Ventilator-induced diaphragmatic dysfunction in extremely preterm infants: a pilot ultrasound study.

To investigate the development of diaphragmatic dysfunction in ventilated extremely preterm infants (EPI) using diaphragm ultrasound (DU). EPI of less than 28 weeks' gestational age who required mechanical ventilation within six hours of birth were included in this prospective, observational study. DU was performed once a day until four days of life. End-inspiratory and end-expiratory thicknesses of the diaphragm were measured, and the diaphragm thickening fraction was calculated. A total of 20 EPI were enrolled. After intubation, there was a progressive reduction in end-inspiratory thickness of the diaphragm from baseline to day 1 (P < 0.001), but not from day 1 to day 2 (P = 0.092), day 2 to day 3 (P = 1.0), or day 3 to day 4 (P = 1.0). There was also a significant reduction in the diaphragm thickening fraction from baseline to day 1 (P < 0.001), but not from day 1 to day 2 (P = 1.0), day 2 to day 3 (P = 1.0), or day 3 to day 4 (P = 1.0).    Conclusions: This study provides the first evidence of diaphragmatic dysfunction in ventilated EPI. We demonstrated a rapid progression of ventilator-induced diaphragmatic dysfunction, with a significant reduction in diaphragm thickness and thickening fraction within 24 h of ventilation. What is Known: • Over-assistance of the ventilator suppresses respiratory effort and induces diaphragm unloading, resulting in diaphragm atrophy or dysfunction. • Diaphragmatic dysfunction contributes to prolonged ventilator dependence and poor clinical outcomes. What is New: • Most extremely preterm infants develop diaphragmatic dysfunction after intubation within 24 hours. • Diaphragm thickness and contraction ability measured by ultrasound would be important indicators of worsening breathing or respiratory outcomes.

Diagnosis and management of neonatal respiratory distress syndrome in Japan: A national survey.

BACKGROUND: Respiratory distress syndrome (RDS) is characterized by a lack of lung surfactant; therefore, biochemical evidence of surfactant deficiency is needed to diagnose RDS. European guidelines recommend surfactant administration when patients need fraction of inspired oxygen exceeding 0.3 on continuous positive airway pressure or intubation. We hypothesized that the European guidelines for surfactant administration were not adopted in Japan because of the lack of RDS diagnosis. This study aimed to investigate neonatologists' attitudes and practices regarding the diagnosis and management of RDS in Japan. METHODS: A mail-based survey regarding the diagnosis and management of RDS was conducted at 111 level III or ΙV neonatal intensive care units in Japan. The questionnaire was completed by the person in charge of each unit. RESULTS: The overall response rate for the questionnaire was 91% (101/111 centers). All respondents referred to chest radiography, and the majority (83%) of respondents referred to stable microbubble rating (SMR) for establishing the diagnosis of RDS. Surfactant administration was chiefly based on clinical conditions, chest radiography, and/or SMR. Most units in Japan do not adopt the European criteria for surfactant administration. CONCLUSION: In Japan, chest radiography and/or SMR are commonly used for the diagnosis of RDS and as the rationale for surfactant administration. Further studies from other countries are required to establish the ideal criteria for surfactant administration.

Gravity-induced loss of aeration and atelectasis development in the preterm lung: a serial sonographic assessment.

OBJECTIVE: To assess the impact of gravity and time on the changes in the distribution patterns of loss of aeration and atelectasis development in very preterm infants. STUDY DESIGN: Preterm infants less than 32 weeks gestation were included in this prospective, observational study. Infants were assessed via serial lung ultrasound (LUS) score in four lung zones, performed on days 7, 14, 21, and 28 after birth. RESULT: Eighty-eight patients were enrolled. There was a significant main effect of gravity (P < 0.001) and time (P = 0.01) on the LUS score between gravity-dependent lungs and non-dependent lungs. Moreover, there was a significant main effect of gravity (P = 0.003) on atelectasis development between the lungs. CONCLUSION: Gravity and time have an impact on the changes in the distribution patterns of gravity-induced lung injuries in preterm infants.

Ideal endotracheal tube insertion depth in neonates with a birthweight less than 750 g.

BACKGROUND: Appropriate management of the endotracheal tube (ETT) insertion depth is important. The depth calculated using Tochen's formula is overestimated in extremely-low- birthweight infants, particularly those with a birthweight <750 g. Gestational age has been shown to be particularly useful in the Neonatal Resuscitation Program, 7th edition.5 However, a randomized trial for estimating the ETT insertion depth failed to show the advantage of using gestational age over birthweight.6 Therefore, we aimed to estimate the appropriate ETT insertion depth in neonates weighing <750 g. METHODS: This was a single-center, retrospective observational study including neonates weighing <750 g who required intubation. The appropriate depth was determined by adjusting the distance between the actual ETT position and the area from the first to the second thoracic vertebra on the radiograph. Correlations between gestational age and physique were investigated using Pearson's correlation coefficient. We examined small-for- gestational-age (SGA) infants and non-SGA infants separately. RESULTS: Forty neonates were enrolled in this study. The mean gestational age and birthweight were 26.3 weeks and 620 g respectively. Twenty infants were SGA. The ETT position was deep in 35 of 40 cases, with the strongest correlation between weight and ETT insertion depth. The correlation with gestational age was not observed in this study. CONCLUSIONS: Our study showed that the ideal ETT insertion depth at birth correlates with birthweight in neonates weighing <750 g. Therefore, determination by gestational age may not be feasible in populations with a high proportion of SGA infants.

Ultrasonographic confirmation of endotracheal intubation in extremely low birthweigh infants - secondary publication.

BACKGROUND: The purpose of this study was to investigate the usefulness of ultrasonography (US) for confirmation of endotracheal tube (ETT) placement during resuscitation in extremely low birthweight (ELBW) infants. METHODS: We conducted a retrospective review of the medical records of ELBW infants in whom ETT position was verified using US between June 2016 and September 2017. We investigated the backgrounds of the patients and US investigators, and the time required for the detection of exhaled carbon dioxide using the colorimetric method and US. RESULTS: Eleven ELBW infants were evaluated using US by four neonatologists. The median duration required to determine the ETT position by the colorimetric method and US were 11 s and 3 s, respectively. In six ELBW infants, we were able to verify the ETT position more rapidly using US than using the colorimetric method, and were able to perform prompt resuscitation. Unnecessary reintubations were avoided in three ELBW infants. CONCLUSION: Ultrasonography allowed the swift confirmation of the tracheal intubations. The colorimetric method yielded false negative results; in such cases, unnecessary reintubation could have been avoided if US was used. We assessed the mechanism of false negative results and performed appropriate resuscitation.