ARTERIAL CATHETER COMPLICATIONS AND MANAGEMENT PROBLEMS

ARTERIAL CATHETER COMPLICATIONS AND MANAGEMENT PROBLEMS Observations from AACN's Thunder Project AACN Thunder Project Task Force Arterial cannulation is a common procedure in the care and management of critically ill patients. Blood pressure measurement, arterial blood sampling, cardiac output determinations, and a site for rapid blood withdrawal are the primary reasons for arterial cannulation.14 As is true with any invasive catheter placement, arterial catheters impose certain risks and clinical management problems. The Thunder Project was undertaken by the American Association of Critical Care Nurses (AACN) to determine the effects of heparinized and nonheparinized flush solution on the patency of arterial lines for pressure monitoring. Data were received on 5037 patients in 198 hospital critical care units in the United States, Canada, and Australia. Manuscript prepared on behalf of AACN and all participating sites by members of the Thunder Project Task Force and national office staff: Carol Ledbetter, RN, PhD, CS, Chairperson; Thomas Ahrens, RN, DNS, CCRN; Pauline Beecroft, RN, PhD, Senior Research Specialist; Barbara Brown, RN, PhD, CCRN; Anna Gawlinski, RN, DNSc, CCRN; Leslie Kern, RN, MN, Research Specialist; Andrea Quinn, RN, MS, CCRN, CS; Karen Sechrist, RN, PhD, Director of Research; Cindy Strzelecki, RN, BSN, CCRN, Board Liaison; and Susan Walsh, RN, MSN, CCRN, CS. Thunder Project is a registered trademark of AACN. Findings from that study are reported elsewhere. l The data collection procedure involved checking the patency of the arterial lines by performing a square waveform test and determining arterial blood backflow every 4 hours for 72 hours after insertion of the line or until the line was removed. The presence or absence of an acceptable square waveform and arterial backflow were recorded on a data collection form. An acceptable square waveform test was defined as a rapid upstroke terminating in a flat line at the maximal indicator on the tracing paper, upon activation of the fast flush device, and a rapid and unimpeded downstroke approximating a 90-degree angle, with a negative deflection below the baseline and a return to the arterial waveform within 0.12 seconds (three small blocks on the tracing paper), upon release of the fast flush device. Free backflow of blood was defined as a flashback of blood in the tubing at the interface of the catheter and the pressure tubing within 1 second, when the stopcock was turned off to the transducer and opened to air. Space for comments was provided for each data collection point. Site coordinators were instructed via an educational videotape to record discontinuation of arterial line, clotting, or other issues related to arterial

line management. They were also requested to record any change in the type of flush solution used, such as a change from lactated Ringers to normal saline. These comments provided insight into the day-to-day issues associated with arterial catheters and the management problems faced by the critical care nurse. These comments are now analyzed within the context of available literature. RELATED LITERATURE Most of the literature pertains to complications of arterial cannulation. Speculation as to the source of these complications varies. Complications In 1967, Mortensen 16 reported complications from 3,193 arterial needle punctures, cannulations, and incisions. The overall complication rate was 13%, including 66 major and 321 minor complications. The most common major complication was thrombosis at the entry site with distal ischemia. More recent studies show similar complication rates related to thrombosis. 5,15,25 Arterial catheterization thrombosis is characterized by occlusion, stenosis, pallor, hematoma, skin discoloration, local pain, and hand parasthesia. 25 Several studies have investigated arterial cannula thrombosis and the variables related to catheter patency. These variables include catheter dynamics, catheter location, and issues related to the monitoring system. Catheter Dynamics Teflon and polyethylene are the two most common materials used in arterial catheters. Teflon is reported in several studies to be less thrombogenic than polyethylene, 2, 5, 6, 7,11, 15 although one study found it to be more thrombogenic than polyethylene. 20 Lambert et ales compared both catheters for biocompatibility. The two catheters were similar in thrombogenicity, but a greater incidence of infection was associated with the polyethylene catheter. Gardner et al 10 found that the smooth hydrophilic surface of the Teflon arterial catheter limited air bubble formation within the catheter. Catheter length has not been studied as a factor related to patency. One review article recommended a 3.2- to 5.1-cm catheter for radial and brachial artery cannulation and a 16-cm catheter for femoral artery cannulation. 14 Catheter gauge has been studied relative to thrombus formation. Downs et al 1 found a significantly lowered incidence of vascular occlusion with 20-gauge catheters versus 18-gauge catheters. These findings were supported by Bedford 2 who performed arteriography of the wrist and hand. This modality demonstrated that the occlusive lesions in both size catheters were caused by accumulation of thrombus while the cannula was in place. Bedford hypothesized that the greater surface area of the 18-gauge catheter (20% larger than that of 20-gauge catheters) may contribute to its susceptibility to thrombus formation. A shortcoming of both studies was the absence of information on catheter duration. Bedford and coworker Wollman 3 later found that the risk of vascular complications associated with the 20-gauge catheter increased markedly after 3 days. The duration of radial artery cannulation appears to be a factor contributing to arterial occlusion, although results are conflicting. Bedford and Wollman 3 found that 20-gauge cannulas lasting 1 to 3 days produced 11% arterial occlusion, whereas those lasting 4 to 10 days induced a 29% incidence of occlusion. In a study to evaluate the effect of the location of the flush device on bacterial contamination, Shinozaki et a1 22 noted that, "no clinically important vascular complications occurred in any patient as a result of catheterization." Catheters were in place for as many as 439 hours for this study. Catheter Location Arterial catheters are most commonly placed in the radial and femoral arteries but also may be inserted in the brachial, axillary, and dorsalis pedis arteries. 