Effect of Intraoperative Goal-Directed Fluid Management on Tissue Oxygen Tension in Obese Patients: a Randomized Controlled Trial

Abstract

Background: Perioperative subcutaneous tissue oxygen tension (PsqO2) is substantially reduced in obese surgical patients. Goal-directed fluid therapy optimizes cardiac performance and thus tissue perfusion and oxygen delivery. We therefore tested the hypothesis that intra- and postoperative PsqO2 is significantly reduced in obese patients undergoing standard fluid management compared to goal-directed fluid administration.

Methods: We randomly assigned 60 obese patients (BMI ≥ 30 kg/m2) undergoing laparoscopic bariatric surgery to receive either esophageal Doppler-guided goal-directed fluid management or conventional fluid treatment. Our primary outcome parameter was intra- and postoperative PsqO2 measured with a polarographic electrode in the subcutaneous tissue of the upper arm. A random effects linear regression model was used to analyze the effect of intervention.

Results: Overall, mean (± SD) PsqO2 was significantly higher in obese patients receiving goal-directed therapy compared to conventional fluid therapy (65.8 ± 28.0 mmHg vs. 53.7 ± 21.7, respectively; repeated measures design adjusted difference: 13.0 mmHg [95% CI 2.3 to 23.7; p = 0.017]). No effect was seen intraoperatively (69.6 ± 27.9 mmHg vs. 61.4 ± 28.8, difference: 9.7 mmHg [95% CI -3.8 to 23.2; p = 0.160]); however, goal-directed fluid management improved PsqO2 in the early postoperative phase (63.1 ± 27.9 mmHg vs. 48.4 ± 12.5, difference: 14.5 mmHg [95% CI 4.1 to 24.9; p = 0.006]). Intraoperative fluid requirements did not differ between the two groups.

Conclusions: Goal-directed fluid therapy improved subcutaneous tissue oxygenation in obese patients. This effect was more pronounced in the early postoperative period.

Clinical trial number and registry: The study was registered at ClinicalTrials.gov (NCT01052519).

Keywords: Goal-directed fluid therapy; Laparoscopic surgery; Obesity; Tissue oxygen tension.

Conflict of interest statement

The authors declare that they have no conflict of interest.

Figures

Fig. 1

Flow diagram of participants included in the study according to CONSORT recommendation (GDFT: goal-directed group; CG: control group)

Fig. 2

Intraoperative and postoperative subcutaneous tissue oxygen tension in patients undergoing laparoscopic gastric bypass surgery. Box plots indicate the median and interquartile range of PsqO2 values (mmHg) measured in the subcutaneous tissue of the arm (upper arm) in the two patient groups (median: bar; interquartile range: box; 10th to 90th percentile: whiskers; “+”: outliers); goal-directed group (GDFT group; gray) and conventional group (control group; white). For statistical comparisons, a random effects GLS regression model was used

Fig. 3

Secondary outcome measures. Forest plot showing interaction of potential modifiers on the main effect (coefficient: box or arrow indicating its direction; 95% confidence interval: error bars) for the intraoperative and the postoperative period. FTc, corrected flow time; SV, stroke volume; CI, cardiac index; CO, cardiac output; FiO2, inspired oxygen fraction; Et Sevoflurane, end-tidal sevoflurane concentration; Core Temp., core temperature at the distal esophagus; MAP, mean arterial pressure; TsqO2, subcutaneous tissue temperature; skin temp. gradient, forearm-fingertip skin temperature; VAS, visual analog scale