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A hiccup or hiccough (normally pronounced "HICK-up" (IPA: /ˈhɪkʌp/) regardless of spelling) is an involuntary spasm of the diaphragm; typically this repeats several times a minute. The sudden rush of air into the lungs causes the epiglottis to close, creating the "hic" noise. A bout of hiccups generally resolves itself without intervention, although many home remedies are in circulation that claim to shorten the duration, and medication is occasionally necessary. By extension, the term "hiccup" is also used to describe a small and unrepeated aberration in an otherwise consistent pattern. The medical term is singultus.
While many cases develop spontaneously, hiccups are known to develop often in specific situations, such as eating too quickly, taking a cold drink while eating a hot meal, belching, eating very hot or spicy food, laughing vigorously or coughing, drinking an alcoholic beverage to excess, crying out loud (sobbing causes air to enter the stomach), some smoking situations where abnormal inhalation can occur (in tobacco or other smoke like cannabis, perhaps triggered by precursors to coughing), or electrolyte imbalance. Hiccups may be caused by pressure to the phrenic nerve by other anatomical structures, or rarely by tumors and certain kidney disease. It is reported that 30% of chemotherapy patients suffer singultus as a side effect of treatment. (American Cancer Society) Diaphragmatic irritation can lead to hiccups.
One possible beneficial effect of hiccups is to dislodge foreign pieces of food, which have become stuck in the esophagus, or which are traveling too slowly. When a piece of food is swallowed that is too large for the natural peristalsis of the esophagus to move the food quickly into the stomach, it applies pressure on the phrenic nerve, invoking the hiccup reflex. This causes the diaphragm to contract, creating a vacuum in the thoracic cavity, which creates a region of low pressure on the side of the lump of food nearest the stomach, and a region of high pressure on the side of the lump of food nearest the mouth. This lungs differential across the food creates a force, which assists peristalsis. In humans, gravity partially assists peristalsis, but in quadrupeds and many marine vertebrates, their oesophagi run roughly perpendicular to the force of gravity, so that gravity provides little assistance. The hiccup mechanism likely evolved as an aid to peristalsis in our ancestors. It now only appears to offer little benefit.
Ultrasound scans have also shown that babies in-utero experience hiccups. Some hypotheses suggest that hiccups are a muscle exercise for the respiratory system prior to birth, or that they prevent amniotic fluid from entering the lungs. More research is required to ascertain their true nature, origins, and purpose, if any.
Christian Straus and co-workers at the Respiratory Research Group, University of Calgary, Canada, propose that the hiccup is an evolutionary remnant of earlier amphibian respiration; amphibians such as frogs and toads gulp air and water via a rather simple motor reflex akin to mammalian hiccuping. In support of this idea, they observe that the motor pathways that enable hiccuping form early during fetal development, before the motor pathways that enable normal lung ventilation form; thus according to recapitulation theory the hiccup is evolutionarily antecedent to advanced lung respiration. Additionally, they point out that hiccups and amphibian gulping are inhibited by elevated CO2 and can be completely stopped by the drug Baclofen (a GABAB receptor agonist), illustrating a shared physiology and evolutionary heritage. These proposals would explain why premature infants spend 2.5% of their time hiccuping, indeed they are gulping just like amphibians, as their lungs are not yet fully formed.
Another explanation, the amniotic/atmospheric hypothesis, holds that there are two distinct systems in the brain for controlling respiration: one that is used when the fetus is respiring amniotic fluid during its time in the womb, and another that only comes into use following birth, used for breathing air. Since amniotic fluid is much more viscous than air, a much greater effort is required from the diaphragm to inhale it. If this amniotic breathing system becomes dominant for any reason during life outside the womb, the result will be a momentary, very forceful effort at inhalation. The body senses that things are not correct, and since so much force is actually dangerous to the lungs and other organs, the system is immediately preempted and switched back to the atmospheric system. However, this preemptive control gradually relaxes, making the phenomenon cyclic as long as there is underlying activation of the amniotic respiration system: as the preemptive control falls below the threshold, the amniotic routine resumes control, only to be preempted again, and this cycle continues until the underlying conditions leading to the amniotic breathing activation revert to their normal state – at which point the hiccups stop. This theory is supported by the finding that hiccups are more common in premature newborns, as in these cases the atmospheric respiration system is less prepared to take precedence over the amniotic respiration system.
