Millions of central venous and arterial catheters are placed across the United States annually as mechanisms of obtaining advanced hemodynamic monitoring and facilitating acute resuscitation. Although presumably life saving or sustaining in many circumstances, current literature identifies the preprocedural and postprocedural complications of infection, thrombosis, embolism, and iatrogenic injury as resulting in patient morbidity and mortality. Today, through the application of aseptic technique, performance of operator training, and the utilization of ultrasound, emergency physicians may limit vascular access complications and improve patient outcomes.
Key points
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Central venous catheterizations and arterial catheterizations are frequently used in the emergency setting to establish invasive hemodynamic monitoring, perform acute resuscitation, and facilitate the initiation of specialty-directed therapies (hemodialysis and extracorporeal membranous oxygenation).
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Morbidity and mortality associated with vascular access attempts occur secondary to infection, thrombosis, embolism, and iatrogenic injury.
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As the prevalence of chronic kidney disease continues to increase, emergency physicians must be aware of complications associated with hemodialysis vascular access.
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When obtaining central venous access or arterial access in an anticoagulated patient, experts recommend catheterization of a directly compressible vessel.
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Vascular access complications may be limited by the employment of aseptic technique, choice of appropriate cannulation site, operator training, and the utilization of ultrasound.
Introduction
Approximately 8% of individuals presenting to United States emergency departments (EDs) require invasive vascular access procedures during their initial evaluation or subsequent hospitalization. Today central venous cannulation and arterial catheterization are commonly used in the emergency setting to allow for resuscitation, administration of noxious medications, cardiac pacing, extracorporeal therapies, hemodialysis (HD), and hemodynamic monitoring. Because infectious and noninfectious complications related to vascular access are associated with increased patient morbidity and mortality, their prevention and early identification are vital to limiting personal and organizational costs, reducing inpatient hospital days, and improving quality of care.
Introduction
Approximately 8% of individuals presenting to United States emergency departments (EDs) require invasive vascular access procedures during their initial evaluation or subsequent hospitalization. Today central venous cannulation and arterial catheterization are commonly used in the emergency setting to allow for resuscitation, administration of noxious medications, cardiac pacing, extracorporeal therapies, hemodialysis (HD), and hemodynamic monitoring. Because infectious and noninfectious complications related to vascular access are associated with increased patient morbidity and mortality, their prevention and early identification are vital to limiting personal and organizational costs, reducing inpatient hospital days, and improving quality of care.
Central venous access
In the United States, physicians insert approximately 5 million central venous catheters (CVCs) annually. Although CVCs are highly useful for hemodynamic monitoring, the administration of sclerosing medications, the performance of emergent dialysis, and so forth, the placement of these devices is associated with infectious, thrombotic, and mechanical complications.
Infectious Complications
Central line–associated bloodstream infections (CLABSIs), or catheter-related bloodstream infections (CRBSIs), occur in 0.5% to 1.2% of patients having CVC, a number drastically reduced after the widespread use of sterile precautions. Although the incidence of CLABSIs is variable across health care facilities, current ICU and ED studies report an average 30,000 catheter-related infections per year, with an associated 30-day hospital readmission rate of 37.1%. Treatment costs associated with CVC infection range from $3700 to $36,000 per episode, representing $670 million to $2.68 billion in health care spending annually.
