name="Table 2" id="Table 2" target="_self">Table 2. Comparison of outcomes between high anxiety and low/moderate anxiety groups.

Table 3. Factors associated with intraoperative hypothermia (adjusted and unadjusted analyses).

that occurs when anesthesia inhibits tonic thermoregulatory vasoconstriction [3]. The second phase is a result of heat loss exceeding metabolic heat production, which reduces core temperature in a slow, linear fashion [17]. Finally, a core temperature plateau is reached when emergence of thermoregulatory vasoconstriction decreases cutaneous heat loss [18] and constrains metabolic heat in the core thermal compartment [19]. The extent to which redistribution decreases core temperature depends on the anesthetic-induced inhibition of tonic thermoregulatory vasoconstriction and the magnitude of the core-to-peripheral tissue temperature gradient. The core thermal compartment represents about half of the body mass, and the remaining mass is typically 2˚C - 4˚C cooler than the core [20]. Preoperative anxiety increases the patient’s catecholamine secretion, and the increased catecholamine level causes tachycardia, hypertension, and arrhythmia [21]. Cutaneous vasoconstriction is controlled by the sympathetic nervous system, via norepinephrine binding to alpha-1 receptors [22]. In the present study, increased peripheral blood flow variability was observed in patients with a high level of anxiety. The mean body temperature of the peripheral compartment therefore has a major effect on the change in core temperature due to the coreto-peripheral redistribution of temperature, and the preoperative anxiety level may predict the degree of hypothermia. Once redistribution has occurred, heat that has been distributed to the peripheral tissues cannot be recovered by the core, because heat cannot move up a temperature gradient. Relative hypothermia in patients with a high anxiety level therefore persisted during the early phase of general anesthesia. Although high anxiety level and peripheral blood flow variability were significant predictors of core hypothermia during combined epidural and general anesthesia, other variables [12] such as gender, age, BMI, BSA, ASA physical status, HR variability, SBP variability, history of cardiovascular disease, and diabetes mellitus were not predictors of change in core temperature. It is possible that the effects of age, BMI, BSA, and ASA physical status were underestimated in the current study because the range of these variables may not have been wide enough to show an effect. Intense vasodilation associated with combined epidural and general anesthesia may have resulted in rapid and significant heat loss, causing hypothermia regardless of the other factors (age, BMI, BSA, ASA physical status, HR variability, SBP variability, history of cardiovascular disease, and diabetes mellitus).

Previous studies did not evaluate the association between anxiety level and the risk of hypothermia in the clinical setting, even though it is known that thermoregulation is inhibited by anesthesia, causing redistribution of body heat between the core and the periphery [3]. Admission to hospital, particularly when undergoing surgical treatment, may be emotionally distressing [23]. The importance of giving patients information has been supported by numerous studies [24,25]. These studies demonstrated that patients who are psychologically prepared for surgery have better outcomes than those who are not adequately prepared. Redistribution of body heat between the peripheral and core compartments seems to be completed within 1 hour after the induction of general anesthesia [26]. It is therefore important for nurses to ensure that patients are physically and psychologically as well prepared for surgery as possible. Further studies are needed to evaluate nursing interventions that might prevent hypothermia during general anesthesia.

The primary limitation of this study is that the findings cannot be generalized, as only patients who underwent elective major abdominal surgery under combined epidural and general anesthesia were studied. It is not clear whether these findings are clinically relevant to patients undergoing different types of surgery, such as open thoracic or urgent surgery.

5. Conclusion

The relationship between preoperative anxiety level and intraoperative hypothermia (<36˚C) was investigated. The STAI was used to measure the anxiety level and the relation was examined with descriptive and multivariate risk analysis. High anxiety level was found in 61 patients (51%), of which 26 (43%) developed hypothermia during the first hour and 40 (66%) developed hypothermia during the first 2 hours of anesthesia. After adjustment for covariates, patients with a high anxiety level were found to have a 2.17-fold higher risk of hypothermia during the first hour and a 1.77-fold higher risk of hypothermia during the first 2 hours than patients with a low/moderate anxiety level. The risk of hypothermia in the early phase of general anesthesia can be predicted by measurement of the preoperative anxiety level using the STAI.

6. Relevance to Clinical Practice

The findings of this study suggest that a high preoperative anxiety level is significantly associated with intraoperative hypothermia. It is therefore important for nurses to identify patients with a high anxiety level and spend more time with them. In addition, nurses should implement a preventive care program that includes anxiety management and thermal care. Nurses have a duty to ensure that patients admitted to hospital are as physically and psychologically prepared for surgery as possible. This can be achieved by using appropriate tools to assess anxiety, and by spending time listening to patients’ concerns. Working in partnership with patients is essential for achieving good outcomes.

7. Acknowledgements

We thank our nursing colleagues in the operating room for their help with data collection.

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NOTES

*The authors report no conflicts of interest.

#Corresponding author.

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