Hajime Yasuhara

Effective method for screening for respiratory inhibition after crying in infants

Background:  In order to establish an effective screening method for respiratory inhibition after crying (RIAC), we prospectively studied the correlations between infant RIAC and perinatal factors.

Polygraphic findings of 47 cases with respiratory inhibition after crying

Abstract Objective: To report the polygraphic findings of infants with respiratory inhibition after crying (RIAC). Methods: We screened for RIAC among infants with a gestational age ≥36 weeks using our established method with cranial ultrasonography, SpO2 monitoring and polygraphy. RIAC is defined as central apnea that occurred immediately after crying with a decrease in SpO2 to <60%, followed by repeated irregular respiration and apnea as the respiration gradually recovered. The subjects were infants with RIAC for whom we could study the polygraphic findings in detail. Results: Forty-seven RIAC cases were included in the present analysis. The frequency of RIAC was 2.1 (1.2–7.0) times per 24 h. The maximum duration of respiratory inhibition was 78.0 (52.6–109.0) s. The maximum duration of SpO2 <60% during RIAC was 39.0 (9.8–93.2) s. The minimum SpO2 value during RIAC was 53.0% (42.2–58.0%). The minimum heart rate during RIAC was 103.0 (79.1–127.1) bpm. Conclusions: RIAC is observed among healthy infants, and they experience repeated prolonged hypoxemia.

Timing of injury in utero causing respiratory inhibition after crying.

Background:  The aim of this study was to clarify the timing of injuries in utero that cause respiratory inhibition after crying (RIAC). We evaluated infants with cranial ultrasound abnormalities diagnosed during hospitalization.

Respiratory inhibition after crying and feeding hypoxemia in infants

Abstract Objective: To determine the incidence, risk factors and natural history of respiratory inhibition after crying (RIAC) and feeding hypoxemia. Methods: We screened for RIAC and feeding hypoxemia among 393 infants with a gestational age ≥ 36 weeks using pulse oximetry. Twenty-seven infants were treated in the neonatal intensive care unit. Results: RIAC and feeding hypoxemia were observed in 95 (24.2%) and 124 (31.6%) infants, respectively. RIAC correlated with feeding hypoxemia (p < 0.001), grade II increased echogenicity in the ganglionic eminence (p = 0.005), dilation of the lateral ventricle (p = 0.044), threatened premature labor (p = 0.033) and twin gestation (p = 0.089). Feeding hypoxemia correlated with RIAC (p < 0.001), abnormal cranial ultrasound findings (p < 0.001), maternal smoking during pregnancy (p = 0.083), asymmetric intrauterine growth restriction (p = 0.012) and twin gestation (p = 0.067). All infants recovered from RIAC in an average of 4.5 (2.0–7.0) d. Fifteen infants recovered from feeding hypoxemia, but 10 infants needed additional assistance and monitoring by nursing until the day of discharge. The day of discharge was day 8.0 (5.0–12.4). Conclusions: RIAC and feeding hypoxemia are observed among healthy infants, and these infants experience repeated events of prolonged hypoxemia.

Might asphyxia cause respiratory inhibition after crying in mature infants

Background:  To clarify the timing of injury in utero causing respiratory inhibition after crying (RIAC), the relationship between asphyxia and RIAC was investigated in infants whose gestational age was ≥36 weeks.

Gastroesophageal reflux related to respiratory inhibition after crying and feeding hypoxemia in infants

Abstract Objective: To determine the relationships between gastroesophageal reflux (GER) and both respiratory inhibition after crying (RIAC) and feeding hypoxemia in infants. Methods: We screened for RIAC and feeding hypoxemia among infants with a gestational age of 36 weeks or greater using pulse oximetry. We investigated the infants who showed hypoxemia with a decrease in SpO2 to less than 70% and bradycardia with a heart rate of less than 100 beats per minute caused by GER. We then evaluated the relationships between these events and both RIAC and feeding hypoxemia. Results: We examined 250 infants in the present study. RIAC and feeding hypoxemia were observed in 35 (14.0%), and 30 (12.0%) infants, respectively. Ten infants showed hypoxemia and bradycardia caused by GER. These events were correlated with RIAC (p = 0.006) and feeding hypoxemia (p = 0.031). Conclusions: In the infants with RIAC and feeding hypoxemia, some show severe hypoxemia and bradycardia caused by GER. Medical staff caring for infants should note the presence of RIAC and feeding hypoxemia.

