Real‐time ultrasound guidance for central venous access: a reply

We thank Wood and Scurr for their comments [1] on the Association of Anaesthetists Safe Vascular Access Guidelines [2]. Ultrasound-guided central venous access remains the gold standard and has been shown to improve success rates and to reduce complications, but we agree that there are some circumstances where ultrasound may not be either available or appropriate. Despite how portable and commonly available ultrasound machines have become, we have highlighted situations such as resource-poor settings, surgical emphysema and emergencies, where landmark techniques for central venous access may still have to be used. Wood and Scurr identify a population of patients with hypovolaemic shock in the prehospital environment, in which peripheral and intraosseous access is inadequate or impossible, and in whom they have considerable experience and success in the landmark insertion of subclavian vein devices [3]. They highlight reasons why ultrasound guidance may not be possible in these patients and where it may even delay insertion. They recognise that the subclavian vein is extremely resistant to collapse, even in severe hypovolaemia and in an upright position, because of the connections between the tunica adventitia of the vein and surrounding structures. This is also the case for the medial part of the axillary vein, as it becomes the subclavian vein. In specific circumstances, and in expert hands, landmark access to the subclavian vein remains an important route of central venous access. However, we would like to highlight the potential for thoracic trauma (e.g. clavicle or first rib fractures) to disrupt the usual anatomical landmarks. In most cases, we would still advocate the use of ultrasound for axillary/subclavian vein insertion. When done medially and close to the clavicle, the vein is usually patent even in hypovolaemic patients and there is now a considerable evidence base that ultrasound-guided access improves success rates and reduces complication rates [4, 5].