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Query: UMLS:C0012833 (dizziness)
 9,689 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We studied the effect of nalbuphine on the ventilatory and occlusion pressure responses to carbon dioxide rebreathing in six healthy male volunteers (mean age 25.5 yr) in a single-blind laboratory study. On four separate days volunteers were assigned randomly to receive either placebo (0.9% sodium chloride) or three i.v. doses of nalbuphine (15, 30 and 60 mg 70 kg-1), followed 90 min later by naloxone 0.4 mg 70 kg-1. Duplicate rebreathing tests were performed and the mean intercept at PE'CO2 7 kPa and the slopes of the linear relationship between inspiratory minute ventilation (Vl) or occlusion pressure (P0.1) with PE'CO2 were measured. Nalbuphine significantly decreased the mean intercept of the Vl (P less than 0.01) and P0.1 (P less than 0.05) responses, but caused no changes in the slopes. No significant difference between the doses was noted, suggesting that an Effect maximum (E'max) for respiratory depression was reached with a dose of approximately 15 mg 70 kg-1. Naloxone was less effective in antagonizing the depression in Vl at the higher dose of nalbuphine. Similar P0.1 values were associated with the same inspiratory flow rate (1 litre s-1) before and after drug treatment, suggesting that nalbuphine acts centrally to depress ventilation. Sedation increased significantly following each dose of nalbuphine (P less than 0.001). No demonstrable difference between the doses was shown, suggesting an Effect maximum (E'max) for sedation was reached at about 15 mg 70 kg-1. Administration of nalbuphine was associated with pain at the injection site, dizziness, dreaming, nausea and vomiting. Cardiovascular stability was maintained in all subjects.
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PMID:Effect of nalbuphine hydrochloride on the ventilatory and occlusion pressure responses to carbon dioxide in volunteers. 250 65

From a prospective study of 152 patients admitted to an emergency department on account of "malaise" (i.e. dizziness with or without syncope), the authors have extracted a number of interesting points. After 24 hours under observation with questioning, physical examination and measurement of blood alcohol, glucose and carbon dioxide levels, the cause of the "malaise" could be determined in 84 per cent of the patients. Among 37 patients who were detained for more than 24 hours, only 3 additional diagnoses were made. Patients with syncope had the same cause of dizziness as those without syncope. One hundred and nineteen patients were followed up for one year. The mortality rate in patients with a cardiovascular cause of "malaise" was significantly higher than in patients with other causes. Patients with dizziness of unknown origin had the same mortality rate. Patients of more than 70 years of age had a mortality rate (50 per cent) significantly higher than that of patients aged less than 70 (25 per cent). Finally, the patient's history and physical examination proved to be the most helpful aids in establishing the cause of the "malaise".
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PMID:["Malaise" at an emergency department. Diagnostic approach]. 252 49

Regional cerebral blood flow (CBF), mood states and somatic symptoms were measured before and after inhalation of amyl nitrite in 10 physically healthy volunteers with a prior history of using volatile nitrites for recreational purposes. CBF was measured with the same technique, under identical laboratory conditions, in an equal number of normal volunteers. During CBF measurements, blood pressure, pulse rate, respiratory rate and end-tidal levels of carbon dioxide were monitored. The amyl nitrite group and the control group were compared on CBF, rating scale scores and physiological indices via analysis of variance. Amyl nitrite inhalation was associated with significant global increases in CBF, while the control group did not show any change. Pulse rate increase was the only physiological change associated with administration of the drug. Subjects who received the drug reported significant decrease in anger, fatigue and depression and increased palpitation, breathing difficulty, dizziness and headache. Changes in the rating scale scores, physiological indices, and somatic symptoms after amyl nitrite did not correlate with regional CBF change.
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PMID:Regional cerebral blood flow changes associated with amyl nitrite inhalation. 270 85

