Although arterial cannulation is a generally safe procedure, complications can occur. The total complication rate is estimated to range from 15% to 40% of procedures, although clinically significant occurrences are limited to < 5%.1,2,3,4,7,9 Of these, some of the more common incidents include thrombosis and arterial occlusion, embolization and organ ischemia, infection, bleeding, and/or hematoma formation. Less severe but still common complications include vasospasm, diagnostic blood loss, and pain. Heparin-induced thrombocytopenia is also a problem as a result of the heparinized solution sometimes used in continuous flush systems.
Thrombosis is the most common complication associated with catheter placement.3,9 It is far more common in the narrow vessels of the distal circulation than in the larger central arteries. In addition to site selection, the incidence of thrombosis increases with duration of indwelling catheter use, length and gauge of arterial catheter selected, and predisposing hypercoagulable state.9 It is mitigated by use of a continuous flush system, which works to limit stagnation or turbulence of blood flow through the catheter. Although thrombosis may occur, it is usually not a serious complication in that it rarely results in clinically significant ischemia. Furthermore, ischemia usually resolves with catheter removal, and the thrombus is resorbed within several weeks of catheter removal. Clinically significant ischemia is rare, occurring in < 1% of arterial catheter placements, and usually develops in the setting of preexisting or concurrent circulatory alterations. However, when surgical intervention for ischemia is required, partial to total amputation of the affected extremity is frequently necessary.
Cerebral embolization occurs as a result of either air being externally introduced into the systemic circulation, or via dislodgment of a thrombus at the catheter site. It is frequently associated with peripheral cannulation at radial and brachial sites, although has the potential to occur with any catheter. Since gas travels up a fluid-filled system, air will travel up to the cerebral circulation in a sitting or nonrecumbent patient. The rate of instillation of air into the circulation will also predispose to higher rates of embolization. Manual flushing of the arterial catheter with a syringe as opposed to use of the flush valve can cause higher volumes of air to be introduced. Clinical relevance, if any, depends on the site of embolization, the volume of air involved, and the extent of vessel occlusion.
As with any percutaneous procedure, there is a risk of infection associated with arterial catheterization. The most common routes of arterial infection include contamination with skin flora during catheter insertion, contaminated sterile flush/infusate system, and introduction of bacteria during blood drawing or opening of the tubing–stopcock system to the ambient environment. Common practices to mitigate infection include the use of chlorhexidine solution prior to catheter insertion, use of sterile technique during insertion (including mask, sterile gown and gloves, and hair cap if necessary), and covering stopcocks with diaphragms instead of caps.1 Routine changing of the tubing/transducer system varies across institutions; 96 hours is a common practice. Routine changing of the arterial catheter itself is infrequently performed as arterial catheterization results in a very low rate of bacteremia (0%-5%),1 and is rarely the cause of fever. However, repeat cannulation at a new site may be indicated if all other sources of sepsis are ruled out. The most common bacterial isolate from arterial catheters sent for microbial analysis is Staphylococcus epidermidis. If bacteremia from the arterial catheter is confirmed, treatment with appropriate antimicrobial agents is indicated.
Hemodynamically Significant Retroperitoneal Bleeding
The femoral artery is a large vessel that is frequently selected in emergent situations due to ease of cannulation. However, improper technique can result in transection of the artery and resultant bleeding into the retroperitoneal space. Large amounts of occult bleeding into the retroperitoneum can occur. Unexplained hemodynamic instability and pallor after femoral arterial catheterization should be promptly evaluated radiographically if hematoma or bleeding is suspected.
Percutaneous puncture of smaller, superficial arteries may result in smaller, visible hematomas; these are more frequently seen at the radial, brachial, and dorsalis pedis sites, but can be seen with axillary puncture. If superficial hematoma develops, direct manual pressure should be held until the hematoma is reduced and the area is soft. The procedure should be aborted, and a new site selected.
Vasospasm may occur under similar conditions to local hematoma formation. The small, superficial radial, brachial, and dorsalis pedis arteries may become vasospastic after cannulated. If the catheter is unable to be placed due to obstruction or inability to advance the guidewire, the operator may notice diminution of a palpable pulse. In such circumstance, the procedure should be aborted and a new site selected, as further attempts at cannulation of the artery are less likely to be successful and may result in unnecessary patient discomfort.
Significant blood loss can occur from frequent arterial blood sampling as a result of the need to draw intraarterial blood that is not contaminated by saline diluent or heparinized flush from the transducer system. In order to assure that pure blood is taken, 3 to 5 ml of blood is extracted prior to obtaining the sample for analysis. This can aggregately lead to an increased need for transfusion (with associated morbidity risks). Mitigation of blood loss can be achieved through use of pediatric tubing (smaller volumes), utilization of tubing systems that incorporate a reservoir, and point of care rather than traditional chemical analysis.
Heparin-Induced Thrombocytopenia (HIT)
Some institutions use small amounts of heparin in the arterial flush solution. In critically ill patients with new thrombocytopenia (platelet count decrease of 50% of preheparin levels or absolute platelet count of < 100,000/ml) but no clear etiology, HIT should be considered. If heparin is considered to be a likely cause of thrombocytopenia, all use of heparin in the flush solution should be discontinued. Alternatives include sodium citrate, lactated Ringer’s, or 0.9% saline solution.