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Biomedical subjects

S K Field

Publications and source records attributed to S K Field.

At least 19 recordsLinked to original sources
PubMed2005

Tuberculosis in Calgary, Canada, 1995-2002: site of disease and drug susceptibility.

SETTING: A centre managing all tuberculosis (TB) cases in the population of the Calgary region in Canada. OBJECTIVE: To facilitate the diagnosis and management of TB by examining the distribution of TB by site of disease and the prevalence and pattern of drug-resistant Mycobacterium tuberculosis in a north American setting. DESIGN: A retrospective analysis of data collected at the time of diagnosis of all TB cases recorded during the 8-year period 1995-2002. Data collected included demographic information, site of disease, method of diagnosis and M. tuberculosis drug susceptibility. RESULTS: During the 8-year period, 435 cases of TB were diagnosed: 49% had exclusively extra-pulmonary disease. Lymph node disease (usually cervical) accounted for 44% of the extra-pulmonary cases. A culture of M. tuberculosis resistant to at least one first-line anti-tuberculosis drug was detected in 16% of the initial isolates. All of the resistant strains were found in foreign-born patients and resistance was more common in patients from Asia (19%) and in previously treated patients (26%). CONCLUSION: Extra-pulmonary TB is common in the foreign-born population in the Calgary region, and this pattern may be more widespread than is realised. Drug-resistant strains of TB were more common in foreign-born and previously treated patients.

Alberta↗
PubMed2001

Underlying mechanisms of respiratory symptoms with esophageal acid when there is no evidence of airway response.

Although a strong association exists between gastroesophageal reflux (GER) and asthma, results of studies designed to maximize the likelihood of identifying that GER worsens pulmonary function in patients with asthma have been negative or inconclusive. Asthma symptoms worsen during symptomatic reflux episodes, and asthma symptom severity correlates with the severity of symptomatic reflux. Various reasons have been proposed to explain these findings. Discomfort associated with GER can cause reflux-associated respiratory symptoms even when pulmonary function is normal. New findings suggest that increases in minute ventilation rather than inhibition of diaphragm activity are responsible for the changes in respiratory sensation during acid perfusion of the esophagus in nonasthmatic subjects. These results may also pertain to asthmatic patients, because increasing minute ventilation can cause dyspnea and bronchospasm in this population. Treating GER, either medically or surgically, may improve asthma symptoms by preventing GER-induced changes in minute ventilation.

Airway Resistance↗
PubMed2001

Predicting emergency department utilization in adults with asthma: a cohort study.

A consecutive sample of 378 adults with asthma were assessed at a university asthma program and then interviewed 1 year later regarding their need for emergency department (E.D.) asthma treatment. The purpose of this prospective cohort study was to determine whether any of their initial features could predict their subsequent need for E.D. asthma treatment. At one year, a total of 73 of the subjects had attended emergency departments for asthma. On entry, the 73 subjects had demonstrated more self-reported lifestyle restriction from asthma and more hospital admissions E.D. visits for asthma as well as poorer asthma control or than had the 305 subjects who had not required E.D. asthma treatment since entry to the cohort. This study suggests that special attention should be paid to subjects with asthma that interferes with their lifestyle and to those who have needed hospital admission for asthma.

Adolescent↗
PubMed2001

Extraesophageal manifestations of gastroesophageal reflux.

BACKGROUND: Associations have been reported between gastroesophageal reflux and a variety of upper and lower respiratory tract conditions. Respiratory conditions and GER are common and would be expected to coexist in many patients. Whether there is a relationship between GER and these conditions and its nature remain controversial. The purpose of this paper is to review the relationship between GER and these conditions. METHODS: Searches of the 1966 to 2000 MEDLINE database were undertaken to identify appropriate studies. The terms gastroesophageal reflux, medical antireflux therapy, and antireflux surgery were combined with rhinitis, sinusitis, laryngitis, laryngeal stricture, croup, apnea, dental caries, aspiration pneumonia, idiopathic pulmonary fibrosis, cystic fibrosis, asthma, COPD, chronic bronchitis, bronchiectasis and cough. RESULTS: Papers were identified that related any of the above respiratory conditions to gastroesophageal reflux or to antireflux therapy. Most suggested a causative relationship between GER and these conditions but only a few of the studies were controlled. Controlled studies demonstrate a strong association between GER and asthma and cystic fibrosis. CONCLUSIONS: A strong association between GER and some respiratory conditions has been demonstrated in controlled trials. It is uncertain whether the association is due to GER causing respiratory disease or vice versa. It is clear that further properly powered, controlled, randomized trials of the relationship between GER and antireflux therapy and respiratory disease need to be conducted.

Journal Article↗
PubMed1999

A critical review of the studies of the effects of simulated or real gastroesophageal reflux on pulmonary function in asthmatic adults.

