Learner Driver Experience and Teenagers' Crash Risk During the First Year of Independent Driving

IMPORTANCE

One mechanism for teenagers' elevated crash risk during independent driving may be inadequate learner driving experience.

OBJECTIVE

To determine how learner driver experience was associated with crash risk during the first year of independent driving.

DESIGN, SETTING, AND PARTICIPANTS

Youth aged 15.5 to 16.1 years at recruitment were eligible to participate. Participants' vehicles were instrumented with sensors, and driving was recorded during the learner period through 1 year of independent driving. Data were collected from January 2011 through August 2014 in southwestern Virginia.

EXPOSURES

The amount, consistency and variety of practice, driving errors, and kinematic risky driving (KRD) rates during the learner period were recorded. Surveys, including one on sensation-seeking personality traits, were assessed at baseline.

MAIN OUTCOMES AND MEASURES

Cox proportional hazard regressions examined associations between individual characteristics and learner driving experience with driving time to first crash and all crashes in the first year of independent driving. So that hazard ratios (HRs) can be directly comparable, units of measurement were standardized to the interquartile range.

RESULTS

Of 298 individuals who responded to recruitment, 90 fulfilled the criteria and 82 completed the study (of whom 75 were white [91%] and 44 were girls [54%]). Teenage participants drove a mean (SD) of 1259.2 (939.7) miles over 89 days during the learner period. There were 49 property-damage crashes and/or police-reportable crashes during independent driving. Factors associated with driving time to first crash included higher sensation-seeking personality scale scores (HR, 1.67 [95% CI, 1.08-2.57] per 0.75-unit increase), learner driving KRD rates (HR, 1.27 [95% CI, 1.12-1.43] per 9.24-unit increase), and learner driving errors (HR, 0.44 [95% CI, 0.22-0.86] per increase of 6.48 errors). Similar results were obtained for all crashes in the first year, with the addition of consistency of learner driving practice (HR, 0.61 [95% CI, 0.38-0.99] per 0.23-unit increase).

CONCLUSIONS AND RELEVANCE

Individual characteristics and learner driving experiences were associated with crash risk during independent driving. As expected, there was an association between sensation seeking and crashes. Elevated KRD rates during the learner period may reflect risky driving behavior among novices or tolerance to abrupt maneuvers by parents who supervise driving. Consistent practice throughout the learner period could reduce teenage crash risk, which is supported by learning theories indicating distributed practice is effective for developing expertise. Errors during practice may constitute learning events that reinforce safer driving. Physicians could encourage parents to provide opportunities for regular practice driving and monitor their teenager's KRD rates during the learner period using in-vehicle or smartphone-based technology.

Long-Term Outcome after Prolonged Mechanical Ventilation. A Long-Term Acute-Care Hospital Study

Rationale: Patients managed at a long-term acute-care hospital (LTACH) for weaning from prolonged mechanical ventilation are at risk for profound muscle weakness and disability. Objectives: To investigate effects of prolonged ventilation on survival, muscle function, and its impact on quality of life at 6 and 12 months after LTACH discharge. Methods: This was a prospective, longitudinal study conducted in 315 patients being weaned from prolonged ventilation at an LTACH. Measurements and Main Results: At discharge, 53.7% of patients were detached from the ventilator and 1-year survival was 66.9%. On enrollment, maximum inspiratory pressure (Pi_max) was 41.3 (95% confidence interval, 39.4-43.2) cm H₂O (53.1% predicted), whereas handgrip strength was 16.4 (95% confidence interval, 14.4-18.7) kPa (21.5% predicted). At discharge, Pi_max did not change, whereas handgrip strength increased by 34.8% (P < 0.001). Between discharge and 6 months, handgrip strength increased 6.2 times more than did Pi_max. Between discharge and 6 months, Katz activities-of-daily-living summary score improved by 64.4%; improvement in Katz summary score was related to improvement in handgrip strength (r = -0.51; P < 0.001). By 12 months, physical summary score and mental summary score of 36-item Short-Form Survey returned to preillness values. When asked, 84.7% of survivors indicated willingness to undergo mechanical ventilation again. Conclusions: Among patients receiving prolonged mechanical ventilation at an LTACH, 53.7% were detached from the ventilator at discharge and 1-year survival was 66.9%. Respiratory strength was well maintained, whereas peripheral strength was severely impaired throughout hospitalization. Six months after discharge, improvement in muscle function enabled patients to perform daily activities, and 84.7% indicated willingness to undergo mechanical ventilation again.

Effect of pressure support vs unassisted breathing through a tracheostomy collar on weaning duration in patients requiring prolonged mechanical ventilation: a randomized trial

IMPORTANCE

Patients requiring prolonged mechanical ventilation (>21 days) are commonly weaned at long-term acute care hospitals (LTACHs). The most effective method of weaning such patients has not been investigated.

OBJECTIVE

To compare weaning duration with pressure support vs unassisted breathing through a tracheostomy collar in patients transferred to an LTACH for weaning from prolonged ventilation.

DESIGN, SETTING, AND PARTICIPANTS

Between 2000 and 2010, a randomized study was conducted in tracheotomized patients transferred to a single LTACH for weaning from prolonged ventilation. Of 500 patients who underwent a 5-day screening procedure, 316 did not tolerate the procedure and were randomly assigned to receive weaning with pressure support (n = 155) or a tracheostomy collar (n = 161). Survival at 6- and 12-month time points was also determined.

MAIN OUTCOME MEASURE

Primary outcome was weaning duration. Secondary outcome was survival at 6 and 12 months after enrollment.

RESULTS

Of 316 patients, 4 were withdrawn and not included in analysis. Of 152 patients in the pressure-support group, 68 (44.7%) were weaned; 22 (14.5%) died. Of 160 patients in the tracheostomy collar group, 85 (53.1%) were weaned; 16 (10.0%) died. Median weaning time was shorter with tracheostomy collar use (15 days; interquartile range [IQR], 8-25) than with pressure support (19 days; IQR, 12-31), P = .004. The hazard ratio (HR) for successful weaning rate was higher with tracheostomy collar use than with pressure support (HR, 1.43; 95% CI, 1.03-1.98; P = .033) after adjusting for baseline clinical covariates. Use of the tracheostomy collar achieved faster weaning than did pressure support among patients who did not tolerate the screening procedure between 12 and 120 hours (HR, 3.33; 95% CI, 1.44-7.70; P = .005), whereas weaning time was equivalent with the 2 methods in patients who did not tolerate the screening procedure within 0 to 12 hours. Mortality was equivalent in the pressure-support and tracheostomy collar groups at 6 months (55.92% vs 51.25%; 4.67% difference, 95% CI, -6.4% to 15.7%) and at 12 months (66.45% vs 60.00%; 6.45% difference, 95% CI, -4.2% to 17.1%).

