Page 312 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

216 PART 2: General Management of the Patient

lower extremities to monitor for complications of angiography, particu- trauma, recent surgery, pregnancy, and ongoing infection. Because
larly groin hematoma, femoral arterial patency, or distal embolization. thrombolytic therapy typically requires at least 6 to 8 hours of con-
Given the risk of nontarget spinal cord embolization, neuromuscular tinuous infusion prior to improvement in ischemia, patients with rapidly
checks should be obtained at frequent intervals. progressing or profound ischemia are better served by more immediate
■ RESULTS AND COMPLICATIONS clot removal that can be achieved using surgical means. Patients must be
able to lie flat and cooperate during infusion therapy. The most impor-
The largest review of bronchial artery embolization documented imme- tant fact to recognize is that successful thrombolysis merely reestab-
diate control of hemoptysis in 91% of 306 patients. In the vast majority lishes the baseline condition. Therefore, after successful thrombolysis,
24
of patients, embolization is treating a symptom of the underlying disease additional therapy such as angioplasty, surgical revision, or anticoagu-
rather than the disease itself. As such, rebleeding is not uncommon, espe- lation must be pursued to ensure a durable result. If no further therapy
cially in patients with chronic disorders such as cystic fibrosis. Recurrent is undertaken, repeat thrombosis is a foregone conclusion.
hemoptysis may be due to bronchial artery recanalization, hypertrophy Checklist: Pretherapy labs include complete blood count, prothrombin,
of a bronchial artery not previously embolized or visualized, or devel- partial thromboplastin, fibrinogen, fibrin degradation products, and
opment of nonbronchial systemic collateral arteries. In these cases, the INR. Blood products should be typed and screened prior to therapy.
procedure can be repeated. Bronchial artery embolization does not inter-
fere with subsequent lung transplantation. Procedure: For arterial thrombolysis of the leg (Fig. 30-11), the com-
Spinal cord ischemia is exceedingly rare, especially with good-quality mon femoral artery contralateral to the affected side is the typical access
angiography. It occurs in less than 1% of cases but should be discussed site. For venous thrombolysis, the popliteal vein or an infrapopliteal
routinely with patients in the informed consent process prior to embo- vein on the affected side is punctured. After securing access, a vascular
lization. Transverse myelitis has also been reported but is attributed sheath is inserted. The sheath is used for several functions. It stabilizes
to older ionic contrast media, which is no longer commonly in use. the infusion catheter, is used to administer a low dose of heparin during
Bronchial infarction and bronchoesophageal fistula have been reported infusion (typically ∼300 IU heparin per hour), and enables blood to
with the use of liquid embolic agents, which are also not commonly be drawn without needle punctures (which are contraindicated during
utilized currently. Transient chest pain and dysphagia may be encoun- thrombolysis). After sheath insertion, either diagnostic angiography
tered due to embolization of posterior mediastinal and midesophageal or venography is performed to assess clot burden and extent. If the
branches and is usually self-limiting. thrombosed vessel or graft is able to be catheterized, a soft tipped guide
wire is advanced distally through the clot. This guide wire traversal test
gives prognostic information regarding potential success of thromboly-
CATHETER-DIRECTED ARTERIAL sis. Hard thrombus (ie, chronic and organized) tends to be resistant to
AND VENOUS THROMBOLYSIS thrombolysis and portends a poor prognosis for endovascular therapy.
Commonly, a small dose of thrombolytic agent (eg, 2-4 mg of tissue plas-
minogen activator) is laced directly along the entire course of the clot.
KEY POINTS
Subsequently, a multisidehole infusion catheter is positioned directly
• Catheter-directed thrombolysis is best suited for patients with acute into the clot and thrombolysis is initiated. A variety of thrombolytic
(<1 week) arterial or venous thrombosis. agents are available for thrombolysis. At the authors’ institution, t-PA
• Arterial thrombolysis is equivalent or better than surgical throm- is used preferentially although there are no data to demonstrate clear
bectomy in many patients. superiority of one agent versus another. A variety of dosing protocols
also exist. Commonly during the day, the infusion is performed at a
• The rationale for performing venous thrombolysis in the lower extrem- rate of 0.5 mg t-PA per hour (eg, 5 mg of t-PA is mixed in a 500-mL
ity is to prevent valvular damage and postthrombotic syndrome. bag of normal saline and infused at a rate of 50 mL/h) and repeat
■ INDICATIONS AND PATIENT SELECTION angiogram is performed through the infusion catheter every 4 to
6 hours. At night, the same concentration of t-PA is infused but is
continued until the morning. Heparin, which prevents clot from
Endovascular catheter directed thrombolysis is the therapy of choice in forming on the sheath and catheter, is administered through the
many patients with acute arterial and venous thrombosis. Removal of clot sheath at a rate of approximately 300 IU/h.
may be performed with a variety of mechanical devices, by administering
a thrombolytic agent such as tissue plasminogen activator (t-PA), or a ■ IMMEDIATE POSTPROCEDURE CARE
combination of both. (A review of all types of mechanical thrombectomy
devices is beyond the scope of this chapter, so this discussion will be lim- Labs: We monitor routine labs plus complete blood count, prothrombin time,
partial thromboplastin time, fibrinogen, and fibrin degradation products.
ited to pharmacologic thrombolysis.) Compared to systemic thrombolysis,
catheter-directed therapy enables a high concentration of thrombolytic Common Problems That Occur During ICU Infusion: Many patients under-
agent to be deposited in close proximity to or directly within clot. This going catheter directed thrombolysis will not be critically ill but need to
limits systemic complications and facilitates clot dissolution. While any be monitored in the ICU due to the presence of a vascular infusion cath-
vessel in the body may be treated in this manner, in practical terms, this eter and heightened risk of hemorrhage associated with thrombolysis.
type of therapy is most commonly utilized in the extremities. Compared to Patients are kept at strict bed rest with frequent handheld Doppler
surgical thrombectomy or embolectomy, catheter directed therapy is less examinations of the ischemic extremity.
invasive, does not require general anesthesia, and may successfully treat
clot in very small vessels not accessible to a surgical embolectomy catheter. Site Bleeding: Localized bleeding at the puncture site can usually be
Compared to surgical therapy, cardiopulmonary complications are less handled by simply compressing the site for 10 minutes—for refractory
frequent with thrombolysis but bleeding complications are more common. cases, the t-PA infusion is decreased by 50% with increased compres-
■ TECHNIQUE heparin discontinued with continued compression. Finally, cryopre-
sion. For continued bleeding, infusion is again decreased by 50% and
Preprocedure: Patient selection is critical. Absolute contraindications cipitate is given with continued pressure and infusion is discontinued at
discretion of physician.
include a nonviable limb (ie, absent motor and sensory function),
ongoing severe bleeding, and intracranial lesion at risk for hemorrhage. Decreased Fibrinogen: There is no clear protocol for decreased fibrino-
Relative contraindications include but are not limited to recent major gen levels. In some institutions, levels are not even monitored. In

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