Heparin-protamine balance after neonatal cardiopulmonary bypass surgery

Essentials Heparin-protamine balance (HPB) modulates bleeding after neonatal cardiopulmonary bypass (CPB). HPB was examined in 44 neonates undergoing CPB. Post-operative bleeding occurred in 36% and heparin rebound in 73%. Thrombin-initiated fibrin clot kinetic assay and partial thromboplastin time best assessed HPB.

SUMMARY

Background Neonates undergoing cardiopulmonary bypass (CPB) are at risk of excessive bleeding. Blood is anticoagulated with heparin during CPB. Heparin activity is reversed with protamine at the end of CPB. Paradoxically, protamine also inhibits blood coagulation when it is dosed in excess of heparin. Objectives To evaluate heparin-protamine balance in neonates undergoing CPB by using research and clinical assays, and to determine its association with postoperative bleeding. Patients/Methods Neonates undergoing CPB in the first 30 days of life were studied. Blood samples were obtained during and after surgery. Heparin-protamine balance was assessed with calibrated automated thrombography, thrombin-initiated fibrin clot kinetic assay (TFCK), activated partial thromboplastin time (APTT), anti-FXa activity, and thromboelastometry. Excessive postoperative bleeding was determined by measurement of chest tube output or the development of cardiac tamponade. Results and Conclusions Of 44 neonates enrolled, 16 (36%) had excessive postoperative bleeding. The TFCK value was increased. By heparin in neonatal blood samples, but was only minimally altered by excess protamine. Therefore, it reliably measured heparin in samples containing a wide range of heparin and protamine concentrations. The APTT most closely correlated with TFCK results, whereas anti-FXa and thromboelastometry assays were less correlative. The TFCK and APTT assay also consistently detected postoperative heparin rebound, providing an important continued role for these long-established coagulation tests in the management of postoperative bleeding in neonates requiring cardiac surgical repair. None of the coagulation tests predicted the neonates who experienced postoperative bleeding, reflecting the multifactorial causes of bleeding in this population.

Maternal breast milk long-chain n-3 fatty acids are associated with increased risk of atopy in breastfed infants

BACKGROUND

Australia has one of the highest prevalence rates internationally of allergic conditions, such as asthma and eczema. Atopy is one hallmark for the development of allergic disease and predisposes to allergic inflammation in the target organs. omega-3 (n-3) fatty acids (FAs) are thought to act as precursors to the formation of less active inflammatory mediators, with the potential to reduce inflammation.

OBJECTIVE

To investigate whether increased n-3 FA levels in maternal breast milk are associated with a lower risk of developing atopy in infancy.

METHODS

Subjects were part of the prospective Melbourne atopy cohort study, which involved 620 children born into families where at least one first-degree relative had an atopic disease. Some 224 women (mean age 31.4+/-4.2 (SD) years, with 73.2% (n=164) having self-reported atopy) provided either a colostrum (n=194) or 3-month expressed breast milk (EBM) sample (n=118). Maternal colostrum and 3-month EBM samples were analysed for FA content by gas chromatography. Skin prick tests (SPTs) to six common allergens were performed on infants at 6, 12 and 24 months of age and on mothers who agreed at study entry.

RESULTS

For infants sensitized to foods at 6 months (n=29), the total n-3 FA level in the colostrum was significantly higher (P=0.004) as were levels of individual long-chain n-3 FAs, docosoapentaenoic acid (DPA, C22:5, P=0.001) and docosahexaenoic acid (DHA, C22:6, P=0.002) than in non-sensitized infants. Infants with aero-allergen sensitization at 24 months (n=30) had higher levels of the n-3 FA, DPA (P=0.002) and DHA (P=0.007), and similarly higher total n-3 FA (P=0.009) in maternal colostrum than those infants who were not sensitized.

CONCLUSION

Higher n-3 FA levels in the colostrum do not appear to confer protection against, but may be a risk factor for, the eventual development of atopy in high-risk breastfed infants.