CONCLUSION AND RELEVANCE

Among patients requiring prolonged mechanical ventilation and treated at a single long-term care facility, unassisted breathing through a tracheostomy, compared with pressure support, resulted in shorter median weaning time, although weaning mode had no effect on survival at 6 and 12 months.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01541462.

Central sleep apnea induced by acute ingestion of opioids

OBJECTIVES

Three cases are presented in which patients were using opioids as required for nonmalignant pain management and significant central sleep apnea developed. Patients in the first two cases had no evidence of sleep-related breathing disorders on polysomnography until they ingested an opioid for treatment of chronic pain during the night and severe central sleep apnea developed. The patient in our third case had established obstructive sleep apnea but experienced a significant number of central events after the ingestion of an opioid analgesic, leading to worsening severity of his underlying sleep-related breathing disorder.

CONCLUSION

The short-term ingestion of opioid analgesics can precipitate central sleep apnea in patients with chronic pain receiving long-term opiate therapy who otherwise show no evidence of central sleep apnea and have no cardiac or neurologic disease that would predispose them to central sleep apnea.

High-resolution CT findings in patients with pulmonary tuberculosis: correlation with the degree of smear positivity

BACKGROUND

There are data about the relationship between morphologic findings on high-resolution computed tomography (HRCT) and the number of acid-fast bacilli (AFB) on sputum smears in patients with pulmonary tuberculosis (PTB). It was also shown that existence of cavities and airspace consolidation might be related to smear positivity in PTB patients. However, there is no study suggesting a relationship between AFB on sputum smears and radiologic extent of disease based on HRCT findings.

AIM

In this study, we investigated a relationship between the degree of smear positivity and radiologic extent of disease based on HRCT findings and, the degree of smear positivity and different pulmonary parenchymal changes on HRCTs of the PTB patients.

METHODS

Sixty-one male patients with PTB (mean age: 22+/-3.2) were included into the study. HRCT images were assessed for patterns, distribution, and profusion of pulmonary abnormalities. Dividing the lungs into 3 zones, profusion of abnormalities was assessed. A profusion score was given. Patients were divided as smear positive and smear negative and compared for the scores of HRCT findings. Smear-positive patients were divided into 4 groups as per grading of the sputum AFB smear: group I (sputum 1+), group II (sputum 2+), group III (sputum 3+), and group IV (sputum 4+). Correlations were investigated between the degree of smear positivity and the scores of HRCT findings.

RESULTS

A significant correlation between radiologic extent of the disease based on HRCT and the degree of smear positivity was found (r=0.63, P=0.0001). There were also significant correlations between the degree of smear positivity and the scores of different HRCT findings. Nodule, cavity, and bronchial lesions are the most important contributors of the predictive properties of the total score. There was significant differences for the scores of HRCT findings between smear-positive and smear-negative patients.

CONCLUSIONS

Our study suggests that radiologic extent of disease based on HRCT findings in patients with PTB correlated with the degree of smear positivity. Different HRCT findings such as nodule, cavitation, ground-glass opacity, consolidation, and bronchial lesion are significantly associated with smear-positive PTB. Particularly, nodules, cavities, and bronchial lesions might be predictors of smear positivity in patients with PTB. This study also suggests that the thickness of cavity wall and the distance of cavity from central airways might be related to the degree of smear positivity.

Airway bacterial concentrations and exacerbations of chronic obstructive pulmonary disease

RATIONALE

Increased bacterial concentration (load) in the lower airways and new bacterial strain acquisition have been posited as mechanisms for chronic obstructive pulmonary disease (COPD) exacerbations. Bacterial concentrations are higher during exacerbation than during stable disease; however, these studies are cross sectional and devoid of strain typing.

OBJECTIVES

To determine if the increased bacterial concentrations function as a separate mechanism for exacerbation induction independent of new strain acquisition.

METHODS

In a prospective, longitudinal cohort of patients with COPD, the relationship between exacerbation occurrence, sputum bacterial concentrations, and new strain acquisition was examined.

MEASUREMENTS AND MAIN RESULTS

Clinical information, quantitative sputum cultures, and molecular typing of potential bacterial pathogen isolates. Over 81 months, 104 subjects completed 3,009 clinic visits, 560 (19.6%) during exacerbations and 2,449 (80.4%) during stable disease. Among preexisting strains, sputum concentrations of Nontypeable Haemophilus influenzae and Haemophilus haemolyticus were not different in exacerbation versus stable disease. Moraxella catarrhalis (stable, 10(8.38 +/- 0.13) [mean +/- SEM] vs. exacerbation, 10(7.78 +/- 0.26); p = 0.02) and Streptococcus pneumoniae (stable, 10(8.42 +/- 0.21) vs. exacerbation, 10(7.76 +/- 0.52); p = 0.07) concentrations were lower during exacerbations compared with stable periods. Concentrations of new strains of H. influenzae (stable, 10(7.28 +/- 0.15) vs. exacerbation, 10(7.76 +/- 0.17); p = 0.04) and M. catarrhalis (stable, 10(7.85 +/- 0.15) vs. exacerbation, 10(8.37 +/- 0.14); p = 0.02), were increased during exacerbations; however, the differences were small.

CONCLUSIONS

Change in bacterial load is unlikely to be an important mechanism for exacerbations. Better understanding of the host-pathogen interaction, rather than enumerating bacteria in respiratory samples, is required to provide new insights into bacterial infection in COPD.

Simulated obesity-related changes in lung volume increases airway responsiveness in lean, nonasthmatic subjects

STUDY OBJECTIVE

To determine if obesity-related changes in lung volume might contribute to airway reactivity, we investigated the effects of simulated mild obesity-related lung volume reductions on airway responsiveness in lean, nonasthmatic subjects.

PARTICIPANTS AND METHODS

We simulated the lung volume reductions of class 1 obesity in eight lean, nonasthmatic subjects by externally mass loading the chest wall and abdomen, and shifting blood volume into the lung with lower limb compression (LLC). Airway responsiveness was assessed by measuring FEV(1) before and after methacholine challenge tests (1, 2.5, 5, 10, and 25 mg/mL) with the following: (1) no intervention (control); (2) external chest loading (CL); (3) LLC; and (4) CL and LLC (COMB) on separate days. Lung function was measured before and after CL, LLC, and COMB were applied.

