Mismatch 'never events' in hip and knee arthroplasty: a cohort and intervention study

AIMS

The aim of this study was to give estimates of the incidence of component incompatibility in hip and knee arthroplasty and to test the effect of an online, real-time compatibility check.

MATERIALS AND METHODS

Intraoperative barcode registration of arthroplasty implants was introduced in Denmark in 2013. We developed a compatibility database and, from May 2017, real-time compatibility checking was implemented and became part of the registration. We defined four classes of component incompatibility: A-I, A-II, B-I, and B-II, depending on an assessment of the level of risk to the patient (A/B), and on whether incompatibility was knowingly accepted (I/II).

RESULTS

A total of 26 524 arthroplasties were analyzed. From 12 307 procedures that were undertaken before implementation of the compatibility check, 21 class A incompatibilities were identified (real- or high-risk combinations; 0.17%; 95% confidence interval (CI) 0.11 to 0.26). From 5692 hip and 6615 knee procedures prior to implementation of the compatibility check, we found rates of class A-I incompatibility (real- or high-risk combinations unknowingly inserted) of 0.14% (95% CI 0.06 to 0.28) and 0.17% (95% CI 0.08 to 0.30), respectively. From 14 217 procedures after the introduction of compatibility checking (7187 hips and 7030 knees), eight class A incompatibilities (0.06%; 95% CI 0.02 to 0.11) were identified. This difference was statistically significant (p = 0.008).

CONCLUSION

Our data presents validated estimates of the baseline incidence of incompatibility events for hip and knee arthroplasty procedures and shows that a significant reduction in class A incompatibility events is possible using a web-based recording system. Cite this article: Bone Joint J 2019;101-B:960-969.

Quality assurance ofallergen-specific immunotherapy during a national outbreak of anaphylaxis: results of a continuous sentinel event surveillance system

BACKGROUND AND OBJECTIVE

Subcutaneous allergen-specific immunotherapy (SCIT) is an effective treatment for patients with allergic asthma and rhinitis. SCIT may be performed in many different ways and good safety profiles have been published. Other studies, however, have reported high frequencies of severe adverse events (SAEs) but without identifying the causes. After an increase in SCIT-related SAEs in Denmark between 2003 and 2004, strict performance regulations were imposed by the authorities. Because safety data from national databases were not available, we implemented a surveillance system aimed at identifying the causes of SAEs.

METHODS

We prospectively registered the number of injections and SAEs during SCIT. A slow up-dosing regimen was used and adherence to international standards was optimized.

RESULTS

No SAEs were observed with 28 992 injections. The maximal risk per injection was calculated at < 1.3 per 10 000 injections.

DISCUSSION

Our results confirm the good safety profile of SCIT. We applied a sentinel SCIT surveillance system that may offer a means of guaranteeing safety by providing online feedback to all participating clinics when SAEs occur in order to explore their causes by root course analyses performed by all participants. Furthermore, such quality assurance documentation may facilitate wider acceptance of SCIT by health care administrators, clinicians, and patients.

Interactions between Carrageenans and Milk Proteins: A Microstructural and Rheological Study

Gels were produced using kappa-, iota-, or hybrid-carrageenan at a low (0.2-0.25%) and a high (0.7-1.0%) dosage in skim milk. The microstructure of carrageenan and protein was observed by confocal laser scanning microscopy using direct immunostaining. Additionally, rheology was used to characterize the gels. The low kappa- and iota-carrageenan dosages resulted in gels with a fine stranded carrageenan-protein microstructure and emulsion-like inclusions, while the high dosages resulted in strongly flocculated microstructures. Hybrid-carrageenan exhibited flocculation at both dosages. When using iota- and hybrid-carrageenan at a high dosage and kappa-carrageenan at both dosages, the gel characteristics were dominated by carrageenan-carrageenan interactions. On the other hand, the gel with a low dosage of iota-carrageenan in milk was barely fusible, indicating the presence of a true coupled network. We suggest that kappa-, iota-, and hybrid-carrageenan all interact with casein micelles but that the impact of this interaction on the total gel properties varied.

Screening for allergic respiratory disease in the general population with the ADVIA Centaur Allergy Screen Assay

BACKGROUND

In patients in whom the clinical indication for immunoglobulin E (IgE)-mediated allergic respiratory disease is weak, a single qualitative multiallergen-screening assay for IgE antibody to multiple allergen specificities may support the absence of IgE-mediated allergic respiratory disease. The aim was to investigate the diagnostic efficacy of a new multiallergen-screening assay in relation to skin prick test (SPT) reactivity and objective diagnoses of allergic respiratory disease in a general population setting.

METHODS

A total of 709 participants in a population-based study were examined by questionnaire and SPT. Serum was analysed by using a multiallergen-screening assay: the ADVIA Centaur Allergy Screen (AS) assay. The dichotomized result of the AS assay was compared with SPT reactivity, specific IgE positivity, and a clinical diagnosis of allergic rhinitis or allergic asthma defined by the presence of relevant symptoms and positive SPTs.

RESULTS

Sensitivity, specificity, and positive (PPV) and negative predictive values (NPV) of the AS against SPT reactivity were 86%, 96%, 94%, and 89%, respectively. A negative AS assay test was able to exclude allergic rhinitis and allergic asthma with a probability of more than 96% and 98% (NPV), respectively. The AS assay was able to identify more than 92% and 92% (sensitivity) of cases of allergic rhinitis and allergic asthma, respectively.

CONCLUSIONS

The AS assay proved to be a valid measure of allergic respiratory disease and may be used as a screening tool to rule out allergic respiratory disease, and as an objective measure of allergic respiratory disease in epidemiological studies.

Mucosal symptoms elicited by fragrance products in a population-based sample in relation to atopy and bronchial hyper-reactivity

BACKGROUND

Exposure to perfume and fragrance products may, in some individuals, cause symptoms from the eyes and airways. The localization, character and risk factors of such symptoms in the general population are unknown.

OBJECTIVE

To investigate both the localization and character of symptoms from the eyes and airways elicited by fragrance products, and the associations between such symptoms and skin prick test reactivity (atopy), methacholine bronchial hyper-reactivity (BHR), allergic rhinitis and asthma.

METHODS

A questionnaire on mucosal symptoms elicited by fragrance products was posted to 1189 persons who had participated in a Danish population-based study of allergic diseases in 1997/1998. The study included measurement of BHR, atopy, forced expiratory volume in 1 s (FEV1), and serum eosinophilic cationic protein (serum ECP).

RESULTS

The response rate was 79.6%. Symptoms from the eyes or airways elicited by fragrance products were reported by 42%. BHR (adjusted odds ratio 2.3, 95% confidence interval 1.5-3.5) was independently associated with symptoms from the eyes and airways elicited by fragrance products. There were no significant associations between these symptoms and atopy, FEV1 or serum ECP.

