Page 281 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 27: Intravascular Devices in the ICU 185

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removed. The saline-filled, intravenous extension tubing can be attached CATHETER OCCLUSION
to the catheter in the vessel to confirm a venous or arterial waveform. Occlusion of the CVC is another mechanical complication that occurs
After confirmation of a venous waveform, the guide wire is replaced particularly when catheters have been in place for extended periods of
through this small intravenous catheter, the catheter is removed, and time. Thrombosis at the tip of the catheter may lead to this problem. Tissue
the procedure is finished. If unintentional arterial cannulation occurs, the plasminogen activator may be useful to prevent such occlusions. Other
48
small catheter is removed from the artery and pressure is held at the site. reasons for CVC occlusion include precipitation of incompatible medica-
Such a small catheter is much less likely to cause serious complications, tions, a problem that can be avoided by careful attention to medication
compared to a dilator and large bore catheter. In our teaching hospital, we compatibility. Patients with subclavian catheters may occasionally suffer
stress the importance placing sterile intravenous extension tubing on the from the “pinch off syndrome,” where the catheter is compressed between
sterile field before the procedure is started so that a venous waveform can the clavicle and the first rib. This complication usually occurs in long-term
19
be confirmed prior to dilation and insertion of the CVC. indwelling catheters; however, a narrow space between the clavicle and the
Bleeding complications from both arterial and venous puncture are dra-
matically exacerbated in patients who are thrombocytopenic or those with first rib can sometimes interfere with successful placement of subclavian
catheters, particularly those of large bore caliber. CVCs placed for extended
coagulation disturbances. Unfortunately, such problems are common in time periods have been reported to break and embolize to the right heart or
critically ill patients. Those with platelet counts below 50,000 per microliter pulmonary artery, requiring radiological or surgical removal. 19,49
or those with an international normalized ratio (INR) above 2 should prob-
jugular or femoral vein), unless the clotting problem can be corrected. The ■ CATHETER MISPLACEMENT
ably have catheters placed at a site with compressible vessels (eg, internal
external jugular vein is an alternative that should be considered in those Most CVC placements in critically ill patients are performed without
with clotting disturbances, since this superficial vein is easily compressible. direct real time visualization of the catheter. Typically, a chest radio-
■ PNEUMOTHORAX graph is obtained after the procedure to ensure proper catheter position
and to assess for evidence of a pneumothorax. Malpositioned catheters
Pneumothorax is another important mechanical complication of CVC can then be correctly repositioned. Ideally, thoracic CVCs should ter-
minate in the superior vena cava. Catheters may occasionally terminate
placement. The reported incidence of this complication ranges from 0% to in subclavian or jugular veins, as well as azygous, internal mammary, or
4.5%. Though some studies have reported a higher incidence of pneumo- pericardiophrenic veins, which may result in vascular injury and even
thorax with subclavian catheter placement, a recent meta-analysis did not perforation. When the tip of a catheter is positioned in the right atrium
describe differences in the incidence of this complication when internal or right ventricle, perforation and subsequent cardiac tamponade may
jugular and subclavian approaches were compared. Although many pneu- result. 51,52 In order to avoid complications when CVCs are positioned
11
mothoraces occurring after CVC placement may not require treatment, in cardiac chambers, it is recommended that the tip of the catheter
48
patients undergoing positive pressure ventilation should have the pneu- lie proximal to the angle between the trachea and the right mainstem
mothorax evacuated. The use of small caliber pleural catheters is effective bronchus. Ultrasonic examination after CVC placement may provide
53
as an alternative to conventional tube thoracostomy in evacuating simple an alternative means of assessing adequacy of catheter placement. 60
iatrogenic pneumothoraces ; however, since this therapy has not been
49
extensively tested in patients undergoing positive pressure ventilation, tube ■
thoracostomy remains the conventional therapy in this situation. AIR EMBOLISM
■ THROMBOTIC COMPLICATIONS When there is a communication between the great veins and the atmo-
sphere, air may enter into the venous system. This potential complica-
Catheter-related venous thrombosis is a relatively common complication, tion is particularly relevant when considering the large bore venous
catheters frequently used in critically ill patients. Dysfunctional one-way
occurring in between 2% and 66% of catheters. Catheter-related venous valves or uncapped catheters may allow air to enter the venous system
5,54
thromboses may manifest as either a fibrin sleeve around the catheter or when intrathoracic pressure is subatmospheric during inspiration.
a thrombus that adheres to the wall of the vein and are typically asymp- Another concerning problem is the possibility of venous air embolism
tomatic. Because CVCs injure the endothelium and expose the venous during catheter removal, when a communication from the skin to a great
intima, the coagulation system can become activated, resulting in throm- vein may occur temporarily. The use of Trendelenburg position and
bus formation. Difficulty with insertion of the line appears to increase the bioocclusive dressings may prevent this problem. 54
incidence of thrombosis, presumably due to a greater degree of local In conclusion, intravascular catheters are routinely necessary for the
venous trauma. There is some evidence that in an ICU setting a subcla- management of critically ill patients. Mechanical, infectious, and throm-
56
vian vein CVC is less likely to develop a catheter-related thrombosis than botic complications contribute considerable morbidity and mortality to
an internal jugular vein CVC. Timsit et al used color Doppler-ultrasound these vulnerable patients. Recent evidence suggests that the subclavian
57
just before or within 24 hours of catheter removal to determine the fre- vein may be the most desirable anatomical location for CVC placement;
quency of catheter-related thrombosis associated with 208 CVCs placed in however, thrombocytopenia or coagulation disturbances—common
the ICU (catheters in place for 9.35 ± 5.4 days). A catheter-related internal problems in critically ill patients—may preclude this approach in some
jugular or subclavian vein thrombosis occurred in 42% (CI 34%-49%) and patients. It is encouraging that evidence to guide the appropriate man-
10% (CI 3%-18%), respectively. The overall rate of thrombus formation agement of CVCs is accumulating. Such evidence should allow clinicians
was 33% and an internal jugular CVC increased the risk of thrombus for- to effectively utilize these potentially life-saving devices while minimiz-
mation by a factor of four (RR, 4.13 [95% CI 1.72-9.95]). Importantly, this ing complications associated with their use.
study also determined that the risk of catheter-related sepsis was 2.62-fold
higher when thrombosis occurred (p = 0.011). These findings contradict
two studies that examined the incidence of complications in more perma-
nent tunneled catheters and found a decreased incidence of venous stenosis
and thrombus formation in the internal jugular group as compared with KEY REFERENCES
the subclavian group. 58,59 Finally, the femoral vein is the least desirable • American College of Surgeons. Statement on recommendations
anatomical location with regard to the risk of venous thrombosis. Merrer for uniform use of real-time ultrasound guidance for placement
and colleagues reported 25 of 116 (21.5%) patients randomized to femoral of central venous catheters. American College of Surgeons; 2008.
vein catheterization had ultrasound detected venous thrombosis. This http://www.facs.org/fellows_info/statements/st-60.html. Accessed
differed dramatically from those randomized to subclavian vein catheter- February 4, 2011.
ization, in whom 2 of 107 (1.9%) had venous thrombosis (p < 0.001).

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