Assessment of passive respiratory mechanics in infants: double<i>versus</i>single occlusion?

Goetz, Iris; Hoo, Ah‐Fong; Lum, Sooky; Stocks, Janet

doi:10.1183/09031936.01.17304490

Cited by 14 publications

(15 citation statements)

References 19 publications

(18 reference statements)

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“…The Jaeger BabyBody device (V.4.65; Care Fusion, San Diego, California, USA) was used to measure plethysmographic FRC (FRC pleth ),26 27 total respiratory compliance (C rs ) and resistance (R rs ),28 forced expiratory volume (FEV 0.5 ), forced vital capacity (FVC) and forced expiratory flows (FEF 75 , FEF 25–75 ) from an inflation pressure of 30 cmH 2 O using the raised volume technique 19. Measurements were always performed in that order.…”

Section: Methodsmentioning

confidence: 99%

Lung function is abnormal in 3-month-old infants with cystic fibrosis diagnosed by newborn screening

Hoo

Thia²,

Bush

et al. 2012

Thorax

139

141

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Background Long-term benefits of newborn screening (NBS) for cystic fibrosis (CF) have been established with respect to nutritional status, but effects on pulmonary health remain unclear. Hypothesis With early diagnosis and commencement of standardised treatment, lung function at w3 months of age is normal in NBS infants with CF. Methods Lung clearance index (LCI) and functional residual capacity (FRC) using multiple breath washout (MBW), plethysmographic (pleth) FRC and forced expirations from raised lung volumes were measured in 71 infants with CF (participants in the London CF Collaboration) and 54 contemporaneous healthy controls age w3 months. Results Compared with controls, and after adjustment for body size and age, LCI, FRC MBW and FRC pleth were significantly higher in infants with CF (mean difference (95% CI): 0.5 (0.1 to 0.9), p¼0.02; 0.4 (0.1 to 0.7), p¼0.02 and 0.9 (0.4 to 1.3), p<0.001, z-scores, respectively), while forced expiratory volume (FEV 0.5 ) and flows (FEF 25e75 ) were significantly lower (À0.9 (À1.3 to À0.6), p<0.001 and À0.7 (À1.1 to À0.2), p¼0.004, z-scores, respectively). 21% (15/70) of infants with CF had an elevated LCI (>1.96 z-scores) and 25% (17/68) an abnormally low FEV 0.5 (below À1.96 z-scores). While only eight infants with CF had abnormalities of LCI and FEV 0.5 , using both techniques identified abnormalities in 35% (24/68). Hyperinflation (FRC pleth >1.96 z-scores) was identified in 18% (10/56) of infants with CF and was significantly correlated with diminished FEF 25e75 (r¼À0.43, p<0.001) but not with LCI or FEV 0.5 . Conclusion Despite early diagnosis of CF by NBS and protocol-driven treatment in specialist centres, abnormal lung function, with increased ventilation inhomogeneity and hyperinflation and diminished airway function, is evident in many infants with CF diagnosed through NBS by 3 months of age.

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Section: Methodsmentioning

confidence: 99%

Lung function is abnormal in 3-month-old infants with cystic fibrosis diagnosed by newborn screening

Hoo

Thia²,

Bush

et al. 2012

Thorax

139

141

View full text Add to dashboard Cite

show abstract

“…Measurements of tidal breathing, passive respiratory mechanics and FRC p were undertaken according to international guidelines. [1][2][3][24][25][26] Not all tests were attempted on every occasion in each infant, depending on the precise research protocol. The withinsubject within-occasion coefficient of variability (CV) was calculated as [SD/mean] Â 100.…”

Section: Equipment and Measurement Protocolsmentioning

confidence: 99%

“…2,25 A minimum of 5-8 regular tidal breaths were recorded to establish a stable end-expiratory level (EEL) before activating the balloon shutter to achieve a brief airway occlusion at end-inspiration, during which elastic recoil pressure could be measured. Between 5 and 10 occlusions were performed and the mean of 3-5 valid measurements of C rs and R rs reported.…”

