Lint and Particle Contamination During Diagnostic and Interventional Procedures in the Cardiac Catheterization Lab
The purpose of cardiac catheterization has advanced significantly over the decades from one of supportive diagnostics, to one more of treatment. Rashkind was the first to report a successful corrective procedure when he described the use of catheterization for atrial septostomy with complete transposition of the great arteries in 1966.1,2 Since then, cardiac catheterization has replaced many conventional therapeutic and palliative procedures, reducing cost and post-operative complications while improving quality of life for literally millions of patients. Although complications are comparatively far fewer, interventional cardiac catheterization has its own set of complications that may include arterial or venous thrombosis, disseminated intravascular coagulation (DIC), foreign body embolization, phlebitis, endotoxemia, cardiac dysrhythmias, infection and restenosis. 1,3 These complications can be caused by the catheter itself, the balloon (or fragments thereof), any device being implanted such as a coil or stent, or, of course, poor technique. Complications may also be caused or exacerbated by foreign debris deposited on the inside or outside surfaces of the catheter and subsequently co-inserted into the bloodstream. Because of the direct vascular insertion and extensive surface area exposed, minimally invasive procedures conducted through the circulatory system may actually place the patient at greater risk of particulate-related complications. Investigators have demonstrated that contamination with lint, powder and other particulates may occur during procedural preparation or actual surgery. However, rarely are embolic clots, inflamed vascular walls or overgrown neointimal areas examined histologically to investigate the possible presence of microscopic condensation nuclei. Where histopathologic investigations have been performed, the results have been very illuminating and provide evidence-based precautionary recommendations for avoiding foreign debris-associated complications during cardiac catheterization as well as any other form of vascular catheterization.
Studies and Reports
Whelan performed a stent evaluation study in which he implanted a total of 147 stents into 111 pigs under full operating room environmental conditions. The animals were studied up to 12 weeks post-implantation. Of the 46 animals that were randomly sampled, twelve experienced stent thrombosis. Histological examination of thin layered clot sections under polarized light, followed by Periodic Acid Schiff (PAS) staining, revealed glove powder and lint at the center of 42% and 12% of the clots, respectively. Without histological study, there would have been no thought as to the possibility of particulate contamination as a causative agent.4 Whelan also examined the cardiac tissues where he identified particles covered with inflammatory cells in capillaries of the myocardium. He discussed how thrombi continue to enlarge as more inflammatory cells are recruited, snow-balling into ever more threatening size. Eventually the enlarged clots could block critical cardiac vessels or find their way into the pulmonary or cerebral circulation. Pulmonary emboli or cerebral stroke could ensue. Whelan emphasized that these findings may help to explain that while most subacute thromboses occur three to five days post-implant, they have been reported up to 28 days post-implant as the swelling thrombogenic mass reaches critical size. 4 Histological preparation of stented vessels revealed lint fibers in the neointima (new vascular lining) covered with adherent cells, proteins, and platelets. The investigator noted that the endothelial cell multiplication necessary to cover the lint imbedded in the vascular lining caused sufficient hyperplasia to potentially result in restenosis. Tissue sections also revealed giant cells surrounding these particles in the neointima, potentially indicating the initial stages of granuloma formation in the stented coronary artery. It has also been noted in both studies and reported clinical outcomes that lint has caused acute and persistent inflammation, poor quality scar formation, granulomas, adhesions and reduced resistance to infection. Tinker verified that cellulose fibers from the surgical drapes used in the operating room were the pathological agents in 45 cases of granulomatous disease after the operating room switched to high linting cellulose-based drapes. 