This is achieved by placing one hand on the pa tient's forehead and shaking his or her shoulders gently with the other hand, whilst at the same time asking loudly 'Are you all right?'
The head is held stable during the assessment to guard against the possibility of aggravating an injury to the cervical spine.
Always assume the victim may be deaf; therefore ensure that he or she can see your lips move when assessing responsiveness.
In most unconscious victims the airway will become obstructed at the level of the hypopharynx, as the reduced tone in muscles of the tongue, jaw and neck allows the tongue to fall against the posterior pharyngeal wall (Fig. 4.1). Correction, using the following techniques, may allow recovery without the need for further intervention.
• Head tilt plus chin lift (Fig. 4.2) The rescuer's hand nearest the head is placed on the forehead, gently extending the head backwards. The chin is then lifted using the index and middle fingers of the rescuer's other hand. If the mouth closes, the lower lip should be retracted downwards by the thumb.
• Jaw thrust(Fig. 4.3) This is used if the above technique fails to create an airway, or there is a suspicion that the cervical spine may have been injured. The patient's jaw is 'thrust' upwards (forwards) by the rescuer applying pressure behind the angles of the mandible.
• Finger sweep The mouth must be opened and inspected, and any obvious material contributing to the obstruction removed by placing a finger in the mouth and gently sweeping from side to back, 'hooking' out loose material. At the same time, broken, loose or partial dentures should be removed, but well-fitting ones may be left in place (see later).
Checking for evidence of breathing. Maintain an airway using one of the above techniques, then (Fig. 4.4):
• Look: down the line of the chest to see if it is rising and falling.
• Listen: at the mouth and nose for breath sound, gurgling or snoring sounds.
• Feel: for expired air at the victim's mouth and nose with the side of one's cheek.
If there is no evidence of spontaneous ventilation, expired-air ventilation will be required.
Expired-air ventilation (rescue breathing or mouth-to-mouth ventilation)
• There must be a clear path, with no leaks, between the rescuer's lungs and the victim's lungs.
• Keep the victim's airway patent by performing a head tilt, while using the index finger and thumb
of the same hand to pinch the nose to prevent leaks.
• The fingers of the lower hand are then used to perform a chin lift, and if necessary open the victim's mouth (Fig. 4.5a).
• The rescuer takes a deep breath in and makes a seal with their lips around the victim's mouth.
Well-fitting dentures are often usefully left in situ as they help maintain the contour of the mouth and make it easier to create a good seal.
• The rescuer then breathes out into the victim's mouth for 1.5-2s.
• At the same time look down the victim's chest: each breath should be sufficient to make the chest rise clearly (Fig. 4.5b).
• Maintaining the head tilt/chin lift, the rescuer now moves away from the mouth to allow passive exhalation for 2-4 s, watching to ensure the chest falls (Fig. 4.5c).
Each complete cycle of expired-air ventilation should take 5-6 s, thereby allowing 10-12 breaths/min.
This technique is used where mouth-to-mouth ventilation is unsuccessful, for example if an obstruction in the mouth cannot be relieved, or when the rescuer is a child.
• The airway is maintained with a head tilt, but the mouth is closed with the fingers of the lower hand.
• The seal is made by the rescuer's lips around the base of the victim's nose.
• Inspiration is as above, checking to ensure that the chest rises.
• The victim's mouth is opened to assist with expiration, the rescuer watching to ensure that the chest falls.
Common causes of inadequate ventilation
• Obstruction: failing to maintain head tilt, chin lift.
• Leaks: inadequate seal around the mouth or failure to occlude the patient's nose.
• Exhaling too hard: trying to overcome an obstructed airway, resulting in gastric distension.
• Foreign body: unrecognized in the patient's airway.
Check for evidence of a circulation:
• Look, listen and feel for normal breathing, coughing or movement by the victim.
• If you are trained, check for the presence of a pulse:
• Central arteries are more reliable than peripheral ones as a pulse will be palpable even with a very low cardiac output.
• The carotid artery is usually the most accessible and acceptable.
• If there is no evidence of a spontaneous circulation, then chest compressions will be required.
This technique only results in a maximum cardiac output 30% of normal, and in order to achieve this the position of the hands is critical:
• The rescuer positions him/herself on one side of the victim.
• The victim's chest is exposed and the xiphister-num identified.
• The index and middle fingers of the rescuer's lower hand are placed on the xiphisternum and the heel of the other hand is placed adjacent to them on the sternum (Fig. 4.6a).
• The fingers are then removed and the heel of the second hand placed on the back of the hand on the sternum. The fingers may then be interlocked.
• The sternum is depressed vertically 4-5 cm and then released rapidly.
• This is repeated at a rate of approximately 100/min, compression and relaxation each taking the same length of time.
To optimize compression and reduce rescuer fatigue chest compressions are best performed with the rescuer leaning well forward over the patient, arms straight and hands, elbows and shoulders extended in a straight line. This allows use of the rescuer's upper body weight to achieve compression, rather than the arm muscles, which will rapidly tire and reduce efficiency (Fig. 4.6b).
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