Arterial cannulation is a common invasive procedure performed by anesthetists both within operating rooms and in the critical care unit. The ability to perform continuous blood pressure monitoring and repeatedly sample arterial blood has transformed the care of high-risk patients. The radial artery remains the commonest site of cannulation due to several advantages, including superficial location, consistent anatomic relations, and presence of an ulnar collateral circulation in most patients. Fortunately, since the introduction of arterial cannulation in the late 1940s, the incidence of serious complications has remained low, although a number of complications have been described in case reports.1–3 In this report, we describe the rare complication of arterial cannula transection followed by embolization of the distal fragment within the radial artery. We also discuss the use of ultrasound to identify the retained arterial catheter fragment enabling swift surgical removal.
The patient involved in this case report gave full written consent for the publication of this manuscript.
A 67-year-old woman underwent an emergency laparotomy for intestinal obstruction. Anesthetic management included insertion of a 16G peripheral venous cannula into the radial border of the right wrist, followed by a rapid sequence induction. After induction, a 20G arterial cannula with Floswitch (Becton Dickinson UK LTD, Wokingham, United Kingdom) was inserted into the right radial artery. Adequacy of ulnar collateral flow was confirmed using a modified Allen test before arterial cannulation. A central venous catheter was inserted into the right internal jugular vein using ultrasound guidance. Insertion of both lines was straightforward with no immediate complications. 3M Tegaderm IV dressings (3M United Kingdom PLC, Bracknell, United Kingdom) were placed over the 16G peripheral cannula and arterial cannula. The dressings were overlapped due to the proximity of the peripheral cannula and arterial line. A thoracic epidural was also inserted for intraoperative and postoperative analgesia. Surgery was uneventful, and the patient was extubated postoperatively. After this, the patient was transferred to recovery, while awaiting a bed on the critical care unit.
Because of some minor bleeding under the arterial line dressing, the recovery nurse decided to place a new dressing over the arterial cannula. The venous cannula and arterial cannula dressings were stuck together. To avoid disturbing the venous cannula dressing, the recovery nurse used scissors to cut away the arterial cannula dressing. During this process, the arterial line was completely transected just distal to the Floswitch. The distal fragment remained within the patient. Figure 1 demonstrates the remaining damaged hub of the arterial cannula. The distal fragment was not palpable under the skin surface and appeared to have displaced fully into the radial artery lumen. A peripheral vascular examination was performed at this point. The patient’s distal arm and the hand remained warm, pink, and well perfused with a normal capillary refill time.
In attempt to locate the distal fragment, plain films were taken of the patient’s right arm from wrist to shoulder. It was not possible to visualize the cannula fragment on plain films. Bedside ultrasound examination of the forearm vasculature was then performed. This revealed that the distal fragment was present in the proximal radial artery midway between the wrist and elbow. This is demonstrated in Figure 2.
The problem was discussed with a vascular surgeon, and the patient was immediately transferred for surgical retrieval of the fragment. Her arm was rescanned and marked by the vascular surgeon before incision under local anesthesia. On opening the radial artery, the fragment was not present. When the arm was rescanned, the fragment was found to have migrated toward the brachial artery. The incision was extended along the radial artery, and the fragment was successfully retrieved. The radial artery was extensively thrombosed along the segment incised and the vascular surgeon was of the opinion the artery was not amenable to repair. In view of this and the presence of good ulnar collateral flow, the radial artery was ligated and excised. Fortunately, due to the presence of an ulnar collateral supply, the patient suffered no long-term vascular compromise to the upper limb.
The patient received a full explanation of events and this was recorded and investigated as a critical incident.
Iatrogenic cannula damage and loss of the distal fragment into the artery remain rare complications of arterial cannula insertion. It is important to review the causes in each case to ascertain what lessons can be learned. Shah et al4 reported damage to an arterial cannula while securing it to the patient with sutures. Ferguson et al5 described accidental transection when attempting to remove the arterial cannula sutures with a stitch cutter. Interestingly, 3 case reports describe accidental transection of the arterial cannula with scissors during dressing removal,6–8 mirroring the exact sequence of events in this case report. In 2 case reports, the cause of cannula damage was unclear.9,10 The recurring theme is cannula damage resulting from the use of sharp implements to remove cannula dressings and/or sutures. To reduce the risk of cannula damage, we would advise vigilance when securing the arterial cannula with sutures and that great care is taken when using scissors to remove line dressings. After this case, as a department, we introduced new guidelines adapting these measures and provided additional training for recovery staff.
It is worth discussing the imaging methods best suited to locating the lost intraarterial cannula fragment. In first instance, it may be possible to locate the fragment using plain radiographs. This technique was successful for Imran Hamid et al.6 However, in our case, the fragment was not visible in both anteroposterior and lateral views. Mayne and Kharwar10 were also unable to obtain clear visualization of the retained cannula fragment using plain films. Luo et al8 attempted to use the C-Arm (Siemens Healthcare Limited, Frimley, Camberley, Surrey, United Kingdom) in theater to image the fragment, but this also proved ineffective due to poor image quality. As an alternative, a computed tomography scan of the arm was performed with 3D reconstruction. This enabled excellent visualization of the retained fragment. However, because this exposed the patient to a significant dose of ionizing radiation, we would not recommend this as an initial imaging strategy.
In our case, we utilized bedside ultrasound to successfully identify the retained fragment. Moody et al7 also reported the successful use of ultrasound in a similar clinical situation. Using the high-frequency linear probe of a Sonosite S-Nerve ultrasound machine (FujiFilm SonoSite European Headquarters, FujiFilm SonoSite BV, Amsterdam, the Netherlands), we could rapidly acquire high-quality images of the intraarterial fragment and mark its location on the patient’s arm. We would recommend ultrasound as the primary mode of imaging in this clinical scenario because it is noninvasive, reliably images the intraarterial foreign body, and can be performed rapidly at the patient’s bedside. It can also be used during removal to guide the surgical incision site and reduce the incision size along the artery.
Another point of discussion relates to the behavior of the intraarterial foreign body. The fragment would be expected to move distally with forward flow and impact in the superficial palmer arch. Interestingly, the fragment began to move proximally, rather than distally, toward the brachial artery. This may have been due to collateral flow entering the radial artery between the embolized catheter and the artery at the wrist.
In conclusion, iatrogenic arterial cannula transection is a rare yet potentially serious complication of insertion. By exercising vigilance when securing the arterial cannula with sutures and taking great care when using scissors to remove dressings, the risk of this complication may be reduced significantly. In the event of this complication occurring, we would advocate the use of bedside ultrasound as the imaging modality of choice to identify the intraarterial fragment. In the cases reviewed, plain films did not appear to represent a reliable imaging modality to identify intraarterial cannula fragments. We would also like to highlight the importance of repeating the ultrasound scan of the artery once it has been surgically exposed in theater. This is crucial as the fragment may have moved after surgical manipulation of the limb. By reconfirming the fragment position, the arterial incision length can be minimized. Finally, and most importantly, the affected patient requires prompt referral to a vascular surgeon or interventional radiologist.
Name: Andrew C. Leatherbarrow, MBChB, MRCP, FRCA.
Contribution: This author helped acquire images used in the manuscript, acquire written consent from the patient to publish the case report, and prepare and edit the manuscript.
Name: Alina Bucata, MD.
Contribution: This author helped search the literature, and prepare and edit the manuscript.
This manuscript was handled by: Raymond C. Roy, MD.
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