Risk factors
Risk factors for CLABSIs are patient related, catheter related, and operator related. Patient risk factors include immunosuppression, medical comorbidities (peripheral atherosclerosis, diabetes, and recent surgery), increasing severity of illness, and concomitant bacteremia. Catheter-associated risk factors center on the type of catheter used and the site chosen for cannulation. In randomized trials, antiseptic impregnated CVCs (chlorhexidine and silver sulfadiazine or minocycline and rifampin) consistently demonstrate lower rates of CLABSIs compared with their nonimpregnated counterparts. As an example, a study of 453 CVCs, performed by Maki and colleagues, identified a 5-fold reduction in catheter-associated blood stream infections (1.6 compared with 7.6 infections per 1000 catheter days; relative risk 0.21 [CI, 0.03–0.95]; P = .03) with the utilization of antiseptic catheters. In terms of cannulation site, research has demonstrated subclavian venous catheterization (infection rate of 0.5%) as associated with fewer infectious complications compared with jugular venous and femoral venous access (infection rates of 1.4% and 1.2%, respectively). Risk of infection greatly increases if sterile precautions are not used. Current evidence also suggests that subclavian venous cannulation is less likely to result in an infectious complication compared with catheterization of the internal jugular vein; however, randomized, controlled trials are needed. As with any medical procedure, complication rates are intimately associated with operator experience. Practitioner implementation of sterile barrier precautions, including mask, cap, sterile gown, and sterile gloves and the employment of cutaneous antiseptics have been shown to save approximately $167 per CVC inserted (estimated funds allocated to CLABSI treatment measures in the setting of poor sterile precautions).
Identification and treatment of a central line–associated bloodstream infections
In an effort to improve heath surveillance efforts, the Centers for Disease Control and Prevention (CDC) has formally defined a CLABSI/CRBSI as a laboratory-confirmed bloodstream infection occurring in the presence of a CVC or within 48 hours of the CVC removal. CLABSIs/CRBSIs are associated with significant attributable mortality (5%–25% ) and substantial economic burden (increasing average length of stay by 14 days; associated with an additional cost of $2002 per patient).
A CLABSI or CRBSI should be suspected in patients with CVCs presenting with signs and symptoms of a systemic inflammatory response (ie, temperature less than 36°C or greater than 38°C, heart rate greater than 90 beats per minute, respiratory rate greater than 20 breaths per minute, or white blood cell count less than 4000/μL or greater than 12,000/μL). All sites of central venous cannulation should be inspected for erythema, induration, fluctuance, skin maceration, and purulent drainage. Assessment for a CLABSI or CRBSI should include the removal of the CVC, culture of the catheter tip, 2 peripheral blood cultures, and initiation of antimicrobial therapy. Common pathogens causing CLABSIs/CRBSIs include Staphylococcus aureus , Pseudomonas aeruginosa , coagulase-negative staphylococci, and gram-negative bacilli. The initiation of antibiotics targeting these organisms is advised. Antifungals targeting Candida spp should be administered for all patients receiving total parenteral nutrition, because this glucose-rich medium predisposes to CLABSI and systemic fungemia.
Initiatives to reduce the incidence of central line–associated bloodstream infections/catheter-related bloodstream infections
Several agencies have released evidence-based guidelines for the reduction of CLABSIs/CRBSIs. The most recent, a publication by the CDC Healthcare Infection Control Practices Advisory Committee, offers a systematic review of 12 years of CVC research data, identifying best practices proven to reduce CLABSIs/CRBSIs.
Recommendations contained within the CDC’s Making Healthcare Safer (supported by metrics regarding declines in infections rates with the use of hand washing prior to CVC placement, the use of sterile barrier precautions, chlorhexidine for skin antisepsis, and so forth), when used in conjunction with the CDC National Healthcare Safety Network CLABSI/CRBSI surveillance program, have allowed thousands of medical facilities across the nation to improve CVC insertion and reduce the morbidity and mortality associated with infectious complications (50% decrease in CLABSIs between 2008 and 2014; 3655 acute care facilities across the United States reporting).
Thrombotic Complications
Although reports vary widely according to study design, duration of follow-up, and screening modality, catheter-related thrombosis (CRT) is estimated to occur in 0.5% to 1.4% of patients after central venous cannulation. Insertion of a CVC results in local vascular injury and the mechanical obstruction of blood flow. In this setting, fibrin deposition occurs within hours of catheter placement and may result in the formation of a pericatheter sheath (fibrin sleeve), catheter lumen thrombus, or deep vein thrombosis. Although a majority of thrombi associated with CVCs are asymptomatic, the presence of CRT predisposes to bacterial colonization and catheter-related sepsis as well as thromboembolic events.
