Patient Safety Advisory Reprinted from the PA-PSRS Patient Safety Advisory—Vol. 1, No.4 (December 2004) Produced by ECRI & ISMP under contract to the Pennsylvania Patient Safety Authority Venous Air Emboli and Automatic Contrast Media Injectors Several reports have been submitted to PA-PSRS in emboli may obstruct the outflow from the right ven- which intravascular air emboli occurred with the use tricle or block pulmonary arterioles.2,8 of automatic contrast media injectors during CT scans. One report indicates that the patient became The severity of symptoms resulting from air embo- diaphoretic and was transferred to an intensive care lism is dependent upon such factors as the volume environment after undergoing a CT scan with con- of air injected and the speed of the injection.1,2 The trast. In this case, the patient was prepared for the position of the body at the time of air entry and the CT scan, but the empty contrast syringe from a pre- patient’s state of health also affect the outcome.1 vious case had not been removed from the injector. The automatic injector injected 25cc of air into the Certain medical conditions may allow a venous air patient. embolism to enter the arterial circulation, increasing the risk.1,8 Such conditions may include atrial or Small and moderate-sized air emboli are estimated ventricular septal defects and those with arterioven- to occur in 12% to 23% of patients undergoing con- ous malformation.1,2 Approximately 25% to 35% of trast-enhanced CT examination.1,2 Most of these air the general population with otherwise normal hearts emboli are undetected because patients are asymp- retain a patent foramen ovale, which could allow a tomatic,2 and the air is absorbed without difficulty. venous air embolism that reaches the heart to cross However, larger air emboli have been reported as a over into the arterial circulation. This is significant complication of pressure injection of contrast mate- because an air embolus as small as 1 ml in the ar- rial during CT scans.2 In contrast-enhanced imag- terial circulation may travel to the brain or coronary ing, venous air emboli are more common than those arteries, causing significant blockage.5 in the arterial vasculature.2 Though increased mor- bidity and mortality is more likely to be associated While most air emboli associated with the use of with arterial air emboli, significant consequences intravenous contrast media are asymptomatic, the can result from venous air injection, such as cardiac clinical literature reports numerous symptoms that and/or respiratory arrest, seizures, and neurological can indicate this complication (see Table 1). Most deficits.1 Accidental venous injection of air may pro- significantly, a patient may have a reflexive gasp duce a fatal air embolism.3 following an infusion of air into the pulmonary circu- lation. The gasp causes decreased intrathoracic Three elements must be present in order for air to and central venous pressure, which allows a larger be admitted into the vascular system: 1) a source of volume of air to enter any patent opening into a air (the atmosphere); 2) a connection between the vein, potentially contributing to sufficient volume to vascular system and the air source; and 3) a pres- cause cardiopulmonary collapse.4 Cardiovascular sure gradient that favors air entry.4 Air can enter an changes are generally associated with the size of open blood vessel when either of the following con- the air infusion. Small air infusions are associated ditions exist: 1) a negative intravascular pressure with a moderate decrease in blood pressure, while relative to air pressure; or 2) the air is under pres- larger air infusions may result in a further decrease sure and is pushed into vessels with or without a in blood pressure due to decreased cardiac output. negative intravascular pressure.4-6 The use of auto- matic contrast injectors meets this second condition. Air can also be introduced into the vascular system This article is reprinted from the PA-PSRS Patient Safety Advisory, Vol. 1, No. during contrast administration during cannula inser- 4—December 2004. The Advisory is a publication of the Pennsylvania Patient Safety Authority, produced by ECRI & ISMP under contract to the Authority as tion, when connecting the cannula