EM Special 7: Morbidly Obese Patient

Question 1

Obesity is defined as

Answer 1

WHO:
obese: BMI ≥30 kg/m2
morbidly obese: BMI ≥40 kg/m2

Asia-Pacific Guidlines:
obese: BMI ≥25 kg/m2

Question 2

Diagnostic criteria for Obesity Hypoventilation Syndrome

Answer 2

BMI 30 kg/m2
Daytime PaCO2 >45 mm Hg
Associated sleep-related breathing disorder (OSA-hypopnea syndrome or sleep hypoventilation or both)
Absence of other known causes of hypoventilation

Question 3

formula for weight estimation based on mid-arm circumference in school-age children

Answer 3

weight (kg) = (mid-arm circumference [cm] - 10) x 3

Question 4

the standard adult blood pressure cuff is too short for patients with an arm circumference of

Answer 4

32 cm or larger

Patients who are overweight or obese will require cuffs larger in size

Question 5

AHA recommendation of cuff widths when evaluating BP in obese

Answer 5

arm circuference 35-44 cm: 16 cm width
arm circumference 45-52 cm: 20 cm width
patients with short upper arm length: 16 cm width

Question 6

Some common drugs that use ideal body weight in dosing

Answer 6

pencillins & cephalosporins
corticosteroids & H2-blockers
Digoxin & beta blockers
PROPOFOL
FENTANYL**
**MIDAZOLAM & *lorazepam
atracurium, vecuronium
phenytoin
linezolid

**initial dose still based on total body weight*

Question 7

Some common drugs that use total body weight in dosing

Answer 7

ROCURONIUM
ENOXAPARIN
succinylcholine
unfractionated heparin
vancomycin

Question 8

how to determine ideal body weight by *Devine formula**?

Answer 8

male weight = 50 kg + 2.3 kg (each inch >5 feet)

female weight = 45.5 kg + 2.3 kg (each inch >5 feet)

Question 9

drugs whose initial dose should be based on total body weight but whose subsequent doses should be based on ideal body weight

Answer 9

Fentanyl and benzodiazepines
- lipophilic and have a prolonged half-life in obese patietns

Question 10

remarks on femoral venous catheterization

Answer 10

in general, there is an increased incidence of infection and DVT when using the femoral approach.
If this proves to be the only option, then use this site.

Question 11

remarks on internal jugular venous catheterization

Answer 11

the internal jugular vein can be accessed with equal success to the subclavian approach in patietns who are obese

the success rate might be increased with the head maintained in the neutral position, thereby reducing the risk of overlap of the IJV over the carotid artery

Question 12

remarks on procedural sedation in the obese

Answer 12

Give procedural sedation drugs and pain medications cautiously. Select doses at the lower end of the range, and titrate to effect.
Local and regional anesthesia might be considered for complicated or prolonged procedures

Question 13

characteristics that render obese patients more prone to aspiration during airway management

Answer 13

• increased intra-abdominal pressure
• increased incidence of hiatal hernia
• GERD

Question 14

true or false:
Patients who are obese will desaturate more rapidly after preoxygenation than their lean counterparts.

Answer 14

TRUE
When no cervical spine injury is suspected, desaturation may be partially prevented by keeping the patient in a 25-degree head-up position during preoxygenation

Question 15

maneuver recommended for opening airway in morbidly obese patients

Answer 15

Two-person bag-valve mask with a two-handed bilateral jaw thrust is recommended in patients who are morbidly obese.

Question 16

true or false:
Obesity is a contraindication for rapid-sequence intubation (RSI)

Answer 16

FALSE
It is not.
Advance preparation is critical, and assessment for a potential difficult airway is of utmost importance

Question 17

true or false:
The “sniffing” position results in optimal positioning for laryngoscopy in patients who are obese

Answer 17

FALSE
“Sniffing” position results in suboptimal view
and this my also confound results and falsely worsen graded views

The “ramping” position offers improved intubation condition in patients who are morbidly obese.
- achieved by placing multiple folded blankets under the upper body, head, and neck until the external auditory meatus and the sternal notch are horizontally aligned

Another option is intubating with the patient semi-upright

Question 18

The relative benefits and risks of the awake intubation approach must be weighed against the merits of RSI, which are:

Answer 18

• reduction of risk of aspiration
• improved intubating conditions
• easier insertion of advanced and rescue airway devices

Question 19

Until the proper size tracheostomy tube is located, a _________ ET tube passed through a cricothyroidotomy incision may serve as a temporizing measure

Answer 19

6-mm-inner-diameter ET tube

Question 20

with respect to ventilator management, calculate tidal volume using

Answer 20

ideal body weight and begin with volumes of 6-8 mL/kg of ideal body weight

Question 21

remarks on trauma in obese patients

Answer 21

MORE
rib fractures
pelvic fractures
pulmonary contusions
extremity fractures
risk of death

LESS
head injuries
liver injuries

Question 22

remarks on trauma on mildly overweight patients

Answer 22

less prone to intra-abdominal injury because of the protective effect of the abdominal fat, known as “cushion effect”