Effect of tilting on cerebral haemodynamics in preterm infants with periventricular leucencephalomalacia

Aim: Measurement of cerebral haemodynamics to detect impaired cerebral blood flow and impaired cerebral autoregulation might make prevention of brain lesions and especially periventricular leucencephalomalacia (PVL) achievable. Methods: Changes in cerebral blood volume (CBV) and the cerebral haemoglobin oxygenation index (cHbD) following tilting up and down in 10 preterm infants with PVL and 25 preterm infants without PVL, measured by near infrared spectroscopy (NIRS), were analysed. Tilting manoeuvres were recorded with a polysomnographic system in combination with NIRS. CBV and cHbD of the baseline phase (1 min before tilting) were compared with data from the post-tilting phase (1 min after tilting). Results: Changes in CBV and cHbD after tilting were significantly pronounced in infants with PVL compared with infants without PVL. CBV decreased in infants with PVL, by -0.099 ± 0.081 ml 100 g ^-1 brain (mean ± SD) after tilting up, and increased by 0.106 ± 0.104 ml 100 g ^-1 brain after tilting down. CBV decreased in infants without PVL, by -0.041 ± 0.068 ml 100 g ^-1 brain after tilting up, and increased by 0.020 ± 0.096 ml 100 g ^-1 brain after tilting down. cHbD showed similar changes after tilting.

Conclusion: Changes in CBV and cHbD after tilting were pronounced in preterm infants with PVL and this may indicate reduced cerebral autoregulatory capacity.     

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.     

应用近红外光谱技术评价早产儿认知功能的探讨

目的：通过建立对早产儿光刺激后的反应模式,评价早产儿早期的认知功能,研究早产儿在发育过程中的脑反应性与足月儿之间的差距。方法：对纠正胎龄3个月、6个月的早产儿进行光刺激,应用近红外光谱技术,观察光刺激后脑反应性的变化,并与同龄儿对照。结果：早产儿在纠正胎龄3个月时,光刺激后开始反应时间、反应高峰出现的时间分别为17.2±5.2s、38.4±9.6s,明显长于足月儿的13.1±2.7s、28.9±5.0s;脑组织还原血红蛋白、氧合血红蛋白、脑组织氧饱和度在刺激后的最大反应值分别为(1.2±0.5)%、(1.5±0.6)%、(1.3±0.4)%,明显低于足月儿的(2.3±0.3)%、(2.8±0.3)%、(2.4±0.5)%。到了纠正胎龄6个月时,光刺激后的脑反应性与足月儿相比,无统计学差异。结论：早产儿在发育过程中,认知功能存在一定的滞后,到纠正胎龄3个月时,外界刺激后的脑反应性仍落后于同龄儿,到了纠正胎龄6个月时,脑反应性接近同龄儿,应加强对早产儿的早期干预。     

Postnatal adaptation of cerebral blood flow using near infrared spectroscopy in extremely preterm infants undergoing high-frequency oscillatory ventilation

Aim: To determine cerebral blood flow using near infrared spectroscopy in extremely preterm infants undergoing high-frequency oscillatory ventilation during the first three days of life. Low cerebral blood flow has been associated with both intra-ventricular haemorrhage and periventricu-lar leucomalacia. It is well established that cerebral blood flow increases over the first three days of life in extremely preterm infants who are conventionally ventilated with intermittent positive pressure ventilation. However, there is no information about cerebral blood flow in preterm babies undergoing high-frequency oscillatory ventilation. In addition, there are concerns that high-frequency oscillatory ventilation may be associated with an increased incidence of intra-ventricular haemorrhage in premature infants. Methods: Thirteen appropriately grown, preterm infants of less than 28 wk gestation who were admitted to the neonatal unit at University College Hospital, London were studied using near infrared spectroscopy. Left ventricular output and right ventricular output were assessed echocardiographically. Results: Extremely preterm infants undergoing high-frequency oscillatory ventilation have remarkably low cerebral blood flow in the first 12 h of life, median 6.7 (range 4.4-11) mls. 100 g[Formula: See Text] min[Formula: See Text] followed by an increase over the subsequent three days. Left ventricular output also increased over the first three days of life, whereas right ventricular output showed no clear relationship with time. Despite low cerebral blood flow only one infant had evidence of major cerebral injury.

Conclusion: Cerebral blood flow is extremely low in this group of preterm babies. Despite this extremely low cerebral blood flow, the clinical outcome is good. There was an increase in cerebral blood flow and a corresponding increase in left ventricular output over the first few days of life.     

A comparison of P02 monitoring techniques in newborn infants

Abstract This study is an evaluation of different methods of Po₂ monitoring in newborn infants. These were an intra-vascular Pb₂ electrode (Searle Life Support Systems); transcutaneous monitoring (Kontron and Hewlett-Packard); and arteriatized capillary blood samples. Values of each were compared with simultaneous aortic sample values and their correlation compared.
The Searle electrode and TCM were found to be of equivalent accuracy overall, although the Searle was less reliable. Searle catheters were more difficult to insert than normal catheters, with a high wastage. Arterialized capillary Po₂ values did not correlate with arterial.
Transcutaneous monitoring is the most reliable and cheapest method.     

