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Failed intubation in the district hospital.

The twin potential consequences of failed tracheal intubation are the onset of hypoxia and emergence of the patient from the anaesthetic. The former may result in hypoxic brain injury or cardiac arrest and death of the patient, while the latter may impair conditions for effective management of the situation. Thus, when tracheal intubation has failed, the primary objective of resuscitation is to establish ventilation by any other means so as to ensure continued oxygenation of the patient.

The first step at this point is to revert back to manual ventilation with a facemask and 100% oxygen to ensure oxygen saturation is above 90%. This will allow an opportunity to re-appraise the situation and formulate the next plan of action, i.e. to proceed with the surgery or awaken the patient and postpone. If the decision is made to proceed, the anaesthetic will have to be topped up, not least to assure patient comfort but more importantly to optimise conditions for further airway manipulations.

If on the other hand it is decided to abort the procedure, the patient is allowed to emerge and the procedure rescheduled or other options considered, e.g. local, regional or plexus anaesthesia. If short-acting drugs had been used (propofol, suxamethonium, alfentanil) the patient can be expected to resume spontaneous ventilation shortly. The use of long-acting drugs such as non-depolarising neuromuscular blockers, on the other hand, will require that the patient is manually ventilated for a considerably longer period before spontaneous resumption of breathing or until it is safe to reverse the muscle relaxants (about 20 minutes for most).

Difficult facemask ventilation may improve with simple manoeuvres such as neck extension, jaw-thrust or placement of an oral airway. If there is no improvement, call for help and employ a two-person technique where one maintains the airway while the other takes over manual ventilation of the patient. If this still does not resolve the problem, insert a laryngeal mask airway while also excluding other causes of difficult ventilation such as laryngospasm or bronchospasm.

A secondary attempt at intubating the trachea implies that surgery cannot be postponed and that it can only be safely done with a tracheal tube in place. If help comes in the form of a more experienced colleague, another attempt at intubating the trachea with the aid of a rigid laryngoscope may be justified. This, however, is only appropriate where long-acting agents have been used, because of the need to avoid further doses of muscle relaxants when dealing with an already compromised airway. A more preferable option is the placement of an intubating laryngeal mask airway (ILMA: Fastrach) and subsequent use thereof to intubate the trachea. There is good evidence in the literature of successful placement of this device even by inexperienced personnel. (1,2) Even if intubation through the mask is unsuccessful the patient will still have a dedicated airway in place that allows positive pressure ventilation. In the absence of the ILMA the classic laryngeal mask airway (LMA) has also been used as a conduit for tracheal intubation. (1,3,4) There are however conflicting data about the success of this technique, thus prompting the Diffi cult Airway Society of the UK not to recommend its use in this setting. (5) Its effectiveness as an aid to intubation should improve if used in conjunction with a lighted stylet (Trachlight). (4,6,7)

Blind tracheal intubation with the use of a solid or hollow tracheal tube guide (e.g. stylet, gum elastic bougie or tube exchanger) is to be discouraged unless undertaken by an experienced practitioner in a stable, well-oxygenated and easily ventilated patient because it not only exposes the patient to further risk of hypoxic injury, but it may also contribute to deteriorating conditions by worsening tissue trauma, bleeding and airway oedema.

Whereas the flexible fibreoptic bronchoscope (FOB) features prominently in various published guidelines and algorithms for difficult airway management, it is useless in inexperienced hands during an emergency and will not be discussed any further. (3,5,6,8,9)

If secondary attempts at intubation have failed, the next step is to maintain oxygenation and ventilation with the dedicated airway device in place (ILMA or LMA) while preparing to awaken the patient or proceed with emergency surgery. It is important to recognise the risk of aspiration of gastric contents in emergency patients whose airways are secured with a LMA. The use of a ProSeal LMA as the dedicated airway device in patients at increased risk of aspiration will mitigate this risk. (5,10) An alternative device is the oesophageal-tracheal combined tube (Combitube), which not only provides a reliable seal against regurgitation, but also allows effective positive pressure ventilation; it can be used as a conduit for secondary tracheal intubation and placement in either oesophagus or trachea will allow ventilation. (1,4,11)

Failure of ventilation and ensuing hypoxia despite the techniques described is an indication for an invasive rescue technique. (4,5,8,9,11) A number of user-friendly cricothyrotomy kits are available on the market, but in the absence thereof surgical cricothyrotomy is possibly the most effective alternative (stab incision of skin and cricothyroid membrane and placement of a cuffed ID 5.0 mm ET tube). The use of intravenous catheters for needle cricothyrotomy is fraught with complications and not particularly effective.