OBJECTIVE: To identify and critically review the published peer-reviewed, English-language studies of the effects of both spontaneous and simulated gastroesophageal reflux (GER) on pulmonary function in asthmatic adults. DESIGN: Using the 1966 to 1997 MEDLINE database, the terms asthma and lung disease were combined with GER to identify studies of the effects of GER and acid perfusion (AP) of the esophagus on pulmonary function. The bibliographies were also reviewed. Studies of asthmatics with and without symptomatic GER were analyzed both together and separately. RESULTS: A total of 254 citations, including 180 published in English, were identified. Among these were 18 studies of GER and AP in asthmatic adults. These reports, which contain data on 312 asthmatics, found that the FEV1 and the midexpiratory rate did not change during AP and GER in the studies containing 97% and 94% of the asthmatics, respectively. Flow volume loop indexes, including the flow at 50% of the vital capacity (V50), flow at 25% of the vital capacity, and the peak expiratory flow rate, did not change during AP or GER in the studies with 77%, 60%, and 65% of the asthmatics, respectively. Small changes in the resistance were reported in the studies containing 42% of the asthmatics. Among asthmatics without symptomatic GER, no changes in spirometry, resistance, and flow volume indexes were found, except for a 10% decline in V50 in one study with seven subjects. CONCLUSIONS: In asthmatics with GER, the effects of AP on pulmonary function are minimal, and only a minority are affected. The literature does not support the conclusion that asymptomatic reflux contributes to worsening lung function.

Adult↗
PubMed1999

The effects of antireflux surgery on asthmatics with gastroesophageal reflux.

BACKGROUND: Antireflux therapy, including surgery, has been advocated for asthma patients with gastroesophageal reflux (GER). A recent review of medical antireflux therapy reported improvements in asthma symptoms and medication requirements but no improvement in pulmonary function. The purpose of this article is to review the available literature on the effects of antireflux surgery in asthma. METHOD: Using the Medline 1966 to August 1998 database, lung disease, asthma, and pulmonary function were combined with GER and different antireflux surgeries, including fundoplication. Reference lists of identified articles were also reviewed. RESULTS: Combining the terms asthma and GER identified 271 articles, including 193 in English. Searching the term fundoplication identified 497 articles, including 413 in English. Twenty-four reports addressed the effects of antireflux surgery in asthma. Only two studies were controlled. Asthmatic data could not be distinguished from that of other subjects in five articles. The remainder were case series, retrospective reviews, or uncontrolled studies. Ten reports included data on < or = 10 patients. Two studies were only published as abstracts. A total of 417 asthma patients were included in the identified reports. Antireflux surgery improved GER symptoms, asthma symptoms, asthma medication use, and pulmonary function in 90%, 79%, 88%, and 27%, respectively. CONCLUSIONS: Antireflux surgery may improve GER and asthma symptoms and decrease medication requirements, but it has little effect on pulmonary function. The effects of antireflux surgery on asthma are similar to those of medical antireflux therapy.

Asthma↗
PubMed1999

Gastroesophageal reflux and asthma: are they related?

The relationship between asthma and gastroesophageal reflux (GER) is controversial. This paper reviews the evidence for an association between them, the effect of asthma on GER, and the effects of GER and antireflux therapy on asthma. The association between the two conditions seems firm but studies of the effects of GER on asthma and asthma on GER are contradictory. Critical review suggests that GER affects asthma symptoms but not pulmonary function. Antireflux therapy improves asthma symptoms and reduces medication requirements but does not improve pulmonary function. The paradox of GER causing asthma symptoms but not changing pulmonary function may be explained by its increasing minute ventilation rather than triggering bronchospasm.

Asthma↗
PubMed1998

The effects of acid perfusion of the esophagus on ventilation and respiratory sensation.

The relationship between gastroesophageal reflux (GER) and asthma remains controversial. Asthma symptoms worsen with GER, but are not consistently related to changes in lung function. The purpose of this study was to determine whether acid perfusion (AP) of the esophagus alters ventilation and causes respiratory symptoms. Nonasthmatic patients with normal lung function and esophageal disease (16 females and nine males, FEV1 %predicted = 99+/-9.6), underwent a Bernstein test after motility testing. Airflow, rib cage (Vrc), and abdominal (Vab) tidal volumes, esophageal (Pes) and gastric (Pga) pressure, and surface (Es) and esophageal (Edi) diaphragm electromyographic (EMG) signals were measured. Throat, swallowing, chest, and stomach discomfort and respiratory sensation were estimated with the Borg scale. Minute ventilation (VE) increased during AP and declined during recovery with saline perfusion of the esophagus (7.1+/-1.5 to 8.5+/-2.4 to 7.3+/-2.1 L/min; n = 25; p = 0.0002). Respiratory rate (RR) went from 13.6+/-2.6 to 15.8+/-3.4 to 15.3+/-3.1 breaths/min (n = 25; p = 0.0002) during AP. VE was greater in the Bernstein-positive patients during AP. Tidal volume (VT), Vrc, Vab, Pes, Pga, Es, and Edi did not change during AP. Chest discomfort (D) correlated with ventilation (VE = 0.7 + 0.8 D; r = 0.67; p < 0.001) and respiratory effort sensation (B) (B = 0.2 + 0.4 VE; r = 0.70; p < 0.001) during AP. AP did not inhibit diaphragm activity. Increased VE may explain the paradox of GER worsening respiratory symptoms without changing lung function.

