Consensus statement for inert gas washout measurement using multiple- and single- breath tests

Inert gas washout tests, performed using the single- or multiple-breath washout technique, were first described over 60 years ago. As measures of ventilation distribution inhomogeneity, they offer complementary information to standard lung function tests, such as spirometry, as well as improved feasibility across wider age ranges and improved sensitivity in the detection of early lung damage. These benefits have led to a resurgence of interest in these techniques from manufacturers, clinicians and researchers, yet detailed guidelines for washout equipment specifications, test performance and analysis are lacking. This manuscript provides recommendations about these aspects, applicable to both the paediatric and adult testing environment, whilst outlining the important principles that are essential for the reader to understand. These recommendations are evidence based, where possible, but in many places represent expert opinion from a working group with a large collective experience in the techniques discussed. Finally, the important issues that remain unanswered are highlighted. By addressing these important issues and directing future research, the hope is to facilitate the incorporation of these promising tests into routine clinical practice.

A realistic validation study of a new nitrogen multiple-breath washout system

BACKGROUND

For reliable assessment of ventilation inhomogeneity, multiple-breath washout (MBW) systems should be realistically validated. We describe a new lung model for in vitro validation under physiological conditions and the assessment of a new nitrogen (N(2))MBW system.

METHODS

The N(2)MBW setup indirectly measures the N(2) fraction (F(N2)) from main-stream carbon dioxide (CO(2)) and side-stream oxygen (O(2)) signals: F(N2) = 1-F(O2)-F(CO2)-F(Argon). For in vitro N(2)MBW, a double chamber plastic lung model was filled with water, heated to 37°C, and ventilated at various lung volumes, respiratory rates, and F(CO2). In vivo N(2)MBW was undertaken in triplets on two occasions in 30 healthy adults. Primary N(2)MBW outcome was functional residual capacity (FRC). We assessed in vitro error (√[difference](2)) between measured and model FRC (100-4174 mL), and error between tests of in vivo FRC, lung clearance index (LCI), and normalized phase III slope indices (S(acin) and S(cond)).

RESULTS

The model generated 145 FRCs under BTPS conditions and various breathing patterns. Mean (SD) error was 2.3 (1.7)%. In 500 to 4174 mL FRCs, 121 (98%) of FRCs were within 5%. In 100 to 400 mL FRCs, the error was better than 7%. In vivo FRC error between tests was 10.1 (8.2)%. LCI was the most reproducible ventilation inhomogeneity index.

CONCLUSION

The lung model generates lung volumes under the conditions encountered during clinical MBW testing and enables realistic validation of MBW systems. The new N(2)MBW system reliably measures lung volumes and delivers reproducible LCI values.

Normative data for lung function and exhaled nitric oxide in unsedated healthy infants

Despite association with lung growth and long-term respiratory morbidity, there is a lack of normative lung function data for unsedated infants conforming to latest European Respiratory Society/American Thoracic Society standards. Lung function was measured using an ultrasonic flow meter in 342 unsedated, healthy, term-born infants at a mean ± sd age of 5.1 ± 0.8 weeks during natural sleep according to the latest standards. Tidal breathing flow-volume loops (TBFVL) and exhaled nitric oxide (eNO) measurements were obtained from 100 regular breaths. We aimed for three acceptable measurements for multiple-breath washout and 5-10 acceptable interruption resistance (R(int)) measurements. Acceptable measurements were obtained in ≤ 285 infants with high variability. Mean values were 7.48 mL·kg⁻¹ (95% limits of agreement 4.95-10.0 mL·kg⁻¹) for tidal volume, 14.3 ppb (2.6-26.1 ppb) for eNO, 23.9 mL·kg⁻¹ (16.0-31.8 mL·kg⁻¹) for functional residual capacity, 6.75 (5.63-7.87) for lung clearance index and 3.78 kPa·s·L⁻¹ (1.14-6.42 kPa·s·L⁻¹) for R(int). In males, TBFVL outcomes were associated with anthropometric parameters and in females, with maternal smoking during pregnancy, maternal asthma and Caesarean section. This large normative data set in unsedated infants offers reference values for future research and particularly for studies where sedation may put infants at risk. Furthermore, it highlights the impact of maternal and environmental risk factors on neonatal lung function.