6 The most common complication in radial artery placement is asymptomatic temporary radial artery occlusion, which resolves spontaneously. 2, 3 In a study of radial artery function in 108 patients, Bedford 2 found that the incidence of arterial occlusion increased linearly as the ratio of cannula outer diameter to vessel lumen diameter increased. Based on this finding, Bedford, 2 Purdue and Hunt1g recommend using the smallest possible cannula gauge. The literature on patency rates for femoral artery catheters is limited. Early research suggested a lower incidence of catheter loss due to occlusion in comparison with the incidence associated with radial artery catheters. 26 The incidence of loss subsequent to catheterization, however, may be as high as 1% to 4%. 14 Kaye 14 reviewed the literature on complications of femoral arterial cannulation and stated, "thrombosis of the femoral artery is especially common in the presence of peripheral vascular disease, following repeated attempts at insertion of catheters into the artery, and following prolonged, excessive pressure to control bleeding after catheter removal." Monitoring Systems In a classic article, Smith 23 described the equipment and arrangement for a pressure monitoring system.

Since this publication, changes have occurred in transducer technology, resulting in smaller, disposable transducers. Smith identified system problems and strategies for troubleshooting this system. Some of the problems identified included bleedback (due to loose connections, a partially deflated pressure bag, or incorrect stopcock position), air bubbles (due to loose connections, cracked system components, or flush device inadequacies), and a dampened waveform (due to clotted catheter or inadequate flush solution). A review of the more recent literature indicated that many of these initial system problems still occur. 4,12,13,17,19,24 Flush devices have been found to provide variable performance and to deliver higher flow rates than expected, 12,19 to malfunction, and to cause falsely high pressure readings. 21 In a case report, Passannante and Macik1 17 described a patient who was overheparinized due to repeated fast flushes of heparinized saline after blood withdrawal from hemodynamic lines. The amount of solution delivered by these fast flushes is variable and difficult to determine. Air entrapment in hemodynamic lines has been reported and attributed to turbulence created by fast flushing and other unidentified system problems. 4,10,24 Solutions to this problem include use of a macrodrip chamber for the flush solution and an in-line air filter. Pressure infusor bags have also come under scrutiny. Hart et a1 13 found that as the amount of solution under pressure decreased, the delivered pressures were less than the applied pressures. In addition, the difference increased as the volume of saline within the bag decreased. The reason for the difference between the inflation and delivered pressures is unclear. Because of these inaccuracies, pressurized systems cannot be counted on for accurate drug or fluid volume delivery, cuff inflation pressures must be maintained at 300 mm Hg at all times, and the flush solution bag should not be allowed to be depleted. Few studies have addressed the recognition and treatment of patency problems once they have occurred. Gardner et also studied catheter complications in 492 patients in an intensive care unit. Only five catheters become nonfunctional, three from clotting and two from kinking. Hypotension, use of vasoconstrictive agents, and prolonged catheterization were associated with complete arterial occlusion in the three patients requiring thrombectomy. Although most complications are related to the hematologic consequences of cannulation, infection is another category related to arterial cannulation. 8 The incidence of infection associated with arterial catheters used for pressure monitoring and blood sampling is reported to range from 1.6% to 11.5%. 9 Lines in place for longer than 4 days are associated with higher rates of infection. Studies of catheter insertion sites, however, do not consistently demonstrate an increased infection rate associated with insertion site. 9 OBSERVATIONS FROM THE THUNDER PROJECT Although the site coordinators and site research associates collecting data for the Thunder Project were given limited instruction for recording comments, many observations were included on the data collection sheet. These statements raise questions concerning the problems associated with the management of arterial lines, both with and without heparin in the flush solution. Problems fall into six general categories: (1) equipmentrelated problems, (2) patient-related issues, (3) patency problems, (4) subjective reports by the patient, (5) objective reports from the nurse, and (6) hematologic events. The following discussion provides a description of the problems encountered with arterial lines. The observations were random comments, and the actual numbers of problems are not reported. Accordingly, the extent of these problems, in practice, is unknown. Equipment-Related Problems Equipment-related comments focused on the arterial catheter, the flush solution bag, the pressure monitoring system, and the pressure infusor bag. A bent or kinked catheter was a common observation. Similarly, a break or leak in the pressure infusor bag, a leak in the flush solution bag, a crack in the monitoring system tubing, loose connections in the monitoring system, and defective pressure tubing were mentioned. These equipment problems may contribute to other problems, such as patency and hematologic events. For example, a broken pressure bag will not allow the flush device to function properly and to deliver the flush solution necessary to maintain patency. Patient-Related Problems Use of a positional catheter was a patient related problem. A positional line requires manipulation at the insertion site to provide an accurate waveform reading. Such an occurrence was determined to be a patientrelated issue, because an adequate waveform reading depends on patient positioning of the extremity in which the insertion site is located. Other issues that affected the integrity of the waveform readings included patient agitation, bradycardia, and shock.