Fatty acid levels and risk of asthma in young adults

BACKGROUND

There is current interest in the possible protective effect of long chain (n-3) fatty acids from fish in chronic lung diseases such as asthma. The aim of this community based cross sectional study was to determine whether plasma long chain (n-3) fatty acids, as a measure of dietary intake, differed between 1601 young adults with and without asthma.

METHODS

Subjects of mean (SD) age 34.6 (7.1) years completed a detailed respiratory questionnaire, food frequency questionnaire, skin prick testing, and lung function tests including methacholine challenge test for bronchial hyperreactivity (BHR) and had venous blood taken for analysis of plasma fatty acids. Plasma fatty acid levels (%) were analysed using multiple logistic regression with alternative definitions of asthma and atopy as the outcomes.

RESULTS

Atopy was not associated with any plasma fatty acid. The n-3 polyunsaturated fatty acids and n-6:n-3 ratio were not consistently associated with asthma or atopy. The n-6 polyunsaturated fatty acid dihomo gamma-linolenic acid (DHGLA) was positively associated with current asthma (OR=1.30, 95% CI 1.06 to 1.60), asthma (OR=1.34, 95% CI 1.13 to 1.60), and doctor diagnosed asthma (OR=1.25, 95% CI 1.06 to 1.48).

CONCLUSION

Plasma n-3 fatty acids are not associated with a reduced risk of asthma or atopy among young adults. The association of DHGLA with asthma warrants further research to determine a cause-effect relationship.

Residential characteristics predict changes in Der p 1, Fel d 1 and ergosterol but not fungi over time

BACKGROUND

Allergen and fungal exposures are important risk factors for asthma. We conducted a longitudinal analysis of allergen levels in Melbourne homes between 1996 and 1998 to examine the effects of changing residential characteristics on allergen and fungal levels. We also examined the changes in levels of indoor allergens.

METHODS

The subjects were participants in the European Community Respiratory Health Survey (ECRHS) in Melbourne. In 1996, 485 subjects participated in a follow-up study, which involved both home and laboratory visits. Dust and air samples were collected from participants' bedrooms and a validated residential questionnaire was administered. In 1998, 360 participants underwent further follow-up. House dust mite (Der p 1) and cat allergens (Fel d 1) and ergosterol were measured in dust.

RESULTS

We observed moderate within home correlations between 1996 and 1998 in floor Der p 1 (intraclass correlation ICC=0.48), bed Der p 1 (ICC=0.61), Fel d 1 (kappa=0.53) and ergosterol (ICC=0.28) levels. We found that the floor Der p 1 levels decreased from 1996 to 1998 in the homes of participants who moved to an attached home, moved their bedrooms to the first floor, removed fitted carpet or central heating. Replacing or vacuuming the mattress more than twice per year reduced levels of Der p 1 in the bed. Ergosterol levels were reduced by removing visible mould and fitted carpet.

CONCLUSIONS

These findings provide evidence to support current advice with regard to allergen avoidance in patients with dust mite and fungal allergies.

Wheeze not current asthma affects quality of life in young adults with asthma

BACKGROUND

A study was undertaken to investigate quality of life in asthma, defined by differing criteria, to see which may be most appropriate in epidemiological studies.

METHODS

The 426 adults were participants in the follow up phase of the European Community Respiratory Health Survey (ECRHS) in Melbourne. As part of the laboratory visit, participants completed the SF-36 quality of life questionnaire, a detailed respiratory questionnaire, and underwent lung function testing.

RESULTS

Both the physical component summary and the mental component summary scores were significantly worse in those with wheeze in the previous 12 months than in those without wheeze. Only the mental component summary score was significantly worse in those with current asthma than in those without. In contrast, in those with current asthma or bronchial hyperreactivity only, neither of the summary scales was significantly different between cases and controls.

CONCLUSIONS

Quality of life is severely impaired in individuals with wheeze in the previous 12 months while individuals with current asthma or bronchial hyperreactivity alone did not appear to have significantly reduced quality of life.

Reported adverse food reactions overestimate true food allergy in the community

OBJECTIVE

To determine the extent to which perceived adverse food reactions were associated with IgE mediated food allergy, as defined by skin prick testing (SPT).