RESULTS

The application of CL, LLC, and COMB decreased expiratory reserve volume, functional residual capacity, and total lung capacity compared with baseline. FVC and FEV(1) decreased significantly with CL and COMB, while FEV(1)/FVC did not change compared to baseline. The maximal response to the methacholine challenge increased with CL, LLC, and COMB, with a mean maximal fall of FEV(1) of 9%, 11%, and 18%, respectively, compared to a 6% fall with control.

CONCLUSIONS

We conclude that decreases in lung volume increase airway responsiveness and may account for the increased propensity for increased airway responsiveness in the obese.

Pulmonary function and abdominal adiposity in the general population

BACKGROUND

The prevalence of obesity is increasing, and there is evidence that obesity, in particular abdominal obesity as a marker of insulin resistance, is negatively associated with pulmonary function. The mechanism for this association and the best marker of abdominal adiposity in relation to pulmonary function is not known.

STUDY OBJECTIVE

We assessed the association between pulmonary function and weight, body mass index (BMI), waist circumference, waist/hip ratio, and abdominal height as markers of adiposity and body fat distribution. We used multiple linear regression to analyze the association of pulmonary function (ie, FEV(1) and FVC) [with maneuvers performed in the sitting position] with overall adiposity markers (ie, weight and BMI) and abdominal adiposity markers, stratified by gender, and adjusted for height, age, race, smoking, and other covariates.

SETTING AND PARTICIPANTS

A random sample of individuals (n = 2,153) from the general population living in western New York state, 35 to 79 years of age.

RESULTS

In women, abdominal height and waist circumference were negatively associated with FEV(1) percent predicted, while all five adiposity markers were negatively associated with FVC percent predicted. In men, all overall and abdominal adiposity markers were inversely associated with FEV(1) percent predicted and FVC percent predicted.

CONCLUSION

These results suggest that abdominal adiposity is a better predictor of pulmonary function than weight or BMI, and investigators should consider it when investigating the determinants of pulmonary function.

Brief report: Internal medicine residents', attendings', and nurses' perceptions of the night float system

BACKGROUND

Residency training programs use the night float system increasingly to meet the new resident work hour regulations.

OBJECTIVE

To assess and compare residents', attendings', and nurses' perceptions of the night float system.

DESIGN

A survey study.

PARTICIPANTS

One hundred and seven residents, 48 attendings, and 69 nurses in a university-based multicenter internal medicine residency program.

MEASUREMENTS

Perceived impact on patient care, resident training, and resident performance.

RESULTS

The overall response rate was 75%. In general, more residents than both attendings and nurses had positive opinions regarding the night float system, particularly in relation to patient care. Only a small proportion of residents and attendings thought positively about the night float's impact on training quality (29.9%; 18.2%), daily feedback (23.0%; 9.1%), and end of rotation evaluation (21.8%; 6.1%). Less than half of the nurses had positive perceptions of the night residents' performance in terms of promptness (40.9%), physical availability (38.6%), familiarity with the patients' cases, and management plans (15.9%), communication of management plans to nurses (36.4%), professional respect and trust (43.2%), and teamwork (45.5%).

CONCLUSIONS

Residents had more positive perceptions than attendings and nurses. Nurses, in particular, had negative perceptions of resident performance in the setting of the night float system.

Allopurinol improves endothelial function in sleep apnoea: a randomised controlled study

Increased oxidative stress in obstructive sleep apnoea is thought to contribute to endothelial dysfunction. The objective of this study was to test the hypothesis that inhibition of xanthine oxidase by allopurinol can improve endothelial function in patients with obstructive sleep apnoea. A randomised double-blind placebo-controlled crossover study was performed on 12 patients with moderate-to-severe obstructive sleep apnoea, comparing 300 mg allopurinol daily for 2 weeks with placebo. Endothelial function was assessed using hyperaemia-induced flow-mediated vasodilation (FMD) at baseline and following treatment. Plasma malondialdehyde levels were compared in order to assess significant changes in oxidative stress. Baseline FMD correlated significantly with the severity of sleep apnoea and the time spent with an arterial oxygen saturation of <90%. Allopurinol caused a significant increase in FMD compared to placebo (10.4+/-3.2 versus 7.4+/-2.8%, respectively). Plasma malondialdehyde levels were significantly reduced with allopurinol treatment (1.5+/-0.3 versus 1.2+/-0.3 micromol.L(-1)), consistent with reduced oxidative stress. Allopurinol improves endothelial dysfunction in patients with moderate-to-severe obstructive sleep apnoea. These observations suggest that xanthine oxidase contributes significantly to vasodilatory impairment.

Antioxidants, oxidative stress, and pulmonary function in individuals diagnosed with asthma or COPD

OBJECTIVE

The objective of this study was to investigate the association between antioxidant nutrients and markers of oxidative stress with pulmonary function in persons with chronic airflow limitation.

DESIGN

Cross-sectional study exploring the association of antioxidant nutrients and markers of oxidative stress with forced expiratory volume in the first second (FEV1%) and forced vital capacity (FVC%).

SETTING/SUBJECTS

The study data included 218 persons with chronic airflow limitation recruited randomly from the general population of Erie and Niagara counties, New York State, USA.

RESULTS

After adjustment for covariates, multiple linear regression analysis showed that serum beta-cryptoxanthin, lutein/zeaxanthin, and retinol, and dietary beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin, vitamin C, and lycopene were positively associated with FEV1% (P < 0.05, all associations). Serum vitamins beta-cryptoxanthin, lutein/zeaxanthin, and lycopene, and dietary beta-cryptoxanthin, beta-carotene, vitamin C, and lutein/zeaxanthin were positively associated with FVC% (P < 0.05, all associations). Erythrocytic glutathione was negatively associated with FEV1%, while plasma thiobarbituric acid-reactive substances (TBARS) were negatively associated with FVC% (P < 0.05).

CONCLUSION

These results support the hypothesis that an imbalance in antioxidant/oxidant status is associated with chronic airflow limitation, and that dietary habits and/or oxidative stress play contributing roles.

