SAFETY MONITOR A periodic column from the Pennsylvania Patient Safety Authority
Preventing Central Line Air Embolism Recommended practices for central line insertion, management, and removal. The Pennsylvania Patient Safety Reporting System is a confidential, statewide Internet reporting system to which all Pennsylvania hospitals, outpatient-surgery facilities, birthing centers, and abortion facilities must file information on incidents and serious events. Safety Monitor is a column from Pennsylvania’s Patient Safety Authority, the authority that informs nurses on issues that can affect patient safety and presents strategies they can easily integrate into practice. For more information on the authority, visit www.patientsafetyauthority.org. For the original article discussed in this column or for other articles on patient safety, click on “Patient Safety Advisories” and then “Advisory Library” in the left-hand navigation menu.
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n intravascular air embolism is a preventable hospital-acquired condition that can result in serious harm, including death. In 2002, the National Quality Forum released its first list of what it named “serious reportable events,” which included intravascular air embolism. In 2006, the list was updated and adopted by the Centers for Medicare and Medicaid Services (CMS) as part of the Inpatient Prospective Payment System, which took effect October 1, 2008, and a policy of nonpayment to hospitals for serious reportable events was instituted.1 Intravascular air embolism occurs when two conditions are met: there is a direct connection between a source of air and the vascular system, and the pressure gradient—the difference in pressure—favors the entry of that air into the bloodstream.2, 3 A central line, or even the tract left after central line removal, provides such a connection. Also, because most central lines terminate in the superior vena cava, where central venous pressure (CVP) is normally lower than atmospheric pressure, the pressure gradient favors the passive movement of air into the venous system if proper precautions are not taken. In other words, air will move from an area of higher pressure (outside the body) to an area of lower pressure (inside the central venous circulation) if a direct connection exists through which the air can move freely. The greater the gradient, the more quickly air will move to the area of lower pressure. The pressure gradient between the atmosphere and the central venous circulation is further increased as a result of negative intrathoracic pressure during the inspiratory phase of respiration and conditions that decrease CVP, such as hypovolemia 64
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or upright positioning of the patient. As a result, the volume of air necessary to be fatal in adults, 200 to 300 mL, can enter the bloodstream in a matter of seconds through a central line.4 The consequences of an air embolism depend on the amount of air entering the bloodstream, the rate at which it enters, and its route into the bloodstream (venous or arterial). Air introduced into the venous system travels to the right side of the heart and into the pulmonary vasculature, where smaller volumes of air can be dissipated, often without symptoms. When air is introduced more rapidly, or in larger volumes, pulmonary artery pressures rise, putting strain on the right side of the heart. In some cases, an air lock can form in one or more of the pulmonary arteries, obstructing pulmonary circulation and causing complete circulatory collapse. In general, the closer to the heart an air embolism is when it’s introduced into the venous system, the smaller the volume of air needs to be for the embolism to become symptomatic.2-4 The primary body systems affected by air embolisms are cardiovascular, pulmonary, and neurologic. The cardiovascular effects of air embolism include tachyarrhythmias and other electrocardiographic changes consistent with right-sided heart failure or myocardial ischemia, increased pulmonary artery pressures, increased CVP secondary to right-sided heart failure, and decreased cardiac output leading to hypotension and shock. Pulmonary effects include rales, wheezing, tachypnea, decreased end-tidal carbon dioxide levels, and decreased arterial oxygen saturation levels. Arterial blood gas analysis may reveal hypoxia and hypercapnia. In patients who are awake, ajnonline.com
By Michelle Feil, MSN, RN
symptoms reported may include dyspnea, continuous coughing, chest pain, breathlessness, and a sense of “impending doom.” Neurologic effects occur as a result of either hypoperfusion of the brain secondary to decreased cardiac output or the direct effects of air embolisms that have entered the cerebral circulation. Symptoms range from altered mental status to cerebral edema and coma.2-4 Apart from these cardiovascular, pulmonary, and neurologic effects, air embolisms, even when small, can cause tissue ischemia or inflammatory changes within blood vessels as they travel throughout the body, leading to a host of potentially lethal complications (such as systemic inflammatory response syndrome, pulmonary edema, and myocardial or cerebral ischemia).2-4 In contrast to venous air embolism, arterial air embolism is very poorly tolerated, and even a small amount of air can be lethal. Of particular concern, it’s estimated that 25% of people in the general population have a patent foramen ovale (PFO), an opening between the left and right atria that didn’t close during infancy as it should have. PFOs are usually asymptomatic and remain undetected.5 However, the presence of a PFO in the context of a venous air embolism is highly dangerous because it is a pathway through which the venous air embolism can quickly pass into the arterial circulation and enter the cerebral circulation (causing a stroke) or the coronary circulation (causing a myocardial infarction).2-4 The frequency of venous air embolisms related to central lines has been estimated at anywhere from one in 47 to one in 3,000.2, 3 Although they are infrequent, venous air embolisms carry mortality rates ranging from 23% to 50%.6, 7 The widespread use of central lines, both in hospitals and in community settings, warrants special attention, given the risk of air embolism associated with their use.
