The Effect of Preoperative Active Warming on Intraoperative Body Temperature

A randomized controlled study was conducted to examine the effect of active warming before total knee arthroplasty on intraoperative body temperature and comfort.

Inadvertent perioperative hypothermia is defined as a patient's internal temperature below 36 °C in surgical settings. All patients undergoing surgery and other invasive procedures are at risk of developing undesirable hypothermia. Both general and neuraxial anesthesia greatly impair thermoregulatory control, and as a result, unwarmed surgical patients become hypothermic. General and regional anesthesia causes undesirable hypothermia as a result of the redistribution of body temperature from the center to the periphery.

In the perioperative period, patients over 60 years of age with poor nutritional status, low core temperature before surgery, preoperative fasting and fluid deprivation before anesthesia, premedication, type of surgery, dry and cold anesthetic gases, cold intravenous fluids, flushes, blood products (cold fluids direct core temperature) Hypothermia is caused by low ambient temperature, wet skin, dressings or sheets, anesthetic agents, large open cavity or abdominal surgery, excessive blood loss, drugs used before surgery.

There are many methods to maintain the body temperature of patients (passive isolation methods) or to warm the patient (active warming methods). Passive insulation methods include heated cotton blankets, surgical drapes, and thermal suits. Active heating techniques include compressed air heaters, electric heating blankets, and heated liquids and gases.

In the literature, studies on active and passive heating methods have been found in order to prevent undesirable hypothermia. There are studies with stand-alone active heating methods (such as pressurized hot air blowing systems, heated liquids, circulating hot water systems) and combined methods. Because the results of these studies were different, a randomized controlled study was planned to investigate the effectiveness of the prewarming intervention, to support the surgical process nurses in clinical practice, and to increase the reliability of the results, before developing a procedure related to prewarming.

In the study, the effect of prewarming with a hot air blowing system before the surgical procedure on the patients who will undergo total knee arthroplasty, on the patient's body temperature during the operation and on the comfort in the early postoperative period will be determined.

Eligibility Criteria:
Inclusion Criteria:

* Patients who volunteered to participate in the study
* Elective surgery planned
* Patients between the ages of 18-80
* ASA I-III
* Neuroaxial anesthesia applied
* No sensory problems (hearing, vision)
* No psychiatric illness
* 18.5\<BMI\<39.9 kg/m2

Exclusion Criteria:

* Body temperature \<36°C at the entrance to the operating room
* Preoperative body temperature \<36°C
* Patients who develop complications during preheating (blood pressure rise, patients are uncomfortable with the heat, they are agitated)
* Peripheral vascular disease
* Patients with communication difficulties
* Patients with infectious disease