Pathophysiology of Hyponatremia in Preterm Infants with Relative Adrenal Insufficiency after the Early Neonatal Period.

OBJECTIVE: Preterm infants often develop relative adrenal insufficiency (RAI) not only within the early neonatal period but also beyond this period. RAI is commonly accompanied by hyponatremia, but the pathogenesis of hyponatremia with RAI has not been clarified. This study aimed to investigate the pathophysiology of hyponatremia in infants with RAI. STUDY DESIGN: This is a single-centered retrospective cohort study. Preterm infants born at <30 weeks of gestation or birth weight <1,000 g were enrolled. They were divided into the RAI group and the non-RAI group. The data of serum and urine examination, the amount of sodium intake, and fractional excretion of sodium (FENa) were compared between the two groups. In the RAI group, data before and after the administration of hydrocortisone were also compared. RESULTS: Sixteen infants in the RAI group and 35 infants in the non-RAI group were included in the analysis. In the RAI group, hyponatremia was common and preceded other clinical symptoms, such as oliguria and decreased blood pressure, therefore, hyponatremia with RAI was not likely to be caused by dilution due to oliguria. There was no difference in the FENa between the two groups (adjusted for postconceptional age at examination), therefore, it is not likely that hyponatremia with RAI was mainly caused by excessive renal sodium loss. Since sodium intake was rather higher in the RAI group than in the non-RAI group, it is unlikely that insufficient sodium supplementation was the cause of RAI. Hyponatremia with RAI was considered to be likely caused by vascular hyperpermeability. CONCLUSION: Hyponatremia is a common symptom among preterm infants with RAI and its pathogenesis can be vascular hyperpermeability. KEY POINTS: · The pathogenesis of hyponatremia with RAI can be vascular hyperpermeability.. · Hyponatremia is common among preterm infants with RAI.. · Hyponatremia with RAI preceded other clinical symptoms..

Comparison of two methods measuring serum alkaline phosphatase in neonates.

BACKGROUND: Serum alkaline phosphatase (ALP) is a useful bone turnover marker to diagnose metabolic bone disease in preterm infants. In Japan, serum ALP levels were generally measured using the Japan Society of Clinical Chemistry (JSCC) method. It is problematic that ALP levels measured using the JSCC method tend to be higher in people with blood types B and O regardless of the disease. For international standardization, since 2020, the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) method has been used as a reference method for ALP measurement instead of the JSCC method. However, no report has investigated the correlation between these two methods in neonates. We therefore aimed to compare the JSCC and IFCC methods and demonstrate a conversion formula in neonates. METHODS: In this retrospective study, we used a total of 402 samples in 49 preterm and 38 term infants. Serum ALP levels were measured using the JSCC and IFCC methods. RESULTS: Alkaline phosphatase measured using the JSCC method strongly correlated with that measured using the IFCC method in all blood types in preterm and term infants (P < 0.01 for all). CONCLUSIONS: We found that the serum ALP levels measured using the IFCC method could be calculated as 0.34 times the ALP levels measured using the JSCC method in preterm and term infants with any blood type: ALP levels (IFCC method) = 0.34 × ALP levels (JSCC method).

Severe Bronchopulmonary Dysplasia Adversely Affects Brain Growth in Preterm Infants.

INTRODUCTION: Bronchopulmonary dysplasia (BPD) is associated with neurodevelopmental outcomes of preterm infants, but its effect on brain growth in preterm infants after the neonatal period is unknown. This study aimed to evaluate the effect of severe BPD on brain growth of preterm infants from term to 18 months of corrected age (CA). METHODS: Sixty-three preterm infants (42 with severe BPD and 21 without severe BPD) who underwent magnetic resonance imaging at term equivalent age (TEA) and 18 months of CA were studied by using the Infant Brain Extraction and Analysis Toolbox (iBEAT). We measured segmented brain volumes and compared brain volume and brain growth velocity between the severe BPD group and the non-severe BPD group. RESULTS: There was no significant difference in brain volumes at TEA between the groups. However, the brain volumes of the total brain and cerebral white matter in the severe BPD group were significantly smaller than those in the non-severe BPD group at 18 months of CA. The brain growth velocities from TEA to 18 months of CA in the total brain, cerebral cortex, and cerebral white matter in the severe BPD group were lower than those in the non-severe BPD group. CONCLUSION: Brain growth in preterm infants with severe BPD from TEA age to 18 months of CA is less than that in preterm infants without severe BPD.

Effect of doxapram on the electrical activity of the diaphragm waveform pattern of preterm infants.

OBJECTIVE: This study aimed to evaluate the change in the waveform pattern of the electrical activity of the diaphragm (Edi) following the administration of doxapram in extremely preterm infants ventilated with neurally adjusted ventilatory assist (NAVA). STUDY DESIGN: We conducted this retrospective cohort study in our neonatal intensive care unit between November 2019 and September 2021. The study participants were extremely preterm infants under the gestational age of 28 weeks who were ventilated with NAVA and administered doxapram. We collected the data of the Edi waveform pattern and calculated the proportion. To analyze the change in the proportion of the Edi waveform pattern, we compared the proportion of the data for 1 h before and after doxapram administration. RESULTS: Ten extremely preterm infants were included. Almost all the patients' respiratory condition improved after doxapram administration. The ventilatory parameters-Edi peak, Edi minimum, peak inspiratory pressure, time in backup ventilation, and number of switches to backup ventilation-did not change significantly. However, the proportion of phasic pattern significantly increased (before: 46% vs. after: 72%; p < 0.05), whereas the central apnea pattern significantly decreased after doxapram administration (before: 31% vs. after: 8.3%; p < 0.05). The proportion of irregular low-voltage patterns tended to decrease, albeit with no significant changes. CONCLUSION: Our results indicated that the proportion of Edi waveform patterns changed following doxapram administration. Edi waveform pattern analysis could be a sensitive indicator of effect with other intervention for respiratory conditions.

Effect of electrical activity of the diaphragm waveform patterns on SpO2 for extremely preterm infants ventilated with neurally adjusted ventilatory assist.

OBJECTIVE: This study aimed to evaluate the association between electrical activity of the diaphragm (Edi) waveform patterns and peripheral oxygen saturation (SpO2 ) in extremely preterm infants who are ventilated with neurally adjusted ventilatory assist (NAVA). STUDY DESIGN: We conducted a retrospective cohort study at a level III neonatal intensive care unit. Extremely preterm infants born at our hospital between November 2019 and November 2020 and ventilated with NAVA were included. We collected Edi waveform data and classified them into four Edi waveform patterns, including the phasic pattern, central apnea pattern, irregular low-voltage pattern, and tonic burst pattern. We analyzed the Edi waveform pattern for the first 15 h of collectable data in each patient. To investigate the association between Edi waveform patterns and SpO2 , we analyzed the dataset every 5 min as one data unit. We compared the proportion of each waveform pattern between the desaturation (Desat [+]) and non-desaturation (Desat [-]) groups. RESULTS: We analyzed collected data for 105 h (1260 data units). The proportion of the phasic pattern in the Desat (+) group was significantly lower than that in the Desat (-) group (p < .001). However, the proportions of the central apnea, irregular low-voltage, and tonic burst patterns in the Desat (+) group were significantly higher than those in the Desat (-) group (all p < .05). CONCLUSION: Our results indicate that proportions of Edi waveform patterns have an effect on desaturation of SpO2 in extremely preterm infants who are ventilated with NAVA.