Airway Establishment and Control
Airway management consists of
There are many indications for airway control (see Table: Situations Requiring Airway Control) and many methods of establishing an airway, including
Whatever airway management techniques are used, tidal volume should be 6 to 8 mL/kg (significantly less than previously recommended) and ventilatory rate should be 8 to 10 breaths/min (significantly slower than previously recommended to avoid negative hemodynamic consequences). Slower rates are commonly used in patients with severe air trapping (eg, acute asthma, COPD), and passive oxygenation without positive pressure ventilation shows promise in the first minutes after cardiac arrest. Smaller volumes and slower respiratory rates are also desirable in any state of hemodynamic instability; however, it is important to keep in mind that positive pressure ventilation is the opposite of physiologically normal negative pressure ventilation. In cardiac arrest, physiologic demands are significantly less, and in non-arrest, the benefits of hypoventilation in hemodynamic stability and lung protection often outweigh the negative effects of permissive hypercapnia and moderate hypoxia.
Situations Requiring Airway Control
To relieve airway obstruction caused by soft tissues of the upper airway and provide optimal position for bag-valve-mask ventilation and laryngoscopy, the operator flexes the patient’s neck to elevate the head until the external auditory meatus is in the same plane as the sternum and positions the face roughly parallel to the ceiling (see Figure: Head and neck positioning to open the airway.). This position is slightly different from the previously taught head tilt position. The mandible should be displaced upward by lifting the lower jaw and submandibular soft tissue or by pushing the rami of the mandible upward (see Figure: Jaw lift.).
Head and neck positioning to open the airway.
Anatomic restriction, various abnormalities, or considerations caused by trauma (eg, inadvisability of moving a possibly fractured neck) may obviate the operator’s ability to properly position the neck, but careful attention to optimal positioning when possible can maximize airway patency and improve bag-valve-mask ventilation and laryngoscopy.
Obstruction by dentures and oropharyngeal foreign material (eg, blood, secretions) may be removed by finger sweep of the oropharynx and suction, taking care not to push the material deeper (more likely in infants and young children, in whom a blind finger sweep is contraindicated). Deeper material can be removed with Magill forceps or by suction.
The Heimlich maneuver (for more detailed instructions, see How to do the Heimlich Maneuver) consists of manual thrusts to the upper abdomen or, in the case of pregnant or extremely obese patients, chest thrusts until the airway is clear or the patient becomes unconscious; it is the preferred initial method in the awake, choking patient.
In conscious adults, the rescuer stands behind the patient with arms encircling the patient’s midsection. One fist is clenched and placed midway between the umbilicus and xiphoid. The other hand grabs the fist, and a firm inward and upward thrust is delivered by pulling with both arms (see Figure: Abdominal thrusts with victim standing or sitting (conscious).).
An unconscious adult with an upper airway obstruction is initially managed with CPR. In such patients, chest compressions increase intrathoracic pressure in the same manner that abdominal thrusts do in conscious patients. Rescuers should examine the oropharynx before each set of breaths and use their fingers to remove any visible objects. Direct laryngoscopy with suction or Magill forceps can also be used to remove a foreign body in the proximal airway, but once an object has passed through the vocal cords positive pressure from below the obstruction is most likely to be successful.
In older children, the Heimlich maneuver may be used. However, in children < 20 kg (typically < 5 yr), very moderate pressure should be applied, and the rescuer should kneel at the child’s feet rather than astride.
In infants< 1 yr, the Heimlich maneuver should not be done. Infants should be held in a prone, head-down position. The rescuer should support the head with the fingers of one hand while delivering 5 back blows (see Figure: Back blows—infant.). Five chest thrusts should then be delivered with the infant in a head-down position with the infant’s back on the rescuer’s thigh (supine—see Figure: Chest thrusts—infant.). This sequence of back blows and chest thrusts is repeated until the airway is cleared.