Oxidative stress and pulmonary function in the general population

Studies have shown increased oxidative stress in patients with chronic airflow limitation; however, the population-based evidence for the association of oxidative stress with pulmonary function is limited. The authors analyzed the association of plasma thiobarbituric acid-reactive substances (TBARS), glutathione, glutathione peroxidase, and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox)-equivalent antioxidant capacity with forced expiratory volume in 1 second and forced vital capacity using data collected from 1996 to 2000 in a general population sample from western New York State (n = 2,346). After adjustment for covariates including smoking status, lifetime pack-years of smoking, education, weight, and eosinophils, multivariate analysis showed an inverse association of TBARS with forced expiratory volume in 1 second and forced vital capacity as the percentage of the predicted value (FEV1% and FVC%, respectively), positive associations of glutathione peroxidase with FEV1% and FVC%, and an inverse association of glutathione with FEV1% in men (p < 0.05). The associations of TBARS and glutathione peroxidase with FVC% in men remained statistically significant after adjustment for serum carotenoid levels. There were no statistically significant associations of oxidative stress with pulmonary function in women. These results suggest that oxidative stress may be associated with airflow limitation in men, and that gender differences may exist in the relation of oxidative stress to pulmonary function.

Is being breastfed as an infant associated with adult pulmonary function?

OBJECTIVE

Breastfeeding reduces the risk of asthma and respiratory infections in infants. Since respiratory infections are associated with reduced pulmonary function in adolescents, pulmonary function impairment may be carried into adulthood. Our aim was to determine whether a history of having been breastfed as an infant is a determinant of adult pulmonary function.

METHODS

We analyzed data from a general population sample of residents of Erie and Niagara Counties between September 1995 and December 1999. We calculated forced expiratory volume in one second (FEV(1)) and forced vital capacity (FVC) prediction equations and used multiple linear regression models to study the association between having been breastfed as an infant and percentage predicted FEV(1) (FEV(1)%) and percentage predicted FVC (FVC%) after adjustment for covariates.

RESULTS

Of 2305 subjects, 62% reported having been breastfed. After controlling for age, gender, weight, smoking status, pack-years of smoking, eosinophil counts and dietary factors, there was no association between having been breastfed (yes/no) and FEV(1)% or FVC% (regression coefficients 0.0049, p = 0.46 and 0.0055, p = 0.43, respectively).

CONCLUSIONS

We did not find a strong or consistent association between having been breastfed as an infant and pulmonary function in adulthood.

Prevalence of Positional Sleep Apnea in Patients Undergoing Polysomnography

STUDY OBJECTIVES

The primary aim of this study was to determine the prevalence of positional obstructive sleep apnea using a functional definition. Positional sleep apnea was defined as a total apnea-hypopnea index (AHI) > or = 5 with a > 50% reduction in the AHI between the supine and nonsupine postures, and an AHI that normalizes (AHI < 5) in the nonsupine posture. A secondary aim was to determine if positional sleep apnea can be diagnosed accurately during a split-night study.

DESIGN

Retrospective chart review.

SETTING

Two sleep centers in Buffalo, NY, one a Veterans Affairs Western New York Healthcare System Sleep Center (VAWNY) and the other a freestanding ambulatory center (Associated Sleep Center [ASC]).

PATIENTS

Three hundred twenty-six patients from the VAWNY, including 57 patients who underwent a split-night study and 242 patients from the ASC who underwent polysomnography.

INTERVENTIONS

None.

MEASUREMENTS

Patient characteristics and sleep study results.

RESULTS

Positional sleep apnea was seen in 49 of 99 patients (49.5%) with mild sleep apnea (AHI, 5 to 15/h), 14 of 72 patients (19.4%) with moderate sleep apnea (AHI, 15 to 30/h), and 5 of 77 patients (6.5%) with severe sleep apnea (AHI > 30/h). Sufficient sleep (> 15 min) in both postures was not seen in 104 of 269 patients (38.7%) and 80 of 242 overnight studies (33.1%) at the VAWNY and ASC, respectively, and was not seen in 47 of 57 split-night studies (82.5%). The percentage of studies with insufficient sleep in both postures was significantly greater for split-night studies (p < 0.0001).

CONCLUSIONS

Positional sleep apnea is common particularly in patients with mild disease. Positional sleep apnea cannot usually be assessed during a split-night study.

Moraxella catarrhalis in chronic obstructive pulmonary disease: burden of disease and immune response

RATIONALE

Moraxella catarrhalis is frequently present in the sputum of adults with chronic obstructive pulmonary disease (COPD). Little is known about the role of M. catarrhalis in this common disease.

OBJECTIVE

To elucidate the burden of disease, the dynamics of carriage, and immune responses to M. catarrhalis in COPD.

METHODS

Prospective cohort study of 104 adults with COPD in an outpatient clinic at the Buffalo Veterans Affairs Medical Center.

MEASUREMENTS

Clinical information, sputum cultures, molecular typing of isolates, and immunoassays to measure antibodies to M. catarrhalis.

MAIN RESULTS

Over 81 months, 104 patients made 3,009 clinic visits, 560 during exacerbations. Molecular typing identified 120 episodes of acquisition and clearance of M. catarrhalis in 50 patients; 57 (47.5%) of the acquisitions were associated with clinical exacerbations. No instances of simultaneous acquisition of a new strain of another pathogen were observed. The duration of carriage of M. catarrhalis was shorter with exacerbations compared with asymptomatic colonization (median, 31.0 vs. 40.4 days; p = 0.01). Reacquisition of the same strain was rare. The intensity of the serum IgG response was greater after exacerbations than asymptomatic colonization (p = 0.009). Asymptomatic colonization was associated with a greater frequency of a sputum IgA response than exacerbation (p = 0.009).

CONCLUSIONS

M. catarrhalis likely causes approximately 10% of exacerbations of COPD, accounting for approximately 2 to 4 million episodes annually. The organism is cleared efficiently after a short duration of carriage. Patients develop strain-specific protection after clearance of M. catarrhalis from the respiratory tract.

Weaning prediction: esophageal pressure monitoring complements readiness testing

Several variables are recommended for identifying if a patient is ready for a trial of weaning from mechanical ventilation, but there is no agreement as to whether monitoring any variable during the trial enhances patient management. To determine whether repeated measurements of esophageal pressure throughout a trial are more reliable than measurements of esophageal pressure or frequency-to-VT ratio during the first minute of the trial, we studied 60 patients. A trend index that quantified esophageal pressure swings over time was more reliable than the first-minute measurements: sensitivity, 0.91, and specificity, 0.89. Area under receiver operating characteristic curve for trend index (0.94) was greater than for first-minute measurement of esophageal pressure (0.44, p < 0.05) and tended to be greater than that for frequency-to-VT ratio (0.78, p = 0.13). The likelihood ratio was highest for the trend index (8.2, p < 0.05). The advantage of the trend index may be related to the progressive increase in esophageal pressure throughout a failed weaning trial, whereas breathing pattern changed little after 2 minutes of spontaneous breathing. In conclusion, continuous monitoring of esophageal pressure swings during a spontaneous breathing trial provides additional guidance in patient management over tests used for deciding when to initiate weaning.

