Access Denied? A new perspective on the cannula call

The anaesthetic team are responsible for providing routine and emergency cover, both in and out of hours, in multiple areas of the hospital. This includes but is not limited to, theatres, intensive care units, emergency departments, maternity, cardiac intervention, interventional radiology, airway support for the base hospital, and on occasion, transfers between sites. Vascular access is not a routine service that is provided by most anaesthetic departments and is not feasible to add this to the list of expected responsibilities of the anaesthetist. It is, however, anecdotally noted to be the right thing to do, when clinical workload allows, to assist a colleague from another specialty.

The rationale often offered with regards to calling anaesthetics is that should we be unable to secure venous access peripherally, central access may be the logical next step. Whilst we would agree with this in some circumstances, it adds frustration to other specialties when we suggest that a senior team member try in the first instance. As well as the most senior member of the clinical team being placed to determine whether the patient would be suitable for invasive access, they also may be more experienced in gaining peripheral access in less straightforward patients. This has benefits for patients by reducing unnecessary, higher-risk procedures.

In these authors’ personal experience, these ‘tricky’ patients referred to us often do not require any specialist equipment and access can be successfully secured with patience and doing basic techniques well. As pressure on the NHS and with that, anaesthetic services, increases, it is likely that as a specialty we will be unable to provide a sustainable vascular access service, as indeed there often is not one.

Instead, these authors propose that anaesthetists could be using these calls to our advantage to educate other medical practitioners in effective techniques. This may help to reduce demand and make the service accessible for those patients in true need.

All avenues of medical practice require further learning. If the anaesthetist is perceived as the most qualified to perform difficult cannulation, then perhaps they are the most appropriate to teach techniques for difficult peripheral vascular access. This holds true in the authors’ opinion as most “cannula calls” we have attended, have required nothing more than a manual blood pressure cuff, an abundance of patience, and in some circumstances, basic skills with an ultrasound scanner. None of these things are specific to an anaesthetist and are simple skills to develop if time is taken to teach and for supervised practice.

Miller's Pyramid

We propose a multi-step mastery education system, using the top two layers of Miller’s pyramid of learning [1]; “shows how” and “does” to ensure adequate learning. Miller’s Pyramid is a framework developed to inform assessment of clinical competency, utilising four steps as demonstrated in the diagram below (Fig. 2).

Direct observation and feedback in simulation and finally in practice are the final stages of this process “shows how” and “does,” allowing assessment of technical and interpersonal skills to prove competency. Examples of assessment at each stage include MCQ assessments (factual recall) for “knows,” case presentations for “knows how,” simulation and OSCEs for “Shows how” and supervised learning events (e.g., direct observation of procedural skills or DOPS) in the workplace, all of which show progression from Novice to Expert.

How to improve peripheral vascular access training

Firstly, an initial clinical teaching session, using cannulation mannequins supervised by “expert” trainers (such as anaesthetists), enabling supervised practice and critique of technique. This may be best placed at Foundation Year 1 (FY1) induction as these are the people most likely to be called first to cannulate difficult patients.

Progression through this course of learning could potentially take the form of supervised ultrasound scanning on live volunteer models, which would allow participants to develop an understanding of the relevant features on sonoanatomy e.g., ability to correctly identify arteries and veins from surrounding tissue structures.

Finally, as part of this initial stage of learning, phantom needling sessions could be arranged to allow for supervised practice and ensure safety of needling technique.

However, all but the first step would be progression, and focus should be on ensuring that the basics are done well one hundred percent of the time. We also acknowledge that we are privileged that most anaesthetic and intensive care, as well as emergency departments, have an ultrasound scanner readily available, whilst other areas do not have access to one at all. This further validates the point that basic techniques and ways to optimise difficult cases are the most important aspect.

This would naturally lead to the pinnacle of Miller’s Pyramid; “does.” If the basics have failed the referrer, and an anaesthetist was called, we would propose the anaesthetist who attends, not-withstanding in an emergency (when patient safety and care is obviously paramount) acts as a facilitator, rather than “doing it for them". The anaesthetist could critique technique, offer tips, supervise ultrasound practice if required, and allows a final attempt to cannulate by the referrer, before taking over and attempting themselves. In this situation, the anaesthetist can talk through and demonstrate any “tricks” they utilise to secure IV access.

We would hope that if anaesthetists utilised these requests as training opportunities, the basics would be done well consistently, reducing primarily the number of failed attempts, thus reducing the risks associated with multiple punctures. Similarly, although there is an initial time investment, there would be significant benefits to patients and the anaesthetic workforce alike.

Patient care would be improved from more timely treatment by decreasing the time taken to provide medication or fluids they urgently need. Moreover, we anticipate that request numbers would reduce, ensuring that anaesthetists are only called for truly difficult ones, where other methods of access are genuinely likely to be considered.

Conclusion

Anaesthetists can play a key role in improving peripheral vascular access training for other medical practitioners. By utilising Miller's Pyramid, we can develop a multi-step mastery education system that will help to ensure that all healthcare professionals have the skills and knowledge they need to provide safe and effective vascular access.

Susan Baird CT3 , Altnagelvin Hospital, Londonderry

Fearghal O’Brien CT2 , Belfast City Hospital, Belfast

References

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