Judith A. Leech

Air pollution and emergency department visits for cardiac and respiratory conditions: a multi-city time-series analysis

BackgroundRelatively few studies have been conducted of the association between air pollution and emergency department (ED) visits, and most of these have been based on a small number of visits, for a limited number of health conditions and pollutants, and only daily measures of exposure and response.MethodsA time-series analysis was conducted on nearly 400,000 ED visits to 14 hospitals in seven Canadian cities during the 1990s and early 2000s. Associations were examined between carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), sulfur dioxide (SO2), and particulate matter (PM10 and PM2.5), and visits for angina/myocardial infarction, heart failure, dysrhythmia/conduction disturbance, asthma, chronic obstructive pulmonary disease (COPD), and respiratory infections. Daily and 3-hourly visit counts were modeled as quasi-Poisson and analyses controlled for effects of temporal cycles, weather, day of week and holidays.Results24-hour average concentrations of CO and NO2 lag 0 days exhibited the most consistent associations with cardiac conditions (2.1% (95% CI, 0.0–4.2%) and 2.6% (95% CI, 0.2–5.0%) increase in visits for myocardial infarction/angina per 0.7 ppm CO and 18.4 ppb NO2 respectively; 3.8% (95% CI, 0.7–6.9%) and 4.7% (95% CI, 1.2–8.4%) increase in visits for heart failure). Ozone (lag 2 days) was most consistently associated with respiratory visits (3.2% (95% CI, 0.3–6.2%), and 3.7% (95% CI, -0.5–7.9%) increases in asthma and COPD visits respectively per 18.4 ppb). Associations tended to be of greater magnitude during the warm season (April – September). In particular, the associations of PM10 and PM2.5with asthma visits were respectively nearly three- and over fourfold larger vs. all year analyses (14.4% increase in visits, 95% CI, 0.2–30.7, per 20.6 μg/m3 PM10 and 7.6% increase in visits, 95% CI, 5.1–10.1, per 8.2 μg/m3 PM2.5). No consistent associations were observed between three hour average pollutant concentrations and same-day three hour averages of ED visits.ConclusionIn this large multicenter analysis, daily average concentrations of CO and NO2 exhibited the most consistent associations with ED visits for cardiac conditions, while ozone exhibited the most consistent associations with visits for respiratory conditions. PM10 and PM2.5 were strongly associated with asthma visits during the warm season.

Quality-of-life following thoracotomy for lung cancer

Contrary to the issues of perioperative morbidity and survival following surgery for lung cancer, little attention has been given to quality-of-life. To address this, quality-of-life was assessed preoperatively and 1, 3, 6 and 9 months postoperatively in a cohort of 117 consecutive subjects who underwent thoracotomy with a certain or presumptive diagnosis of lung cancer. Those with cancer (n = 91) confirmed at thoracotomy were contrasted to those without (n = 26). Moderate to severe dyspnea, reported in 14% preoperatively, increased to 34% at 1 and 3 months (p < 0.005) but returned to approximately 10% at 6 and 9 months. Similarly, activities of daily living were impaired in 11% preoperatively; this disability increased to 21% at 1 month (p < 0.005), and returned to baseline at 6 and 9 months. Those with cancer compared to those without a postoperative diagnosis of cancer had similar quality-of-life preoperatively but deteriorated more in the postoperative period. This study demonstrates that important deterioration in quality-of-life occurs during the first 3 months postoperatively in those with a final diagnosis of cancer but improvement back to baseline can be expected thereafter.

Effects of Short-Term Continuous Positive Airway Pressure on Myocardial Sympathetic Nerve Function and Energetics in Patients With Heart Failure and Obstructive Sleep Apnea A Randomized Study

Background— Heart failure with reduced ejection fraction and obstructive sleep apnea (OSA), 2 states of increased metabolic demand and sympathetic nervous system activation, often coexist. Continuous positive airway pressure (CPAP), which alleviates OSA, can improve ventricular function. It is unknown whether this is due to altered oxidative metabolism or presynaptic sympathetic nerve function. We hypothesized that short-term (6–8 weeks) CPAP in patients with OSA and heart failure with reduced ejection fraction would improve myocardial sympathetic nerve function and energetics. Methods and Results— Forty-five patients with OSA and heart failure with reduced ejection fraction (left ventricular ejection fraction 35.8±9.7% [mean±SD]) were evaluated with the use of echocardiography and 11C-acetate and 11C-hydroxyephedrine positron emission tomography before and ≈6 to 8 weeks after randomization to receive short-term CPAP (n=22) or no CPAP (n=23). Work metabolic index, an estimate of myocardial efficiency, was calculated as follows: (stroke volume index×heart rate×systolic blood pressure÷Kmono), where Kmono is the monoexponential function fit to the myocardial 11C-acetate time-activity data, reflecting oxidative metabolism. Presynaptic sympathetic nerve function was measured with the use of the 11C-hydroxyephedrine retention index. CPAP significantly increased hydroxyephedrine retention versus no CPAP (&Dgr;retention: +0.012 [0.002, 0.021] versus −0.006 [−0.013, 0.005] min−1; P=0.003). There was no significant change in work metabolic index between groups. However, in those with more severe OSA (apnea-hypopnea index >20 events per hour), CPAP significantly increased both work metabolic index and systolic blood pressure (P<0.05). Conclusions— In patients with heart failure with reduced ejection fraction and OSA, short-term CPAP increased hydroxyephedrine retention, indicating improved myocardial sympathetic nerve function, but overall did not affect energetics. In those with more severe OSA, CPAP may improve cardiac efficiency. Further outcome-based investigation of the consequences of CPAP is warranted. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00756366.