Section: Passive Respiratory Mechanicsmentioning

confidence: 99%

“…Between 5 and 10 occlusions were performed and the mean of 3-5 valid measurements of C rs and R rs reported. 2,25 Plethysmographic Functional Residual Capacity (FRC p ) FRC p was measured as described previously. 1,26,27 Up to five technically satisfactory measurements were obtained and the mean of 3-5 valid measurements reported.…”

Section: Passive Respiratory Mechanicsmentioning

confidence: 99%

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New reference equations to improve interpretation of infant lung function

Nguyen¹,

Hoo²,

Lum³

et al. 2012

Pediatric Pulmonology

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Summary. Rationale: With increasing use of infant pulmonary function tests (IPFTs) in both clinical and research studies, appropriate interpretation of results is essential. Objectives: To investigate the potential bias associated with ''normalising'' IPF by expressing results as a ratio of body size and to develop reference ranges for tidal breathing parameters, passive respiratory mechanics (compliance [C rs ] and resistance [R rs ]) and plethysmographic functional residual capacity (FRC p ) for white infants during the first 2 years of life. Methods: IPFTs were measured using the Jaeger BabyBody system and standardized protocols. Reference equations, adjusted for body size, age, and sex where appropriate, were created using multilevel modeling. Results: The ratio of lung function to body length changes markedly with growth, thereby precluding its use for any outcome. While the ratio of tidal volume and C rs to body weight remained relatively constant with growth, this was not the case for FRC p . Even in healthy infants, a strong inverse relationship was observed between lung function/body weight and weight z-score which could distort interpretation of results in growth-restricted infants with lung disease, such as cystic fibrosis. Reference equations were derived from 153 healthy white infants on 232 test occasions (median age 35.5 weeks [range: 2.6-104.7]). Crown-heel length was the strongest predictor of IPF. Conclusions: When reporting IPF, use of size-corrected ratios should be discouraged, with interpretation instead based on appropriate reference equations. The current equations are applicable to white infants and young children up to 2 years of age, studied using the same commercially available equipment. The extent to which these equations are applicable to infants and young children of other ethnic backgrounds or who are tested with different equipment needs to be established.

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“…Pressure and flow data were obtained and airway impedance was calculated at each frequency. Airway resistance (R aw ), tissue damping (G), and tissue elastance (H) parameters were obtained, as described elsewhere …”

Section: Methodsmentioning

confidence: 99%

Evaluation of the neuromuscular junction in a middle‐aged mouse model of congenital myasthenic syndrome

et al. 2019

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Introduction Reduced expression of the vesicular acetylcholine transporter (VAChT) leads to changes in the distribution and shape of synaptic vesicles (SVs) at neuromuscular junctions (NMJs), suggesting vesicular acetylcholine (ACh) as a key component of synaptic structure and function. It is poorly understood how long‐term changes in cholinergic transmission contribute to age‐ and disease‐related degeneration in the motor system. Methods In this study we performed confocal imaging, electrophysiology, electron microscopy, and analyses of respiratory mechanics of the diaphragm NMJ components in 12‐month‐old wild‐type (WT) and VAChTKDHOM mice. Results Diaphragms of NMJs of the VAChTKDHOM mice were similar to those in WT mice in number, colocalization, and fragmentation of pre−/postsynaptic components. However, they had increased spontaneous SV exocytosis, miniature endplate potential frequency, and diminished MEPP amplitude. No impairment in respiratory mechanics at rest was observed, probably due to the large neurotransmission safety factor of the diaphragm. Discussion The present findings help us to understand the consequences of reduced ACh release at the NMJs during aging.

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Assessment of passive respiratory mechanics in infants: doubleversussingle occlusion?

Cited by 14 publications

References 19 publications

Lung function is abnormal in 3-month-old infants with cystic fibrosis diagnosed by newborn screening

Lung function is abnormal in 3-month-old infants with cystic fibrosis diagnosed by newborn screening

New reference equations to improve interpretation of infant lung function

Evaluation of the neuromuscular junction in a middle‐aged mouse model of congenital myasthenic syndrome

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