AIR EMBOLISM EVENT REPORTING IN PENNSYLVANIA
Between June 2004 and December 2011, Pennsylvania acute care facilities reported 74 events related to air embolisms to the Pennsylvania Patient Safety Authority: 41 confirmed instances of air embolism, 18 suspected instances of air embolism (in which the patient was symptomatic in the presence of known risk factors for air embolism without radiographic confirmation), and 15 events involving situations in which the patient was placed at high risk for developing an air embolism. Of the 59 confirmed or suspected air embolisms, 24 were associated with central lines (see Table 1); the next most common associated clinical contexts were surgical procedures, intravascular procedures, and peripheral venous access devices. [email protected]
Table 1. Reports to the Pennsylvania Patient Safety Authority of Confirmed or Suspected Central Line–Associated Air Embolisms, June 2004 Through December 2011 Contributing Factor
Number of Reports
Insertion Venous catheter placed in artery
2
Injection of air
1
Line exchange with head elevated
1
Lines not clamped or capped
1
No Valsalva maneuver
1
Not specified
3
Subtotal
9
Care and maintenance Contrast media injection
1
Other injection of air
1
Line not clamped or capped
1
Line mishandled by unlicensed staff
1
Subtotal
4
Removal by health care provider Head elevated during removal
6
Not specified
3
Subtotal
9
Removal by patient
1
No cause identified in report
1
Total
24
Analysis of the 24 reports of confirmed and suspected central line–associated air embolism revealed the following: • Eight events (33.3%) were reported as incidents in which no harm was caused to the patient. • Sixteen events (66.7%) were reported as serious events resulting in harm, including in some cases death. • Nine events (37.5%) were associated with central line insertion. • Four events (16.7%) were associated with the care and maintenance of central lines. • Nine events (37.5%) were associated with central line removal by a health care provider, and one event (4.2%) involved removal by a patient. • Central line removal while the head of the patient was elevated was indicated in six event reports AJN ▼ June 2015
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Figure 1. Air Embolism Reports to the Pennsylvania Patient Safety Authority by Quarter, June 2004 to December 2011
(25%), representing the most frequently reported contributing factor in air embolism formation.
EXAMPLES OF EVENT REPORTS
Despite the designation of air embolism as a serious reportable event worthy of nonpayment by the CMS—and with presumably more attention paid to prevention—event reports to the Pennsylvania Patient Safety Authority that are related to air embolism have increased over time (see Figure 1). Below are examples of events reported through the authority’s Pennsylvania Patient Safety Reporting System (PA-PSRS). • An interventional radiology resident came to the floor and removed the catheter while the patient was sitting semirecumbent in a chair. A gauze dressing, combined with an occlusive dressing, was placed over the access site. Not too long after that, another resident came in to visit the patient and noted [the patient] sitting in the chair, tachypneic and desaturated. The patient was moved to the ICU [because of] a possible air embolism. • A patient came to interventional radiology for a tunneled catheter placement. During the procedure, the patient got an air embolism. After talking to the physician, [it was determined that] the 66
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cause of the embolism [was] the catheter . . . being passed into the patient [without occlusion (for example, there were no caps, it wasn’t clamped, the lumen wasn’t covered by the thumb)]. The staff recognized vascular air entrainment immediately from the sucking sounds coming through the unoccluded catheter ports. The patient was . . . immediately . . . placed on his left side, and [oxygen was increased]. The patient was transferred back to the ICU with the ICU nurse and physician. The patient was monitored closely and needed no further treatments. • A patient was admitted with a stroke. The physician placed a subclavian central line. A follow-up chest X-ray was obtained. iv fluids were administered through the central line. The patient was taken for a CT [computed tomographic] scan of the head. During the CT scan, the physician was made aware by radiology that the central line was in the artery. The CT scan of the head showed intracranial air consistent with an air embolism. • A 10-day-old infant was admitted to the ICU. . . . She acutely developed bradycardia, mottling, and hypotension. She required multiple rounds of medications, including epinephrine, atropine, and sodium bicarbonate, as well as tracheal intubation and cardiac compressions. An echocardiogram ajnonline.com
performed during the resuscitation showed severely depressed myocardial function, no pericardial effusion, and what appeared to be echo-bright areas of the myocardium consistent with [a possible] air embolism. Following resuscitation, the infant returned to her previous cardiac baseline hemodynamics. The nurse caring for the child subsequently reported that approximately one half hour before the event, he had changed the iv fluid–administration tubing that was infusing into the patient’s umbilical venous catheter. The nurse reported that he had followed the hospital’s nursing procedure for iv-tubing change. • The patient’s caregiver disconnected the patient’s iv line from the central line so that the patient could [walk to] the bathroom. After returning to bed, the patient coded. After one minute of cardiopulmonary resuscitation and oxygen bagging, the patient began to respond. The patient was also placed in [the] Trendelenburg [position] and turned [because of] suspected air emboli. The patient was transferred to the ICU for further observation.
RECOGNIZING RISK
Historically, central line insertion—as opposed to removal—has received focused attention as a procedure with multiple serious risks, including air embolism formation. In fact, central line insertion has long been included in lists of procedural competencies required of resident physicians, whereas the care and maintenance and the removal of central lines have not.8, 9 Because of this, it has been suggested that the risk of air embolism formation during central line removal in particular has been underappreciated.10 In recent years, the care and maintenance of central lines have received renewed attention as part of prevention initiatives targeting central line– associated bloodstream infections; however, because these initiatives are focused on preventing infections, steps to prevent air embolism are not stressed in the procedural checklists developed as part of these programs. For instance, when positioning patients for central line insertion is mentioned, instructions can be vague (“position patient correctly for procedure” for example). Infusion nurses are one group of health care professionals that has established standards of practice calling for competency in central line insertion, management, and removal “toward the goal of preventing air emboli.”11, 12 The establishment of a team of infusion nurses with 100% ownership of the insertion and removal of central lines is an example of a process change that has been effective in reducing central line–associated complications in some hospitals.13 [email protected]
Peripherally Inserted Central Venous Catheter Line Removal A peripherally inserted central venous catheter (PICC) is classified as a central venous access device (CVAD) because its tip lies within a central vein, usually the superior vena cava, where venous pressure is typically lower than atmospheric pressure. This pressure gradient (difference) favors the ingress of air. However, the insertion–exit site for a PICC line is in a peripheral vein, where venous pressure is usually higher than atmospheric pressure. This pressure gradient favors the outflow of venous blood and not the ingress of air. If all precautions are taken to maintain a closed system during PICC line removal (in other words, all lumens are capped or clamped, as applicable), the potential for air ingress is minimal. Therefore, the methods recommended to prevent CVAD-associated air embolism apply to PICC line insertion, as well as to care and maintenance of the line. However, they do not apply to PICC line removal. To prevent air ingress when removing a peripheral iv catheter, the exit site needs to be lower than the heart. The same measures used for removing short peripheral iv catheters should be applied to PICCs.
