Periodic breathing is a cyclical pattern of respiration characterized by alternating periods of deep breathing and shallow breathing or pauses. This irregular pattern involves clusters of breaths separated by intervals where little to no airflow occurs. While sometimes a harmless physiological variation, this irregular breathing pattern often signals an underlying instability in the body’s respiratory control system.
The Mechanics of the Cycle
The pattern of periodic breathing is defined by a distinct, repeating physiological cycle. The cycle begins with a phase of hyperpnea, characterized by breathing that is deeper and often faster than usual. This over-breathing reduces the body’s carbon dioxide (\(\text{CO}_2\)) levels, leading to a state of hypocapnia.
The drop in \(\text{CO}_2\) acts on the central chemoreceptors, which are highly sensitive to this gas, causing the respiratory drive to become temporarily inhibited. This inhibition results in a brief period of apnea, or complete cessation of breathing, typically lasting between five and ten seconds. As the pause continues, \(\text{CO}_2\) levels slowly rise again, eventually crossing a threshold that reactivates the respiratory centers in the brainstem. The cycle then restarts with the initial hyperpnea phase, creating a distinctive waxing and waning pattern of air movement.
Periodic Breathing in Newborns
In the first few months of life, periodic breathing is a common and usually normal physiological occurrence, especially in premature infants. This is primarily attributed to the immaturity of the infant’s central nervous system, particularly the respiratory control centers in the brain. The developing system has a less stable control over the balance of oxygen and \(\text{CO}_2\) in the blood, making it prone to the cyclical overshoots and undershoots that define this pattern.
In this context, periodic breathing involves brief pauses in breathing, typically lasting no more than 10 seconds, which are then followed by a series of rapid, shallow breaths. Crucially, these episodes do not cause any significant change in the baby’s heart rate, oxygen saturation, or skin color. The infant will spontaneously resume a normal breathing pattern without any intervention.
It is important to distinguish this normal pattern from true apnea of prematurity. Apnea of prematurity is diagnosed when a breathing pause lasts for 20 seconds or longer, or when a shorter pause is accompanied by bradycardia (a significant drop in heart rate) or cyanosis (a bluish discoloration of the skin). While periodic breathing is harmless and resolves by around six months of age, true apnea is considered a medical issue requiring monitoring and potential treatment.
Contexts Where Adults Experience Periodic Breathing
When periodic breathing is observed in adults, it is often a sign of a significant underlying medical condition or a physiological response to an extreme environment.
Cheyne-Stokes Respiration
One specific and widely recognized form is Cheyne-Stokes respiration, a pattern strongly associated with severe illness. This type is characterized by a gradual increase in breathing depth, followed by a gradual decrease, and then a period of apnea before the pattern repeats, creating a smooth crescendo-decrescendo waveform.
Cheyne-Stokes respiration frequently occurs in patients with congestive heart failure, and is also seen following a stroke. In heart failure, a delay in blood circulation time between the lungs and the brain’s respiratory centers contributes to the instability, causing the body to overreact to changes in blood gas levels. This pattern is a form of central sleep apnea, where the brain fails to send the proper signals to the breathing muscles.
High Altitude and Central Sleep Apnea
Another context where the pattern appears is at high altitudes, known as high-altitude periodic breathing. The low oxygen content triggers an enhanced ventilatory response from peripheral chemoreceptors, leading to hyperventilation and a drop in blood \(\text{CO}_2\). This low \(\text{CO}_2\) level suppresses the drive to breathe during sleep, resulting in repeated cycles of apnea and hyperpnea until the body acclimatizes. Central sleep apnea itself is a condition where the respiratory control system is unstable, meaning the brain does not signal the chest muscles to inhale, often due to a medical disorder or the use of certain medications.
Assessment and When to Seek Help
While periodic breathing in a newborn is generally considered a benign variation of normal, certain signs indicate the need for immediate medical consultation regardless of the individual’s age. Any breathing pause that exceeds 10 to 20 seconds is a warning sign that requires prompt evaluation. A change in skin color, such as a pale or bluish tint around the lips or face (cyanosis), suggests an insufficient oxygen level and warrants urgent attention.
Other signs of respiratory distress include gasping, grunting sounds, or the use of accessory muscles to draw a breath, which can manifest as the chest sinking in or the nostrils flaring. For infants, feeding difficulties, lethargy, or being unusually difficult to wake are also concerning symptoms. Medical professionals typically assess this condition using a polysomnography (sleep study), which monitors brain activity, heart rate, oxygen levels, and breathing effort during sleep.