Effect of ultrasonography and fluoroscopic guidance on the incidence of complications of cannulation in extracorporeal cardiopulmonary resuscitation in out-of-hospital cardiac arrest: a retrospective observational study

Out-of-hospital cardiac arrest (OHCA) is a major global public health concern. In the United States and Europe, approximately 330,000 and 275,000 individuals, respectively, develop OHCA annually [1, 2]. Despite the development of cardiopulmonary resuscitation (CPR), OHCA prognosis remains poor, with a survival rate of approximately 10% [1, 3, 4].

Extracorporeal membrane oxygenation (ECMO) is a technique for providing both cardiac and respiratory support to patients with cardiac or respiratory failure. Several observational studies showed that ECMO-assisted cardiopulmonary resuscitation, called extracorporeal cardiopulmonary resuscitation (ECPR), improved prognosis in special circumstances of OHCA [5‐10]. The American Heart Association (AHA) and European Resuscitation Council (ERC) guidelines for CPR recommend considering ECMO in patients who have an easily reversible event and have had excellent CPR [11, 12].

Although ECPR may be beneficial for OHCA patients, there are many complications associated with cannulation, such as bleeding, ischemia of ipsilateral extremities, and vascular injury [13]. Approximately 10-20% of patients who underwent ECMO for cardiac and respiratory failure experienced complications from cannulation [13]. Moreover, while both ultrasound and fluoroscopy can facilitate ECMO cannulation in cases of cardiac or respiratory failure [14, 15], there is no reliable evidence to support which cannulation method is better in ECPR. The Extracorporeal Life Support Organization (ELSO) recommends a cut-down method for cannula insertion as the first choice in ECPR cases because of no pulsation at the femoral artery [16]. Percutaneous cannulation is only recommended in cases where access to the vessels exists prior to CPR [16]. However, the percutaneous cannulation method has the advantage of speed, which is a very important factor in OHCA prognosis [14].

This study aims to assess the effect of two percutaneous cannulation methods (using ultrasound and fluoroscopy versus using ultrasound alone) on complication incidence and time to ECMO start in ECPR for OHCA.

We investigated the effect of ultrasound- and fluoroscopy-guided cannulation on the incidence of complications and time to ECMO start in ECPR for OHCA patients in a single-center retrospective observational study. Ultrasound- and fluoroscopy-guided cannulation did not delay the time to ECMO start and was associated with lower incidence of complication even after adjusting for several confounders.

The combination of ultrasound- and fluoroscopy-guided cannulation was associated with reduced complication incidence. For respiratory or heart failure, cannulation complication incidence in veno-arterial or veno-venous ECMO was approximately 10–20% in previous studies [13, 17‐21], whereas the incidence of complication for ECPR cannulation was approximately 25–60% [5, 22‐25], which is relatively high. This difference in complication incidence probably results from urgency associated with cannulation in ECPR, unlike other indications. In our study, the overall incidence of complications was 27%, which is similar to that seen in previous studies [5, 22‐25]. Moreover, percutaneous cannulation with ultrasound and fluoroscopic guidance appears to be a safer approach in ECPR cases, with only a 10% complication incidence. Ultrasound can allow secure puncture of femoral vessels, while fluoroscopy can prevent aberration and kinking of the guiding wire at the transparent cannulation site when the puncture site is dilated [14]. These points indicate that ultrasound- and fluoroscopy-guided cannulation contributed to reduce the incidence of complications.

Time from hospital arrival to ECMO circuit start was almost the same in the two groups. Survival rate of OHCA decreases as each minute passes [26]; therefore, time to initiation of ECMO circuit is a very important prognostic factor in ECPR [6, 24, 27, 28]. Mean time from hospital arrival to implementation of ECMO varied from 19 to 40 min in previous studies [5, 22, 29], whereas the median time was 17 min in both groups in the present study. A percutaneous approach with fluoroscopy and ultrasound is more complicated due to device operation. However, this complexity and potential risk of delay in cannulation seems to be reduced or eliminated by reducing the number of punctures and increasing the rapid and smooth dilation of the cannulation site [30]. Percutaneous cannulation with ultrasound and fluoroscopy guidance took less time in ECPR than percutaneous cannulation with ultrasound alone.

In the present study, only a percutaneous approach cannulation method was evaluated, despite ELSO recommendations [16]. However, a percutaneous approach is more often utilized, according to previous studies [5, 21, 22, 24, 31, ]. The Seldinger technique is adapted for insertion of large-diameter cannulas through the sequential use of several dilators of increasing size. The main advantage is a reduced risk of bleeding, and disadvantages include potential risk for displacement of a guiding wire, resulting in vessel injury or perforation, and difficulty in ensuring intraluminal placement [14]. Moreover, performing cannulation under resuscitation conditions is a major challenge. Detecting the target vessels under hypodynamic circulatory conditions is much more difficult [30]. Imaging modalities, including ultrasound and fluoroscopy, can overcome most of the limitations of a percutaneous approach [14]. Ultrasound can be used to determine vessel location and fluoroscopy can allow detection of incorrect placement of a guiding wire and cannula before perforation or other injury occurs. Thus, our practice includes using imaging during all phases of cannulation whenever possible, including vascular access, guiding wire insertion, and cannula placement.

The present study has several limitations. First, confounders such as coagulability and platelet count were not adjusted for, as these laboratory tests were performed after ECMO initiation. Since these laboratory test results were obtained after heparin administration and a centrifugal pump start, coagulability and platelet count were probably affected. Therefore, we adjusted anticoagulant or antiplatelet medication use as a surrogate marker of coagulability. Second, the number of physicians involved in ECPR, which might influence the outcome, could not be obtained from electronic medical records. We attempted to adjust for this possible confounder using time period, which is associated with the number of physicians. Third, complications associated with cannulation and time to ECMO start, not survival or neurologic outcome, were the outcomes assessed. However, bleeding complications surrounding ECMO are a major problem in managing post-cardiac arrest syndrome. Patients who experience cardiac arrest face several bleeding risks such as post-cardiac arrest syndrome, therapeutic hypothermia, and anticoagulation therapy [32‐34]. Thus, successful cannulation without complication is an important and relevant outcome in managing OHCA patients with ECPR. Lastly, this study is a retrospective before-after study. Management of post-cardiac arrest syndrome may have changed in the elapsed time. At the time that this study was conducted, 2010 AHA or ERC CPR guidelines were recommended, and we consistently treated patients with OHCA based on those guidelines. In addition, physician skills might influence our results. Further investigation for seeking the best cannulation method for ECPR is needed.

In ECPR for OHCA patients, a combination of ultrasound- and fluoroscopy-guided cannulation is associated with a lower incidence of cannulation complication than ultrasound only-guided cannulation, without delay in extracorporeal circulation start. This method can contribute to safer management of post-cardiac arrest syndrome.