Complications of TPN Flashcards
A patient receiving chronic PN therapy develops an intraluminal clot in the central venous access device. What is the most appropriate pharmacological intervention to clear this access device?
alteplase 2mg/2ml
Conventional therapy for an occluded central venous access device (CVAD) due to an intraluminal clot or fibrin sheath is local thrombolytic therapy with a low dose agent in a single or repeated bolus. Cathflow (Alteplase) is the only FDA-approved thrombolytic agent for CVAD occlusions. A dose of 2 mL, or 110% of the volume of the catheter lumen if less than 2 mL (maximum dose 2 mg), is placed in the catheter lumen. Alteplase catalyzes the conversion of clot-bound plasminogen to plasmin and initiates fibrinolysis. In clinical trials, one 2 mg/2 mL dose of alteplase restored function in 67-74% of occluded CVADs and was found to be more effective than urokinase 500 IU. Use of heparin 100 units/mL is appropriate for catheter flushing but not for treatment of CVAD occlusions. Neither argatroban nor stepretokinase is approved for clearance of catheter thrombosis.
A patient has been receiving PN through a central venous catheter (CVC) for the past week while in the hospital. They now present with shortness of breath, cough, and cyanosis of the face, neck, shoulder, and arms. What type of device complication is characterized by this patient’s symptoms?
superior vena cava syndrome
Tunnel infection can be characterized by pain, swelling, erythema, or induration along the subcutaneous tract of a tunneled catheter. Pinch-off syndrome is a complication of subclavian tunneled central catheters with intermittent or permanent occlusion which are related to postural changes. Thrombosis often presents with chest pain, earache, jaw pain, swelling of the arm, shoulder, neck, or face on ipsilateral catheter side, or leaking at the exit or insertion site. Superior vena cava syndrome is characterized by shortness of breath, dyspnea, cough, cyanosis of face, neck, shoulder and arms, and distended chest or neck veins.
Which of the following is an etiology of a thrombotic catheter occlusion?
A fibrin sheath, or fibrin sleeve, is a thrombotic catheter occlusion and develops when fibrin adheres to the external surfaces of the catheter. Nonthrombotic catheter occlusions can result from mechanical obstructions, drug or mineral precipitates, or lipid deposits. Mechanical obstruction may reflect catheter migration or malposition that occurs during insertion or use. Precipitates that form due to drug crystallization, drug-drug incompatibilities, or drug-solution incompatibilities can produce catheter occlusion.
Patients with DM receiving TPN
The standard for glucose checks in a patient with diabetes on PN is every 2-6 hours, depending on facility protocol, insulin requirements, and general clinical condition. Patients with diabetes receiving PN should receive a maximum infusion rate of 5 mg/kg/min, starting at a 100-150gms dextrose/day to avoid hyperglycemia and refeeding. The estimated initial amount of insulin to add to PN for a diabetic is 0.05-0.1 unit insulin/gm dextrose, increased daily to achieve glycemic goals by adding 2/3 of previous days sliding scale insulin. The increase in blood glucose levels seen in diabetic and critically ill patients is associated with higher frequency of infection. The intense counter-regulatory hormone and cytokine responses to severe disease and the excessive administration of glucose, usually as PN, could contribute to hyperglycemia and the associated infectious complications.
Arm, shoulder and neck swelling in a TPN patient
catheter related central venous thrombosis
Arm, shoulder, or neck swelling, limb, jaw, or ear pain, and dilated collateral veins over the arm, neck or chest are hallmark symptoms of catheter related central venous thrombosis. Central venous catheters cause endothelial trauma and inflammation which can lead to venous thrombosis. Inflammation of the vessel wall can cause pain and tenderness along the course of the vein. Obstruction of blood flow may cause collateral vein congestion and edema on the affected side.
The use of 0.1N hydrochloric acid is most effective for clearing catheter occlusions due to precipitation of
calcium-phosphate
rapid infusion of potassium phosphate can result in
thrombophlebitis
Infusion rates of phosphate should not exceed 7 mmol/h because faster infusion rates can often cause thrombophlebitis (ie, potassium phosphate) and metastatic calcium-phosphate deposition with potential resultant organ dysfunction.
Which of the following additives has the greatest risk of destabilizing the lipid injectable emulsion (ILE) in a total nutrient admixture (TNA)?
iron dextran
Phase separation and the liberation of free oil from the destabilization of TNAs can result over time when an excess of cations is added to a given formulation. The higher the cation valence, the greater the destabilizing power; thus, trivalent cations such as Fe+3 (from iron dextran) are more disruptive than divalent cations such as calcium and magnesium. Monovalent cations such as sodium and potassium are least disruptive to the emulsifier, yet when given in sufficiently high concentrations, they may also produce instability. There is no safe concentration of iron dextran in any TNA.