CONCLUSIONS

Mucosal symptoms from the eyes and airways were common in this population. BHR was a significant and independent predictor of these symptoms. The lack of association with atopy suggested that IgE-mediated allergic mechanisms do not play a major role in the development of these symptoms.

Airborne chemicals cause respiratory symptoms in individuals with contact allergy

Exposure to fragrance chemicals causes various eye and airway symptoms. Individuals with perfume contact allergy report these symptoms more frequently than individuals with nickel allergy or no contact allergies. However, the associations between contact allergy and respiratory symptoms elicited by airborne chemicals other than perfumes are unclear. The study aimed to investigate the association between eye and airway symptoms elicited by airborne chemicals (other than perfumes) and contact allergy in a population-based sample. A questionnaire on respiratory symptoms was posted, in 2002, to 1189 individuals who participated in 1997/1998 in a Danish population-based study of allergic diseases. Questions about eye and airway symptoms elicited by different airborne chemicals and airborne proteins were included in the questionnaire. Data from the questionnaire were compared with data on patch testing and prick testing. Having at least 1 positive patch test (adjusted odds ratio 1.7, 95% CI 1.2-2.5) was associated with the symptoms, and the odds ratio increased with the number of positive patch tests (P-value for test for trend <0.05). Bronchial hyperreactivity, female sex and psychological vulnerability were independently associated with symptoms, but no association was found between prick test reactivity to proteins and the symptoms elicited by airborne chemicals.

A link between skin and airways regarding sensitivity to fragrance products?

BACKGROUND

Exposure to volatile fragrances is commonplace and may be related to various eye and airway symptoms. Skin exposure to fragrances is known to cause perfume contact allergy and eczema, but it is unknown whether eye or airway symptoms elicited by fragrance products are associated with contact allergy or eczema.

OBJECTIVES

To investigate if eye and airway symptoms elicited by fragrance products are associated with perfume contact allergy or hand eczema in a population-based sample.

METHODS

A questionnaire on eye and airway symptoms elicited by fragrance products was mailed to 1189 individuals who had recently participated in a Danish population-based study of allergic diseases. Results from the questionnaire about localization and character of the symptoms were compared with data on patch testing and 1-year prevalence of hand eczema collected during the health examination.

RESULTS

Positive, independent and significant (P < 0.05) associations were found between eye and airway symptoms elicited by fragrance products and perfume contact allergy (adjusted odds ratios 2.0-3.7) and hand eczema (adjusted odds ratios 1.6-2.6). In further analysis, similar and consistent results were found regarding severity of the symptoms. No associations were found between nickel contact allergy and the symptoms. Female sex and psychological vulnerability were independently associated with eye and airway symptoms elicited by fragrance products, but adjustment in multivariate analysis did not change the results regarding perfume contact allergy and hand eczema.

CONCLUSIONS

Individuals with perfume contact allergy and/or hand eczema, as opposed to those without, have more frequent and more severe eye or airway symptoms after exposure to volatile fragrance products. Having hand eczema has the greatest impact on reporting eye and airway symptoms elicited by fragrance products.

The relationship of alcohol consumption to total immunoglobulin E and the development of immunoglobulin E sensitization: the Copenhagen Allergy Study

BACKGROUND

Several studies in patient populations have reported a positive association between alcohol consumption and serum total IgE. Furthermore, we have previously reported a positive association between alcohol consumption and the prevalence of skin prick test (SPT positivity) to inhalant allergens in a population-based cross-sectional study.

OBJECTIVE

To investigate the relationship of alcohol consumption to levels of serum total IgE and the development of IgE sensitization to inhalant allergens.

METHODS

In 1990, self-reported consumption of alcohol, serum total IgE, SPT positivity and specific IgE positivity to inhalant allergens were assessed in 1112 subjects, aged 15-69 years, participating in a population-based cross-sectional study in Copenhagen, Denmark. In 1998, they were invited to a follow-up and 734 were re-examined (participation rate 69.0%). Adjustment for potential confounders was performed by using multivariable regression analyses.

RESULTS

In non-atopic (specific IgE negative) subjects there was a positive association between alcohol consumption and the concentration of total IgE (P = 0.001). During the follow-up period, 45 and 33 subjects developed SPT positivity and specific IgE positivity, respectively. There was no significant association between alcohol consumption and the development of SPT positivity or specific IgE positivity. However, the risk of developing SPT positivity tended to increase with increasing consumption of alcohol (P = 0.055).

CONCLUSIONS

This epidemiological study confirms that alcohol consumption has an influence on levels of serum total IgE. A significant association between alcohol consumption and the development of IgE sensitization was not established. However, there seems to be a lack epidemiological data on this issue.

Pets in the home and the development of pet allergy in adulthood. The Copenhagen Allergy Study

BACKGROUND

The aim of the study was to investigate the association between exposure to cat and dog in the home and the development (incidence) of IgE sensitization to cat and dog.

METHODS

Participants in a population-based study of 15-69-year-olds in 1990 were invited to a follow-up in 1998. Serum IgE antibodies against common inhalant allergens was assessed in 734 subjects (participation rate 69.0%) on two occasions 8 years apart. Information about current or previous keeping of cats and dogs in the home was obtained in a questionnaire at baseline.

RESULTS

A cat in the home currently was significantly associated with the development of IgE sentisization to cat (adjusted odds ratio 8.4, 95% confidence interval (CI) 1.7-42.7). Moreover, an atopic predisposition in terms of IgE sensitization to allergens other than cat at baseline was an independent risk factor for the development of IgE sensitization to cat. A dog in the home was not significantly associated with the development of IgE sensitization to dog.

CONCLUSIONS

In this adult population, exposure to a cat in the home increased the risk of developing IgE sensitization to cat. More prospective data are needed on this issue.

Is the increase in allergic respiratory disease caused by a cohort effect?

BACKGROUND

Changes in lifestyle or environmental factors are responsible for the increasing prevalence of allergic respiratory disease. Establishing the time at which the increase began may provide a clue as to what factors possibly could have contributed to the increase. Many cross-sectional studies have shown that the prevalence of allergic sensitization decreases with increasing age. This could reflect the natural course of allergic sensitization. Alternatively, this could reflect that the increase in sensitization is caused by a cohort effect, i.e. an increase among subjects born during recent decades.

OBJECTIVE

The aim was to investigate age-specific changes in the prevalence of allergic sensitization in a cohort of adults.

METHODS

A total of 599 subjects aged 15 to 69 years participated in a cross-sectional general population study in 1990. In 1998 they were invited to a follow-up, and 64.4% (386/599) were reexamined. Serum samples obtained from the participants in 1990 and 1998 were analysed for specific IgE to six common inhalant allergens with the same assay.

RESULTS

The prevalence of allergic sensitization (specific IgE to at least one allergen) increased among subjects who were less than c. 30 years at baseline (1990), i.e. subjects born during the 1960s or later, while the prevalence was unchanged among subjects who were more than c. 30 years at baseline.