PREVENTING AIR EMBOLISMS
Although uncommon, air embolisms can have serious adverse effects and are largely preventable through the application of evidence-based practices. The following practices have been recommended for prevention of air embolism during the three phases of central line care: insertion, care and maintenance, and removal.3, 4, 11, 12, 14-18 Insertion of central lines. • Take steps to increase CVP. Increasing CVP decreases the pressure gradient that would normally favor movement of air into the bloodstream. CVP is normally lower in all blood vessels located above the level of the heart and during inspiration. oo Place the patient in the Trendelenburg position with a downward tilt of 10° to 30° during central line placement. oo Avoid central line insertion during patient inspiration. Instruct the patient to hold her or his breath and, if able, perform a Valsalva maneuver. oo Hydrate the patient to correct hypovolemia prior to insertion whenever possible. • Ensure that all catheters and connections (especially in two-piece systems) are intact and secure. • Occlude the catheter and needle hub, as applicable. • Ensure that all self-sealing valves are functioning properly. Care and maintenance of central lines. • Ensure that all lumens are capped or clamped, as AJN ▼ June 2015
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applicable, when not connected to a continuous infusion. • Use Luer lock connections for needleless iv ports and self-sealing valves. • Use infusion pumps with air-in-line sensors for all continuous infusions. • Fully prime and expel air from all syringes and infusion tubing prior to any injection or infusion. • Use an air-eliminating filter on infusion tubing sets whenever appropriate. • Remove air from infusion bags when infusing fluids using inflatable pressure infusers. • Fully prime contrast medium injectors, and check for air prior to each injection. • Trace lines, double-check all connections, and take all steps necessary to prevent tubing misconnections. • Inspect the insertion site, catheter, and all connections regularly to assess for breaks or openings through which air could enter the system. • Ensure the integrity of the central line dressing surrounding the insertion site. • Use caution when moving or repositioning patients to prevent pulling on the central line. A break in the closed system, combined with decreased CVP (caused by movement of the patient to an upright position or deep inspiration), creates a high risk of air embolism. • Teach patients and caregivers managing infusion therapy how to perform all steps necessary to prevent air embolisms.
It’s important never to remove the central line while the patient is seated or upright. Removal of central lines (not including peripherally inserted central venous catheter [PICC] lines). • Take steps to increase CVP. It’s important never to remove the central line while the patient is seated or in the upright position, which causes blood to pool in the lower extremities, further decreasing CVP and creating a pressure gradient that favors the movement of air into the bloodstream. oo Place the patient in the Trendelenburg position when possible. If it’s not possible, the supine position is sufficient. oo Position the catheter exit site (at the neck or arm, for example) lower than the level of the patient’s heart. 68
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• Cover the exit site with gauze, and apply gentle pressure while removing the catheter in a slow, constant motion. • Instruct the patient to hold her or his breath and perform a Valsalva maneuver as the last portion of the catheter is removed; if the patient cannot do this, time the removal to coincide with an expiration. • Put pressure on the site until hemostasis is achieved; one to five minutes is suggested. • Apply a sterile occlusive dressing, such as gauze impregnated with petroleum jelly and covered with a transparent film dressing. Leave the dressing in place for at least 24 hours. Change the dressing every 24 hours until the exit site has healed. (Instances have been reported in which plain gauze dressings were used and air passed through a persistent catheter tract into the bloodstream, resulting in air embolisms; there have been similar reports involving occlusive dressings left in place for shorter periods of time.) • Instruct the patient to lie flat for 30 minutes after removal of the catheter.
