UBP 1.2 (Short Form): Endocrine -- Obesity

Question 1

Would you allow this case to be performed in an outpatient facility?

(A 36 yo 188 kg 5’4” female is scheduled for open umbilical hernia repair. She has a history of diabetes mellitus, hypertension, gastric reflux, and asthma. She is taking metformin. VS: BP = 148/89, P = 78, T = 37 C, R = 22)

Answer 1

• In making a decision concerning the appropriateness of ambulatory surgery for this super morbidly obese patient, I would consider several factors including:
  
  1. the potential for undiagnosed OSA;
  2. anatomical and physiological abnormalities;
  3. the extent and severity of any coexisting disease, and whether medical management is optimized;
  4. the nature of the surgical procedure (i.e. superficial, abdominal, peripheral);
  5. intra-operative anesthetic requirements (i.e. local, regional, sedation, general);
  6. the age of the patient;
  7. the capabilities of the outpatient facility (i.e. emergency airway and respiratory care equipment, laboratory and radiology capabilities or access, transfer agreement with an inpatient facility);
  8. the adequacy of post-discharge care (i.e. family members, friends, etc.); and
  9. the anticipated post-operative opioid requirements.
• Therefore, I would begin by performing a thorough history and physical exam to determine the extent and severity of her coexisting disease, including the potential presence of OSA.
• I would then proceed with the case if the patient was medically optimized and there was no history suggestive of OSA.
• If I suspected OSA, I would be willing to proceed as long as the facility capabilities and post-discharge care were adequate and the patient’s post-operative pain could be managed predominantly using non-opioid analgesic techniques (i.e. local, regional, NSAIDs, etc.)

Question 2

Know BMI Classification

Answer 2

BMI = kg/m²

Normal = 18.5-24.9 kg/m²

Overweight = 25.0-29.9

Obese (class 1) = 30.0-34.9

Obese (class 2) = 35.0-39.9

Obese (class 3) = 40.0-49.9

Super-obese = >/= 50

Question 3

How would you identify those patients with undiagnosed OSA?

Answer 3

Recognizing that 20% of patients may suffer from OSA, with up to 80% of them remaining undiagnosed,

I would employ the STOP-BANG criteria to help in identifying those at increased risk of peri-operative complications associated with OSA –

(i.e., respiratory depression, airway obstruction, hypoxia, and hypercarbia).

The STOP-BANG screening tool utilizes the presence of –

• loud Snoring (louder than talking or loud enough to be heard through a closed door),
• daytime Tiredness,
• Observed apnea (witnessed apnea during sleep),
• high blood Pressure,
• a BMI > 35 kg/m²,
• Age > 50 years,
• Neck circumference > 40 cm, and
• male Gender to determine the risk of undiagnosed OSA.

The presence of < 3 of these criteria is associated with a LOW risk of OSA,

while the presence of 3 or more is associated with a HIGH risk of OSA.

Furthermore, the presence of 5-8 of these criteria is associated with a HIGH probability of moderate-to-severe OSA

Question 4

You discover that the patient has moderate-to-severe OSA, and the case is scheduled at the hospital.

What potential perioperative complications are you anticipating with this patient?

(A 36 yo 188 kg 5’4” female is scheduled for open umbilical hernia repair. She has a history of diabetes mellitus, hypertension, gastric reflux, and asthma. She is taking metformin. VS: BP = 148/89, P = 78, T = 37 C, R = 22)

Answer 4

The potential complications that I would be anticipating include –

1. difficult airway management,
2. aspiration,
3. bronchospasm,
4. labile blood pressure,
5. hyperglycemia,
6. hypoglycemia, and
7. difficulty in evaluating cardiopulmonary status due to a sedentary lifestyle and/or diabetic neuropathy.

Other potential complications associated with morbid obesity include those related to –

1. patient positioning,
2. rapid desaturation with apnea (decreased FRC),
3. obesity hypoventilation syndrome (Pickwickian syndrome),
4. OSA,
5. postoperative apnea,
6. metabolic syndrome,
7. type II diabetes,
8. hypertension,
9. coronary artery disease,
10. stroke,
11. altered drug effects,
12. DVT,
13. pulmonary embolism,
14. osteoarthritis, and
15. nonalcoholic fatty liver disease

Question 5

What preoperative lab work would you order?

Would you require an EKG? CXR? PFTs? ABG? LFTs?

