An adequate ratio of high quality chest compressions and rescue breaths are crucial. The recommended rate for CPR is 100 chest compressions per minute. Thereafter a continual sequence of 2 breaths and 30 chest compressions is recommended. Mechanical chest compression devices have not been found to be better than standard manual compressions. For diagnosis of rhythm, AEDs often require the stopping of chest compressions and rescue breathing. In children, giving oxygen, supporting their breathing, and chest compressions are recommended. The investment cost $1.8M and increased participants' understanding of the purpose of compressions during CPR. The intermittent compressions of the sleeves will ensure the movement of venous blood. Both children and adults should receive a hundred chest compressions per minute. It is well documented that quality chest compressions with minimal interruption result in improved survival. A sequence of back slaps and chest compressions are used instead. Interposed abdominal compressions may be beneficial in the hospital environment. Several published evaluations show that these devices can improve the performance of chest compressions. A sound wave propagating underwater consists of alternating compressions and rarefactions of the water. Some units can also give timing reminders for performing compressions, ventilating and changing operators.