Diaphragmatic Thickness and Excursion in Preterm Infants With Bronchopulmonary Dysplasia Compared With Term or Near Term Infants: A Prospective Observational Study

Sex-Based Differences in the Sonographic Characterization of Diaphragm Thickness in Preterm Infants With Bronchopulmonary Dysplasia at Term Corrected Age: A Secondary Analysis of a Prospective Study

OBJECTIVE

To determine the sex-specific diaphragm thickness in infants with bronchopulmonary dysplasia (BPD) as well as in healthy term and near-term infants.

METHODS

We performed a secondary analysis of an observational study to compare the sonographic diaphragm thickness at end expiration (DTexp) in female and male infants. The study included infants with BPD and healthy near-term and term infants. To account for differences in anthropometric measurements, we calculated the DTexp as a ratio of body surface area (BSA). Statistical analysis was performed using R statistical software.

RESULTS

Of the 111 infants included, 54 (48.6%) were female. There were no significant differences in mean (SD) birth gestation [26.2 (2.1) vs 26.3 (2.1) weeks] and mean study age [38.0 (2.0) vs 37.4 (1.1) weeks] of male vs female infants with BPD. The mean (SD) DTexp [1.5 (0.4) mm vs 1.2 (0.3) mm, P = .02] and DTexp/BSA [8.3 (2.3) mm/m2 vs 6.7 (1.6) mm/m2, P < .01] were significantly thicker in female than male infants with BPD. In contrast, there were no significant differences in DTexp between sexes [1.5 (0.4) mm vs 1.5 (0.3) mm, P = .89] within the healthy control group. Moreover, there were no differences in inspiratory diaphragm thickness, diaphragm thickness fraction, or excursion between males and females in the BPD or healthy groups.

CONCLUSIONS

Male infants with BPD exhibit thinner diaphragm thickness compared with female infants. Its implication on higher rates of BPD in preterm males is unclear, but this finding highlights the need for further investigation.

Ultrasound evaluation of diaphragm kinetics after minimally invasive surfactant administration

PURPOSE

Concerns remain on different alveolar deposition of surfactant between LISA and INSURE methods. Ultrasound evaluation of diaphragm kinetics may provide clinical evidence on this issue, as indirect representation of the respiratory system compliance.

METHODS

This was a prospective-observational pilot study. The inclusion criterion was CPAP-supported infants ≤ 32 weeks with RDS receiving surfactant via minimally invasive technique. 52 patients randomized for surfactant administration via LISA or INSURE methods were enrolled. Right diaphragm (RD) global mean peak velocity (MPV) by Pulsed-Wave Tissue Doppler Imaging (PTDI) was recorded before and two hours after surfactant administration with simultaneous measurements of oxygen saturation (SpO2)/fraction of inspired oxygen (FiO2) (SF ratio). Mechanical ventilation ≤ 72 h from birth represented treatment failure.

RESULTS

LISA infants had significantly higher gestational age (p = 0.029) and birth weight (p = 0.030) with lower CRIB-II scores (p = 0.030) than INSURE infants. LISA infants showed higher median MPV at baseline RD-PTDI US assessment (p = 0.024), but post-surfactant median MPV and other the investigated variables were similar at the adjusted analysis for gestational age and sedation. 8/52 (15%) infants who failed treatment had a significantly lower SF ratio (p = 0.002) and higher median MPV at RD-PTDI US (p = 0.004) after surfactant administration, despite the higher CPAP support level before (p = 0.007) and after (p = 0.001) surfactant administration. A full course of antenatal steroids was protective against mechanical ventilation (p = 0.038).

CONCLUSIONS

Different minimally invasive surfactant administration techniques do not appear to influence diaphragm kinetics evaluated by RD-PTDI US.

Sonographic assessment of diaphragmatic thickness and excursion to predict CPAP failure in neonates below 34 weeks of gestation: A prospective cohort study

BACKGROUND

To evaluate the diagnostic accuracy of sonographic assessment of diaphragmatic dimensions and excursions in predicting Continuous Positive Airway Pressure (CPAP) failure in preterm neonates with respiratory distress.

METHODS

Prospective cohort study among preterm neonates less than 34 weeks of gestation who were hemodynamically stable and either admitted with respiratory distress or who developed respiratory distress shortly after admission to the NICU and having Silverman-Anderson Score (SAS) ≥ 3/10 were included. We performed sonographic assessment of diaphragmatic dimensions and excursions before and one hour ±30 minutes after application of CPAP. 'CPAP failure' was defined as combined outcome of the need of surfactant and/or upgradation of respiratory support within first 72 hours after a trial of CPAP. Clinical parameters and diaphragmatic measurements were compared between CPAP failure and success groups.

RESULTS

Of 62 participants, 20 (32%) failed CPAP. On binomial logistic regression (after adjustment for gestational age and birth weight), initial SAS, higher diaphragmatic excursion (both left and right, before and after CPAP application), lower left hemidiaphragm diaphragmatic thickness fraction (DTF) (before CPAP application) and lower right DTF (after CPAP application) were independent predictors of CPAP failure. However, the receiver-operating characteristics curves showed that excursions of right and left hemi-diaphragm both before and after CPAP application, had highest accuracies in predicting CPAP failure (AUC 0.84, 0.80 and 0.86, 0.78, respectively; p < .001).