Risk factors
CRT risk factors are related to patient and catheter characteristics. Individuals with a history of inherited thrombophilia or malignancy, acquired hypercoagulability (heparin-induced thrombocytopenia), those undergoing chemotherapy or receiving treatment with erythropoiesis-stimulating agents, or those with a history of CRT or CLABSI are at an increased risk for developing CRT. Features of CVCs associated with increased risk of CRT include larger catheter size and site used for placement. In randomized trials, routine studies to assess for venous thrombosis after catheter placement have identified increased risk of CRT associated with femoral and internal jugular venous cannulation compared with subclavian cathterization.
Identification and treatment of thrombosis
Because examination is not sensitive or specific for CRT, patients presenting with ipsilateral extremity edema, or those with localized tenderness, edema, or erythema at the CVC site should undergo formal evaluation with Doppler ultrasonography (US). US evaluation is also indicated in the event that samples cannot be withdrawn, or infusions delivered, through the CVC. The use of contrasted CT and MRI should be considered for patients suspected of having an intrathoracic CRT with normal or nondiagnostic US.
The management of CRT centers on reducing symptoms, limiting extension of thrombosis, and preventing chronic venous occlusion. To date, however, no randomized controlled trials of acute or long-term therapies for CRT have been undertaken. Because current evidence has failed to demonstrate improvement in patient outcomes after CVC removal in the setting of CRT, experts recommend that the catheter remain in place unless it is nonfunctional, infected, or no longer needed. If a catheter-related thrombus is identified, the American College of Chest Physicians recommends therapeutic anticoagulation during CVC and for a duration of 3 months after CVC removal. Because studies regarding the safety and efficacy of various anticoagulant therapies (vitamin K antagonists, direct thrombin inhibitors, and factor Xa inhibitors) in the treatment of CRT are ongoing, current recommendations regarding therapy are lacking. Today case studies report the comparative safety of catheter-directed thrombolysis in addressing upper extremity CRT; therefore, consultation should be considered in this setting.
A thrombus isolated to a catheter lumen may be managed with removal and replacement of the CVC versus instillation of a thrombolytic. Both alteplase and tenecteplase have been shown to relieve 80% to 90% of catheter occlusions within 1 hour to 2 hours of instillation.
Prevention of thrombotic complications
Strategies previously proposed to limit the incidence of thrombotic complications after CVC include cannulation of the subclavian vein, proper placement of subclavian and internal jugular CVCs, the employment of catheter flushes, and thromboprophylaxis. Regarding appropriate placement, a 2011 meta-analysis of 5 randomized controlled trials and 7 prospective studies (n = 5636 subjects) revealed an increased risk of CRT for catheter tips placed outside of the junction of the superior vena cava and right atrium (odds ratio [OR] 1.92; CI, 1.22–3.01). Thus, emergency physicians should examine postprocedure radiographs to localize the catheter tip. With regard to the other proposed strategies, routine heparin and saline flushes have failed to demonstrate a reduction in the incidence of CRTs. Because numerous meta-analyses have failed to demonstrate a benefit of thromboprophylaxis in the prevention of CRTs, clinical practice guidelines currently recommend against the routine use of prophylactic anticoagulation in patients with a CVC.
Mechanical Complications
Mechanical complications associated with CVC occur in 0.7% to 2.1% of catheterization attempts and include arterial injury, pneumothorax, hemothorax, air embolism, and cardiac dysrhythmia. Arterial puncture is a well-documented complication of central venous cannulation. Arterial cannulation (occurring during 4.2% to 9.3% of all line placements ) is encountered most often during femoral catheterization attempts. Inadvertent arterial puncture can lead to uncontrolled hemorrhage, hematoma formation, pseudoaneurym, arteriovenous (AV) fistula, and embolic phenomenon.
Pneumothorax complicates approximately 1% of CVC placements and is most often related to subclavian cannulation. Hemothorax is associated with 0.4% to 0.6% of subclavian catheterization attempts. Air emboli are rare, but depending on the volume of air instilled, may result in complete cardiovascular collapse due to limitations in left ventricular diastolic filling and decreased coronary perfusion. Cerebral air emboli, occurring in patients with a patent foramen ovale, have a mortality rate of 23%. Cardiac dysrhythmias may occur during CVC from guide wire contact with the right atrium, most frequently manifesting as premature atrial and ventricular contractions. Prolonged guide wire stimulation of the atrioventricular node may result in supraventricular tachycardias predisposing to fatal dysrhythmias.