The following are some commonly suggested home remedies. While numerous remedies are offered, they mostly fall into a few broad categories. These categories include purely psychosomatic cures centered around relaxation and distraction, cures involving swallowing and eating (with the rationale generally that this would remove irritants or reset mechanisms in the affected region), and cures involving controlled/altered breathing.
The first two categories may prove effective for many short lived and minor cases of hiccups. For instance, with an assistant applying pressure to one's ears, drinking any quantity of liquid whilst holding one's nose is a common home remedy for hiccups. However, those suffering from an intractable case may become desperate sorting through various ineffective home remedies. Many of the cures centered around controlled breathing (i.e. holding breath) are often ineffective for prolonged hiccups crisis, but do have a significant efficacy for the most casual, short lasting cases. For these scenarios, the underlying rationale could be the displacement of an irritated nerve through prolonged diaphragmatic expansion.
However, one respiratory remedy has a fairly sound rationale underlying it. Breathing into a bag or small enclosed container (ensuring that it is completely sealed around the mouth and nose) induces a state that is termed respiratory acidosis. The effect is caused by increasing the amount of inspired carbon dioxide, which then increases the level of carbon dioxide in the serum. These increased levels of CO2 lower the pH in the blood, hence creating a state of acidosis. This state of acidosis produces vasodilation and depression of the central nervous system. The effect allows for increased blood flow to the affected muscles, and suppression of the aberrant nervous impulses. Inducing a state of acidemia through hypoventilation is particularly effective in curing hiccups because the diaphragm rests directly against the pulmonary vasculature that is then flowing with especially low pH blood. This is a potentially dangerous action; and should only be done with another person present. As the serum CO2 level rises abruptly, the person will begin to feel lightheaded and within a few minutes will pass out. If done without a spotter, the person might either injure him or herself as he or she passes out, or pass out in such a way that the bag or container continues to prevent oxygen intake (see also asphyxia).
Additionally, another respiratory remedy appears to be of the most effective in treating persistent hiccups. One breathes out all the air that they are able to in one long exhalation then breathes in all the air they feel they possibly can in one continuous inhalation. The person then attempts to breathe in even more air in a series of short powerful puffs, until their lungs cannot hold any more. The person remains in this state for as long as they feel a small gas bubble coming at the very base of the throat, ready to be burped. Although the success rate is not 100%, many people find this method consistently works. One scientific explanation for this method is that, by breathing an extreme load of air, the lungs tend to take more space in the chest, applying pressure on the surrounding content. The so-called gas bubble, which was located in an abnormal location potentially disturbing a nerve and causing the spasm, is then released. Psychosomatic
- Distraction from one's hiccup (e.g. being startled, asked a perplexing question, or counting in reverse from 100 down)
- Concentration on one's hiccups - using sheer will to stop them
- Breathing slowly and deeply in while thinking 'breathing out' and breathing slowly and fully out while thinking 'breathing in'
- Holding one's breath while optionally squeezing one's stomach
- Breathing deeply through the nose, then exhaling slowly through the mouth
- Exhaling all the air from one's lungs and holding one's breath while swallowing water or saliva
- Smoking a cigarette
- Blowing up a balloon
- Inducing sneezing
- In babies, hiccups are usually immediately stopped by the suckling reflex, either by breastfeeding or simply by insertion of a finger, bottle teat or dummy into the baby's mouth.
- Take your right hand, and push it on your left arm.