Clinical significance of slightly lateral ventricular enlargement in healthy infants

Abstract Objective: The aim of this study was to determine the clinical significance of slightly lateral ventricular enlargement. Methods: We examined 1151 infants with a gestational age of 36 weeks or greater. We assessed for the presence of ventricular enlargement when apparent space was observed in the frontal horn or body of lateral ventricle by a transfontanel ultrasound scan. Results: Two hundred and forty-eight infants had ventricular enlargement. The atrial widths in most infants were less than 10 mm. Ventricular enlargement correlated with Cesarean delivery, gestational age, birth weight, respiratory disturbance at delivery and respiratory inhibition after crying (RIAC). Ventricular enlargement could be divided into three types by ultrasound findings. Forty-five infants showed only enlargement of the anterior horn (Type A), 97 infants showed enlargement from the body to the posterior horn (Type B), and 108 infants showed whole enlargement from the anterior to the posterior horn (Type C). The infants with Type A correlated with intrauterine growth restriction, placenta previa, male gender and birth weight. The infants with Type B correlated with cesarean delivery. The infants with Type C correlated with diabetes mellitus, respiratory disturbance at delivery, RIAC and feeding hypoxemia. Conclusions: Slightly lateral ventricular enlargement should be considered clinically significant.

Asymmetric intrauterine growth restriction is a risk factor for respiratory inhibition after crying in infants

Abstract Objective: We investigated whether intrauterine growth restriction (IUGR) correlated with respiratory inhibition after crying (RIAC) and feeding hypoxemia. Methods: We screened for RIAC among 1248 infants with a gestational age ≥36 weeks using our established method with cranial ultrasound, SpO2 monitoring, and polygraphy. We classified the infants into three groups: symmetric IUGR, asymmetric IUGR, and control. We compared the perinatal factors with the incidence of RIAC and feeding hypoxemia among the three groups. Results: Overall, 26 infants had symmetric IUGR, 143 infants had asymmetric IUGR, and 1079 infants were in the control group. RIAC was observed in 10 (6.9%) infants in the asymmetric IUGR group and in 37 (3.4%) infants in the control group. Feeding hypoxemia was observed in 15 (10.5%) infants in the asymmetric IUGR group and in 52 (4.8%) infants in the control group. The incidence of RIAC and feeding hypoxemia in the asymmetric IUGR group was significantly more than that in the control group. None of the infants with symmetric IUGR exhibited RIAC or feeding hypoxemia. Conclusions: The results indicate that asymmetric IUGR is a risk factor for RIAC and feeding hypoxemia. These infants should be aggressively screened for RIAC.

A speculated cause of respiratory inhibition in infants

Abstract Objective: In our previous studies, we documented that threatened premature labor and asymmetrical intrauterine growth restriction were risk factors for respiratory inhibition. The goal of this study was to determine the cause of respiratory inhibition by considering perinatal risk factors. Methods: We examined 1497 infants with a gestational age of 36 weeks or greater. All infants were monitored using pulse oximetry and examined via cranial sonography. Respiratory inhibition was defined as severe hypoxemia caused by respiratory inhibition immediately after crying or gastroesophageal reflux or as a respiratory pause during feeding. We examined the relationships between respiratory inhibition and perinatal factors and speculated on the cause of respiratory inhibition. Results: The median gestational age, birth weight, Apgar score at 1 min, and Apgar score at 5 min of the subjects were 38.9 weeks, 2930 g, 8.0 points, and 9.0 points, respectively. Respiratory inhibition was observed in 422 infants. Lateral ventricle enlargement and increased echogenicity in the ganglionic eminence were observed in 417 and 516 infants, respectively. Respiratory inhibition was significantly correlated with shorter gestational periods, twin pregnancies, lateral ventricle enlargement, and increased echogenicity in the ganglionic eminence. Conclusions: We speculate that umbilical cord compression is a major cause of respiratory inhibition.

Efficacy of routine catheter tip culture in a neonatal intensive care unit

Routine catheter tip cultures are not recommended because some cases of colonization, such as with Staphylococcus aureus, can lead to subsequent bacteremia. To evaluate the safety of colonization without antimicrobial treatment, as well as the effectiveness of routine catheter tip cultures in the neonatal intensive care unit (NICU), we performed a retrospective data analysis in a Japanese community hospital.