Intra-operative drug level monitoring of pre-operative antibiotic for surgical prophylaxis in the patients of elective spinal surgery.

Objectives: Single dose prophylaxis is good enough for general surgery with low risk patients. However, the evidence for the effectiveness of single dose anti-microbial prophylaxis (AMP) is not conclusive in high risk patients and spinal surgeries requiring instrumentation or the use of implants in particular. No studies have explored the various concentration of ceftriaxone in plasma and tissue as well during an ongoing spinal surgery. Therefore, the objective of study was to correlate the serum and tissue concentrations of ceftriaxone with the SSI and identify patients with increased risk of SSI.

Methods: It was an open label prospective study in 50 consecutive patients who underwent elective spine surgery under prophylactic cover of ceftriaxone. Serum and tissue concentration were estimated by high pressure liquid chromatography during the ongoing surgery.

Results: Subjects were observed for any post-operative complications including SSI. Serum (p=0.002) and tissue (p=0.012) concentrations of ceftriaxone at the closure of spinal surgery were associated with SSI. Duration of the surgery (p=0.04) and use of implants (p=0.02) were also important surgery related risk factors.

Conclusions: Serum and tissue concentrations of ceftriaxone at the closure and duration of surgery and instrumentation or use of implants in the spinal surgery are good predictors of SSI.