Meteorological influences on myocardial infarction in the metropolitan area of Milan

Ionisers for chronic asthma

BACKGROUND

Previous reports have shown that ion content in the air may have an effect on respiratory function. Results from studies which test the efficacy of air ionisers to reduce asthma symptoms are often inconclusive and their use as a treatment for asthma remains debatable.

OBJECTIVES

We conducted a systematic review of the available evidence to determine the effectiveness of positive and negative ion generators in people with asthma.

SEARCH METHODS

We searched the Cochrane Airways Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL) as well as the alternative medicine database AMED. Searches were current as of June 2012.

SELECTION CRITERIA

Randomised controlled trials (parallel or crossover design studies) comparing ionisers with dummy ionisers (being negative or positive ion emitters), in children or adults with chronic asthma.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed titles and abstracts of studies and assessed trial quality. Study quality was determined using two methods:The Cochrane approach to allocation concealment and the five point Jadad scale.

MAIN RESULTS

Six studies were selected for inclusion (106 participants). No results were combined as the studies were all of a crossover design.EFFECTS OF NEGATIVE ION GENERATORS (five studies) No study reported a significant difference in lung function between ionised and control air (morning Peak expiratory flow (PEF) - three studies; forced expiratory flow in one second (FEV1) - one study). There were no significant differences in symptoms or beta-2 agonist usage between ionised and control air in three studies.EFFECTS OF POSITIVE ION GENERATORS (one study) This study demonstrated that although positively ionised air was associated with a larger fall in FEV1 with exercise, this did not reach statistical significance. Baseline FEV1 was not demonstrated to be significantly different between treatment groups.

AUTHORS' CONCLUSIONS

Based on the evidence currently available from randomised controlled trials, a recommendation cannot be given for the use of room air ionisers to reduce symptoms in patients with chronic asthma.

Acute coronary syndromes related to bio-climate in a Mediterranean area. The case of Ierapetra, Crete Island, Greece

The occurrence of non-fatal acute coronary syndromes (ACS) is examined in relation with the local bioclimatic conditions in the Ierapetra area, in the southernmost part of Crete Island, Greece, during the period 2004-2007. Daily ACS counts and corresponding meteorological parameters, such as maximum and minimum air temperature, relative humidity, wind speed and cloudiness, were analyzed. Besides, the daily values of the human thermal index, physiologically equivalent temperature (PET) was evaluated. Pearson's χ(2) test and generalized linear models (GLM) with Poisson distribution were applied. The ACS syndromes present a multiple variation within the year, with the primary maximum in August and the secondary in May, while relative high ACS frequencies exist in early winter time. The impact of the weather variability on the ACS incidence is not statistically significant (C.L. 95%).

Impact of weather and climate on the incidence of acute coronary syndromes

BACKGROUND

First investigations of the interactions between weather and the incidence of acute myocardial infarctions date back to 1938. The early observation of a higher incidence of myocardial infarctions in the cold season could be confirmed in very different geographical regions and cohorts. While the influence of seasonal variations on the incidence of myocardial infarctions has been extensively documented, the impact of individual meteorological parameters on the disease has so far not been investigated systematically. Hence the present study intended to assess the impact of the essential variables of weather and climate on the incidence of myocardial infarctions.

METHODS

The daily incidence of myocardial infarctions was calculated from a national hospitalization survey. The hourly weather and climate data were provided by the database of the national weather forecast. The epidemiological and meteorological data were correlated by multivariate analysis based on a generalized linear model assuming a log-link-function and a Poisson distribution.

RESULTS

High ambient pressure, high pressure gradients, and heavy wind activity were associated with an increase in the incidence of the totally 6560 hospitalizations for myocardial infarction irrespective of the geographical region. Snow- and rainfall had inconsistent effects. Temperature, Foehn, and lightning showed no statistically significant impact.

CONCLUSIONS

Ambient pressure, pressure gradient, and wind activity had a statistical impact on the incidence of myocardial infarctions in Switzerland from 1990 to 1994. To establish a cause-and-effect relationship more data are needed on the interaction between the pathophysiological mechanisms of the acute coronary syndrome and weather and climate variables.

Relationships between weather and myocardial infarction: a biometeorological approach

OBJECTIVES

To calculate threshold values of weather discomfort which increase the risk of hospital admissions for myocardial infarction in winter and summer.

BACKGROUND

Notwithstanding heat waves were reported to acutely increase hospital admissions for cardiovascular diseases, large surveys failed to reveal any increase of event rates with increasing air temperature. However, the assessment of air temperature does not allow evaluation of the actual discomfort perception caused by the combination of different meteorological parameters.

METHODS

Hospital admissions for myocardial infarction for the period 1998-2002 in Florence, Italy, were considered. The percentages of variation of daily event rates according to daily mean air temperature variations were preliminary derived by using a regression analysis. An alternative biometeorological approach, considering the Apparent Temperature Index (ATI) in summer, and the New U.S./Canada Wind Chill Temperature Index (NWCTI) in winter, which combine air temperature, relative humidity and wind velocity, was then used.

RESULTS

The traditional approach showed that daily event rates significantly increased with daily mean air temperature decrease (10 degrees C decrease were associated with 19% increase in daily event rates for people older than 65 years), but failed to show any negative effect caused by hot climatic conditions. Conversely the biometeorological approach allowed to show that at least 9 h per day of severe discomfort caused by hot conditions significantly increased the rate of admission (P<0.01).

