For patients with acute respiratory failure or arrest, airway and ventilation adjuncts are useful to maintain an airway that would otherwise require continuous bag-valve-mask (BVM) ventilation. In addition, some airway adjuncts aid in preventing gastric distention or aspiration ( Fig 2-2).
FIG. 2-2. Airway devices and adjuncts. A. Combitude. B. Pharyngeal tracheal lumen airway. C. Nasopharyngeal airway. D. Oropharyngeal airway. E. Tube exchanger. F. Laryngoscope. G. Magill forceps. H. Qualitative end expiratory CO 2 detector. I and J. Stylets for endotracheal intubation. K. Endotracheal tube.
The simplest devices for airway management used with BVM ventilation are the oropharyngeal and nasopharyngeal airways. These devices prevent obstruction of the upper airway so that externally applied positive-pressure ventilation can reach the trachea. Effective portable suction devices are available that can be carried to the patient's side to help clear the airway (Fig 2-3).
FIG. 2-3. Suction devices. A. Yankauer rigid suction catheter. B. V-Vac (Laerdal Medical Corp., Wappingers Falls, NY) portable suction device. C Flexible suction
More advanced airway devices are required if the patient needs more prolonged airway management or is at risk for aspiration. At the BLS level, available options include the pharyngeal tracheal lumen (PTL) airway, the esophagotracheal double lumen tube (or, simply, Combitube), and the laryngeal mask airway (LMA). Each of these is used in conjunction with a bag-valve for ventilation. These devices are great improvement over the old esophageal obturator airway and esophageal gastric airway, both of which had unacceptably high complication rates and are no longer recommended for use. Both the PTL and the Combitube (Sheridan Corp.) are only for adult patients in full cardiac arrest. The PTL and Combitube provide a seal in the upper airway—to promote better ventilation than the BVM with oral airway—and a seal in the esophagus—to prevent gastric regurgitation and aspiration. Both devices are passed blindly, and the tube usually passes into the esophagus. A small percentage of the time, the device goes into the trachea, where it can function as an endotracheal tube. There is some evidence that the Combitube is an easier device to use than the PTL because the large PTL mouth balloon is more easily broken than the Combitube balloon. 6 The Combitube may be easier for basic emergency medical technicians (EMTs) to ventilate through. There are few data on usage of the LMA for out-of-hospital care. While the lMa provides a seal for ventilation, it does not prevent aspiration. One possible advantage of the LMA is that it is less expensive than the Combitube or the PTL. The PTL and/or Combitube is mostly used by BLS ambulance personnel but may be used by ALS personnel (or even by hospital personnel) for a patient with a difficult airway who cannot be intubated with an endotracheal tube. The disadvantages of the PTL, Combitube, or LMA is that it cannot be used in small adults, children, or patients who are somewhat responsive with a gag reflex.
Endotracheal intubation is the "gold standard" for airway management; it provides the best access for ventilation and the greatest protection against aspiration. The majority of ALS systems use endotracheal intubation as the airway of choice for the patient in respiratory failure or with an unprotected airway. Therefore, a number of different-sized endotracheal tubes, laryngoscope blades with handles, stylets, lubricants, and Magill forceps must be carried in the airway kit. Tube exchanger catheters or gum bougies can also aid with establishing a difficult endotracheal tube. Directors of EMS must ensure that ALS personnel maintain their intubation skills through field experience and practice.
The new basic EMT model curriculum has made endotracheal intubation an optional module. Therefore, intubation training may be provided to basic EMTs and intubation equipment may be placed on some BLS ambulances. Increasing the number of ambulance personnel in need of endotracheal intubation training in an EMS system may cause logistical problems for the medical director. It is sometimes difficult to obtain adequate live intubation opportunities for the personnel in an EMS system in order to develop and maintain skills. Some studies have found that basic EMTs do not maintain endotracheal intubation skills and have low rates of successful field intubations.78 This would suggest that intubation will generally remain an ALS skill.9
Another intubation-related modality that has bearing on the equipment carried on the ambulance is rapid sequence intubation (RSI) using intravenous (IV) hypnotics and neuromuscular paralytic drugs.10 Critical care transport services have been using RSI for more than a decade, but now a number of ALS systems are doing so, also with good success. The use of RSI raises the level of psychomotor and judgment skills required of the paramedic. While the use of RSI increases the amount of training needed, it enables paramedics to secure more difficult airways. In addition to the usual equipment required for intubation, these ALS services must carry the drugs needed for sedation and paralysis.
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