Graduation Year

2007

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Nursing

Major Professor

Maureen Groer, Ph.D.

Keywords

Hypothermia, Forced-air warming, Catecholamine, Cytokine, Innate immunity

Abstract

When a patient is exposed surgical stress, the endocrine system secretes hormones in response to that stress. These hormones further activate the immune system to release cytokines and other acute phase reactions. These processes are supposed to protect the body by upregulating the innate immune system and producing an inflammatory response that acts to protect and heal. However, uncontrolled surgical stress may cause a weaker immune response that may lead to delayed wound healing. The phenomenon of unplanned perioperative hypothermia is known to expose patients to additional surgical stress. The purpose of this preliminary experimental study was to determine the effect of a preoperative warming intervention on the acute phase response of surgical stress in surgical patients.

Specifically, the aim of this study was to evaluate the effect of a prewarming intervention using a forced-air warming (FAW) device versus routine care (RC) using warmed cotton blankets on the development of unplanned hypothermia, cytokine production, and endocrine responses. It was hypothesized that 1) the FAW participants would experience less unplanned perioperative hypothermia than the RC participants; 2) the FAW participants would experience lower catecholamine and cortisol levels than the RC participants; and 3) the FAW participants would experience higher proinflammatory cytokine and CRP production intra- and postoperatively than the RC participants. Infrared tympanic temperatures and 4 blood samples were taken at 4 time intervals from each of the 28 (n = 14 each group) randomized participants that underwent routine general anesthesia surgery.

Serum concentrations of CRP, cortisol and IL-1beta, IL- 6, TNF-alpha, and IFN-gamma, and plasma concentrations of epinephrine and norepinephrine were measured. To test the hypotheses across time and between groups, a repeated measures ANOVA design was used. Though FAW was not associated with a differential endocrine or inflammatory response in this small, preliminary study, further study of forced air warming as a preoperative nursing intervention is warranted. The finding of higher than expected IL-6 levels in the preoperative period suggests a potential role for anxiety, an important factor in psychoneuroimmunological pathways, that could affect recovery and healing. The relationship between surgical stress, anxiety, and preoperative IL-6 deserves further study.

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