CONCLUSIONS

The results support the notion that the increasing prevalence of allergic respiratory disease is caused by a cohort effect. Thus, changes in lifestyle or environmental factors that occurred around or after 1960 may have contributed to this increase.

Tranexamic acid given intraoperatively reduces blood loss after total knee replacement: a randomized, controlled study

BACKGROUND

Extensive blood loss in total knee replacement (TKR) surgery is well known and is associated with a high transfusion rate of allogenic blood. Tranexamic acid (TXA) has been shown to reduce blood loss by 50% in this patient group, but only in cases with a perioperative loss of 1400-1800 ml. This study was performed to see if TXA offers any advantages in knee replacement surgery with blood loss at 800 ml.

METHODS

Thirty consecutive patients scheduled for TKR in spinal anesthesia with the use of a tourniquet, were randomized to TXA or non-TXA. Tranexamic acid 10 mg kg-1 was given at conclusion of surgery and again 3 h later. Blood loss was registered.

RESULTS

Total blood loss was at all times significantly lower in the TXA group compared to the non-TXA group (409.7+/-174.9 ml vs. 761.7+/-313.1 ml; P<0.001). There were no differences in coagulation parameters. No patients in the TXA group had a blood transfusion vs. 13% in the non-TXA group (NS). No complications were registered in the two groups.

CONCLUSION

We conclude that TXA significantly reduces blood loss after total knee replacement surgery.

The link between allergic rhinitis and allergic asthma: a prospective population-based study. The Copenhagen Allergy Study

BACKGROUND

It has been hypothesized that allergic rhinitis and allergic asthma are manifestations of the same disease entity. We aimed to investigate the relationship between allergic rhinitis and allergic asthma.

METHODS

Participants in a population-based study of 15-69-year-olds in 1990 were invited to a follow-up in 1998. A total of 734 subjects were examined on two occasions eight years apart. Allergic rhinitis to pollen was defined as a history of nasal symptoms on exposure to pollens and IgE specific to pollen. Allergic asthma to pollen was defined as a history of lower airway symptoms on exposure to pollens and IgE specific to pollen. Similarly, diagnoses of allergic rhinitis and allergic asthma to animals or mite were defined.

RESULTS

At follow-up, all subjects with allergic asthma to pollen (n = 52) had in addition allergic rhinitis to pollen. In the longitudinal analysis, there were a total of 28 new (incident) cases of allergic asthma to pollen. They all had allergic rhinitis to pollen at baseline, or had developed allergic rhinitis to pollen at follow-up. Accordingly, allergic rhinitis to animals and mite were ubiquitous in subjects with allergic asthma to animals and mite, respectively.

CONCLUSIONS

The results support the hypothesis that allergic rhinitis and allergic asthma are manifestations of the same disease entity.

Incidence of allergic contact sensitization in Danish adults between 1990 and 1998; the Copenhagen Allergy Study, Denmark

BACKGROUND

Studies of incidence of contact allergy in a general population have not been reported. Data from incidence studies may support and direct strategies for prevention of contact allergy and allergic contact dermatitis.

OBJECTIVE

To study the incidence of contact allergy and evaluate risk factors for developing contact allergy in an adult general population sample.

PATIENTS AND METHODS

In 1990 a random sample of 567 persons of the 15-69-year-old population living in the western part of Copenhagen County (Denmark) was patch tested in a cross-sectional study. In 1998 a follow-up study was performed. Of 540 invited, 365 (68%) were patch tested again.

RESULTS

In the follow-up study, 37 persons (12%) of the 313 patch-test-negative persons in 1990 had developed one or more positive patch tests (incident contact allergy). Twenty cases (6%) of incident nickel allergy and 25 cases (8%) of incident contact allergy to one or more haptens other than nickel were found. The data indicate that female sex, young age and ear piercing (before 1990) were risk factors for developing nickel allergy. Between 1990 and 1998 metal contact dermatitis was reported in seven women with incident nickel allergy. Six of these women had bought the eliciting item in Denmark before 1995, when vigorous control of the Danish nickel legislation was introduced.

CONCLUSIONS

We found a considerable number of incident cases of contact allergy in the adult population. The results of the study support the actions taken to restrict the use of the allergens most frequently encountered, and to increase the labelling demands to products intended for prolonged contact with the skin or a combined action.

Effect of trefoil factors on the viscoelastic properties of mucus gels

BACKGROUND

Trefoil peptides (TFFs) are expressed and secreted in a tissue-specific manner in the gastrointestinal tract. Evidence of coexpression of trefoil peptides and mucins has been demonstrated in most mucus-producing cells in the gastrointestinal tract. The expression of trefoil peptides is up-regulated in gastric ulceration and colitis. It is believed that TFF peptides interact with mucin to increase viscosity but this has never been confirmed. The aims of the present study were to elucidate the direct effect of trefoil peptides on mucus gel formation.

MATERIALS AND METHODS

The viscosity of mucin solutions was measured by means of a rotational rheometer after adding three mammalian trefoil peptides: TFF1, TFF2, and TFF3.

RESULTS

Adding TFF2 (0.3%) to the mucin solutions (8%) resulted in more than a factor 10 increase in viscosity and elasticity, and the mucin solution was transformed into a gel-like structure with serpentine-like complexes between the mucin and TFF2. The dimer form of TFF3 also increased viscosity but resulted in a spider's web-like structure. The monomer forms of TFF1 and TFF3 had very little effect on the viscosity and elasticity of the mucin solutions.

CONCLUSIONS

The addition of TFF2 to mucin solutions results in significantly increased viscosity and elasticity, under which the mucin solutions are transformed into a gel-like state. The ability of some trefoil peptides to catalyse the formation of stable mucin complexes may be one of the ways by which these peptides exert their protective and healing functions.

Can intubation harm the brain in critical care situations? A new simple technique may provide a method for controlling brain temperature

Many animal species are able to keep the brain temperature some degrees centigrade lower than the deep body temperature when exposed to environmental heat stress. The lower temperature is based on cooling of the nasal venous blood through the respiratory airflow and local counter-current transfer of heat between venous and arterial blood in the cavernous sinus-carotid artery complex. Anaesthetized, intubated animals do not have any air flow through the nasal cavities. However, when the nasal cavities were flushed with oxygen, the deep brain temperature dropped within minutes and returned to previous values when the oxygen flushing was stopped. Cooling was found in animals with a rete mirabile (pigs), and in animals without a rete (rats). If a similar cooling mechanism is present in man (no rete) under intensive care, a simple flushing of the nasal cavities with gas will protect the brain against hyperthermal damage.