TREATMENT OF A SUSPECTED AIR EMBOLISM
A high degree of suspicion for air embolism should be maintained when inserting, removing, or otherwise manipulating central lines. Although air embolisms are often asymptomatic, the following are clinical signs that may signal the presence of one: dyspnea, tachypnea, decreased oxygen saturation level, a “sense of impending doom,” anxiety, agitation, changes in mental status, chest pain, tachycardia or bradycardia, hypotension, pallor, and light-headedness. If the patient is being monitored with capnography during the insertion, a decreased or an erratic end-tidal carbon dioxide level may indicate an air embolism. Emergency management of a suspected air embolism includes preventing the further entry of air, placing the patient in the Trendelenburg position (and lying on the left side), and administering 100% ox ygen. This position helps the air embolism to move toward the apex of the right ventricle, away from the pulmonary artery and right ventricular outflow tract. The administration of oxygen supports a patient with cardiovascular instability or collapse and helps decrease the size of the air embolism through its effects on the partial pressures of oxygen and nitrogen within the blood, which cause nitrogen to move from the embolism into the bloodstream.3, 4, 14, 15, 18 In ventilated patients, the use of moderate levels of positive end-expiratory pressure (PEEP) can help improve oxygenation and prevent the further entrainment of air. However, caution must be used because PEEP has also been associated with an increased risk ajnonline.com
of air embolism formation related to either an associated drop in CVP or direct barotrauma causing air from the pulmonary system to be pushed into the vasculature.4, 18 Withdrawing the air through the central line may be beneficial in some cases if it can be done. Hemodynamic support should be provided with inotropic drugs and fluid resuscitation to increase CVP. Cardiopulmonary resuscitation or intubation (or both) may be necessary. Chest compressions may have the added benefit of helping to break up air emboli and move them away from the right ventricular outflow tract. Once the patient is stabilized, hyperbaric oxygen therapy can mitigate further effects of air emboli and decrease their size.3, 4, 18
HOSPITAL RISK-REDUCTION STRATEGIES
Hospitals can take the following measures to reduce the risk of air embolism associated with central lines.11, 13, 15, 17-19 • Establish hospital policies and procedures that contain specific air embolism–prevention protocols for central line insertion, management, and removal. • Ensure that practitioners inserting and removing central lines have had adequate training and experience in performing the procedures. • Consider the use of a standardized insertion bundle kit or cart and a standardized removal kit. • Provide all nurses and other clinical staff handling central lines with ongoing training in proper line care, and assess staff for competence. Reassess competence annually. • Consider establishing a vascular access nurse team with 100% ownership of placement, assessment, and removal of nontunneled, short-term central venous access catheters, including PICC lines. • Do not purchase nonintravenous equipment that can be connected to needleless iv ports. • Use equipment with safety features designed to prevent air embolism (such as vascular access catheters and caps with self-sealing or one-way valves, infusion pumps with air-in-line detection, and infusion tubing with in-line filters). • Instruct nonclinical staff, patients, and family members to ask a clinician to assist whenever a central line needs to be disconnected or reconnected.
PREVENTION, FROM BEGINNING TO END
Air embolism is an infrequent but potentially lethal complication of central line use. Analysis of air embolism reports to PA-PSRS suggests that hospitals need to take steps to prevent air embolism formation during all phases of central line care, from insertion through removal. The implementation of specific evidence-based prevention measures, along [email protected]
with risk-reduction strategies, can significantly decrease the frequency of, or even eliminate, this serious event. ▼ Michelle Feil is a senior patient safety analyst at the Pennsylvania Patient Safety Authority in Plymouth Meeting, PA. This article is adapted from “Reducing Risk of Air Embolism Associated with Central Venous Access Devices,” which appeared in a publication of the Pennsylvania Patient Safety Authority: Pennsylvania Patient Safety Advisory 2012;9(2):58-64. Contact author: [email protected]. The author has disclosed no potential conflicts of interest, financial or otherwise.
REFERENCES 1. Department of Health and Human Services, Centers for Medicare and Medicaid Services. Medicare program: listening session on hospital-acquired conditions in inpatient settings and hospital outpatient healthcare-associated conditions in outpatient settings, December 18, 2008. Federal Register 2008;73(211):64618-19. https://www.cms.gov/Medicare/ Medicare-Fee-for-Service-Payment/HospitalAcqCond/ downloads/1422_N_FEDERAL_REGISTER_VERSION_ PUB_10_30_08_508.pdf. 2. Natal BL. Venous air embolism. Medscape 2012. http:// emedicine.medscape.com/article/761367-overview. 3. O’Dowd LC, Kelley MA. Air embolism. UpToDate 2013. http://www.uptodate.com/contents/air-embolism. 4. Mirski MA, et al. Diagnosis and treatment of vascular air embolism. Anesthesiology 2007;106(1):164-77. 5. Cleveland Clinic. Patent foramen ovale (PFO). 2012. http:// my.clevelandclinic.org/services/heart/disorders/congenital/pfo. 6. Kashuk JL, Penn I. Air embolism after central venous catheterization. Surg Gynecol Obstet 1984;159(3):249-52. 7. Heckmann JG, et al. Neurologic manifestations of cerebral air embolism as a complication of central venous catheterization. Crit Care Med 2000;28(5):1621-5. 8. Surgical Council on Resident Education. SCORE curriculum outline for general surgery residency 2014-2015. Phildelphia; 2014. http://www.absurgery.org/xfer/curriculumoutline2014-15. pdf. 9. American Board of Internal Medicine. Internal medicine policies: procedures required for internal medicine certification n.d. http://www.abim.org/certification/policies/imss/im.aspx. 10. Kim DK, et al. The CVC removal distress syndrome: an unappreciated complication of central venous catheter removal. Am Surg 1998;64(4):344-7. 11. Infusion Nurses Society. Infusion nursing standards of practice. J Infus Nurs 2011;34(1S). 12. Infusion Nurses Society. Policies and procedures for infusion nursing. 4th ed. Norwood, MA: The Society; 2011. 13. Rosenthal K. Targeting “never events.” Nurs Manage 2008; 39(12):35-8. 14. Drewett SR. Central venous catheter removal: procedures and rationale. Br J Nurs 2000;9(22):2304-15. 15. Ingram P, et al. The safe removal of central venous catheters. Nurs Stand 2006;20(49):42-6. 16. Brockmeyer J, et al. Cerebral air embolism following removal of central venous catheter. Mil Med 2009;174(8):878-81. 17. [no author.] Tubing misconnections: making the connection to patient safety. Pennsylvania Patient Safety Advisory 2010;7(2):41-5. http://patientsafetyauthority.org/ADVISORIES/AdvisoryLibrary/2010/Jun7(2)/Pages/Home.aspx. 18. Joint Commission Resources. Clinical care improvement strategies: preventing air embolism. Oakbrook Terrace, IL; 2010. Clinical care improvement strategies. 19. McGee DC, Gould MK. Preventing complications of central venous catheterization. N Engl J Med 2003;348(12):1123-33.
