Influence of jacket placement on respiratory compliance during raised lung volume measurements in infants

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

doi:10.1002/1099-0496(200101)31:1<51::aid-ppul1007>3.0.co;2-7

Cited by 10 publications

(1 citation statement)

References 17 publications

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“…If a rebreathing bag is being used measurements of lung volume should precede those of airway resistance, unless care is taken to minimize the period of rebreathing. The baseline measures of FRCp should also be made with minimal dead space and with no additional equipment such as "squeeze" jackets in situ [15]. Posture measurements should be performed in the supine position with the head in the midline and the neck slightly extended.…”

Section: Measurement Conditionsmentioning

confidence: 99%

Plethysmographic measurements of lung volume and airway resistance

et al. 2001

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Functional residual capacity (FRC) is the only static lung volume that can be measured routinely in infants. It is important for interpreting volume-dependent pulmonary mechanics such as airway resistance or forced expiratory flows, and for defining normal lung growth. Despite requiring complex equipment, the plethysmographic method for measuring FRC is very simple to apply and, unlike the gas dilution techniques, enables repeat measures of lung volume to be obtained within a few minutes. This method has the further advantage that with suitable adaptations to the equipment, simultaneous measurements of airway resistance can also be obtained.The aim of this paper is to provide recommendations pertaining to equipment requirements, study procedures and reporting of data for plethysmographic measurements in infants. Implementation of these recommendations should help to ensure that such measurements are as accurate as possible and that meaningful comparisons can be made between data collected in different centres or with different equipment. These guidelines cover numerous aspects including terminology and definitions, equipment, data acquisition and analysis and reporting of results and also highlight areas where further research is needed before consensus can be reached.

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Section: Measurement Conditionsmentioning

confidence: 99%

Plethysmographic measurements of lung volume and airway resistance

et al. 2001

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Exploring the relationship between forced maximal flow at functional residual capacity and parameters of forced expiration from raised lung volume in healthy infants

Ranganathan¹,

Hoo²,

Lum³

et al. 2002

Pediatric Pulmonology

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The raised volume rapid thoraco-abdominal compression technique (RVRTC) is being increasingly used to assess airway function in infants, but as yet no consensus exists regarding the equipment, methods, or analysis of recorded data. The aim of this study was to explore the relationship between maximal flow at functional residual capacity (V'(maxFRC)) and parameters derived from raised lung volumes, and to address analytical aspects of the latter technique in an attempt to assist with future standardization initiatives. Forced vital capacity (FVC) from lung volume raised to 3 kPa, timed forced expiratory volumes (FEV(t)), and forced expiratory flow parameters at different percentages of expired FVC (FEF(%)) were measured in 98 healthy infants (1-69 weeks of age). V'(maxFRC) using the tidal rapid thoraco-abdominal compression (RTC) technique was also measured. The within-subject relationships and within-subject variability of the various parameters were assessed. Duration of forced expiration was < 0.5 sec in 5 infants, meaning that FEV(0.3) and FEV(0.4) were the only timed volume parameters that could be calculated in all infants during the first months of life, and even when it could be calculated, FEV(0.5) approached FVC in many of these infants. It is recommended that FEV(0.4) be routinely reported in infants less than 3 months of age. Contrary to previous reports, within subject variability of V'(maxFRC) was less than that of FEF(75) (mean CV = 6.3% and 8.9%, respectively).A more standardized protocol when analyzing data from the RVRTC would facilitate comparisons of results between centers in the future.

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Influence of jacket tightness and pressure on raised lung volume forced expiratory maneuvers in infants

Lum

Hoo

Stocks

2002

Pediatric Pulmonology

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While the use of the raised volume rapid thoraco-abdominal compression (RVRTC) technique has been shown to provide new insights into airway and pulmonary pathophysiology in infants, and appears to resemble the spirometric techniques used in older subjects, there is as yet no consensus regarding measurement procedures, which are known to vary considerably between laboratories (Gappa [1999] Pediatr Pulmonol 28:391-393). The aims of this study were to assess the effects of tightness of jacket fit, the efficiency with which pressure is transmitted from the jacket to the intrathoracic airways, and the effect of jacket pressure on parameters derived from the RVRTC technique. Paired forced expiratory maneuvers were performed in 20 infants with the jacket snugly or loosely wrapped around the infant's torso, and in a further 21 infants using "optimal" or a higher jacket pressure (P(j)) (1-2 kPa above "optimal" P(j)). When either a loosened jacket or a higher than "optimal" P(j) was used, forced expired flow at low lung volumes (FEF(75)) was significantly reduced by, on average, 8% and 7%, respectively. There were, however, minimal changes in forced vital capacity (FVC) or forced expired volume in 0.4 sec (FEV(0.4)). The observed changes may have been due to the increased pressure transmitted to the intrathoracic structures under these experimental conditions, and emphasize the need to assess optimal jacket pressure within each infant when using the RVRTC technique. In addition, when using a loosened jacket or a higher than "optimal" P(j), chest wall and upper airway reflexes such as glottic closure, peripheral airway closure, and negative flow dependence were more evident.

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Influence of jacket placement on respiratory compliance during raised lung volume measurements in infants

Cited by 10 publications

References 17 publications

Plethysmographic measurements of lung volume and airway resistance

Plethysmographic measurements of lung volume and airway resistance

Exploring the relationship between forced maximal flow at functional residual capacity and parameters of forced expiration from raised lung volume in healthy infants

Influence of jacket tightness and pressure on raised lung volume forced expiratory maneuvers in infants

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