Comparison of 56 Hours versus 32 Hours of Perioperative Antibiotic Prophylaxis in Adult Cardiac Surgery

Objectives: There are several reasons why prolonged perioperative antibiotic prophylaxis (PAB) should be used in cardiac surgery, such as cardiopulmonary bypass, systemic cooling for myocardial protection, invasive devices remaining after surgery, and delayed extubation after surgery. Furthermore, there are few data on the pharmacokinetics of antibiotics during cardiopulmonary bypass. Recommendations for PAB in cardiac surgery vary, ranging from single infusion of antibiotics to durations up to 72 hours.

Methods: Between 01.01.2011 and 31.12.2011, 1096 consecutive cardiac surgery patients were assigned to one of two groups receiving PAB with a second-generation cephalosporin for either 56h (group I) or 32h (group II). Patients' characteristics, intraoperative data, and the in-hospital follow-up were analyzed. Primary endpoint was the incidence of surgical site infection (deep and superficial sternal wound-, and vein harvesting site infection; DSWI/SSWI/VHSI). Secondary endpoints were the incidence of respiratory-, and urinary tract infection, as well as the mortality rate.

Results: 615/1096 patients (56,1%) were enrolled (group I: n = 283 versus group II: n = 332). There were no significant differences with regard to patient characteristics, comorbidities, and procedure-related variables. No statistically significant differences were demonstrated concerning primary and secondary endpoints. The incidence of DSWI/SSWI/VHSI were 4/283 (1,4%), 5/283 (1,7%), and 1/283 (0,3%) in group I versus 6/332 (1,8%), 9/332 (2,7%), and 3/332 (0,9%) in group II (p = 0,76/0,59/0,63). In univariate analyses female gender, age, peripheral arterial obstructive disease, operating-time, ICU-duration, transfusion, and respiratory insufficiency were determinants for nosocomial infections (all ≤ 0,05). Subgroup analyses of these high-risk patients did not show any differences between the two regimes (all ≥ 0,05).

Risk factors	Group I (56h)	Group II (32h)	p-value
Female	23,5%	22,3%	0,82
Age > 80 years	23,7%	23,7%	1,00
PAOD	16,9%	25,3%	0,20
Operating time 240 minute	22,8%	20,3%	0,63
ICU duration < 3 days	20,5%	21,0%	1,00
Transfusion of > 5 RBC	26,5%	29,6%	0,91
Respiratory insufficiency	62,5%	66,7%	1,00

[Subgroup analyses].

Conclusions: Reducing the duration of PAB from 56h to 32h in adult cardiac surgery patients was not associated with an increase of nosocomial infection rate.