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Query: UMLS:C0027497 (nausea)
 23,468 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acute mountain sickness is a pathologic reaction as a result of bad adaptation to high altitudes (greater than 2.500 meters). The main symptoms are headache, nausea, vomits, and insomnia. When severe it can produce oliguria, retinal hemorrhage, ataxia and sometimes coma. Its etiology is not well known. It is considered that the first producer factor of the disease is tissular hypoxia secondary to low partial oxygen pressure existing in areas of high sea level. The treatment consists of descent and the use of dexametasone and acetazolamide.
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PMID:[Acute mountain sickness]. 210 53

Between 1983 and 1990 a total of 74 freestyle mountaineers and 88 mountaineers with skis attempted to climb Mount Agri (Ararat). From the freestyle group two mountaineers were affected by acclimatisation disorder at 3200 m and seven at 4200 m above sea level. Acute mountain sickness (AMS) affected four mountaineers at 4200 m, eight at 4700 m, two at 5000 m and two at 5165 m, while 49 reached the summit. Only one of the mountaineers with skis was affected by AMS (at 4200 m), while all the others reached the summit. The symptoms of acclimatisation disorder and AMS, according to their degree of frequency, were headache, weakness, dyspnoea and palpitation, anorexia, nausea, vomiting, giddiness, ataxia and insomnia. Pulse rates varied between 115 and 124/min, and breathing between 30 and 38/min.
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PMID:Cases of acute mountain sickness on Mount Agri. 803 91

Acute mountain sickness (AMS) affects, to varying degrees, all travelers to high altitudes (elevations greater than 5280 feet). In a small percentage of patients, AMS can lead to high-altitude pulmonary edema (HAPE) or high-altitude cerebral edema (HACE). Symptoms of AMS range from a combination of headache, insomnia, anorexia, nausea, and dizziness, to more serious manifestations, such as vomiting, dyspnea, muscle weakness, oliguria, peripheral edema, and retinal hemorrhage. Although the primary cause of these symptoms is related to the reduced oxygen content and humidity of the ambient air at high altitudes, the physiologic pathway relating hypoxemia to AMS and its sequelae remains unclear. Tips on self-diagnosis and symptom recognition are critical elements to be included in educating patients who are contemplating a trip to high altitudes. Preventive strategies include allowing 2 days of acclimatization before engaging in strenuous exercise at high altitudes, avoiding alcohol, and increasing fluid intake. Conditioning exercise for patients older than 35 years is also recommended before departure. A high-carbohydrate, low-fat, low-salt diet can also aid in preventing the onset of AMS. Acetazolamide (125 mg two or three times daily, or once at bedtime) has also been shown to reduce susceptibility to AMS and the incidence of HAPE and HACE. Although effective in treating cerebral symptoms of AMS, dexamethasone is not routinely recommended as a prophylactic agent for AMS.
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PMID:A trek to the top: a review of acute mountain sickness. 855 56

Acute mountain sickness (AMS) has long been recognised as a potentially life-threatening condition afflicting otherwise healthy normal individuals who ascend rapidly to high altitude where the partial pressure of oxygen (pO2) in the air is reduce. The symptoms of AMS (e.g. headache, poor appetite and nausea, fatigue and weakness, dizziness or light-headedness and poor sleep) are probably a consequence of disturbances in fluid balance brought about by severe tissue hypoxia. AMS can be prevented by an adequately slow ascent, which is the best method, but for those with limited time there are several drug therapies that provide a relatively good protection. Acetazolamide (250 mg twice daily or 500 mg slow release once daily), taken before and during, ascent is probably the treatment of choice; it improves gas exchange and exercise performance and reduces the symptoms of AMS in most individuals. Dexamethasone (4 mg, 4 times daily) is more of value for short term treatment or prevention, and should never be used for more than 2 to 3 days. Prophylactic use of progesterone looks promising, but more studies are required.
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PMID:Medicine and mechanisms in altitude sickness. Recommendations. 857 Sep 99

