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. METHODS: We retrospectively examined the medical records of preterm infants who were treated in the neonatal intensive care unit at Nara Prefectural Hospital in Nara, Japan from January 2006 through December 2010. Inclusion criterion was gestational age less than 34 weeks. We evaluated the perinatal factors and cranial ultrasound abnormalities associated with RIAC, feeding hypoxemia, and prolonged apnea. We also evaluated the timing of appearance of cranial ultrasound abnormalities. RESULTS: A total of 125 infants were examined. Mean gestational age was 30.6 ± 2.4 weeks and mean birthweight was 1465 ± 454 g. The numbers of infants who showed RIAC, feeding hypoxemia, and prolonged apnea were 44, 48, and 63, respectively. Among 91 infants who showed cranial ultrasound abnormalities, 67 had increased echogenicity in the ganglionic eminence (GE). There was a significant correlation between increased echogenicity and RIAC (P < 0.001). Of the infants who showed increased echogenicity in the GE, 19 had this finding during the course of hospitalization. In these 19 infants, however, gestational age of those with RIAC was less than 31 weeks. CONCLUSION: We speculate that the timing of intrauterine injury resulting in RIAC in infants is less than 31 gestational weeks.

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. METHODS: RIAC and cranial ultrasound abnormalities were examined for retrospectively in infants treated in the neonatal intensive care unit from April 2004 through March 2009. All included infants were gestational age ≥ 36 weeks and had an Apgar score <4 points at 1 min. The relationship between RIAC and perinatal factors was also examined. RESULTS: Twenty-six infants were included. Three infants had RIAC, seven infants had poor prognosis, and nine infants had ultrasound abnormalities in the ganglionic eminence (GE). There was a significant relationship between RIAC and ultrasound abnormalities in the GE (P= 0.032). Poor prognosis was significantly associated with low Apgar score at 5 min (P ≤ 0.001), disseminated intravascular coagulation (P= 0.047), hypoxic ischemic encephalopathy (P= 0.028), and brain hypothermia therapy (P= 0.028). There was no significant relationship between RIAC and poor prognosis. All infants had ultrasound abnormalities in the GE on the day of birth. CONCLUSION: Damage occurring in utero prior to 36 weeks gestation might cause increased echogenicity or cyst formation in the GE, potentially disturbing maturation of the respiratory center with the development of RIAC.

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. METHODS: We monitored infants (n=141) born from May through July 2009 with polygraphy and evaluated the presence of RIAC and respiratory pause that occurred when feeding was initiated immediately after crying with a decrease in oxygen saturation (SpO(2) ) to <60%. The infants were screened for increased echogenicity, a cyst in the ganglionic eminence (GE), or a subependymal cyst by cranial ultrasound. Furthermore, we evaluated the correlations between RIAC and perinatal factors. RESULTS: Eleven infants displayed RIAC and 31 experienced respiratory pause during feeding with a decrease in SpO(2) to <60%. There were no significant correlations between RIAC and perinatal factors. Forty infants had ultrasound abnormalities (increased echogenicity in the GE, 26; cyst in the GE, nine; and subependymal cyst, seven). Sensitivity, specificity, and efficiency of abnormal cranial ultrasound findings for RIAC were 1.00, 0.777, and 0.794, respectively. The odds ratio, sensitivity, specificity, and efficiency of the combination of abnormal cranial ultrasound findings and respiratory pause during feeding with a decrease in SpO(2) to <60% and RIAC were 35.9 (P<0.001), 0.727, 0.931, and 0.915, respectively. CONCLUSION: The combination of abnormal cranial ultrasound findings and respiratory pause during feeding with a decrease in SpO(2) appears to be an effective method of screening for RIAC.