Systemic Administration of Serotonin 2A/2C Agonist Improves Upper Airway Stability in Zucker Rats

The effects of [+/-]-2,5-dimethoxy-4-iodoaminophentamine, a serotonin(2A/2C) receptor agonist, on pharyngeal airflow mechanics were examined in isoflurane-anesthetized lean and obese Zucker rats. The pharyngeal pressure associated with flow limitation, maximum inspiratory flow, oronasal resistance, genioglossus muscle activity, and arterial blood pressure (BP) were measured before and after the intravenous administration of the agonist. A robust activation of the genioglossus muscle in all lean and obese rats was associated with decreased upper airway (UA) collapsibility (p < 0.05), unchanged maximum flow, and increased oronasal resistance (p < 0.05) in both groups. The changes in UA mechanics and BP after the drug were similar in lean and obese rats. The serotonin agonist had no effect on UA mechanics in a group of paralyzed (pancuronium bromide) rats, despite similar elevations in BP. There was a smaller decrease (p < 0.05) in UA collapsibility that was also associated with increased upstream resistance when the drug was administered after bilateral hypoglossal nerve transection. We conclude that systemic administration of a serotonin(2A/2C) receptor agonist improves UA collapsibility predominantly, but not exclusively, via stimulation of the hypoglossal nerves and also increases upstream resistance, at least in part, through activation of nonhypoglossal motoneuronal pools innervating the UA muscles.

Physiologic evidence for the efficacy of positive expiratory pressure as an airway clearance technique in patients with cystic fibrosis

BACKGROUND AND PURPOSE

Individuals with cystic fibrosis (CF) have large amounts of infected mucus in their lungs, which causes irreversible lung tissue damage. Although patient-administered positive expiratory pressure (PEP) breathing has been promoted as an effective therapeutic modality for removing mucus and improving ventilation distribution in these patients, the effects of PEP on ventilation distribution and gas mixing have not been documented. Therefore, this preliminary investigation described responses in distribution of ventilation and gas mixing to PEP breathing for patients with moderate to severe CF lung disease.

SUBJECTS AND METHODS

The effects of PEP breathing on ventilation distribution, gas mixing, lung volumes, expiratory airflow, percentage of arterial blood oxyhemoglobin saturation (SpO(2)), and sputum volume were studied in 5 patients with CF (mean age=18 years, SD=4, range=13-22) after no-PEP, low-PEP (10-20 cm H(2)O), and high-PEP (>20 cm H(2)O) breathing conditions. Single-breath inert gas studies and lung function tests were performed before, immediately after, and 45 minutes after intervention. Single-breath tests assess ventilation distribution homogeneity and gas mixing by observing the extent to which an inspired test gas mixes with gas already residing in the lung.

RESULTS

Improvements in gas mixing were observed in all PEP conditions. By 45 minutes after intervention, the no-PEP group improved by 5%, the low-PEP group improved by 15%, and the high-PEP group improved by 23%. Slow vital capacity increased by 1% for no PEP, by 9% for low PEP, and by 13% for high PEP 45 minutes after intervention. Residual volume decreased by 13% after no PEP, by 20% after low PEP, and by 30% after high PEP. Immediate improvements in forced expiratory flow during the middle half of the forced vital capacity maneuver (FEF(25%-75%)) were sustained following high PEP but not following low PEP.

DISCUSSION AND CONCLUSION

This study demonstrated the physiologic basis for the efficacy of PEP therapy. The results confirm that low PEP and high PEP improve gas mixing in individuals with CF, and these improvements were associated with increased lung function, sputum expectoration, and SpO(2). The authors propose that improvements in gas mixing may lead to increases in oxygenation and thus functional exercise capacity.

Strain-specific Immune Response toHaemophilus influenzaein Chronic Obstructive Pulmonary Disease

Previous studies of immune response to Haemophilus influenzae after exacerbations of chronic obstructive pulmonary disease (COPD) have yielded contradictory results. Using homologous (infecting) strains and immunoassays to surface-exposed epitopes, we tested the hypothesis that adults with COPD make new antibodies to strain-specific, surface-exposed epitopes on H. influenzae after exacerbations. We collected clinical information, sputum, and serum monthly and during exacerbations from 81 patients with COPD over 56 months. Serum antibodies to H. influenzae after exacerbations associated with H. influenzae in sputum were detected with whole bacterial cell ELISA and bactericidal assays. An immune response to homologous H. influenzae occurred after 22 of 36 (61.1%) exacerbations with newly acquired strains compared with 7 of 33 (21.2%) exacerbations with preexisting strains (odds ratio [OR] = 4.4; 95%, 1.8 to 10.8; p = 0.001). An absence of an immune response was strongly associated with complement sensitivity (OR = 0.03; 95% confidence interval, 0.003 to 0.22; p = 0.001). New bactericidal antibodies developed after exacerbations were highly strain specific, showing bactericidal activity for only 11 of 90 (12.2%) heterologous strains. Development of an immune response to H. influenzae supports its role in causing exacerbations. The strain specificity of the immune response likely represents a mechanism of recurrent exacerbations.

Prediction of the apnea-hypopnea index from overnight pulse oximetry

STUDY OBJECTIVE

s: To compare the relative usefulness of the different indexes derived from pulse oximetry in the diagnosis of obstructive sleep apnea (OSA), and to determine if a combination of these indexes improves the prediction of the apnea-hypopnea index (AHI) measured by polysomnography.

DESIGN

Prediction model developed from 224 patients, validated prospectively in 101 patients from the same center (group 1) and in 191 patients from a different sleep center (group 2).

SETTING

Two independent sleep clinics run by university sleep specialists.

PARTICIPANTS

Patients who underwent polysomnography for suspicion of OSA.

INTERVENTIONS

The following indexes were calculated from pulse oximetry recordings performed simultaneously during polysomnography: (1) Delta index, the average of the absolute differences of oxygen saturation between successive 12-s intervals; (2) desaturation events per hour to 2%, 3%, and 4% levels; and (3) cumulative time spent below 90%, 88%, 86%, 84%, 82%, and 80% saturation.