DESIGN

A cohort epidemiological study. Participants underwent SPT to five common food allergens (cow's milk, peanut mix, egg white, shrimp and whole grain wheat mix) and were asked whether they had ever suffered any food 'illness/trouble', and if so to list such food(s). A positive SPT was defined as wheal diameter of > or =3 mm. Cohen's kappa (kappa) was used to assess the agreement between SPT and self-reported reactions to food(s) which contained the allergen of interest.

SETTING

Randomly selected adults who took part in the follow-up of the European Community Respiratory Health Survey (ECRHS) in 1998.

SUBJECTS

The subjects were 457 adults aged 26-50 y.

RESULTS

Fifty-eight (13%) adults were sensitised to at least one food allergen whilst 99 adults (22%) reported illness to food(s) nearly always. However, only seven subjects who reported illness to a food also had a positive SPT to the same food. The prevalence of adverse food reactions associated with IgE mediated allergy in the adult general population would be less than 1.5% (7/457). The agreement between SPT and self-reported illness to food(s) was poor for cow's milk (kappa=0) and wheat (kappa=0), slight for shrimp (kappa=0.16) and egg white (kappa=0.09) and fair for peanut mix (kappa=0.37).

CONCLUSIONS

There was little agreement between self-reported perceived illness to food(s) known to contain the food allergen of interest, and positive SPT, suggesting that most reactions are not due to IgE mediated food allergy.

Minimally invasive repair of pectus excavatum: a single institution's experience

BACKGROUND

The Nuss repair of pectus excavatum is a relatively new, minimally invasive surgical (MIS) alternative to the traditional open "Ravitch-type" operation. We have one of the larger single-center experiences to date, and we conducted this clinical study to evaluate our early experience, emphasizing initial outcome and technical modifications designed to minimize complications.

METHODS

A retrospective chart review was performed on 112 patients who underwent 116 pectus excavatum repairs between January 1995 and January 2001. The Nuss procedure was performed in 80 patients, and open repair was performed in 32 patients. Information about demographics, deformity, operative course, complications, and early outcome was recorded.

RESULTS

Operative duration was 143 minutes for the open group and 53 minutes for the Nuss MIS group (P <.001). Blood loss was 6 mL/kg for the open group and 0.5 mL/kg for the MIS group (P <.001). Postoperative hospitalization was 3.2 days for the open group versus 3.7 days for the MIS group (P<.05).

CONCLUSIONS

The MIS pectus repair can be performed safely with minimal blood loss and reduced operative time. Short-term analysis of the quality of repair, including absence of preoperative symptoms, patient satisfaction, and cosmetic appearance are encouraging.

Vascular anomalies and tracheoesophageal compression: a single institution's 25-year experience

BACKGROUND

Vascular rings are uncommon anomalies in which preferred strategies for diagnosis and treatment may vary among institutions. In this report, we offer a description of our approach and a review of our 25-year experience.

METHODS

A retrospective review was conducted of all pediatric patients with symptomatic tracheoesophageal compression secondary to anomalies of the aortic arch and great vessels diagnosed from 1974 to 2000.

RESULTS

Thirty-one patients (38%) of eighty-two patients (mean age, 1.7 years), were identified with double aortic arch, 22 patients (27%) with right arch left ligamentum, and 20 patients (24%) with innominate artery compression. Our diagnostic approach emphasized barium esophagram, along with echocardiography. This regimen was found to be reliable for all cases except those with innominate artery compression for which bronchoscopy was preferred, and except those with pulmonary artery sling for which computed tomography or magnetic resonance imaging, in addition to bronchoscopy, were preferred. Left thoracotomy was the most common operative approach (70 of 82; 85%). Ten patients (12%) had associated heart anomalies, and 6 (7%) patients underwent repair. Complications occurred in 9 (11%) patients and led to death in 3 (4%) patients.

CONCLUSIONS

In our practice, barium swallow and echocardiography are sufficient in diagnosing and planning the operative strategy in the majority of cases, with notable exceptions. Definitive intraoperative delineation of arch anatomy minimizes the risk of misdiagnosis or inadequate treatment.

