Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0012833 (dizziness)
 9,689 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hyperventilation is of little clinical relevance unless it causes symptoms. These are often non-specific. Their threshold for onset and relation to steady level of arterial (or its equivalent, end-tidal PCO2; PETCO2) are uncertain, and it has been suggested that they may relate better to the rate of fall of PCO2 than to the absolute level. We investigated this in nine normal subjects, who breathed to and fro through a pneumotachograph into an open circuit in which the concentration of CO2 could be varied. Tidal volume, respiratory frequency and ventilation was measured on-line by a Compaq computer, and PETCO2 at the mouth was measured by capnograph. Subjects overbreathed at a fixed rate and depth until symptoms consisting of dizziness, paraesthesiae and light headedness occurred. Then, without their knowledge and while they continued to overbreathe, inspired CO2 was increased to restore PETCO2 to normal and abolish symptoms, and was then withdrawn again over either approximately 0.1, 2.5 or 5 min until symptoms were again reported. The PETCO2 at this point was noted. The three protocols were performed in each subject in a random order and the same symptoms were reported each time. When averaged across all subjects, symptoms occurred at mean PETCO2 values of 20.3, 19.2 and 18.6 mmHg (2.71, 2.56 and 2.48 kPa), respectively. These were not significantly different, and it can be concluded that there was no influence of rate of fall of PCO2 on threshold for symptoms. Chest pain only occurred in one subject and may have a different mechanism.
 ...
PMID:Relation of hypocapnic symptoms to rate of fall of end-tidal PCO2 in normal subjects. 144 88

Thyrotropin-releasing hormone (TRH) stimulates pituitary thyrotropin synthesis and release and also regulates autonomic nervous system functions by acting as a neuromodulator and neurotransmitter. In experimental animals a stimulation of ventilation by thyrotropin-releasing hormone was shown when applied at central nervous system sites that affect respiratory motor output. It was the goal of our study to investigate the respiratory properties of thyrotropin-releasing hormone on basal and stimulated (i.e. CO2-rebreathing) conditions following systemic thyrotropin-releasing hormone application in healthy humans. Thyrotropin-releasing hormone (200 micrograms, 400 micrograms intravenous) initiated a rapid short lasting rise of minute volume, ventilatory air-flow and alveolar oxygen tension under steady state breathing (P less than 0.001). Breathing frequency was less affected, heart rate rose concomitantly (P less than 0.001). While breathing with increasing concentrations of carbon dioxide, minute volume was higher under thyrotropin-releasing hormone than under placebo alone. Further effects (e.g. nausea, dizziness, palpitations) mostly appeared later than respiratory changes and thus may not be responsible for their initiation. Our findings prove systemic thyrotropin-releasing hormone to be a strong respiratory stimulant in man. Response in respiratory output was also accompanied by central nervous system-effects (e.g. dizziness, restlessness, augmented vigilance). The mode of thyrotropin-releasing hormone effects on respiration after peripheral administration is still speculative. An augmented sympathetic output or a direct receptor mediated action at central nervous system sites may be responsible, while a peripheral effect cannot be excluded.
 ...
PMID:Thyrotropin-releasing hormone has stimulatory effects on ventilation in humans. 190 74

This clinical study was preceded by two laboratory experiments. The first experiment compared temperature changes in the vestibule while vaporizing a 0.6-mm stapedotomy with Argon, KTP-532, and CO2 lasers. Data demonstrated that the CO2 laser possesses superior tissue characteristics for stapedotomy. In the second experiment safe energy parameters were established for various Sharplan CO2 laser models. Using these safe power settings, 153 consecutive CO2 laser stapedotomies were performed under local anesthesia. No patient experienced intraoperative dizziness during or immediately following the application of the CO2 laser to the stapes footplate. Long-term postoperative hearing results demonstrated that 87% of the patients maintained an air/bone gap to within 10 dB and 94% maintained an air/bone gap to within 15 dB (mean follow-up 32 months). No patient incurred a significant sensorineural hearing loss (greater than 10 dB) in the speech range. Four patients developed a perilymph fistula (three immediate and one delayed) and fluctuating sensorineural hearing loss, but all were successfully repaired without significant permanent nerve deafness. At 4,000 Hz, five patients lost 20 dB and two patients dropped 40 dB compared with preoperative levels. Postoperative complications included four perilymph fistulas, two prostheses displaced from the stapedotomy opening, one fixed prosthesis, and one fixed incus. Seven of eight of these complications were successfully revised. At the time of this writing, 6/153 patients have a persistent conductive hearing loss greater than 20 dB and have not been revised. Using appropriate energy parameters, the CO2 laser provides a safe, efficient microsurgical tool for performing stapedotomy simply and with minimum inner ear trauma.
 ...
PMID:CO2 laser stapedotomy. 229 97

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.
 ...
PMID:Effect of nalbuphine hydrochloride on the ventilatory and occlusion pressure responses to carbon dioxide in volunteers. 250 65

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.
 ...
PMID:Responses to hypercarbia induced by acetazolamide in panic disorder patients. 210 41

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.
 ...
PMID:Ferrihaemoglobin formation by amyl nitrite and sodium nitrite in different species in vivo and in vitro. 290 49