CO2 inhalation has been reported to induce panic attacks in panic disorder patients. State anxiety, somatic symptoms of anxiety, physiological changes, and cerebral blood flow (CBF) were monitored in panic disorder patients before and after intravenous injections of 1 g of acetazolamide (13 patients) and saline (10 patients), given under double-blind conditions. In spite of significant hypercarbia, as evidenced by increased CBF in the former group, only one subject reported panic and even that attack did not meet DSM-III-R criteria. There was only one significant difference between the drug and placebo groups; the acetazolamide group experienced significantly more dizziness.
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PMID:Responses to hypercarbia induced by acetazolamide in panic disorder patients. 210 41

Carbon monoxide poisoning causes tissue hypoxia because of reduced transfer and altered release of oxygen by hemoglobin. Considering many case histories, we realized that symptoms and clinical signs of acute poisoning are mostly neurologic: coma, headache, dizziness, vomiting. On the contrary, it seems that myocardium, the other organ which mostly requires O2, is attacked in a "silent way". ECG in 5 patients with accidental carbon monoxide poisoning underlined that cardiac rate increased (3 of them presented tachyarrhythmias by atrial fibrillation) and the presence of more or less important alteration of ventricular repolarization like "subendocardial lesion". Simple hyperbaric oxygen treatment determined the regression of the rhythm disorder and of the abnormalities of ventricular repolarization. The only patient who had not the restoration of sinus rhythm had chronic atrial fibrillation.
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PMID:[Cardiologic aspects of carbon monoxide poisoning]. 275 46

The ferrihaemoglobin (HbFe3+) formation by amyl nitrite (AN) or sodium nitrite (NaNO2) was studied in different species including man, in vivo and in vitro. In in vivo studies AN was administered intravenously (i.v.), intramuscularly (i.m.), by inhalation, or orally. NaNO2 was injected i.v.. AN i.v. produced HbFe3+ much more rapidly than NaNO2 in dogs, cats, rabbits, and rats. In dogs, i.m. injection of AN was followed by a very slow linear increase in the HbFe3+ content. Inhalation of AN did not lead to HbFe3+ formation in dogs unless it was rebreathed in a closed (bag) or not completely open (gas mask) system. HbFe3+ was produced by oral AN in dogs, the effect being enhanced by addition of DMSO. Inhalation of AN by human volunteers in a gas mask and from ampoules crushed close to the nose did not induce haemoglobin oxidation to a practically significant extent, but it was associated with headache, tiredness, dizziness, and a fall in blood pressure. In in vitro studies, in contrast to NaNO2, AN produced HbFe3+ instantaneously in erythrocytes of various species and in purified human haemoglobin. AN 1 mol yielded 2 mol Fe3+. Only 20% of the oxygen released during the oxidation of haemoglobin by AN or NaNO2 was recovered. In 0.2 M phosphate buffer, pH 7.4, 0.01 mol O2/mol AN was consumed. CO2 was released in the presence of AN, but not of NaNO2, from blood, plasma, and 0.02 M NaHCO3 solution. The ratio (lactate)/(pyruvate) decreased when HbFe3+ was formed by AN or NaNO2.
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PMID:Ferrihaemoglobin formation by amyl nitrite and sodium nitrite in different species in vivo and in vitro. 290 49

Headache and dizziness are early symptoms of carbon monoxide poisoning, occurring at carboxyhemoglobin levels of greater than 10 percent. Previously, it was shown that among patients presenting to an emergency department during the winter with headache or dizziness, an algorithm for obtaining carboxyhemoglobin levels on patients who used gas stoves for heating purposes or who had similarly affected cohabitants correctly identified all patients with carboxyhemoglobin levels greater than 10 percent. To test the validity of this retrospectively derived rule, 65 patients were studied who were unaware of any carbon monoxide exposure and who presented during the winter of 1986-1987 with headache or dizziness. The algorithm correctly identified three of four patients with carboxyhemoglobin levels greater than 10 percent (sensitivity = 75 percent) and correctly excluded 45 of 61 patients with lower levels (specificity = 74 percent). The presence of symptomatic cohabitants alone was an equally sensitive (75 percent) but more specific (90 percent) marker for elevated carboxyhemoglobin levels. When data from the two cohorts were combined, stepwise multiple regression identified number of cigarettes smoked daily (F = 8.66) and concurrently symptomatic cohabitants (F = 34.71) as significant predictors of the carboxyhemoglobin level. It is concluded that a retrospectively derived rule correctly identified most cases of occult carbon monoxide poisoning when applied prospectively, and that the presence of similarly affected cohabitants was the most reliable marker for a carbon monoxide-mediated illness.
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PMID:Occult carbon monoxide poisoning: validation of a prediction model. 340 53

