Abstract

RRA-4

Adequacy of a single dose of vancomycin for antimicrobial prophylaxis for posterior spinal fusion surgery for adolescent idiopathic scoliosis

¹Joseph P, ²Gangadharan M, ³Chau D, ²Bhandari A, ²Koska A, ¹Comstock C, ¹Weisman K
¹Driscoll Childrens Hospital, Corpus Christi, TX, USA; ²UTMB, Galveston, TX, USA; ³Eastern Virginia Medical School, Norfolk, Virginia, USA

1 .Introduction: Surgical site infection (SSI) is a serious complication of spinal surgery for adolescent scoliosis (AIS). Antimicrobial prophylaxis is a cornerstone of SSI prevention. Vancomycin (vanc) is used at this institute due to a high prevalence of MRSA (MIC – 2mcg/ml). No guidelines exist to re-dose vanc intraoperatively in children. 1 As per the latest WHO guidelines, low tissue antibiotic concentrations at wound closure is associated with higher rates of SSI. 2. A consensus statement by the Infectious Diseases Society of America recommends maintaining vanc levels above 10 mcg/ml to prevent antibiotic resistance.3
2. Aims: To determine if (i) a single dose of intravenous vanc (15mg/kg) results in adequate serum levels for the duration of surgery (ii) the vanc concentration achieved in the vertebral pedicle is the same as in peripheral blood.
3. Methods: A prospective observational study. Fifteen consecutive patients were enrolled after IRB approval. Vanc (15mg/kg) was administered intravenously preoperatively, Peripheral blood samples were collected at three times during surgery and two samples were collected from the first and the last vertebral pedicles in which screws were placed. The volume of fluid administered, urine output and estimated blood loss were recorded.
Results:
• 13/15 (87%) Lowest vanc level during surgery was less than 10mcg/ml
• 3/15 (20%) Lowest vanc level was less than 5 mcg/ml
• The concentration of vanc achieved at the vertebral pedicle was the same as in peripheral blood.
5. Limitations:
a. Resources limited the study to five samples per patient
6. Conclusion:
The authors propose that a second dose of vanc be administered after 6 hrs in patients with normal renal function, if surgery is still in progress, to maintain adequate levels till skin closure.

References
1. Rybak M etal .Therapeutic monitoring of vancomycin in adult patients: A consensus review of the American Society of Health-System Pharmacists ….Am J Health-Syst Pharm. 2009; 66:82-98
2.Global Guidelines for the Prevention of Surgical Site Infection Geneva:World health organisation; 2016.ISBN-13: 978-92-4-154988-2
3.Bratzler D etal .Clinical practice guidelines for antimicrobial prophylaxis in surgery. Am J of Health Syst Pharm February 2013; 70 (3) 195-283