Asthma↗
PubMed1998

Does medical antireflux therapy improve asthma in asthmatics with gastroesophageal reflux?: a critical review of the literature.

OBJECTIVE: Identify and critically review the peer-reviewed, English-language studies of the effects of medical antireflux therapy in asthmatics with gastroesophageal reflux (GER). DESIGN: Using the 1966 to 1996 MEDLINE database, asthma was combined with GER to identify all studies of the effects of medical antireflux therapy on asthma control. The articles' bibliographies were also reviewed. Studies were graded according to Sackett's criteria and grouped by levels of evidence. RESULTS: A total of 242 citations were found; 171 were published in English. Twelve studies of the effects of medical antireflux therapy on asthma control, with a total of 326 treated patients, were identified. Eight studies were placebo-controlled, three were open studies, and one used an untreated control. Eight studies treated 20 or fewer patients. Reflux symptoms either did not improve or the effects of antireflux therapy on them were not reported in four studies. The combined data from the controlled medical antireflux studies showed that: (1) asthma symptoms improved in 69% of the subjects; (2) asthma medication use was reduced in 62% of the subjects; (3) evening peak expiratory flow (PEF), but not PEF at other times, improved in 26% of the subjects; and (4) spirometry did not improve in any of the placebo-controlled antireflux studies. CONCLUSIONS: Analysis of the combined data suggests that medical antireflux therapy improves asthma symptoms, may reduce asthma medication use, but has minimal or no effect on lung function.

Antacids↗
PubMed1997

The effect of a peak flow-based action plan in the prevention of exacerbations of asthma.

STUDY OBJECTIVE: To determine the effect of a symptom-based and a peak flow-based action plan in preventing acute exacerbations in subjects with poorly controlled asthma. DESIGN: A randomized controlled trial in which subjects who had required urgent treatment for their asthma were allocated to receive no action plan, a symptom-based plan, or a peak flow-based action plan. SETTING: A university hospital asthma clinic. POPULATION: One hundred fifty subjects were recruited after attending an emergency department or a clinic for urgent treatment of asthma. INTERVENTIONS: All subjects received evaluation and education for asthma before being randomly allocated to receive no action plan, a symptom-based action plan, or a peak flowmeter and a peak flow-based action plan. MEASUREMENTS: Subjects were assessed by questionnaire at 3 and 6 months after enrollment with questions relating to their asthma control and their need for urgent treatment or hospital admission for asthma. RESULTS: At 6 months after enrollment, although all three intervention groups experienced improvement in their asthma control, there was a striking reduction in emergency department visits for asthma only in the peak flow-based action plan group (p=0.006). No significant difference in emergency visits was apparent between the symptom-based action plan and no action plan groups. CONCLUSIONS: We conclude that a peak flow-based action plan is effective, at least in the short term, in protecting patients with asthma against severe exacerbations of their disease.

Adolescent↗
PubMed1996

Prevalence of gastroesophageal reflux symptoms in asthma.

STUDY OBJECTIVE: To determine the prevalences of symptomatic gastroesophageal reflux (GER), reflux-associated respiratory symptoms (RARS), and reflux-associated beta-agonist inhaler use in asthmatics. DESIGN: Questionnaire-based, cross-sectional analytic survey. SETTING: Outpatient asthma and clinical research clinics attached to the University of Calgary tertiary care centre and two family practices. PATIENTS: Asthma group consisted of 109 patients referred to an outpatient asthma clinic. First control group consisted of 68 patients visiting their family physicians. Second control group consisted of 67 patients with thyroid disease, hypercholesterolemia, or diabetes participating in drug trials. RESULTS: Among the asthmatics, 77%, 55%, and 24% experienced heartburn, regurgitation, and swallowing difficulties, respectively. Symptoms were less prevalent in the control groups. At least one antireflux medication was required by 37% of asthmatics (p < 0.001, vs controls). None of the asthma medications were associated with an increased likelihood of symptomatic GER. In the week prior to completing the questionnaire, 41% of the asthmatics noted RARS, including cough, dyspnea, and wheeze and 28% used their inhalers while experiencing GER symptoms. Inhaler use correlated with the severity of heartburn (r = 0.28, p < 0.05) and regurgitation (r = 0.40, p < 0.05) CONCLUSIONS: The questionnaire demonstrated a greater prevalence of GER symptoms, RARS, and reflux-associated inhaler use in asthmatics. This excessive inhaler use may explain how GER indirectly causes asthma to worsen.

Adult↗