CPR is done in virtually every case with compressions only. CPR with breaths interspersed with compressions is now all but abandoned. Compression only CPR started during the beginning of the AIDS epidemic. At that time people became unwilling to do breaths with compressions and there became a need for evidence for CPR with compressions only. The scientific method requires an open mind when investigating a question but in this case a conclusion was necessary to support what had to be done. There is evidence but the evidence is biased for compressions only CPR forced by circumstances.
Compressions only CPR might make sense in primary V-fib. In such cases we could expect the blood to be reasonably oxygenated and therefor the limited circulation of blood provided by compression only could be beneficial. The current reality of guidelines is that this consideration is ignored. The cause of the cardiac arrest is not considered.
In cases of near drowning we would expect that cardiac arrest would occur after profound deoxygenation of the blood. Circulating deoxygenated blood with compressions only CPR would not be helpful. Ventilation of the lungs after near drowning would be essential. It is likely that rescue breathing rather than compressions at all would be the best approach. Cardiac arrest in the field is the absence of a pulse usually by an untrained and inexperienced rescuer, the bystander. This does not mean that the heart is not beating only that the force of contraction does not produce a pulse that can be felt. In near drowning, we know that the primary process involves breathing and the lack of oxygen. Rescue breathing makes sense. Anything that interferes with the delivery of effective rescue breathing is likely detrimental. It is tragic that simple rescue breathing is no longer employed in near drowning, costing many lives.