5 A recently published study by Shannon reports a five-year retrospective study of all postmortem cases of post-angiographic neurologic complications at Toronto Western Hospital. Histologic examination was performed on all surgically resected central nervous system arteriovenous malformations. He found particulate embolization present in as many as 25% of the malformations studied. Three patients with cerebral infarction, sometimes catastrophic, were directly attributable to particulates introduced during cerebral angiography. Shannon concluded that unintentional foreign body emboli remain common in modern angiographic practice and are probably underappreciated clinically. Although such emboli are usually asymptomatic, they can be clinically devastating, and a high index of suspicion is required for diagnosis. Foreign body emboli should be included in differential diagnosis of post-angiographic ischemia or infarction. 6 Chapot, in his recent publication, Occlusion of the middle cerebral artery due to synthetic fibers in the American Journal of Neuroradiology, describes failed attempts to retrieve a significant thromboembolism inadvertently created during catheterization to treat a cerebral aneurism. Retrieval was finally successful using mechanical thrombectomy with a microsnare. Pathologic analysis of the thrombus revealed numerous synthetic fibers as the causative agents. 7 McKee identified particulate matter introduced during catheterization as the cause of granulomas of the endocardium. In one case, a 36-year-old male who presented dyspnea on exertion was in atrial fibrillation with a mitral systolic murmur. Rheumatic heart disease was confirmed during cardiac catheterization with moderate to severe mitral stenosis and aortic regurgitation.During mitral valve replacement, a 1 cm specimen presumed to be a blood clot was sent to pathology. Histologically, the mass was composed of sheets of macrophage-type cells enmeshed in a fibrin web, engorged with trapped red blood cells, all engulfing particulate matter throughout the clot. 8 In another case, a 52-year-old male was admitted with left ventricular failure. He was diagnosed with Q fever endocarditis. Antibiotic treatment was initiated. Catheterization confirmed severe aortic incompetence. Nine days later, his mitral valve was replaced. During surgery, a large thrombic mass attached to the aortic valve was noted. Histopathological examination revealed an abundant clot (fibrin, platelets, red blood cells) in which was enmeshed sheets of macrophages associated with numerous particles introduced during cardiac catheterization. 9 Bookstein identified lint contamination as one of the precipitants of hypercoagulant conditions associated with angiography. 10 Nine days after mitral valve surgery, a 44-year-old patient died when a mural thrombus enlarged sufficiently to block blood flow into the aorta. Histopathology revealed the inflammatory cells, fibrin, platelets, and red blood cells had amassed around particles deposited into the bloodstream. 11 Cina described the formation of a lethal blood clot initiated by a tiny suture trim fragment. The thrombus formed rapidly and lodged in the left anterior descending coronary artery. The patient died while still in surgery. The larger the particle contaminating the bloodstream, the more rapidly the thrombus forms and, generally, the more severe the consequences. 12
In each of the described cases, the body’s attempts to devour, destroy or blockade the lint fibers, powder and other particulates perceived as threats, actually become the greater dangers. This walling off can produce a thrombi or lesion on the inner surface of a blood vessel, heart, brain, kidney, lung or anywhere else in the body. These formations may be of no consequence, produce a range of complications or become catastrophic.
A very brief listing of the size of the contaminating particle and the most probable location of vascular blockage are noted in Table 1 as a summary of pathological studies. 13 Particles in the 4-micron range are generally phagocytized and carried away in the lymph system. However, if they avoid capture and become the nucleus of a clot, they can finally lodge in terminal blood vessels. The severity of the lesion depends on the location of the clot (or granuloma-clot hybrid), the breadth of ischemic injury and the presence or absence of collateral circulation. 14 Particles in the 10 micron range would include powder and smaller lint fibers. The mechanism of cellular encasement is the same but the enlargement tends to happen more rapidly. Particles in the > 40 micron range include lint fibers, powder aggregates, suture trims and aggregate contrast media crystals. The sites of possible blockage are the lung and the heart. Because clots from large particles form rapidly, they will often become trapped within the vessels of organs near the site of particle introduction into the circulatory system although a large percentage do end up in the lung or heart. Patients who recover from thrombic infarctions may have no residual effects, local area lesions with local effects, or more chronic sequela such as multiple organ dysfunctions (MODs), acute respiratory distress syndrome (ARDS), cerebral stroke, and latent valvular or other infections.
