Seasickness is a pathological condition that occurs as a result of sea rolling. It is manifested by nausea, dizziness, cephalgia, vomiting, malaise, deviations in the emotional sphere (apathy / excitement), falling blood pressure, arrhythmia. Diagnosis is carried out on the basis of typical clinical symptoms. For the purpose of professional selection, instrumental methods of vestibular function research are used. Depending on the manifestations, therapy is carried out by a combination of several drugs of the following groups: cholinolytics, antiemetics, antihistamines, psychostimulants, nootropics.
General information
Seasickness is an integral part of the concept of “kinetosis” (motion sickness), which includes various types of motion sickness: air sickness, motion sickness in motor transport, amusement rides, horse riding. Symptoms of kinetosis in appropriate conditions are detected in 60% of children, 30% of adults. The marine form belongs to the most severe variants of kinetosis. Strong pitching can cause motion sickness of any person, only 3% of people are absolutely resistant to its effects. Seasickness is most often observed in children 2-12 years old, less often in the elderly. Young people are more susceptible to the disease, according to some data, about 2/3 of sailors younger than 25 years suffer from seasickness. Women are less resistant to motion sickness than men. In children under 2 years of age, the symptoms of pathology during sea travel are practically not detected.
Causes
The main etiofactor of kinetosis is the effect on the vestibular apparatus of multidirectional accelerations exceeding the usual threshold stimuli. There are three forms of pitching: vertical (lifting-sinking of the ship), keel (oscillations around the transverse axis of the ship), side (oscillations around the longitudinal axis). On large ships, vertical pitching is felt weakly, but keel and side are significant. A number of factors are known that increase the likelihood of developing marine kinetosis, these include:
- The intense nature of the pitching. Slow smooth rolling is carried much easier than fast rapid. The pitching period (the time the ship moves between extreme positions) depends on the degree of sea disturbance, size, tonnage of the vessel.
- Alcohol intake, fatty foods, overeating. These factors negatively affect the state of the body, reduce the resistance to pitching. The abuse of food and alcohol, the intake of carbonated drinks 1-2 days before the start of the voyage can provoke marine kinetosis.
- Adverse environmental impacts. The likelihood of seasickness increases with the action of several adverse factors. So, in the engine and boiler room of the ship, noise, vibration, air with harmful impurities act on the sailors.
- Chronic diseases. Cardiovascular pathologies, cholelithiasis, chronic gastritis, nephrolithiasis are accompanied by hypersensitivity of the receptor apparatus of the affected organ. As a result, minor accelerations cause a violent vegetosomatic reaction.
- Pathology of the central nervous system. Organic, functional diseases of the central nervous system cause hyperexcitability, inadequate response of central structures that perceive impulses from peripheral receptors. In such conditions, enhanced statokinetic effects during pitching easily provoke kinetosis.
- Optical factor. Constantly moving objects in front of the eyes contribute to motion sickness. Irritation of the visual analyzer, similar to vestibular, can cause dizziness and nausea.
- Psychoemotional state. A tendency to anxiety-depressive states, self-absorption, a sense of fear increase the likelihood of motion sickness. Concentration of attention on a certain activity, sleep help to overcome kinetosis.
Pathogenesis
Despite its widespread occurrence, the mechanism of pathology development has not been definitively studied. Many researchers believe that seasickness is associated with the response of the central nervous system to increased afferent impulses. The peripheral vestibular analyzer is located in the inner ear. The receptors of the semicircular tubules perceive angular acceleration, the otolith organ — linear and gravitational acceleration. The received information on the vestibular nerve is transmitted to the central nervous system, supplemented by impulses from proprio- and baroreceptors. The result of processing the received afferent information is a response impulse going to the muscles, somatic organs, vegetative centers and aimed at adapting the body to the prevailing conditions. At the same time, many vegetative-visceral reactions occur, causing the main symptoms of kinetosis.
According to the theory of “sensory conflict”, the inconsistency of sensory information entering the central nervous system is of decisive importance. Confirmation is the aggravation of symptoms in the cabin, when vestibuloreceptor impulses indicate constant movement, and visual — the absence of movement of surrounding objects. Similarly, some experienced pilots who fly as passengers have air sickness. The usual combination of vestibular and visual information in the cockpit is replaced by a combination of identical vestibular sensations with a different visual afferentation due to the situation in the cabin of the aircraft.
Classification
Seasickness has variable clinical manifestations. The clinical polymorphism of the condition formed the basis of several classifications. Below are the two main ones.
According to the prevailing clinical manifestations , there are 4 forms:
- Nervous. The clinical picture is dominated by cephalgia, heaviness in the head, dizziness, drowsiness. Possible deterioration of vision, hearing.
- Gastrointestinal. It is accompanied by nausea, vomiting, a change in taste sensations, a feeling of an unpleasant aftertaste, a decrease in appetite. In some cases, there is an intolerance to the smell of tobacco smoke, burnt food, etc.
- Cardiovascular. It is typical for people with cardiovascular pathology. It begins with tachycardia, increased blood pressure, palpitations, arrhythmias. Subsequently, bradycardia, arterial hypotension occurs.
- Mixed. It occurs most often. Clinically manifested by a variable combination of symptoms of various forms.
