When a person collapses from sudden cardiac arrest, immediate cardiopulmonary resuscitation (CPR) by a bystander offers the greatest chance of survival. This bystander action bridges the time gap until professional help arrives, which can often be several minutes. The moment trained Emergency Medical Services (EMS) personnel enter the scene marks a significant transition from layperson care to advanced resuscitation efforts. This shift introduces a brief, high-stakes period where the quality of the ongoing chest compressions must be maintained as the team prepares to take over. The question of whether to continue or stop compressions is a matter of protocol and physiology in this high-pressure situation.
The Critical Handover Phase
The direct answer to whether a bystander should continue CPR when EMS arrives is unequivocally yes; compressions must not stop until a member of the EMS team is ready to take over. This is a deliberate process known as the “handover,” governed by the principle of minimizing interruptions to blood flow. As the EMS crew approaches, the bystander should maintain the high-quality compressions they have been performing. They should not pause to greet the team or step away from the patient prematurely.
The bystander’s immediate task is to continue compressions while simultaneously providing a brief verbal report to the EMS leader without breaking rhythm. This report should concisely communicate the time CPR started, the number of compression-to-ventilation cycles performed, and any specific observations, such as the use of an Automated External Defibrillator (AED) or any shocks delivered. This concurrent action ensures the EMS team gains situational awareness and medical history while the patient continues to receive perfusing blood flow. The bystander should only cease compressions when the EMS provider is positioned directly over the patient’s chest and has given an explicit instruction to pause or stop.
The transition involves the EMS team setting up sophisticated monitoring and advanced airway equipment. The EMS crew will often have a plan to perform a coordinated switch to a mechanical device or a new provider, which requires a momentary pause timed by the professionals. This procedure ensures the “hands-off” time is controlled and limited to the absolute minimum necessary to attach a defibrillator or perform a procedure.
Importance of Minimizing Compression Interruptions
Minimizing the interruption of chest compressions is a fundamental tenet of modern resuscitation guidelines, directly linked to patient outcomes. The reason for this strict protocol is physiological, centered on maintaining adequate coronary perfusion pressure (CPP). CPP is the pressure that drives blood into the heart muscle itself. Research has established that a CPP of at least 15 millimeters of mercury (mmHg) is necessary to achieve a return of spontaneous circulation (ROSC).
A pause in chest compressions, even for a short period like 10 seconds, causes a rapid and significant drop in this vital CPP. The pressure generated by compressions is not instantaneous; it takes approximately 45 seconds of continuous, high-quality compressions to build CPP to its maximum effective level. When compressions stop, this pressure is lost almost immediately, and upon resumption, it takes another considerable period to rebuild. Therefore, even a brief interruption in the handover phase effectively resets the heart’s perfusion status to near zero, substantially reducing the chance of a successful resuscitation.
The continuity of compressions is important, and the EMS team plans their advanced interventions, such as intubation or defibrillation, around this principle. For instance, defibrillator pads are often placed while compressions are ongoing, and the pause for the actual shock is kept to under five seconds. The bystander’s role is to maintain this relentless flow until the professional team is fully prepared to continue with their own hands or equipment. This focus on minimizing “hands-off” time is the scientific justification for the handover protocol.
Bystander Role After Transfer of Care
Once the EMS team has fully taken over the resuscitation effort, the bystander’s role shifts from an active rescuer to an information provider and scene supporter. Stepping back a safe distance ensures that the medical professionals have the necessary space to work with their advanced equipment. The rescuer should remain calm and available, as the EMS crew will need a detailed account of the events leading up to the cardiac arrest.
Accurate documentation is a significant part of pre-hospital care, and the bystander’s observations provide invaluable context for the patient’s treatment. Details such as the patient’s initial appearance, the estimated time of collapse, and any medications found nearby can greatly influence the EMS team’s treatment decisions. The bystander should be prepared to answer questions concisely and accurately to assist with this documentation process.
Intervening to perform CPR is a positive act. In many jurisdictions, laws exist to protect laypersons who provide reasonable assistance during an emergency. These Good Samaritan laws shield the rescuer from legal liability for unintended injuries or negative outcomes, provided they acted in good faith and without gross negligence. The bystander’s primary post-handover responsibility is to be a resource for information and to allow the professional team to continue the life-saving work.