to the injector part of the Pennsylvania Patient Safety Reporting System (PA-PSRS). tube, and through microbubbles in the contrast.7 Copyright 2004 by the Patient Safety Authority. This publication may be re- Once air enters the venous circulation, it moves to- printed and distributed without restriction, provided it is printed or distributed in ward the right atrium and then to the right ventricle. its entirety and without alteration. Individual articles may be reprinted in their entirety and without alteration provided the source is clearly attributed. From there, emboli usually travel via the pulmonary artery to the lungs. Small emboli are usually ab- To see other articles or issues of the Advisory, visit our web site at sorbed in the blood or alveoli of the lungs. Larger www.psa.state.pa.us. Click on “Advisories” in the left-hand menu bar. ©2004 Pennsylvania Patient Safety Authority Page 1 Reprinted from the PA-PSRS Patient Safety Advisory—Vol. 1, No. 4 (December 2004) Venous Air Emboli and Automatic Contrast Media Injectors (Continued) A large air infusion may create an air lock in the The procedure was not specified in 38% of pulmonary artery causing the blood pressure to these reports. Arterial procedures were docu- drop abruptly, followed by cardiovascular col- mented in 46% of the reports. In two reports, lapse. The outcome may be permanent neuro- the venous circulation was accessed by a logical damage or death.5 power injector. Patient outcomes of these events include death (cited in 54% of reports), The most specific and sensitive methodologies serious injury (15%), and aggressive interven- used to diagnose this complication are transe- tion/life threatening situations (31%). Event sophageal echocardiography and Doppler ultra- descriptions from these resources may shed sonography.1,2,9 Contrast-enhanced CT of the light on possible factors contributing to this compli- chest can also identify intravascular air emboli. cation: Plain chest radiographs have occasionally iden- tified air emboli but are less sensitive.4 In me- • The patient died after being injected with air chanically ventilated patients, this complication from an empty contrast media syringe that is associated with a reduction in the monitored was thought to be full. The empty syringe was end-tidal carbon dioxide level.2 not removed from the injector after a proce- dure. If symptomatic venous air embolism occurs, the • The technologist thought there was contrast in following interventions may help to minimize the syringe because of the placement of the harm: syringe in the pressure jacket. Air was injected into the patient. • Identifying the source of air entry and pre- venting further air entry into the venous cir- • The first contrast injection was completed culation.4,8 successfully. The catheter was disconnected • Placing the patient in the Durant position from the connector tubing to reload the sy- (the left lateral decubitus and Trendelenburg ringe. The technologist used the connector positions). This position may float air back tube connected to the syringe for reloading. out of the pulmonary vasculature and re- During reloading, the technologist noticed an lieve the airlock blocking the outflow of the air bubble in the syringe. The technologist heart.1,2,9 expelled the air from the syringe with the in- jector head in the downward position. The • When air is in the right atrium, central multi- technologist proceeded to make the cathe- orifice central venous catheters have been ter/connector tube connection and set the used to aspirate the air.4 A pulmonary artery injector for the second injection. The injection catheter has been used to aspirate air from was begun but was aborted when the physi- the right atrium and ventricle as the catheter cian could not see contrast coming out the is withdrawn from the pulmonary artery.2,9 catheter. The injector was reset and injection • Observing patients in an intensive care set- was completed. Expelling air from the syringe ting and monitoring progress through such with the injector head in the downward posi- diagnostic modalities as serial EKGs, car- tion is not consistent with the recommended diac biomarkers, coagulation studies, ABGs, procedure in the operator’s manual. and repeat imaging procedures.1,9 Where