In Reply

We thank Drs. Bowdle and Sheu for their interest and thoughtful comments on our recent article,¹  which reported a low risk of complications from intraarterial brachial pressure monitoring during cardiac surgery.

Although use of ultrasound is increasing, we typically use direct palpation of the brachial arterial pulse for our first attempt at arterial catheter insertion. Ultrasound for vascular cannulation was not available during the early years of our study period, and our current practice reserves this technology for difficult arterial cannulation. It is possible, however, that increasing use of ultrasound may lower the rate of complications even further than our initial report.

We follow guidelines established by the Centers for Disease Control²  to prevent intravascular catheter-related infections. Our standard practice includes proper hand hygiene and aseptic technique, preparation of clean skin with a more than 0.5% chlorhexidine preparation with alcohol, use of sterile gloves and drape, and a sterile, transparent, semipermeable dressing to cover the catheter site. Appropriate sterile dressing regimens are continued postoperatively by the nursing staff. Nonetheless, our low incidence of infection was likely overestimated because we conservatively reported bloodstream infections as “possibly associated” with brachial arterial catheterization, although the more likely cause was an infection related to a coexisting central venous catheter.³ 

We appreciate the suggestion from Drs. Bowdle and Sheu that an adequate collateral circulation may explain the low rate of brachial artery complications leading to hand ischemia and that embolic phenomena may have impaired the collateral circulation causing ischemia of the upper limb. Certainly, evidence of a collateral arterial network around the elbow exists,⁴  but whether this network is sufficient to adequately perfuse the hand after complete brachial artery occlusion in all patients is uncertain. It is possible that an adequate collateral circulation may have allowed a brachial arterial injury to remain undetected in some patients. However, multiple reports document hand ischemia as a result of reduced brachial arterial flow with inadequate collateral circulation, including patients suffering from supracondylar fracture with brachial arterial injury⁵  and after creation of a brachial-cephalic/basilic fistula,^6,7  thus providing evidence that collateral circulation is not adequate in all patients. Later development of adequate collaterals in patients with arteriovenous fistulas explains why some patients tolerate brachial arterial ligation,^8,9  although similar conditions do not occur in most elective cardiac surgical patients.

Although injury to the arterial wall during cannulation may create conditions conducive to thrombus formation,¹⁰  acute occlusion of the brachial artery may occur as a result of thrombus or emboli. It is thus unclear whether the collateral circulation was compromised in patients with an ischemic upper limb due to multiple emboli or whether its anatomical distribution was insufficient. Nevertheless, our data document that a thrombectomy of an occluded brachial artery restored perfusion to the hand and that the collateral circulation was inadequate in 18 patients.¹