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Inadvertent Perioperative Hypothermia During Orthopedic Surgery

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Overall, in the last 2 decades, the incidence of inadvertent perioperative hypothermia has decreased, mainly due to aggressive intraoperative management.7 In spite of this, studies have shown that perioperative hypothermia remains a significant problem in patients undergoing orthopedic procedures. In a recent community hospital study conducted by the National Association for Healthcare Quality that included 4124 orthopedic patients undergoing elective surgery, it was shown that, in spite of 99% compliance to the AMA-PCPI recommendation, 7.7% of orthopedic patients were found to be hypothermic.6

Management of hypothermia has long been an integral component of “damage control surgery” and resuscitation during polytrauma, which aims to aggressively minimize hypovolemic shock and limit the development of the lethal triad of hypothermia, coagulopathy, and acidosis.8 However, critical references to prevention and management of inadvertent perioperative hypothermia are lacking in the orthopedic literature on elective surgical procedures. This review aims to bridge this knowledge gap.

Unless otherwise specified, inadvertent perioperative hypothermia in this article refers to the core body temperature. In contrast, peripheral/limb hypothermia refers primarily to the effect of tourniquet application to the involved limb and the effect after deflation of the tourniquet on core body temperature.

RISK FACTORS

There are several measurable risk factors that can contribute to inadvertent perioperative hypothermia, which can be subdivided into 3 groups: patient-related risk factors, anesthesia-related risk factors, and procedure-related risk factors (Table 1).5,9-11 It is important to note that in any given patient a combination of 2 or more risk factors predisposes them to developing inadvertent perioperative hypothermia. Conceptualizing the etiology of inadvertent perioperative hypothermia in this way helps to plan a multipronged strategy to prevent it from occurring in the first place. Some of the important risk factors for inadvertent perioperative hypothermia are discussed below.

Table 1. Risk Factors for Perioperative Hypothermia

Patient-Related Risk Factors

Anesthesia-Related Risk Factors

Procedure-Specific Risk Factors

  • High severity of illness
  • Neurological disorder (Alzheimer’s etc.)
  • Male
  • Age >65 years
  • Weight loss
  • Anemia
  • Chronic renal failure
  • Low body mass index
  • Type of anesthesia
  • Intravenous fluid temperature
  • Tourniquet application
  • Duration of surgery
  • Irrigation fluid temperature

To identify patient-related risk factors, researchers from the University of Louisville conducted a study including 2138 operative patients who became hypothermic after admission, of whom 27% underwent orthopedic and spine procedures.9 The patient-related risk factors identified were a high severity of illness on admission (odds ratio, 2.81; 95% CI, 2.28-3.47), presence of a neurological disorder such as Alzheimer’s disease (odds ratio, 1.71; 95% CI,1.06-2.78), male sex (odds ratio, 1.65; 95% CI, 1.36-2.01), age >65 years (odds ratio, 1.61; 95% CI, 1.33-1.96), recent weight loss (odds ratio, 1.60; 95% CI, 1.04-2.48), anemia (odds ratio, 1.49; 95% CI, 1.12-1.98), and chronic renal failure (odds ratio, 1.43; 95% CI, 1.07-1.92). Interestingly, diabetes mellitus without end-stage organ failure was not found to be a significant risk factor (odds ratio, 0.58; 95% CI, 0.44-0.75). It is also important to note that some of these risk factors identified to contribute to perioperative hypothermia are dependent on each other and others are independent of each other. For example, chronic renal failure and anemia are dependent risk factors. In contrast, age >65 years and low body mass index as risk factors of perioperative hypothermia are independent of each other.

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