The rising prevalence of asthma in young Melbourne adults is associated with improvement in treatment

BACKGROUND

Asthma is a common source of morbidity and is now recognized as a national health priority in Australia. Although a number of epidemiologic studies have been conducted in Australia to determine the prevalence of asthma in adults, it is unclear whether the prevalence is changing.

OBJECTIVES

To determine the prevalence in 1998 of self-reported asthma and respiratory symptoms among young adults and changes in prevalence between 1990 and 1999.

METHODS

Cross-sectional postal survey to 4,455 young adults (aged 20 to 44 years) randomly selected from the electoral rolls of the inner southeastern suburbs of metropolitan Melbourne. The survey instrument was the validated European Community Respiratory Health Survey screening questionnaire, which gathered data on self-reported respiratory symptoms, including whether asthma had been diagnosed. Identically worded questions from similar surveys conducted in 1990, 1992, and 1999 were used to compare changes in prevalence.

RESULTS

A response rate of 72% was achieved in 1998 after three mailings and telephone followup. Forty-two percent reported nasal allergies, 26% wheezed within the past 12 months, and 20% ever had asthma. The prevalence of doctor-diagnosed asthma was 18%, whereas 10% reported using asthma medications within the past 12 months. Nine percent of respondents reported an asthma attack within the past 12 months. The prevalence of having ever had asthma, doctor-diagnosed asthma, and using asthma medications had increased significantly since 1990. However, the prevalence of respiratory symptoms did not significantly change over this time.

CONCLUSIONS

The prevalence of asthma is likely to be rising, but the symptoms of asthma are being better managed in young Melbourne adults.

International prevalences of reported food allergies and intolerances. Comparisons arising from the European Community Respiratory Health Survey (ECRHS) 1991-1994

OBJECTIVE

The aim of this study was to report the prevalence, type and reported symptoms associated with food intolerance.

DESIGN

A cross-sectional epidemiological study involving 15 countries using standardized methodology. Participants answered a detailed interviewer-administered questionnaire and took part in blood, lung function and skin prick tests to common aeroallergens.

SETTING

Randomly selected adults who took part in the second phase of the European Community Respiratory Health Survey (ECRHS).

SUBJECTS

The subjects were 17280 adults aged 20-44 y.

RESULTS

Twelve percent of respondents reported food allergy/intolerance (range 4.6% in Spain to 19.1% in Australia). Atopic females who had wheezed in the past 12 months, ever had asthma or were currently taking oral asthma medications were significantly more likely to report food allergy/intolerance. Participants from Scandinavia or Germany were significantly more likely than those from Spain to report food allergy/intolerance. Respondents who reported breathlessness as a food-related symptom were more likely to have wheezed in the past 12 months, to have asthma, use oral asthma medications, be atopic, have bronchial hyperreactivity, be older and reside in Scandinavia.

CONCLUSION

Self-reported food allergy/intolerance differed significantly across multiple countries. The reasons for these differences were not explored in this study, but are likely to be largely due to cultural differences.

Asthma is more prevalent in rural New South Wales than metropolitan Victoria, Australia

OBJECTIVE

The aim of this study was to compare the prevalence of adult respiratory symptoms and conditions in a rural setting with a metropolitan setting.

METHODOLOGY

We used cross-sectional population surveys of respiratory health using the European Respiratory Health Survey screening questionnaire. A random sample of 4455 eligible young adults aged 20-44 years, from electoral rolls in south-eastern metropolitan Melbourne, Victoria, and 4521 from rural south-western New South Wales were surveyed.

RESULTS

Response rates of 72% (n=3194) and 69% (n=3121) were achieved in Melbourne and the Riverina, respectively. Respondents from the Riverina reported significantly higher prevalences of nocturnal dyspnoea (P<0.01), chronic bronchitis (P=0.03), an asthma attack in the previous 12 months (P<0.001), ever having had asthma (P<0.001) and doctor-diagnosed asthma (P<0.001) compared to those from Melbourne. However, among those with 'asthma attacks in the last 12 months', Melbourne respondents experienced a higher frequency of attacks (P<0.05). Riverina respondents reported a higher prevalence of smoking (P<0.05) and smoked more cigarettes on average (P<0.001) than Melbourne respondents. However, annoyance from air pollution was higher in Melbourne than in the Riverina.