Risk factors
Mechanical complications have been shown to increase with repeated cannulation attempts. Similar to infectious complications of CVC placement, the risks of arterial injury, hemothorax, and pneumothorax vary according to the site chosen for cannulation. Placement of a subclavian central line is more likely to be complicated by pneumothorax and hemothorax compared with internal jugular catheterization, and, as discussed previously, placement of a femoral central line is more commonly associated with arterial injury. Patients with bleeding diathesis or those taking anticoagulants experience increasing morbidity and mortality secondary to vascular injury.
Air emboli may occur with inappropriate patient positioning, failure of hub occlusion during line placement, or the delivery of air with line flushing. Individuals with atrial or ventricular septal defects may transmit air emboli into systemic circulation leading to hemodynamic compromise. As discussed previously, patients with a patent foramen ovale may suffer from cerebral air emboli.
Identification and treatment of mechanical complications
Arterial puncture, often identified by pulsatile blood flow from the catheterization site, may be difficult to identify in a critically ill, septic, or hypoxemic patient. If questions regarding arterial cannulation exist, experts recommend blood gas analysis or the placement of single-lumen catheter over guide wire followed by connection to a transducing system to identify arterial waveforms. Although catheter removal and the application of direct pressure are appropriate interventions the setting of femoral arterial puncture, current studies indicate increased risk of expanding hematoma causing airway obstruction, stroke, and pseudoaneurysm when this method is applied to cervicothoracic arterial injury. In this scenario, consultation for endovascular repair is indicated. If concern for arterial puncture with resultant hematoma formation in a noncompressible anatomic location (ie, intrathoracic or retroperitoneal) exists, advanced imaging should be considered, and consultation with a cardiothoracic, vascular, or interventional radiologist performed as appropriate.
Large pnemothoraces occurring as a result of CVC placement may rapidly be identified due to patient hemodynamic instability and hypoxia, thereby necessitating emergent tube thoracostomy. Postprocedural chest radiographs (CXRs) demonstrate poor sensitivity (31%) in the detection of pneumothoraces. CT remains the gold standard for diagnosis of a pneumothorax. Compared with a CXR, US demonstrates increased sensitivity (88.1%–95.3% ) and may be used as an expedient method of evaluation. Supplemental oxygen therapy and hemodynamic monitoring is indicated for pneumothoraces involving less than 15% of the involved lung volume; all others require tube thoracostomy.
Studies identify CXR and US as demonstrating comparable sensitivity in the detection of hemothoraces (92%–96.2% and 81%–97.5%, respectively ). Similar to pneumothoraces, CT is the definitive diagnostic modality. All hemothoraces require treatment with tube thoracostomy to prevent the later complications of empyema and fibrothorax. In cases of massive hemothorax, urgent surgical consultation and transfusion of blood products may be required.
Telemetry monitoring during the placement of subclavian and internal jugular CVCs is useful because it allows for the prompt identification of dysrhythmias caused by atrioventricular nodal irritation. Catheter repositioning on identification of premature contractions is recommended. Although a majority of air emboli are subclinical, patients receiving a large volume of air delivered to the vasculature may present with dyspnea, tachypnea, hypoxia (pulmonary air emboli), cardiovascular compromise (untreated atrial septal defect or ventricular septal defect), or neurologic sequelae (patent foramen ovale). The diagnosis of air embolism is clinical as advanced imaging (CT pulmonary angiography/echocardiography) is commonly without diagnostic finding. If suspected, treatment with high-flow oxygen should be initiated immediately. In extreme cases, depending on the duration and severity of symptoms, hyperbaric oxygen therapy may be required.
