History of Royal Perth Hospital (RPH)
Established in 1829, RPH is Western Australia’s longest-serving hospital and renowned for contributing to innovation and excellence in medical research and patient care. It has one of the busiest Emergency Departments in Australia and the second biggest trauma workload in the country. As a premier teaching hospital, RPH has a number of joint appointments with the universities and has built a global reputation, hosting many significant medical breakthroughs including Nobel Prize-winning discoveries. RPH is internationally recognized for its airway training, particularly in relation to the Can’t Intubate, Can’t Oxygenate (CICO) scenario.
RPH is a 450-bed hospital, which provides an extensive range of services including:
- adult major trauma,
- complex and elective surgery including ENT and maxillofacial surgery, and
- highly specialized surgical services.
RPH offers 4 anesthetic airway fellowships per year, each of 6 months duration. This is a highly sought-after fellowship internationally, and places are often reserved many years in advance. The RPH airway fellowship is truly unique because of the opportunity to become proficient in performing and teaching percutaneous emergency oxygenation (PEO) techniques in the RPH Wet Lab. The airway fellows are responsible for both the administration and teaching of the Wet Lab on a weekly basis. Fellows also provide other airway education to anesthesia trainees, critical care trainees, and allied health staff, with involvement in developing teaching resources to meet the needs of these specific groups. This training is often undertaken in our “dry lab” simulation room and encompasses basic competency training, video laryngoscope use, and fiberoptic intubation training. Opportunities also arise to teach airway management techniques interstate and internationally.
As with any tertiary hospital, clinical workload is varied. The airway fellow is regularly rostered to lists that provide experience in complex airway management and fiberoptic intubation. This includes exposure to patients with significant subglottic stenosis, and those undergoing airway surgery. Through its maxillofacial service, and as the state trauma center for Western Australia, RPH also offers exposure to patients with acute airway compromise. The airway fellowship also allows motivated fellows the opportunity to undertake high quality research projects and clinical audits1–3.
The RPH “Wet Lab”
As a core component of the airway fellowship, the fellows over the last 14 years have played a significant part in developing the wet lab as it is today, and in the formulation of the Royal Perth CICO Algorithm (Fig. 1).
Following an airway-related death in 2001 in the recovery room at RPH recommendations were made to develop equipment and training for the management of the “CICO” scenario. Training initially took the form of both manikin-based teaching (dry lab) and emergency airway training using a cadaveric sheep model. At the end of 2004, following ethical approval, the fidelity of the simulation was significantly improved by switching to using a live animal model. The wet lab runs every week, 48 weeks a year and is attended by anesthetists, ICU, and ED physicians. Wet lab training is entirely voluntary, with additional dry lab training provided for those individuals who do not wish to partake in the wet lab component.
The sheep are primarily used for emergency airway training, although venesection for agar plate production preceded airway training by many years and continues to this day. The animals are also utilized to support other studies and modes of medical training, in line with the National Health and Medical Research Council principle of reduction.
The wet lab resembles an operating theater. There is an anesthetic machine, piped gases, standard monitoring, an airway trolley, and an ultrasound machine. The animals are anesthetized by veterinary technicians as per veterinary anesthesia guidelines. Pulse oximetry, end-tidal carbon dioxide, electrocardiogram, and intra-arterial blood pressure waveforms are displayed. Immediately before starting the training session, a degree of upper airway obstruction is created and the animal is allowed to desaturate, simulating the CICO scenario.
Manikin and cadaveric training, although useful, is a limited substitute for the real life CICO situation. Cadaveric training is likely to be superior to manikin based training, but the major drawback is a bloodless field. Replicating an operating theater environment, using live anesthetized sheep and running the training as a genuine CICO situation has the benefit of allowing the trainee to practice taught skills in real time. They also have the benefit of using real tissue, observing physiological responses, and gain an understanding of the “human factors” issues surrounding this critical incident. This model also enables validation of the equipment recommended for managing the CICO situation. The animal model cannot completely reproduce the situation that would arise in a human subject, but a sheep model is probably the closest practicable model available4.
The development of an algorithm for the adult CICO scenario
The CICO scenario is a relatively rare event with an estimated incidence of ∼1 in 5000 to 1 in 10,000 General Anesthetics5,6. Although a rare event, over half of experienced anesthetists surveyed report to encountering this scenario at least once in their career7. We believe it is a professional responsibility to be prepared for such an event.
All algorithms for the management of a CICO situation advocate either a needle-Seldinger, cannula or a surgical (scalpel) technique. Timely progression through emergency algorithms is impeded when the operator is faced with pathway decisions, or choices, rather than prescriptive stepwise guidance (such as the ALS algorithm)8.
Percutaneous emergency oxygenation (PEO) is a term we have introduced to allow clearer description of procedures undertaken through the neck to achieve oxygenation in a critical event. The Difficult Airway Society (DAS) has developed the term Front of Neck Airway (FONA) to describe procedures to achieve oxygenation via the neck9. These 2 terms can be used interchangeably.
