Optimizing stroke volume and oxygen delivery in elective abdominal aortic surgery

Introduction

Patients undergoing elective abdominal aortic surgery (EAAS) are at risk of developing complications due to preoperative co-morbidity, surgical trauma, blood loss and inflammatory injury [1]. Individualized goal-directed therapy (IGDT) has been proposed to improve outcome in patients undergoing high-risk surgery [2]. The aim of this study was to investigate whether IGDT, targeting stroke volume (SV) and oxygen delivery (DO₂), can be performed safely in EAAS.

Methods

Sixty-three EAAS patients were randomized to IGDT or conventional therapy. The LiDCO™plus system was used for SV and DO₂ monitoring. SV was optimized by 250 ml fluid challenges intraoperatively and the first 6 hours postoperatively. DO₂ was optimized 6 hours postoperatively targeting a DO₂I level of 600 ml/min/m², by infusion of dobutamine, if necessary. Hemodynamic data were collected at baseline (t0) preoperatively (t1), before aortic cross-clamping (t2), at the end of surgery (t3), and the first 6 hours postoperatively (p1 to p6). All patients were monitored with five-lead ECG during dobutamine infusion and dosage was reduced at signs of ischemia or heart rate >20% above baseline. Dobutamine dosage was limited to a maximum of 10 μg/kg/minute.

Results

The mean SVI level was 19.4% higher at p4 to p6 in the IGDT group compared with the control group (P = 0.02), and 12.1% higher in the entire intervention period (t1 to p6) (P = 0.07). The mean DO₂I was 18.0% higher at p4 to p6 (P = 0.01) and 12.9% higher in the entire intervention period (t1 to p6) in the IGDT group (P = 0.03). Mean arterial pressure and heart rate did not differ significantly (P = 0.12 and P = 0.21). There was no difference in the frequency of postoperative cardiac complications between the groups.

Conclusions

The results of this study demonstrate that IGDT targeting SV and DO₂ can be performed safely in patients undergoing EAAS. Whether this intervention is beneficial is being evaluated in the current study.