Acute mountain sickness and high altitude cerebral edema are specific pathologies of high altitude exposure. The usual symptoms of acute mountain sickness are headache, nausea, vomiting, insomnia, lassitude, dizziness and ataxia. High altitude cerebral oedema is a severe state of acute mountain sickness with, in addition, alteration of mental status and consciousness. The pathophysiology of these 2 diseases are essentially due to an increase of intracranial pressure directly dependent of an increase of cerebral volume. Molecular and cellular mechanisms underlying acute mountain sickness and high altitude cerebral oedema are still poorly understood. The regulation of cerebral blood flow by nitric oxide seems to play a major role.
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PMID:[High altitude cerebral oedema]. 1281 24

Acute mountain sickness (AMS) develops within a few hours after arrival at high altitude and includes headache, anorexia, nausea, vomiting, and malaise. This afflicts 15-25% of the general tourist population at moderate altitudes. High-altitude cerebral edema (HACE) is considered to be the end stage of severe AMS and has been suggested to be a vasogenic edema, raising the possibility that acute hypoxia may increase blood-brain barrier (BBB) permeability. At present, there are no good small-animal models to study this syndrome. We hypothesize 1) that acute hypoxia can damage the BBB and 2) that rat can be used as a model to study hypoxia-induced changes in BBB permeability, especially if hypoxia-induced hypothermia could be minimized with high ambient temperature (HAT). Male Wistar rats were exposed to 1, 2, and 7 days of hypobaric hypoxia (equivalent to 0.5 atm), and changes in the temperature and BBB permeability were studied. The extravasation of endogenous immunoglobulin G, a large molecule, did not increase during room temperature hypoxia but did increase when hypoxia was combined with HAT. Hypoxia caused a significant increase in the leakage of sodium fluorescein (mol wt 376 Da). The expression of endothelial barrier antigen (EBA), a protein associated with the BBB, was reduced to 50% between 24 and 48 h after exposure to hypoxia, and the loss was exacerbated by HAT. The values almost returned to control levels by 7 days, showing adaptation to hypoxia. Hypoxic rats exhibited sodium fluorescein leakage mainly in focal areas in the brain parenchyma. In conclusion, it is possible to have transient BBB damage through exposure to acute hypoxia, and this damage is exacerbated by increasing body temperature to more of a normothermic value.
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PMID:Effects of acute hypoxia and hyperthermia on the permeability of the blood-brain barrier in adult rats. 1964 26

Acute mountain sickness (AMS) develops in people trekking at high altitude. The underlying mechanism is vasodilation due to low pressure of oxygen. However, individual susceptibility for AMS is unknown, thus, one cannot predict when or to whom it happens. Because AMS usually begins with headache, and because migraineurs are more vulnerable to AMS, we studied by the literatures review on the mechanism and clinical features in common, and assessed the treatment modalities for both disorders. This led to us the following hypothesis that, migraine prophylaxis may prevent or delay the onset of AMS at high altitude. Clinical features of AMS include nausea or vomiting when it progresses. Hypobaric hypoxia, dehydration or increased physical exertion trigger or aggravate both disorders. In migraine, cerebral vasodilation can happen following alteration of neuronal activity, whereas the AMS is associated with peripheral vessel dilation. Medications that dilate the vessels worsen both conditions. Acute treatment strategies for migraine overlap with to those of AMS, including drugs such as vasoconstrictors, or other analgesics. To prevent AMS, adaptation to high altitude or pharmacological prophylaxis, i.e., acetazolamide has been recommended. This carbonic anhydrase inhibitor lowers serum potassium level, and thus stabilizes membrane excitability. Acetazolamide is also effective on specific forms of migraine. Taken together, these evidences implicate that migraine prophylaxis may prevent or delay the onset of AMS by elevating the threshold for high altitude.
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PMID:Can migraine prophylaxis prevent acute mountain sickness at high altitude? 2185 88

