Page 1842 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 131: Hypothermia 1311

WEIGHT LOSS • Prospective Studies Collaboration. Body-mass index and cause-

Recovery from critical illness related to extreme obesity provides an specific mortality in 900,000 adults: prospective studies. Lancet.
opportunity to engage the patient in a long-term plan to achieve weight 2009;373(9669):1083-1096.
loss. Referral to a weight-loss specialist is indicated. In addition to • Salome CM, King GG, Berend N. Physiology of obesity and effects
dietary counseling and physical activity (insofar as possible), available on lung function. J Appl Physiol. 2010;108:206-211.
medical therapies include a variety of appetite-suppressant and antia- • The Longitudinal Assessment of Bariatric Surgery (LABS)
bsorptive medications. Unfortunately, although short-term success is Consortium. Perioperative safety in the longitudinal assessment
frequent with nonsurgical management, significant long-term weight of bariatric surgery. N Engl J Med. 2009;361:445-454.
loss is uncommon. Therefore, careful consideration should be given to
the option of surgical therapy. Laparoscopic adjustable gastric banding
and laparoscopic or open Roux-en-Y gastric bypass procedures are per- REFERENCES
formed most commonly, although other techniques are available, and
the relative merits of these respective procedures are debated amongst Complete references available online at www.mhprofessional.com/hall
practitioners. Increasing evidence suggests a long-term mortality benefit
for properly selected patients who undergo bariatric surgery when com-
pared with matched controls, as well as improvements in or resolution
of diabetes, obstructive sleep apnea, and various cardiovascular risk CHAPTER Hypothermia
factors. 49,50 Overall perioperative mortality for properly selected patients
is low (<1%). Careful preoperative evaluation and consultation with Zoulficar Kobeissi
51
an experienced surgeon is necessary to exclude patients in whom the 131 Janice L. Zimmerman
potential benefit of surgery is exceeded by the risk (eg, older patients
with cor pulmonale).

DOES OBESITY INFLUENCE THE OUTCOME KEY POINTS
OF CRITICALLY ILL PATIENTS?
• Accidental hypothermia results from the unintentional decrease in core
Obesity has obviously detrimental effects on health across many body temperature to lower than 35°C (95°F) and can be classified as mild
domains, including an increase in the rate of malignancies and an (32.2-35°C, or 90-95°F), moderate (28-32.2°C, 82-90°F), or severe
increase in mortality rate. The influence of obesity on outcome of (<28°C, 82°F).
patients undergoing intensive care is less clear. Whereas some inves- • Although hypothermia from environmental exposure is common,
tigators have found an increased mortality rate and longer length of several medical conditions may also predispose to hypothermia
ICU stay with extreme obesity, many others have reported outcomes necessitating hospitalization and admission to the intensive care unit.
52
that are no different or even improved when compared with nonobese
patients, and the preponderance of evidence to date suggests that obesity • Individuals at highest risk for hypothermia include the homeless,
is not itself associated with worse outcomes from critical illness. 53,54 Our the mentally ill, trauma victims, outdoor workers, those at the
recommendation is that the presence or absence of obesity should not extremes of age, those with serious underlying medical conditions,
be considered in assessing a patient’s prognosis. and those with ethanol or drug intoxication.
• Multiple organ systems are affected by hypothermia: clinical manifes-
tations depend on the underlying cause and core body temperature.
Below 30°C (86°F), shivering ceases, level of consciousness progres-
KEY REFERENCES sively declines, and cardiac arrhythmias become more common.
• In the initial stages, wet clothing should be removed promptly,
• Dickerson RN, Drover JW. Monitoring nutrition therapy in the continued heat loss must be prevented, and any underlying illness
critically ill patient with obesity. JPEN. 2011;35:44S. should be identified and treated.
• Flegal KM, Carroll MD, Ogden CL, et al. Prevalence and trends in • Rewarming is the primary treatment for moderate to severe hypo-
obesity among US adults, 1999-2008. JAMA. 2010;303(3):235-241. thermia. For patients with a core body temperature above 32°C
• Hogue CW Jr, Stearns JD, Colantuoni E, et al. The impact of obe- (90°F), passive and active external rewarming and supportive ther-
sity on outcomes after critical illness: a meta-analysis. Intensive apies are preferred; for patients with lower temperatures and those
Care Med. 2009;35:1152-1170. with hemodynamic instability, active core rewarming using body
• Kaw R, Hernandez AV, Walker E, et al. Determinants of hypercap- cavity lavage or extracorporeal blood warming may be considered.
nea in obese patients with obstructive sleep apnea: a systematic • In addition to rewarming, all patients with hypothermia need con-
review of metaanalysis of cohort studies. Chest. 2009;136:787-796. tinuous monitoring of cardiac status, intensive fluid resuscitation,
• Kristensen MS. Airway management and morbid obesity. Eur J and circulatory support.
Anaesthesiol. 2010;27:923-927.
• Lemyze M, Mallat J, Duhamel A, et al. Effects of sitting position
and applied positive end-expiratory pressure on respiratory Hypothermia is defined as a core body temperature lower than 35°C
mechanics of critically ill obese patients receiving mechanical (<95°F). The severity of hypothermia is indicated by the degree to
ventilation. Crit Care Med. 2013;41(11):2592-2599. which the core body temperature is lowered and is classified as mild,
• Malbrain ML, Chiumello D, Pelosi P, et al. Prevalence of intra- moderate, or severe. Several medical conditions may increase the risk
abdominal hypertension in critically ill patients: a multicenter of hypothermia. Individuals at the extremes of age are at greatest risk.
epidemiological study. Intensive Care Med. 2004;30:822-829. Risk of death from hypothermia is related to age, preexisting illnesses,
1
• Mokhlesi B. Obesity hypoventilation syndrome: a state-of-the-art nutritional status, and alcohol and drug intoxication. In cases of severe
review. Respiratory Care. 2010;55(10):1347-1365. hypothermia, prompt intervention with rapid rewarming is crucial and
may be life saving. This chapter discusses the pathophysiology, risk

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