Lint or other particles forced into vascular endothelium If the fiber is forced into the vascular endothelium by the pressure of an inflated balloon or expanding stent, the body may respond in several ways. The endothelium may merely expand to cover the protrusion, making the vessel diameter a bit narrower. Alternatively, the presence of the particle sticking out into the vascular lumen may be sufficiently provocative that hyperplastic efforts to totally cover the foreign body with endothelial cells may create sufficient thickness to cause reactive restenosis. Or, the inflammatory response may be activated in an attempt to destroy the foreign debris such that neutrophilic oxygen radicals, complement cascade components, platelet aggregates, and fibrin are deposited over the protruding foreign debris. The local inflammatory response injures the endothelium surrounding the fiber. This collateral tissue damage triggers the release of cytokines and chemotactic factors, heralding an escalated inflammatory response. The ensuing injury of the endothelium forms a localized phlebitis, which itself can trigger clot formation or restenosis.
Reduced resistance to infection Foreign debris, clots and phlebitis all lower an individual’s resistance to infection. The immune response becomes preoccupied in ridding the body of the obvious threats, losing focus on the few bacteria seeding the bloodstream. Elek demonstrated that the number of bacteria required to initiate an infection in wounds drops from 105 or 102 when distracting foreign debris is present. 15 Jaffray confirmed the same marked reduction in immune protection, reporting an increase in infections from 10% in group A to 90% in group B when both animal groups received the same 103 inoculum of Staphylococcus aureus, but group B co-introduced 2 mg of sterile particles (7-30 microns on average). 16 This reduced resistance to infection in the presence of foreign debris was also described by Zimmerli. 17
Mechanisms by Which Devices Can be Contaminated
Handling In his study, Whelan determined that he had contaminated the bloodstream with lint and glove powder while handling the catheters, balloons, guidewires or stents just prior to and during insertion of his extradural catheters. Handling devices with powdered gloves, gauze or drapes during preparation, while inserting the guidewire and cannula, or when manipulating devices on high linting drapes can result in foreign debris contamination. 18 For instance, instructions for the preparation and insertion of St. Jude Medical Left Ventricular Leads (LV), warn against contamination of the device by lint and other particles which would be co-inserted with the device and could lead to complications. 19
Electrostatic attraction Stein found that particles were drawn to plastic sheaths by electrostatic attraction and co-inserted with intraocular lenses during ophthalmic surgery. As most catheters are plastic, similar debris attraction and capture would be anticipated by vascular catheters used routinely in cardiac cath labs and in interventional radiology labs. 20
Placement After experiencing an increased incidence of fever, infection and inflammation during and after anesthesia administration, Greene observed significant particulate contamination of his catheters (scanning electron microscope). He had assumed that the catheters were contaminated by the manufacturer until examination immediately after removing from the sterile packaging failed to detect any surface debris. After handling the devices and setting them down on sterile surgical drapes prior to insertion, he was able to determine that the particle contamination occurred at the pre-insertion and insertion stages. 21
Lint Lint contamination may occur from drapes, gowns, gauze, sterilization wrap, warming blankets, towels, cleaning rags, clothes worn by observers and other sources.
Drapes Drapes for use in diagnostics and interventional procedures performed in the the cath lab and interventional radiology lab are usually extra absorbent to manage the heavy exposure to fluids. Absorbency can be incorporated utilizing a number of different fabrics and treatments. Currently most of the super-absorbent drapes incorporate cellulose or cellulose/polyester (woodpulp/polyester) for absorbency. This is backed with a plastic film laminate to prevent fluid strikethrough to the patient. This results in direct contact of the devices with the short, easily frayed cellulose fibers. When guidewires, catheters, stents or other instruments are placed on and then dragged across the sterile surface, the lint is drawn to the surface by static cling. The more the device is manipulated and repositioned during preparation and insertion, the more static charge is built up on its surface, increasing particulate attraction. Manipulation of the device continues to break apart the entangled fibers, increasing the amount of available lint. Fabric made of SMS or hydroentangled long staple rayon/polyester fiber produce minimal lint. Lint from gowns, towels, cleaning rags, clothes, and sterilization wrap that could be aerosolized into air currents can also be attracted to the devices.