documented in the above reports, as well • Hyperbaric oxygen therapy may also reduce as in reports to PA-PSRS, the automatic injectors the size of the embolus and may benefit were found to have functioned properly. However, patients with cardiac or cerebral symp- there are several things that can be done to ad- toms.1,2,9 dress the risk of this complication, which may help A review was conducted of the FDA’s Manufac- reduce the potential for user error: turer and User Facility Device Experience (MAUDE) database, the FDA’s Center for De- Education vices and Radiological Health’s Medical Device • Limiting use of contrast media injectors to Reporting (MDR) database, and ECRI’s Health those with adequate training and those famil- Devices Alerts, pertaining to automatic contrast iar with current operating procedures as well injectors and air emboli. Since 1985, 13 occur- as risks associated with injection of air.1,3 rences have been reported to these resources. Page 2 ©2004 Pennsylvania Patient Safety Authority Reprinted from the PA-PSRS Patient Safety Advisory—Vol. 1, No.4 (December 2004) Venous Air Emboli and Automatic Contrast Media Injectors (Continued) Table 1 Symptoms that May Indicate Venous Air Embolism During Power Contrast Injection Cardiopulmonary Neurological Gasp Focal paralysis Cough Seizures Acute shortness of breath Loss of consciousness Tachypnea Altered mental status Chest pain/unilateral chest pain Coma Chest pressure Loss of sensation in an extremity Pulmonary edema Vertigo Bronchospasm Blindness Crepitus Other Hypercapnea or hypocapnea Sense of impending death Cyanosis Nausea and vomiting Hypoxemia Hypotension Sources Hypercarbia Pham KL, Cohen AJ. Iatrogenic venous air embolism during contrast enhanced Increased central venous or pulmonary artery pressure computed tomography: a report of two cases. Emergency Radiology 2003; 10:147- 51. Sinus tachycardia/sinus bradycardia Ie SR, Rozans MH, Szerlip HM. Air embolism after intravenous injection of contrast Ischemic changes on EKG material. Southern Medical Journal 1999 Sep;92(9):930-3. Nonspecific ST segment and T wave changes Aurora R, Ward KR, Garza R, Rivers E. Iatrogenic venous air embolism. The Cardiac conduction disturbance Journal of Emergency Medicine 2000 Feb;18(2):255-6. Extreme venous congestion Temple AP, Katz J. Air embolism: a potentially lethal surgical complication. AORN Acute cor pulmonale Journal 1987 Feb;45(2):387-400. “Mill-wheel” murmer – if large air embolus in right ventricle Orebaugh SL. Venous air embolism: clinical and experimental considerations. Critical Care Medicine 1992 Aug;20(8):1169-77. Competency • Inspecting the cannula and the connection be- • Periodically verifying radiologists’ and technolo- tween the cannula and power injector system to gists’ performance compared to current proto- verify that no air is introduced into the system, cols.1 both prior to initial injection and between multiple injections of contrast.1,3,13 Written Procedures/Instructions • Having contrast injector procedures readily • Aborting the procedure if air is noticed in the con- available to the healthcare workers.10,11 trast injection system/tubing or when contrast is not seen coming out of the catheter.3,10,11 • Reviewing procedures and operator’s instruc- tions before using any invasive diagnostic equip- Protocols ment.3,10,11 Developing protocols, conducting drills, and promot- ing compliance to clarify: • Following the manufacturer’s instructions and operating manuals concerning all aspects of • How contrast injection responsibilities will be han- contrast injection, including the prescribed load- dled and transitioned during work shift changes. ing sequence before arming the injector or pre- paring the contrast for injection.12 • How specific tasks will be accomplished, accord- ing to the type and number of staff involved.1 For • Using a double check system to help ensure example, while a radiologist is involved in con- that the syringe is removed from its jacket and trast-enhanced imaging, it is possible that one or filled with contrast media, the system is purged two technologists may also be involved. Defining of air, and the syringe is loaded—all before at- tasks for each healthcare worker in these differ- taching the injector syringe and tubing to