RSV is a common seasonal virus affecting the lungs and respiratory tract. While often a mild cold in older children and adults, it can cause serious lower respiratory tract infection in infants, especially those under six months. RSV is the leading cause of hospitalization for infants under one year old. Caregivers should monitor breathing sounds and recognize signs of respiratory effort to determine when medical attention is required.
Identifying the Key RSV Breathing Sounds
The most commonly recognized sound associated with a serious RSV infection is wheezing, a high-pitched whistling or musical sound. This sound occurs when air attempts to rush through narrowed or obstructed airways. Caregivers typically hear this whistling sound most clearly when the child is exhaling.
Another distinct sound heard in the lungs during a severe RSV infection is crackles, or rales. These sounds are often described as wet, bubbling, or popping noises, sometimes compared to the sound of “Rice Krispies” in the chest. Crackles are caused by the reopening of small, collapsed airways or by air bubbling through secretions and fluid.
Beyond these specific sounds, a child with RSV may exhibit general noisy or rapid breathing, medically termed tachypnea. The breathing may sound raspy or coarse due to mucus buildup in the upper airways. Rapid breathing is a sign of distress, as the body attempts to compensate for poor oxygen exchange by taking many short, shallow breaths.
The Impact of RSV on Airways
The characteristic breathing sounds of RSV arise because the virus attacks the lower respiratory tract, leading to bronchiolitis. This infection causes inflammation and swelling specifically in the bronchioles, the smallest air passages in the lungs. The virus targets the epithelial cells lining these airways, causing them to become damaged.
Cellular damage and the body’s inflammatory response lead to the production of thick, sticky mucus. The combination of swollen airway walls and plugs of mucus creates a significant blockage in the tiny bronchioles. Since these small airways are already narrow in infants, even minor swelling causes substantial obstruction, making it difficult for air to pass.
This partial obstruction is most pronounced when the child exhales, as airways naturally narrow during this phase. Air is forced through this constricted space, generating the high-pitched wheezing sound. Airflow restriction can also lead to air trapping, where air gets stuck in the lungs, increasing the effort required for the child to breathe.
Visual Signs of Severe Respiratory Distress
Caregivers must look for visual cues that indicate a child is struggling to breathe. One primary sign is the presence of retractions, which occur when the chest wall visibly sinks in with each breath. These retractions can appear between the ribs (intercostal), below the rib cage (subcostal), or at the base of the neck/above the collarbone (suprasternal).
This visible tugging shows the child is using accessory muscles—muscles not normally used for quiet breathing—in an intense effort to pull air into the lungs. Another visual sign of increased respiratory effort is nasal flaring, where the nostrils widen with every inhalation. This action is an instinctive attempt to reduce airway resistance and maximize the amount of air entering the lungs.
In severe cases, a child may exhibit cyanosis, a bluish or grayish discoloration of the skin, lips, or nail beds. Cyanosis signals that the body is not getting enough oxygen and requires immediate emergency intervention. The child may also appear unusually tired or lethargic, or they may be irritable and have difficulty feeding because they are exerting too much energy on breathing.
When to Contact a Healthcare Provider
A child exhibiting visual signs of respiratory distress, such as retractions, nasal flaring, or cyanosis, requires immediate emergency medical attention. Call emergency services immediately if a child’s breathing pauses for more than a few seconds (apnea), or if they are unresponsive and extremely lethargic. These signs indicate a life-threatening lack of oxygen.
Less acute symptoms still warrant an urgent call to a healthcare provider or a visit to an urgent care facility. Seek medical advice if the child is unable to drink liquids or breastfeed, leading to signs of dehydration (e.g., significantly fewer wet diapers over an eight-hour period). A persistent fever, especially in an infant under 12 weeks old, should also prompt a call.
Caregivers should seek medical consultation if wheezing or coughing worsens significantly, or if the child is a high-risk patient due to prematurity or a pre-existing heart or lung condition. RSV symptoms typically peak between days three and five of the infection, so timely action is essential to catch the progression of the illness early.