Acute mountain sickness (AMS) is characterized by headache often accompanied by gastrointestinal complaints that vary from anorexia through nausea to vomiting. The aim of this study was to investigate the influence of high altitude on plasma levels of gastroenteropancreatic (GEP) peptides and their association to AMS symptoms. Plasma levels of 6 GEP peptides were measured by radioimmunoassay in 11 subjects at 490 m (Munich, Germany) and, after rapid passive ascent to 3454 m (Jungfraujoch, Switzerland), over the course of three days. In a second study (n = 5), the same peptides and ghrelin were measured in subjects who consumed standardized liquid meals at these two elevations. AMS symptoms and oxygen saturation were monitored. In the first study, both fasting (morning 8 a.m.) and stimulated (evening 8 p.m.) plasma levels of pancreatic polypeptide (PP) and cholecystokinin (CCK) were significantly lower at high altitude as compared to baseline, whereas gastrin and motilin concentrations were significantly increased. Fasting plasma neurotensin was significantly enhanced whereas stimulated levels were reduced. Both fasting and stimulated plasma motilin levels correlated with gastrointestinal symptom severity (r = 0.294, p = 0.05, and r = 0.41, p = 0.006, respectively). Mean O(2)-saturation dropped from 96% to 88% at high altitude. In the second study, meal-stimulated integrated (= area under curve) plasma CCK, PP, and neurotensin values were significantly suppressed at high altitude, whereas integrated levels of gastrin were increased and integrated VIP and ghrelin levels were unchanged. In summary, our data show that acute exposure to a hypobaric hypoxic environment causes significant changes in fasting and stimulated plasma levels of GEP peptides over consecutive days and after a standardized meal. The changes of peptide levels were not uniform. Based on the inhibition of PP and neurotensin release a reduction of the cholinergic tone can be postulated.
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PMID:Influence of acute exposure to high altitude on basal and postprandial plasma levels of gastroenteropancreatic peptides. 2297 Feb 20

Altitude physiology began with Paul Bert in 1878. Chronic mountain sickness (CMS) was defined by Carlos Monge in the 1940s in the Peruvian Andes as consisting of excess polycythemia. Hurtado et al performed studies in the Peruvian Andes in the 1950s to 1960s which defined acclimatization in healthy altitude natives, including polycythemia, moderate pulmonary hypertension, and low systemic blood pressure (BP). Electrocardiographic changes of right ventricular hypertrophy (RVH) were noted. Acclimatization of newcomers to altitude involves hyperventilation stimulated by hypoxia and is usually benign. Acute mountain sickness (AMS) in travelers to altitude is characterized by hypoxia-induced anorexia, dyspnea, headache, insomnia, and nausea. The extremes of AMS are high-altitude cerebral edema and high-altitude pulmonary edema. The susceptible high-altitude resident can lose their tolerance to altitude and develop CMS, also referred to as Monge disease. The CMS includes extreme polycythemia, severe RVH, excess pulmonary hypertension, low systemic BP, arterial oxygen desaturation, and hypoventilation.
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PMID:Cardiovascular medicine at high altitude. 2389 41

Acute mountain sickness (AMS) is the most common high altitude illnesses experienced during rapid ascent to a higher altitude without prior acclimation. It is mainly characterized by a headache which may be accompanied with nausea, vomiting, anorexia, dizziness, lethargy, fatigue, and sleep disturbance. If not diagnosed and treated in a timely manner, AMS can develop into deadly high altitude pulmonary edema or high altitude cerebral edema. In the previous studies of individual variation in susceptibility to AMS, arterial oxygen saturation (SO2) was identified as being associated with AMS. However, other studies have reported no association between AMS and arterial oxygen saturation. In this study, the association between SO2 and AMS was assessed through a meta-analysis of published data. The literature databases PubMed, Web of Science, LWW, Science Direct, and Embase were queried for papers published before 15 April 2014. A fixed-effects model and a random-effects model were applied (Revman 5.0) on the basis of heterogeneity, and the study quality was assessed in duplicate. Twelve studies with 614 AMS patients and 1,025 control subjects were analyzed. There was a significant association with differences in SO2 and the risk of developing AMS. SO2 values are associated with AMS incidence.
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PMID:Association of arterial oxygen saturation and acute mountain sickness susceptibility: a meta-analysis. 2496 66


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