MEASUREMENTS AND RESULTS

The best predictor was the Delta index, although desaturation events provided similar levels of diagnostic accuracy. An aggregation of multivariate models using combination of indexes reduced the prediction error (r(2) = 0.70) significantly (p < 0.05) compared to using the Delta index alone (r(2) = 0.60). The proportion of subjects from the validation groups within 95% confidence interval (CI) of the derivation group was 90% (95% CI, 83 to 95%) and 91% (95% CI, 86 to 95%) for groups 1 and 2, respectively. The overall likelihood ratios for the aggregated model in all patient groups were 4.2 (95% CI, 3.3 to 15.3), 3.4 (95% CI, 2.7 to 4.3), 3.0 (95% CI, 2.2 to 4.1), and 6.7 (95% CI, 4.9 to 9.2) for normal (AHI < 5/h), mild (AHI 5 to < 15/h), moderate (AHI 15 to < 30/h), and severe (AHI > or = 30/h) disease, respectively.

CONCLUSIONS

The Delta index and oxygen desaturation indexes provided similar levels of diagnostic accuracy. The combination of indexes improved the precision of the predicted AHI and may offer a potentially simpler alternative to polysomnography.

A novel approach for quality control of total lung capacity in the clinical pulmonary function laboratory: a study in a veteran population

OBJECTIVE

Quality control in the clinical pulmonary function laboratory has been well developed for spirometry and diffusing capacity but not for the measurement of TLC. The purpose of the present study was to test two approaches to this problem. First, we compared TLC by body plethysmography (TLCb) with a value predicted from TLC measured by multibreath helium dilution (TLCm). Concordance between the measured and predicted values would imply the validity of the measurements. Second, we measured the test-retest variability of TLCb, TLCm and TLC measured by single breath helium dilution (TLCs) to assess the consistency of the measurements.

METHODOLOGY

We performed a prospective study of 815 veterans.

RESULTS

The prediction of TLCb from TLCm improved (r2 increased from 0.44 to 0.64) when FEV1/FVC and the difference between TLCm and TLCs were added to the model. The coefficient of variation for test-retest of TLCs, TLCm and TLCb were 8.9, 7.1 and 5.4%, respectively. Of all tests, 5.9% were inconsistent based on pathophysiology or measurement error and attributed mostly to TLCm.

CONCLUSIONS

Prediction of TLCb from TLCm was not sufficiently accurate as to be useful for quality control. Comparison of TLCs, TLCm and TLCb may be useful for determining the internal data validity.

Relation between lung function and RBC distribution width in a population-based study

STUDY OBJECTIVES

Pulmonary function is dependent not only on smoking, but also on nutritional status. Since an increased RBC distribution width (RDW) has been associated with nutritional deficiencies, we postulated that RDW has an inverse relation to pulmonary function. The purpose of this study was to test this hypothesis.

DESIGN AND SETTING

A cross-sectional study was conducted of a random sample of the general population in western New York.

PARTICIPANTS

A total of 1,616 subjects of both genders who were aged 35 to 79 years and were free of respiratory disease.

INTERVENTIONS

None.

MEASUREMENTS

Pulmonary function was assessed from FEV(1), FVC, height, body weight, total pack-years of smoking, smoking status, hemoglobin concentration, and hematologic indexes, eosinophil count, education, and blood levels of retinol, beta-cryptoxanthin, and vitamin E.

RESULTS

We found a direct relation between RDW and the number of pack-years of smoking and smoking status, and an inverse relation between FEV(1) and FVC with RDW, even when potentially confounding variables such as smoking were taken into account. When the variability of FEV(1) due to smoking was used for comparison, an additional 27% of that variability in FEV(1) was explained by variations in antioxidant vitamin levels, and another 24% by RDW.

CONCLUSIONS

The results confirmed our hypothesis that there is an inverse relation between RDW and pulmonary function, and raise the possibility that RDW may be a biomarker for as-yet unidentified nutrients that affect pulmonary function.

The utility of neural network in the diagnosis of Cheyne-Stokes respiration

The aim of this study was to design a diagnostic model to identify patients with Cheyne-Stokes respiration (CSR-CSA) based on indices of oximetric spectral analysis. A retrospective analysis of oximetric recordings of 213 sleep studies conducted over a one-year period at a Veterans Affairs medical facility was performed. A probabilistic neural network (PNN) was developed from salient features of the oximetric spectral analysis, desaturation events and the delta index. A fivefold cross-validation was used to assess the accuracy of the neural network in identifying CSR-CSA. When compared to overnight polysomnography, the PNN achieved a sensitivity of 100% (95% confidence interval [CI] 85%-100%) and a specificity of 99% (95% 97%-100%) with a corresponding area under the curve of 99% (95% CI 99%-100%). When combined with overnight pulse oximetry, PNN offers an accurate and easily applicable tool to detect CSR-CSA.

Evidence for a positive association between pulmonary function and wine intake in a population-based study

BACKGROUND

Lung function is a strong predictor of cardiovascular and all-cause mortality. Previous studies suggest that alcohol exposure may be linked to impaired pulmonary function through oxidant-antioxidant mechanisms. Alcoholic beverages may be an important source of oxidants and antioxidants. We analyzed the relation of beverage-specific alcohol intake with forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) in a random sample of 1555 residents of Western New York, USA.

METHODS

We expressed pulmonary function as percent of predicted normal FEV1 (FEV1%) and FVC (FVC%) after adjustment for height, age, gender, and race. To obtain information on alcohol intake we used a questionnaire that reliably queries total alcohol and beverage-specific recent (past 30 days) and lifetime alcohol consumption.

RESULTS

Using multiple linear regression analysis after adjustment for covariates (pack-years of smoking, weight, smoking status, education, nutritional factors, and for FEV1%, in addition, eosinophil count), we observed no significant correlation between total alcohol intake and lung function. However, we found positive associations of recent and lifetime wine intake with FEV1% and FVC%. When we analyzed white and red wine intake separately, the association of lung function with red wine was weaker than with white wine.

CONCLUSION

While total alcohol intake was not related to lung function, wine intake showed a positive association with lung function. Although we cannot exclude residual confounding by healthier lifestyle in wine drinkers, differential effects of alcoholic beverages on lung health may exist.

Comparison of mortality between private for-profit and private not-for-profit hemodialysis centers: a systematic review and meta-analysis

CONTEXT

Private for-profit and private not-for-profit dialysis facilities provide the majority of hemodialysis care in the United States. There has been extensive debate about whether the profit status of these facilities influences patient mortality.

OBJECTIVE

To determine whether a difference in adjusted mortality rates exists between hemodialysis patients receiving care in private for-profit vs private not-for-profit dialysis centers.

DATA SOURCES

We searched 11 bibliographic databases, reviewed our own files, and contacted experts in June 2001-January 2002. In June 2002, we also searched PubMed using the "related articles" feature, SciSearch, and the reference lists of all studies that fulfilled our eligibility criteria.