The body of evidence for specific PEO techniques in the CICO scenario is not strong, and a human based, high-quality research on this is not feasible. Our experience in the wet lab over the last 12 years has allowed us to observe thousands of attempts at cannula, needle-Seldinger, or scalpel techniques in a stressful, simulated environment. This has allowed us to produce an algorithm that aims to provide the best chance of successful intervention.
Observation of candidates in the wet lab revealed that when presented with a treatment decision, individuals may struggle to make the choice with a consequent delay to commencing oxygenation. Therefore, it is important the initial technique for PEO is applicable to all CICO situations, regardless of patient factors10.
The skills of the typical anesthetist are in favor of a cannula or needle-Seldinger technique over a scalpel technique. Using a cannula in the first instance every time can reduce the human factors obstacle to making the decision to proceed at the beginning of the algorithm. In many situations, there will be a “mental hurdle” to commencing PEO11. In our experience, for anesthetists, inserting a needle or cannula into someone’s neck as a first step represents less of a hurdle than making an incision with a scalpel.
CICO scenarios may present with patients having normal anterior neck anatomy, or more difficult impalpable anatomy12. The use of a cannula first is applicable to all cases, regardless of anterior neck anatomy, and even if upper airway obstruction is present. With appropriate training, and correct equipment the cannula technique has a high success rate and the ability to achieve rapid oxygenation10. In a CICO scenario the priority should be to treat life-threatening hypoxia, rather than techniques that prioritize ventilation (eg, high pressure jet ventilation), or a cuffed airway. With a cannula technique, oxygenation can be rapidly achieved using a low cost flow-regulated oxygen delivery device, with no attempt to ventilate10. Following oxygenation and stabilization, the anesthetist then has options; to convert to a cuffed airway using a Melker kit, wake the patient, or consider additional upper airway techniques to secure a conventional intubation.
Cannula versus needle-Seldinger
Both a cannula and needle-Seldinger technique work to the specific skill set of the anesthetist, however, as mentioned above, the priority in a CICO situation should be to provide rapid oxygenation, rather than ventilation.
Although a needle-Seldinger technique can provide a wide-bore cuffed airway, it likely incurs a significant delay to initial oxygen delivery in comparison to a cannula technique. In addition, a Seldinger technique is technically more challenging. We have found that under the extreme pressure of critical hypoxia in a CICO scenario, our participants struggled with the fine motor control required for the needle-Seldiner techniques, and failed to trouble shoot any difficulties. In going for a cannula first, the fact that the patient has received oxygen and is stabilized increases the ease of performing the Seldinger technique (Melker conversion). In this way we achieve safe simple and fast oxygenation as well as achieving a cuffed airway10.
Cannula versus scalpel
As already mentioned, an anesthetists skills set with, and willingness to use a scalpel blade is not one of our strong points. NAP4, a National Audit from the United Kingdom looking at airway complications has often been quoted as showing that scalpel techniques are better than cannulas13. At RPH we fell that the NAP4 data simply confirms anesthetists are not proficient at techniques for which they are unprepared in terms of training or equipment choice and availability. This explains many of the failed cannula techniques. Conversely, the relative success with scalpel techniques reflects ENT surgeons performing tracheostomies, a procedure for which they are rigorously trained. Nevertheless, in some instances surgical tracheostomies required over 30 minutes to place4,11,12,14.
One of the notable problems we found when we first started training with the live animal model was the difficulties that active bleeding introduces. Making even a small incision in the neck to access the airway can cause bleeding to a degree that makes visualization of structures difficult to impossible. This is even more of an issue in the neck where anatomy is not palpable, and runs the risk of major vessel damage. This can lead to a failure in continuation, and or success of the PEO attempt15.
From our experience in the wet lab, if a scalpel technique is performed first and fails, significant airway soiling and tissue destruction can preclude subsequent cannula attempts. This means the scalpel first pathway is in practice a scalpel only pathway16. A cannula technique is less tissue destructive, and a cannula attempt does not significantly impair subsequent cannula attempts.
The endpoint of successful placement of a cannula in the airway is identified by free aspiration of air with no residual vacuum in the syringe. This definitive end point gives 2 important benefits. First, rapid identification of success allows rapid oxygenation without confusion, and second rapid identification of failed attempts allows you to quickly abandon a failure, allowing multiple attempts within a short space of time. In addition, if cannula attempts are unsuccessful, subsequent attempts with a scalpel technique are not impaired. Hence, a cannula first approach leaves the door open for a subsequent scalpel attempt if required.
In conjunction with anesthetists and otolaryngology surgeons from Princess Margaret Hospital in Perth, the wet-lab team has also used a small animal model to simulate a pediatric CICO scenario revealing a cannula technique success rate of 60%17. Furthermore, a comparison of Cook-Melker (CM) and scalpel bougie (SB) finding a success rate of 100% and 75%, respectively18. However, significant airway damage was noted with both the CM and the SB technique with the latter being more pronounced.
