Anita Volpe, DNP
2011 DNP Graduate
Decreasing the Incidence of Inadvertent Perioperative Hypothermia: A Quality Improvement Study
Hypothermia is a complication that surgical patients commonly face within the perioperative environment. The exposure to hypothermia can have significant impact on surgical morbidity and mortality leading to untoward surgical outcomes. These untoward surgical outcomes range from increased length of stay to death, with a host of varying sequela between these two ends of the spectrum. While hypothermia is a complication that arises within the perioperative period interventions are available to markedly reduce its occurrence. The research literature is clear about the incidence, risk, and outcomes of inadvertent perioperative hypothermia (I PH), yet it remains a consistent but preventable complication for patients undergoing surgery.
Hypothermia is defined as core body temperature below 360 Celsius1 (Andrzejowski, Hoyle, Eapen, & Turnbull, 2008; Cory, Fossum, Donaldson, Francis, & Davis, 1998; Defina & Lincoln, 1998; Flores-Maldonado, Medina-Escobedo, Rios-Rodriguez, & FernandezDominguez, 2001; Hoda & Gralf, 2008; Kurz, Sessler, & Lenhardt, 1996; Mahoney & Odom, 1999; Summers, 1992; Weirich, 2008). During the first hour of surgery, core body temperature can drop.0.5 to 1.50 (Bitner, Hilde, Hall, & Duvendack, 2007; Wagner, 2006a). A loss of one degree or more can lead to untoward surgical outcomes (Sessler, 1997).
Up to 40% of surgical patients are not monitored for hypothermia within the perioperative setting (Sessler, 1997). The same author noted patients who receive spinal or epidural anesthesia do not feel the sensation of cold. None the less, these patients are among those who are infrequently monitored for hypothermia, and as such, their temperature status is unknown (Sessler, 1997). Estimates suggest that only 26% of surgical patients who have identifiable risks for hypothermia actually receive an intervention to prevent its occurrence (Williamson, 2007). A significant percentage (30-40%) of patients are hypothermic upon arrival to the post anesthesia care unit (PACU) and an estimated 14 million surgical patients annually become hypothermic (Mahoney, 2005; Williamson, 2007). A core body temperature of less than 35S upon arrival to the PACU places the patient at a four-fold risk of mortality compared to normothermic patients (Backster, Teo, Swift, Polk, Jr, & Harken, 2007). Despite arrival to the PACU in a state of normothermia, patients may develop hypothermia losing up to 1.50 in one hour (Cory et aI., 1998).
Surgical site infections (SSI) are responsible for 40% of infectious complications in the surgical population. Surgical patients are most prone to the development of SSI’s during the immediate surgical period (Melling, Ali, Scott, and Leaper, 2001). Frank (2001), Forbes et al. (2009), and Melling et al. (2001) reported hypothermia as the underlying cause of morbidity in the surgical population with clear linkage to SSI.
Additional problems associated with hypothermia include: increased blood loss, impaired metabolism, DVT development, impaired immune system function, patient discomfort and pain, and increased mortality risk (Andrzejowski et aI., 2008; Bitner et aI., 2007; Fossum, Hays, & Henson, 2002; Kurz et aI., 1996; Mahoney & Odom, 1999; Weirich, 2008). Postoperative shivering increases metabolic rate and oxygen demand by as much as 100% to 500% placing patients with underlying cardiac disease at risk. A body temperature of 1.50 below normal triples the incidence of ventricular tachycardia and morbid cardiac events (Sessler, 1997).
Perioperative hypothermia is associated with higher treatment costs related to increased length of stay, increased morbidity and mortality, and other adverse outcomes (Backster et aI., 2007; Defina & Lincoln, 1998). Hospital length of stay in the hypothermic patient is 2.6 days longer than the normothermic patient. The cost of relatively mild hypothermia (0.5 to 1.50 below normal) can range from $2,000 to $7,000 per patient (Mahoney, 2005; Wagner, 2006).
Prewarming is the application of heat to the patient’s body prior to entry to the operative suite and provides the best defense against IPH development. Utilization of prewarming increases heat content within the peripheral compartment and decreases redistribution of heat from core to periphery (Cooper, 2006; Putzu, Casati, Berti, & Pagliarini, 2007; Wagner, Byrne, & Kolcaba, 2006b). Benefits can be derived from 30 minutes or more of prewarming providing maintenance of normothermia for up to three hours. Without prewarming, patient core temperature within the operative suite decreases quickly after anesthesia induction despite active warming. Once the redistribution phase begins increasing and maintaining core temperature becomes difficult due to the time required to re-warm the patient. This is significant for short duration surgical procedures. Prewarming also provides a method of warming patients who may be difficult to warm within the operative suite. For example, during large, open cavity surgery or procedures during which there is large body area exposure.
Traditionally, cotton blankets have been utilized to provide thermal comfort and prevent IPH within the perioperative environment, but this has been proven to be ineffective and inefficient (Cooper, 2006; Mahoney & Odom, 1999; Senn, 2002; Sessler & Schroeder, 1993; Wagner et ai., 2006b). Heat content in cotton blankets dissipates within ten minutes. This results in the need for constant replacement and ineffective patient prewarming. A more effective and efficient method is the use of forced-air warming (FAW) (Fiedler, 2001; Paulikas, 2008; Sessler & Schroeder, 1993; Weirich, 2008).
Prevention of IPH is simple, cost effective, and easily managed within the perioperative period. Strategies include preoperative warming, maintenance of normothermia during the intraoperative period, and continued monitoring and intervention in the PACU. The elimination of IPH can improve surgical outcomes, increase patient satisfaction, and assist in delivering fiscally responsible care during the perioperative episode.
All further references to temperature will reflect Celsius measurement and will omit the term “Celsius”.