Persistence of contact allergy among Danish adults: an 8-year follow-up study

In 1990, a random sample of 567 persons of the 15-69-year-old population living in the Western part of Copenhagen County, Denmark, was patch tested in a cross-sectional study. In 1998, a follow-up study was performed. Out of 540 invited, 365 (68%) were re-patch tested. In the follow-up study, the persistence of allergic contact sensitivity, defined as 1 or more positive patch tests in both surveys, was 71% (37 out of 52 subjects). Nickel allergy persisted in 79% (19 out of 24 subjects), while 60% (21 out of 35 subjects) had a positive patch test reaction to 1 or more allergens, other than nickel, in both surveys. The lowest persistence was 50% (5 out of 10 subjects) and this was found for patch test reactivity to 1 or more of the cosmetic ingredients included in the patch test series. 8 years after the baseline study had demonstrated allergic contact sensitivity, 71% of the subjects still had at least 1 positive patch test. Nickel allergy persisted in 79%. Allergen avoidance should probably be lifelong to prevent elicitation of contact dermatitis.

Factors related to allergic sensitization to aeroallergens in a cross-sectional study in adults: The Copenhagen Allergy Study

BACKGROUND

The factors underlying recent increases in the prevalence of respiratory allergy are largely unknown.

OBJECTIVE

To assess the association between allergic sensitization and several lifestyle/environmental factors.

METHODS

A cross-sectional population-based study of 15-69-year-olds in Copenhagen was carried out in 1990. The participation rate was 77.5% (1112/1435). Different lifestyle/environmental factors (explanatory variables) were defined based on questionnaire data. Dependent (outcome) variables were skin prick test (SPT) positivity or specific IgE positivity to common aeroallergens. Explanatory variables associated with outcome in univariate analysis (P < 0.25) were selected for multivariate analysis. Subsequently, a final model for each dependent variable was obtained by stepwise regression analysis (cut-off for entry/removal of variables: P < 0.1).

RESULTS

Male sex, young age, low number of siblings, a positive family history of hay fever and never smoking, were independently associated with both SPT positivity and specific IgE positivity. Furthermore, SPT positivity was positively associated with alcohol consumption (dose-response relationship only), and negatively associated with previous keeping of a dog in the household. The association between alcohol consumption and SPT positivity was mainly due to the consumption of wine and remained after adjustment for educational level. Specific IgE positivity was furthermore associated with body mass index with no apparent dose-response relationship.

CONCLUSION

Being male, young age, a positive family history of hayfever, low number of siblings and never smoking, were independently associated with allergic sensitization. In addition, the results indicated a possible relationship of alcohol consumption, body mass index and previous keeping of a dog in the household to allergic sensitization. There is a need for prospective studies of risk factors for respiratory allergy.

Secular trends of allergic asthma in Danish adults. The Copenhagen Allergy Study

Numerous studies have reported increases in asthma prevalence among children world-wide. Less is known about similar trends in adults. We aimed to investigate whether the prevalence of allergic asthma symptoms had increased in an adult general population. Two cross-sectional surveys using identical methods were carried out in 1989 and 1998. A one-page questionnaire on respiratory symptoms was mailed to random samples of 15-41-year-olds living in Copenhagen. The response rates were 86.6% (3624/4185) and 78.8% (2402/3048) in 1989 and 1998, respectively. The questionnaire was validated with specific immunoglobilin E (IgE) positivity as the reference in a random sample of responders in connection with both surveys. We found a significantly increased prevalence of subjects who reported shortness of breath on exposure to pollens (6.6% 0 s. 10.3%, odds ratio 1.61, 95% CI 1.34-1.95), furry animals (5.4% vs. 7.6%, odds ratio 1.45, 95% CI 1.17-1.79), and house dust (7.8% vs. 10.2%, odds ratio 1.35, 95% CI 1.12-1.61). The validation of these symptoms showed that the positive predictive values were reasonably stable over time, which may support that a true increase in allergic asthma has occurred. In conclusion, the prevalence of allergic asthma symptoms increased significantly in this adult general population over a 9-year period.

Smoking and the development of allergic sensitization to aeroallergens in adults: a prospective population-based study. The Copenhagen Allergy Study

BACKGROUND

Several cross-sectional population-based studies have reported a negative association between smoking and allergic sensitization to aeroallergens. In a prospective study, we investigated the association between smoking and the development (incidence) of allergic sensitization as reflected by skin prick test (SPT) positivity and specific IgE positivity.

METHODS

Participants in a population-based study of 15 69-year-olds in 1990 were invited to a follow-up in 1998. Thus, SPT positivity and specific IgE positivity to common aeroallergens were assessed in 734 subjects (participation rate: 69.0%) on two occasions 8 years apart. The effect of smoking on the development of allergic sensitization was adjusted for potential confounders such as age, sex, family history of hay fever, educational level, and total IgE.

RESULTS

During the follow-up period, 58 and 33 subjects developed SPT positivity and specific IgE positivity, respectively. The risk of developing SPT positivity (adjusted odds ratio: 0.45, 95% CI 0.21-0.98) and specific IgE positivity (adjusted odds ratio: 0.62, 95%, CI 0.26-1.49) was lower among sustained smokers than never-smokers.

CONCLUSIONS

In this adult population, sustained smoking was negatively associated with the development of allergic sensitization to aeroallergens during an 8-year follow-up. This negative association, if real, might be due to an immunosuppressive effect of smoking.

Hypotensive epidural anesthesia in total knee replacement without tourniquet: reduced blood loss and transfusion

BACKGROUND AND OBJECTIVES

[corrected] For decades, hypotensive anesthesia has been used in an attempt to reduce intraoperative blood loss. Hypotensive epidural anesthesia (HEA) is a relatively new technique in hypotensive anesthesia. Use of a tourniquet has been shown to be associated with a higher risk of cardiovascular and thromboembolic complications. The effect of HEA on blood loss and need for transfusion in total knee replacement (TKR) is not known.

METHODS

Thirty consecutive patients scheduled for TKR were randomized to HEA without tourniquet or spinal anesthesia with the use of a tourniquet (SPI). HEA was performed as an epidurally induced sympathetic block and there was an infusion of low-dose epinephrine to stabilize the circulation.

RESULTS

Intraoperative mean arterial blood pressure was 48 mm Hg (HEA) versus 83 mm Hg (SPI) (P <.001). Intraoperative blood loss was 146 mL (HEA) versus 13 mL (SPI) (P <.001). Postoperative blood loss at any time was significantly reduced in the HEA group, and total loss of blood was 1,056 mL (HEA) versus 1,826 mL (SPI) (P <.001). Half of the bleeding took place during the first 3 postoperative hours and 80% during the first 24 hours. In the HEA group, 57% of the patients went through surgery and the hospital stay without receiving blood transfusion versus 19% in the SPI group (P <.05). There was a significantly reduced amount of blood transfusion in the HEA group (193 mL) versus 775 mL in the SPI group (P <.005). No cardiopulmonary, cerebral, or renal complications were registered.

CONCLUSIONS

We conclude that HEA is a safe technique that allows TKR without a tourniquet. Compared with spinal anesthesia, the use of HEA for TKR significantly reduces blood loss and the need for blood transfusion.

