A deviated septum is a common structural condition that affects breathing, leading many people to wonder if this physical obstruction can result in low blood oxygen levels. The nasal septum is a thin wall of cartilage and bone that divides the nasal cavity into two distinct passages. When significantly misaligned, or “deviated,” this structure restricts airflow, causing difficulty breathing through the nose. This article explores the physiological relationship between a deviated septum and oxygen saturation, differentiating between daytime effects and nocturnal complications.
Understanding the Nasal Septum and Obstruction
The nasal septum extends from the base of the skull to the nasal floor, forming the central partition of the nose. The front section is mostly flexible cartilage, while the back portion is bone. A deviation occurs when this wall is displaced to one side, making one nasal passage notably smaller than the other. This misalignment is common, with estimates suggesting that up to 80% of individuals have some degree of septal deviation, though not all experience symptoms.
A deviated septum can be present from birth due to developmental factors or pressure during the birthing process. However, a more frequent cause is trauma, such as an injury to the nose from sports or an accident, which forces the cartilage or bone out of alignment. When the deviation is severe, it physically blocks the passage. Symptoms include chronic congestion, frequent nosebleeds, and difficulty breathing through the nose, which increases airflow resistance.
Airflow Restriction and Systemic Oxygen Levels
The primary function of the lungs is to efficiently transfer inhaled oxygen into the bloodstream to maintain systemic oxygen saturation (\(\text{SpO}_2\)), which is measured at 95% or higher. A deviated septum restricts the initial entry of air into the nasal passages, increasing upper airway resistance. However, the human respiratory system has substantial compensatory mechanisms designed to prevent a drop in blood oxygen levels during waking hours.
When nasal breathing is restricted, the body instinctively switches to mouth breathing to ensure a sufficient volume of air reaches the lungs. Because the lungs are vast and highly efficient, restricted airflow through the nose alone is not enough to cause chronic or clinically significant low oxygen levels. Hypoxia, or abnormally low oxygen saturation, during the day is rarely a direct consequence of an isolated deviated septum in an otherwise healthy individual.
A deviated septum may cause the sensation of not getting enough air, especially during physical exertion. This feeling is due to the increased effort of breathing against resistance, not actual systemic oxygen deprivation. Studies show that even a complete temporary nasal blockage causes only a minor, temporary dip in \(\text{SpO}_2\) in healthy patients. Therefore, a deviated septum alone is not considered a direct cause of chronic daytime low oxygen levels.
The Connection to Sleep-Related Breathing Disorders
The relationship between a deviated septum and low oxygen saturation becomes more pronounced during sleep. When a person is awake, upper airway muscles maintain tone, keeping the passage open despite nasal obstruction. During sleep, these muscles relax, making the pharyngeal airway more susceptible to collapse.
Nasal obstruction from a deviated septum promotes mouth breathing at night, which changes the pressure dynamics in the throat. This increased nasal resistance contributes to or worsens Obstructive Sleep Apnea (OSA). OSA is a condition where the airway repeatedly collapses, leading to pauses in breathing and recurrent events known as apneas and hypopneas.
These recurrent events cause intermittent drops in systemic oxygen levels, resulting in nocturnal hypoxia. While a deviated septum is rarely the sole cause of OSA, it contributes to the severity of the disorder. Correcting the structural issue has been shown to improve the lowest nocturnal oxygen saturation in some patients, highlighting the role of nasal patency.
Corrective Measures for Improved Nasal Airflow
Interventions for a deviated septum aim to reduce nasal airflow resistance and alleviate associated symptoms. Non-surgical management involves the use of nasal sprays, decongestants, or adhesive nasal strips to temporarily open the nasal passages. These measures address symptoms like congestion and swelling but do not correct the underlying structural misalignment.
For a severe deviation causing persistent symptoms, the definitive treatment is Septoplasty. This surgical procedure is performed entirely through the nostrils, avoiding external scarring. The surgeon lifts the mucous membrane to access the cartilage and bone, then straightens, repositions, or removes the deviated portions to restore a centered position and maximize airflow.
The goal of Septoplasty is to improve nasal breathing and enhance quality of life. While not a direct cure for complex conditions like OSA, improved nasal airflow can make treatments, such as Continuous Positive Airway Pressure (CPAP) therapy, more effective and tolerable. Initial recovery takes about one week, though complete internal healing may take several months.