- Pinch your ear lobe and breath normally. Can turn into second-nature (psychosomatic). *Works on some Dogs too.
- Giving the person suffering from hiccups a sudden and unexpected fright (for example, by shouting at them) can have the effect of ending a bout of hiccups.
Ordinary hiccups are cured easily without medical intervention; in most cases they can be stopped simply by forgetting about them. However, there are a number of anecdotally prescribed treatments for casual cases of hiccups. These include being startled, drinking water while upside down, eating something very sweet, for example a tart (particularly lemon juice) , and anything that interrupts one's breathing. Another method is to exhale air into a small paper bag and to immediately re-inhale that air from it.Drink water quickly and vigorous burping.
Hiccups are treated medically only in severe and persistent (termed "intractable") cases (such as in the case of a 15 year old girl who in 2007 hiccuped continuously for five weeks ). Haloperidol (Haldol, an anti-psychotic and sedative), metoclopramide (Reglan, a gastrointestinal stimulant), and chlorpromazine (Thorazine, an anti-psychotic with strong sedative effects) are used in cases of intractable hiccups. In severe or resistant cases, baclofen (an anti-spasmodic) is sometimes required to suppress hiccups. Effective treatment with sedatives often requires a dose that renders the person either unconscious or highly lethargic. Hence, medicating singultus is done short-term, as the affected individual cannot continue with normal life activities while taking the medication.
Persistent and intractable hiccups due to electrolyte imbalance (hypokalemia, hyponatremia) may benefit from drinking a carbonated beverage containing salt to balance out the potassium-sodium tae in the nervous system. The carbonation promotes quicker absorption.
The administration of intranasal vinegar is thought to be safe and handy method to stimulate dorsal wall of nasopharynx, where the pharyngeal branch of the glossopharyngeal nerve (afferent of the hiccup reflex arc) is distributed.
Dr. Bryan R. Payne, a neurosurgeon at the Louisiana State University Health Sciences Center in New Orleans, has had some success with an experimental new procedure in which a vagus nerve stimulator is implanted in the upper chest of patients with an intractable case of hiccups. "It sends rhythmic bursts of electricity to the brain by way of the vagus nerve, which passes through the neck. The Food and Drug Administration approved the vagus nerve stimulator in 1997 as a way to control seizures in some patients with epilepsy. In 2005, the agency endorsed the use of the stimulator as a treatment of last resort for people with severe depression."
In 2006, Francis Fesmire of the University of Tennessee College of Medicine received an Ig Nobel prize for medicine after he published "Termination of intractable hiccups with digital rectal massage" in 1988. In an attempt to block the runaway messages on the vagus nerve, Fesmire found that stimulation of the vagus nerve by digital rectal massage worked, stopping a bout of hiccupping. 
American man Charles Osborne had the hiccups for 68 years, from 1922 to 1990, and was entered in the Guinness World Records as the man with the Longest Attack of Hiccups.
In January 2007, teenager Jennifer Mee from Florida in the United States hiccuped for five weeks, from January 23, 2007 until February 28, 2007.
A man in Lincolnshire, England was reported to have had hiccups for at least twenty two weeks from February 2007.
A man who lives in Belfast, Northern Ireland has had intractable hiccups for five years and has had two major operations so far to try to stop his hiccups.
- Straus, C. (2003 Feb). "A phylogenetic hypothesis for the origin of hiccough.". BioEssays 25 (2): 182-188. 10.1002/bies.10224. Retrieved on 2007-07-20.
- Kahrilas, P.J. (1997 Nov). "Why do we hiccup?". Gut 41 (5): 712-713. Retrieved on 2007-07-20.
- Iwasaki et al., "Hiccup treated by administration of intranasal vinegar", In: No To Hattatsu. 2007 May;39(3):202-5. 
- Fesmire F. (1988). "Termination of intractable hiccups by digital rectal massage". Ann Emerg Med 17: 872.
