Complications of Embolism in Catheters during Hemodialysis - Case Study Example

Complications of Embolism in Catheters during Haemodialysis Introduction Patients with chronic renal failure present a grave condition which has to be continuously monitored in an advanced medical facility and haemodialysis is an oft repeated procedure which has to be carried out with meticulous care and expertise. Cuffed, tunnelled dual lumen central venous catheters (CVCs) were introduced to facilitate dialysis in such patients in the early 1980s (Lok, 2006). Since then there have been numerous advances in the designing and composition of the catheters as they have proved to be an immediate and effective lifeline for haemodialysis patients (Lok, 2006). Minimization of infection due to catheters, improvement of flow rate and the prevention of thrombo-embolism are some of the factors which have determined research activities in this area (Lok, 2006). As the intensity of catheterization has doubled since their initial use the risk of occurrence of complications arising due to such procedures has also increased which can put tremendous stress on the patients’ health as well as finances. Catheterization has a significant effect on the clinical outcome in such patients due to the high incidence of morbidity and mortality (Tal & Ni, 2008). Purpose of Using Anticoagulants in Catheters A variety of anticoagulants have been used in the CVCs to prevent thrombo-embolism and anticoagulant management in haemodialysis in itself is a vital area of therapeutic intervention per se in dialysis patients (Lo et al, 2005). Dialysis patients are prone to venous thromboembolism as well as atrial fibrillation and warfarin and low-molecular weight heparins are frequently used in such cases (Lo et al, 2005). Patients with end stage renal disease (ESRD) are more prone to a hypercoagulable state due to the development of a biochemical milieu in which there is elevation of particular prothrombin fragments and thrombin-antithrombin complexes (Lo et al, 2005). This necessitates effective control measures in such patients for the control of embolus formation all along the course of haemodialysis. Sodium citrate and heparin in various forms are the preferred agents for prevention of embolus formation in patients undergoing haemodialysis due to renal impairment. Continuous renal replacement therapy (CRRT) is frequently used as a preventive measure in high risk kidney patients (Bagshaw et al, 2005). The Study When CVCs are used in patients undergoing haemodialysis, thrombosis at the catheter surface itself poses a big problem which affects dialysis quality as well as catheter survival (Grudzinski et al, 2006). A study by these authors has attempted to weigh the pros and cons of using Sodium citrate as a catheter – locking solution by comparing it to the use of Heparin for the same purpose. The authors have used a multi pronged approach by a retrospective analysis of replacement of all catheters with 4% Sodium citrate instead of the usual Heparin which was used at the rate of 10, 000 IU/ mL and measuring the outcomes by the analysis of Flow related catheter exchange rate, prevalence of INR (prothrombin time/international normalized ratio) assay interference, tissue plasminogen activator (rt-PA) utilization rate, rate of bacteraemias and the annual financial implications (Grudzinski et al, 2006). One major factor during chronic dialysis therapy has been identified as the spiralling cost of treatment which is confounded if the indwelling central venous catheters have to be replaced due to partial or total thrombosis. Catheter malfunction is associated with lowering the quality of life of the patient, increasing morbidity and put a definite strain on dialysis resources (Grudzinski et al, 2006). The use of heparin as the catheter-locking agent is a popular measure to prevent thrombus formation although its implications in terms of efficacy as well as safety in in situ placement are unknown (Grudzinski et al, 2006). In fact, the dosage at which it should be used for the purpose has still not been standardized and there have been occasions of adverse effects such as unintentional systemic anticoagulation which has threatened the life of such patients due to the resultant bleeding complications (Grudzinski et al, 2006). As an alternative, the use of Sodium citrate as a substitute has been a popular measure for several years with the added advantage of a different mechanism of action of its anticoagulant activity i.e. by the chelation of ionized calcium in blood as well as other tissues by its citrate ion with the resultant prevention of any activation of calcium dependent coagulants (Grudzinski et al, 2006). This results in the prevention of the systemic after effects of heparin, which can be disastrous for the patient. A comparative retrospective analysis was done in this study by converting to the locking of all CVCs with sodium citrate at a concentration of 4% at the in-centre haemodialysis unit. Full one year span multiple data of use with either agent was collected for the respective years for comparative analysis. Factors which might contribute to variability in the two respective years such as age, dialysis vintage, previous dialysis history, presence or absence of diabetes mellitus and patient outcome were taken into consideration. In case of any mortality during the study period, the cause