Subacute carbon monoxide poisoning is commonly misdiagnosed as an influenza-like viral illness. All patients presenting to the triage nurse at University Hospital with flu-like symptoms during February 1985 were asked to give blood samples for carboxyhemoglobin determination. Fifty-five patients (10% of those eligible) with headache, dizziness, nausea, vomiting, diarrhea, weakness, general malaise, or shortness of breath were enrolled in the study. Carboxyhemoglobin levels ranged from 0 to 21%. Thirteen patients (23.6%) of this self-selected subgroup had carboxyhemoglobin levels greater than or equal to 10%. There was no statistically significant difference in carboxyhemoglobin levels between smokers and nonsmokers. More patients using wood heat had elevated carboxyhemoglobin levels than patients using any other form of heating (P less than .05). No patient with a carboxyhemoglobin level greater than or equal to 10% was diagnosed as having subacute CO poisoning by emergency physicians. Physicians must seek out the possibility of CO toxicity in patients with flu-like illness, particularly in inner-city populations during the heating months. Fundoscopy and COHb levels may be useful in selected cases to correctly diagnose patients and avoid a return to a hazardous environment with potentially fatal consequences.
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PMID:Carboxyhemoglobin levels in patients with flu-like symptoms. 359 33

Headache and dizziness occur at carboxyhemoglobin levels of greater than 10%. We studied 89 patients with headache or dizziness for evidence of carbon monoxide exposure. The mean carboxyhemoglobin level was 2.87%. Number of cigarettes smoked per day (r = 0.471; p less than 0.00002), use of gas kitchen stoves for heating purposes (r = 0.252, p less than 0.02), problems with the home heating system (r = 0.278, p less than 0.01), and cohabitants with concurrent headache or dizziness (r = 0.427, p less than 0.01) correlated with carboxyhemoglobin levels. Multiple regression analysis identified number of cigarettes smoked daily, use of stoves for heat, and concurrently symptomatic cohabitants as significant predictors of carboxyhemoglobin level (F = 13.939 [3, 85]; p less than 0.01). Obtaining carboxyhemoglobin levels from patients who used stoves for heat or had similarly affected cohabitants identified 4 of 4 patients with levels greater than 10% (sensitivity, 100%) and excluded 47 of 85 patients with lower levels (specificity, 55.3%). The 4 patients with carboxyhemoglobin levels in excess of 10% may represent occult carbon monoxide poisoning in this population.
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PMID:Predictors of occult carbon monoxide poisoning in patients with headache and dizziness. 360 95

A total of 65 students and one female teacher were afflicted with an unusual illness following alleged inhalation of a 'gas' in the school. The main symptoms were dizziness, chills, nausea, headache, difficulty in breathing and faintness. Initial investigations revealed elevated carboxyhaemoglobin levels (greater than 5%) of 16 hospitalized students. However, no sources of carbon monoxide emission could be detected despite extensive environmental investigations. The outbreak was characterized by the following features: most victims were adolescent girls; there was a high proportion of recurrences; the illness was self-limiting with inconsistent clinical and epidemiological findings; its mode of transmission was associated with antecedent visual observation or verbal information, and it died down immediately after confidence had been restored. A diagnosis of mass psychogenic illness was made. The high-risk students were Malay girls who were from the normal class (for slow learners), engaged in part-time employment and easily influenced by what they had heard or seen.
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PMID:Epidemiological enquiries into a school outbreak of an unusual illness. 361 Apr 54


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