CONCLUSION

Diaphragmatic excursion can be a useful parameter to predict the failure of CPAP in preterm neonates with respiratory distress.

The increase in diaphragm thickness in preterm infants is related to birth weight: a pilot study

Diaphragm ultrasound (DU) has been used in adult and pediatric critical patients in relation to prediction of extubation success or to detect diaphragm dysfunction, but there is a lack of evidence in neonates. Our aim is to study the evolution of diaphragm thickness in preterm infants, as well as related variables. This prospective monocentric observational study included preterm infants born before 32 weeks (PT32). We performed DU to measure right and left inspiratory and expiratory thickness (RIT, LIT, RET, and LET) and calculated the diaphragm-thickening fraction (DTF) in the first 24 h of life and then weekly until 36 weeks postmenstrual age, death, or discharge. Using multilevel mixed-effect regression, we evaluated the influence of time since birth on diaphragm measurements, as well as bronchopulmonary dysplasia (BPD), birth weight (BW), and days of invasive mechanical ventilation (IMV). We included 107 infants, and we performed 519 DUs. All diaphragm thickness increased with time since birth, but the only additional variable that influenced this growth was BW: beta coefficients RIT = 0.00006; RET = 0.00005; LIT = 0.00005; and LET = 0.00004, p < 0.001. Right DTF values remained stable since birth but left DTF increased with time only in infants with BPD.   Conclusion: In our population we found that the higher the BW, the higher diaphragm thicknesses at birth and follow-up. Contrary to the previously published findings in adult and pediatric settings, we were unable to describe a relationship between days of IMV and diaphragm thickness in PT32. The final diagnosis of BPD does not influence this increase either, but it does increase left DTF. What is Known: • Diaphragm thickness and diaphragm thickening fraction have been related to the time on invasive mechanical ventilation in adults and pediatric patients, as well as with extubation failure. • Very few evidence is yet available on the use of diaphragmatic ultrasound in preterm infants. What is New: • Birth weight is the only variable related to diaphragm thickness in preterm infants born before 32 weeks postmenstrual age. • Days of invasive mechanical ventilation do not influence diaphragm increase in thickness in preterm infants.

Reference values of diaphragmatic dimensions in healthy children aged 0-8 years

Diaphragmatic thickness (Tdi) and diaphragm thickening fraction (dTF) are widely used parameters in ultrasound studies of the diaphragm in mechanically ventilated children, but normal values for healthy children are scarce. We determined reference values of Tdi and dTF using ultrasound in healthy children aged 0-8 years old and assessed their reproducibility. In a prospective, observational cohort, Tdi and dTF were measured on ultrasound images across four age groups comprising at least 30 children per group: group 1 (0-6 months), group 2 (7 months-1 year), group 3 (2-4 years) and group 4 (5-8 years). Ultrasound images of 137 healthy children were included. Mean Tdi at inspiration was 2.07 (SD 0.40), 2.09 (SD 0.40), 1.69 (SD 0.30) and 1.72 (SD 0.30) mm for groups 1, 2, 3 and 4, respectively. Mean Tdi at expiration was 1.64 (SD 0.30), 1.67 (SD 0.30), 1.38 (SD 0.20) and 1.42 (SD 0.20) mm for groups 1, 2, 3 and 4, respectively. Mean Tdi at inspiration and mean Tdi at expiration for groups 1 and 2 were significantly greater than those for groups 3 and 4 (both p < 0.001). Mean dTF was 25.4% (SD 10.4), 25.2% (SD 8.3), 22.8% (SD 10.9) and 21.3% (SD 7.1) for group 1, 2, 3 and 4, respectively. The intraclass correlation coefficients (ICC) representing the level of inter-rater reliability between two examiners performing the ultrasounds was 0.996 (95% CI 0.982-0.999). ICC of the inter-rater reliability between the raters in 11 paired assessments was 0.989 (95% CI 0.973-0.995).   Conclusion: Ultrasound measurements of Tdi and dTF were highly reproducible in healthy children aged 0-8 years.    Trial registration: ClinicalTrials.gov identifier (NCT number): NCT04589910. What is Known: • Diaphragmatic thickness and diaphragm thickening fraction are widely used parameters in ultrasound studies of the diaphragm in mechanically ventilated children, but normal values for healthy children to compare these with are scarce. What is New: • We determined normal values of diaphragmatic thickness and diaphragm thickening fraction using ultrasound in 137 healthy children aged 0-8 years old. The diaphragmatic thickness of infants up to 1 year old was significantly greater than that of children from 2 to 8 years old. Diaphragmatic thickness decreased with an increase in body surface area. These normal values in healthy children can be used to assess changes in respiratory muscle thickness in mechanically ventilated children.

