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First Aid

Concern about rescue breathing

From Dr H. T. Dougall, MRPharmS, MRCGP

May I firstly commend The Journal for commissioning, and Dr Newman for writing, the recent series of articles on first aid. This is clearly an important area that pharmacists come into contact with on a daily basis. I would wish to clarify a couple of points, however. The sequence of events undertaken in Basic Life Support (BLS) is often confused and disorganised because of the atmosphere of panic that often descends when someone has collapsed or suffered a cardiac arrest. The simpler the protocol the better.

Once dangers to oneself have been excluded, a rescuer approaches a patient and attempts to see if he or she is responsive. If not — shout for help.

A. Check then open the airway (head tilt/chin lift).

B. Check the breathing: if not breathing start mouth-to-mouth ventilation (adults, 10 breaths per minute; infant/ baby, 20 per minute)

C. Check the circulation: if no signs of circulation start chest compressions (100 per minute)

The point at which a rescuer leaves a casualty to phone for help during the process reflects the likely aetiology of the event. If the casualty is an adult, a cardiac cause is most common. The collapse is likely due to an arrhythmia, eg, ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT). Once cardiac output ceases cerebral hypoxia injury starts within three minutes. Attempted defibrillation is the single most important therapy for the treatment of VF/VT. The time interval between the onset of VF/VT and the delivery of the first shock is the main determinant of patient survival. Survival falls by approximately 7 to 10 per cent for each minute after collapse. Therefore, after assessing the airway, a rescuer should immediately leave the casualty (if no one else is there to help) and summon help (ie, a defibrillator) by telephoning 999. In children, trauma, drowning, or where there is drug or alcohol intoxication, unconsciousness is normally secondary to hypoxia. Therefore the protocol differs in that one minute of CPR is administered in an attempt to deliver oxygen before going for definitive assistance.

The “gold standard” sign of cardiac arrest is an absent carotid (or other large artery) pulse. It has been shown, however, that assessment of the carotid pulse is time consuming and leads to incorrect conclusion (present or absent) in up to 50 per cent of cases. In those who are not health care professionals, confident and trained in assessing pulses, after checking and opening the airway, circulation is assessed not by carotid pulse, but by looking, listening and feeling for normal breathing, coughing or movement by the casualty. If none of these signs is present, or one is all unsure, the Resuscitation Council (UK) now recommends starting chest compressions.

Finally, despite the relative safety of mouth-to-mouth rescue breathing, it is clear that there is significant reluctance to perform this on unknown victims. There is good evidence now that chest compression without mouth-to-mouth ventilation is significantly better than no CPR at all. Thus, if a person is unwilling, or unable, to perform mouth-to-mouth ventilation for an adult in cardiac arrest, chest-compression-only CPR should be provided. If this can be combined with head tilt to provide a patent airway, chest compressions alone might produce some ventilation of the victim's lungs.

Hamish T. Dougall
Tayside Centre for General Practice
Dundee

Dr LOTTE NEWMAN (medical adviser, St John Ambulance) replies:

With regard to the final paragraph of this letter, it is accepted that the risk of acquiring infection while performing mouth-to-mouth rescue breathing is very low. However, reluctance to perform this on an unknown victim is understandable. As Dr Dougall states, chest compressions alone are better that no CPR at all, but the purpose of the treatment is to improve the oxygen supply to the vital organs and the brain in particular. No oxygen entering the lungs will mean an ever-falling oxygen tension in the blood circulated by chest compression, so that, in anything but the short term, rescue breathing is an essential component of resuscitation. For those who are reluctant on aesthetic grounds to perform rescue breathing, a face shield with a non-return valve or a pocket mask provide acceptable alternatives. Perhaps this is an item which might be stocked and promoted by pharmacists with a view to encouraging public awareness of life support procedures.

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