What is Nocturnal Asthma: Symptoms, Causes, Treatment, Pathophysiology, Risk Factors
What is Nocturnal Asthma?
More than 90% of patients suffering from asthma have reported experiencing nighttime wheezing and coughing, which often aggravates at night. This condition is often referred as “nocturnal asthma.” These worsened symptoms are the reason for insomnia and sleep deprivation in many patients with asthma. Worsening of asthma during the night has been reported since the 5th century A.D. and is believed to be affecting a majority of asthmatics.
What are the Symptoms of Nocturnal Asthma?
Common symptoms of nocturnal asthma are similar to asthma and include:
- Wheezing, a screeching sound that occurs when a patient breathes, due to contracted airways.
- Coughing that creates difficulty in sleeping.
- Tightness in the chest.
- Dyspnea which is shortness of breath.
Who is at Risk for Nocturnal Asthma?
Nocturnal asthma is frequently diagnosed in patients suffering from asthma. Having asthma increases the risk of nocturnal asthma. Nocturnal asthma can occur in any form of asthma, such as: occupational asthma, allergic asthma or exercise-induced asthma.
What are the Causes of Nocturnal Asthma?
Functioning of the lungs in asthmatic patients can reduce up to 50% during an episode of nocturnal asthma. The possible explanations may be following:
- Exposure to allergens during night such as animal dander or dust mites can cause Nocturnal Asthma.
- A decrease in cortisone and adrenaline levels lead to Nocturnal Asthma.
- Reflux of stomach acid into the esophagus when sleeping or lying down can cause Nocturnal Asthma.
- Cooling of the airways that cause spasm of the major airways.
- Aspiration into the airways can result in Nocturnal Asthma.
- Sinusitis, postnasal drip and sleep apnea; all of these can trigger Nocturnal Asthma.
What is the Pathophysiology of Nocturnal Asthma?
Allergen Activation of Mast Cell Secretion
In a study, it was found that pulmonary mast cell activation not only provoked acute airway obstruction but, in some asthmatic patients, increased asthma about 6 hours later. Such reaction to antigen has been defined as late phase asthma. Late-phase asthma is an important result of mast cell degranulation and is characteristic of a more chronic phase of asthma with regard to both airway obstruction and responsiveness. The importance of allergen exposure to the pathogenesis of nocturnal wheezing in some asthmatic patients has been shown by a number of investigations. The cause of persistent and recurrent nocturnal asthma can often be elusive, even with a careful questioning of the patient. Therefore, it is important for clinicians to remember that a single exposure to an allergen can begin a cascade of events that leads to an increase in both airway obstruction and hyper-responsiveness.
The role of sleep in the pathogenesis of nocturnal asthma has also been studied considerably. In a study conducted by Lopes and colleagues, total airway resistance and inspiratory muscle activity were measured in five normal adults during sleep. During non-rapid eye movement sleep, total airway resistance increased by a mean of 230% over waking hours. The investigators inferred that changes in total airway resistance, possibly related to an increase in upper airway muscle tone, led to an increase in the work of breathing during sleep. When similar changes occur in patients with asthma, airflow obstruction would be expected to increase to a greater degree. Although obstruction of airflow is associated with sleep, its causative role in asthma needs further investigation.
Diminished Mucociliary Clearance
Mucous plugging causes airway obstruction and occurs in the lungs of patients with persistent asthma. However, retention of airway secretions at night may also contribute to the nocturnal symptoms of less severe asthma. Specific studies are needed to further confirm the role of it in nocturnal asthma.
Increase in ventilation changes the water content in the airway and hence changes the temperature and contributes to asthma during exercise. In a study conducted by Chen and Chai indicated that airway cooling may also contribute to airway obstruction at night. A humid environment for sleep was found favorable to reduce nocturnal asthma but did not complete its occurrence.
Circadian Rhythm of Circulating Hormones and Nervous Tone
Diurnal variations in circulating hormones and parasympathetic tone were found to be the paramount contributors to nocturnal wheezing as per recent studies.
