CCP 331 Bariatrics π© Flashcards
How to dose paralytics in obesity
π΅π΅π΅ MONEY SLIDE π΅π΅π΅
- Roc = ideal body weight (IBW)
2. Suxx = total body weight (TBW)
Overweight definition (BMI)
BMI 25-30
obesity definition
BMI of β₯30
severe obesity definition
BMI β₯40 (or β₯35 in presence of comorbidities)
Define Body mass index
- simple calculation using a personβs height and weight
2. BMI = kg/m2 (weight in kg / height in metres squared)
prevalence of obesity in Canada
- 40% adults overweight
- 30% adults obese
- 3% adults βmorbidly obeseβ
- 27% adults normal/healthy
Vital Signs in Obesity Emergency Management
πππMEGA PEARLπππ
- NIBP readings can be falsely elevated in obese patients as improperly placed small cuff size often overestimates BP
- A βnormalβ NIBP could represent a shock state in an obese adult
- Consider placing an early arterial line to obtain and trend accurate BP readings over time
- The Shock Index can be helpful in making a diagnosis of occult shock in obese and non-obese patients. Shock Index = HR/SBP; Any number > 1 suggests occult shock
ECG Alterations in Obesity Emergency Management
- Low voltages β d/t size of their chest wall
- Longer QT intervals sometimes >500ms as a result of obesity alone
- Signs of LVH β (consider obesity-associated cardiomyopathy)
Important Pulmonary Physiology changes in Obesity
π΅π΅π΅ MONEY SLIDE π΅π΅π΅
- β respiratory reserve is 2Β° to β total lung capacity and β FRC. The β reserve compromises an obese patientβs ability to tolerate respiratory insults such as pneumonia
- β airway pressures are a result of β airway resistance (heavier chest walls, β abdominal girth, atelactatic lung bases). The β pressures lead to: Smaller oxygen reserves at baseline, β WOB, Shorter time to desaturation during induction and a shorter Safe Apnea Time
- β incidence of hypoxemia and hypercapnia at baseline
- β risk of aspiration pneumonitis
- More difficult to ventilate with BMV
V.A.P.O.R.S mnemonic for factors that need to be considered in planning and executing a safe and successful intubation for critically ill obese patients
Ventilation (can you bag mask this patient?)
Acidosis
Pressures (BP, peak pressures, plateau pressures etc)
Oxygenation (safe apnea time)
Regurgitation
Shock Index (see above)
Pharmacologic Adjustments in Obesity Emergency Management
π΅π΅π΅ MONEY SLIDE π΅π΅π΅
- Lipophilic drugs (eg. Propofol) need to be dosed based on TBW
- Hydrophilic drugs (eg. Ketamine) are dosed based on IBW
- ABX also have different dosing profiles based on their class
Radiology/Imaging in Obesity Emergency Management
π΅π΅π΅ MONEY SLIDE π΅π΅π΅
- The FAST scan may be indeterminate or falsely negative given the depth of penetration required to visualize Morrisonβs pouch
- The chest x-ray will be under-penetrated
- CT images will be more difficult for the radiologist to interpret and as a result, injuries are more often missed.
describe βrampingβ in Obesity Emergency Management
- Build a big ramp behind the patientβs head and torso to achieve an ear-to-sternal-notch configuration with towels/blankets or commercially available products
- position the patient in reverse Trendelenburg to take the weight of the panus off the chest
ANATOMIC changes to the airway/respiratory system of the obese patient
π΅π΅π΅ MONEY SLIDE π΅π΅π΅
- β neck circumference d/t excess cervical adipose tissue β upper airway collapse
- β soft tissue deposition in the relatively closed space of the oropharyngeal cavity β pharyngeal airway narrowing
- β neck circumference + dorsocervical fat deposition β limited neck extension
- Fat, obese neck β difficult access for a surgical airway
PHYSIOLOGIC changes to the airway/respiratory system of the obese patient
π΅π΅π΅ MONEY SLIDE π΅π΅π΅
- obese patients have markedly β lung volumes
- for each unit β in BMI, FRC, expiratory reserve volume, VC, TLC, and residual capacity β 0.5% to 5%
- β FRC β closure of small airways and an β in airway resistance β under-ventilated areas of lung, atelectasis, and intrapulmonary shunting β decreased safe apnea time
- obese patients develop VQ mismatch d/t their upper lung zones aerated preferentially, with lower lung zones perfused preferentially
- chest wall compliance is β d/t increase in adipose tissue in the thoracic cage
- Oxygen consumption is ~1.5x higher in the obese patient than in non-obese patient
- d/t the β in O2 consumption and WOB, obese patients CO2 production is also increased
- β pulmonary reserve β rapid onset of hypoxemia during RSI β potential peri-intubation cardiac arrest πππ
discuss Preoxygenation in the bariatric RSI
π§π§π§ ESOTERIC WISDOM π§π§π§
- obese patients have β cardiopulmonary reserve and desaturate rapidly during intubation
- Often, traditional methods of preoxygenation using a NRB or BVM are insufficient in the critically ill obese patient
- NIV is the preferred preoxygenation method. CPAP at 10cmH2O has been shown to β atelectasis, β oxygenation, and β safe apnea time in the obese patient
- BiPAP can also be used to preoxygenate obese patients, but is less well studied than CPAP
- CPAP or BiPAP should be maintained for at least five minutes during the preoxygenation period
- HFNC provides minimal CPAP, no evidence of benefit in preoxygenation prior to RSI for obesity