Prevention of mechanical complications
Meta-analyses demonstrate significant risk reduction of arterial puncture, hematoma, pneumothorax, and hemothorax with the use of US-guided CVC compared with landmark methods (reducing complications rates previously as high as 11.8% to 4%–7%).
Operator experience is paramount in CVC placement, because the number of unsuccessful cannulation attempts is the greatest predictor of mechanical complications. The complication of cardiac dysrhythmias may be reduced with anticipation and knowledge of guide wire depth.
Arterial access
Approximately 8 million peripherally inserted arterial catheters are placed in the United States annually, partly due to their utility in hemodynamic monitoring. The majority of arterial access is obtained through the radial artery, owing to ease and speed of placement and high success rate of cannulation; however, percutaneous arterial access may also be achieved through cannulation of the brachial, axillary, or femoral arteries. Although it is a procedure often performed in the emergency setting, data regarding arterial catheterization are described primarily in cardiology and anesthesiology literature. These sources detail the well-known complications of arterial cannulation: transient vascular occlusion, hematoma, hemorrhage, infection, pseudoaneurysm, air embolism, and neurologic injury.
Complications of Arterial Access
Frequently associated with radial artery cannulation (mean incidence 19.7% of all radial attempts ), transient vascular occlusion may result from mechanical obstruction and subsequent thrombosis. In contrast, axillary and femoral artery cannulation are much less likely to result in vascular occlusion (0.20% and 1.45%, respectively ), likely secondary to increased vessel diameter. Hematoma formation occurs in approximately 6% of all femoral access attempts. The most feared complication of femoral arterial access, retroperitonal hemorrhage, occurs in 0.15% of all femorally placed CVCs. Retroperitoneal hematoma and hemorrhage are associated with significant morbidity and mortality. In patients undergoing cardiac catheterization, retroperitoneal hematoma has been associated with increased risk of infection/sepsis (17.43% vs 3.00%, P <.0001) and increased in-hospital mortality (6.64% vs 1.07%, P <.0001). Retroperitoneal hemorrhage in this population carries an attributable mortality of 4% to 12%.
Rates of local and systemic infections associated with arterial catheter placement have been estimated as 10% to 20% and 0.4% to 5%, respectively. Arterial line blood stream infections are associated with pseudoaneurysm, thromboarteritis, and arterial rupture. As discussed previously, CRBSI/CLABSI definitions also apply to infections related to arterial access. Similar to central venous CRBSI/CLABSI, data regarding the incidence of this complication is reported to the CDC NHSN. Although femoral access has historically been implicated as the arterial access site associated with a majority of arterial-catheter related bloodstream infections, a recent analysis of more than 4932 ICU patients demonstrated similar infection rates with catheterization of radial and femoral sites.
Iatrogenic pseudoaneurysms predominately occur after cannulation of the radial artery (incidence of 0.09% ) and femoral artery (incidence 0.1%–0.2% ). Although rare, pseudoaneurysm rupture, distal embolization, and compression neuropathy may result in significant morbidity.
Air embolism is an infrequently reported complication of radial and axillary artery cannulation but may inadvertently occur with flushing of the line. Because axillary artery catheterization is also associated hematoma formation and subsequent brachial plexopathy, cannulation is not recommended in an ED.
Risk Factors
Numerous risk factors have been identified for arterial vascular occlusion: increased catheter size compared with vessel diameter, number of access attempts, duration of cannulation, and patient hemodynamic status (hypotension or the requirement for inotropes or vasopressors). Risk of retroperitoneal hematoma and hemorrhage increases when cannulation is attempted at an anatomic location superior to the inguinal ligament. Access attempts at this location increase the risk of uncontrolled bleeding, given the inability to achieve hemostasis through direct compression. Women are predisposed to retroperitoneal hematoma and hemorrhage with femoral access attempts. Experts attribute this fact to the smaller diameter and shorter length of femoral arteries in women compared with their male counterparts, making femoral access increasingly challenging and contributing to the need for multiple attempts. Smaller body surface area (associated with a smaller diameter femoral artery) is also a risk factor for retroperitoneal hemorrhage and hematoma.
