Influence of maturation on infant diaphragm function assessed by magnetic stimulation of phrenic nerves

Dimitriou, Gabriel; Greenough, Anne; Moxham, John; Rafferty, Gerrard F.

doi:10.1002/ppul.10209

Cited by 24 publications

(15 citation statements)

References 19 publications

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“…In this study, we examined infants with a much narrower age range and matched the subjects and controls by gestational age. Gestational rather than postconceptional age was used in the matching, as the former correlates better with diaphragmatic force responses elicited by magnetic stimulation of the phrenic nerves (18). A possible explanation for our findings is that cPdi and Pimax, unlike TwPdi, do not reflect diaphragmatic performance alone.…”

Section: Discussionmentioning

confidence: 54%

Diaphragmatic Function in Infants with Surgically Corrected Anomalies

et al. 2003

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Infants with surgically correctable anomalies, abdominal wall defects (AWD) or congenital diaphragmatic hernia (CDH) may have poor postnatal diaphragmatic function, because the low intra-abdominal pressure experienced by such patients in utero could result in impaired diaphragmatic development. Our objective was to compare postoperative diaphragmatic function of infants with CDH or AWD to that of gestational age-matched controls. Diaphragmatic function was assessed by measurement of the transdiaphragmatic pressure and maximum inspiratory pressure at the mouth generated during crying against an occlusion. In addition, the transdiaphragmatic pressure produced by unilateral and/or bilateral magnetic stimulation of the phrenic nerves (TwPdi) was examined. Lung volume was assessed by measurement of functional residual capacity (FRC) using a helium gas dilution technique. Ten infants with CDH, 26 with AWD infants (19 gastroschisis, seven exomphalos), and 36 gestational age-matched controls were studied. Compared with their matched controls, the eight CDH infants with left-sided defects had significantly lower left (p Ͻ 0.01) and right (p Ͻ 0.05) TwPdi and FRC (p Ͻ 0.01), and the gastroschisis infants, but not those with exomphalos, had significantly lower left and right TwPdi (p Ͻ 0.05). There were no significant differences in transdiaphragmatic pressure and maximum inspiratory pressure at the mouth between the CDH or AWD infants and the controls. Surgically correctable birth defects, CDH, and AWD are common and associated with respiratory morbidity. Infants with CDH can suffer bronchopulmonary dysplasia and recurrent infections (1, 2) and, in both conditions, pulmonary function abnormalities are demonstrated outside the perinatal period (1-4). These problems may be due to poor antenatal lung growth. Abnormal diaphragmatic function impairs antenatal lung growth (5-8) and we hypothesize that infants with CDH or AWD may have abnormal diaphragmatic development and function. CDH and AWD infants experience low intraabdominal pressure in utero, as viscera are extra-abdominal. Repetitive (9) or passive (10) stretch of skeletal muscles is important to increase myofiber diameter and area. The ipsilateral diaphragm of a CDH infant would be expected to function poorly immediately after operative repair but, if our hypothesis is correct, then the contralateral diaphragm function would also be reduced because of the low intra-abdominal pressure in utero. Diaphragmatic function in neonates has previously been assessed by measurement of cPdi (11)

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Section: Discussionmentioning

confidence: 54%

Diaphragmatic Function in Infants with Surgically Corrected Anomalies

et al. 2003

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“…Unlike CMS, BAMPS and UMS were supramaximal, with a mean bilateral Pdi,tw, right Pdi and left Pdi of 8.7, 4.1 and 4.5 cmH 2 O, respectively. Pdi,tw correlated with gestational age at birth and postconceptional age [126]. Using similar techniques, the same group have demonstrated that diaphragm function is impaired in postoperative infants with congenital diaphragmatic hernia and gastroschisis [127], and that Pdi,tw elicited by UMS is sensitive enough to diagnose neonatal diaphragm paralysis [128].…”

Section: Childrenmentioning

confidence: 71%

Magnetic stimulation for the measurement of respiratory and skeletal muscle function