Cysteinyl-leukotrienes in nasal lavage fluid in children with asthma

The aim of this study was to investigate repeatability of cysteinyl-leukotrienes (cys-LT) measurements in nasal lavage fluid (NLF) and to determine if cys-LT levels in NLF are related to asthma severity in children. As a second outcome, we investigated if cys-LT in NLF reflect lower airway inflammation as assessed by exhaled NO measurement. To assess the repeatability of cys-LT measurements, two NLF samples were obtained from eight healthy controls 24 h apart. Sixty-nine asthmatic children (mean age; range: 12.8; 7.3-17.7 yr), which were grouped according to asthma severity were studied cross-sectionally on one occasion. Cys-LT in NLF were analyzed using a specific enzyme immunoassay, exhaled NO, and pulmonary function parameters were measured. The coefficient of repeatability for the repeated cys-LT measurements was 1.45 pg/ml. Cys-LT levels in NLF differed significantly between asthma severity groups (p < 0.001): mild intermittent: [median (IQR)] 6.88 pg/ml (2.00-27.87); mild persistent: 21.09 pg/ml (4.50-84.67); and moderate persistent asthmatics: 36.41 pg/ml (11.03-118.40). Concentration of cys-LT in NLF and exhaled NO was positively correlated (r = 0.85; p < 0.001). In conclusion, concentration of cys-LT in NLF correlates with asthma severity in children and is related to lower airway inflammation.

Longitudinal monitoring of pediatric cystic fibrosis lung disease using nitrite in exhaled breath condensate

Cystic fibrosis (CF) lung disease is characterized by airway inflammation and airway infection. Nitrites in exhaled breath condensate (EBC-NO(2)(-)) have been shown to be increased in children and adults with CF compared to healthy controls suggesting its use as a measure of airway inflammation. This longitudinal study aimed to evaluate if repeated measurements of EBC-NO(2)(-) are helpful in monitoring CF lung disease activity in children. Thirty-two children with mild CF lung disease (age 10.6 +/- 3.3 years) were recruited in two study centers. Follow-up visits occurred every 3 months over a period of 1 year with a total of five visits. Each visit included a clinical assessment incorporating a modified Shwachman-Kulczycki (SK) score, spirometry, an oropharyngeal swab, or sputum sample for bacterial analysis and an EBC sample analyzed for NO(2)(-) using a spectrophotometric assay. Furthermore at the first and the last visit a chest radiograph was done and scored (Chrispin-Norman (CN) score). There was no correlation of EBC-NO(2)(-) and parameters of spirometry, SK-score, or CN-score. Furthermore, increased EBC-NO(2)(-) levels did not predict subsequent pulmonary exacerbations. We conclude that repeated measurements of EBC-NO(2)(-) are not helpful in the longitudinal monitoring of mild CF lung disease in children.

Predicting factors for severity of rheumatoid arthritis: a prospective multicenter cohort study of 172 patients over 3 years

Rheumatoid arthritis may take an unfavourable course leading to rapid functional decline in a certain percentage of patients. Early identification of these patients is desirable. The aim of this study was to evaluate clinical and laboratory parameters for their value in the prediction of bad outcome. A total of 172 patients with early arthritis were followed for 3 years. Higher initial values for erythrocyte sedimentation rate, IgG and IgM rheumatoid factor, serum concentration of cartilage oligomeric matrix protein, Health Assessment Questionnaire score, Larsen score of feet, disease activity score, and swollen and tender joint count predicted worse outcome. An association with the presence of IgA rheumatoid factor or anti-cyclic-citrullinated peptide could not be established. We conclude that prognosis in an individual with rheumatoid arthritis depends on many factors. The determination of independent prognostic factors for progression of rheumatoid arthritis is a valuable tool in early arthritis to select patients for more aggressive therapy.

Death in correctional facilities: opportunities for automated external defibrillation

BACKGROUND

Death due to cardiovascular disease occurs more frequently in prisons than the national average. Due to close surveillance 24 h/day, the ability to reach the patient within 3 min and time consuming access for the EMS crews, it was hypothesised that the deployment of automated external defibrillators (AEDs) might make improvements regarding Call-to-the-First-AED-Prompt (CTP) interval and formed the aim of this study.

METHODS

Our investigation was analysed on an intention to treat basis and conducted in a prospective, open and observational design. As the primary outcome, the CTP-intervals were compared to the arrival intervals of the EMS. As a secondary outcome, an analysis of all deceased inmates was described.