STUDY SELECTION

We included published and unpublished observational studies that directly compared the mortality rates of hemodialysis patients in private for-profit and private not-for-profit dialysis centers and provided adjusted mortality rates. We masked the study results prior to determining study eligibility, and teams of 2 reviewers independently evaluated the eligibility of all studies. Eight observational studies that included more than 500 000 patient-years of data fulfilled our eligibility criteria.

DATA EXTRACTION

Teams of 2 reviewers independently abstracted data on study characteristics, sampling method, data sources, and factors controlled for in the analyses. Reviewers resolved disagreements by consensus.

DATA SYNTHESIS

The studies reported data from January 1, 1973, through December 31, 1997, and included a median of 1342 facilities per study. Six of the 8 studies showed a statistically significant increase in adjusted mortality in for-profit facilities, 1 showed a nonsignificant trend toward increased mortality in for-profit facilities, and 1 showed a nonsignificant trend toward decreased mortality in for-profit facilities. The pooled estimate, using a random-effects model, demonstrated that private for-profit dialysis centers were associated with an increased risk of death (relative risk, 1.08; 95% confidence interval, 1.04-1.13; P<.001). This relative risk suggests that there are annually 2500 (with a plausible range of 1200-4000) excessive premature deaths in US for-profit dialysis centers.

CONCLUSIONS

Hemodialysis care in private not-for-profit centers is associated with a lower risk of mortality compared with care in private for-profit centers.

Fasting glucose is a risk factor for breast cancer: a prospective study

There is some evidence that glucose and other factors related to glucose metabolism, such as insulin and insulin-like growth-factors (IGFs) may contribute to breast cancer development. The present study analyzed the hypothesis that serum glucose, insulin levels, and IGF-I pattern are associated with breast cancer using a nested case-control study. Between 1987 and 1992, 10,786 women ages 35-69 were recruited in a prospective study in Italy. Women with history of cancer and on hormone therapy were excluded at baseline. At recruitment, blood samples were collected after a 12-h fast between 7:30 and 9:00 a.m. from all of the study participants. After 5.5 years, 144 breast cancer cases were identified among the participants of the cohort. Four matched controls were chosen for each breast cancer case from members of the cohort who did not develop breast cancer during the follow-up period. In premenopausal women, glucose was associated with breast cancer risk: the age, body mass index, and reproductive variable adjusted relative risk (RR) for the highest quartile of serum glucose versus the lowest was 2.8 [95% confidence interval (CI), 1.2-6.5], and P for trend was 0.02. Insulin showed a weaker association with breast cancer, the adjusted RR of the highest quartile versus the lowest was 1.7 (95% CI, 0.7-4.1), and P for trend was 0.14, whereas the adjusted RR of the highest quartile of IGF-I was 3.1 (95% CI, 1.1-8.6), and P for trend was 0.01. Increased levels of insulin-like growth factor binding protein-3 (IGFBP)-3 were related to breast cancer risk: the adjusted RR for the highest quartile was 2.1 (95% CI, 0.95-4.75), and P for trend was 0.02. In postmenopausal women, the associations of glucose, insulin, and IGF-1 pattern were associated with breast cancer risk in heavier subjects characterized by a body mass index higher than 26. These results indicate that chronic alteration of glucose metabolism is related to breast cancer development.

New strains of bacteria and exacerbations of chronic obstructive pulmonary disease

BACKGROUND

The role of bacterial pathogens in acute exacerbations of chronic obstructive pulmonary disease is controversial. In older studies, the rates of isolation of bacterial pathogens from sputum were the same during acute exacerbations and during stable disease. However, these studies did not differentiate among strains within a bacterial species and therefore could not detect changes in strains over time. We hypothesized that the acquisition of a new strain of a pathogenic bacterial species is associated with exacerbation of chronic obstructive pulmonary disease.

METHODS

We conducted a prospective study in which clinical information and sputum samples for culture were collected monthly and during exacerbations from 81 outpatients with chronic obstructive pulmonary disease. Molecular typing of sputum isolates of nonencapsulated Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae, and Pseudomonas aeruginosa was performed.

RESULTS

Over a period of 56 months, the 81 patients made a total of 1975 clinic visits, 374 of which were made during exacerbations (mean, 2.1 per patient per year). On the basis of molecular typing, an exacerbation was diagnosed at 33.0 percent of the clinic visits that involved isolation of a new strain of a bacterial pathogen, as compared with 15.4 percent of visits at which no new strain was isolated (P<0.001; relative risk of an exacerbation, 2.15; 95 percent confidence interval, 1.83 to 2.53). Isolation of a new strain of H. influenzae, M. catarrhalis, or S. pneumoniae was associated with a significantly increased risk of an exacerbation.

CONCLUSIONS

The association between an exacerbation and the isolation of a new strain of a bacterial pathogen supports the causative role of bacteria in exacerbations of chronic obstructive pulmonary disease.

Controlled trial of a patient-completed history questionnaire: effects on quality of documentation and patient and physician satisfaction

The purpose of this work was to study the impact of a patient-self-completed history questionnaire upon the quality of the information in the medical record, resource utilization, patient satisfaction, and physician satisfaction. A controlled trial was performed in a primary care clinic of a public supported, urban, university hospital. The patients were mainly poor, minority, urban individuals visiting the clinic for their first primary care visit. The providers were attending physicians, nurse practitioners, and medical residents associated with the Department of Medicine teaching program. A self-administered history questionnaire was given to approximately half the new patients in a randomized, prospective manner. The physicians completed an assessment form on all new patients estimating the time spent, complexity of the case, and listing studies requested. If a history questionnaire was completed by the patient, the physician completed an assessment irrespective of whether it helped or hindered the evaluation of the patient. After the visit, nurses called the patient by telephone and asked questions concerning the patient's satisfaction. The patients' records were reviewed for the initial history papers. There were 127 patients receiving the history questionnaire and 114 controls. The presence of the history questionnaire in the medical record added to both the quantity and the quality of the information present. Of the provider responses, 87% (95% confidence interval: 78-93%) wanted all new patients to complete the questionnaire. Of the patients who received the questionnaire, all who were asked felt that all their issues were addressed, compared with only 83% in the control group (P = .015). No increases in physician time or in utilization of medical resources were found. The implementation of a self-administered history questionnaire in an urban primary care clinic resulted in improved chart quality and improved satisfaction of physicians and patients.

Association between plasma endothelin-1 levels and Cheyne-Stokes respiration in patients with congestive heart failure

STUDY OBJECTIVES

Elevated plasma endothelin-1 (ET-1) levels have been reported in association with hypoxia and congestive heart failure (CHF). Furthermore, Cheyne-Stokes respiration-central sleep apnea (CSR-CSA) has been found to correlate with the degree of pulmonary hypertension and the severity of CHF; however, the association between ET-1 levels and CSR-CSA has not been investigated previously.