of death was ascertained to yield a more accurate analytical data. Patients receiving dialysis either in part or for the total duration of the respective two years were covered in the study. Contribution to variations in results due to concomitant medications which might affect the measurable end points was also taken into consideration. In order to obtain accurate analytical data, standard dosage protocols, both for heparin (1000 U/mL) as well as sodium citrate (4%) were followed. Patient consent was not obtained because the study design involved a unit policy change at the centre. Four different models of catheters were used although they were similar in the respect that all were permanent, tunnelled and double lumen (Grudzinski et al, 2006). The process of locking with either agent was identical. After each haemodialysis session, the catheter lumen was flushed with 10 mL of normal saline, the locking agent was then instilled into the catheter according to its luminal capacity. If partial or full clotting was encountered in any catheter, it was treated with rt-PA (2 mg in each lumen) in order to restore catheter patency. For the respective years, when either of the two locking agents was used, the radiology reports for haemodialysis catheter exchanges were collected, taking care that only exchanges related to poor flow were incorporated into data collection. Catheter exchanges related to other conditions such as infection, etc, were excluded. The number of catheter exchanges per 100 catheter days was calculated by dividing the number of line exchanges by the number of catheter days (Grudzinski et al, 2006). Anticoagulation in the patients under study was adjusted by weekly measurements of INR whose values were corrected for variations due to any interfering mechanisms. Utilization reports for rt-PA were generated from computer records for both heparin and sodium citrate periods. Similarly the microbiological reports were collected for the respective years from the computer records for analysis. Financial data while using either of the agents was also collected for evaluation. Appropriate statistical methods and software were employed for the analysis. Results The total number of catheter days were 30 925 for the patients in whom heparin was used and 37139 in case of sodium citrate. The patients’ characteristics between the two groups did not show any significant difference. There was no difference between the two groups in cases where concomitant medication with warfarin, aspirin and clopidogrel was practiced. The figures for catheter exchanges per 100 catheter days were 1.81 and 1.88 when heparin and sodium citrate were used respectively. Average INR and PTT values were however higher in the heparin group which was explained on the basis of the likelihood of sample contamination with heparin. The rt-PA utilization rates also did not show any significant variation between the two groups. 24 bacteraemias were encountered during the heparin group as compared to 35 in the sodium citrate group. The major difference between the two groups was the financial aspect as the cost of locking catheters was $ 6.46 CAD with heparin and only $ 0.94 CAD with sodium citrate. Analysis and Conclusions The study showed that there was a definite advantage in studying the possibility of sodium citrate use at a concentration of 4% for locking the CVC catheters in haemodialysis patients instead of heparin as it had dramatically reduced the financial burden of the procedure for the patient as well the institution. The financial aspect is a major one in critical case patients of ESRD whose numbers have increased dramatically over the last few years. Moreover the use of sodium citrate eliminated the risk inherent in heparin use which sometimes complicates the morbidity status associated with systemic anticoagulant activity thereby increasing the risk of internal bleeding in such patients. The concentration of sodium citrate used i.e. 4% is also safe as it eliminates the risk of cardiac arrest when used as a bolus injection (Grudzinski et al, 2006). When combined with appropriate drugs like antibiotics it also decreases the rate of catheter infection. The efficacy of sodium citrate as a locking agent has been proven to be equivalent to that of heparin in this study with the added advantage of it being a more economical proposition. References Bagshaw S.M., Laupland K.B., Boiteau J.E. et al. 2005. "Is regional citrate superior to systemic heparin anticoagulation for continuous renal replacement therapy? A prospective observational study in an adult regional critical care system", Journal of Critical Care 20, 155– 161 Grudzinski L., Quinan P., Kwok S. et al. 2006. "Sodium citrate 4% locking solution for central venous dialysis catheters—an effective, more cost-efficient alternative to heparin", Nephrol Dial Transplant 22: 471–476 Lo D.S., Rabbat C.G. & Clase C.M. 2005. "Thromboembolism and anticoagulant management in haemodialysis patients: A practical guide to clinical management", Thrombosis Research 118, 385—395 Lok C.E. 2006. "Avoiding Trouble Down the Line: The Management and Prevention of Hemodialysis Catheter-Related Infections", Advances in Chronic Kidney Disease, Vol 13, No 3, pp 225-244 Tal M.G. & Ni N. 2008. "Selecting Optimal Hemodialysis Catheters: Material, Design, Advanced Features, and Preferences", Tech Vasc Interventional Rad 11:186-191 Read More