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Preventing Central Line Air Embolism Recommended practices for central line insertion, management, and removal. The Pennsylvania Patient Safety Reporting System is a confidential, statewide Internet reporting system to which all Pennsylvania hospitals, outpatient-surgery facilities, birthing centers, and abortion facilities must file information on incidents and serious events. Safety Monitor is a column from Pennsylvania’s Patient Safety Authority, the authority that informs nurses on issues that can affect patient safety and presents strategies they can easily integrate into practice. For more information on the authority, visit www.patientsafetyauthority.org. For the original article discussed in this column or for other articles on patient safety, click on “Patient Safety Advisories” and then “Advisory Library” in the left-hand navigation menu.
A
n intravascular air embolism is a preventable hospital-acquired condition that can result in serious harm, including death. In 2002, the National Quality Forum released its first list of what it named “serious reportable events,” which included intravascular air embolism. In 2006, the list was updated and adopted by the Centers for Medicare and Medicaid Services (CMS) as part of the Inpatient Prospective Payment System, which took effect October 1, 2008, and a policy of nonpayment to hospitals for serious reportable events was instituted.1 Intravascular air embolism occurs when two conditions are met: there is a direct connection between a source of air and the vascular system, and the pressure gradient—the difference in pressure—favors the entry of that air into the bloodstream.2, 3 A central line, or even the tract left after central line removal, provides such a connection. Also, because most central lines terminate in the superior vena cava, where central venous pressure (CVP) is normally lower than atmospheric pressure, the pressure gradient favors the passive movement of air into the venous system if proper precautions are not taken. In other words, air will move from an area of higher pressure (outside the body) to an area of lower pressure (inside the central venous circulation) if a direct connection exists through which the air can move freely. The greater the gradient, the more quickly air will move to the area of lower pressure. The pressure gradient between the atmosphere and the central venous circulation is further increased as a result of negative intrathoracic pressure during the inspiratory phase of respiration and conditions that decrease CVP, such as hypovolemia 64
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or upright positioning of the patient. As a result, the volume of air necessary to be fatal in adults, 200 to 300 mL, can enter the bloodstream in a matter of seconds through a central line.4 The consequences of an air embolism depend on the amount of air entering the bloodstream, the rate at which it enters, and its route into the bloodstream (venous or arterial). Air introduced into the venous system travels to the right side of the heart and into the pulmonary vasculature, where smaller volumes of air can be dissipated, often without symptoms. When air is introduced more rapidly, or in larger volumes, pulmonary artery pressures rise, putting strain on the right side of the heart. In some cases, an air lock can form in one or more of the pulmonary arteries, obstructing pulmonary circulation and causing complete circulatory collapse. In general, the closer to the heart an air embolism is when it’s introduced into the venous system, the smaller the volume of air needs to be for the embolism to become symptomatic.2-4 The primary body systems affected by air embolisms are cardiovascular, pulmonary, and neurologic. The cardiovascular effects of air embolism include tachyarrhythmias and other electrocardiographic changes consistent with right-sided heart failure or myocardial ischemia, increased pulmonary artery pressures, increased CVP secondary to right-sided heart failure, and decreased cardiac output leading to hypotension and shock. Pulmonary effects include rales, wheezing, tachypnea, decreased end-tidal carbon dioxide levels, and decreased arterial oxygen saturation levels. Arterial blood gas analysis may reveal hypoxia and hypercapnia. In patients who are awake, ajnonline.com
By Michelle Feil, MSN, RN
symptoms reported may include dyspnea, continuous coughing, chest pain, breathlessness, and a sense of “impending doom.” Neurologic effects occur as a result of either hypoperfusion of the brain secondary to decreased cardiac output or the direct effects of air embolisms that have entered the cerebral circulation. Symptoms range from altered mental status to cerebral edema and coma.2-4 Apart from these cardiovascular, pulmonary, and neurologic effects, air embolisms, even when small, can cause tissue ischemia or inflammatory changes within blood vessels as they travel throughout the body, leading to a host of potentially lethal complications (such as systemic inflammatory response syndrome, pulmonary edema, and myocardial or cerebral ischemia).2-4 In contrast to venous air embolism, arterial air embolism is very poorly tolerated, and even a small amount of air can be lethal. Of particular concern, it’s estimated that 25% of people in the general population have a patent foramen ovale (PFO), an opening between the left and right atria that didn’t close during infancy as it should have. PFOs are usually asymptomatic and remain undetected.5 However, the presence of a PFO in the context of a venous air embolism is highly dangerous because it is a pathway through which the venous air embolism can quickly pass into the arterial circulation and enter the cerebral circulation (causing a stroke) or the coronary circulation (causing a myocardial infarction).2-4 The frequency of venous air embolisms related to central lines has been estimated at anywhere from one in 47 to one in 3,000.2, 3 Although they are infrequent, venous air embolisms carry mortality rates ranging from 23% to 50%.6, 7 The widespread use of central lines, both in hospitals and in community settings, warrants special attention, given the risk of air embolism associated with their use.
