Retrograde tracheal intubation

Abstract

Cook et al. report airway rescue using a Proseal™ laryngeal mask airway paired with fibrescope-guided placement of an Aintree intubation catheter®[1]. They recognised that their patient had the ‘full house’ for airway problems, with recognised difficulties in facemask ventilation, tracheal intubation and subglottic cannulation. Their creative pairing of equipment is to the authors' credit, especially in the setting of airway rescue for a hypoxic, unstable patient. We suggest that there would have been a good case for awake definitive airway management in addition to the precautionary cricothyroidotomy given the anticipated airway difficulties noted. The authors mention that an awake, transnasal fibreoptic approach had failed on a previous occasion. This, we surmise, influenced the authors in their choice of cricothyroidotomy with jet ventilation under general anaesthesia as their first management option. We suggest a retrograde technique, a method that has received little recent attention in the realm of airway management. Retrograde approaches are fairly simple to perform under local or general anaesthesia, have a high safety profile and can succeed when other techniques fail. A retrograde approach, however, needs sufficient space around the patient's neck to allow airway cannulation via the cricothyroid membrane. Sanchez & Morrison give a useful description of the range of retrograde options available [2], including a method by which a retrograde approach is used with a fibrescope [3], which we describe below. After patient consent and preparation, including topical airway anaesthesia, a 16 G epidural needle is used to cannulate the airway through the cricothyroid membrane with the bevel facing rostrally. An angiographic guidewire of sufficient length (we use a Teflon coated wire, diameter 0.889 mm and 145 cm long; Medtronic Vascular, Danvers, MA) is threaded into the airway through the needle and usually protrudes out from the patient's mouth. A sufficient length of wire is pulled through the mouth, taking care not to pull the wire completely into the neck (a clip applied to the wire near the neck will prevent this). The guidewire is then passed into the working channel of a lubricated fibrescope loaded with a suitable tracheal tube. The guidewire allows the fibrescope to traverse the upper airway into the larynx until the fibrescope abuts the larynx at the level of the cricothyroid membrane. At this stage the guidewire can be pulled out, either rostrally or caudally through the neck. Choosing the former option may reduce lower airway contamination from the oral cavity. Once the fibrescope is no longer constrained by the guidewire it falls into the airway, allowing further advancement of the fibrescope into the tracheal lumen and subsequent passage of the tracheal tube. A modification to guidewire removal is to pull the guidewire rostrally until it lies in the trachea, when it can be advanced into the trachea, preserving a pathway for any further airway instrumentation. This method results in orotracheal intubation. Should nasotracheal intubation be required, an additional step prior to use of the fibrescope is needed to re-direct the guidewire from the oral to the nasal route. A suitable gastric tube is inserted into the patient's nose and lifted from their pharynx either digitally or by Magill's forceps so the tip now exits from the mouth. The guidewire is threaded into the tip of the gastric tube, re-directing the guidewire from mouth to nose, at which time the gastric tube can be removed from the patient. Retrograde techniques using a guidewire require that the wire be of sufficient length to traverse a patient's airway and the length of a fibrescope and central venous catheter wire are not suitable. Whilst there are other retrograde techniques available, we feel that pairing of guidewire to fibrescope has great merit, allowing visualisation of the intubation sequence.