Allergic contact sensitization in an adult Danish population: two cross-sectional surveys eight years apart (the Copenhagen Allergy Study)

In 1990 and 1998 15-41-year-old people were patch-tested in 2 cross-sectional studies of random samples of the population in the western part of Copenhagen County, Denmark. In 1990, 290 subjects and in 1998, 469 subjects were patch-tested. The participation rates were 69% and 51%, respectively. Contact sensitivity to one or more haptens was found in 15.9% and 18.6% in 1990 and 1998, respectively. Nickel sensitivity is still the most common contact sensitivity. The risk of contact sensitivity to the cosmetic-related haptens included in the series (formaldehyde was not included) increased significantly from 2.4% in 1990 to 5.8% in 1998 (odds ratio 2.44, 95% confidence interval 1.04-5.73). The prevalence of contact sensitivity to cosmetic-related allergens has been doubled between 1990 and 1998.

[Fractures of the pelvis--a survey of "nonunion" and "malunion" surgical results]

Nonunion (NU) and malunion (MU) of the pelvis are conditions of absent and malaligned healing of a previous pelvis fracture causing severe disabling symptoms. Reconstructive surgery of the pelvis is more demanding than treatment of the acute fracture. Ten cases of NU and/or MU of the pelvis were treated. Average time from injury to referral was 33 months. Initial treatment was conservative (seven patients), internal fixation (two patients) or combined internal and external fixation (one patient). Complaints were pain (ten patients), limp (eight patients), leg length difference (five patients) and sitting problems (seven patients).

RESULTS

All patients showed radiological union. Nine patients had less or no pain at all. All eight with a preoperative limp showed improvement or no limp after surgery. Two of five still had minor leg length difference. All seven patients with sitting problems claimed relief or complete removal of sitting problems. It is concluded that patients with severe disabling symptoms from NU and/or MU can expect relief of symptoms by late correction of the pelvic deformity.

The prevalence of skin-test-positive allergic rhinitis in Danish adults: two cross-sectional surveys 8 years apart. The Copenhagen Allergy Study

BACKGROUND

It is disputed whether increases in self-reported respiratory allergy represent a true increase or merely increased recognition. We aimed to investigate whether the prevalence of skin-prick-test (SPT)-positive allergic rhinitis had increased in an adult general population in Copenhagen, Denmark.

METHODS

Two cross-sectional surveys were carried out in 1990 and 1998. A screening questionnaire on respiratory symptoms in random samples of 15-41-year-olds preceded both surveys. Among the responders, random samples were invited to a health examination including SPT. Totals of 312 (participation rate 74.6%) and 482 (participation rate 53.4%) subjects were examined in 1990 and 1998, respectively. Diagnoses of SPT-positive allergic rhinitis were based on a history of nasal symptoms on exposure to allergens and SPT positivity to allergens.

RESULTS

The prevalence of a diagnosis of SPT-positive allergic rhinitis increased from 12.9% to 22.5% (adjusted odds ratio 1.94, 95% CI 1.30-2.90), whereas the prevalence of a positive SPT (allergen histamine wheal ratio > or = 0.5) to one or more of 10 allergens increased from 27.7% to 33.9% (adjusted odds ratio 1.47, 95% CI 1.05-2.05).

CONCLUSIONS

The prevalence of SPT-positive allergic rhinitis has increased significantly. Our findings indicate that a true increase in respiratory allergy has occurred.

Increasing prevalence of specific IgE to aeroallergens in an adult population: two cross-sectional surveys 8 years apart: the Copenhagen Allergy Study

BACKGROUND

There is evidence that the prevalence of respiratory allergy has increased in children in many countries. However, this evidence is largely based on questionnaire data, and little is known about similar trends in adults.

OBJECTIVE

We investigated whether the prevalence of specific IgE to aeroallergens had increased in an adult general population over an 8-year period.

METHODS

Two cross-sectional surveys were carried out in 1990 and 1998. A mailed screening questionnaire on respiratory symptoms sent to random samples of 15- to 41-year-old subjects living in Copenhagen (Denmark) preceded both surveys. Random samples of responders were invited to a health examination, including assessment of specific IgE to 6 common aeroallergens. Totals of 312 (74.6% of the invited subjects) and 482 (53.4% of the invited subjects) subjects were examined in 1990 and 1998, respectively. Analyses of serum samples from both surveys were performed in 1999.

RESULTS

The prevalence of specific IgE to at least one allergen increased significantly from 1990 to 1998 (26.5% vs 33.9%; odds ratio adjusted for sex, age, and season of examination, 1.63; 95% confidence interval, 1.15-2.32; P = .006). This increase remained unexplained after adjustment for changes in questionnaire variables on lifestyle and home environment. The clinical significance of this increase was underlined by a corresponding increase in the prevalence of allergic rhinitis symptoms associated with specific IgE positivity.

CONCLUSION

We found that the prevalence of specific IgE positivity to aeroallergens increased in an adult Danish general population from 1990 and 1998.

Evaluation of Göttingen minipig skin for transdermal in vitro permeation studies

The optimal skin type for in vitro permeability studies depends on the purpose of the specific transdermal study. In a number of cases, it may be advantageous to use animal skin as an alternative to human skin although they have different characteristics. Recently, Göttingen minipigs have been reported as good models in toxicological and pharmacokinetic studies of drug substances. In this paper, the potential use of skin from the Göttingen minipig is evaluated by studying three model drug substances (nicotine, salicylic acid and testosterone) through skin from humans, domestic pigs and three ages of the Göttingen minipig. An analysis of variance and a Student's t-test showed that both the skin from the Göttingen minipig and the domestic pig possessed transdermal permeabilities, which correlated with human skin and exhibited a lower intra- and intervariation. Furthermore, it was shown that permeability and variation of fluxes through skin from Göttingen minipigs were dependent on the age of the minipig and of the drug substance. It is concluded that the Göttingen minipig, like the domestic pig, is a good skin model for in vitro permeation through human skin.

Accuracy of recorded asthma deaths in Denmark in a 12-months period in 1994/95

Many studies of asthma mortality rely on official registration. The aim of this study was to evaluate the accuracy of death certificates, where asthma was coded as cause of death. In a 12-month period, medical information on all subjects with asthma officially coded as the underlying cause of death in Denmark, was obtained by reviewing hospital records, contacting general practitioners and sometimes close relatives. A panel of four pulmonologists each examined the obtained information and independently assessed the cause of death. Of a total of 218 death certificates, 39 were excluded as the cause of death could not be validated. In 16 (9%) of the subjects death from asthma was judged to be the definite cause of death and in 12 (7%) death from asthma was possible. Of 151 non-asthma deaths coded as due to asthma, 109 were judged to have suffered or died from COPD and 14 from heart disease. The accuracy of Danish death certification in asthma deaths is poor, especially in the elderly, where COPD is often classified as asthma. We conclude that the true asthma mortality in Denmark is substantially lower than officially recorded.

