Perioperative inflammatory response in total knee arthroplasty patients: impact of limb preconditioning.

BACKGROUND AND OBJECTIVES: Ischemic preconditioning of tissue that is to undergo procedure-induced underperfusion has been used in a number of surgical settings to reduce the subsequent inflammatory response and its sequelae. The objective of this prospective, randomized study was to evaluate the effect of ischemic preconditioning on the systemic inflammatory response, degree of lung catabolism, and postoperative-pain associated with total knee arthroplasty (TKA). MATERIALS: Thirty-four patients undergoing unilateral TKA under tourniquet ischemia were enrolled with half (n = 17) being randomized to an episode of limb preconditioning before induction of ischemia for surgery. Markers of inflammation (interleukin 6 [IL-6], C-reactive protein,tumor necrosis factor >, and leukocyte count) and elastin catabolism(desmosine) were measured at baseline and various points postoperatively.Pain scores and length of stay were recorded. RESULTS: A significant increase in the levels of IL-6, C-reactive protein,tumor necrosis factor >, and white blood cell count was observed after surgery in both groups. Despite trends toward decrease in the IL-6 level in the preconditioning group, no significant difference between groups was observed for all markers at any given time point. Urine desmosine-creatinine-ratios did not differ between groups, and no significant-changes from baseline were seen postoperatively. However, median pain scores and length of hospital stay were lower in the treatment group. CONCLUSIONS: Preconditioning of the lower extremity in the setting of TKA under regional anesthesia may have limited value in reducing the systemic inflammatory response and level of lung injury. However, preconditioning may be associated with beneficial effects such as reduction in postoperative pain levels, and thus, further investigations are warranted.

Correlation between centrally versus peripherally transduced venous pressure in prone patients undergoing posterior spine surgery.

STUDY DESIGN: Prospective clinical observational study. OBJECTIVE: To evaluate the correlation and agreement between peripherally and centrally transduced venous pressures in prone spine surgery patients. SUMMARY OF BACKGROUND DATA: In view of a variety of potential complications associated with the placement of central venous lines for the purpose of central venous pressure (CVP) monitoring, a number of authors have suggested that the use of peripherally transduced pressures (PVP) instead may yield similar results. Data confirming the validity of this technique for the purpose of intravascular fluid volume monitoring in prone patients undergoing spine surgery remain scarce. METHODS: After protocol approval by the internal review board, we enrolled 40 patients who underwent spine surgery in the prone position. CVP and PVP were recorded simultaneously. The data pairs were analyzed for correlation. Bland and Altman plots were created to evaluate the degree of agreement between the 2 modes of venous pressure monitoring. RESULTS: A total of 1275 data pairs were collected. The mean PVP was 17.55 mm Hg +/- 4.93 mm Hg and the mean CVP 15.52 mm Hg +/- 4.77 mm Hg (P < 0.001), thus yielding a mean difference of 2.04 mm Hg +/- 1.39 mm Hg. PVP and CVP correlated well over a wide range of pressures (r = 0.949, r = 0.920 [P < 0.001]). A high level of agreement was found between both methods of venous pressure measurement. CONCLUSION: CVP and PVP correlate well under conditions associated with prone spine surgery. With a high level of agreement found in this study, PVP may represent an attractive alternative to CVP monitoring to assess fluid volume trends intraoperatively.