Emergency cricothyroidotomy: training is paramount and oxygenation is the aim

Abstract

We read with great interest Dimitriadis and Paoloni’s [1] study examining the use of four methods of cricothyroid access. The ‘can’t intubate, can’t ventilate’ (CICV) scenario is a rare but potentially devastating one and research aimed at improving its management is welcome. The study raises issues that need highlighting. The authors correctly point out that training in the management of the CICV scenario is likely to have been remote in time and poorly remembered by clinicians. It would be easy for the reader to ignore this issue and concentrate instead on the authors’ findings regarding the optimum device to use without refresher training. The anaesthetic community must not lose focus; training aimed at managing the CICV situation should be the priority [2]. Unfortunately, the authors make no mention of narrow-bore cannula (or ‘needle’) cricothyroidotomy. In a study aimed at determining which method of emergency cricothyroidotomy is the easiest and quickest to perform without refresher training, we find this surprising. Although the study’s participants were emergency physicians, the readership consists predominantly of anaesthetists. Most anaesthetists are more familiar with the use of simple intravenous cannulae than devices such as the Quicktrach (VBM Medizintechnik GmbH, Sulz, Germany) or Minitrach (Smiths Medical Ltd, Hythe, UK) and insertion involves fewer steps. The skills of anaesthetists also favour the use of a cannula over the use of a scalpel [3]. Moreover, intravenous cannulae are ubiquitous in the operating theatre and Emergency Department. The 14G Insyte Cannula (Becton Dickinson UK Ltd, Oxford, UK) is ideally suited as its trochar is sharp and the cannula has a memory allowing the lumen to reform after kinking. Thus, cannula cricothyroidotomy is likely to be an easier and quicker technique for anaesthetists to use than the four techniques evaluated in Dimitriadis and Paoloni’s study [1]. Ideally cannula cricothyroidotomy should be followed by high pressure source oxygenation using a device such as the Manujet III (VBM Medizintechnik GmbH). We feel that such a device should be immediately available in areas where advanced airway management occurs, however oxygen tubing connected to a three-way tap, sourced from an oxygen cylinder or pipeline can maintain oxygenation and thus the patient’s life, if this is not available [4]. It is of course true that needle cricothyroidotomy followed by high pressure source oxygenation does not provide a cuffed large bore airway, an important endpoint in many CICV scenarios. However, the likelihood is that, when a clinician feels that emergency cricothyroid access is necessary, the patient will be critically hypoxic, and cardiac arrest will be imminent. The priority in this situation is rapid oxygenation and conversion to a cuffed airway is of secondary importance. To make an incision in the cricothyroid membrane with a device but then not use that device to oxygenate is to waste valuable time, with potentially fatal consequences. Once the patient has been re-oxygenated, conversion to a cuffed larger bore airway can occur using a Seldinger technique via the cricothyroid cannula. A further limitation of Dimitriadis and Paoloni’s study is that it was performed using an artificial model. Experience in the use of both live animal and artificial models for the CICV situation (personal communication, AMB Heard) makes us feel that plastic models positively discriminate towards large bore cricothyroidotomy cannulae and surgical techniques. For instance while the Quicktrach cuts and dilates easily through synthetic ‘tissues’ in artificial models, it is very difficult to insert through the skin and subcutaneous tissue overlying the cricothyroid membrane of live animals. Also, making a scalpel incision in synthetic tissue leaves a readily identifiable hole in the tracheal wall that is easy to dilate for surgical cricothyroidotomy; but in the live animal model the tissues move relative to each other, thus the hole is difficult to identify and may be obscured by blood. In summary we believe that it is not acceptable for the anaesthetic fraternity to accept the status quo of infrequent training in management of the CICV scenario. In addition we believe that, in this scenario, a narrow bore cricothyroid cannula is the device most likely to save the critically hypoxic patient’s life.