Decision-Making in Emergency Situations
In emergencies with severely compromised patients, the strategies for airway management (AM) require individual decision-making for airway control which may, at times, be at least partially contrary to safe standard patient care. Tracheal intubation by direct or indirect laryngoscopy may be performed following inhalational or intravenous induction of general anesthesia (GA) with or without the use of muscle relaxants. Emergency flexible-bronchoscopy assisted (FBA) tracheal intubation should be attempted only by an experienced operator and abandoned after a limited period of time.
In patients with a difficult airway, inhalational induction of GA is generally considered as the technique of choice because spontaneous respiration can be preserved. In this context, sevoflurane is the anesthetic of choice because it is the least less irritant to the airway of all inhalational anesthetics, and it has a rapid onset of action and is rapidly eliminated. However, we emphasize that upper airway obstruction problems may develop during inhalational induction from collapse due to the decrease in pharyngeal muscle tone. Furthermore, airway interventions during light planes of inhalational anesthesia may provoke additional functional upper airway obstruction.
Intravenous induction of GA with the use of a non-depolarizing neuromuscular blocking drug with rapid onset of action as provided by rocuronium may facilitate face-mask ventilation (MV) and improve conditions for tracheal intubation. When MV and two-person, two-handed MV prove difficult or even impossible and maximally two tracheal intubation attempts fail after induction of GA, expert working groups generally favor the use of laryngeal mask airways (LMAs) for rescue ventilation before initiating an invasive transtracheal access to the airway (2, 13, 20).
In patients with compromised upper airway patency, the use of the ProSeal laryngeal mask airway (PLMA) should be considered because it forms a better seal and allows higher insufflation pressures than other LMAs. Although we favor LMAs as reasonable backup devices (23), we need to emphasize that the few published case series on the use of LMAs in patients with upper airway obstruction report conflicting results on their performance (5, 8). Ventilation with low positive end-expiratory pressure applied through a LMA positioned close to the larynx may splint open the narrowed airway. In patients with already restricted pharyngeal space, insertion of a LMA may be difficult and in those with increasing upper airway distortion, alignment of the LMA with the larynx may be impossible.
When successfully inserted, LMAs may be used as conduit for tracheal intubation, preferably performed under guidance of a flexible bronchoscope. There is evidence that for this definitive approach to the airway, intubating LMAs may perform best (10, 13, 15). Cook and co-workers (7, 8) prefer the PLMA and the two-stage FBA technique using an Aintree intubating catheter (AIC) for guidance of the tracheal tube (TT) into the trachea. This technique may be successfully performed also by less experienced operators (14).
The various models of the laryngeal tube (LT), mainly used in prehospital AM, may be considered as additional alternative devices for rescue ventilation (4). They are similar in design to the esophageal-tracheal combitube, available in different sizes, and also intended for blind esophageal insertion. When properly positioned, LTs allow ventilation with favorable sealing properties and FBA tracheal intubation with an AIC.
The modified nasal trumpet, consisting of a soft nasopharyngeal airway fitted with a TT adapter, is unfortunately an underused rescue ventilation device. During failed MV and tracheal intubation, oxygenation and ventilation can be maintained through the nasopharyngeal airway while the second hand of the operator occludes the other nostril and the mouth (6). Contralateral FBA nasotracheal intubation may subsequently be performed under continued oxygenation and ventilation.
The American Society of Anesthesiologists guidelines (1, 2) recommend the use of rigid bronchoscopes as further option for rescue ventilation. When inserted into the trachea, they also allow tracheal intubation using an airway exchange catheter. We assume that this technique is less familiar to anesthetists and is regularly practiced by only few laryngologists, pulmologists, and thoracic surgeons.
When attempts at oxygenation and ventilation fail, immediate surgical cricothyrotomy or tracheotomy must be initiated. In these situations, percutaneous techniques for transtracheal airway access may not be feasible or associated with high serious complication rates.
Webmaster: Ernst Zadrobilek, MD.
Email address: email@example.com