CONCLUSIONS

This approach might be useful for the development of an operative weather watch/warning system for population and for hospital professional care.

Ionisers for chronic asthma

BACKGROUND

Previous reports have shown that ion content in the air may have an effect on respiratory function. Results from studies which test the efficacy of air ionisers to reduce asthma symptoms are often inconclusive and their use as a treatment for asthma remains debatable.

OBJECTIVES

We conducted a systematic review of the available evidence to determine the effectiveness of positive and negative ion generators in people with asthma.

SEARCH STRATEGY

We searched the Cochrane Airways Group Asthma trials register (January 1966 to March 2003), Cochrane Central Register of Controlled Trials (Cochrane Library issue 2, 2003) as well as The Alternative Medicine Database AMED (1985 to March 2003).

SELECTION CRITERIA

Randomised controlled trials (parallel or crossover design studies) comparing ionisers with dummy ionisers (being negative or positive ion emitters), in children or adults with chronic asthma.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed titles and abstracts of studies and assessed trial quality. Study quality was determined using two methods:The Cochrane approach to allocation concealment and the five point Jadad scale.

MAIN RESULTS

Six studies were selected for inclusion (106 participants). No results were combined as the studies were all of a crossover design. EFFECTS OF NEGATIVE ION GENERATORS (five studies)No study reported a significant difference in lung function between ionised and control air (morning Peak expiratory flow (PEF) - three studies; forced expiratory flow in one second (FEV1) - one study). There were no significant differences in symptoms or beta-2 agonist usage between ionised and control air in three studies. EFFECTS OF POSITIVE ION GENERATORS (one study)This study demonstrated that although positively ionised air was associated with a larger fall in FEV1 with exercise, this did not reach statistical significance. Baseline FEV1 was not demonstrated to be significantly different between treatment groups.

REVIEWER'S CONCLUSIONS

Based on the evidence currently available from randomised controlled trials, a recommendation cannot be given for the use of room air ionisers to reduce symptoms in patients with chronic asthma.

Weather and the risk of sudden infant death syndrome: the effect of wind

STUDY OBJECTIVE

To examine and identify relations between sudden infant death syndrome (SIDS) and wind, particularly the föhn wind, in Christchurch, New Zealand.

DESIGN

A retrospective epidemiological study combining details of regional hourly meteorological variables and reported SIDS cases.

SETTING

Christchurch, New Zealand, between 1968 and 1997 inclusively.

PARTICIPANTS

All 646 infants reported as dying from SIDS within the greater Christchurch region.

MAIN RESULTS

Analysis of 1968-1989 data revealed nine wind variables significantly related to SIDS. When compared with corresponding variables calculated over the 1990-1997 period, only the northerly wind on the day of death and the southerly wind three days before a SIDS death had estimated associations with similar effect size and sign. However, both these variables had confidence intervals that included unity.

CONCLUSIONS

No evidence was found to suspect that föhn winds influenced SIDS occurrence. The relations identified between SIDS incidence and wind, after controlling for the effects of temperature and trend, were tenuous and relatively small. More data are necessary to substantiate whether northerly winds on the day of death or southerly winds occurring three days before a death are truly associated with SIDS. It seems that wind has little, if any effect on SIDS incidence in Christchurch.

Asthma exacerbations during Santa Ana winds in southern California

This study investigated the relationship between Santa Ana wind conditions and visits for asthma at a southern California emergency department. Visits to the emergency department for asthma were analyzed retrospectively to determine whether the incidence increased during Santa Ana wind conditions. These northeasterly winds are common during fall and winter in southern California and belong to a class known as Foehn winds. They are characterized by gusty winds, decreased relative humidity, warm temperatures, and decreased levels of airborne pollutants. During a 4-year period, we noted that emergency department visits for asthma increased (3.12 vs. 2.16 visits per day, P < 0.0001) during SantaAna winds compared with other weather conditions. Asthmatics presenting during Santa Ana winds appeared to be more ill, as judged by higher admission rates (21.9 vs. 18.7%, P < 0.05). These winds were also associated with reduced particulate matter (PM10) counts (P < 0.0001). Although the magnitude of the increase in emergency department visits was small, it occurred at a time when typical inciters of respiratory disease should be minimal. An as yet unidentified factor associated with these winds may be a stimulant for some asthmatics. Similar wind patterns in other localities might affect respiratory disease as well.

Meteorological factors and the time of onset of chest pain in acute myocardial infarction

Analysis of the time of onset of chest pain in 2254 patients with a myocardial infarction admitted to a coronary care unit in Leicester during a 10-year period shows an association with temperature and humidity. During both the most cold and humid times of the year, the relationship is a strong one. A generalized linear model with a log link was used to fit the data and the backward elimination selection procedure suggested a humid, cold day might help to trigger the occurrence of myocardial infarction. In addition, cold weather was found to have a stronger effect on the male population while those men aged between 50 and 70 years were more sensitive to the effect of high humidity.

Sleeping hours: a relatively protected period for impending myocardial infarction

We have retrospectively investigated the time of the onset of acute myocardial infarction in 2046 patients admitted to six coronary care units in a two-year period. A significantly reduced number of patients (P less than 0.01) showed the beginning of acute myocardial infarction during the 0 to 6 a.m. period, while, during the remaining periods, no difference in frequency distribution was observed. Our results suggest that an impending myocardial infarction is more likely to occur at certain times of the day than others, suggesting a period of relative protection from onset.