Lung function measurements in children - copsac

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onciolitis. There is an increasing recognition that other viruses (e.g. rhinovirus) are as common as RSV causing bronciolitis in young children (142, 169-171). A recent prospective, population-based cohort study examined the associations between hospitalization for RSV infection and invasive pneumococcal disease in Danish children < 2 years. The study found that invasive pneumococcal disease did not increase the risk of RSV hospitalization but recent hospitalization for RSV increased the risk of invasive pneumococcal disease (168). On the other hand a previous study from the COPSAC cohort showed that neonates colonized in the hypopharyngeal region with S. pneumonia, H. influenza, or M. catarrharlis, or with a combination, were at increased risk for recurrent wheeze and asthma early in life (126). One may consider co-infections with other viral or bacterial infections responsible for different response to RSV infection and the development of asthma (90). This may argue against the “hygiene hypothesis”, where the absence of microbial stimulation postnatal results in a skewed Th-1/Th-2 balance, but the rate of transition from fetal to adult-like Th-1 cells is much slower in those with atopic parents (88). So the Th-1/Th-2 balance results from complex interactions between genetic background and environmental influences during infancy. 52
Conclusion and future perspectives Study I In conclusion, using a biological control we revealed errors in the accuracy of sRaw measurements at some centers despite normal calibration of the mechanical components. This study highlights the need for the development of equipment allowing control of the actual resistance measurements and not only some of its mechanical components. When software versions are upgraded with possible changes in algorithms, this could result in an undiscovered difference in sRaw value, unless the company provides a correction factor. A portable mechanical lung model analogue is needed for quality control of whole-body plethysmograph in preschool children. In addition, quality assurance could be optimized by developing the software to determine the best breath curves from algorithms as flow and respiratory rates or encourage the child (with animated bio-feedback) to breath with optimal respiratory rates and flow. This could be a commercial responsibility or be developed in collaboration with a technical department. Until such equipment becomes available the only option is to use healthy subjects to assure that the absolute value measured is similar to the normative values reported in this and a previous report of healthy young children. If the measured baseline sRaw value is in the normal range and the clinician still suspects asthma, regardless of equipment type or software version, we recommend to measure bronchial hyperreactivity (≥25% increase in sRaw) (18) or bronchodilator responsiveness with a short-acting beta2-agonist (≥25% decrease in sRaw) (38); these tests can contribute to the asthma diagnose (11). Furthermore, the sRaw method has a good short and long term repeatability between occasions in stable asthmatics as previously presented by Klug et al. (1997) (15, 50), which is useful for the clinician in assessing asthma control for the individual patient. We have examined the agreement of sRaw values between 6 centers using same equipment and produced a new set of normative data. It is uncertain if the normative values can be applied on other commercial whole-body plethysmographs. Our study showed a variation between the different centers and one can speculate if there exists a true reference interval when measurement of sRaw values seems to depend on the equipment. Preliminary results suggest that there are differences in sRaw values measured between different commercial whole-body plethysmographs. However, 53
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Lung function measurements in child
Page 4 and 5: Contents Acknowledgements .........
Page 6 and 7: Acknowledgements The thesis was wri
Page 8 and 9: Introduction Symptoms of chronic re
Page 10 and 11: pulmonary function test obtained by
Page 12 and 13: I. Accuracy of Wholebody Plethysmog
Page 14 and 15: Methods Designs Study I: Six center
Page 16 and 17: "Loops" on the screen showed the re
Page 18 and 19: We included age in the analysis of
Page 20 and 21: Normative data (study I) Mean sRaw
Page 22 and 23: Additional results sRaw measurement
Page 24 and 25: After correcting the factory settin
Page 26 and 27: Normative data In the second part o
Page 28 and 29: II. -III. Lung function measurement
Page 30 and 31: of a diagnosis of asthma: Frequent
Page 32 and 33: Figure 8: Familial predisposition t
Page 34 and 35: Total twins 12.349 twin pairs Born
Page 36 and 37: Methods Designs Study II: Hospital
Page 38 and 39: Children less than 7 years were tes
Page 40 and 41: Ethics The two studies were approve
Page 42 and 43: FEV 0.5 (ml) Table 4: Baseline char
Page 44 and 45: lung symptoms, 19% said it was the
Page 46 and 47: symptoms in response to verified RS
Page 48 and 49: epigenetic factors. Acute environme
Page 50 and 51: detection changes in lung function
Page 52 and 53: that small airways were not the dis
Page 56 and 57: further studies are needed to inves
Page 58 and 59: Summary The Ph.D. thesis is based o
Page 60 and 61: Danish summary (Dansk resumé) Denn
Page 62 and 63: References Reference List (1) Lum S
Page 64 and 65: (25) Aurora P, Gustafsson P, Bush A
Page 66 and 67: (50) Klug B, Bisgaard H. Repeatabil
Page 68 and 69: (76) Meissner HC. Economic impact o
Page 70 and 71: (101) Young S, Arnott J, O'Keeffe P
Page 72 and 73: (125) Bisgaard H, Hermansen MN, Lol
Page 74 and 75: (151) Walton RP, Johnston SL. Role
Page 76 and 77: disease in otherwise healthy infant
Page 78 and 79: changes in asthma control. Am J Res
Page 81: Paper I
Page 84 and 85: CHEST Original Research Accuracy of
Page 86 and 87: Figure 1. Center agreement study: l
Page 88 and 89: observer as well as a common observ
Page 90 and 91: sRaw (kPa*s) Figure 1 Online: Cente
Page 93 and 94: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Page 95 and 96: 54 55 56 57 INTRODUCTION Respirator
Page 97 and 98: 97 98 99 100 Lung function test Chi
Page 99 and 100: 141 142 143 144 Mean gestational ag
Page 101 and 102: 186 187 188 189 190 The discordant
Page 103 and 104: 232 233 234 235 236 237 viruses and
Page 105 and 106:
278 ACKNOWLEDGMENTS 279 280 281 282
Page 107 and 108:
335 336 (21) Bisgaard H, Nielsen KG
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394 395 396 (42) Wu P, Dupont WD, G
Page 111 and 112:
455 456 457 (64) Bisgaard H, Herman
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488 489 Table 1: Comparison of clin
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Paper III
Page 118 and 119:
Abstract Background: Two-three perc
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RA 08 TSM 133; Respiratory Care Cen
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prospectively if baseline lung func
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who do not develop RSV bronchioliti
Page 126 and 127:
Acknowledgements We thank all the c
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(24) ATS/ERS statement: raised volu
Page 130 and 131:
(53) Stein RT, Sherrill D, Morgan W
Page 132 and 133:
Figure 1: Flow chart COPSAC cohort
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