Central venous thrombosis and thrombophilia in cystic fibrosis: A prospective study.

BACKGROUND AND AIMS: Catheter venous thrombosis may result in life-threatening embolic complications. Recently, a thrombophilic tendency was described in cystic fibrosis (CF), the significance of which remains unclear. The aims of this study were to (1) document the frequency of catheter venous thrombosis detected by colour-Doppler-ultrasound (Doppler-US), (2) assess genetic and acquired thrombophilia risk factors for catheter venous thrombosis and hypercoagulability status and (3) provide recommendations on laboratory screening when considering insertion of a totally implantable vascular access device (TIVAD) in CF patients. METHODS: We designed a multicentre prospective study in patients selected at the time of catheter insertion. Doppler-US was scheduled at 1 and 6months after insertion and before insertion in case of a previous central line. Blood samplings were drawn at insertion and at 1 and 6months later. RESULTS: One-hundred patients received a TIVAD and 90 completed the 6-month study. Prevalence of thrombophilia abnormalities and hypercoagulability was found in 50% of the cohorts. Conversely, catheter venous thrombosis frequency was low (6.6%). CONCLUSION: Our data do not support biological screening at the time of a TIVAD insertion. We emphasise the contribution of a medical history of venous thromboembolism and prospective Doppler-US for identifying asymptomatic catheter venous thrombosis to select patients who may benefit from biological screening and possible anticoagulant therapy.

Influence of DNA on the activities and inhibition of neutrophil serine proteases in cystic fibrosis sputum.

Uncontrolled proteolysis by neutrophil serine proteases (NSPs) in lung secretions is a hallmark of cystic fibrosis (CF). We have shown that the active neutrophil elastase, protease 3, and cathepsin G in CF sputum resist inhibition in part by exogenous protease inhibitors. This resistance may be due to their binding to neutrophil extracellular traps (NETs) secreted by the activated neutrophils in CF sputum and to genomic DNA released from senescent and dead neutrophils. Treating CF sputum with DNase dramatically increases its elastase activity, which can then be stoichiometrically inhibited by exogenous elastase inhibitors. However, DNase treatment does not increase the activities of protease 3 and cathepsin G, indicating their different distribution and/or binding in CF sputum. Purified blood neutrophils secrete NETs when stimulated by the opportunistic CF bacteria Pseudomonas aeruginosa and Staphylococcus aureus. The activities of the three proteases were unchanged in these conditions, but subsequent DNase treatment produced a dramatic increase in all three proteolytic activities. Neutrophils activated with a calcium ionophore did not secrete NETs but released huge amounts of active proteases whose activities were not modified by DNase. We conclude that NETs are reservoirs of active proteases that protect them from inhibition and maintain them in a rapidly mobilizable status. Combining the effects of protease inhibitors with that of DNA-degrading agents could counter the deleterious proteolytic effects of NSPs in CF lung secretions.

Value of the chlorhexidine decontamination method for recovery of nontuberculous mycobacteria from sputum samples of patients with cystic fibrosis.

The chlorhexidine method was compared to the N-acetyl-l-cysteine-NaOH-oxalic acid decontamination method currently recommended for the recovery of nontuberculous mycobacteria (NTM) from patients with cystic fibrosis. Sputum samples (n = 827) treated with chlorhexidine yielded twice as many NTM-positive cultures as those treated by the reference method (54 [6.50%] versus 27 [3.25%]; P < 0.0001) despite a higher contamination rate (20% versus 14.2%; P = 0.0017).