Gauze Gauze is a heavy contributor of lint contamination and yet is often used to wipe down the guide wire and even the stent. More than a static attraction, lint is usually snagged by the rough surface of the stent.
Reprocessed devices If intravascular catheters or other procedure components are re-used, they may be dried by, or laid upon, lint producing cloths contaminating the catheters. Particles may include not only lint, but also powder, crystalline granules in medications, dust, hair and particles from poorly cleaned devices which may include dried blood, tissue or bone fragments. Even though reprocessing may render the device (and particles) sterile, all the adverse sequelae previously ascribed to foreign debris deposits in circulatory system still applied.
Powder Needless to say, gloves are in continual contact with the catheter. If the gloves are powdered, the powder granules are readily deposited on the catheter surface and co-inserted into the bloodstream. Both cornstarch powder and calcium carbonate are on the exterior surface of the glove. Manufacturers may say that powder is not placed on the exterior surface, which is often true, but the drying step places all gloves in a huge dryer that mixes the powder and calcium carbonate to both the inside and outside. Both are readily transferred by static attraction. Green confirmed and documented the significant amount of powder that contaminated the surface of his extradural catheters by scanning electron microscopy. 21
Contaminants It is important to note that just as lint fibers may be coated with adhesives, dyes, fluid resistant treatments, etc., powder is coated with chemicals, accelerators (and other substances from the glove manufacturing process), proteins (if a natural rubber latex glove) and endotoxin (pyrogenic lipopolysaccharides). Drapes which utilize cellulose for absorbency mean one should be especially cautious of endotoxin contamination due to the heavy use of water-based steps in the manufacture of the raw materials, a harbinger of endotoxin contamination. Kure reported fever in 11.6% of his patients after cardiac catheterization. Investigations revealed that endotoxins were detected on the angiographic catheters only after they were handled with powdered gloves. He was able to reduce post-procedural fevers to 0.6% when glove powder was kept from the catheters. 22 Knudsen found endotoxins transferred from gloves to catheters during cardiac catheterization procedures. 23 Shmunes encountered post-surgical complications from endotoxins he believed to be related to his surgical gloves. He found many sterile surgical gloves to contain over the 20 EU/device limit required in the United States Pharmaocopeia (USP) for invasive devices, with one over 399 times the acceptable limit. There are no limits placed on gloves or drapes, although there is a recent voluntary test method (ASTM Designation: D 7102-04 Standard Guide for Determination of Endotoxin on Sterile Medical Gloves) for sterile gloves. 24,25
Air filtration Air filtration is another critical factor often overlooked in the areas where cardiovascular and cerebral vascular procedures are performed, even though filtration requirements have been established and been found to reduce airborne particulates. Compliant filtration set-ups are, however, of minor assistance in reducing particulates if doors are open, filters clog, or patient positioning defeats airflow pattern effectiveness. Healthcare guidelines addressing air filtration, number of exchanges per hour, the amount of fresh air required, etc. have been established by the American Institute of Architects (AIA) and are available on their website, www.aia.org. The Centers for Disease Control and Prevention (CDC) Guidelines for Environmental Infection Control in Health-Care Facilities (2003) utilize the AIA standards.
If patients develop clots or granulomas, a specimen should be submitted for histopathological analysis to determine the composition. This information can then be used to make changes in the surgical environment to reduce the incidence of particle contamination and its resulting complications.
