Publications by authors named "Kogoro Iwanaga"

4 Publications

  • Page 1 of 1

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

Pediatr Pulmonol 2021 Jul 6;56(7):2094-2101. Epub 2021 Apr 6.

Department of Pediatrics, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

Objective: This study aimed to evaluate the association between electrical activity of the diaphragm (Edi) waveform patterns and peripheral oxygen saturation (SpO ) 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 SpO , 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 SpO in extremely preterm infants who are ventilated with NAVA.
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http://dx.doi.org/10.1002/ppul.25396DOI Listing
July 2021

Signal Intensity and Volume of Pituitary and Thyroid Glands in Preterm and Term Infants.

J Magn Reson Imaging 2021 04 16;53(4):1151-1161. Epub 2020 Oct 16.

Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

Background: Hypothalamic-pituitary-thyroid (HPT) maturation has not been extensively evaluated using neonatal MRI, even though both structures are visualized on MRI.

Hypothesis: That signal intensity and volume of pituitary and thyroid (T) glands on MRI in neonates may be interrelated.

Study Type: Retrospective.

Subjects: In all, 102 participants.

Field Strength/sequence: 3.0T, T -weighted pointwise encoding time reduction with radial acquisition (PETRA).

Assessment: The volume of interest of the anterior pituitary (AP), posterior pituitary (PP), and T on MRI were defined on T -PETRA by two radiologists, and volumes of AP (AP_vol) and thyroid (T_vol) were calculated. Gestational age (GA), chronological age (CA), GA+CA, birth weight (BW), and thyroid function were recorded. Mean and maximum signal intensities of AP, PP, and T were normalized using signals from the pons and spinal cord as follows: signal ratio of anterior pituitary/pons (AP/pons), signal ratio of posterior pituitary/pons (PP/pons), and signal ratio of thyroid/cord (T/cord) T/cord, respectively.

Statistical Tests: Correlations between signal intensity and volume measures and GA, CA, GA+CA, and BW were assessed using Pearson's correlation coefficient or Spearman's rank correlation coefficient. Thyroid function analysis and T /cord, T /cord, and T_vol were evaluated using the Steel-Dwass test.

Results: AP /pons correlated positively with GA (ρ = 0.62, P < 0.001) and BW (ρ = 0.74, P < 0.001), and negatively with CA (ρ = -0.86, P < 0.001) and GA+CA (ρ = -0.46, P < 0.001). PP /pons correlated positively with GA (ρ = 0.49, P < 0.001) and BW (ρ = 0.63, P < 0.001), and negatively with CA (ρ = -0.70, P < 0.001) and GA+CA (r = -0.38, P < 0.001). T /cord correlated positively with GA (ρ = 0.48, P < 0.001) and BW (ρ = 0.55, P < 0.001), and negatively with CA (ρ = -0.59, P < 0.001) and GA+CA (ρ = -0.22, P = 0.03). AP_vol correlated positively with GA (ρ = 0.68, P < 0.001) and BW (ρ = 0.73, P < 0.001), and negatively with CA (ρ = -0.72, P < 0.001). T_vol correlated positively with GA (ρ = 0.50, P < 0.001) and BW (ρ = 0.61, P < 0.001), and negatively with CA (ρ = -0.54, P < 0.001). AP /pons correlated positively with T /cord (ρ = 0.61, P < 0.001).

Data Conclusion: Signal and volume of pituitary and thyroid glands correlated positively with GA and BW, and negatively with CA in neonates.

Level Of Evidence: 4 TECHNICAL EFFICACY STAGE: 5.
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http://dx.doi.org/10.1002/jmri.27395DOI Listing
April 2021

Antenatal corticosteroids for threatened labour facilitate thyroid maturation among preterm neonates.

Clin Endocrinol (Oxf) 2020 11 14;93(5):613-619. Epub 2020 Jul 14.

Department of Pediatrics, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

Objective: To examine the effect of antenatal corticosteroids (ANS) on the maturation of thyroid function in the preterm infants.

Context: ANS reduce mortality and morbidities in preterm neonates. Organ maturation by the glucocorticoids is the key, at least in part. However, the effect of ANS on thyroid is controversial.

Patients: A study group of 99 very low birthweight neonates (<34 weeks' gestational age) with the exception of those born more than 7 days after ANS administration were divided into a complete group (n = 49) whose mothers completed two doses of betamethasone and who were born more than 24 hours after the completion of ANS administration, and an incomplete group (n = 50) who were not exposed to any ANS or were born within 24 hours after the completion of ANS administration. Serum-free thyroxine and thyroid-stimulating hormone (TSH) levels were measured, and thyrotropin-releasing hormone (TRH) stimulation tests were performed at about 2 weeks of age.

Results: The incidence of hyperthyrotropinaemia (TSH > 15 mIU/L) in the complete group was significantly lower than in the incomplete group (6% vs 22%, P = .023). Exaggerated responses to TRH tests were more frequent in the incomplete group (17% vs 44%; P = .053). TSH was significantly lower in the complete group, (P = .046). Multivariate logistic regression analysis showed that the incidence of hyperthyrotropinaemia was associated with complete ANS administration (adjusted odds ratios 0.39).

Conclusions: ANS administration might facilitate thyroid maturation in preterm neonates.
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http://dx.doi.org/10.1111/cen.14272DOI Listing
November 2020

Response of preterm infants with transient hypothyroxinaemia of prematurity to the thyrotropin-releasing hormone stimulation test is characterized by a delayed decrease in thyroid-stimulating hormone after the peak.

Clin Endocrinol (Oxf) 2020 11 21;93(5):605-612. Epub 2020 Jun 21.

Department of Pediatrics, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

Objectives: We evaluated the response to the thyrotropin-releasing hormone (TRH) stimulation test in very low-birth weight (VLBW) infants to elucidate the aetiology of transient hypothyroxinaemia of prematurity (THOP).

Design And Methods: We performed TRH stimulation tests on 43 VLBW infants. Subjects were divided into two groups; a THOP group (N = 11; basal TSH < 15 mU/L and basal FT4 ≤ 0.8 ng/dL) and a non-THOP group (N = 32; basal TSH < 15 mU/L and basal FT4 > 0.8 ng/dL). Basal FT4 and FT3 were measured before, and TSH (0, 30, 60, 90, 120 and 180 minutes) was measured after, the administration of TRH (7 µg/kg). We calculated the ratio of TSH 180 minutes to THS 0 minute as the primary outcome. We also collected data on T3 and rT3 in this study.

Results: In both groups, TSH 30 minutes values were the highest. However, the ratios of TSH 180 minutes to THS 0 minutes in the non-THOP group and the THOP group were (median [IQR]) 1.3 [1.0-1.7] and 3.0 [1.5-5.3] (P < .01). No significant differences were observed in T3 (1.0 [0.8-1.3] and 0.7 [0.4-0.7] ng/mL, P = .06). However, in the THOP group, rT3 was significantly lower than that of the non-THOP group (168.0 [148.1-197.0] and 92.9 [74.7-101.6] pg/mL, P < .01).

Conclusions: The delayed decrease in the TSH concentration after the peak for the TRH tests and decreased levels of rT3 suggest that the main aetiology for THOP is suppression at the level of the hypothalamus, but not inactivation of peripheral thyroid hormone metabolism.
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http://dx.doi.org/10.1111/cen.14260DOI Listing
November 2020
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