Objective Reports Patency Several factors that appeared to precede the clotting or loss of patency of the arterial catheter were recorded and included a dampened or flat waveform, difficulty drawing blood from the line, and inability to aspirate blood from the line, sluggish or no backflow of blood from the arterial line, and difficulty flushing the arterial line. The exact sequence of these events and the time period before actual occlusion of the catheter require further analysis. Subjective Reports Patient complaints were recorded on the data collection sheet. They ranged from tingling, numbness, and pain to burning at the arterial catheter insertion site. The radial insertion site was the primary site of such complaints. Objective comments concerning the site of the arterial line revealed a variety of abnormal findings that may contribute to patient discomfort and morbidity. Comments included the following: (1) the site is red and inflamed; (2) the site is oozing and leaking; (3) the hand, wrist, and arm are edematous; and (4) the site is infiltrated and cool. At times, subjective reports correlated with objective data. For example, pain was associated with lower arm edema, and tingling and numbness with infiltration. Hematological Events Hematologic events included those related to either the extravasation of blood or the clotting of blood. Bleeding, hematoma, and bruising at the arterial catheter insertion site were mentioned, in addition to removal of a clot and a clotted or occluded catheter. DISCUSSION The link between the thrombotic complications and management problems associated with arterial cannulation is described in the literature as well as in comments provided on the Thunder Project data collection forms. Although the literature supports Teflon as the least thrombogenic material for the arterial catheter, other factors appear to be involved in thrombogenic risk. Results from the Thunder Project did not show rates of catheter patency to be significantly related to catheter material. Also, speculation that the 20-gauge catheter is better than an 18-gauge catheter because of its increased surface area is not supported by Thunder Project data. Arterial line patency was monitored for 72 hours; during this time, patency was not affected by catheter gauge. Although the literature provides support for the radial artery as a primary site for maintaining patency, Thunder Project data identified the femoral site as having a significantly increased chance for patency when compared with other sites. Evaluation of the troubleshooting guide presented by Smith in 197823 reveals no progress in addressing the management prob-

ARTERIAL CATHETER COMPLICATIONS AND MANAGEMENT PROBLEMS lems associated with arterial catheters, identified more than 14 years ago. Comments onbleedback due to loose connections, partially deflated pressure infusor bags, anddampened or flat waveforms due to a clottedcatheter or inadequate flush solution are testimony to the lack of technologic progress in arterial cannulation and indwelling arterial catheter maintenance for the purposes of blood pressure measurement and arterial blood sampling. The number and variety of comments indicate that a great deal of nursing time is spentmaintaining line patency. Until the technologic issues associated with maintaining an indwelling arterial catheter are resolved, management issues surrounding arterial catheters will continue to be time-consuming. Theseproblems put the patient at risk for thrombosis and related complications in additon to jeopardizing the quality of the data used totreat the patient. CONCLUSIONS If critical care nurses are to continue to measure blood pressure by direct measures and to use indwelling arterial lines to obtain arterial blood samples, low-maintenance systems must be researched and developed. This research should focus on the following criteria that are desirable in this type of system: (1) a pressure bag that remains inflated regardless of the volume of flush solution; (2) catheters that do not kink or bend when in the artery; (3) flush solution bags and monitoring systems that maintain their integrity and that do not crack, break, or leak during operation; and (4) comfortable ways of maintaining limb mobility. The patient who is agitated and uncomfortable may self-impose catheter problems. The extent to which current