Acute altitude illnesses include acute mountain sickness (AMS), a benign condition involving headache, nausea, vomiting, irritability, insomnia, dizziness, lethargy, and peripheral edema, and potentially lethal high-altitude cerebral edema and pulmonary edema (HAPE). Recent evidence is summarized that AMS is related to cerebral edema secondary at least in part to hypoxic cerebral vasodilation and elevated cerebral capillary hydrostatic pressure. This results in reduced brain compliance with compression of intracranial structures in the absence of altered global brain metabolism. It is postulated that these primary intracranial events elevate peripheral sympathetic activity that acts neurogenically in the lung possibly in concert with pulmonary capillary stress failure to cause HAPE and in the kidney to promote salt and water retention. The adrenergic responses are likely modulated by striking increases of aldosterone, vasopressin and atrial natriuretic peptide. The effects of exercise on altitude-induced illness and various therapeutic regimens (acetazolamide, CO2 breathing, dexamethasone, and alpha adrenergic inhibitors) are discussed in light of this hypothesis.
 ...
PMID:A neurogenic basis for acute altitude illness. 816 37

In recent years in the literature on stapes surgery several changes have been proposed concerning the adoption either of new technologies (Laser) or of surgical techniques preserving middle ear functional structures (stapedoplasty). The Authors carried out a personal case-report on 30 patients suffering from otospongiotic disease, in order to clarify the real advantages and possible applications of the latest developments in small fenestra stapedectomy. Twenty subjects underwent platinotomy with preservation of the stapedial tendon (stapedoplasty), while a simple stapedotomy was performed in the remaining 10 cases, with or without inversion of surgical times (a "rigid system" technique was adopted in 7 patients). CO2 Laser was used on 10 of these patients (33%) in order to carry out certain surgical steps; in particular it was used on 7 subjects who underwent stapedotomy with stapedoplasty (35%) and in 3 cases of traditional stapedotomy (100%). An audiometric examination was conducted on all subjects 1 and 6 months after the operation, in order to evaluate functional recovery; the post-operative stapedial reflex was also studied in patients who underwent stapedoplasty. This research points out the advantages that CO2 Laser gives in the execution of stapes surgery, whatever the type of technique adopted; in particular, the advantages of using this instrument are: -an easier and bloodless performance of the operation, particularly in the case of the preservation of the stapedial tendon; -a greater regularity and precision of the footplate hole than that obtained by drilling, especially in subjects whose stapes are thin, floating, fractured or even obliterated; -less mechanical traumatism on the labyrinth during either the fracturing of the crura or the footplate fenestration, resulting in the reduction of both perceptive hearing loss an dizziness; -a higher incidence of air-bone gap closure mostly in the case of stapedial tendon preservation. On the other hand, the use of inadequate lasers or the lack of reference to exact parameters (beam power and frequence, time of exposure and defocalization), could cause the heating of labyrinthine liquids and so damage the receptorial structures of the inner ear.
 ...
PMID:[Evolution of the operative technique. CO2 laser stapedotomy and stapedoplasty]. 892 68

The positive CO2 pneumoperitoneum needed to create the working space for laparoscopic surgery induces cardiovascular, neuroendocrine, and renal changes. Concern about these pathophysiologic changes has led to the introduction of a gasless technique. Fifty consecutive patients with symptomatic gallstones were randomized to conventional (CLC) or gasless laparoscopic cholecystectomy (GLC), with special reference to overall patient satisfaction, technical difficulties, duration of surgery, postoperative pain, and recovery. The overall exposure of the operative field was extremely poor in the GLC group, whereas the duration of surgery, steps involved in the cholecystectomy technique, length of hospital stay, and postoperative pain score did not differ significantly. After discharge, the median time to complete relief of pain tended to be shorter in the gasless group (5 days [range 1 to 15]) vs. the conventional group (8 days [range 1 to 15]). The period to return to normal activity was shorter in the GLC group (6 days [range 1 to 15]) compared to the CLC group (8.5 days [range 1 to 15]) (P = 0.031). No differences were found in terms of fatigue, dizziness and nausea, and overall satisfaction with the outcome. This study demonstrates a significantly shorter convalescence after laparoscopic cholecystectomy by means of the gasless technique compared to the conventional CO2 technique. Exposure of the operative field was less than optimal using the gasless technique.
 ...
PMID:Randomized comparison of conventional and gasless laparoscopic cholecystectomy: operative technique, postoperative course, and recovery. 1136 58

This stratified cross-sectional epidemiological study included 1053 school children aged 13-17 years. All pupils filled in a questionnaire on building-related symptoms and other relevant health aspects. The following exposure measurements were carried out: room temperature, CO2 level, and relative humidity; building characteristics including mold infestation were assessed, and dust was collected from floors, air, and ventilation ducts during a working day. Dust was examined for endotoxin level, and cultivated for viable molds. We did not find a positive association between building-related symptoms and extent of moisture and mold growth in the school buildings. Five of eight building-related symptoms were significantly and positively associated with the concentration of colony forming units of molds in floor dust: eye irritation, throat irritation, headache, concentration problems, and dizziness. After adjusting for different potentially confounding factors in separate analyses of each symptom, the above-mentioned associations between molds in dust and symptoms were still present, except for concentration problems. However, in none of the analyses was mold exposure the strongest covariate, being secondary to either asthma, hay fever, recent airway infection, or psychosocial factors.
 ...
PMID:Molds in floor dust and building-related symptoms in adolescent school children. 1475 47


1 2 Next >>