AIR EMBOLISM EVENT REPORTING IN PENNSYLVANIA
Between June 2004 and December 2011, Pennsylvania acute care facilities reported 74 events related to air embolisms to the Pennsylvania Patient Safety Authority: 41 confirmed instances of air embolism, 18 suspected instances of air embolism (in which the patient was symptomatic in the presence of known risk factors for air embolism without radiographic confirmation), and 15 events involving situations in which the patient was placed at high risk for developing an air embolism. Of the 59 confirmed or suspected air embolisms, 24 were associated with central lines (see Table 1); the next most common associated clinical contexts were surgical procedures, intravascular procedures, and peripheral venous access devices. [email protected]
Table 1. Reports to the Pennsylvania Patient Safety Authority of Confirmed or Suspected Central Line–Associated Air Embolisms, June 2004 Through December 2011 Contributing Factor
Number of Reports
Insertion Venous catheter placed in artery
2
Injection of air
1
Line exchange with head elevated
1
Lines not clamped or capped
1
No Valsalva maneuver
1
Not specified
3
Subtotal
9
Care and maintenance Contrast media injection
1
Other injection of air
1
Line not clamped or capped
1
Line mishandled by unlicensed staff
1
Subtotal
4
Removal by health care provider Head elevated during removal
6
Not specified
3
Subtotal
9
Removal by patient
1
No cause identified in report
1
Total
24
Analysis of the 24 reports of confirmed and suspected central line–associated air embolism revealed the following: • Eight events (33.3%) were reported as incidents in which no harm was caused to the patient. • Sixteen events (66.7%) were reported as serious events resulting in harm, including in some cases death. • Nine events (37.5%) were associated with central line insertion. • Four events (16.7%) were associated with the care and maintenance of central lines. • Nine events (37.5%) were associated with central line removal by a health care provider, and one event (4.2%) involved removal by a patient. • Central line removal while the head of the patient was elevated was indicated in six event reports AJN ▼ June 2015
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Figure 1. Air Embolism Reports to the Pennsylvania Patient Safety Authority by Quarter, June 2004 to December 2011
(25%), representing the most frequently reported contributing factor in air embolism formation.
EXAMPLES OF EVENT REPORTS
Despite the designation of air embolism as a serious reportable event worthy of nonpayment by the CMS—and with presumably more attention paid to prevention—event reports to the Pennsylvania Patient Safety Authority that are related to air embolism have increased over time (see Figure 1). Below are examples of events reported through the authority’s Pennsylvania Patient Safety Reporting System (PA-PSRS). • An interventional radiology resident came to the floor and removed the catheter while the patient was sitting semirecumbent in a chair. A gauze dressing, combined with an occlusive dressing, was placed over the access site. Not too long after that, another resident came in to visit the patient and noted [the patient] sitting in the chair, tachypneic and desaturated. The patient was moved to the ICU [because of] a possible air embolism. • A patient came to interventional radiology for a tunneled catheter placement. During the procedure, the patient got an air embolism. After talking to the physician, [it was determined that] the 66
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cause of the embolism [was] the catheter . . . being passed into the patient [without occlusion (for example, there were no caps, it wasn’t clamped, the lumen wasn’t covered by the thumb)]. The staff recognized vascular air entrainment immediately from the sucking sounds coming through the unoccluded catheter ports. The patient was . . . immediately . . . placed on his left side, and [oxygen was increased]. The patient was transferred back to the ICU with the ICU nurse and physician. The patient was monitored closely and needed no further treatments. • A patient was admitted with a stroke. The physician placed a subclavian central line. A follow-up chest X-ray was obtained. iv fluids were administered through the central line. The patient was taken for a CT [computed tomographic] scan of the head. During the CT scan, the physician was made aware by radiology that the central line was in the artery. The CT scan of the head showed intracranial air consistent with an air embolism. • A 10-day-old infant was admitted to the ICU. . . . She acutely developed bradycardia, mottling, and hypotension. She required multiple rounds of medications, including epinephrine, atropine, and sodium bicarbonate, as well as tracheal intubation and cardiac compressions. An echocardiogram ajnonline.com
performed during the resuscitation showed severely depressed myocardial function, no pericardial effusion, and what appeared to be echo-bright areas of the myocardium consistent with [a possible] air embolism. Following resuscitation, the infant returned to her previous cardiac baseline hemodynamics. The nurse caring for the child subsequently reported that approximately one half hour before the event, he had changed the iv fluid–administration tubing that was infusing into the patient’s umbilical venous catheter. The nurse reported that he had followed the hospital’s nursing procedure for iv-tubing change. • The patient’s caregiver disconnected the patient’s iv line from the central line so that the patient could [walk to] the bathroom. After returning to bed, the patient coded. After one minute of cardiopulmonary resuscitation and oxygen bagging, the patient began to respond. The patient was also placed in [the] Trendelenburg [position] and turned [because of] suspected air emboli. The patient was transferred to the ICU for further observation.
RECOGNIZING RISK
Historically, central line insertion—as opposed to removal—has received focused attention as a procedure with multiple serious risks, including air embolism formation. In fact, central line insertion has long been included in lists of procedural competencies required of resident physicians, whereas the care and maintenance and the removal of central lines have not.8, 9 Because of this, it has been suggested that the risk of air embolism formation during central line removal in particular has been underappreciated.10 In recent years, the care and maintenance of central lines have received renewed attention as part of prevention initiatives targeting central line– associated bloodstream infections; however, because these initiatives are focused on preventing infections, steps to prevent air embolism are not stressed in the procedural checklists developed as part of these programs. For instance, when positioning patients for central line insertion is mentioned, instructions can be vague (“position patient correctly for procedure” for example). Infusion nurses are one group of health care professionals that has established standards of practice calling for competency in central line insertion, management, and removal “toward the goal of preventing air emboli.”11, 12 The establishment of a team of infusion nurses with 100% ownership of the insertion and removal of central lines is an example of a process change that has been effective in reducing central line–associated complications in some hospitals.13 [email protected]
Peripherally Inserted Central Venous Catheter Line Removal A peripherally inserted central venous catheter (PICC) is classified as a central venous access device (CVAD) because its tip lies within a central vein, usually the superior vena cava, where venous pressure is typically lower than atmospheric pressure. This pressure gradient (difference) favors the ingress of air. However, the insertion–exit site for a PICC line is in a peripheral vein, where venous pressure is usually higher than atmospheric pressure. This pressure gradient favors the outflow of venous blood and not the ingress of air. If all precautions are taken to maintain a closed system during PICC line removal (in other words, all lumens are capped or clamped, as applicable), the potential for air ingress is minimal. Therefore, the methods recommended to prevent CVAD-associated air embolism apply to PICC line insertion, as well as to care and maintenance of the line. However, they do not apply to PICC line removal. To prevent air ingress when removing a peripheral iv catheter, the exit site needs to be lower than the heart. The same measures used for removing short peripheral iv catheters should be applied to PICCs.