Postnatal development of the cerebral blood flow velocity response to changes in CO2 and mean arterial blood pressure in the piglet

Cerebral blood flow velocity was studied during changes (haemorrhage) in mean arterial blood pressure or P _aCO₂ in 56 (aged 0–26 days) anaesthetized and ventilated piglets. The CO₂ reactivity increased with age from 6.5% kPa⁻'(< 1 day) to adult levels of 25% kPa⁻¹ for piglets over 4 days old. The mean arterial blood pressure reactivity was reduced from 1.3% mmHg⁻¹ (< 1 day old) to 0.0%/ mmHg (> 4 days old). The reactivities were similar with two different anesthetics: chloralose/urethane or pentobarbital. To validate the cerebral blood flow velocity data, both electromagnetic flow and precerebral Doppler ultrasound velocity were recorded from the same common carotid artery with extracranial branches tied off. There were no differences between the results with these two methods nor between these results and those obtained when the cerebral blood flow velocities were recorded from an intracerebral artery and the electromagnetic flowmeter recorded from the carotid artery. The vessel diameter appears stable during these interventions. In conclusion, the autoregulatory response and the reaction to P _aCO₂ appear poorly developed in the newborn piglet, but rapidly mature during the first 4 days of life.     

Effects of repeated indomethacin administration on cerebral oxygenation and haemodynamics in preterm infants: Combined near infrared spectrophotometry and Doppler ultrasound study

The objectives of this study were to evaluate the effect of repeated indomethacin administration on cerebral oxygenation in relation to changes in cerebral blood flow velocity (CBFV) and other relevant physiological variables. Fourteen preterm infants with patent ductus arteriosus were studied during three subsequent indomethacin bolus administrations with intervals of 12 and 24 h. Changes in concentration of oxyhaemoglobin (cO₂Hb), deoxyhaemoglobin (cHHb) and oxidized cytochrome aa₃ (cCyt.aa₃) in cerebral tissue and changes in cerebral blood volume (CBV) were measured by near infrared spectrophotometry; changes in mean CBFV in the internal carotid artery were measured by pulsed Doppler ultrasound. Simultaneously heart rate, transcutaneouspO₂ andpCO₂, arterial O₂ saturation and blood pressure were measured. All variables were continuously recorded until 60 min after indomethacin administration. Within 5 min after each indomethacin administration, significant decreases in CBFV, CBV and cO₂Hb and cCyt.aa₃ were observed which persisted for at least 60 min, while cHHb increased or did not change at all. There were no changes in the other variables recorded. These data demonstrate that indomethacin administration is accompanied by a reduction in cerebral tissue oxygenation due to decreased cerebral blood flow. Therefore, low arterial oxygen content, either caused by low arterial O₂ saturation or by low haemoglobin concentration, may be a contraindication for indomethacin treatment in preterm infants.     

Surgical closure of patent ductus arteriosus reduces the cerebral tissue oxygenation index in preterm infants: a near-infrared spectroscopy and Doppler study

BACKGROUND: The aim of this study was to investigate the effects of patent ductus arteriosus (PDA) ligature on cerebral oxygen saturation, cerebral blood volume (CBV) and cerebral blood flow velocity by means of near-infrared spectroscopy (NIRS) and transcranial Doppler simultaneous examinations. METHODS: This is an observational study considering 16 babies of gestational age 24-34 weeks diagnosed with PDA who underwent surgical ligation. The cerebral oxygen saturation, CBV and blood gases values were obtained 35 min before ligation, so also around the 14th and 27th min after the clip's insertion. RESULTS: Cerebral oxygen saturation, measured as tissue oxygenation index (TOI), decreased significantly after PDA ligation from a basal value of 61.1 (3.8) before surgery to 56.6 (3.3) and 55.8 (2.6)%, for the 14th and 27th min, respectively (P<0.04). CBV before and after clipping was unvaried. A negative correlation was found between DeltapH and DeltaCBV after ligation (R=0.52, P=0.03), whilst a positive correlation was found between DeltaCBV and DeltaP(aCO2) (R=0.62, P=0.009). pH increased at the 27th min post-ligation. CONCLUSIONS: NIRS is a tool for obtaining information on cerebral oxygen saturation and CBV changes during surgical PDA ligation at the bedside. A fall in TOI suggests an increased oxygen extraction during PDA surgery. The lack of increase in DeltaCBV or in diastolic flow velocity show that the PDA before the clipping did not limit cerebral blood flow, the drop in TOI suggests increased oxygen consumption over the clip and the need for accurate monitoring of oxygen utilization after the surgical treatment.     