- "Florida girl hiccuping again after returning to school", msnbc.msn.com, March 16, 2007.
- "Man suffers five year hiccup bout", news.bbc.co.uk, July 19, 2007. From July 6, 2007 to July 9, 2007, Brad Nicol of Santa Barbara, California had the hiccups. "It hurt a lot," he said.
- Hiccups - Considerations, Causes and Home Care (Healthbasis.com)
- Hiccups (WebMD)
- The Straight Dope: What are hiccups and why do we get them?
- Termination of intractable hiccups with digital rectal massage.
- Cures for Hiccups
- BBC News:Why we hiccup
- Retrospective analysis of hiccups in patients at a community hospital from 1995-2000.
Symptoms and signs: respiratory system (R04–R07, 786)
|; Respiratory sounds:
|Chest, general||* Chest pain|
Symptoms and signs: digestive system and abdomen (R10–R19, 787,789)
|Abdominal – general|
Symptoms and signs: skin and subcutaneous tissue (R20-R23, 782)
|Disturbances of skin sensation||Hypoesthesia - Paresthesia - Hyperesthesia|
|Other||Rash - Cyanosis - Pallor - Flushing - Petechia - Desquamation - Induration - Diaphoresis|
Symptoms and signs: nervous and musculoskeletal systems (R25-R29, 781)
|Abnormal involuntary movements|
(see also movement disorders)
|Tremor - Spasm - Fasciculation - Athetosis|
|Gait abnormality||Scissor gait - Antalgic gait - Cerebellar ataxia - Festinating gait - Pigeon gait - Propulsive gait - Steppage gait - Stomping gait - Spastic gait - Myopathic gait - Magnetic gait - Trendelenburg gait|
|Lack of coordination||Ataxia (Cerebellar ataxia, Sensory ataxia) - Dysmetria - Dysdiadochokinesia - Hypotonia|
|Other||Tetany - Meningism - Hyperreflexia - Opisthotonus - Abnormal posturing - Hemispatial neglect|
Symptoms and signs: urinary system (R30-R39, 788)
|General||Renal colic - Dysuria - Vesical tenesmus - Urinary incontinence - Urinary retention - Oliguria - Polyuria - Nocturia - Extravasation of urine - Extrarenal uremia|
Symptoms and signs: cognition, perception, emotional state and behaviour (R40-R46, 780-781)
|General||Anxiety - Somnolence - Coma - Amnesia (Anterograde amnesia, Retrograde amnesia) - Dizziness/Vertigo|
|Olfaction||Anosmia - Parosmia|
|Taste||Ageusia - Parageusia|
Symptoms and signs: Speech and voice (R47-R49, 784)
|Aphasia/Dysphasia||Expressive aphasia - Receptive aphasia - Conduction aphasia|
|Other speech disturbances||Dysarthria - Schizophasia|
|Symbolic dysfunctions||Dyslexia - Alexia - Agnosia (Prosopagnosia) - Apraxia - Acalculia - Agraphia|
|Voice disturbances||Dysphonia - Aphonia|
Symptoms and signs: general (R50-R69, 780-789)
|General||Fever (Hyperpyrexia) - Headache - Chronic pain - Malaise/Fatigue (Asthenia, Debility) - Fainting (Vasovagal syncope) - Febrile seizure - Shock (Cardiogenic shock) - Lymphadenopathy - Edema (Peripheral edema, Anasarca) - Hyperhidrosis (Sleep hyperhidrosis) - Delayed milestone - Failure to thrive - Short stature (Idiopathic) - food and fluid intake (Anorexia, Polydipsia, Polyphagia) - Cachexia - Xerostomia - Clubbing - Tenderness|
Symptoms and signs: Symptoms concerning nutrition, metabolism and development (R62–R64, 783)
|Growth||Delayed milestone • Failure to thrive • Short stature (e.g., Idiopathic)|