Man¹

2004

Eur Respir J

117

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Respiratory and skeletal muscle function is of interest in many areas of pulmonary and critical care medicine. The capacity of the respiratory muscle pump to respond to the load imposed by disease is the basis of an understanding of ventilatory failure. Over the last four decades, considerable progress has been made in quantifying the capacity of the respiratory muscles, in terms of strength, endurance and fatigue. With the development of magnetic stimulation, it has recently become possible to nonvolitionally assess the respiratory muscles in a clinically acceptable way. This is of particular interest in the investigation of patients receiving critical care, those with neuromuscular disease, and in children where volitional efforts are either not possible or likely to be sub-maximal. Furthermore, the adaptation of these techniques to quantify the strength of peripheral muscles, such as the quadriceps, has allowed the effects of muscle training or rehabilitation, uninfluenced by learning effect, to be assessed. This article focuses on the physiological basis of magnetic nerve stimulation, and reviews how the technique has been applied to measure muscle strength and fatigue, with particular emphasis upon the diaphragm. The translation of magnetic stimulation into a clinical tool is described, and how it may be of diagnostic, prognostic and therapeutic value in several areas of pulmonary medicine. In particular, the use of magnetic stimulation in neuromuscular disease, the intensive care setting, chronic obstructive pulmonary disease and paediatrics will be discussed. The nonvolitional assessment of skeletal musclesFor routine muscle strength measurements, the force generated from a maximum voluntary contraction (MVC) is often used. However volitional, effort-dependent manoeuvres for measuring strength are not always suitable for patients as the ability to perform a true MVC relies upon subject motivation and cooperation. This is particularly so in patients on intensive care units (ICU), children, patients with cognitive difficulties, and those patients prevented from performing a true MVC by pain (for example, following surgery). However, even in well-motivated subjects, sub-maximal muscle activation is common in routine clinical practice [1]. As volitional manoeuvres are influenced by a learning effect, the value of MVC is also limited in studies of training or rehabilitation. Consequently, there has been a need for nonvolitional methods to assess muscle strength. Skeletal muscle physiologySkeletal muscle is controlled by electrical impulses conducted by motor neurones that lead to the release of acetylcholine from the motor end plate, thus depolarising the muscle cell membrane. The force generated by muscle contraction is dependent upon a number of factors, including the number of muscle fibres stimulated, muscle length at the time of stimulation and the frequency of stimulation. The force-frequency curve of a muscle is of particular relevance in the understanding of nonvolitional techniques to asse...

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“…Maximum airway (aPiMax) or esophageal (ePiMax) pressure measurements during airway occlusion are regarded as gold standard measures of respiratory muscle strength in adults (38). If maximal voluntary efforts cannot be guaranteed (14, 38–42), twitch stimulation of the phrenic nerve is sometimes substituted (38, 43), although this technique may have high variability and limited reproducibility in children (44–49). In addition, diaphragm strength can be isolated from the intercostal muscles by using two simultaneous pressure transducers (to calculate trans-diaphragmatic pressure) (38, 50), although this is not practical for repeated use in children and no double-balloon catheters are commercially available for infants.…”

Section: Discussionmentioning

confidence: 99%

Risk Factors for Pediatric Extubation Failure: The Importance of Respiratory Muscle Strength*

Khemani

Sekayan²,

Hotz³

et al. 2017

Critical Care Medicine

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Objective Respiratory muscle weakness frequently develops during mechanical ventilation, although in children there are limited data about its prevalence and whether it is associated with extubation outcomes. We sought to identify risk factors for pediatric extubation failure, with specific attention to respiratory muscle strength. Design Secondary analysis of prospectively collected data Setting Tertiary care pediatric ICU Patients 409 mechanically ventilated children Interventions Respiratory measurements using esophageal manometry and respiratory inductance plethysmography were made pre-extubation during airway occlusion and on CPAP of 5 and PS of 10/ above PEEP 5 cmH20, as well as 5 and 60 minutes post-extubation. Measurements and Main Results Thirty-four patients (8.3%) were re-intubated within 48 hours of extubation. Re-intubation risk factors included lower maximum airway pressure during airway occlusion (aPiMax), longer length of ventilation, post-extubation upper airway obstruction (UAO), high respiratory effort post-extubation (Pressure Rate Product (PRP), Pressure Time Product, Tension Time Index) and high post-extubation Phase Angle. Nearly 35% of children had diminished respiratory muscle strength (aPiMax ≤ 30 cmH20) at the time of extubation, and were nearly three times more likely to be re-intubated than those with preserved strength (aPiMax >30 cmH20; 14% vs. 5.5%, p=0.006). Re-intubation rates exceeded 20% when children with low aPiMax had moderately elevated effort after extubation (PRP > 500), while children with preserved aPiMax had re-intubation rates > 20% only when post-extubation effort was very high (PRP > 1000). When children developed post-extubation UAO, re-intubation rates were 47.4% for those with low aPiMax compared to 15.4% for those with preserved aPiMax (p=0.02). Multivariable risk factors for re-intubation included acute neurologic disease, lower aPiMax, post-extubation UAO, higher pre-extubation PEEP, higher post-extubation PRP, and lower height. Conclusions Neuromuscular weakness at the time of extubation was common in children and was independently associated with re-intubation, particularly when post-extubation effort was high.

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Influence of maturation on infant diaphragm function assessed by magnetic stimulation of phrenic nerves

Cited by 24 publications

References 19 publications

Diaphragmatic Function in Infants with Surgically Corrected Anomalies

Diaphragmatic Function in Infants with Surgically Corrected Anomalies

Magnetic stimulation for the measurement of respiratory and skeletal muscle function

Risk Factors for Pediatric Extubation Failure: The Importance of Respiratory Muscle Strength*

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