©ECRI TRAINING SEMINAR ON MEDICAL DEVICE ACCIDENT INVESTIGATION for Kingdom of Saudi Arabia Saudi Food & Drug Authority Riyadh February, 2007 Presenter: Mark E. Bruley Vice President, Accident and Forensic Investigation ECRI 5200 Butler Pike, Plymouth Meeting, PA, USA Tel: , ext Web Sites: XVI. Gas Embolism Accidents with Medical Devices

©ECRI Gas Embolism Accidents Typical Devices and Causes Pneumatics/Hydraulics Models Patient Position Case Reports Investigating Pulmonary angiography shows an acute embolus (arrow) partially obstructing the right pulmonary artery. (From Gloviczki P, Yao, JST, eds. Handbook of Venous Disorders, 2nd ed. London: Arnold, 2001:218, Fig. 22.1a.) 2

©ECRI Heart-Lung Bypass Units Haemodialysis Units Blood Recovery Systems (Cell Savers) Gas-Cooled Laser Fibers Insufflators –Laparoscopic –Hysteroscopic –Ophthalmic –Arthroscopic Central Venous Cath. Ruptured Balloons: –Intra-Aortic Pumping? –PTCA Balloons Nitrogen Powered Surgical Instruments Infusion Devices Radiographic Dye Injectors Typical Devices: Gas Emboli 3

©ECRI Heart-Lung Bypass Accidents: Involved Devices Reusable –Bypass Pump Consoles –Gas Blenders –O2 Saturation Mon. –Anesth. Vaporizers –Gas Regulators –Gas Flowmeters –Bubble Detectors Disposable –Tubing Circuits –Oxygenators –Arterial Blood Filters –Cardiotomy Reservoirs

©ECRI Air Embolism Causes >50 possible causes Forced through IV tubing Forced onto open vein bed from end of surgical instrument Forced into uterine lining laser fiber cooling gas Forced into joint capsule from irrigating arthroscopic instrument Barotrauma of mechanical ventilation Luer Misconnections Passive entry into open jugular stopcock or diploic vein (skull) 5 See Health Devices handouts. See also: Sowell MW, Lovelady CL, et al. Infant Death Due to Air Embolism from Peripheral Venous Infusion. J Forensic Sci 2007 Jan 52(1):

©ECRI Pneumatic/Hydraulic Models Pressure differentials Flow rates Variation with time Height of patient related to blood or fluid filled lines. 6

©ECRI Patient Position Variation of blood flow and pressure Location of embolus entry points Location of organs

©ECRI Fatal Gas Embolism caused by intra-abdominal over-pressurization during laparoscopic cholecystectomy using argon enhanced coagulation (AEC) Patient’s intra-abdominal pressure increased above insufflator’s alarm limit (33 mmHg) Patient experienced difficulties consistent with gas embolism – confirmed at autopsy 8 Case Report: Argon Beam Coagulator Air Embolism

©ECRI It is possible for argon gas to enter open blood vessels AEC systems act as secondary source of pressurized gas causing intra-abdominal pressure to rise, exceeding venous pressure Argon is less soluble – not readily absorbed - in blood than CO 2 normally used for insufflation 9 Case Report: Argon Beam Coagulator Air Embolism

©ECRI Argon Beam Recommendations Limit argon flow to lowest levels possible Keep tip several millimeters from surgical site Flush cavity with CO 2 after AEC activations Leave one instrument cannula vent open Use patient monitoring (e.g., end-tidal CO 2 ) for early detection of venous or pulmonary gas embolism Make sure that staff is properly trained to detect and manage gas embolism 10

©ECRI Case Report: Aphaeresis Unit Air Embolism Fatal air embolism during blood aphaeresis (blood filtration) Death within 2 minutes of re-starting treatment Autopsy: >500cc air in heart and lung vessels Air seen in blood tube flowing from machine to patient. Two years of testing by vendor and authorities Case unexplained. Unit performance OK. Air detectors OK

©ECRI ECRI analysis, testing, and incident re- creation: –Air came from central line catheter in neck –Accumulated in superior vena cava –Air flowed in blood tube toward machine during troubleshooting –Blood tubing pulled out of one air detector –Air returned to patient when machine re- started –Open stopcock on neck catheter was cause –Air detector design contributory (tube dislodgement not detected) Case Report: Aphaeresis Unit Air Embolism

©ECRI Investigating Air Embolism Passive v. forced gas flow Device misconnections (e.g., Luer fittings) Biological routes v. machine routes Post Mortem Studies 13

©ECRI QUESTIONS? XVI. Gas Embolism Accidents with Medical Devices