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Query: UMLS:C0018681 (headache)
 56,091 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cerebral blood flow velocity (CBFv) was measured by insonating the middle cerebral arteries of four subjects using a 2 Mhz transcranial Doppler. Ambient CO2 was elevated to 0.7% for 23 d in the first study and to 1.2% for 23 d in the same subjects in the second study. By non-parametric testing CBFv was elevated significantly by +35% above pre-exposure levels during the first 1-3 d at both exposure levels, after which CBFv progressively readjusted to pre-exposure levels. Despite similar CBFv responses, headache was only reported during the initial phase of exposure to 1.2% CO2. Vascular reactivity to CO2 assessed by rebreathing showed a similar pattern with the CBFv increases early in the exposures being greater than those elicited later. An increase in metabolic rate of the visual cortex was evoked by having the subjects open and close their eyes during a visual stimulus. Evoked CBFv responses measured in the posterior cerebral artery were also elevated in the first 1-3 d of both studies returning to pre-exposure levels as hypercapnia continued. Cerebral vascular autoregulation assessed by raising head pressure during 10 degrees head-down tilt both during the low-level exposures and during rebreathing was unaltered. There were no changes in the retinal microcirculation during serial fundoscopy studies. The time-dependent changes in CO2 vascular reactivity might be due either to retention of bicarbonate in brain extracellular fluid or to progressive increases in ventilation, or both. Cerebral vascular autoregulation appears preserved during chronic exposure to these low levels of ambient CO2.
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PMID:Effects of sustained low-level elevations of carbon dioxide on cerebral blood flow and autoregulation of the intracerebral arteries in humans. 954 68

Carbon dioxide laser is a continuous wave laser, it is well known for its capacity of tremendous smoke production while contact with tissue. Smoke may cause nausea, vomiting, headache and airway irritation. Smoke particles 0.5-2 micrometers in diameter usually travel down the tracheobronchial tree and lodge in the alveoli posing a health hazard. The objectives of this study were to evaluate possible health hazards of carbon dioxide laser smoke in the operating room environment, by determining the size and density of smoke particles also determine the efficacy of surgical masks as a smoke protectant. Ten fresh specimens of papillomatous tissue obtained from the patients were lased by carbon dioxide laser in a continuous mode. The plume generated was collected by 0.45 micrometers pore size microfilter which was attached to the tip of a suction hose connecting the smoke evacuator. The effectiveness of 2 types of commonly used surgical masks were also determined by trapping the smoke after passing through each mask using the same model. Smoke particles were evaluated by scanning electron microscope. The smoke particle density of microfilter that directly trap plume averaged 6 particles/mm2, particles ranging in size from 0.5-27 micrometers, of which 70 per cent were 0.8 micrometers. For the particles trapped after passing through both cotton and paper surgical mask, the size were ranging from 1.6-37 micrometers where 65 per cent were 3.7 micrometers and the particle density average 2.7/mm2. We concluded that the smoke particles derived from carbon dioxide laser application are within the alveolar hazard zone. The conventional surgical masks may not be an effective tool against laser smoke hazard.
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PMID:The potential alveolar hazard of carbon dioxide laser-induced smoke. 962 22

A seventy year old right handed woman presented progressive limb apraxia and headache due to carbon monoxide poisoning. Thereafter, when in hospital for one week, she developed akinetic mutism, coma and died. Limb apraxia has been rather uncommonly reported in carbon monoxide poisoning. The akinetic mutism observed after the patient had been removed from intoxication could be analysed as a delayed encephalopathy related to a chronic carbon monoxide poisoning.
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PMID:[Gesture apraxia disclosing carbon monoxide poisoning]. 968 68

