Time constant of inspiratory muscle relaxation in cystic fibrosis

Dassios, Theodore; Kaditis, Athanasios G.; Katelari, A.; Chrousos, George P.; Doudounakis, Stavros; Dimitriou, Gabriel

doi:10.1038/pr.2015.2

Cited by 14 publications

(8 citation statements)

References 27 publications

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“…The rate of relaxation can be quantified by the time constant of respiratory muscle relaxation ( τ ), which is calculated as the reciprocal of the absolute value of the slope of the decline in pressure as a function of time at the lower 60% part of the curve. Higher values of τ indicate slower relaxation and increased risk of respiratory muscle fatigue, while lower values of τ indicate rapid relaxation and healthy muscle function [15]. τ has not been studied in prematurely born infants undergoing MV.…”

Section: Introductionmentioning

confidence: 99%

Relaxation Rate of the Respiratory Muscles and Prediction of Extubation Outcome in Prematurely Born Infants

2017

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Background: Accurate prediction of extubation outcome could result in a significant reduction of respiratory morbidity in premature neonates. Objectives: To assess whether the respiratory muscle time constant of relaxation (τ) predicted extubation outcome in mechanically ventilated, premature infants. Methods: Forty-six mechanically ventilated infants with a median gestational age of 26 (interquartile range [IQR] 25-29) weeks were prospectively studied. τ was calculated from the reciprocal of the slope of the decline in airway pressure as a function of time. Measurements of τ were done during 5-10 min of a spontaneous breathing test (SBT) prior to extubation. During the first and last minute of the SBT, τ₁ and τ₂, respectively, were assessed, and the difference between them was calculated (Δτ). Results: The median τ₂ was significantly higher in infants whose extubation failed (20.7 [IQR 12.9-34.7] s/cm H₂O) than in infants whose extubation succeeded (8.2 [IQR 6.2-17.8] s/cm H₂O, p = 0.002). The median Δτ was significantly higher in infants whose extubation failed (10.3 [IQR 4.4-23.9] s/cm H₂O) than in infants whose extubation succeeded (-1.63 [IQR -5.7 to 0.3] s/cm H₂O, p = 0.001). Extubation failure was associated with τ₂ (p = 0.011) and Δτ (p = 0.010) after correcting for postmenstrual age, patent ductus arteriosus, and intraventricular haemorrhage. Receiver operator characteristic curve analysis demonstrated that Δτ predicted extubation failure with an area under the curve of 0.937. A Δτ of +1.02 s/cm H₂O predicted extubation failure with 94% sensitivity and 83% specificity. Conclusions: The respiratory muscle time constant of relaxation during an SBT was significantly greater in infants whose extubation failed and could be used to predict extubation outcome in prematurely born infants.

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Section: Introductionmentioning

confidence: 99%

Relaxation Rate of the Respiratory Muscles and Prediction of Extubation Outcome in Prematurely Born Infants

2017

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“…To our knowledge, apart from various studies about the relaxation rate in healthy adults (21,23,33) and different diseases [COPD (51), cystic fibrosis (55,56), and intubated patients weaning from mechanical ventilation (31)], the literature is scarce about the measurements of MRPD, τ, CT, and 1/2RT in neuromuscular disease patients precluding the possibility of comparing our data to data derived from a similar population. Our results showed a decreased MRPD in middle stage ALS when compared to healthy subjects and, as it is derived from the initial incline of the SNIP curve and reflects respiratory muscle function (11) as well as respiratory motor output (19), we believe that this parameter is linked to the decreased capacity of the diaphragm to generate force and expand the lungs (39).…”

Section: Discussionmentioning

confidence: 99%

Multiparametric analysis of sniff nasal inspiratory pressure test in middle stage amyotrophic lateral sclerosis

Sarmento¹,

Aliverti²,

Marques³

et al. 2018

Clinical Respiratory Physiology, Exercise and Functional Imaging

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“…1). 16 Higher values of signify a slower relaxation and impaired respiratory muscle function, whereas lower values of signify a faster relaxation and more efficient respiratory muscle function. 15 The part of the airway pressure trace with smooth decay was hand selected and analyzed.…”

Section: Calculation Of the Ventilation Efficiency Index And The Respmentioning

confidence: 99%

Ventilation Efficiency and Respiratory Muscle Function at Different Levels of CPAP in Intubated Prematurely Born Infants

Dassios

Dixon²,

Greenough

2018

Respir Care

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BACKGROUND: CPAP improves respiratory function in prematurely born infants by establishing and maintaining functional residual capacity, but the level of CPAP that optimizes respiratory function has not been adequately described. We compared ventilation efficiency and respiratory muscle function at different levels of CPAP. METHODS: We studied spontaneously breathing, intubated convalescent premature infants at King's College Hospital NHS Foundation Trust and calculated the ventilation efficiency index and the respiratory muscle time constant of relaxation () at the end of 3 consecutive 5-min periods at 4, 6, and 8 cm H 2 O of CPAP delivered in random order. RESULTS: Between February 2016 and August 2016, 38 infants with a median gestational age of 27 (interquartile range [IQR], 25؊30) weeks and a median birthweight of 0.88 (IQR, 0.73-1.02) kg were studied. At a CPAP level of 6 cm H 2 O, the median ventilation efficiency index was higher (1.52 [IQR, 1.02-2.27]) and median was lower (15.6 [IQR, 10.1-21.3]) s/cm H 2 O] compared with the median ventilation efficiency index (0.75 [IQR, 0.56-1.03]) and median (23.3 [IQR, 15.4-35.2] sec/cm H 2 O) at CPAP of 4 cm H 2 O (P < .001 for both). At a CPAP level of 8 cm H 2 O, median ventilation efficiency index was significantly lower (1.27 [IQR, 1.04-1.91]) and median was not significantly different (11.2 [IQR, 8.3-18.9] s/cm H 2 O) compared with ventilation efficiency index and at CPAP of 6 cm H 2 O (P < .001 and P ‫؍‬ .12, respectively). After multiple logistic regression, the level of CPAP was independently associated with the ventilation efficiency index (adjusted P < .001) and (adjusted P ‫؍‬ .003). CONCLUSIONS: Increasing the level of CPAP from 4 to 6 cm H 2 O was associated with enhanced ventilation efficiency and respiratory muscle function in convalescent premature infants on ventilation, but there was no further benefit from increasing the pressure >6 cm H 2 O.

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Time constant of inspiratory muscle relaxation in cystic fibrosis

Abstract: Articles Dassios et al.status (CF vs. non-CF) had a significant effect on τ (P < 0.001; Figure 1), but age group and the interaction of age group with health status did not have significant effects (P = 0.10 and P = 0.71, respectively).

Cited by 14 publications

References 27 publications

Relaxation Rate of the Respiratory Muscles and Prediction of Extubation Outcome in Prematurely Born Infants

Relaxation Rate of the Respiratory Muscles and Prediction of Extubation Outcome in Prematurely Born Infants

Multiparametric analysis of sniff nasal inspiratory pressure test in middle stage amyotrophic lateral sclerosis

Ventilation Efficiency and Respiratory Muscle Function at Different Levels of CPAP in Intubated Prematurely Born Infants

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