A prospective observational study of the change in systemic ionised calcium following 4% citrate locking of venous haemodialysis catheters in intensive care patients.

Traditionally heparin has been the anticoagulant of choice for venous dialysis catheter locking. There is systemic leakage of heparin catheter locking solutions at the time of injection. Alternative agents, such as citrate, are increasingly being used. We are not aware of any data in the critical care literature on the effect of citrate locking of venous dialysis catheters on systemic ionised calcium (iCa2+). To assess the effect of 4% citrate locking of venous dialysis catheters on systemic iCa2+ in intensive care patients we performed a prospective observational study of 50 paired samples in 26 intensive care patients receiving 4% citrate dialysis catheter locking in an adult tertiary intensive care unit between May 2016 and December 2016. Arterial blood gas (ABG) analysis was performed prior to venous dialysis catheter locking and a baseline iCa2+ result obtained. The catheter was locked with 4% citrate solution. A further ABG was sampled between 30 and 120 seconds later and the iCa2+ results were compared. Patients were observed for clinical signs of hypocalcaemia. On average, there was little difference between the pre- and post-catheter locking iCa2+ (median pre-locking iCa2+ 1.19 mmol/l, mean change of +0.004 mmol/l, 95% confidence interval [CI] -0.004 to 0.013, P=0.34). There was no evidence this difference differed by length of catheter P=0.26) or site of catheter P=0.85) insertion, but there was some evidence that this differed by receipt of citrate dialysis circuit anticoagulation P=0.013). Patients who received citrate dialysis circuit anticoagulation had an increase in catheter locking iCa2+ by 0.017 mmol/l (95% CI 0.00 to 0.028). Locking of venous dialysis catheters with 4% citrate solution has no clinically significant effect on systemic iCa2+ in intensive care patients with indwelling venous dialysis catheters.

Systemic anticoagulation related to heparin locking of non-tunnelled venous dialysis catheters in intensive care patients.

Heparin locking of venous dialysis catheters is routinely performed in intensive care to maintain catheter patency when the catheters are not being used. Leakage of heparin into the circulation can potentially cause systemic anticoagulation and may present a risk to intensive care patients. To assess the effect of 5000 units per millilitre heparin locking of non-tunnelled dialysis catheters on systemic anticoagulation, we performed a prospective observational study of ten intensive care patients receiving heparin locking of dialysis catheters in an adult tertiary intensive care unit between July and September 2015. Activated partial thromboplastin time (APTT) was measured prior to, and three minutes after, heparin locking of catheter lumens with the manufacturer's recommended locking volume to assess the effect on systemic anticoagulation. Heparin locking of venous dialysis catheters resulted in a significant rise in APTT (P=0.002). The median rise was by 56 seconds (interquartile range 30-166.5). Following heparin locking, 80% of patients had APTT values within or above the range associated with therapeutic anticoagulation. Heparin locking of non-tunnelled venous dialysis catheters can cause systemic anticoagulation in intensive care patients and therefore poses a potential risk to patient safety.

The use of recombinant activated factor VII for refractory bleeding post complex cardiothoracic surgery.

We reviewed the outcome following use of recombinant activated factor VII (rVIIa) in patients with major bleeding post cardiothoracic surgery in our unit between January 2002 and July 2004. The unit consists of 16 cardiothoracic intensive care beds in a public metropolitan teaching hospital which serves as a referral centre for heart and lung transplant surgery. Patients with refractory bleeding following cardiothoracic surgical procedures who were treated with rVIIa were identified. A total of 12 episodes of rVIIa use were recorded in ten patients, including three episodes with ventricular assist devices, and 5 heart and/or lung transplants. The median dose used was 85 microg/kg. Chest tube drainage decreased in all patients following administration of rVlIIa; median chest tube drainage decreased from 445 ml/h to 171 ml/h (P = 0.03). Despite cessation of bleeding, mortality was high when rVIIa was used after more than 24 hours. In six episodes, despite early rVIIa use (within six hours), continued bleeding necessitated return to theatre, where a surgical source of bleeding was found. In this small retrospective study, rVIIa significantly reduced bleeding that was refractory to standard blood product transfusion. In this series of patients, those that did not respond to rVIIa early in the postoperative phase were found to have a surgical source of bleeding.