Acute and chronic effects of continuous positive airway pressure therapy on left ventricular systolic and diastolic function in patients with obstructive sleep apnea and congestive heart failure

BACKGROUND Obstructive sleep apnea (OSA) may contribute to the pathogenesis of congestive heart failure (CHF). Nocturnal continuous positive airway pressure (CPAP) therapy can alleviate OSA and may have a role in the treatment of CHF patients. OBJECTIVES To investigate the acute and chronic effects of CPAP therapy on left ventricular systolic function, diastolic function and filling pressures in CHF patients with OSA. METHODS Twelve patients with stable CHF (New York Heart Association II or III, radionuclide ejection fraction lower than 40%) underwent overnight polysomnography to detect OSA. In patients with OSA (n=7), echocardiography was performed at baseline (awake, before and during acute CPAP administration) and after 6.9+/-3.3 weeks of nocturnal CPAP therapy. Patients without OSA (n=5) did not receive CPAP therapy, but underwent a baseline and follow-up echocardiogram. RESULTS In CHF patients with OSA, acute CPAP administration resulted in a decrease in stroke volume (44+/-15 mL versus 50+/-14 mL, P=0.002) and left ventricular ejection fraction ([LVEF] 34.8+/-5.0% versus 38.4+/-3.3%, P=0.006) compared with baseline, but no change in diastolic function or filling pressures (peak early diastolic mitral annular velocity [Ea]: 6.0+/-1.6 cm/s versus 6.3+/-1.6 cm/s, P not significant; peak early filling velocity to peak late filling velocity [E/A] ratio: 1.05+/-0.74 versus 1.00+/-0.67, P not significant; E/Ea ratio: 10.9+/-4.1 versus 11.3+/-4.1, P not significant). In contrast, chronic CPAP therapy resulted in a trend to an increase in stroke volume (59+/-19 mL versus 50+/-14 mL, P=0.07) and a significant increase in LVEF (43.4+/-4.8% versus 38.4+/-3.3%, P=0.01) compared with baseline, but no change in diastolic function or filling pressures (Ea: 6.2+/-1.2 cm/s versus 6.3+/-1.6 cm/s, P not significant; E/A ratio: 1.13+/-0.61 versus 1.00+/-0.67, P not significant; E/Ea ratio: 12.1+/-2.7 versus 11.3+/-4.1, P not significant). There was no change in left ventricular systolic function, diastolic function or filling pressures at follow-up in CHF patients without OSA. CONCLUSIONS Acute CPAP administration decreased stroke volume and LVEF in stable CHF patients with OSA. In contrast, chronic CPAP therapy for seven weeks improved left ventricular systolic function, but did not affect diastolic function or filling pressures. The potential clinical implications of the discrepant effects of CPAP therapy on left ventricular systolic and diastolic function in CHF patients with OSA warrant further study.

The association between personal care products and lung function.

PURPOSE Chemical exposures are important determinants of respiratory health. The objective of the present study was to determine the association between the use of personal care products, which may contain respirable components, and lung function. METHODS Using questionnaire and spirometry data collected during the Canadian Health Measures population survey, the association was tested between 1-second forced expiratory volume (FEV(l)) and forced vital capacity (FVC) expressed as a percentage of predicted, and the frequency of use of personal care products categorized as eye makeup, fragrances, hairstyle products, lipstick, and scented body products. RESULTS Five thousand sixteen of the 5604 participants in the survey reported using at least one personal care product in the past 3 months. Among men and women, an interquartile increase in hairstyle products was associated with an approximate 2% decrease in both FEV(1) and FVC (P < .05). Among women, each product category was associated with a significant decrease in lung function with the largest observed effect being a 4.08% (95% confidence interval, 7.71-0.45) decrease in FVC associated with an interquartile range increase in the frequency of use of scented body products. CONCLUSIONS This study provides data suggesting that using personal care products may have a small adverse effect on lung function. Further research is warranted to investigate this possibility.

Changes in sleep duration and recreational screen time among Canadians, 1998–2010

It is commonly claimed that sleep duration has declined in recent years – over a period coinciding with a marked increase in personal electronics and communications use. The aim of this study was to assess change in sleep duration among Canadians from 1998 to 2010, and examine any associations with non‐work‐related screen time. The analysis uses population‐representative data from Statistics Canadas General Social Survey cycles of 1998 and 2010; the respective samples numbered 10 749 and 15 390 individuals. Response rates were 80% in 1998 and 55% in 2010. Respondents were aged 15 years and older, residing in private households in the 10 Canadian provinces. The General Social Survey is administered by computer‐assisted telephone interviewing. Data on sleep duration (excluding naps outside essential sleep time) and recreational screen time were obtained using a 24‐h time‐use diary. Survey weights were applied to adjust for non‐response and non‐landline households. Frequencies (respondent characteristics) and averages (time‐use variables) were estimated by age group and sex. Sleep duration was examined by weighted quartile of screen time. Confidence intervals (95%) were calculated around estimates. Average sleep duration increased from 8.1 h in 1998 to 8.3 h in 2010. Average screen time increased from 140 min in 1998 to 154 min in 2010. Sleep duration and screen time were positively related in both years. The percentage of people averaging less than 6 h sleep decreased from 9.6% in 1998 to 8.6% in 2010. Between 1998 and 2010, increases in screen time did not occur at the expense of sleep duration.