SETTING

Veterans Affairs Medical Center.

INTERVENTIONS

We studied 46 consecutive patients with CHF (left ventricular function < or = 40%) who underwent right-heart catheterization and overnight polysomnography. Thirty-nine patients completed the study. Sixteen patients (41%) had CSR-CSA, 5 patients (13%) had obstructive apnea, and 18 patients (46%) had no sleep-disordered breathing. Circulating plasma ET-1 levels were assayed in patients with CSR-CSA and in patients with no sleep-disordered breathing using commercially available enzyme-linked immunosorbent assay kits.

RESULTS

ET-1 levels were significantly elevated in patients with CSR-CSA (mean +/- SD, 5.4 +/- 1.3 pg/mL) compared to those without central apnea (3.9 +/- 1.1 pg/mL; p < 0.01), and correlated with mean pulmonary artery pressure (r = 0.66, p < 0.01), pulmonary capillary wedge pressure (r = 0.56, p < 0.03), and central apnea frequency (r = 0.66, p < 0.01). In multivariate analysis, the severity of CSR-CSA was the only variable independently associated with plasma ET-1.

CONCLUSIONS

We conclude that elevated plasma ET-1 levels are linked to the severity of CSR-CSA. Whether ET-1 represents an important pathogenic factor in CSR-CSA or marker of its occurrence requires further evaluation.

A systematic review and meta-analysis of studies comparing mortality rates of private for-profit and private not-for-profit hospitals

BACKGROUND

Canadians are engaged in an intense debate about the relative merits of private for-profit versus private not-for-profit health care delivery. To inform this debate, we undertook a systematic review and meta-analysis of studies comparing the mortality rates of private for-profit hospitals and those of private not-for-profit hospitals.

METHODS

We identified studies through an electronic search of 11 bibliographical databases, our own files, consultation with experts, reference lists, PubMed and SciSearch. We masked the study results before determining study eligibility. Our eligibility criteria included observational studies or randomized controlled trials that compared private for-profit and private not-for-profit hospitals. We excluded studies that evaluated mortality rates in hospitals with a particular profit status that subsequently converted to the other profit status. For each study, we calculated a relative risk of mortality for private for-profit hospitals relative to private not-for-profit hospitals and pooled the studies of adult populations that included adjustment for potential confounders (e.g., teaching status, severity of illness) using a random effects model.

RESULTS

Fifteen observational studies, involving more than 26 000 hospitals and 38 million patients, fulfilled the eligibility criteria. In the studies of adult populations, with adjustment for potential confounders, private for-profit hospitals were associated with an increased risk of death (relative risk [RR] 1.020, 95% confidence interval [CI] 1.003-1.038; p = 0.02). The one perinatal study with adjustment for potential confounders also showed an increased risk of death in private for-profit hospitals (RR 1.095, 95% CI 1.050-1.141; p < 0.0001).

INTERPRETATION

Our meta-analysis suggests that private for-profit ownership of hospitals, in comparison with private not-for-profit ownership, results in a higher risk of death for patients.

Adhesion molecules in patients with coronary artery disease and moderate-to-severe obstructive sleep apnea

STUDY OBJECTIVES

It has been suggested that obstructive sleep apnea (OSA)-induced hypoxic stress might contribute to cardiovascular disorders by promoting expression of soluble adhesion molecules. The reported increase of circulating adhesion molecules in patients with OSA remains controversial because confounders such as cardiovascular risk factors and left ventricular function have not been adequately controlled for. We hypothesized that soluble intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, L-selectin, and E-selectin levels are correlated with OSA independent of coexisting coronary artery disease (CAD).

SETTINGS

University-affiliated teaching hospitals.

DESIGN AND PARTICIPANTS

A prospective study of 61 consecutive subjects with angiographically proven CAD deemed to have stable angina.

INTERVENTIONS

Fifteen patients (mean +/- SD) 61.2 +/- 1.9 years old with moderate-to-severe OSA (apnea-hypopnea index [AHI] > or = 20/h) were matched to a control group (AHI < or = 5/h) for age, gender, body mass index, and severity of CAD. Venous blood samples were collected the morning of the sleep study and assayed for human ICAM-1, VCAM-1, L-selectin, and E-selectin with commercially available enzyme-linked immunosorbent assay kits.

RESULTS

All but L-selectin were significantly increased in the OSA group compared to the control subjects (ICAM-1, 367.4 +/- 85.2 ng/mL vs 252.8 +/- 68.4 ng/mL, p = 0.008; VCAM-1, 961.5 +/- 281.7 ng/mL vs 639.1 +/- 294.4 ng/mL, p = 0.004; E-selectin, 81.0 +/- 30.4 ng/mL vs 58.1 +/- 23.2 ng/mL, p = 0.03, respectively). The increased levels of adhesion molecules correlated with the AHI and the oxygen desaturation index but not with the severity of hypoxemia or the frequency of arousals.

CONCLUSIONS

These findings suggest that OSA modulates the expression of proinflammatory mediators. Further studies should evaluate the influence of adhesion molecules on cardiovascular outcome in CAD patients with OSA.

Lung function in relation to intake of carotenoids and other antioxidant vitamins in a population-based study

Accumulating evidence suggests that dietary antioxidant vitamins are positively associated with lung function. No evidence exists regarding whether dietary carotenoids other than beta-carotene are related to pulmonary function. In 1995--1998 the authors studied the association of forced expiratory volume in 1 second and forced vital capacity as the percentage of the predicted value (FEV(1)% and FVC%, respectively) after adjustment for height, age, gender, and race with the intakes of several carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin, and lycopene) in a random sample of 1,616 men and women who were residents of western New York State, aged 35--79 years, and free from respiratory disease. They observed significant associations of lutein/zeaxanthin and vitamins C and E with FEV(1)% and FVC% using multiple linear regression after adjustment for total energy intake, smoking, and other covariates. When they analyzed all of these antioxidant vitamins simultaneously, they observed the strongest association of vitamin E with FEV(1)% and of lutein/zeaxanthin with FVC%. The differences in forced expiratory volume in 1 second and forced vital capacity associated with a decrease of 1 standard deviation of dietary vitamin E or lutein/zeaxanthin were equivalent to the influence of approximately 1--2 years of aging. Their findings support the hypothesis that carotenoids, vitamin C, and vitamin E may play a role in respiratory health and that carotenoids other than beta-carotene may be involved.