It is a common misconception that a pulse means breathing. However, it is possible for someone to have a beating heart yet not be breathing. This situation, known as respiratory arrest, occurs when the respiratory system fails to adequately exchange oxygen and carbon dioxide, even though the circulatory system continues to function. Understanding this distinction is important for recognizing emergencies and providing appropriate initial care.
Separating Breathing and Circulation
The human body relies on two interconnected, yet distinct, systems for life: the respiratory and circulatory systems. The respiratory system, involving the lungs, is responsible for the intake of oxygen and the expulsion of carbon dioxide, a waste product. Air enters the airways and travels into tiny air sacs called alveoli, where gas exchange occurs, transferring oxygen and carbon dioxide.
The circulatory system, composed of the heart and blood vessels, transports blood throughout the body. It delivers oxygen and nutrients to tissues and organs while collecting carbon dioxide and other waste products. While these systems work in tandem, their mechanics and control centers for breathing and circulation are separate. This physiological independence allows the heart to continue pumping blood for a period after breathing has ceased, as long as some oxygen remains in the blood.
Medical Scenarios Where This Occurs
Several medical situations can lead to a person having a pulse but not breathing, each with its own underlying mechanism. Opioid overdose is a prominent cause, where opioids depress the brain’s respiratory drive by acting on specific centers in the brainstem. This disrupts the signals that control breathing, leading to shallow or absent breaths, while the heart may continue to beat.
Severe head trauma can also result in respiratory arrest. Injuries to the brainstem, which houses the involuntary respiratory control centers, can impair the brain’s ability to regulate breathing patterns. Depending on the extent and location of the injury, this can lead to irregular breathing or complete cessation of breathing, even if the heart’s pumping function remains intact. Similarly, a stroke, particularly one affecting the brainstem, can damage these respiratory control centers, leading to significant breathing problems or respiratory failure.
In cases of choking or severe airway obstruction, breathing is physically blocked. Air cannot enter the lungs, leading to a lack of oxygen. Initially, the heart may continue to pump, but without oxygen, this state cannot be maintained indefinitely. Near drowning incidents also present this scenario, where respiratory impairment from submersion in liquid leads to hypoxemia. The individual stops breathing, but their heart may continue to beat for some time before succumbing to oxygen deprivation.
What to Do in an Emergency
Encountering someone who has a pulse but is not breathing requires immediate action. First, call for emergency medical services (e.g., 911 or your local emergency number). While waiting for help to arrive, assess the person’s condition by checking for responsiveness, observing if their chest rises and falls, and listening for breaths. Simultaneously, check for a pulse, typically at the carotid artery in the neck, for no more than 10 seconds.
If a pulse is clearly present but the person is not breathing, the immediate focus is to provide rescue breaths. To do this, open the person’s airway using the head-tilt, chin-lift maneuver. Pinch their nostrils shut, seal your mouth over theirs, and deliver a breath lasting about one second, watching for their chest to visibly rise. For adults, provide one rescue breath every five to six seconds.
If a strong pulse is present, chest compressions, which are part of cardiopulmonary resuscitation (CPR), are generally not indicated. CPR is performed when there is no pulse and no breathing, combining chest compressions to circulate blood with rescue breaths to provide oxygen. If a pulse is present, the primary issue is lack of oxygen, and rescue breathing directly addresses this. Rapid intervention to restore oxygen flow is important to prevent brain damage, which can occur within minutes without adequate oxygen supply.