Types of Occlusions

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One in 4 catheters may become occluded15

Catheter occlusion is the most common noninfectious complication in the long-term use of central venous access devices (CVADs)17

  • Occlusions may occur in up to 25% of CVADs15,16
  • Thrombotic or nonthrombotic occlusions may occur soon after insertion of a device or develop at any time15-17
Pie chart showing breakdown of types of catheter occlusions : 58% thrombotic and 42% nonthrombotic
THROMBOTIC CATHETER OCCLUSIONS

About 58% of catheter occlusions are thrombotic.16 Thrombotic occlusions result from the formation of a thrombus within, surrounding, or at the tip of the catheter. When introduced into the body, all catheters begin to accumulate fibrin. This is the body’s natural attempt to protect itself against a foreign body. The fibrin starts to form a layer around the outside of the catheter within minutes of insertion, beginning at either the line entry site or where the tip contacts the vein.18,19

Fibrin tail, or flap5

Fibrin tail
  • Extends from the catheter tip but is drawn inward, blocking the opening of the catheter lumen on aspiration attempts
  • Results in an ability to infuse fluids but an inability to withdraw blood

Intraluminal thrombus5

Intraluminal thrombus
  • Occurs when blood refluxes inside the catheter lumen
  • Common causes of reflux include coughing, inadequate flushing after blood draws or after checking for blood return, or improper use of flush syringes

Mural thrombus5,19,20

Mural thrombus
  • Forms where the catheter touches or "rubs" the vein wall
  • Common sites are the entry site, anywhere along the catheter path, and the catheter tip

Fibrin sheath5,19

Fibrin sheath
  • Forms when fibrin adheres to the external catheter surface, which may include the entry site, and may encase all or part of the catheter like a sock
  • May completely cover the opening of the catheter tip

Partial or complete thrombotic occlusions4

  • Partial thrombotic occlusion: ability to infuse but not withdraw fluids, or the presence of sluggish flow
  • Complete thrombotic occlusion: inability to infuse or aspirate
Partial and complete catheter occlusions

Aspirating for a positive blood return may reveal a partial occlusion

Three images: 1) Fibring tail allowing infusion 2) Beginning to flap back with start of withdrawal 3) Blocking aspiration of the catheter

Note that flushing the line is not enough—you must be able to withdraw blood to rule out a partial occlusion before administering critical therapies.1

One quantitative measure for sluggish flow is a blood return of less than 3 mL in 3 seconds, as recommended by the Oncology Nursing Society Advisory Board.7
NONTHROMBOTIC CATHETER OCCLUSIONS

About 42% of catheter occlusions are due to nonthrombotic causes,a including precipitates, malpositioning, mechanical obstructions, and other factors.

Mechanical occlusions17

  • Mechanical occlusions may result from malposition during insertion and use or from catheter migration

  • Factors influencing the incidence of malposition include an increase in intrathoracic pressure from coughing, sneezing, or vomiting; arm movements; and forceful flushing of the catheter

Precipitates17

  • Precipitates can form as a result of drug crystallization, drug-drug incompatibilities, or drug-solution incompatibilities
  • Drug precipitates in the catheter may occur in conjunction with thrombus formation and should always be considered during assessment of an occlusion, since this may have implications for how the occlusion should be managed

Lipid residue17

  • Lipid residue can accumulate in central venous catheters, often following the administration of lipid-containing, three-in-one total parenteral nutrition admixtures or drugs with oleaginous vehicles

Salvaging catheters with nonthrombotic occlusions17

  • In many instances, mechanical problems, such as kinked tubing or clogged in-line filters, can be identified and corrected

    • Possible interventions to reposition catheters include patient positioning, rapid flushing of the catheter, guidewire catheter exchange, fluoroscopic catheter guidance, or partial catheter withdrawal

  • Catheters occluded by calcium-phosphate precipitates can be treated with 0.1 N hydrochloric acid

  • Sodium bicarbonate (1 mEq/mL) is used for substances known to dissolve in an alkaline environment

  • Lipid occlusions have been treated with ethanol (70%) or sodium hydroxide (0.1 mmol/mL)

  • The use of incompatible drugs or solutions should be avoided

aData in this section derived from a study of 200 dysfunctional catheters in 172 adult patients.
Checkmark

Catheter occlusions are categorized as thrombotic or nonthrombotic. An accurate diagnosis of the type of occlusion is essential for appropriate treatment.11

Indication

Cathflo® Activase® (alteplase) is indicated for the restoration of function to central venous access devices as assessed by the ability to withdraw blood.

Contraindications

Cathflo Activase should not be administered to patients with known hypersensitivity to alteplase or any component of the formulation.

Precautions
General

Certain causes of catheter dysfunction should be considered before treatment with Cathflo Activase (e.g. catheter malposition, mechanical failure, constriction by a suture and lipid deposits or drug precipitates within the catheter lumen). These types of conditions should be considered before treatment with Cathflo Activase.

Excessive pressure should be avoided when Cathflo Activase is instilled into the catheter. Such force could cause rupture of the catheter or expulsion of the clot into the circulation.

Bleeding

The most frequent adverse reaction associated with all thrombolytics in all approved indications is bleeding. Cathflo Activase has not been studied in patients known to be at risk for bleeding events that may be associated with the use of thrombolytics. Caution should be exercised with patients who have any condition for which bleeding constitutes a significant hazard.

Should serious bleeding in a critical location (e.g., intracranial, gastrointestinal, retroperitoneal, pericardial) occur, treatment with Cathflo Activase should be stopped and the drug should be withdrawn from the catheter.

Infections

Cathflo Activase should be used with caution in the presence of known or suspected infection in the catheter. Using Cathflo Activase in patients with infected catheters may release a localized infection into the systemic circulation. As with all catheterization procedures, care should be used to maintain aseptic technique.

Hypersensitivity

Hypersensitivity, including urticaria, angioedema and anaphylaxis, has been reported in association with use of Cathflo Activase. Monitor patients treated with Cathflo Activase for signs of hypersensitivity and treat appropriately if necessary.

Drug Interactions and Drug/Laboratory Test Interactions

The interaction of Cathflo Activase with other drugs has not been formally studied. Concomitant use of drugs affecting coagulation and/or platelet function has not been studied.

Potential interactions between Cathflo Activase and laboratory tests have not been studied.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Long-term studies in animals have not been performed to evaluate the carcinogenic potential or the effect on fertility.

Pregnancy

There are no adequate and well-controlled studies in pregnant women. Cathflo Activase should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Adverse Reactions

In clinical trials, the most serious adverse events reported after treatment were sepsis, gastrointestinal bleeding, and venous thrombosis.

You may report side effects to the FDA at (800) FDA-1088 or www.fda.gov/medwatch. You may also report side effects to Genentech at (888) 835-2555.

Please see accompanying full Prescribing Information for additional Important Safety Information.

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