Early prediction of capillary leak syndrome in infants after cardiopulmonary bypass.

Objectives: As an inflammatory reaction after cardiac surgery involving cardiopulmonary bypass (CPB), capillary leak syndrome (CLS) is associated with increased morbidity, especially in newborns and infants. We investigated whether different cytokines measured via microdialysis can monitor local inflammation in adipose tissue subcutaneously and predict the development of CLS early, before clinical signs appear. Furthermore, we investigated whether there are age-related differences between the inflammatory responses in newborns and infants.

Methods: We performed a prospective study taking serial measurements of the inflammatory response detected in subcutaneous adipose tissue up to 24 h postoperatively. The cohort consisted of 23 neonates and infants (median age 155, range 6-352 days; median body weight 5.4 kg, range 2.6-9.2 kg) who underwent congenital heart surgery with CPB. Microdialysis catheters were introduced in one lateral thigh subcutaneously using a velocity of 1.0 µl/min. Serial microdialysis analyses for cytokines (interleukin [IL]-6, IL-8, IL-10) and complement activation (C3a) were performed. CLS was quantified by X-ray subcutaneous-thoracic ratios.

Results: The median bypass time was 150 min (range 42-432 min) and the aortic cross-clamp time 76 min (range 0-188 min). Six out of 23 infants developed postoperative CLS. Younger age (P = 0.02) and longer bypass time (r = 0.48; P = 0.021) correlated strongly with the development of CLS. Pro- and anti-inflammatory cytokines and complement activation were detected subcutaneously in all patients. The highest levels of IL-6 (55.0 pg/ml) and IL-8 (65.9 pg/ml) were detected 2 h after CPB. During surgery, the C3a level rose dramatically (167.1 ng/ml), followed by a release of IL-10 at the end of CPB. Patients with CLS produced a characteristic and significant second peak of C3a at 8 h postoperatively (CLS 63.8 ng/ml vs non-CLS 23.5 ng/ml; P < 0.01). We detected an aged-related difference in the release of IL-6 and C3a. Longer intubation time (r = 0.63; P = 0.001), higher inotropic demand (r = 0.67; P = 0.001) and higher serological lactate levels (r = 0.65; P = 0.001) correlated closely with the development of CLS.

Conclusion: Diagnostic microdialysis can detect local inflammation and may predict the development of CLS early before severe clinical signs appear.