Diagnosis Made Difficult
Once the patient is situated, the medical staff faces the challenge of how to best assess the patient as accurately as possible. Basic vital signs can be difficult to obtain. With several layers of fat between the arteries and skin surface, pulses can be difficult—if not impossible—to palpate. Blood pressure cuffs must be large enough to avoid obtaining false readings. It can be difficult to auscultate lung sounds and cardiac rhythms; it may also be impossible to assess the abdomen by typical hands-on examination techniques. Even visualizing the entire skin surface can be difficult and time-consuming.
Obtaining diagnostic studies presents yet another challenge: Needles used for drawing blood may not be long enough to reach a vein through the layers of fat. CT and MRI images may not be possible if the gantry does not have a high enough weight rating, and there is also the possibility that the patient simply will not fit into the machine. Because body fat basically places a pillow between internal organs and the sensoring unit, ultrasound images may be impossible to obtain. Even something as simple as a chest X-ray may be difficult to interpret because of the difficulty of trying to diagnose the density difference between infected lung lobes versus the chest around it.
Dr. Allswede says that with the usual preferred diagnostic tools often rendered useless doctors have only two choices: “We can watch and wait, or we can perform invasive procedures.”
When an invasive procedure is necessary, Dr. Allswede cautions, physicians cannot rely on normal body landmarks to aid in location of underlying organs. Procedures such as placement of central lines, chest tubes, and peritoneal lavage can become a guessing game for the physician. “The normal body markings don’t align with body cavities,” he explains. “It becomes more difficult to do landmark locating for procedures.”
ABCs of Treating Obese Patients
Even the most basic medical management can be made difficult by obesity. Management of airway, breathing, and circulation is generally straightforward, and the protocols and procedures are standard; however, in the extremely obese patient problems can arise that are generally unseen in the average patient.
Morbidly obese patients desaturate more quickly than other adults. This can make it even more imperative than usual that a patent airway be obtained and maintained. Obesity makes it more difficult for the physician to visualize the laryngeal structures when attempting to intubate. Further, ventilation is made more difficult because of reduced pulmonary compliance, increased chest wall resistance, increased airway resistance, abnormal diaphragmatic position, and increased upper airway resistance.3
These patients have increased blood volumes, increased cardiac output, increased left ventricular volume, and lowered systemic vascular resistance. They may display atypical cardiac rhythms. Obtaining venous access can be extremely difficult in obese patients.3
Some of these problems can be solved by patient positioning, but some may require improvised techniques and/or specialized equipment.
Drug dosages must be modified for a morbidly obese patient; however, this is not simply a matter of larger body equaling larger dose. The physician must differentiate between fat-soluble and water-soluble medications, and obtain an estimate of the patient’s weight and body mass index to determine the proper dose of any given medication. Having a quick reference chart available for the most commonly used medications may be somewhat helpful, but it would be impossible to anticipate every possible drug-dosing dilemma. Figuring the proper dose can take some time, time that is not always available in a life-threatening situation.