How is the Diagnosis of Nocturnal Asthma Made?
Spirometry is used to measure the amount of expelled air, the time to exhale and the peak flow which gives a measure of the ability of lungs to inhale and exhale.
Vital Capacity Test is used to measure the maximum quantity of air that lungs can breathe in or breathe out at any given time.
Peak Expiratory Flow Rate (PEFR) Test is done to measure maximum flow rate while exhaling as hard as one can. It is also called as peak flow rate test.
Forced Expiratory Volume (FEV1) Test is used to measure the maximum quantity of air lungs can breathe out in one second.
What is the Treatment of Nocturnal Asthma?
Till present, nocturnal asthma is incurable like regular asthma. The chronic condition of nocturnal asthma can only be managed through various methods of standard treatment of asthma.
The key treatment method by medication for nocturnal asthma is available as inhaled steroids, consequently reducing inflammation and other symptoms. One should rely on inhaled steroid daily if they are suffering from nocturnal asthma. Other oral medications, such as montelukast is also reported to be helpful in the nigh time bouts of asthma.
Bronchodilators, such as albuterol and a nebulizer is reported to be really helpful during night time episodes in nocturnal asthma.
Managing Nocturnal Asthma by Treating Its Cause or Triggers
Another way to treat nocturnal asthma is by focusing on the factors that may be contributing to it. Depending on the cause, it might be treated by focusing on the following trigger factors of nocturnal asthma:
Managing Psychological Stress: Stress can be a trigger or cause of nocturnal asthma. Seeing a psychotherapist, physical exercises, relaxation exercises, such as yoga are some of the effective ways to manage stress. Other clinical conditions as anxiety disorders or depression are treated with certain medications.
Treating GERD (Gastroesophageal Reflux Disease): Nocturnal asthma can also occur as a result of GERD. To manage such type of nocturnal asthma, GERD should be treated by avoiding foods that are high in saturated fats, such as fatty meats, fried foods, whole milk and chocolate. Caffeine in coffee or tea should also be avoided, spicy foods, some acidic citrus juices, and soft drinks can irritate the esophagus, as well, so limitation or avoidance is the better approach.
Maintaining a Healthy Weight: Maintaining optimum weight as per height and age is one of best ways to avoid many diseases including nocturnal asthma. Obesity is a major risk factor for both nocturnal asthma and GERD. To maintain a balanced diet, it is important to incorporate foods high in protein, unsaturated fats, and fiber.
Maintaining an exercise routine is also important. Following types of exercises can be incorporated into regime: Aerobic exercises, high-intensity cardio exercises and strength training.
Reducing Smoking Habits: There are several ways to cut down on nicotine consumption, such as nicotine patches, seeing a therapist and attending a group support program.
Removing Allergens: Dust mites and ticks in mattresses can worsen symptoms at night; hence, maintaining hygiene is of utmost importance in patients with nocturnal asthma.
Regulating Room Temperature at Night: Maintaining room temperature is of prime importance in some locations, as extreme weather conditions can cause rapid fluctuations and trigger nocturnal asthma. Therefore regulating room temperature will help in controlling the bouts of nocturnal asthma. A room temperature can be maintained by keeping it insulated, keeping windows or cracks sealed and, using a humidifier in the room.
Exacerbation of symptoms during the night is obligatory rather than the exception in asthma. Factors like the circadian rhythm of blood epinephrine concentration and vagal tone further contribute to its complications. Other factors, such as airway cooling, sleep, and diminished clearance of secretions are speculated to contribute to nocturnal wheezing, but are of lesser importance. Nocturnal asthma is the result of a convoluted interaction of many factors that lead to escalated bronchial obstruction and airway smooth muscle responsiveness. The appearance of nocturnal symptoms of asthma should alert the medical practitioner to the presence of nocturnal asthma and the need to initiate immediate therapy.
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