PREVENTING AIR EMBOLISMS
Although uncommon, air embolisms can have serious adverse effects and are largely preventable through the application of evidence-based practices. The following practices have been recommended for prevention of air embolism during the three phases of central line care: insertion, care and maintenance, and removal.3, 4, 11, 12, 14-18 Insertion of central lines. • Take steps to increase CVP. Increasing CVP decreases the pressure gradient that would normally favor movement of air into the bloodstream. CVP is normally lower in all blood vessels located above the level of the heart and during inspiration. oo Place the patient in the Trendelenburg position with a downward tilt of 10° to 30° during central line placement. oo Avoid central line insertion during patient inspiration. Instruct the patient to hold her or his breath and, if able, perform a Valsalva maneuver. oo Hydrate the patient to correct hypovolemia prior to insertion whenever possible. • Ensure that all catheters and connections (especially in two-piece systems) are intact and secure. • Occlude the catheter and needle hub, as applicable. • Ensure that all self-sealing valves are functioning properly. Care and maintenance of central lines. • Ensure that all lumens are capped or clamped, as AJN ▼ June 2015
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applicable, when not connected to a continuous infusion. • Use Luer lock connections for needleless iv ports and self-sealing valves. • Use infusion pumps with air-in-line sensors for all continuous infusions. • Fully prime and expel air from all syringes and infusion tubing prior to any injection or infusion. • Use an air-eliminating filter on infusion tubing sets whenever appropriate. • Remove air from infusion bags when infusing fluids using inflatable pressure infusers. • Fully prime contrast medium injectors, and check for air prior to each injection. • Trace lines, double-check all connections, and take all steps necessary to prevent tubing misconnections. • Inspect the insertion site, catheter, and all connections regularly to assess for breaks or openings through which air could enter the system. • Ensure the integrity of the central line dressing surrounding the insertion site. • Use caution when moving or repositioning patients to prevent pulling on the central line. A break in the closed system, combined with decreased CVP (caused by movement of the patient to an upright position or deep inspiration), creates a high risk of air embolism. • Teach patients and caregivers managing infusion therapy how to perform all steps necessary to prevent air embolisms.
It’s important never to remove the central line while the patient is seated or upright. Removal of central lines (not including peripherally inserted central venous catheter [PICC] lines). • Take steps to increase CVP. It’s important never to remove the central line while the patient is seated or in the upright position, which causes blood to pool in the lower extremities, further decreasing CVP and creating a pressure gradient that favors the movement of air into the bloodstream. oo Place the patient in the Trendelenburg position when possible. If it’s not possible, the supine position is sufficient. oo Position the catheter exit site (at the neck or arm, for example) lower than the level of the patient’s heart. 68
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• Cover the exit site with gauze, and apply gentle pressure while removing the catheter in a slow, constant motion. • Instruct the patient to hold her or his breath and perform a Valsalva maneuver as the last portion of the catheter is removed; if the patient cannot do this, time the removal to coincide with an expiration. • Put pressure on the site until hemostasis is achieved; one to five minutes is suggested. • Apply a sterile occlusive dressing, such as gauze impregnated with petroleum jelly and covered with a transparent film dressing. Leave the dressing in place for at least 24 hours. Change the dressing every 24 hours until the exit site has healed. (Instances have been reported in which plain gauze dressings were used and air passed through a persistent catheter tract into the bloodstream, resulting in air embolisms; there have been similar reports involving occlusive dressings left in place for shorter periods of time.) • Instruct the patient to lie flat for 30 minutes after removal of the catheter.