systems can tolerate movement needs to be determined. Systems designed to permit freedom of movement need to be developed. Furthermore, research is needed regarding optimal catheter gauge to ensure accurate hemodynamic measures and vessel access while minimizing thrombosis and damage to the blood vessel wall. Optima) catheter length and its relationship to arterial insertion site necessitate additional investigation. Management of arterial catheter problems and prevention of complications by the critical care nurse remain crucial in care of the critically ill patient. Management issues will continue until arterial lines are replaced by noninvasive methods of monitoring pressure and obtaining the data provided by arterial blood samples. References 1. American Association of Critical Care Nurses: Evaluation of the effects of heparinized and nonheparinized flush solution on the patiency of arterial pressure monitoring lines: The AACN Thunder Project. Am J Crit Care 2:3-15, 1993 2. Bedford RF: Radial artery function following percutaneous cannulation with 18 and 20 gauge catheters. Anesthesiology 47:37-39, 1977 3. Bedford RF, Wollman H: Complications of percutaneous radial artery cannulations: An objective prospective study in man. Anesthesiology 38:228, 1973 4. Chang C, Dughi J, Shitabata P, et al: Air embolism and the radial arterial line. Crit Care Med 16:141-143, 1988 5. Crossland SG, Neviaser RJ: Complications from ra dial artery catheterization. Hand 9:287-290, 1977 6. Daily EK, Tilkian AG: Arterial access. In Tilkian AG, Daily EK (eds): Cardiovascular Procedures: Diagnostic Techniques and Therapeutic Procedures. St. Louis, CV Mosby, 1986 7. Downs JB, Chapman RL, Hawkins IF: Prolonged radial artery catheterization. Arch Surg 108:671-673, 1974 8. Falk PS, Scuderi PE, Sherertz RJ, et al: Infected radial artery pseudoaneurysms occurring after percutaneous cannulation. Chest 101:490-495, 1992 9. Gabriel D, Heard SO: Infectious complications of indwelling arterial and venous catheters. Cuff Rev Resp Crit Care 10:91-95, 1988 10. Gardner RM, Bond EL, Clark JS: Safety and efficacy of continuous flush systems for arterial and pulmonary artery catheters. Ann Thora Surg 23:534-538, 1977 11. Gardner RM, Schwartz R, Wong HC, et al: Percutaneous indwelling radial artery catheters for monitoring cardiovascular function. N Engl J Med 290:12271231, 1974 12. Gibbs N, Hart G, Cameron PD, et al: A comparison of continuous flush devices. Anaesth Intens Care 13:184-187, 1985 13. Hart GK, Gibbs NM, Cameron PD, et al: Pressure infusors: Variability in delivered infusion pressure. Crit Care Med 12:983-985, 1984 14. Kaye W: Invasive monitoring techniques: Arterial cannulahon, bedside pulmonary artery catheterization, and arterial puncture. Heart Lung 12:395-426, 1983 15. Lambert D, Martin C, Perrin G, et al: Risk of thrombosis in prolonged catheterization of the radial artery: Comparison of 2 types of catheters. Ann Fr Anesth Reanim 9:408-411, 1990 16. Mortensen JD: Clinical sequelae from arterial needle puncture, cannulation, and incision. Circulation 35:1118-1123, 1967 17. Passannante A, Macik BG: Case report: The heparin flush syndrome. A cause of iatrogenic hemorrhage. Am J Med Sci 296:71-73, 1988

18. Purdue GF, Hunt JL: Placement and complications of monitoring catheters. Surg Clin North AM 71:723 731, 1991 19. Rithalia SVS, Tinker J: Continuous flush devices for vascular pressure monitoring. Intens Care Med 9:295-298, 1983 20. Roberts GM, Roberts EE, Davies RL, et al: Thrombo genicity of arterial catheters and guidewires. Br J Ra dio150:415-418, 1977 21. Schwartz AJ, Stoner BB, Jobes DR: A hazard of the Intrafol continuous flush system. Crit Care Med 5:115-116, 1977 22. Shinozaki T, Deane RS, Mazuzan JE, et al: Bacterial contamination of arterial lines. JAMA 249:223-225, 1983 23. Smith RN; Invasive pressure monitoring. Am J Nurs 78:1514-1521,1978 24. Soule DT, Powner DJ: Air entrapment in pressure monitoring lines. Crit Care Med 12:520-522, 1984 25. Weiss BM, Gattker RI: Complications during and following radial artery cannulation: A prospective study. Intens Care Med 12:424-428, 1986 26. Williams CD, Cunningham JN: Percutaneous cannulation of the femoral artery for monitoring. Surg Gynecol Obstet 141:773-774, 1975 Address reprint requests to Karen R. Sechrist, PhD, RN, Director of Research, AACN 101 Columbia Aliso Viejo, CA 92656