This is much less common and is an extremely worrying sign. Injured or unwell players who begin to breathe very slowly or not in a regular pattern may be about to stop breathing altogether and may already be in cardiac arrest.
Recognition of cardiac arrest is a key skill and fundamental part of the course and will be covered in detail in another section. However, at this stage, it is important to realise that current guidelines suggest that casualties who are not breathing normally, such as slow irregular (known as agonal) breathing should be regarded as in cardiac arrest and cardiopulmonary resuscitation begun as the absolute priority. How to help someone who is not breathing is covered in the cardiac arrest chapter.