Recommendations for Reducing Particulate Contamination
Select only low-linting drapes, gowns, headwear. Ask for the results of the Martindale Abrasion Test (ASTM D4966) and Gelbo Lint Generation Test (IST 160.1).
o The Martindale Abrasion Test is an industry standard to evaluate the resistance of a material to abrade (shear) and deteriorate as occurs during surgery at friction points (upper arm against side of chest, abdomen against table, drape surrounding fenestration where stents, guidewire and catheters are often dragged over and at times manipulated.) The results should be 3 or higher on a scale from 1 to 5.
o The Gelbo Lint test twists and expands and contracts a swatch of material (about 10 square inches) a specified number of times and analyzes the lint produced by pulling the surrounding air through a particle counter. The data produced provides the number of particles produced (background subtracted out) at specific size ranges. The results should be less than 20 particles measuring 10 microns or larger per 10 square inches of fabric for low-linting materials (and USP particle size limitations for devices through which fluids will enter the vascular system). Establish policies to ensure that linting fabrics are not used by housekeeping and that procedure rooms are kept thoroughly clean. Unfortunately, many hospitals do not take adequate precautions of cleanliness in interventional radiology and cath labs. Only powder-free gloves with low endotoxin levels (non-pyrogenic) should be worn by those preparing or inserting intravascular catheters in the OR, interventional or cath labs or when central lines are placed. Ventilation systems must be adequate and well-maintained. Doors should be closed. Personnel traffic should be kept to a minimum. Staff must wear gowns, caps and masks properly to ensure proper containment of hair, shedding skin, squamae and lint from personal apparel.
1. Remove a new catheter with guidewire from the manufacturer’s package.
2. Observe for particulate contamination under a high-power dissecting scope (pathology lab) or, if possible, under scanning electron microscope (SEM).
3. Prepare each of the components as your team normally would.
4. Simulate the manipulation, insertion and removal as in a normal procedure.
5. Examine the surfaces of the guidewire, catheter, and balloon with the same microscopic scrutiny. It may be necessary to dissect the absorbent area around the fenestration of drapes to see the color and microscopic appearance of the fibers when performing investigative analysis. Specifying the color may help to identify the offending particle contributor.
6. Measure the size of the fibers with an ocular micrometer.
7. Ask the manufacturer to identify the composition of the drape, including the absorbent area around the fenestration (often the highest-linting region). Avoid cellulose (woodpulp).
8. Rub a 6 piece of the absorbent area around the fenestration together ten times. Turn the material swatch one quarter turn and rub vigorously another ten times. Take a piece of crystal clear packing tape and place it on the rubbed area. Smooth the tape down with the side of the hand three times with firm pressure. Pull the tape off and repeat again after rotating the swatch one quarter turn. Now, place the tape onto something like a plastic disc holder (jewel case) with one clear side and one black side. With the tape on the clear side, the lint is clearly visible against the black. Label the manufacturer and proceed to the next test material.
Note: This same procedure is applicable to the evaluation of fabric fiber contamination of stents.
1. Place a pair of sterile, powdered gloves of the type normally worn by the surgeon, anesthetist or interventional radiologist performing the targeted procedures, into a glass of water (conical base is the best).
2. Agitate with a rod or other implement for 10 seconds.
3. Remove the gloves, pouring any water still in the gloves back into the glass.
4. Allow 30 minutes for the powder to settle. As glove powder cornstarch is cross-linked with epichlorohydrin or phosphorus oxychloride, the powder will not dissolve, but settle to the bottom within 30 minutes. This settling allows volume comparison among brands.
There is often a failure to recognize that particulate contamination can cause significant post-procedural complications when less invasive cardiovascular or cerebral vascular procedures are performed in cardiac cath labs or in interventional radiology labs. The cath labs, interventional labs and traditional operating rooms should be assessed for sources of lint contamination, poor device preparation, poor insertion practices, poor quality of air filtration, and non-compliance with attire and area traffic policies. Furthermore, the staff, physicians, housekeeping and central services should be educated as to the importance of preventing lint, powder and other particulates from contaminating catheters, guidewires, stents, coils, etc. Thus, it is important that staff 1) understand the consequences of inoculating lint, powder and other particulates into the bloodstream; 2) ensure practices do not increase the risk of particulate contamination; 3) select only low lint and low particulate generating drapes, gowns, gloves and other medical products.
Dr. Wava Truscott can be contacted at email@example.com
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