Complications of Central Venous Pressure Monitoring

Complications of central venous cannulation have been recognized since this technique was introduced into clinical practice nearly 50 years ago. Overall, more than 15% of patients undergoing central venous catheterization suffer complications.^[234]

Although serious immediate complications are infrequent when these procedures are performed by well-trained, experienced clinicians, infectious complications remain common, and this procedure continues to result in significant morbidity and mortality. Complications are often divided into mechanical, thromboembolic, and infectious etiologies ( Table 32-6 ).

Mechanical Complications of Central Venous Catheterization

The incidence of complications depends on a number of factors, including the catheter insertion site and the patient's medical condition. Large retrospective and observational studies provide the best estimates of the most frequent complications. In general, unintended arterial puncture

TABLE 32-6 -- Complications of central venous pressure monitoring

Mechanical

Vascular injury

Arterial

Venous

Cardiac tamponade

Respiratory compromise

Airway compression from hematoma

Pneumothorax

Nerve injury

Arrhythmias

Thromboembolic

Venous thrombosis

Pulmonary embolism

Arterial thrombosis and embolism

Catheter or guidewire embolism

Infectious

Insertion site infection

Catheter infection

Bloodstream infection

Endocarditis

Misinterpretation of data

Misuse of equipment

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If arterial puncture with a small needle occurs during central venous cannulation, the needle should be removed and external pressure applied for several minutes to prevent hematoma formation. In the event of unintentional cannulation of the carotid artery with a large-gauge catheter, the preferred clinical management is less certain. In the large series of Shah and coworkers, arterial cannulation with a 7.5-French introducer sheath occurred in four patients.^[249] The sheath was removed immediately when its intra-arterial location was recognized by the high-pressure backflow of blood, and external compression was applied for 5 minutes. No hematoma formation requiring further treatment occurred in any patient. In contrast to this report, others describe hematoma formation after removal of the catheter from the artery, with a significant risk of airway compromise that may require urgent tracheal intubation and surgical exploration for hematoma evacuation or arterial repair.^{[106] [198]} When unintentional carotid artery cannulation occurs, it can usually be managed conservatively by removing the catheter, applying local compression to the puncture site, and monitoring the patient's airway and neurologic status. A vascular surgeon should be consulted promptly to help manage the complication. Under no circumstances should prolonged cannulation of the carotid artery be tolerated because arteritis, thrombus formation, and cerebral embolization may result.^[251]

Vascular injuries from central venous catheterization have a range of clinical consequences. The most common minor complications are localized hematoma or injury to the venous valves.^[171] More serious complications include vascular perforation into the pleural space or mediastinum resulting in hydrothorax, hemothorax, hydromediastinum, hemomediastinum, and chylothorax.^{[229] [252] [253] [254] [255]} Other catastrophic rare vascular injuries have been reported, including aortic perforation ^[256] and avulsion of the facial vein.^[212] Delayed vascular complications after central venous catheterization are uncommon but should be considered as potential consequences of this procedure. A number of these complications have been described in the literature, including aortoatrial fistula, venobronchial fistula, carotid artery-internal jugular vein fistula, and pseudoaneurysm formation.^{[257] [258] [259] [260]}

The most important life-threatening vascular complication of central venous catheterization is cardiac tamponade resulting from perforation of the intrapericardial superior vena cava, right atrium, or right ventricle and the resulting hemopericardium or unintentional pericardial instillation of intravenous fluid.^{[261] [262]} This injury was the single most common fatal complication of central venous cannulation among 3533 cases reported in the American Society of Anesthesiologists Closed Claims Project in 1996.^{[263] [264]} An update from the same project in 2002 revealed that vascular injury remains the most common complication of central venous catheterization, although since 1990, there has been a reduction in the fraction of fatal injuries attributed to cardiac tamponade.^[265] Most reports document the avoidable nature of this catastrophic event and highlight that patients are predisposed to this complication when central venous catheter tips are malpositioned within the heart chambers or abutting the wall of the superior vena cava at a steep angle, recognized radiographically as a gentle curvature of the catheter tip within the superior vena cava.^[266] These observations emphasize that radiographic confirmation of proper catheter tip location is mandatory, regardless of whether the catheter is inserted from a central or peripheral site. In fact, many early reports of catheter-related cardiovascular perforation suggest that peripheral catheters may present unusually high risk for this complication because arm abduction may cause the catheter tip to advance into a dangerous location within the heart.^{[247] [267]} When cardiac tamponade is caused by catheter-induced cardiac perforation, symptoms develop suddenly, so the physician must have a high index of suspicion if severe hypotension occurs in any patient with a central venous catheter in place. Cardiac arrhythmias may provide an early clue to the intracardiac location of the catheter tip.^{[248] [268]} Occasionally, both posteroanterior and lateral chest radiographs and injection of radiopaque contrast are required to locate the catheter tip precisely.^[269]

Pneumothorax is often cited as the most common complication of subclavian central venous cannulation, although it appears that unintended arterial puncture occurs more often than pneumothorax, even with the subclavian site of venipuncture.^{[106] [222]} Mansfield and colleagues reported a 1.5% incidence of pneumothorax and a 3.7% incidence of subclavian arterial puncture in 821 patients who underwent attempted subclavian venous cannulation.^[222] Pneumothorax occurs even less frequently with the internal jugular approach. Shah and coauthors reported a 0.5% incidence of pneumothorax in their series of nearly 6000 internal jugular catheterizations.^[249] This is probably a conservative overestimate because most patients in this series underwent median sternotomy for cardiac surgery, a procedure that may have caused the pneumothorax in many of these patients. Small pneumothoraces may be managed by radiographic observation, with or without needle aspiration, assuming that the patient remains clinically stable. Tube thoracostomy is the best treatment of larger pneumothoraces or pneumothorax in a patient receiving positive-pressure mechanical ventilation or scheduled for major surgery. The physician must always be prepared for the possibility of tension pneumothorax and its adverse hemodynamic sequelae. In addition to pneumothorax, other respiratory tract injuries have been reported to occur with central venous catheterization, including subcutaneous and mediastinal emphysema, tracheal perforation, and rupture of an endotracheal tube cuff.^[270]