早产儿脑反应性及其神经发育的近红外光谱评价研究

目的研究早产儿脑对外界刺激的反应性与神经发育的关系,早期对早产儿进行脑功能的评价,为了解其神经发育水平、估价预后提供客观证据。方法对不同胎龄的早产儿进行声刺激,用近红外光谱技术,观察声刺激后脑反应性的变化,并进行神经发育随访,评价早产儿早期脑反应性与其后神经发育的关系。结果本组早产儿生后对声刺激均显示出不同程度的反应,30~32周的早产儿声刺激后开始反应时间、高峰出现时间、停止刺激后开始恢复时间分别为(278±94)s、(446±67)s、(199±52)s,明显长于足月儿的(107±30)s、(264±51)s、(131±46)s。氧合血红蛋白、还原血红蛋白、脑组织氧饱和度的最大反应值分别为(0.3±0.3)%、(0.7±0.5)%、(0.3±0.3)%,明显低于足月儿的(1.7±0.7)%、(1.7±0.8)%、(1.6±0.7)%。胎龄大于32周的早产儿反应的时间及最大反应值与足月儿相比,差异无统计学意义。围产期脑损伤可影响脑的反应性,早产儿脑反应性与纠正胎龄40周时的神经行为评分及神经发育相关。随访过程中颅脑超声表现为脑发育异常者,其新生儿期对声刺激无反应的比例明显高于脑发育正常者。结论近红外光谱技术能评价新生儿的脑反应性,早产儿具备对声刺激后的脑反应性,早期的脑反应性与神经发育水平有关。     

Cerebral hemodynamics during arousals in preterm infants

The aim of the study was to evaluate potential changes of cerebral blood volume (CBV) related to arousals in preterm infants. As arousals are known to change different physiological parameters, it was postulated that this could also hold true for CBV. Polygraphic recordings were performed in 38 preterm infants (18 female, 20 male). The infants' gestational age at birth was 32.0+/-2.3 weeks, postconceptional age was 35.1+/-1.2 weeks and postnatal age at study entry was 24.3+/-2.9 days, birth weight was 1793+/-527 g and actual weight at study entry was 2011+/-324 g [mean (+/- standard deviation)]. CBV was measured using near infrared spectroscopy. Arousals were scored due to the guidelines of the "International Paediatric Work Group on Arousals" and categorized as either cortical (CA) or subcortical arousals (SCA). Altogether, 122 arousals (66 CA, 56 SCA) were scored. According to sleep stage, 77 arousals were analyzed in active sleep, 23 in quiet sleep and 22 in intermediate sleep. Mean duration of arousals was 8.8+/-0.3 s. CBV, cerebral vascular oxygenation and the balance between oxygen delivery and oxygen consumption remained constant during arousals in preterm infants. This was demonstrated for both CA and SCA and was independent of sleep stage, suggesting that the impact of arousals in stable preterm infants is too small to alter cerebral vascular autoregulation.     

Acute Effects of Acetazolamide on Cerebral Blood Flow Velocity and pCO2 in the Newborn Infant

ABSTRACT. Twelve infants with hydrocephalus were treated with acetazolamide. In those treated intravenously middle cerebral artery blood flow velocity increased by a median of 86% (range 54-150%). Maximum increase was reached within 2-20 min. The effect lasted as long as 3.5 hours. Intracranial pressure rose by a median of 4 mmHg (range 0–10 mmHg). There was no significant alteration in blood pressure or heart rate. Respiratory rate increased by approximately 10 breaths/min and the tcpCO₂, rose by a median 0.2 kPa in infants with normal lungs. In infants treated orally, blood velocity rose by 35-40% at 60-80 min with no increase in intracranial pressure. In four infants with lung disease pCO₂, rose by a median of 2.0 kPa (range 0.6 to 3.4 kPa). Acetazolamide was well tolerated in infants with normal lungs but should be used with caution in the presence of lung disease.     

The Value of the Sinusoidal tcPO2 Pattern in the Evaluation and Management of Cyanotic Congenital Heart Disease with Ductus Dependent Lesions

A characteristic sinusoidal tcPO₂ pattern was observed in 17(27%) of 62 patients with congenital heart disease manifested by cyanosis or heart failure during the neonatal period. All of these 17 patients were definitively diagnosed by cardiac catheterization, as having 8 PPA; 3 ToF; 2 TCA+VSD+PA; 2 asplenia with PA; 1 TGA+VSD+PS; and 1 TA (no TCA type). The transcutaneous oxygen pressure pattern of these patients showed a sinusoidal change with a cycle length of 6–20 min with the maximum pressure not exceeding 50 torr and the minimum pressure occasionally close to 0 torr. This sinusoidal tcPO₂ pattern was associated with various types of ductus-dependent congenital heart diseases and hence may be of diagnostic value. Transcutaneous oxygen pressure monitoring is also useful in evaluating the ductal response to PG. Other possible mechanisms underlying this phenomenon including biological oscillation should be considered.