately treat Multitamins will not adequately treat iron and B-12 deficienciesiron and B-12 deficiencies

Key Issues for Bariatric Pre-Operative Evaluation

• When should you suspect a non-lifestyle associated etiology for morbid obesity?

• What is the most efficient diagnostic strategy to evaluate for a neuro-hormonal cause?

• What are the most important medical risks to this patient if she undergoes bariatric surgery?

Possible Metabolic Causes of Obesity in Our Patient• Hypothyroidism

• Hypothalamic condition

• Cushing’s Syndrome

• Polycystic Ovarian Syndrome

• Pseudohypoparathyroidism

This was my “non-clearance”…

IMPRESSION: A 53-year-old white female without any history of cardiopulmonary disease. Given her lifelong history of morbid obesity in association with and lack of history of diabetes and hypertension, I think it is unlikely that she has Cushing disease or other underlying metabolic disorder….

I think she is at high risk for perioperative delirium given her significant psychiatric history. I think that the surgical team will need to be cautious with administration of narcotics or hypnotics/sedatives.

But Could She Have Cushing’s Syndrome?• Physical exam suggestive of

hypercortisolism–From severe obesity?

–From psychiatric distress?

–From alcoholism?

• No history of glucocorticoid use

Prevalence of Clinical Features of Cushing’s Syndrome• Obesity (90%)

• Neuropsychiatric (85%)

• Hirsutism (75%)

• Bruising (35%)

• Hypertension (85%)

• Diabetes (20%)

Greenspan’s Basic and Clinical Endocrinology, 8Greenspan’s Basic and Clinical Endocrinology, 8thth Edition. Edition.

Validity of Standard Screening Tests for Cushing’s Syndrome• Elevated midnight serum cortisol

–96-100% sensitivity, 100% specificity

• Overnight Dexamethasone Suppression–90-100% sensitivity, 40% specificity

• Elevated 24-hour urinary cortisol excretion

–100% sensitivity, 98% specificity

Accuracy of Screening Tests for Cushing’s Syndrome

J Clin Endocrinol Metab 88:2003.J Clin Endocrinol Metab 88:2003.

My Clinical Suspicion was High Enough to Screen for Cushing’sRECOMMENDATIONS:

1) “I ordered a midnight salivary cortisol test which is very sensitive and has high negative predictive value.”

Recommended Preoperative Testing for Bariatric Surgery• Hematocrit

• Baseline Iron, B-12 levels

• TSH

• A1c (if diabetic control in doubt)

• Creatinine if appropriate

• Baseline ECG and other cardiopulmonary testing if suspect undiagnosed disease

8 Months later…• Test #1: 0.155 ug/dL (normal <0.112)

• Test #2: quantity not sufficient

• Test #3: quantity not sufficient

• Test #4: quantity not sufficient

• Endocrine referral

Dexamethasone Suppression Test Rules-Out Cushing’s• 1mg Dexamethasone at 11PM to 12AM

• 8AM Cortisol level–1mcg/dL

• <8% of patients with Cushing’s show suppression to < 2 mcg/dL

• 100% sensitivity if suppress to less than 1.2 mcg/dL

Take-Home Points• Severe Obesity is increasingly prevalent

• Bariatric Surgery will increase in popularity

• Prospective Bariatric Surgery Patients need careful risk assessment and long-term follow-up for complications

• Consider appropriate screening for secondary causes if patient presents with characteristic history, signs