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Nerve injury is another potential complication of central venous cannulation. Damage may occur to the brachial plexus, stellate ganglion, phrenic nerve,^[271] or vocal cords.^{[271] [272]} Chronic pain syndromes have been attributed to this procedure as well.^[273]

Thromboembolic Complications of Central Venous Catheterization

Catheter-related thrombosis is a significant risk associated with central venous catheterization, and it occurs in as many as 15% of patients in medical intensive care units.^[234] Subclavian catheters appear to have the lowest risk of this complication. Venous thrombosis may impair venous drainage or lead to superior vena cava syndrome or pulmonary thromboembolism. ^[274] The absolute risk and clinical importance of catheter-related thrombosis remain poorly defined.^[234]

In addition to thromboembolism, other reported embolic complications of central venous catheterization include catheter, guidewire, and air embolism. ^{[213] [275] [276] [277] [278] [279]} Invariably, these complications are the result of misuse of equipment, thereby highlighting the need for proper education and training of nurses and physicians responsible for the use of these devices.

Infectious Complications of Central Venous Catheterization

By far, the most common major late complication of central venous cannulation is infection. Bloodstream infections occur in approximately 5% of patients with standard central venous catheters and lead to an estimated 150,000 to 250,000 cases of catheter-related bacteremia or fungemia annually.^{[183] [280]} Given that the crude mortality associated with nosocomial bloodstream infections is nearly 35% and the cost of these infections can exceed $50,000 per episode, most simple efforts to reduce this complication appear to be both cost-effective and lifesaving. ^{[183] [280] [281]}

As previously noted, the starting point for prevention of infection is meticulous attention to aseptic technique.^[202] When more long-term central venous cannulation is anticipated, the subclavian site is preferred because use of the jugular or femoral veins carries a higher risk of infection.^{[183] [184] [233] [234] [280]} Multilumen catheters are associated with higher risk than single-lumen catheters are, although the added clinical functionality of such catheters often mandates their use.^[282] The type of catheter inserted influences the rate of catheter colonization and subsequent bloodstream infection. Catheters are made from materials such as silicone, polyvinyl chloride, Teflon, and polyurethane. Furthermore, catheters of the same material may be manufactured differently, which influences their surfaces and the frequency of bacterial adherence to the surface. ^[283]

One recent improvement in catheter design has been incorporation of an antimicrobial treatment onto the catheter surface. Combinations of chlorhexidine and silver sulfadiazine or minocycline and rifampin have been shown to reduce rates of catheter colonization and bloodstream infection.^{[183] [234] [280] [281]} Other catheter modifications include the use of a silver-impregnated subcutaneous cuff with catheters intended for long-term use.^[191]

When patients require central venous catheterization for more than 3 to 4 days, some clinicians recommend catheter replacement at a new site, others suggest exchanging the catheter over a guidewire, and still others believe that catheters should not be changed unless there are signs of infection or other clinical indications. ^{[282] [284] [285]} A systematic review of the literature from 1997 suggested that guidewire exchange of central venous catheters might be associated with a greater risk of infection but fewer mechanical complications than occur with placement of the catheter at a new site.^[286] Current guidelines from the Centers for Disease Control and Prevention do not support routine catheter site changes or scheduled changes over a guidewire and provide other detailed recommendations for catheter management to reduce the risk of infectious complications.^[183]

Other Complications of Central Venous Catheterization

Other miscellaneous adverse sequelae of central venous cannulation have been reported (see Table 32-6 ). Although their incidence is not clearly known, most appear to be uncommon. All physicians performing these procedures should recognize them, however, to limit the morbidity of central venous cannulation, particularly because many of these complications result from operator error.^{[106] [264] [287]}

The use of guidewires, vessel dilators, and large-bore catheters carries certain additional risks that mandate meticulous attention to technique. The proximal tip of the guidewire must remain under the physician's control at all times to avoid inserting the wire too far into the heart and thus causing arrhythmias or heart block or potentially losing the guidewire within the circulation.^{[268] [275]} By design, vessel dilators are stiffer than central venous catheters and may cause significant trauma if inserted forcefully or further than necessary to dilate the subcutaneous tissue track from the skin to the vein.^{[264] [288]} Large-bore introducer sheaths and multilumen catheters have become popular because of their clinical usefulness, yet their size may increase the risk of cannulation-associated trauma, hemorrhage from unrecognized line disconnections, and major venous air embolism. Not only may air be entrained during initial cannulation,^[277] but improperly connected large-bore cannulas may also pose an additional risk because of the large site for air entry directly into the central venous circulation.^{[276] [278] [279]}

Unusual complications of central venous cannulation continue to be reported as new catheter modifications are designed, such as the antiseptic catheter surface treatment with chlorhexidine. Although more than 2.5 million of these catheters have been used in the United States without incident, rare but severe anaphylactoid reactions have been reported in Japanese patients.^{[289] [290]} A double-lumen 15.5-French catheter has been designed for use in immunocompromised patients to provide long-term central venous access and an introducer lumen to accommodate a standard pulmonary artery catheter for hemodynamic monitoring. It remains to be seen whether this type of extremely large catheter will create more problems than it solves.^[291]

Although many complications of CVP monitoring relate to equipment misuse, the frequency of complications

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