However, it has become increasingly clear that health care providers do not always perform high-quality cardiopulmonary resuscitation (CPR). To address this issue, the 2005 American Heart Association Guidelines for CPR and Emergency Cardiovascular Care provides a number of evidence-based recommendations detailing how to deliver effective chest compressions. For example, these guidelines and the evidence stress the importance of providing chest compressions as early as possible after cardiovascular collapse, minimizing interruptions to compressions, and permitting chest-wall recoil. The guidelines also give specific recommendations on how to perform chest compressions on adults, including a rate of 100 compressions per minute, a compression to ventilation ratio of 30:2 for the unintubated patient, and a compression depth of 1.5 to 2 in (4 to 5 cm).