Hemodialysis therapy is one of the main renal replacement therapies for
patients with chronic renal failure. Good vascular access is the basic guarantee
for the completion of hemodialysis therapy. An ideal vascular access should be
able to provide adequate blood flow for hemodialysis therapy, be able to use for
a long time and more frequently, and have fewer complications. The establishment
of unblocked and effective vascular access is the key step to maintain the
effect of hemodialysis in patients with renal failure, which directly affects
the quality of life and survival time of patients.
Why central venous catheter?
Although the autologous fistula access is the best choice for maintenance
hemodialysis in patients with chronic renal failure, the number of patients with
poor vascular conditions caused by aging population, diabetic nephropathy, long
dialysis time and other factors is increasing. By patient age, hardening of the
arteries, vascular lesions, caused by repeated puncture vein stenosis, the
patient's own blood vessels, the influence of such factors as more and more
patients can't row from internal fistula, or internal fistula embolism can't
reuse for many times, greatly affecting the effects of the treatment of patients
with hemodialysis, comprehensive analysis of the factors above, long-term
indwelling central venous catheter with polyester set has gradually become the
important pathways of patients.
In the process of overseas dialysis patients' treatment, the dialysis
patients with tapered catheter account for 14% ~ 17.5% of the total dialysis
patients. However, with the increase of patients with long-term hemodialysis
catheterization, the incidence rate of complications with poor function of CVC
is gradually increasing, and has been paid more and more attention by
researchers. The common causes are: thrombosis in the catheter, thrombosis
around the catheter, mural thrombosis, fibrin sheath formation, etc. Poor
catheter function is one of the important factors affecting the survival rate of
dialysis patients, and it is also the main complication of deep venous
indwelling catheter. A common complication of central venous intubation is
catheter thrombosis, which occurs in up to 25% of cases. In order to avoid
long-term use of the catheter, fibrin sheath or thrombosis may occur, resulting
in poor blood flow to the catheter, or even blockage of the catheter.
Catheter dysfunction -- fibrin sheath/thrombosis
According to foreign guidelines, catheter flow rate is less than 300ml/min,
or arterial pressure is less than 250mmHg when blood pump flow rate is less than
300ml/min, or venous pressure is more than 250mmHg, it is considered that
catheter function is poor. In view of the fact that the body weight of domestic
patients is generally lower than that of foreign patients, the expert group
considered that when the catheter blood flow of Chinese adults is less than 200
ml/min, or the blood pump flow is less than 200 ml/min, the arterial pressure is
less than 250mmHg, or the venous pressure is more than 250mmHg, it is unable to
achieve adequate dialysis, and it was determined that the catheter function is
poor. Fibrin sheath and thrombus are one of the main causes of catheter
dysfunction. The standard sealing technique and the correct use of sealing
heparin concentration and volume according to the catheter volume are also
important steps to reduce the catheter dysfunction.
Thrombolysis: thrombolysis should be performed in urokinase catheter due to
the obstruction of catheter flow or difficulty in catheter suction during
loading. At least 5000IU/ml of urokinase is recommended. Urokinase thrombolysis
was maintained in the catheter for 25 ~ 30min. Alternatively, 0.3ml urokinase
solution can be injected every 3 ~ 5min after lOmin is retained. T - PA
thrombolysis can also be used, according to the drug or device manufacturer's
instructions. Repeated thrombosis and poor flow usually require continuous
urokinase infusion. The recommended regimen is to slowly inject urokinase 25,000
~ 50000IU/48ml normal saline through each dialysis catheter at a flow rate of 2
~ 4ml/h, with a duration of at least 6h.
The following procedures are recommended for catheter dysfunction. See the
table below.
Replace the dysfunctional catheter: if multiple thrombolysis is ineffective
or the catheter is ectopic, a new catheter can be replaced. (1) replace the
catheter through the guide wire. When replacing the catheter, most people think
that the tip of the catheter should be about 1 ~ 2cm deep as the original
catheter. (2) replace the puncture site and place a new catheter; (3) the
balloon destroys the fibrin sheath and replaces the new catheter.
Functional maintenance of central venous catheters - regular
thrombolysis
Central venous catheter thrombolysis operating current clinical commonly
used methods: when the syringe suction catheter unilateral or bilateral,
difficulty in pumping blood or cannot extract tube is regarded as intraductal
block, to explain to the patient, ask for details of any UK allergies and
contraindications, confirmation, agreed to explain and patients before
operation, signed informed consent. All routine disinfection for aseptic
operation: group A: 200000 U urokinase dissolve in 50 ml saline, each 25 ml put
in two micro pump, connecting duct arteriovenous side, adjust the micro pump
pumping at the rate of 3 ml/h, 8 h pump, pump after the will of 100000 IU of UK
dissolved in 5 ml saline, with 2.5 ml positive pressure seal tube in the
arteriovenous catheter, 1 times A day, about 2 ~ 3 times, until the next blood
dialysis, the blood flow was observed the situation; Group B: use 20 ml empty
catheter for withdrawing needle connection block end, withdrawing to 2.5 ~ 5 ml
clip pipe clamp, lumen catheter tube to form a negative pressure cavity, after
separation of syringes and catheters, will dilute good 5 ml saline + UK10 IU
syringe pipe, open clamp, using negative pressure to make the UK a liquid inlet
tube cavity and blocking the embolus to fully mix, keep change after 30 mim 20
ml yo try to smoke suction cavity unobstructed, if still owe unobstructed, can
be repeated the operation three times. Thrombolytic therapy was used for both
side and unilateral obstruction.
References on thrombolytic effect of urokinase
Urokinase is an anti-plasminogen preparation produced by the kidney, which
can directly act on plasminogen to convert the activated plasminogen into
plasminogen and form a natural thrombolytic drug, which can promote the
dissolution of thrombus fibrin and cause thrombosis collapse. The thrombolytic
effect of urokinase has not only a strong specificity, but also a small systemic
fibrinolytic effect, which greatly reduces the probability of bleeding, and has
been widely used in clinical thrombolytic treatment. Studies show that urokinase
thrombolysis is a safe and effective method for the treatment of intracatheter
thrombosis, and the catheter recanalization rate can reach 80% ~ 90% after
urokinase thrombolysis. Intravenous pressure measurement of urokinase
intervention patients with regular micro-pump indicated that it could ensure
adequate blood flow and dialysis adequacy. However, the measurement value of
venous pressure in patients with urokinase pushing method suggests that the cuff
patency rate is not good, leading to low hemodialysis flow and the possibility
of insufficient dialysis. Micropump urokinase can not only relieve the
hypercoagulability of the blood, but also reduce the bleeding probability of the
patient, compared with peripheral intravenous infusion, the dose is also within
the range of the patient's viscera.
Relevant research shows that the retention type urokinase thrombolysis
method makes the effect of tube recanalization and pumping method, investigate
its reason, may be due to the slow pumping of urokinase, urokinase gradually
penetrate into the duct wall and catheter around agglutination fibrin, activate
fibrinolytic enzyme, promote the dissolution of fibrin sheath, central venous
catheter in order to avoid formation of fibrin sheath or thrombosis. The
incidence of adverse reactions of micropump urokinase thrombolytic therapy is
lower than that of time-reserved urokinase thrombolytic therapy, which further
proves the safety and effectiveness of micropump urokinase thrombolytic therapy
and is worthy of clinical application. Compared with retained urokinase
thrombolytic method, micropump urokinase thrombolytic therapy can significantly
reduce the incidence of catheter dysfunction and improve the adequacy of
dialysis, which is safe and effective and worthy of clinical application.