TREATMENT OF A SUSPECTED AIR EMBOLISM
A high degree of suspicion for air embolism should be maintained when inserting, removing, or otherwise manipulating central lines. Although air embolisms are often asymptomatic, the following are clinical signs that may signal the presence of one: dyspnea, tachypnea, decreased oxygen saturation level, a “sense of impending doom,” anxiety, agitation, changes in mental status, chest pain, tachycardia or bradycardia, hypotension, pallor, and light-headedness. If the patient is being monitored with capnography during the insertion, a decreased or an erratic end-tidal carbon dioxide level may indicate an air embolism. Emergency management of a suspected air embolism includes preventing the further entry of air, placing the patient in the Trendelenburg position (and lying on the left side), and administering 100% ox ygen. This position helps the air embolism to move toward the apex of the right ventricle, away from the pulmonary artery and right ventricular outflow tract. The administration of oxygen supports a patient with cardiovascular instability or collapse and helps decrease the size of the air embolism through its effects on the partial pressures of oxygen and nitrogen within the blood, which cause nitrogen to move from the embolism into the bloodstream.3, 4, 14, 15, 18 In ventilated patients, the use of moderate levels of positive end-expiratory pressure (PEEP) can help improve oxygenation and prevent the further entrainment of air. However, caution must be used because PEEP has also been associated with an increased risk ajnonline.com
of air embolism formation related to either an associated drop in CVP or direct barotrauma causing air from the pulmonary system to be pushed into the vasculature.4, 18 Withdrawing the air through the central line may be beneficial in some cases if it can be done. Hemodynamic support should be provided with inotropic drugs and fluid resuscitation to increase CVP. Cardiopulmonary resuscitation or intubation (or both) may be necessary. Chest compressions may have the added benefit of helping to break up air emboli and move them away from the right ventricular outflow tract. Once the patient is stabilized, hyperbaric oxygen therapy can mitigate further effects of air emboli and decrease their size.3, 4, 18
HOSPITAL RISK-REDUCTION STRATEGIES
Hospitals can take the following measures to reduce the risk of air embolism associated with central lines.11, 13, 15, 17-19 • Establish hospital policies and procedures that contain specific air embolism–prevention protocols for central line insertion, management, and removal. • Ensure that practitioners inserting and removing central lines have had adequate training and experience in performing the procedures. • Consider the use of a standardized insertion bundle kit or cart and a standardized removal kit. • Provide all nurses and other clinical staff handling central lines with ongoing training in proper line care, and assess staff for competence. Reassess competence annually. • Consider establishing a vascular access nurse team with 100% ownership of placement, assessment, and removal of nontunneled, short-term central venous access catheters, including PICC lines. • Do not purchase nonintravenous equipment that can be connected to needleless iv ports. • Use equipment with safety features designed to prevent air embolism (such as vascular access catheters and caps with self-sealing or one-way valves, infusion pumps with air-in-line detection, and infusion tubing with in-line filters). • Instruct nonclinical staff, patients, and family members to ask a clinician to assist whenever a central line needs to be disconnected or reconnected.
PREVENTION, FROM BEGINNING TO END
Air embolism is an infrequent but potentially lethal complication of central line use. Analysis of air embolism reports to PA-PSRS suggests that hospitals need to take steps to prevent air embolism formation during all phases of central line care, from insertion through removal. The implementation of specific evidence-based prevention measures, along [email protected]
with risk-reduction strategies, can significantly decrease the frequency of, or even eliminate, this serious event. ▼ Michelle Feil is a senior patient safety analyst at the Pennsylvania Patient Safety Authority in Plymouth Meeting, PA. This article is adapted from “Reducing Risk of Air Embolism Associated with Central Venous Access Devices,” which appeared in a publication of the Pennsylvania Patient Safety Authority: Pennsylvania Patient Safety Advisory 2012;9(2):58-64. Contact author: [email protected]. The author has disclosed no potential conflicts of interest, financial or otherwise.
REFERENCES 1. Department of Health and Human Services, Centers for Medicare and Medicaid Services. Medicare program: listening session on hospital-acquired conditions in inpatient settings and hospital outpatient healthcare-associated conditions in outpatient settings, December 18, 2008. Federal Register 2008;73(211):64618-19. https://www.cms.gov/Medicare/ Medicare-Fee-for-Service-Payment/HospitalAcqCond/ downloads/1422_N_FEDERAL_REGISTER_VERSION_ PUB_10_30_08_508.pdf. 2. Natal BL. Venous air embolism. Medscape 2012. http:// emedicine.medscape.com/article/761367-overview. 3. O’Dowd LC, Kelley MA. Air embolism. UpToDate 2013. http://www.uptodate.com/contents/air-embolism. 4. Mirski MA, et al. Diagnosis and treatment of vascular air embolism. Anesthesiology 2007;106(1):164-77. 5. Cleveland Clinic. Patent foramen ovale (PFO). 2012. http:// my.clevelandclinic.org/services/heart/disorders/congenital/pfo. 6. Kashuk JL, Penn I. Air embolism after central venous catheterization. Surg Gynecol Obstet 1984;159(3):249-52. 7. Heckmann JG, et al. Neurologic manifestations of cerebral air embolism as a complication of central venous catheterization. Crit Care Med 2000;28(5):1621-5. 8. Surgical Council on Resident Education. SCORE curriculum outline for general surgery residency 2014-2015. Phildelphia; 2014. http://www.absurgery.org/xfer/curriculumoutline2014-15. pdf. 9. American Board of Internal Medicine. Internal medicine policies: procedures required for internal medicine certification n.d. http://www.abim.org/certification/policies/imss/im.aspx. 10. Kim DK, et al. The CVC removal distress syndrome: an unappreciated complication of central venous catheter removal. Am Surg 1998;64(4):344-7. 11. Infusion Nurses Society. Infusion nursing standards of practice. J Infus Nurs 2011;34(1S). 12. Infusion Nurses Society. Policies and procedures for infusion nursing. 4th ed. Norwood, MA: The Society; 2011. 13. Rosenthal K. Targeting “never events.” Nurs Manage 2008; 39(12):35-8. 14. Drewett SR. Central venous catheter removal: procedures and rationale. Br J Nurs 2000;9(22):2304-15. 15. Ingram P, et al. The safe removal of central venous catheters. Nurs Stand 2006;20(49):42-6. 16. Brockmeyer J, et al. Cerebral air embolism following removal of central venous catheter. Mil Med 2009;174(8):878-81. 17. [no author.] Tubing misconnections: making the connection to patient safety. Pennsylvania Patient Safety Advisory 2010;7(2):41-5. http://patientsafetyauthority.org/ADVISORIES/AdvisoryLibrary/2010/Jun7(2)/Pages/Home.aspx. 18. Joint Commission Resources. Clinical care improvement strategies: preventing air embolism. Oakbrook Terrace, IL; 2010. Clinical care improvement strategies. 19. McGee DC, Gould MK. Preventing complications of central venous catheterization. N Engl J Med 2003;348(12):1123-33.
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