CONCLUSIONS

These results suggest that asthma is more prevalent in rural southern New South Wales than in Melbourne but follows a different pattern of exacerbations.

Thoracotomy for persistent bronchopleural fistula in the very low birth weight infant

Although conservative treatment is appropriate for most very low birth weight infants with bronchopleural fistulas, early surgical closure may improve survival in properly selected patients. We report our experience with successful surgical closure in 3 consecutive neonates weighing <800 g.

Dietary marine fatty acids (fish oil) for asthma

BACKGROUND

Epidemiological studies suggest that a diet high in marine fatty acids (fish oil) may have beneficial effects on inflammatory conditions such as rheumatoid arthritis and possibly asthma.

OBJECTIVES

1. To determine the effect of marine n-3 fatty acid (fish oil) supplementation in asthma. 2. To determine the effect of a diet high in fish oil in asthma.

SEARCH STRATEGY

The Cochrane Airways Review Group register was search using the terms: marine fatty acids OR diet OR nutrition OR fish oil OR eicosapentaenoic acid OR EPA. Bibliographies of retrieved trials were searched and fish oil manufacturers contacted.

SELECTION CRITERIA

Randomised controlled trials in patients with asthma more than two years of age were included. The study duration had to be in excess of 4 weeks. Double blind trials were preferred, but single-blind and open trials were also reviewed for possible inclusion. Three reviewers read each paper, blind to its identity. Decisions concerning inclusion were made by simple majority. Quality assessment was performed by all three reviewers independently.

DATA COLLECTION AND ANALYSIS

The only comparison possible was between marine n-3 fatty acid supplementation and placebo. There were insufficient trials to examine dietary manipulation alone.

MAIN RESULTS

Eight randomised controlled trials conducted between 1986 and 1998 satisfied the inclusion criteria. Six were of parallel design and two were cross-over studies. Seven compared fish oil with placebo whilst one compared high dose vs low dose marine n-3 fatty acid supplementation. None of the included studies reported asthma exacerbations, health status or hospital admissions. There was no consistent effect on any of the analyzable outcomes: FEV1, peak flow rate, asthma symptoms, asthma medication use or bronchial hyper reactivity. The single study performed in children also combined dietary manipulation with fish oil supplementation and showed improved peak flow and reduced asthma medication use. There were no adverse events associated with fish oil supplements. Updated Search conducted August 2000. No new trials were found.

REVIEWER'S CONCLUSIONS

There is little evidence to recommend that people with asthma supplement or modify their dietary intake of marine n-3 fatty acids (fish oil) in order to improve their asthma control. Equally, there is no evidence that they are at risk if they do so.

Current guidelines for antibiotic prophylaxis of surgical wounds

Appropriately administered antibiotic prophylaxis reduces the incidence of surgical wound infection. Prophylaxis is uniformly recommended for all clean-contaminated, contaminated and dirty procedures. It is considered optional for most clean procedures, although it may be indicated for certain patients and clean procedures that fulfill specific risk criteria. Timing of antibiotic administration is critical to efficacy. The first dose should always be given before the procedure, preferably within 30 minutes before incision. Readministration at one to two half-lives of the antibiotic is recommended for the duration of the procedure. In general, postoperative administration is not recommended. Antibiotic selection is influenced by the organism most commonly causing wound infection in the specific procedure and by the relative costs of available agents. In certain gastrointestinal procedures, oral and intravenous administration of agents with activity against gram-negative and anaerobic bacteria is warranted, as well as mechanical preparation of the bowel. Cefazolin provides adequate coverage for most other types of procedures.