(A 36 yo 188 kg 5’4” female is scheduled for open umbilical hernia repair. She has a history of diabetes mellitus, hypertension, gastric reflux, and asthma. She is taking metformin. VS: BP = 148/89, P = 78, T = 37 C, R = 22)

Answer 5

Given the fact that this is a low risk surgical procedure, the only preoperative lab work I would require is – a pregnancy test and a serum glucose level.

In addition to this lab work, I would review the patient’s history for –

• weight change,
• past difficult airway management, and
• a diagnosis or symptoms suggestive of OSA
• (the results of a sleep study would be helpful in identifying patient’s at increased risk of rapid desaturation and difficult airway management).

This patient’s morbid obesity and coexisting diseases may result in abnormalities in the EKG, CXR, ABG, PFTs, LFTs, and even H/H.

However, for this low risk procedure, these results would be unlikely to alter my anesthetic plan.

Therefore, I would only require a more extensive evaluation if there were further medical indication or if the patient were undergoing a higher risk procedure.

Question 6

What premedications would you give?

(A 36 yo 188 kg 5’4” female is scheduled for open umbilical hernia repair. She has a history of diabetes mellitus, hypertension, gastric reflux, and asthma. She is taking metformin. VS: BP = 148/89, P = 78, T = 37 C, R = 22)

Answer 6

Since her obesity, possible diabetic neuropathy, and gastric reflux place her at increased risk of aspiration,

I would consider giving – an H2-receptor agonist, metoclopramide, and possibly a nonparticulate antacid (could also administer a proton pump inhibitor, with the first dose given the night before surgery and the second dose given the morning of surgery).

Since obesity also increases the risk of wound infection and DVT, I would discuss – antibiotic and DVT prophylaxis with the surgeon.

Finally, I would consider – a breathing treatment to optimize her asthma.

Question 7

She is extremely anxious and is crying.

Would you give midazolam and fentanyl?

(A 36 yo 188 kg 5’4” female is scheduled for open umbilical hernia repair. She has a history of diabetes mellitus, hypertension, gastric reflux, and asthma. She is taking metformin. VS: BP = 148/89, P = 78, T = 37 C, R = 22)

Answer 7

I would consider carefully titrating in some midazolam, since excessive anxiety and crying may inhibit patient cooperation and complicate airway conditions should intubation and/or ventilation prove difficult.

However, if I were concerned about the presence of undiagnosed obstructive sleep apnea, I would consider the risks of respiratory depression before administering any sedatives.

Question 8

You are appropriately concerned about the patient’s cardiac status, given her concomitant disease.

How would you evaluate her?

• (A 36 yo 188 kg 5’4” female is scheduled for open umbilical hernia repair. She has a history of diabetes mellitus, hypertension, gastric reflux, and asthma. She is taking metformin. VS: BP = 148/89, P = 78, T = 37 C, R = 22)*
• (Know RCRI**)*

Answer 8

I would start with a thorough history and physical,

ruling out any active cardiac conditions such as –

unstable or severe angina, decompensated heart failure, severe arrhythmias, or severe valvular disease.

I would then assess her perioperative risk for a major adverse cardiac event (MACE) by – utilizing the revised cardiac risk index (RCRI), where 2 or more of the following findings is associated with elevated risk of MACE:

1. insulin dependent diabetes mellitus,
2. history of ischemic heart disease,
3. history of compensated or prior heart failure,
4. history of cerebral vascular disease,
5. renal insufficiency, or
6. supra-inguinal vascular, intraperitoneal, or intrathoracic surgery.

Since her insulin dependent diabetes mellitus and intraperitoneal surgery place her at elevated risk for MACE, I would ask about any past or recent cardiac evaluation and attempt to determine her functional capacity, which may be difficult since she is very likely sedentary.

Unfortunately, if her diabetes has led to diabetic neuropathy, she may not experience the typical warning signs of myocardium at risk, such as angina.

If her functional capacity were >/= 4 METS (e.g. climb a flight of stairs or walk on level ground at 4 mph without symptoms), I would proceed with surgery without further cardiac testing.

If her functional capacity were < 4 METS or unknown, I would have a discussion with the patient and surgeon as to whether the results of additional testing would impact decision making (e.g. Will it alter the surgeon’s willingness to proceed with surgery? or Is the patient willing to undergo CABG or PCI?).

If the results would impact decision making, then I would delay the case for pharmacologic stress testing.

If on the other hand, the results of further testing would not change management, then I would proceed with surgery.