Management of Difficult Face-Mask Ventilation
In patients with difficult face-mask ventilation (MV), the two-person approach and two-handed MV together with properly placed oropharyngeal and/or nasopharyngeal airways may overcome these difficulties and may provide adequate oxygenation and ventilation (25). The second person can help to achieve better mask seal, more effective jaw thrust, and positive-pressure ventilation.
There is no support by published evidence but common practice, that MV must be established and confirmed before administration of a neuromuscular blocking drug (NMBD), a claim to preserve the potential facility of awakening the patient when considered, but completely ignored when using traditional rapid-sequence induction. There is some evidence, that MV may become easier with neuromuscular blockade by solving the initial resistance to ventilation, particularly due to functional airway obstruction. This issue remains controversial but the current debate favors the early use of a non-depolarizing NMBD with rapid onset such as rocuronium (14, 45).
Although there is an association between difficult MV and difficult tracheal intubation, in some patients conventional tracheal intubation may be easy to perform; Kheterpal and co-workers (34) reported successful tracheal intubation even in patients with impossible MV, particularly when a NMBD was administered. Therefore, the Canadian expert working group (22) recommends a single conventional laryngoscopy (CL) and tracheal intubation attempt as a prudent first intervention before initiating backup ventilation strategies.
Expert working groups highly recommend laryngeal mask airways (LMAs) as backup devices for difficult MV (2, 11, 22, 32, 43); this issue was recently outlined by El-Orbany and Woehlck (25). The introduction of the classic LMA has revolutionized anesthetic practice and is one of the most important advances in airway management. LMAs have proved to be effective in establishing and maintaining a patent airway in most difficult MV and/or conventional tracheal intubation situations (18, 25, 41). In a recently published large evaluation of the classic LMA and the tracheal tube (TT) for securing the airway in patients requiring general anesthesia and positive-pressure ventilation for various surgical procedures, there were no differences in the rather rare incidence of pulmonary aspiration (9). For patients at high risk of pulmonary aspiration, the reusable LMA with an esophageal drain tube for gastric drainage, the ProSeal LMA, should be preferred as this LMA forms an improved seal and may offer a better protection (32).
The esophageal-tracheal combitube (ETC) has also been recommended as a backup device for difficult MV (1, 2, 22), but the user must verify the corrrect lumen through which ventilation is possible. When properly positioned, the ETC protects against gastric fluid regurgitation and allows ventilation with high seal pressures, both special features of this device. Unfortunably, this valuable airway for emergency situations is available only in two sizes for large and normal-sized adults. Laryngeal tubes (LTs) are similar in design to the ETC, also intended for blind esophageal insertion, and are available in different sizes; however, LTs cannot provide ventilation when the tip of the relatively short tube is positioned at the level of the laryngeal aperture or partly in the trachea. The design of this device has been revised several times; the recently released modifications of the LT have now an incorporated esophageal drain tube for gastric drainage. LTs may be also valuable backup devices for difficult MV (4); unfortunably, there are currently only case series available to support this suggestion.
The modified nasal trumpet, simply consisting of a single soft nasopharyngeal airway fitted with a standard TT adapter, is unfortunably an underused rescue ventilation device. In patients with failed MV and tracheal intubation, Beattie (6) demonstrated successful ventilation and oxygenation with this device by manual occlusion of the other nostril and the mouth with one hand by the operator.
The American Society of Anesthesiologists guidelines (1, 2) recommend the use of rigid bronchoscopes as further option for rescue ventilation; we suppose that this technique is less familiar to anesthetists.
Expert working groups also recommend the use of percutaneous transtracheal catheters and percutaneous cricothyrotomy when faced with failed MV and tracheal intubation (2, 11, 31, 42); it appears questionable for us to use less familiar invasive techniques with high serious complication rates (22) in rare emergency situations until we have more data on their performance. The implementation of a comprehensive difficult airway program, as recently demonstrated by Berkow and co-workers (8), may effectively reduce the need for emergency surgical airway access. Anesthetists are now familiar with the various LMAs; therefore it seems reasonable for us that LMAs should replace invasive techniques as primary option.
Recommendations of the Austrian Working Group for Airway Management
The two-person approach may be successful when difficulties with single-person MV are encountered; in this situation, the administration of a NMBD should be considered as neuromuscular blockade may make MV easier, particularly when caused by functional upper airway obstruction. In difficult MV situations, a single CL and tracheal intubation attempt may be an option before initiating backup ventilation strategies. We highly recommend the early use of the classic LMA, the intubating LMA, or preferably the use of the ProSeal LMA as backup and rescue devices for difficult MV, with the ETC at hand as further backup device when the LMA fails. The invasive access to the airway should be reserved only for extremely rare and desperate failed ventilation and tracheal intubation situations.
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