Page 1841 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

1310 PART 11: Special Problems in Critical Care

OTHER PROBLEMS IN THE DELIVERY OF CRITICAL CARE of this sedative or the accompanying analgesic is still desirable,
■ ESTABLISHING VASCULAR ACCESS tion or conversion to a validated regimen of intermittent sedative
whether it be by daily interruption of continuous intravenous seda-

Establishing intravenous access may be difficult in the extremely obese administration.
venous line. The increased distance from skin to blood vessel makes any ■ MINIMIZING COMPLICATIONS OF CRITICAL ILLNESS
patient, beginning with the frequent inability to place a peripheral intra-
attempt to cannulate a central vein more difficult, while the sharp angle Because of the significantly elevated risk of venous thromboembo-
required at times to cannulate the subclavian and femoral veins may lism in obesity, an aggressive approach to prophylaxis is merited.
make it impossible for the operator to pass the wire and/or dilator. In Unfortunately, data on this subject are lacking even in the general
some patients, the needle and the introducer may be too short for the medical ICU population, and a survey of surgeons who perform
subclavian site. The femoral site should be used as a last resort because bariatric surgery showed wide variation in practice. We recom-
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of the increased risk of infection and thrombosis associated with this mend following the ACCP guidelines for prophylaxis in the bariatric
site; in addition, this site is frequently inaccessible because of inter- surgery patient. This guideline recommends the use of low molecu-
trigo. The internal jugular vein is therefore generally the site of choice lar weight heparin, low dose unfractionated heparin three times
for extremely obese patients, even with the difficulties imposed by a daily, fondaparinux, or the combination of one of these agents with
short, thick neck. We recommend the use of real-time ultrasonography optimally used intermittent pneumatic compression. Higher doses
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when possible. than usual may be required (see Chaps. 5 and 39).
■ NUTRITIONAL SUPPORT increased in the obese patient due to increased intraabdominal pressure
Most studies suggest that the risk of aspiration of gastric contents is
Initially, critically ill obese patients exhibit less lipolysis and fat oxidation and the high volume and low pH of gastric contents in such patients.
than nonobese subjects. This decreased ability to mobilize fat increases This has implications not only for intubation but also for routine nursing
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protein breakdown to fuel gluconeogenesis and, hence, ensure adequate and feeding. We recommend that all extremely obese patients be fed and
carbohydrates for energy. An increased risk for protein malnutrition nursed in the semi-upright position.
healing, and lean muscle mass. However, it appears that this impairment ■ NURSING ISSUES
results, with potentially detrimental effects on immune function, wound
in lipolysis and fat oxidation is short-lived, and that subsequently obese There are a number of challenges involved in caring for the critically ill
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patients are able to utilize their significant fat stores for energy in the patient who is obese, 47,48 some of which are highlighted in Table 130-2. It is
setting of hypocaloric feeding, an approach that improves insulin sensi- important to emphasize that the care of patients with extreme obesity
tivity and glycemic control and minimizes the risks of hypercapnea and is likely to be much more successful and also safer and less frustrating
fluid retention. In fact, several trials of carefully controlled hypocaloric for the caregivers if attention is paid to equipment and staffing issues.
nutritional support in which adequate protein was supplied demon- The bariatric bed is an extremely important component of the care
strated that chronically critically ill patients receiving such a regimen plan, as are the equipment necessary for the safe and smooth transfer
had nitrogen balance comparable to those patients receiving conven- of patients. The latter include bariatric stand assist lifts, seating transfer
tional total parenteral nutrition. aids, full-body slings, the overhead trapeze, and a variety of other equip-
We recommend following the 2009 guidelines of the Society of ment. It is critical that patient transfers are performed with adequate
Critical Care Medicine and the American Society for Parenteral and staffing in order to prevent injury to the patient or staff. The services of a
Enteral Nutrition. This guideline recommends the provision of approx- lift team should be employed when such a service is available. A culture
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imately 60% to 70% of targeted energy requirements, or 11 to 14 kcal/kg of teamwork and sensitivity is helpful when caring for such patients,
actual body weight per day. Protein should be administered to patients as with any patient with greater than usual needs, and the increased
with obesity class I and II at a dose of approximately 2 g/kg ideal body demands placed on nursing in order to accomplish routine tasks should
weight daily, while patients with obesity class III should receive at least be taken into consideration by nursing leadership and by the patient’s
2.5 g/kg ideal body weight. Indirect calorimetry should be considered treating physicians.
to guide nutritional support because of the unreliability of conventional
equations in this setting.
■ DRUG DOSING TABLE 130-2 Nursing Considerations in the Extremely Obese Patient
With Critical Illness
A variety of alterations in pharmacokinetics have been described in Monitoring concerns
obese patients. In general, the volume of distribution for drugs with Limitations in the physical examination
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greater lipophilicity is increased. There are notable exceptions, however, Variable electrocardiogram lead placement
thus illustrating the importance of other factors, such as plasma protein Difficulty obtaining accurate noninvasive blood pressure measurements (consider
binding, in the distribution of drugs. Variable alterations in enzymatic forearm cuff)
and antioxidant systems have been described, and difficulties in estimat-
ing renal clearance rates have been described. Increased difficulty performing bedside procedures (intravenous lines, bladder catheters, etc)
This tremendous intersubject variability, combined with important Increased risk of skin and soft tissue injury
differences between drugs make generalizations about the dosing of Skin breakdown and infection, particularly in skin folds
individual medications impossible. Drugs with a narrow therapeutic Unusually located pressure sores from bed posts, equipment, etc
window such as theophylline and digoxin may confer toxicity when Venous stasis ulcers and cellulitis
dosed according to total body weight. Reference to published guide- Challenges with patient positioning and mobilization
lines for individual drugs is recommended, as is close monitoring of Routine positioning and bathing
clinically available serum drug levels. Because of data indicating an Bedside procedures and radiology
increased volume of distribution and prolonged half-life for mid- Physical therapy
azolam in obese subjects and an apparent lack of accumulation for “Road trips” to other locations
propofol when given as a general anesthetic, we prefer propofol as a Increased demands on staff to deliver routine care
continuous intravenous sedative, when this method of administra-
tion is indicated. 43,44 A strategy to prevent any potential accumulation Potential for injury to patient or staff during transfer

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