Chapter 6. Basic management of the airway and ventilation
• Airway management is the cornerstone of emergency care
• Airway obstruction producing hypoxia will lead to circulatory arrest and irreversible central nervous system damage within 3–4 minutes
• Often the application of basic skills is all that is required.
Simple airway management
Upper airway patency can generally be re-established by correctly positioning the head and by use of the head tilt, the chin lift or if the cervical spine may be damaged, the jaw thrust. Simple adjuncts may further improve the situation.
Foreign body airway obstruction
• The algorithm for the management of choking in the adult is on p. 37. In patients who are (or become) unconscious due to airway destruction, tilt the head back and remove any visible foreign object. Perform a chin lift and check for breathing: if this is absent, begin CPR with chest compressions and continue until ALS equipment (laryngoscope, Magill’s forceps, and cricothyroidotomy kit) is available. Ideally the suction end should be manipulated under direct vision using a laryngoscope
• A flexible catheter can be used to clear the lumen of an airway adjunct, such as a nasopharyngeal airway, tracheal tube or laryngeal mask.
Liquid in the airway
• The best way of removing liquid from the oropharynx is by direct suction using a wide-bore or Yankauer suction catheter
• Suction should only be performed under direct vision. ‘Blind’ suctioning may lead to airway injuries or oedema
• Adult suction devices must not be used on neonates. Specialist suction devices (soft tipped, dual chamber) should be used.
Respiratory control
Central control
The brainstem controls respiration. Sleep, sedatives, alcohol, many analgesic drugs and injury to the respiratory centres result in hypoventilation. This reduction in ventilation may result from a fall in respiratory rate or tidal volume or both. Ventilation is stimulated by a rise in arterial carbon dioxide or a fall in arterial oxygen and is also stimulated by a fall in blood pH which may occur, e.g. in a hyperglycaemic diabetic coma.
Chronic obstructive pulmonary disease
Patients with chronic obstructive pulmonary disease tend to have high levels of carbon dioxide in their blood. Some of these patients will have adapted to these high levels and their stimulus to breathing will be provided only by low oxygen levels rather than by increases in carbon dioxide.
Thus, if high inspired concentrations of oxygen are given to these patients they may lose their respiratory drive leading to carbon dioxide retention and decreasing consciousness. It is important to remember that a high carbon dioxide content kills slowly, but a low oxygen content kills quickly. Thus the need to provide immediate adequate oxygenation takes precedence. Hence cyanotic patients should always be treated with high oxygen concentrations.
Peripheral control
• Adequate ventilation also requires an intact chest wall and intrapulmonary mechanics
• Peripheral causes of impaired ventilation include obstruction of the upper airway, most commonly due to the tongue
• The phrenic nerves originate from cervical spinal roots C3–5; therefore diaphragmatic function will be maintained with cord lesions below this level.
Airway and ventilation assessment
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