Hemodynamic changes during a combined psoas compartment-sciatic nerve block for elective orthopedic surgery.

BACKGROUND

Hemodynamic variables can theoretically be influenced by a combined psoas compartment-sciatic nerve block (CPCSNB) owing to a relatively high systemic absorption of local anesthetics and extended vasodilatation in the anesthetized limb (hemisympatectomy). In this study we assessed and documented hemodynamic changes during CPCSNB for elective orthopedic surgery.

METHODS

Twenty consecutive patients scheduled for a total hip arthroplasty revision surgery were subjected to a CPCSNB with 150 mg bupivacaine (with epinephrine 1:200.000) 90 minutes before surgery (2 separate single-injection blocks: 30 mg bupivacaine for the sciatic nerve block and 120 mg bupivacaine for the psoas compartment block). Cardiac index, invasive arterial blood pressure, and heart rate were measured at baseline and 60 minutes after puncture using a minimally invasive cardiac output monitoring device (FloTrac/Vigileo™ system (Edwards Lifesciences, Irvine, CA)).

RESULTS

Cardiac index did not change after a CPCSNB (preblock cardiac index 2.98 ± 0.54 l · min(-1) · m(-2) versus postblock cardiac index 2.99 ± 0.60 l · min(-1) · m(-2)). There was a significant reduction in mean arterial blood pressure (108 ± 16 mm|Hg vs. 99 ± 16 mm|Hg (P < 0.001)) and diastolic blood pressure (75 ± 9 mm|Hg vs. 68 ± 10 mm|Hg (P = 0.001)). Heart rate increased significantly (68 ± 9 beats · min(-1) vs. 73 ± 10 beats · min(-1) (P = 0.001)).

CONCLUSION

CPCSNB did not affect cardiac index. Changes in arterial blood pressure and heart rate, although statistically significant, remained within an acceptable clinical range (<10% variation). CPCSNB does not appear to induce clinically significant hemodynamic changes in this group of patients.