RESULTS

The average daily population of inmates in Austrian correctional facilities is 7714. During a period of 13 months, 10 instances in which an AED was activated and electrodes attached to a collapsed inmate, were reported. The CTP-interval (median+/-S.D.) was 2.3+/-1.6 S.D. min. It took the EMS 10.0+/-4.3 S.D. min. to arrive at the patient's side. Four out of 10 cases of cardiac arrest occurred due to myocardial infarction. Of 39 deceased inmates, a post mortem examination was completed in 34 cases. In 13 cases, cardiovascular disease was the cause of death.

DISCUSSION

The main finding was a four-fold reduction of the CTP-interval. This fact indicates the potential improvements which could be achieved with the deployment of AEDs. Our secondary objective revealed that death due to cardiovascular disease was found in a high proportion and could be considered to be a strong incentive to initiate programmes to counter cardiovascular death in prison.

Automated external defibrillators do not recommend false positive shocks under the influence of electromagnetic fields present at public locations

Electromagnetic fields (EMF) reduce the signal quality of electrocardiograms and may lead to the misinterpretation by automated external defibrillators (AED). We designed this investigation as a prospective study, with a randomized sequence of AED applications on healthy volunteers. We chose busy public places where public access defibrillation was possible as test locations. Strong EMF were sought and found at train stations next to accelerating and decelerating trains. The primary outcome variable was the absolute number of shocks advised in the presence of sinus rhythm by five commonly used AED in Austria. For data analysis, the statistician was blinded in regard to the AED models tested. Data analysis was based on a per protocol evaluation. Of 390 tests run, 0 cases of false positive results occurred (95% CI: 0-0.77). AED can be regarded as safe, even with the interference of EMF present at train stations.

Influence of electromagnetic fields on function of automated external defibrillators

OBJECTIVES

In this study, the authors tested whether electromagnetic interference (EMI) is able to impair correct electrocardiogram analysis and produce false-positive shock advice from automated external defibrillators (AEDs) when the true rhythm is sinus.

METHODS

Nineteen healthy subjects were used to test five AEDs available on the Austrian market in a prospective, open, and sequence-randomized study. The primary outcome variable was the absolute number of shocks advised in the presence of EMI. The secondary outcome was the number of impaired analyses caused by incorrectly detected patient movements or electrode failure.

RESULTS

Of 760 tests run, 18 (2.37%) cases of false-positive results occurred, and two of five AEDs recommended shocks in the presence of sinus rhythm. Of 760 tests run, no electrode failures occurred. There were 27 occurrences (3.55%) of motion detected by an AED in the presence of strong electromagnetic fields.

CONCLUSIONS

AED models differ in their response to EMI; it may be useful to consider specific safety requirements for areas with such fields present. Working personnel and emergency medical services staff should be informed about potential risks and the possible need for patient evacuation before AEDs are attached and shock recommendations are followed.

[Treatment of osteoarthritis of the knee joint. Efficacy and tolerance to acemetacin slow release in comparison to celecoxib]

OBJECTIVE

The aim of this trial was to compare acemetacin (ACE) with celecoxib (CEL) in terms of tolerability and efficacy in the treatment of osteoarthritis of the knee joint.

METHODS

A total of 105 patients (26-64 years old) suffering from primary osteoarthritis (OA) of the knee were enrolled in this international, multicenter, randomized, double blind controlled trial. Fifty three patients were given ACE and 52 CEL. They were treated with either 90 mg bid of slow release ACE or 200 mg bid of CEL for 6 weeks. Additional gastroprotective therapy was not provided. Tolerability was assessed by physical examination, laboratory tests, vital signs and reports of side effects, as well as by patient and physician global assessments. Efficacy parameters comprised pain assessment by visual analogue scale (VAS) and ordinal scale, WOMAC, SF-36 and patient and physician global impressions of efficacy. In addition, acetaminophen consumption was recorded.

RESULTS

In 21 ACE (39.6%) and 19 CEL patients (36.5%), the number of side effects totaled 56 (ACE n=29; CEL n=27) (ns). Mean pain reduction at week 6 was highly significant ( P<0.0001) in both groups and amounted to 38.7 mm (+/-20.3) in the ACE group and to 35.1 mm (+/-18.7) in the CEL group (ns). Very similar results were seen with respect to the other efficacy parameters.

CONCLUSION

ACE is not inferior to CEL for the short-term treatment of knee OA in terms of tolerability and efficacy.