Reperfusion Strategies in Patients With High-Risk Acute Pulmonary Embolism Needing Extracorporeal Membrane Oxygenation Support: A Systematic Review

Abstract

The probe (L15-7io; Philips, Amsterdam, Netherlands) used by the authors is marketed for vascular and intraoperative use. Even though this probe definitely can be used for vascular access (and certainly we have done so for many years), this is not its primary use.We think this is a crucial point because this probe, unlike (most) other commercially available products specifically designed for vascular access, lacks any guidance marker on its surface. As previously demonstrated, guidance markers are now physically available on the probe and virtually on the screen and have been shown to improve success of vascular cannulation. 2 Interestingly, in one of the studies cited by the authors, a "home-made" marker (created by using a stitch) was described. The OOP approach was superior in terms of first-attempt success rate compared with the IP approach in that study. 3 The IP and OOP techniques have different characteristics and are not, in our opinion, mutually exclusive. For example, OOP imaging undoubtedly provides an better lateral resolution, and this is especially useful for narrow vessels. In addition, when there are calcifications on the upper side of the artery (eg, from 11-to-1 o'clock), the artery can be approached and cannulated safely from the side (eg, from 10 or 2 o'clock). Unfortunately, this requires excellent needle-manipulating skills, and the unexperienced provider can find it more difficult and be less successful compared with a more experienced provider. Another issue that can prevent successful cannulation and also cause damage to surrounding structures is the inability to keep track of the needle tip. In fact, if the ultrasound beam is not aligned with the tip, then the needle shaft, which will appear as a bright point on the screen, similarly to its tip, can be mistaken for the tip, which in turn will be invariably deeper than expected and not on the screen.On the other hand, the IP technique provides a better view of the needle, especially the tip, 4 and is in concurrence with some anesthesiologists that the needle be viewed at all times. Unfortunately, in the case of small, narrow, or tortuous vessels (or in neonates/children), it is not uncommon for the novice to image the vessel in what is not its larger longitudinal dimension (ie, not along the plane that cuts the vessel vertically from 12-to-6 o'clock). Alternatively, even when a correct image is obtained, the needle can be slightly off plane and still look acceptable on the screen to the inexperienced user. Both of these situations can result in a lateral cannulation of the vessel. This lateral cannulation is not the "side-to-middle," intentional, and sought-after cannulation previously described in case of surface plaques but rather an "along-the-side," unintentional cannulation, which could result in inability to cannulate or even dissection of the vessel.For many years we have used a combined, hybrid approach whereby the artery initially is imaged with the OOP technique and the needle tip is advanced until it lies on the vessel at the 1...