The effects of monosodium glutamate in adults with asthma who perceive themselves to be monosodium glutamate-intolerant

BACKGROUND

Many previous clinical studies of food-induced asthma suffer from inadequate baseline or control data. A statistically valid, randomized, double-blind, placebo-controlled, monosodium glutamate (MSG)-challenge protocol was developed for identifying early and late asthmatic reactions in an individual.

OBJECTIVE

We sought to determine whether MSG would induce bronchoconstriction in a group of adults with asthma who perceived that they were MSG sensitive.

METHODS

Twelve subjects (seven women, mean age 35.3 years) with clinically documented asthma and a perception of MSG-induced asthma were recruited. FEV1 and peak expiratory flow data were obtained for 3 whole control days, as well as time-matched data for 3 separate challenge days (1 gm MSG, 5 gm MSG, and 5 gm lactose [placebo]). Opaque capsule challenges were given as a single dose in the morning after an overnight fast. Subjects complied with an elimination diet throughout the study. Nonspecific bronchial hyperresponsiveness was measured at baseline, after the control days, and at the conclusion of the challenges. Venous blood samples were taken at baseline and on each challenge day to determine soluble inflammatory marker (eosinophil cationic protein and tryptase) activity.

RESULTS

No immediate or definite late asthmatic reactions occurred. One subject's FEV1 declined more than 15% on MSG challenge, but 95% confidence limits for the control-day spirometry showed that this decline was within her daily variation, hence the challenge was deemed to be negative. No significant changes in bronchial hyperresponsiveness or soluble inflammatory markers were found.

CONCLUSIONS

MSG-induced asthma was not demonstrated in this study. This study highlighted the importance of adequate baseline and control data and indicated that such a rigorous protocol for individual assessment is feasible.

Open pelvic fracture and fecal diversion

BACKGROUND

Mandatory fecal diversion has been advocated as an appropriate measure to prevent infection in the clinical setting of an open pelvic fracture. However, the efficacy of this practice has not been verified by prospective investigation and has received only inconsistent support from retrospective analyses.

OBJECTIVE

To determine whether fecal diversion is associated with a substantially lower incidence of abdominopelvic infectious complications in patients with open pelvic fractures.

DESIGN

Case-control study.

SETTING

University-based tertiary care, level I trauma center.

METHODS

The current study reviews our experience with 60 cases admitted from 1987 to 1993 to Harborview Medical Center, a regional level I trauma center. Data collected on each patient included age, sex, Injury Severity Score, Glasgow Coma Scale, initial heart rate and systolic blood pressure, location and severity of wound, fracture pattern, pelvic stability, time to open reduction internal fixation or external fixation, mortality, use of fecal diversion, and incidence and location of infection. Review of the literature produced an additional 186 patients amenable to analysis.

RESULTS

Fecal diversion was performed in 19 patients, 5 (26%) of whom experienced subsequent abdominopelvic infectious morbidity. Of the remaining 41 patients, 7 patients (17%) experienced infectious complications. The 2 groups (diversion vs no diversion) were comparable with regard to relevant demographic and clinical characteristics of injury severity. Combining the present series with those reported by others gave a composite series of 246 patients. For the composite series, diversion was performed in 70% of patients. Infection developed in 27% of patients who underwent diversion vs 29% in patients who did not. In the present series, only mechanical instability was determined by stepwise logistic regression to be significantly associated with pelvic infection. This association was not altered by diversion status.

CONCLUSIONS

Diversion of the fecal stream to protect open pelvic fractures is not associated with a lower incidence of abdominopelvic infectious complications. Diversion may offer protection to a select group of patients with extensive soft tissue injury or posterior wounds. Mechanical instability was independently associated with infection.

Do dairy products induce bronchoconstriction in adults with asthma?

BACKGROUND

Dairy products have often been implicated as a cause of exacerbation of asthma, but there is little scientific evidence to support this hypothesis.

OBJECTIVE

We sought to determine whether dairy products induce bronchoconstriction in a group of adults with asthma.