In patients with cystic fibrosis (CF), nasal intermittent positive pressure ventilation (NIPPV) is currently used as a short-term bridge to transplantation but its precise role has yet to be determined. Patients were offered a therapeutic trial of NIPPV when candidates for lung transplantation, with respiratory failure unresponsive to medical treatment. Twelve patients, six male of mean age of 26 +/- 1.4 years, had a trial of NIPPV. At recruitment the mean percentage predicted forced expired volume in one second (FEV1) was 15.1% +/- 1.2%, arterial carbon dioxide (PaCO2) 8.7 +/- 0.6 kPa, arterial oxygen (PaO2) with variable FiO2 7.4 +/- 0.6 kPa and arterial bicarbonate (HCO3-) 40.1 +/- 1.6 mmol l-1. Ten cases tolerated NIPPV for 1-15 months, mean 5.1 +/- 1.4 months, with subjective improvement in headache and quality of sleep. At 3 months, there was significant improvement in forced vital capacity, PaCO2 and arterial HCO3- and there was a reduction in the number of hospital inpatient days (P < 0.05). Subsequently three cases had lung transplantation, four died on the active list and three are awaiting organs. Two patients failed to tolerate NIPPV owing to abdominal bloating and increasing hypercapnia. In conclusion, NIPPV, if tolerated, was a useful adjunct in the treatment of CF patients with hypercapnic respiratory failure awaiting transplantation. Further prospective studies are required to determine the optimum time to commence NIPPV and to clarify its precise role.
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PMID:Long-term nasal intermittent positive pressure ventilation in patients with cystic fibrosis and hypercapnic respiratory failure (1991-1996). 969 16

The prophylactic effect of metoprolol in the treatment of migraine is well known, but its mode of action is still unclear. In the past, increased CO2 reactivity has been reported as one pathognomic finding in interictal migraineurs. Using transcranial Doppler we assessed CO2 reactivity in 20 migraineurs before and 3 h after the first intake of 50 mg metoprolol, and subsequently twice after 1 and 8 weeks of continuous therapy with 150 mg metoprolol/d. Before initiation of therapy, migraineurs as a group had increased CO2 reactivity (p=0.07) compared to 20 age- and sex-matched volunteers. While treatment with metoprolol has been reported to affect amplitudes of increased contingent negative variation or visual evoked potentials in interictal migraineurs, it had no influence on enhanced CO2 reactivity in the present study. Moreover, the pretreatment value of CO2 reactivity did not correlate with the clinical efficacy of metoprolol after a 2-month treatment period.
Cephalalgia
PMID:No effect of prophylactic treatment with metoprolol on cerebrovascular CO2 reactivity in migraineurs. 973 41

The use of isolation helmets has gained popularity as a method of possible protection of the operating-room personnel from diseases that can be transmitted during operative procedures. However, the use of these systems has been associated with a variety of symptoms, including fatigue, diaphoresis, nausea, headache, and irritability. These symptoms have often been attributed to the mental stress of the operative procedure or the physical discomfort of the helmet. As far as we know, no manufacturers include the measured levels of carbon dioxide or the rate of air exchange of their helmet system. A possible common cause of discomfort with helmet systems is the level of carbon dioxide to which the person wearing the device is exposed. We measured the levels of carbon dioxide in four helmet systems from three different manufacturers during light exercise designed to approximate the exertion during an orthopaedic operation. All but one unit failed to meet the exposure limits recommended by the National Institute for Occupational Safety and Health and the Occupational Safety and Health Administration regarding exposure to carbon dioxide. One unit, the Stackhouse Freedom Aire self-contained system, did meet these standards, but the levels of carbon dioxide in this helmet were more than 1000 per cent greater than the ambient levels in air (440 parts per million compared with 4939 parts per million). Isolation systems must be evaluated carefully not only for comfort but also for the physiological effects caused by exposure to elevated levels of carbon dioxide. Operating-room personnel who use such systems should be aware that many of the physical symptoms that they experience may be associated with elevated levels of carbon dioxide.
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PMID:Levels of carbon dioxide in helmet systems used during orthopaedic operations. 975 9