Ultrasonographic assessment of diaphragmatic function in preterm infants on non-invasive neurally adjusted ventilatory assist (NIV-NAVA) compared to nasal intermittent positive-pressure ventilation (NIPPV): a prospective observational study

NIV-NAVA mode for respiratory support in preterm infants is not well-studied. This study aimed to describe the diaphragmatic function, diaphragmatic excursion (DE), and thickness fraction (DTF), in preterm infants < 30 weeks' gestation supported by NIV-NAVA compared to NIPPV using bedside ultrasonography. In this consecutive prospective study, DE, diaphragmatic thickness at end of expiration (DT_exp), end of inspiration (DT_ins), and DTF were assessed using bedside ultrasound. Lung aeration evaluation using lung ultrasound score (LUS) was performed for the two groups. Diaphragmatic measurements and LUS were compared for the 2 groups (NIV-NAVA group versus NIPPV group). Statistical analyses were conducted using the SPSS software version 22. Out of 70 infants evaluated, 40 were enrolled. Twenty infants were on NIV-NAVA and 20 infants on NIPPV with a mean [SD] study age of 25.7 [0.9] weeks and 25.1 [1.4] weeks respectively (p = 0.15). Baseline characteristics and respiratory parameters at the time of the scan showed no significant difference between groups. DE was significantly higher in NIV-NAVA with a mean SD of 4.7 (1.5) mm versus 3.5 (0.9) mm in NIPPV, p = 0.007. Additionally, the mean (SD) of DTF for the NIV-NAVA group was 81.6 (30) % vs 78.2 (27) % for the NIPPV group [p = 0.71]. Both groups showed relatively high LUS but no significant difference between groups [12.8 (2.6) vs 12.6 (2.6), p = 0.8].  Conclusion: Preterm infants managed with NIV-NAVA showed significantly higher DE compared to those managed on NIPPV. This study raises the hypothesis that NIV-NAVA could potentially improve diaphragmatic function due to its synchronization with patients' own breathing. Longitudinal studies to assess diaphragmatic function over time are needed.  Trial registry: Clinicaltrials.gov (NCT05079412). Date of registration September 30, 2021. What is Known: • NIV-NAVA utilizes diaphragmatic electrical activity to provide synchronized breathing support. • Evidence for the effect of NIV-NAVA on diaphragmatic thickness fraction (DTF) and excursion (DE) is limited. What is New: • Ultrasonographic assessment of diaphragmatic function (DTF and DE) is feasible. • In preterm infants, DE was significantly higher in infants supported with NIV-NAVA compared to those supported with NIPPV.

Diaphragmatic ultrasound and patent ductus arteriosus in the newborn: A retrospective case series

Background

Patent ductus arteriosus (PDA) and diaphragmatic dysfunction are frequently seen in newborn infants but their relationship remains unknown. We aimed to use point of care ultrasound to compare diaphragmatic kinetics in infants with a PDA compared to in those without a PDA.

Methods

M-mode ultrasonography was used to measure the mean inspiratory velocity (V _I) in newborn infants with and without a haemodynamically significant PDA admitted in the Neonatal Unit at King's College Hospital during a three month period.

Results

Seventeen diaphragmatic ultrasound studies were reviewed from 14 infants with a median (IQR) gestational age of 26.1 (25.8-30.6) weeks, birth weight of 780 (660-1385) gr at a postnatal age of 18 (14-34) days. Eight scans had evidence of a PDA. The median (IQR) V_I was significantly lower in scans with a PDA [1.01 (0.78-1.86) cm/s] compared to the ones without a PDA [3.21 (2.80-3.59) cm/s, p < 0.001]. The median (IQR) gestational age was lower in infants with a PDA [25.8 (25.6-27.3) weeks] compared to infants without a PDA [29.0 (26.1-35.1) weeks, p = 0.007]. Using multivariable linear regression analysis the V_I was independently associated with a PDA (adjusted p < 0.001) but not with the gestational age (adjusted p = 0.659).

Conclusions

Patent ductus arteriosus was associated with a lower mean inspiratory velocity in neonates and this effect was independent of gestational age.

Targeted management of evolving and established chronic lung disease of prematurity assisted by cardiopulmonary ultrasound: A case report of four patients

Bronchopulmonary dysplasia (BPD) is one of the most common complications of premature birth. The current definition of BPD is based on the duration of oxygen therapy and/or respiratory support. Among the pitfalls of all the diagnostic definitions, the lack of a proper pathophysiologic classification makes it difficult to choose an appropriate drug strategy for BPD. In this case report, we describe the clinical course of four premature infants, admitted to the neonatal intensive care unit, for whom the use of lung and cardiac ultrasound was an integral part of the diagnostic and therapeutic process. We describe, for the first time to our knowledge, four different cardiopulmonary ultrasound patterns of evolving and established chronic lung disease of prematurity and the consequent therapeutic choices. This approach, if confirmed in prospective studies, may guide the personalized management of infants suffering from evolving and established BPD, optimizing the chances of success of the therapies and at the same time reducing the risk of exposure to inadequate and potentially harmful drugs.