Salmeterol reduces the need for inhaled corticosteroid in steroid-dependent asthmatics

Previous results have demonstrated addition of long-acting beta2-adrenergic agonists to be beneficial in asthma patients already receiving inhaled corticosteroid. The purpose of this study was to determine, qualitatively as well as quantitatively, the steroid-sparing properties of salmeterol in stable asthma patients receiving maintenance inhaled corticosteroids (800-1600 microg day(-1)). In these patients, the daily dose of beclomethasone dipropionate was reduced by 200 microg each week until asthma deteriorated, with the minimal acceptable dose (MAD) being defined as the dose one step above deterioration (sensitivity period). Following this, patients received three times the MAD for 2 weeks. Patients were randomized to receive either salmeterol 50 microg twice daily or placebo and the MAD was again determined (treatment period). Forced expiratory volume in 1 sec (FEV1) was measured each week. Morning and evening peak expiratory flow (PEF), symptom score and use of bronchodilator were recorded each day. Fifteen patients received salmeterol and 19 placebo. The MAD was significantly lower in the salmeterol group compared with placebo during the treatment period (P<0.01). A 50% reduction of the MAD was achieved by more patients treated with salmeterol than placebo (P = 0.001). Salmeterol caused a significantly greater reduction in daytime symptom score and use of as-needed beta2-agoinist therapy between sensitivity and treatment periods compared with placebo (P<0.05 for both). The results demonstrate, that the addition of salmeterol to corticosteroid treatment offers a clinically relevant potential for reduction of inhaled corticosteroid dose in steroid sensitive asthmatics.

Increasing prevalence of allergic rhinitis symptoms in an adult Danish population

There is evidence that the prevalence of respiratory allergy is increasing. This is mainly based on studies in children and young adults. The aim of the study was to compare the prevalences of self-reported symptoms of respiratory allergy among Danish adults in two surveys 8 years apart. Identical questionnaires were mailed to two random general population samples in 1989 and 1997. The response rates were 86.1% (n = 3603) and 86.4% (n = 817), respectively. The sampling frame and sampling method were identical in both surveys. The changes in the prevalences of symptoms were expressed by sex- and age-adjusted odds ratios comparing 1997 to 1989. We found a significant increase in the prevalence of seasonal rhinitis symptoms (OR=1.6, 95% CI 1.4-1.9), rhinitis symptoms on exposure to pollen (OR =1.6, 95% CI 1.4-1.9), rhinitis symptoms on exposure to furry animals (odds ratio 1.6, 95% CI 1.3-2.0), rhinitis symptoms on exposure to house dust (OR = 1.3, 95% CI 1.1-1.6), and breathlessness on exposure to pollen (OR = 1.5, 95% CI 1.0-2.0). The observed increases were independent of sex and age. The questionnaire was validated in relation to allergen skin test reactivity in a subgroup of the responders to the 1989 survey. When the estimated associations between symptoms and skin test reactivity were considered, the results suggested an increase in allergy to pollen and animal dander. In conclusion, we found evidence of increased prevalence of allergic rhinitis symptoms associated with skin test reactivity.

A randomized clinical trial of alpha(1)-antitrypsin augmentation therapy

We have investigated whether restoration of the balance between neutrophil elastase and its inhibitor, alpha(1)-antitrypsin, can prevent the progression of pulmonary emphysema in patients with alpha(1)-antitrypsin deficiency. Twenty-six Danish and 30 Dutch ex-smokers with alpha(1)-antitrypsin deficiency of PI*ZZ phenotype and moderate emphysema (FEV(1) between 30% and 80% of predicted) participated in a double-blind trial of alpha(1)-antitrypsin augmentation therapy. The patients were randomized to either alpha(1)-antitrypsin (250 mg/kg) or albumin (625 mg/kg) infusions at 4-wk intervals for at least 3 yr. Self-administered spirometry performed every morning and evening at home showed no significant difference in decline of FEV(1) between treatment and placebo. Each year, the degree of emphysema was quantified by the 15th percentile point of the lung density histogram derived from computed tomography (CT). The loss of lung tissue measured by CT (mean +/- SEM) was 2.6 +/- 0.41 g/L/yr for placebo as compared with 1.5 +/- 0.41 g/L/yr for alpha(1)-antitrypsin infusion (p = 0.07). Power analysis showed that this protective effect would be significant in a similar trial with 130 patients. This is in contrast to calculations based on annual decline of FEV(1) showing that 550 patients would be needed to show a 50% reduction of annual decline. We conclude that lung density measurements by CT may facilitate future randomized clinical trials of investigational drugs for a disease in which little progress in therapy has been made in the past 30 yr.

Office spirometry: temperature conversion of volumes measured by the Vitalograph-R bellows spirometer is not necessary

The aim of the present study was to investigate the relevance of BTPS (gas at body temperature, atmospheric pressure and saturated with water vapour) conversion of volumes measured with the Vitalograph bellows spirometer. The Vitalograph bellows were tested against a MicroMedical turbine spirometer in extreme temperatures (0-37 degrees C) using a biological control to deliver expired gas at BTPS. Before testing, it was shown that the accuracy of the DairyCard turbine was stable in the relevant temperature range. In a clinical trial six patients with emphysema performed home spirometry b.i.d for 1 month using both the Vitalograph and the turbine. Both the DairyCard and the Vitalograph showed stable accuracy at extreme temperatures when results were reported without any BTPS conversion. These findings were supported by the clinical trial but the conclusions from the clinical setting were weakened by the surprising fact that domiciliary temperatures showed almost no variation. We conclude that the Vitalograph bellows, during dynamic spirometry, measures expired volume at conditions closer to BTPS (than to ATPS) gas at ambient temperature, atmospheric pressure and saturated with water vapour). The use of the BTPS correction based on ambient temperature seems unjustified at office temperatures close to 23 degrees C and at extreme temperatures the conversion of volume will introduce significant over or underestimation.

Complexation graft copolymer networks: swelling properties, calcium binding and proteolytic enzyme inhibition

Graft copolymer networks of poly(methacrylic acid-g-ethylene glycol) were prepared by free radical solution UV-polymerization of methacrylic acid (MAA) and poly(ethylene glycol) monomethacrylate. Dynamic swelling studies indicated that complexation/decomplexation processes occurred due to hydrogen bonding between the carboxylic groups of the poly(methacrylic acid) (PMAA) and the ether groups of poly(ethylene glycol) (PEG). The effects of copolymer composition, graft chain molecular weight, environmental pH and ion content on network structure and gel behavior were studied. The largest change in swelling ratio and mesh size of the gel structure was observed in gels containing the highest content of PEG and the longest molecular weight PEG grafts. Complexation was greatest in hydrogels containing the longest PEG grafts and equimolar amounts of MAA and PEG. The swelling was much less pronounced in the presence of calcium chloride compared to sodium chloride which could be attributed to the complexation of calcium of the carboxylic groups in the polymer. The copolymers showed significant but less binding of calcium compared to poly(acrylates) like Carbopol 934P and polycarbophil. The P(MAA-g-EG) copolymers inhibited trypsin but to a lesser extent than the known protease inhibitors Carbopol 934P and polycarbophil. Results suggest that P(MAA-g-EG) copolymers are good drug delivery carrier candidates due to their pH-sensitive and controllable swelling behavior. Additionally, they possess some protease inhibition effect along with their bioadhesive properties which make them promising carriers for peptides or proteins.