Carbon monoxide (CO) poisoning continues to be a significant health problem both in the United States and in many other countries. CO poisoning is associated with a high incidence of severe morbidity and mortality. Epidemics of CO poisoning commonly occur during winter months and sources include: smoke from fires, fumes from heating systems burning fuels, and exhaust fumes from motor vehicles. The history of exposure and carboxyhemoglobin levels should alert the physician to this diagnosis. In the absence of exposure history, CO poisoning should be considered when two or more patients are simultaneously sick. The clinical presentation is non-specific and may range from nausea and headache to profound central nervous system dysfunction. The mainstay of therapy for CO poisoning is supplemental oxygen, ventilatory support, and monitoring for cardiac dysrhythmias. This article reviews up-to-date information of this potentially devastating exposure.
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PMID:Carbon monoxide poisoning: a review for clinicians. 1059 2

Various chemicals found in the environment have been suspected of initiating or contributing to conditions such as asthma, dermatitis, irritability, headaches, cardiac arrhythmias, thrombophlebitis, and vasculitis. The increasing number and variety of chemicals present in the environment has led to the hypothesis that there may also be a corresponding increase in the number of people who are sensitive to these chemicals. Sensitive individuals may be continually exposed to chemical insults in their normal environment and may be experiencing a chronic reaction; however, an exposure-response relationship is difficult to establish. An Environmental Care Unit (ECU) provides an atmosphere that minimizes exposures to potential insults so patients symptoms of reaction to chemical insult may be relieved before challenge testing. Air quality required within an ECU to achieve this symptom remission is not known; therefore, this study was designed to document and compare concentrations of six criteria pollutants (sulfur dioxide, carbon monoxide, nitrogen dioxide, hydrocarbons, total suspended particular, and ozone) and formaldehyde within the ECU, the hospital outside the ECU, and the ambient atmosphere of the neighborhood around the hospital. Air movement studies indicated that the ECU was under positive pressure with respect to the rest of the hospital and had an air supply to air exhaust ratio of approximately two. Overall, no significant differences were found for any sampled pollutant at sites within the ECU or between ECU sites and the hospital proper. With an exception of ozone, significant differences among contaminant concentrations were noted between the atmosphere of the surrounding neighborhood and the hospital proper.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The determination of ambient air quality within an environmental care unit. 1028 81

Over the past seven years, the U.S. Environmental Protection Agency has consistently ranked indoor air pollution among the top five risks to public health. One of the most dangerous indoor air pollutants is carbon monoxide (CO). CO can be lethal, but perhaps more important, many people suffer ill health from chronic, often undetected exposure to low levels of this gas, resulting in fatigue, headache, dizziness, nausea, and vomiting. Another dangerous pollutant is volatile organic compounds (VOCs), which come from sources including building products, cleaning agents, and paints. One VOC, formaldehyde, can act as an irritant to the conjunctiva and upper and lower respiratory tract. Formaldehyde is also known to cause nasal cancer in test animals.
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PMID:A healthy home environment? 1037 13

Transcranial Doppler (TCD) recording was used to evaluate the mean flow velocity (MFV) and cerebrovascular reactivity to CO2 in 21 migraineurs during the interictal phase. Nine were affected by migraine with aura (MwA) and 12 by migraine without aura (MwoA). During each session the middle cerebral artery (MCA) flow velocity was examined in basal conditions, in hypocapnia after a 3-min period of hyperventilation, in basal conditions a second time, and in hypercapnia after breath-holding. The same procedure was followed in a group of 21 age- and sex-matched volunteers. Recordings were performed before (T1), during (T2), and after (T3) prophylactic treatment with flunarizine (10 mg/day for 2 months) to assess the possible effect of this drug on cerebral hemodynamics. In basal condition, increased MFV values were found in both MwA and MwoA patients. In MwA patients the reactivity index (RI) to hypocapnia was significantly increased in T1 (p < 0.05). This abnormal cerebrovascular reactivity disappeared during flunarizine treatment (T2) and in the post-therapy period (T3).
Cephalalgia 1999 Jun
PMID:Transcranial Doppler evaluation of cerebral hemodynamics in migraineurs during prophylactic treatment with flunarizine. 1040 64


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