Losing consciousness from coughing too hard is possible, a phenomenon medically termed cough syncope. This temporary loss of consciousness occurs directly after a severe coughing episode. This article will explain the mechanisms involved, factors that increase susceptibility, and when it becomes necessary to consult a healthcare professional.
Understanding How It Happens
A forceful cough generates a rapid increase in pressure within the chest cavity, known as intrathoracic pressure. This pressure surge can reach up to 300 mm Hg during intense coughing, mimicking the Valsalva maneuver. Elevated intrathoracic pressure compresses large veins returning blood to the heart, significantly reducing venous return. This decreases the heart’s ability to pump blood effectively, leading to a temporary reduction in cardiac output and a drop in systemic blood pressure.
Decreased cardiac output and blood pressure can lead to a reduction in blood flow to the brain, known as cerebral hypoperfusion. The brain requires a continuous supply of oxygenated blood, and even a brief interruption can result in a transient loss of consciousness. Some theories suggest that increased intrathoracic pressure can transmit to the cerebrospinal fluid, elevating intracranial pressure and further compromising cerebral blood flow.
Another contributing factor is a neurally mediated reflex response. Intense pressure changes during coughing can stimulate baroreceptors, specialized sensors in blood vessels that monitor blood pressure. This stimulation can trigger a reflex causing peripheral vasodilation and a further drop in blood pressure, sometimes accompanied by a slowed heart rate. The combination of reduced blood return to the heart and reflex-induced vasodilation diminishes cerebral perfusion, leading to syncope.
Factors That Increase Risk
Certain conditions and individual characteristics can increase a person’s susceptibility to cough syncope. Chronic cough, a persistent cough lasting eight weeks or more, is a primary trigger. This type of cough often results from underlying respiratory conditions like asthma, chronic obstructive pulmonary disease (COPD), or respiratory infections such as pertussis. Frequent, forceful coughing fits associated with these conditions can induce syncope.
Individual factors also play a role in experiencing cough syncope. It is more commonly observed in middle-aged men, particularly those who are overweight or muscular. Smoking, both current and former, is a prevalent risk factor, often contributing to chronic lung diseases. These traits suggest that factors contributing to higher intrathoracic pressure and compromised respiratory function may increase vulnerability.
Pre-existing medical conditions can further elevate the risk. Cardiovascular conditions, such as hypertension or impaired cerebral blood flow, can make individuals more prone to fainting during a severe cough. Certain medications, like angiotensin-converting enzyme (ACE) inhibitors, are known to cause chronic cough as a side effect and can contribute to cough syncope. Other medications, including some anti-hypertensives, vasodilators, and diuretics, might also exacerbate the hypotensive response, increasing fainting risk.
When to Consult a Doctor
While an isolated episode of cough syncope may not always indicate a severe problem, recurrent episodes warrant medical attention. Fainting carries the risk of injury from falling. Seek professional advice if the loss of consciousness is prolonged or if an injury occurs during a syncopal event.
Consult a doctor if cough syncope is accompanied by other concerning symptoms. These might include chest pain, shortness of breath, or neurological symptoms such as numbness, weakness, or vision changes. Such symptoms could suggest a more serious underlying medical condition requiring prompt diagnosis and treatment. A healthcare provider can evaluate the cough, assess for underlying diseases, and determine the appropriate course of action.