Seasickness
From Wikipedia, the free encyclopedia
| Sea-sickness Classification and external resources |
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| ICD-10 | T75.3 |
|---|---|
| ICD-9 | 994.6 |
Seasickness is a form of motion sickness characterized by a feeling of nausea and, in extreme cases, vertigo experienced after spending time on a craft on water.[1] It is typically brought on by the rocking motion of the craft. Some people who are particularly vulnerable to the condition with minor stimulus and will feel seasick simply by setting foot on a boat, even if the vessel is in dry dock while others are relatively immune, or become immune through exposure.[1]
Seasickness can be a debilitating condition and can be dangerous if the sufferer has an important role to carry out, such as steering a yacht through stormy seas while avoiding rocks and other hazards.[1] It is also particularly hazardous for scuba divers[2] who, through dehydration following vomiting, are at increased risk of decompression illness.
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[edit] Cause
Human beings instinctively seek to remain upright by keeping their centre of gravity over their feet. The most important way this is achieved is by visual reference to surrounding objects, such as the horizon. Seasickness often results from the visual confusion on a moving craft, when nearby objects move with the motion of the craft. Because the lines of the masts, windows, and furniture on a ship are constantly shifting with respect to fixed references, humans can suffer a number of afflictions, especially those unaccustomed to being at sea.
Sea-sickness has such a remarkable effect because both the sense of sight and touch are disturbed by the motion of a craft on water. The severity of seasickness is also influenced by the irregular pressure of the bowels against the diaphragm as they shift with the rising and falling of the ship.
In his book The Human Body, Isaac Asimov related the anecdote about a seasick passenger whom a steward cheerfully assured that nobody ever died from seasickness. The passenger muttered, "Please--it's only the hope of dying that's keeping me alive."
Many experience similar effects while not at sea:
- in railway carriages
- in automobiles
- on swings
- while looking from a lofty precipice where known objects, being distant, are viewed under a new aspect and not so readily recognised
- while walking on a wall or roof
- while looking directly up to a roof
- while observing the stars in the zenith
- on walking into a round room, where there are no perpendicular lines of light and shade and the walls and ceiling are covered with an irregularly-spotted design
- on twirling round, as in waltzing
- while watching video captured by an unsteady camera
[edit] Prevention and remedy
Over-the-counter and prescription medications such as dramamine[3] and scopolamine[4] (as transdermal patches and tablets) are readily available though SCUBA divers must evaluate the risks versus the benefits.[5][6][7][8] Ginger capsules are also considered effective in preventing motion sickness.[9] Some sufferers find that wearing special wristbands helps stave off the condition.[10][11]
Those suffering from seasickness who are unaccustomed to the motion of a ship often find relief by:
- by keeping one finger over one ear (blocking one ear). This stops the balancing liquid near your ears from moving around, therefore stopping the brain from detecting any motion sickness
- keep your mind occupied
- taking anti-seasickness/nausea capsules
- keeping their eyes directed to the fixed shore or horizon, where possible
- lying down on their backs and closing their eyes
- drinking any substance that is likely to temporarily diminish their senses of sight and touch
- move into a position where fresh air is blowing on their face
- sucking on crystallised ginger, sipping ginger tea or taking a capsule of ginger.
- moving to the boat's center of gravity to eliminate motion due to pitch, roll and yaw (but not translation)
- taking the helm of a yacht can reduce sickness as the sufferer has something to concentrate on, and can also anticipate the movement of the vessel
Unlike other causes of nausea, such as drinking excessive alcohol or eating spoiled food, vomiting does not usually relieve the feelings of nausea, and instead can lead to exacerbated nausea and further vomiting.
[edit] References
- ^ a b c Benson AJ (2002). "35", Motion Sickness. In: Medical Aspects of Harsh Environments 2. Retrieved on 2008-05-09.
- ^ Norfleet WT, Peterson RE, Hamilton RW, Olstad CS (January 1992). "Susceptibility of divers in open water to motion sickness". Undersea Biomed Res 19 (1): 41–7. PMID 1536062.
- ^ Weinstein SE, Stern RM (October 1997). "Comparison of marezine and dramamine in preventing symptoms of motion sickness". Aviat Space Environ Med 68 (10): 890–4. PMID 9327113.
- ^ Spinks AB, Wasiak J, Villanueva EV, Bernath V (2007). "Scopolamine (hyoscine) for preventing and treating motion sickness". Cochrane Database Syst Rev (3): CD002851. doi:. PMID 17636710.
- ^ Schwartz, HJC and Curley, MD (1986). "Transdermal Scopolamine in the Hyperbaric Environment.". US Naval Experimental Diving Unit Technical Report NEDU-2-86.
- ^ Bitterman N, Eilender E, Melamed Y (May 1991). "Hyperbaric oxygen and scopolamine". Undersea Biomed Res 18 (3): 167–74. PMID 1853467.
- ^ Williams TH, Wilkinson AR, Davis FM, Frampton CM (March 1988). "Effects of transcutaneous scopolamine and depth on diver performance". Undersea Biomed Res 15 (2): 89–98. PMID 3363755.
- ^ Arieli R, Shupak A, Shachal B, Shenedrey A, Ertracht O, Rashkovan G (1999). "Effect of the anti-motion-sickness medication cinnarizine on central nervous system oxygen toxicity". Undersea Hyperb Med 26 (2): 105–9. PMID 10372430.
- ^ Ernst, E.; and M. H. Pittler (2000). "Efficacy of ginger for nausea and vomiting: a systematic review of randomized clinical trials" (PDF). British Journal of Anaesthesia 84 (3): 367–371.
- ^ Gahlinger PM (2000). "A comparison of motion sickness remedies in severe sea conditions". Wilderness Environ Med 11 (2): 136–7. PMID 10921365.
- ^ Bertolucci LE, DiDario B (December 1995). "Efficacy of a portable acustimulation device in controlling seasickness". Aviat Space Environ Med 66 (12): 1155–8. PMID 8747609.
[edit] See also
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