Chapter 54 Considerations for the Patient with Morbid Obesity
In 2005 the World Health Organization indicated that 1.5 billion people over the age of 15 were overweight (body mass index [BMI] >24) and at least 400 million were obese (BMI >29).1 By 2015 an estimated 2.3 billion adults will be overweight, and more than 700 million will be obese.1 In 2008 the rate of obesity among adults averaged 32%2 and was up to 18% for children aged 6 to 19 years.3 While obesity-related mortality rates have many variables, most studies show similar findings: The death rate increases in relation to the degree of obesity and the related comorbidities. On average, an overweight person lives 3 years less and an obese person lives 7 years less than a person of average weight. For those obese persons who also smoke, life expectancy is 14 years less than for a person of average weight.4
Assessing and Treating the Special Needs of the Patient with Morbid Obesity
Airway Management
Bag-Mask
• Higher pressures are required to effectively ventilate the obese patient, and it can be difficult to maintain a good seal with the mask. Two people may be needed to ensure proper positioning and seal of the mask.
• Unless contraindicated, it is best to use an oropharyngeal or nasopharyngeal airway when bag-mask ventilation is required.
Endotracheal Intubation
• Administer the highest possible concentration of oxygen via the best available means prior to intubation.
• The “ramped position” (reverse Trendelenburg) is more effective for optimal glottis visualization than the traditional “sniff” position.5
• Rapid sequence intubation carries a higher risk of aspiration pneumonia in the obese patient.
• When possible, attempt to visualize the vocal cords while the patient is awake to determine if rapid sequence intubation is safe.
• Consider awake intubation for patients who are poor candidates for rapid sequence intubation.
• Nasotracheal intubation is not typically recommended in this population.
• Cricothyrotomy can be extremely difficult in the morbidly obese patient, as traditional landmarks are masked by excess soft tissue and conventional tubes may be too short.
Ventilation
• The heavy noncompliant chest wall of a patient with morbid obesity makes ventilation difficult.
• Static pulmonary compliance is decreased.
• Keeping the head of the bed elevated will facilitate ventilation and decrease the risk of aspiration. For acute management, place the patient in the reverse Trendelenburg position (if possible) to reduce abdominal pressure on the diaphragm and improve chest wall and diaphragm excursion.
• Target oxygen levels may be difficult to reach because of an increase in oxygen consumption.
• Oxygen desaturation occurs quickly in the obese patient because of decreased functional reserve capacity.
Medication Administration
• Dosage of medications used for rapid sequence intubation should be based on lean body mass. Insufficient sedation may occur if ideal body mass is used, and excessive sedation may occur if total body weight is used for dosage calculations.
• Care should be taken with thiopental and benzodiazepines, as they have prolonged effects in the obese patient because of their lipophilicity.
• Subtherapeutic or toxic responses to medication are common.
• Dosing medications can be difficult; some examples of proper dosing are:
• Longer intramuscular needles may be required.
Vascular Access
• Central line placement can be difficult because of obscured anatomic landmarks. The distance from the skin to the vessel is longer in the obese patient than most prepackaged central line kits are designed for, and the angle of approach may be too steep to allow cannulation once the vessel is reached.
• The use of ultrasound when placing an internal jugular central venous catheter will facilitate successful completion of the procedure.
• Peripherally inserted central catheters (PICC) work well in this population, as they are fairly easy to place accurately.
• Avoid the groin for central line access, as many obese patients have intertrigo and this greatly increases the infection risk.
Imaging Studies
• A 2007 study by Massachusetts General Hospital reported that patients who weighed more than 450 pounds experienced repeated delays in diagnosis and treatment because of an inability to obtain standard, modern radiographic studies.6
• Most radiology tables are designed for patients who weigh less than 300 pounds. Some hospitals have tables with weight limits up to 680 pounds, yet patients may still be too large to fit into the opening of the computed tomography or magnetic resonance imaging (MRI) scanners.
• The utility of ultrasound is limited because of reduced transmission of sound waves through the extensive subcutaneous and intraperitoneal adipose tissue.
• More than one film cartridge may be required to obtain a complete image with some diagnostic radiographic procedures.
• Intravenous radioisotopes are weight based, with a maximum allowable safe dose; obese patients may require longer exposures to complete the study while the radioisotope circulates.
• Additional preparations—including longer catheters, sedation, and airway management necessitating additional staff—may need to be considered prior to a procedure.7
Equipment Requiring Bariatric Consideration
The following equipment should be properly sized for the morbidly obese patient:
• Bed; stretcher; wheelchair; recliner; examination table; dental or ear, nose, and throat (ENT) chair; walker; and cane
• Clothing: gown, nonslip socks, wristbands, and incontinence briefs
• Toilets (floor mounted versus wall mounted), commodes, and bed pans
• Ceiling-mounted lifts, lateral transfer systems, and the use of lift teams
• Longer catheters, surgical supplies, and procedural equipment, including longer needles for lumber punctures (5.5 inches)
Staff Safety
In one study, patients with a BMI of 35 made up only 10% of the patient population but were associated with 30% of staff injuries related to patient handling.8 Emergency departments should consider establishing the following practices to reduce the incidence of staff injury:
• Develop bariatric policies and procedures for safety of staff and patient handling.
• Mobilize proper equipment prior to initiating patient care.
• Wait for proper number of staff before trying to assist a bariatric patient.
• Communicate a “game plan” before initiating patient care.10
Under ideal conditions the maximum limit for manual patient handling is 35 pounds. The leg of a 250-pound patient weighs about 39 pounds. Multiple caregivers may be needed for some tasks, such as positioning for urinary catheter insertion.8
Disease Risk in the Obese Population
Endocrine System
Prediabetes
In 2010, 79 million Americans over the age of 20 years were classified as having “prediabetes,”11 and obesity increases this risk. The condition is defined by elevated blood glucose levels not high enough to be diagnosed as diabetes.11