the IV ent situations may help to prevent duplication or cannula.10,11,13 performance gaps. • Verifying that empty syringes are not left in injec- tors at the end of the procedure.3 ©2004 Pennsylvania Patient Safety Authority Page 3 Reprinted from the PA-PSRS Patient Safety Advisory—Vol. 1, No. 4 (December 2004) Venous Air Emboli and Automatic Contrast Media Injectors (Continued) Equipment • Air detection devices may reduce the risk of air embolism associated with contrast media injec- tors, but only if used in conjunction with other risk reduction measures designed to address user error. • Using tightly sealed, locking connections to the venous line may reduce the risk of air entry from a source outside of the contrast media injector. Reporting • Notifying the person at your facility responsible for reporting air emboli associated with contrast injec- tors. Notes 1. Pham KL, Cohen AJ. Iatrogenic venous air embolism during con- trast enhanced computed tomography: a report of two cases. Emerg Radiol 2003;10:147-51. 2. Ie SR, Rozans MH, Szerlip HM. Air embolism after intravenous injection of contrast material. South Med J 1999 Sep;92(9):930-3. 3. Gallauresi BA. Safeguarding contrast media injections. Nursing 2001 Jan;31(1):24. 4. Orebaugh SL. Venous air embolism: clinical and experimental considerations. Crit Care Med 1992 Aug;20(8):1169-77. 5. Petts JS, Presson Jr. RG. A review of the pathophysiology of ve- nous air embolism. Anesthesiol Rev 1991 Sep/Oct:18(5):29-37. 6. Lambert MJ. Air embolism in central venous catheterization. South Med J 1982 Oct;75(10):1189-91. 7. Groell R, Schaffler GJ, Reinmueller R, Kern R. Vascular air embo- lism: location, frequency, and cause on electron-beam CT studies of the chest. Radiol 1997 Feb;202:459-62. 8. Temple AP, Katz J. Air embolism: a potentially lethal surgical com- plication. AORN J 1987 Feb;45(2):387-400. 9. Aurora T, Ward KR, Garza R, Rivers E. Iatrogenic venous air em- bolism. J Emerg Med 2000 Feb;18(2):255-6. 10. Health Devices Alerts Accession Number 30082 [database online]. Plymouth Meeting (PA): ECRI; 1997 Jan 17. 11. Health Devices Alerts Accession Number 38144 [database online]. Plymouth Meeting (PA): ECRI; 2001 Mar 16. 12. Medical Device Reporting (MDR) Database Access Number M102517 [database online] Washington (DC): FDA Center for De- vices and Radiological Health; 1985 Mar 11. [cited 2004 Sep 17]. Available from Internet: http://www.accessdata.fda.gov/ scripts/cdrh/cfdocs/cfmdr/Detail.CFM?ID=617011 13. ECRI. Healthcare Product Comparison System. Technology overview: injectors, contrast media; angiography; computed tomogra- phy; magnetic resonance imaging. 2002 Oct. Page 4 ©2004 Pennsylvania Patient Safety Authority Reprinted from the PA-PSRS Patient Safety Advisory—Vol. 1, No.4 (December 2004) An Independent Agency of the Commonwealth of Pennsylvania The Patient Safety Authority is an independent state agency created by Act 13 of 2002, the Medical Care Availability and Reduction of Error (“Mcare”) Act. Consistent with Act 13, ECRI, as contractor for the PA-PSRS program, is issuing this newsletter to advise medical facilities of immediate changes that can be instituted to reduce serious events and incidents. For more information about the PA- PSRS program or the Patient Safety Authority, see the Authority’s website at www.psa.state.pa.us. ECRI is an independent, nonprofit health services research agency dedicated to improving the safety, efficacy and cost-effectiveness of healthcare. ECRI’s focus is healthcare technology, healthcare risk and quality management and healthcare environmental management. ECRI provides information services and technical assistance to more than 5,000 hospitals, healthcare organizations, ministries of health, government and planning agencies, and other organizations worldwide. The Institute for Safe Medication Practices (ISMP) is an independent, nonprofit organization dedicated solely to medication error prevention and safe medication use. ISMP provides recommendations for the safe use of medications to the healthcare community including healthcare professionals, government agencies, accrediting organizations, and consumers. ISMP's efforts are built on a non-punitive approach and systems-based solutions. ©2004 Pennsylvania Patient Safety Authority Page 5