Postoperative Wound Healing: Hydration and Oxygenation
Name: Brenda Mygrant
Rank: LTC, USA
Organization: Henry M. Jackson Foundation
Performance Site: Madigan Army Medical Center, Tacoma, WA
Year Published: 1994
Abstract Status: Initial
Tissue wounding may result from surgery or accidental trauma and convalescence may be slowed by complications. Delayed wound healing and wound infection result in prolonged hospital stay, increased health care costs, and contribute to morbidity and mortality. While many factors are important for wound healing and resistance to wound infection, tissue blood flow and oxygen levels are critical. However, therapies to improve tissue perfusion and oxygenation have not been fully developed or tested. Postoperative hypovolemia is a common contributor to tissue hypoxia with resultant reductions in tissue oxygen levels. Patients undergoing cardiac surgery are especially vulnerable to fluid replacement quandaries because of the clinical dilemma existing between the strain of circulatory overload and suitable tissue hydration needed to promote tissue healing and resistance to wound infection. The specific aims of this study are (1) to compare the effects of augmented postoperative fluid replacement and conventional fluid replacement on subcutaneous tissue oxygen (PscO2), subcutaneous tissue perfusion, and cellular markers of wound healing; and (2) to determine the relationships between a) subcutaneous tissue oxygen levels and wound healing indicators; and b) the incidence of wound complications/infection. Using a randomized, two group quasi-experimental repeated measures design, subjects scheduled for cardiac surgery will receive either augmented (n = 81) or conventional (n = 81) fluid replacement postoperatively. PscO2 and perfusion will be measured on the 8th, 20th, and 36th postoperative hours with an optode tonometer system. Wound healing will be evaluated by analysis of tissue cellularity and hydroxyproline from a tissue sample obtained from a small, polytetrafluorethylene tube placed subcutaneously and removed on the 7th postoperative day. Wound complications/infections will be evaluated using the ASEPSIS scoring method. Differences between groups on tissue oxygen, perfusion, and wound healing variables will be tested with Student's t test, Chi-Square, ANOVA for repeated measures, or the Mann Whitney U test. Relationships will be tested with Pearson's product moment correlation coefficients. Determining fluid replacement levels that support tissue oxygen, blood flow, and healing without increasing added stress on the heart have a long range of consequences of promoting cost-effective care and sustaining a healthy military force, in both times of war and peace.