Ongoing airway research
Airway Fellows are encouraged to participate in ongoing airway research within the department, and to develop their own areas of research interest. The department has a strong research group which overlaps with the airway faculty. Currently, a number of airway-related projects are active within the department. Apnoeic oxygenation has been a strong focus of previous airway fellow research, particularly the technique of buccal RAE tube oxygenation3. A current study is looking at the physiological processes that underlie this technique. In addition to the theater workload, RPH is fortunate to have a busy anesthetic preassessment service. This has allowed for a project investigating anatomic parameters that may be important in a CICO scenario. The Wet Lab also provides some unique opportunities for research including comparison of techniques used in PEO. In addition, there is a study underway using a novel technique to definitively confirm endotracheal tube position. As well as these major research projects, there is ample scope for smaller audits and fellow-lead investigations.
The RPH airway fellowship has been considered the highlight of many of the fellows anesthetic careers. A significant number of previous fellows have gone on to take up leadership roles in airway management, teaching and research across the world.
The authors would like to acknowledge the work of all previous airway fellows, and the continued support for this fellowship from the Department of Anaesthesia at Royal Perth Hospital.
Conflict of interest disclosures
The author declares that there is no financial conflict of interest with regard to the content of this report.
1. Heard AMB, Lacquiere DA, Riley RH. Manikin study of fibreoptic-guided intubation through the classic laryngeal mask airway with the Aintree intubating catheter vs the intubating laryngeal mask airway in the simulated difficult airway. Anaesthesia 2010;65:841–7.
2. Dinsmore J, Heard AMB, Green RJ. The use of ultrasound to guide time-critical cannula tracheotomy when anterior neck airway anatomy is unidentifiable. Eur J Anaesthesiol 2011;28:506–10.
3. Heard A, Toner AJ, Evans JR, et al. Apneic oxygenation during prolonged laryngoscopy in obese patients: a randomized, controlled trial of buccal RAE tube oxygen administration. Anesth Analg 2017;124:1162–7.
4. Greenland KB, Bradley WPL, Chapman GA, et al. Emergency front-of-neck access: scalpel or cannula—and the parable of Buridan’s ass†. Br J Anaesth 2017;118:811–4.
5. Kheterpal S, Martin L, Shanks AM, et al. Prediction and outcomes of impossible mask ventilation: a review of 50,000 anesthetics. Anesthesiology 2009;110:891–7.
6. Nagaro T, Yorozuya T, Sotani M, et al. Survey of patients whose lungs could not be ventilated and whose trachea could not be intubated in university hospitals in Japan. J Anesth 2003;17:232–40.
7. Wong DT, Lai K, Chung FF, et al. Cannot intubate–cannot ventilate and difficult intubation strategies: results of a Canadian National Survey. Anesth Analg 2005;100:1439–46.
8. Resuscitation Council (UK). Resucitation Guidelines. 2010. Available at: www.resus.org.uk
. Accessed May 5, 2017.
9. Frerk C, Mitchell VS, McNarry AF, et al. Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. Br J Anaesth 2015;115:827–48.
10. Heard AM. Percutaneous Emergency Oxygenation Strategies in the “Can’t Intubate, Can’t Oxygenate” Scenario. Perth, Australia: Smashwords; 2013.
11. Timmermann A, Chrimes N, Hagberg CA. Need to consider human factors when determining first-line technique for emergency front-of-neck access. Br J Anaesth 2016;117:5–7.
12. Kelly FE, Cook TM. Front of neck airway: the importance of the correct (obese) models and (trained) participants in study design. Anesthesia 2017;126:986–987.
13. Cook TM, Woodall N, Frerk C. The NAP4 Report: Major Complications of Airway Management in the UK. London: The Royal College of Anaesthetists; 2011.
14. Heard AM, Debenham E. The Can’t Intubate Can’t Oxygenate scenario (CICO). ANZCA Bulletin 2011;9:48–9.
15. Cranfield K, Gauntlett R. A Very Difficult Airway. London: Obstetric Anaesthetists Association; 2016.
16. Heard A, Dinsmore J, Douglas S, et al. Plan D: cannula first, or scalpel only? Br J Anaesth 2016;117:533–535.
17. Stacey J, Heard AMB, Chapman G, et al. The “Can’t Intubate Can’t Oxygenate” scenario in Pediatric Anesthesia: a comparison of different devices for needle cricothyroidotomy. Pediatr Anesth 2012;22:1155–8.
18. Prunty SL, Aranda Palacios A, Heard AM, et al. The “Can’t Intubate Can’t Oxygenate” scenario in pediatric anesthesia: a comparison of the Melker cricothyroidotomy kit with a scalpel bougie technique. Pediatr Anesth 2015;25:400–404.