A hiccup, known medically as singultus, is a common, typically brief, involuntary action that affects the respiratory system. The heart does not stop beating during a hiccup, contrary to a common misconception often fueled by the startling sensation that accompanies the involuntary spasm. This reflex is usually benign and self-limiting, resolving on its own within a few minutes.
The Definite Answer: Hiccups and Heart Rhythm
The heart continues beating throughout a bout of hiccups because cardiac function is managed by its own electrical system. The unsettling feeling some people experience in their chest is related to the sudden, sharp movement of the diaphragm, a muscle located directly beneath the heart and lungs.
The hiccup forces a rapid intake of air, which is then abruptly blocked by the closing of the vocal cords. This sudden mechanical event causes a momentary jolt or pressure change within the chest cavity. The vagus nerve, which helps regulate both the hiccup reflex and the heart rate, may cause the heart rhythm to briefly alter. This minor variation is a temporary autonomic nervous system response and does not mean the heart has stopped or paused its function.
The Spasm: What Causes a Hiccup
A hiccup is characterized by a spasmodic, involuntary contraction of the diaphragm muscle, which is the primary muscle of respiration. This sudden, forceful downward movement causes a rapid, unintended inhalation of air into the lungs.
Immediately following the diaphragm’s contraction, the glottis, the opening between the vocal cords, snaps shut in about 35 milliseconds. This abrupt closure blocks the incoming air, creating the distinctive “hic” sound. The entire action is governed by a reflex arc involving specific nerves that transmit signals between the brain and the diaphragm.
The reflex arc involves the vagus nerve, the phrenic nerve, and sympathetic fibers. The phrenic nerve provides the motor signal to the diaphragm, causing it to contract. When this reflex arc is irritated or stimulated, it triggers the involuntary spasm. Common irritants include eating too quickly, drinking carbonated beverages, or experiencing sudden excitement.
Simple Remedies and Underlying Physiology
Many methods for stopping hiccups work by attempting to interrupt the reflex arc through stimulation or changes in breathing. Techniques like holding one’s breath or breathing into a paper bag increase the concentration of carbon dioxide in the blood. This rise in carbon dioxide suppresses the hiccup reflex by forcing the body to focus on regulating normal breathing patterns.
Other remedies, such as gargling with ice water or swallowing granulated sugar, function by stimulating the vagus nerve in the throat. Since the vagus nerve plays a role in the hiccup reflex, this stimulation is thought to overload the nerve pathway, effectively resetting the reflex. Forcibly changing the pattern of diaphragm movement or applying gentle pressure to the upper abdomen also aims to disrupt the rhythmic spasm.
When to Seek Medical Advice
A bout of hiccups is usually transient, resolving on its own within a few minutes to an hour. Hiccups that last longer than 48 hours are classified as persistent, and those continuing for more than a month are called intractable. When hiccups become persistent or intractable, they can interfere with eating, sleeping, and speaking, significantly affecting quality of life.
These longer episodes may signal an underlying medical condition that requires professional attention. Causes can range from irritation along the vagus or phrenic nerves to issues like gastroesophageal reflux disease (GERD). More serious causes include central nervous system disorders or tumors that compress the involved nerves. If hiccups extend beyond two days, consulting a healthcare provider is prudent to identify and treat any potential root cause.