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20/04/2018

Coniotomie: Au moins 15 ml

Surgical cricothyrotomy: the tracheal-tube dilemma.

 
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L'emploi de tube trachéo d'au moins 5 mm voire 6 mm est requis pour permettre une ventilation alvéolaire optimale par coniotomie. Ce diamètre est adapté à celui de la membrane cricoïdienne. Cependant les auteurs du document présenté mettent en avant une taille insuffisante du ballonet qui ne permettrait pas une occlusion trachéale correcte. Une réponse est faite à leur interrogation. Il faut gonfler le ballonet avec au moins 15 ml d'air.
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Editor—In a recent issue of the British Journal of Anaesthesia, Higgs and colleagues1 published guidelines for the management of tracheal intubation in critically ill adults. I appreciate the authors' successful efforts for implementation of comprehensive guidelines to improve airway management and patient safety in the intensive-care-unit environment. In accordance with current evidence and expert opinion, the authors recommend an open surgical approach (surgical cricothyrotomy) for emergency front-of-neck access in adult patients. They highlight the benefits of this technique: it is fast, reliable, has a high success rate, and provides definitive access to the airway. After incision of the cricothyroid membrane, insertion of a tracheal tube via a bougie stylet is advocated. The use of tracheal tubes with an inner diameter (ID) of 5.0 or 6.0 mm is advised, presumably because of the dimensions of the cricothyroid membrane.

Insertion of ‘standard’ tracheal tubes with an ID of 5.0 or 6.0 mm generates a dilemma of potentially limiting the benefits of the surgical technique. The cuff diameter of a tracheal tube of ID 6.0 mm with a high-volume low-pressure cuff is 18–19 mm, or about 13 mm in a tracheal tube of ID 5.0 mm. The upper limits of normal for coronal and sagittal diameters of the trachea in men of 20–79 yr average 25–27 mm, and in women 21–23 mm. The disparity between the diameters of the inflated cuff and the trachea potentially generates a leak.

Insufflation of oxygen via a standard tracheal tube should provide sufficient oxygenation. But, further gains of a surgical approach with tracheal-tube insertion, such as confirmation of success by waveform capnography, protection against aspiration, and application of PEEP, are possibly impeded because of insufficient cuff seal. Thus, are standard tracheal tubes superior for this challenging scenario?

Given its advantages, surgical cricothyrotomy is the recommended technique in the ‘cannot intubate, cannot oxygenate’ scenario. To overcome the problem of leakage caused by the mismatch of small tracheal-tube cuff and tracheal diameters, we equip all cricothyrotomy kits for adults with micro-laryngeal tubes (MLTs) ID 5.0 and 6.0 mm (Rüsch® micro-laryngeal endotracheal tube; Teleflex Medical GmbH, Belp, Switzerland). Designed for laryngeal or tracheal surgery and patients with tracheal stenosis, these tubes offer smaller inner (5.0 or 6.0 mm) and outer (7.3 and 8.7 mm) diameters to provide better visualisation and access to the surgical site. But, the cuff diameter averages 31 mm, about the cuff diameter of a standard ID 8.0 mm tube. It is possible to place an ID 5.0 or 6.0 mm tube through the incision in the cricoid membrane, whilst simultaneously achieving a sufficient seal in adults, enabling positive pressure ventilation, sufficient expiration, capnography, etc. We have used this successfully in mannequin tests and in emergencies. I recommend routine use of MLTs instead of standard tracheal tubes for surgical cricothyrotomy procedures in adults, and encourage the authors to take these considerations into account for future updates of their excellent guidelines.

 

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Response to 'Surgical cricothyroidotomy-the tracheal tube dilemma'.

 

 

Tracheal tube Cuff diameters inflated using different volumes of air, (mm)-including diameter stated on packaging

Table 1Tracheal tube Cuff diameters inflated using different volumes of air, (mm)-including diameter stated on packaging
Tube inner diameter (mm) Stated cuff diameter (mm) 12 ml inflated (mm) 15 ml inflated (mm) 20 ml inflated (mm)
5.0 18 25 26 27
5.5 21 25 27 30
6.0 22 26 28 30

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