Department of Intensive Care Medicine, Maastricht University Medical Centre and Maastricht University, Maastricht, The Netherlands.
Eur J Cardiothorac Surg. 2011 Aug;40(2):372-8. doi: 10.1016/j.ejcts.2010.11.063. Epub 2011 Jan 17.
Postoperative infections due to cardiopulmonary bypass (CPB) are associated with high morbidity and mortality. The value of positive cultures taken from CPB priming fluid and CPB blood samples, however, is unclear. This study investigates the epidemiology of positive cultures from CPB and their relation to the occurrence of postoperative infection.
The study was conducted at the Maastricht University Medical Centre, a 715-bed teaching hospital with 900-1000 surgeries requiring CPB annually. From 1 January 1998 until 31 March 2010, all patients with positive CPB cultures drawn either from priming fluid or blood were retrospectively studied. Second, 335 patients with a positive CPB culture were compared with 335 randomly assigned patients who underwent cardiovascular surgery using CPB and had negative CPB cultures. Patients with active endocarditis were excluded. Demographic data and perioperative parameters were documented. Outcome measures were: a relevant infection (acute infectious valve endocarditis, wound infection, intravascular catheter-related infection, and bloodstream infection), occurrence of fever of unknown origin, and 30-day mortality.
A total of 21840 cultures were analyzed, half being priming fluid and half CPB blood cultures. As many as 111 out of 10920 (1.0%) priming fluid cultures and 598 out of 10920 (5.6%) blood cultures tested positive. Gram-positive cocci predominated both priming fluid and blood cultures. Relevant postoperative infections within 30 days after surgery were seen in 47/663 (7.1%) of patients overall, in 27/330 in the CPB-culture-positive group (8.2%) and 20/333 in the CPB-culture-negative group (6.0%), p=0.275. As many as 38 out of 363 patients (5.7%) were affected by fever of unknown origin (CPB-culture-positive group 4.5%, and CPB-culture-negative 6.9%; p=0.191). The 30-day mortality was 16/330 (4.8%) in the CPB-culture-positive group and 13/333 (3.9%) in the CPB-culture-negative group (p=0.552).
Positive cultures from both CPB priming fluid and CPB blood samples were not a rarity and mainly involved skin bacteria, arguing that contamination may have played a role. The risk of postoperative infection within 30 days after surgery was not increased in CPB-culture-positive patients. Therefore, no evidence was found to support routine culturing of CPB samples in patients undergoing cardiothoracic surgery.
体外循环（CPB）术后感染与高发病率和死亡率相关。然而，从 CPB 预充液和 CPB 血样本中获取的阳性培养物的价值尚不清楚。本研究调查了 CPB 阳性培养物的流行病学及其与术后感染发生的关系。
该研究在马斯特里赫特大学医学中心进行，这是一家拥有 715 张床位的教学医院，每年有 900-1000 例需要 CPB 的手术。从 1998 年 1 月 1 日至 2010 年 3 月 31 日，回顾性研究了所有从预充液或血液中获得 CPB 阳性培养物的患者。其次，将 335 例 CPB 培养阳性的患者与 335 例随机分配接受 CPB 心血管手术且 CPB 培养阴性的患者进行比较。排除患有活动性心内膜炎的患者。记录人口统计学数据和围手术期参数。观察指标为：相关感染（急性感染性心内膜炎、伤口感染、血管内导管相关感染和血流感染）、不明原因发热的发生和 30 天死亡率。
共分析了 21840 个培养物，其中一半为预充液培养物，另一半为 CPB 血培养物。10920 个预充液培养物中有 111 个（1.0%）和 10920 个血液培养物中有 598 个（5.6%）呈阳性。革兰阳性球菌在预充液和血液培养物中均占优势。术后 30 天内出现相关术后感染的患者总体为 47/663（7.1%），CPB 培养阳性组为 27/330（8.2%），CPB 培养阴性组为 20/333（6.0%），p=0.275。38 例（5.7%）患者出现不明原因发热（CPB 培养阳性组 4.5%，CPB 培养阴性组 6.9%；p=0.191）。CPB 培养阳性组 30 天死亡率为 16/330（4.8%），CPB 培养阴性组为 13/333（3.9%），p=0.552。
CPB 预充液和 CPB 血样本的阳性培养物并不罕见，主要涉及皮肤细菌，这表明可能存在污染。CPB 培养阳性患者术后 30 天内发生感染的风险并未增加。因此，没有证据支持对接受心胸外科手术的患者常规进行 CPB 样本培养。