Long-range correlations of serial FEV1 measurements in emphysematous patients and normal subjects

In obstructive lung disease the annual change in lung function is usually estimated from serial measurements of forced expiratory volume in 1 s (FEV1). Frequent measurements in each patient may not improve this estimate because data are not statistically independent; i.e., the measurements are autocorrelated. The purpose of this study was to describe the correlation structure in time series of FEV1 measurements. Nineteen patients with severe alpha1-antitrypsin deficiency (phenotype PiZ) and moderate to severe emphysema and two subjects with normal lungs were followed for several years with daily self-administered spirometry. FEV1 measurements fulfilling standard criteria were detrended, and the autocorrelation profile and the power spectrum were calculated. On average the subjects were followed for >3 yr and performed >1,000 acceptable spirometries. The autocorrelation of FEV1 measurements in the emphysematous patients was approximately 0.35 for short intervals and decreased almost exponentially with a half time of 38 days. Between 3 and 4 mo, the autocorrelation function became negative. It reached a minimum of -0.1 at approximately 8 mo and then increased toward zero over the following 12 mo. The autocorrelation function in the two normal subjects showed a similar pattern, but with a faster decay toward zero. In the patients, the power spectrum had a peak at 1 cycle/wk and showed a 1/f pattern, where f is frequency, with a slope of -0.88 at lower frequencies. We conclude that serial spirometric measurements show long-range correlations. The practical implication is that FEV1 need not be measured more often than once every 3 mo in studies of the long-term trends in lung function.

A rheological assessment of the nature of interactions between mucoadhesive polymers and a homogenised mucus gel

The ability of mucoadhesive materials to produce a large increase in the resistance to deformation when incorporated into a mucus gel, relative to when the mucus gel and test materials are evaluated separately at the same concentration, has been reported in several previous studies. It has been proposed that this phenomenon, termed rheological synergism, can be used as a measure of the strength of the mucoadhesive interaction. This study investigated the interactions between four putative mucoadhesive polymers (Noveon, Pemulen TR-2, carageenan and sodium carboxymethylcellulose) and a homogenised mucus gel, using dynamic oscillatory rheology. It was shown that, with the exception of sodium carboxymethylcellulose, incorporating a mucoadhesive polymer into a mucus gel produces rheological behaviour indicative of a weakly cross-linked gel network, which suggested a structure containing physical chain entanglements and non-covalent (probably hydrogen) bonds. Optimum gel strengthening occurred in a weakly acidic environment, suggesting an optimum conformation and degree of ionisation of the polymer and mucus molecules. Subsequent work suggested that the macromolecular interactions between polymer and mucus are sensitive to temperature, with the dynamic moduli decreasing with increasing temperature, further indicating bonding of a non-covalent nature. This work provide further evidence that rheological methods can be used as a tool to evaluate the interactions between a mucoadhesive macromolecule and a mucus gel. It also adds to the perception that molecular interpenetration may be an important factor in mucoadhesion by strengthening the mucus in the mucoadhesive/mucosal interfacial layer.

Clinical magnetic resonance imaging and arthroscopic findings in knees: a comparative prospective study of meniscus anterior cruciate ligament and cartilage lesions

We compared the diagnostic and predictive value of magnetic resonance imaging (MRI) and clinical findings with arthroscopy in 61 knees in a prospective study. In meniscal tears, the accuracy and positive predictive value of MRI was found to be nearly twice that of clinical examination. The sensitivity, specificity, and negative predictive value of MRI were comparable to the figures found in other studies. We recommend MRI as a clarifying diagnostic tool when a clinical examination indicates a lesion of the meniscus. In our study, the clinical relevance of MRI in anterior cruciate ligament lesions and especially in cartilage lesions was more doubtful. The combination of clinical and MRI findings would reduce the number of blank arthroscopies to 5%. MRI is a valuable diagnostic tool in planning the type of anesthesia and treatment, and could significantly reduce the need for a second arthroscopy.

A rheological examination of the mucoadhesive/mucus interaction: the effect of mucoadhesive type and concentration

The ability of mucoadhesive polymers to produce a large increase in the resistance to deformation when incorporated into a mucus gel, relative to when the mucus gel and test materials are evaluated separately at the same concentrations, has been reported in several previous studies. It has been proposed that this phenomenon, termed rheological synergism, can be used as a measure of the strength of the mucoadhesive interaction. In this investigation rheological synergism was investigated for a large range of putative mucoadhesive gels by dynamic oscillatory rheology. Changes in the storage modulus (G'), loss modulus (G"), and loss tangent (tan-delta) were found and the relative rheological synergism calculated. Rheological synergism was evident for a range of materials with known mucoadhesive properties giving behaviour between that of strongly cross-linked polymers gels and a physically entangled system. This effect was most marked with materials known to be of high mucoadhesive strength even when fully hydrated. Hence, polymers like sodium carboxymethylcellulose and high molecular weight poly(ethylene oxide) showed limited rheological synergism. When the effect of mucoadhesive concentration was investigated, relative rheological synergism occurred within a limited concentration range only, the values of which varied between materials. It was concluded that macromolecules possessing numerous hydrogen bond-forming groups and an open expanded network in the test environment gave pronounced rheological synergism, and the relevance of this to mucoadhesion studies will be investigated in further work. This study also confirmed the advantages of dynamic oscillatory rheology over simple viscosity measurement in the study of these systems.

MR diffusion imaging of human intracranial tumours

We used MRI for in vivo measurement of brain water self-diffusion in patients with intracranial tumours. The study included 28 patients (12 with high-grade and 3 with low-grade gliomas, 7 with metastases, 5 with meningiomas and 1 with a cerebral abscess). Apparent diffusion coefficients (ADC) were calculated in a single axial slice through the tumours, the sequence was sensitive to diffusion along the cephalocaudal axis. Our main finding was that ADC in contrast-enhancing areas within cerebral metastases was statistically significantly higher than ADC in contrast-enhancing areas in high-grade gliomas (P < or = 0.05). Furthermore, the ADC in oedema surrounding metastases were statistically significantly higher the ADC in oedema around high-grade gliomas (P < or = 0.02). The ADC in patients with meningiomas did not differ significantly from those seen with high-grade gliomas or cerebral metastases. The highest ADC were found within cystic or necrotic tumour areas. In one patient with a cerebral abscess, suspected of having a high-grade glioma, the ADC was similar to that in high-grade gliomas. The finding of higher ADC in cerebral metastases than in high-grade gliomas may be helpful in trying to distinguish between these tumours preoperatively; it suggests increased free extracellular and/or intracellular water fraction in cerebral metastases. The method seems to hold potential for further noninvasive characterisation of intracranial tumours.