Poor aseptic technique during placement and prolonged duration of cannulation (>96 hours) increase the rates of systemic and local infection occurring as a result of arterial access. Risk factors for pseudoaneurysm formation include number of access attempts and coagulopathy. Risk factors for air embolism are similar to those seen with CVC: failure of catheter hub occlusion and the inadvertent delivery of air with flushing. Direct nerve injury has been reported with improper needle placement, and hematoma formation has been associated with multiple cannulation attempts.
Identification and Treatment of Complications
A majority of identified cases of radial artery vascular occlusion remain asymptomatic secondary to collateral circulation. Rare complications, including distal limb ischemia and clot embolization, occur in less than 0.01% of all documented cannulation attempts. Patients experiencing extremity pain, paresthesias, or pulse deficit (a late finding) should undergo evaluation by Doppler US. In the setting of concern for distal limb ischemia, angiography should be considered as appropriate. In severe cases, expert consultation may be required for the performance of thrombectomy. All patients with identified arterial thrombosis should undergo arterial line removal. Although recannulation of an occluded artery occurs spontaneously, this may take up to 75 days; therefore, systemic anticoagulation is indicated.
Hemorrhage is a feared complication of femoral artery cannulation. Common complaints associated with retroperitoneal hematoma and hemorrhage include lower abdominal, back, or flank pain and abdominal fullness. Hypotension and bradycardia may be late findings. In the setting of retroperitoneal hemorrhage, emergency physicians should consider urgent consultation with vascular surgery or interventional radiology, because operative intervention or embolization may be required. In the setting of hemodynamic instability, resuscitation with the transfusion of blood products may be necessary as a temporizing measure.
Similar to patients with CVCs, CRBSI/CLABSI should be suspected in patients with arterial catheters presenting with systemic inflammatory response syndrome criteria/sepsis or those with erythema, induration, fluctuance, or purulent drainage from access sites. After blood cultures and line removal, antibiotic/antifungal (if total parenteral nutricion) therapy is advised.
Hematoma and pseudoaneurysm formation secondary to vascular access both commonly present with localized pain. Pseudoaneurysm may be detected with the new onset of a thrill or bruit. If a patient is reports pain in a nerve root distribution or if a neurologic deficit is elicited on examination, Doppler US should be performed to rule out hematoma or pseudoaneursym.
Depending on the volume and speed of air delivered, patients with air emboli often detail the sudden onset of chest pain, palpitations, shortness of breath, or new neurologic symptoms. Electrocardiogram may demonstrate tachycardia, acute ST segment changes, or evidence of right heart strain. All patients with suspected arterial air emboli should receive supplemental oxygen therapy via a nonrebreather mask to maximize end-organ oxygenation. CT angiography may be used to assess emboli burden; however, as discussed previously, this study may be nondiagnostic. In the setting of hemodynamic instability or significant neurovascular symptoms, hyperbaric oxygen therapy should be considered within 6 hours of insult (studies demonstrating improved neurologic outcomes when initiated within this time frame).
Prevention of Arterial Access Complications
As discussed previously, thrombus formation and subsequent arterial occlusion result from direct tissue injury and the mechanical obstruction of blood flow. Although clinically significant thrombi localized to the brachial, axillary, and femoral arteries are rare, those localized to the radial artery more commonly result in the sequelae detailed previously. To minimize the risk for clinically significant radial arterial thrombi, a 20-gauge catheter should be used during cannulation (the incidence of radial obstruction increases as the catheter lumen diameter more closely approximates the vessel lumen diameter). Limiting the duration of radial catheterization has also been demonstrated to decrease the occurrence of arterial thrombi.
Similar to CVC, the use of sterile technique, preparation, and occlusion of the catheter hub during placement and a working knowledge of anatomy significantly reduce the risk of hemorrhage, infection, and air emboli.
Finally, several studies have identified the benefits of US-guided arterial access. These include increased accuracy of vessel cannulation, reduced number of attempts, increased patient comfort, and reduced risk of complications, such as hemorrhage, hematoma formation, pseudoaneurysm, and neurologic injury.
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