METHODS

Twenty subjects with asthma (13 women and 7 men) were recruited from respondents who had previously completed a food and asthma questionnaire. Ten subjects perceived that their asthma became worse with ingestion of dairy products (positive perceivers), whereas ten were negative perceivers. None of the subjects had positive skin prick test results with cow's milk. The study was a randomized, cross-over, double-blind, placebo-controlled trial. Subjects complied with a dairy-free diet throughout the study. The active challenge was a single-dose drink equivalent to 300 ml of cow's milk. A positive reaction was defined as a 15% reduction in both FEV1 and peak expiratory flow (PEF) on the active challenge day compared with results obtained at the same time on the placebo day.

RESULTS

For both FEV1 and PEF there were no statistically significantly differences in group means between active challenge and placebo challenge, between sequence of administration, or between perceptions. Nine subjects showed FEV1 or PEF changes that were greater than 15% of baseline values: four patients showed changes after both active and placebo treatment; two after treatment with placebo only; and three after active treatment alone. Of the latter group, two subjects showed changes only in PEF, and when one of these subjects underwent a further detailed study, no asthmatic reaction could be demonstrated.

CONCLUSION

It is unlikely that dairy products have a specific bronchoconstrictor effect in most patients with asthma, regardless of their perception.

Reported food intolerance and respiratory symptoms in young adults

The aim of the study was to assess the ability of the European Community Respiratory Health Survey (ECRHS) questionnaire to provide data on the prevalence, type and reported symptoms associated with food intolerance from a group of young adults in Melbourne. Six hundred and sixty nine randomly selected subjects completed the questionnaire with 553 attending the laboratory for skin-prick tests, anthropometry, and ventilatory function tests. A further 207 symptomatic participants completed the questionnaire, with 204 of them attending the laboratory. Seventeen per cent of all respondents reported food intolerance or food allergy. A wide variety of food items was cited as being responsible for food-related illnesses. Those with current asthma did not report food-related illness more frequently than those without asthma. Respondents who reported respiratory symptoms following food ingestion were more likely to be atopic, to have used inhaled respiratory medications in the previous 12 months, reported less exposure to regular passive smoking over the past 12 months and weighed more. These associations between respiratory symptoms and food intolerance require further prospective investigation and verification. The importance of using appropriate dietary methodology in future studies for determining diet-disease relationships was highlighted by this study.

Patients' perceptions of food-induced asthma

BACKGROUND

The influence of diet in asthma control remains unclear. However, there is likely to be a wide gap between patient perceptions and the probable actual role. Some 20-60% of people with asthma report food as a trigger factor while approximately 2.5% react to double-blind placebo-controlled challenges. The aim of this study was to determine: the frequency, type and sources of dietary advice being offered to patients, the prevalence of dietary modification, whether dietary changes were perceived to be of benefit and the type and sources of food/beverage reactions that people perceive they have experienced.

METHOD

A self-administered 'food and asthma' questionnaire was developed and mailed to 156 consecutive Alfred Hospital Asthma and Allergy Clinic patients registered on a computer database.

RESULTS

The completed questionnaire response rate was 86.5%. Dietary advice had been offered to 47% of respondents while 61% had tried to modify their diet. Dietary restriction was the most common dietary modification. Where dietary restriction had occurred 79% of respondents perceived that this had improved their asthma control. A doctor was the most common source of dietary advice. Seventy-three per cent reported that food induced asthma.

CONCLUSION

We confirmed that patients with asthma perceived diet to be important in their asthma control and that dietary modification is common despite its lack of objective basis. The influence of diet and asthma requires more research, evaluation and clinical attention.

Four-dimensional spectral-spatial imaging using projection reconstruction

An n-dimensional (n-D) filtered backprojection image reconstruction algorithm has been developed and used in the reconstruction of 4-D spectral-spatial magnetic resonance imaging (MRI) data. The algorithm uses n-1 successive stages of 2-D filtered backprojection to reconstruct an n-D image. This approach results in a reduction in computational time on the order of N(n-2) relative to the single-stage technique, where N(n) is the number of elements in an n-D image. The authors describe implementation of the algorithm, including digital filtering and sampling requirements. Images obtained from simulated data are presented to illustrate the accuracy and potential utility of the technique.

Electron spin resonance microscopy of an in vitro tumour model

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