According to the mental characteristics of the course, seasickness is classified into 3 variants:
- Asthenic. The patient is depressed, asthenized, tired quickly, somewhat inhibited. The mood background is lowered.
- Agitated. Excessive talkativeness, fussiness, mobility, increased emotionality, theatricality of speech, pretentiousness of movements are noted.
- Mixed. It is an alternation of periods of asthenization and agitation. It is possible that one variant of the mental reaction prevails.
Symptoms
The symptoms are characterized by significant polymorphism. Some patients experience apathy, weakness, lie on a cot, others hurriedly walk around the deck, excited, extremely talkative. Dizziness, cephalgia, nausea, vomiting giving temporary relief are typical. Diplopia, chills, increased salivation may be detected. Patients complain of a lack of appetite, rejection of many odors, changes in taste sensations. Disorders of the motor function of the gastrointestinal tract are not uncommon: diarrhea, constipation. States of motion sickness are extremely difficult to tolerate, accompanied by pronounced changes in the psycho-emotional sphere.
In mild cases, seasickness is limited to 2-3 days of dizziness, nausea. In severe cases, the patient is pale, the face is covered with cold sweat, there is bradycardia, repeated vomiting, increased respiratory rate, possible cardiac arrhythmias, movement coordination disorder, pressure drop, confused state of consciousness. Sometimes seasickness has a hidden course. There is asthenization, a decrease in performance without obvious clinical manifestations of kinetosis. The absence of vivid symptoms makes it impossible to diagnose the latent form in a timely manner. Such a situation is dangerous if a sick team member receives a task that requires responsible execution.
Diagnostics
Diagnostic measures include anamnesis collection (absence of symptoms before the trip, presence of chronic diseases), detailed complaints, assessment of the general status, neurological examination of the patient. It is necessary to exclude diseases of the gastrointestinal tract, intestinal infection, cardiovascular diseases. The study of the neurological status does not reveal meningeal symptoms, focal neurological deficit, allows rejecting the probability of neuroinfection (meningitis, encephalitis). Diagnosis of predisposition to kinetosis is necessary for the professional selection of seafarers. Evaluation of the vestibular analyzer is carried out by the following methods:
- Vestibulometry is the study of the reaction of the vestibular apparatus to various stimuli. It is carried out by using devices that simulate the effects of various forms of accelerations.
- Caloric sample. Gives an idea of the excitability of the labyrinth, allows you to identify the labyrinth pathology.
- Rotational tests. They are required to determine the adaptive ability of the vestibular apparatus in conditions of rotation. They are carried out with the help of a special chair, where the subject is located.
- Video oculography. It makes it possible to detect a hidden nystagmus, indicating a subclinical pathology of the labyrinth.
Treatment
You can reduce the symptoms of motion sickness by eliminating aggravating factors. Frequent light meals in small portions with the exception of fatty, whole milk, carbonated liquids are necessary. It is useful to drink water, tea with cranberry juice, lemon. Facilitates the state of resorption of lollipops, crackers. It is recommended to stand on the deck, fixing your gaze on the horizon line, or take a horizontal position in the cabin (optimal — to fall asleep). Pharmaceutical preparations with an anticoagulant effect include:
- Cholinolytics (hyoscyamine, platyphylline). They were widely used at the end of the XX century, due to pronounced side effects, they are currently used only to a limited extent. Scopolamine is the most effective. A special application form of the drug in the form of a patch allows for uniform diffusion of scopolamine into the blood, which significantly levels the side effect.
- Sodium bicarbonate. It has shown high effectiveness against motion sickness. Intravenous infusions and rectal candles are prescribed.
- Antihistamines (dimenhydrinate, meclozin, promethazine). Block histamine receptors of the inner ear, vestibular nuclei, reducing vestibulovegetative reactions. They are well tolerated, used prophylactically.
- Psychostimulants (mesocarb, caffeine). They are prescribed in combination with antihistamines / cholinolytics. Reduce the side effect in the form of central nervous system depression.
- Antiemetic (metoclopramide). They are necessary for the relief of repeated vomiting.
- Nootropics (aminophenylbutyric acid, piracetam). They increase the adaptive capabilities of the central nervous system, improve cerebral metabolism.
- Combined pharmaceuticals. They are a combination of several similar pharmaceuticals (scopolamine + hyoscyamine), means of various mechanisms of action (antihistamine + psychostimulant).
Prognosis and prevention
Seasickness passes when the pitching stops. In some patients, weakness and dizziness persist for several days. Measures to prevent kinetosis are the exclusion of provoking factors, training of the vestibular apparatus, preventive pharmacotherapy. Before swimming and during the trip, it is recommended to refrain from taking carbonated / alcoholic beverages, limit smoking, avoid overeating, overheating in the sun, tracking flashing objects. Regular physical activity contributes to increased resistance to motion sickness. Vestibular training is provided by exercises with head rotation, rotations, sports games (football, volleyball), dancing, aerobics, acrobatics. Drug prevention is carried out with antihistamines. An early increase in the adaptive abilities of the nervous system is carried out by conducting course therapy with adaptogens, means that improve cerebral hemodynamics, neuroprotectors.