In conclusion, every operating theatre complex should have a diffi cult airway trolley with the fewest possible alternative devices with which every practitioner is familiar.

(The reader is referred to the website of the Diffi cult Airway Society of the UK for a simplified management algorithm: http:// www.das.uk.com.)

The unanticipated diffi cult airway trolley should include the following:

* failed intubation airway algorithm chart

* intubating laryngeal mask airway (complete sets of different sizes)

* ProSeal laryngeal mask airways with appropriately sized nasogastric tubes (or intubation catheters) for suction through the oesophageal port

* Combitube (small adult size)

* Trachlight

* nasal RAE tracheal tubes or microlaryngeal tubes (MLT)

* cricothyroid cannula set

* surgical cricothyrotomy kit.

Wong EK, Bradrick JP. Surgical approaches to airway management for anaesthesia practitioners. In: Hagberg CA, ed: Handbook of Difficult Airway Management. Philadelphia: Churchill Livingstone 2000; 209-210.

Further reading

Heidegger T, Gerig HJ. Algorithms for management of the difficult airway. Curr Opin Anaesthesiol 2004; 17(6): 483-484.

Hung O, Murphy M. Unanticipated difficult intubation. Curr Opin Anaesthesiol 2004; 17(6): 479-481.

Scrase I, Woodard M. Needle versus cricothyroidotomy: a short cut. Anaesthesia 2006; 61: 962-974.

References

(1.) Dorges V, Wenzel V, Knacke P, Gerlach K. Comparison of different airway management strategies to ventilate apneic, nonpreoxygenated patients. Crit Care Med 2003; 31(3): 800-804.

(2.) Choyce A, Avidan MS, Shariff A, et al. A comparison of the intubating and standard laryngeal mask airways for airway management by inexperienced personnel. Anaesthesia 2001; 56: 357-360.

(3.) Langeron O, Amour J, Vivien B, Aubrun F. Clinical review: management of difficult airways. Crit Care 2006; 10 6): 243.

(4.) Foley LJ, Ochroch EA. Bridges to establish an emergency airway and alternate intubating techniques. Crit Care Clin 2000; 16(3): 429444.

(5.) Henderson JJ, Popat M, Latto IP, Pearce AC. Difficult Airway Society guidelines for management of the unanticipated difficult intubation. Anaesthesia 2004; 59: 675-694.

(6.) Crosby ET, Cooper RM, Douglas MJ, et al. The unanticipated difficult airway with recommendations for management. Can J Anaesth 1998; 45(7): 757-776.

(7.) Agro F, Hung OR, Cataldo R, et al. Lightwand intubation using the Trachlight: a brief review of current knowledge. Can J Anaesth 2001; 48(6): 592-529.

(8.) Practice Guidelines for Management of the Diffi cult Airway: An updated Report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2003; 98: 1269-1277.

(9.) Berkow LC. Strategies for airway management. Best Pract Res Clin Anaesthesiol 2004; 18(4): 531-548.

(10.) Cook TM, Hommers C. New airways for resuscitation? Resuscitation 2006; 69 (3): 371-387.

(11.) Combes X, Le Roux B, Suen P, et al. Unanticipated diffi cult airway in anesthetized patients: prospective validation of a management algorithm. Anesthesiology 2004; 100 (5): 1146-1150.
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Title Annotation:More about ... Anaesthetics
Author:Rantloane, J.L.A.
Publication:CME: Your SA Journal of CPD
Article Type:Report
Geographic Code:6SOUT
Date:Mar 1, 2008
Words:1331
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