Maintaining patient normothermia pre-, peri- and post-operatively is a critical element of preventing surgical site infections and other complications such as metabolic acidosis, cardiovascular effects, increased respiratory distress and surgical bleeding.
According to the Guideline Statement for the Maintenance of Normothermia in the Perioperative Patient from the Association of Surgical Technologists (AST), “Measures to monitor and maintain body temperature should begin in the pre-operative phase and continue into the postoperative phase of the surgical procedure. The monitoring of patient temperature is the responsibility of all surgical team members and not just the anesthesia provider. Maintaining normothermia in the perioperative patient is a collaborative effort between the anesthesia provider, the surgeon, perioperative personnel and perianesthesia personnel.”
The American Society of PeriAnesthesia Nurses (ASPAN)’s Evidence-Based Clinical Practice Guideline for the Promotion of Perioperative Normothermia states, “Perioperative hypothermia, defined as a core temperature below 36 degrees C, has adverse effects that range from patient thermal discomfort to increased morbidity and mortality. Even mild intraoperative hypothermia, a core temperature of 34 degrees C to 36 degrees C, has adverse consequences that are well documented ... The prevention of unplanned perioperative hypothermia and promotion of normothermia remains a national priority in the prevention of surgical site infection, and has been designated as a quality measure by the Surgical Care Improvement Project (SCIP).”
According to the AST guideline, perioperative temperature management is imperative to positive surgical outcomes. The body maintains its temperature between 36 degrees C and 38 degrees C by balancing heat production and heat loss. It is imperative for the surgical team to remember that the body loses heat through radiation (from tissues), conduction (contact with cool surfaces), evaporation (respiration) and convection (exposure to the environment).
The challenge lies in effective body temperature measurement and monitoring. According to the ASPAN guideline, “Although the measurement of core temperature (e.g., pulmonary artery, distal esophagus, nasopharynx, tympanic membrane [via thermistor]) is the best indicator of thermal status, core temperatures are frequently not feasible and unrealistic during the perianesthesia period. Skin temperature, easily obtained during the perioperative period, is a function of external influences and thermoregulatory function of the body. Clinically available ‘near-core’ measures (e.g., oral, bladder, rectal, temporal artery, tympanic membrane [via infrared sensor], axilla) must be relied on to evaluate thermal balance across much of the perianesthesia/perioperative period. Unfortunately, each near-core measure has limitations in the ability to reflect core temperature.” ASPAN acknowledges in its guideline that “the research on perianesthesia temperature measurement is weak due to a lack of controls, insufficient statistical analysis, and lack of replication,” but makes the following recommendations on temperature measurement: Near-core measures of oral temperature best approximates core; the same route of temperature measurement should be used throughout the perianesthesia period for comparison purposes; and caution should be taken in interpreting extreme values (e.g., 35 degrees C) from any site with near-core instruments.