Neurosurgery for trigeminal neuralgia: comparison of alcohol block, neurectomy, and radiofrequency coagulation

OBJECTIVES

We wished to assess the present condition of patients previously treated with a neurosurgical procedure or procedures for trigeminal neuralgia (TN) in 383 patients treated between 1976 and 1991, for TN at the Department of Neurosurgery, Hvidovre Hospital. Of these, 67 were lost to follow-up. The latest surgical intervention performed was radiofrequency coagulation (RFC) (64%), neurectomy (18%), alcohol block (16%), trigeminal tractotomy (1%), and microvascular decompression (1%); 72% of patients underwent only one neurosurgical procedure.

METHODS

Questionnaires were sent to 316 patients treated neurosurgically for TN during the 16-year period; 288 (91%) patients responded. The follow-up period varied from 1 to 16 years (mean 8 years). Outcome measures were effect of RFC, neurectomy, and alcohol block; present pain conditions; and sequelae.

RESULTS

After RFC, neurectomy, and alcohol block, 83, 51, and 42% of patients, respectively, experienced a pain-free postoperative period; 49, 78, and 84% of these patients had recurrence of pain. At present, 49, 17, and 18% are pain-free and 33, 21, and 36% now have less pain than they did preoperatively. Temporary or permanent analgesics for facial pain were required in 41, 72, and 69% of the patients. Sequelae were described by 65, 57, and 49% of the patients. The four most common sequelae were hypoesthesia, paresthesia, eye complaints, and dysesthesia.

CONCLUSION

If relevant pharmacotherapy has been tried without benefit, RFC may still be considered as a treatment for TN.

Long-term performance of a hand held spirometer

BACKGROUND

A study was undertaken to test the long term performance of a small hand held spirometer for self-administered serial spirometric testing.

METHODS

Thirty turbine pocket spirometers (MicroMedical DiaryCard) were used in a clinical trial on 22 emphysematous patients with severe alpha 1-antitrypsin deficiency. The spirometers were able to store the date, time, forced expiratory volume in one second (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF), and flow-volume loop for each blow. Every four weeks when the patients came for alpha 1-antitrypsin infusions the performance of their spirometer was checked before and after retrieval of the data from the spirometer. Calibration checks were threefold and included volume calibration with a 1.0 litre and 3.0 litre syringe, and flow calibration with a decompression calibrator.

RESULTS

After two years of study the mean number of spirometric recordings performed per spirometer was 693 (range 237-1178), and the mean number of calibration checks was 33 (range 2-57). The coefficient of variation of the calibration signal was 1-2% for syringes and 0.5-1% for the decompression calibrator. The bearings of one turbine exhibited excessive friction after 17 months. None of the other 29 instruments showed drift, and a general drift of all spirometers towards larger or smaller readings could not be shown. However, unforeseen problems in the stability of the calibrating devices were observed.

CONCLUSIONS

The small hand held turbine spirometers are suitable for long term patient-administered serial spirometric testing. The two year durability is acceptable and the long term reproducibility excellent.

Patient-administered sequential spirometry in healthy volunteers and patients with alpha 1-antitrypsin deficiency

The launching of cheap, pocket-sized spirometers, with data storage capability, has made patient-administered sequential spirometry (PASS) an attractive method of monitoring ventilatory capacity. At present, little information is available on the quality of PASS, compared to laboratory spirometry. The aim of this study was to investigate whether patients could perform PASS without loss of reliability and reproducibility as compared with traditional laboratory spirometry. Ten healthy volunteers performed spirometry for 1 month and 10 emphysematous patients with alpha 1-antitrypsin deficiency (type PiZ) performed spirometry twice daily for up to 2 yr. To fulfil Good Clinical Practice criteria on full data documentation, a traditional direct recording spirometer, the Vitalograph R-model, was used. A decompression device was used for calibration and a 3.8% annual drift in volume registration was noted. This drift was largest for the first year. After training, all patients were able to perform unsupervised spirometry, producing technically correct forced expiratory curves. Reproducibility of FEV1 and FVC obtained by PASS was found to be as good as for laboratory spirometry. After adjustment for the diurnal variation, the residual variation of FEV1 was 2.5% (range 1.6-4.2%) for healthy volunteers and 5.6% (range 4.2-7.7%) for emphysematous patients. Forced vital capacity showed the same pattern. In conclusion, PASS is possible in highly motivated individuals without loss of reliability and reproducibility when compared to laboratory spirometry.

Challenge interval determines tachyphylaxis to aerosolized LTD4

Leukotrienes (LK) play an important role in the inflammatory response found in the asthmatic airway and it is therefore of interest to explore the clinical value of agents which can either block the effect or inhibit the synthesis of leukotrienes. If tachyphylaxis does not develop, repeated LTD4 challenges can be used for dose ranging studies. Tachyphylaxis has been observed when LTD4 challenge intervals are kept below 1 h, but the effect of prolonging the interval is uncertain. The aim of this study was therefore to investigate the interval between LTD4 challenges necessary to avoid development of tachyphylaxis. Ten stable adult asthmatics with moderate asthma were challenged seven times: a screening day to secure responsiveness to LTD4, two challenges on three separate days with an interval of 2, 4 and 6 h, respectively. No significant differences between mean PC20-LTD4 values (P > 0.5) was found. It was concluded that tachyphylaxis to repeated LTD4 challenges of asthmatics does not develop when challenge intervals are prolonged above 2 h.

Chronic asthma and chiropractic spinal manipulation: a randomized clinical trial

The purpose of this randomized patient- and observer-blinded cross-over trial was to evaluate the efficacy of chiropractic treatment in the management of chronic asthma when combined with pharmaceutical maintenance therapy. The trial was conducted at the National University Hospital's Out-patient Clinic in Copenhagen, Denmark. Thirty-one patients aged 18-44 years participated, all suffering from chronic asthma controlled by bronchodilators and/or inhaled steroids. Patients, or who had received chiropractic treatment for asthma within the last 5 years, who received oral steroids and immunotherapy, were not eligible. Patients were randomized to receive either active chiropractic spinal manipulative treatment or sham chiropractic spinal manipulative treatment twice weekly for 4 weeks, and then crossed over to the alternative treatment for another 4 weeks. Both phases were preceded and followed by a 2-week period without chiropractic treatment. The main outcome measurements were forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), daily use of inhaled bronchodilators, patient-rated asthma severity and non-specific bronchial reactivity (n-BR). Using the cross-over analysis, no clinically important or statistically significant differences were found between the active and sham chiropractic interventions on any of the main or secondary outcome measures. Objective lung function did not change during the study, but over the course of the study, non-specific bronchial hyperreactivity (n-BR) improved by 36% (P = 0.01) and patient-rated asthma severity decreased by 34% (P = 0.0002) compared with the baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)