Measuring gut perfusion and blood flow in neonates using ultrasound Doppler of the superior mesenteric artery: a narrative review.

The gut is a relatively silent organ in utero but takes on a major role after birth for the absorption and digestion of feed for adequate nutrition and growth. The neonatal circulation undergoes a transition period after birth, and gut perfusion increases rapidly to satisfy the oxygen demand and consumption. If this process is compromised at any stage, preterm and fetal growth restricted infants are at particular risk of gut tissue injury secondary to hypoxia, leading to necrotizing enterocolitis. Feeding can also be a challenge in these high-risk groups due to gut dysmotility. Superior mesenteric artery (SMA) Doppler is a safe, bedside investigation that could rapidly aid clinicians with feeding strategies and in monitoring high-risk infants. This article aims to establish normal patterns of gut blood flow velocity in neonates using SMA Doppler and reviews how it might be used clinically in pathologic states.

Abdominal Near Infrared Spectroscopy can be reliably used to measure splanchnic oxygenation changes in preterm infants.

OBJECTIVE: Near-infrared spectroscopy (NIRS) allows assessment of regional tissue oxygen delivery and extraction. There are doubts regarding reliability of gut NIRS measurements. This study assesses reliability of NIRS for monitoring gut oxygenation. STUDY DESIGN: Splanchnic tissue haemoglobin index (sTHI), tissue oxygenation index (sTOI) and fractional tissue oxygen extraction (sFTOE) changes during blood transfusion were measured using NIRS and compared to stable control infants. Infants were grouped into 3 chronological age groups: 1-7, 8-28 and ≥29 days of life. RESULTS: sTHI, sTOI significantly increased, and sFTOE reduced following blood transfusion in all age group infants (n = 59), with no changes seen in control infants (n = 12). Baseline characteristics including gestational age and feed volumes did not differ between groups. CONCLUSION: Gut perfusion measured by NIRS improved in infants who received blood transfusion, a change not seen in the control group, thus suggesting NIRS is a reliable method to measure splanchnic tissue oxygenation.

Demand for regional level III neonatal services is not reduced during national COVID lockdowns.

Following the first peak of the COVID-19 pandemic, reports from around the world suggested a reduction in preterm deliveries during lockdown periods. We reviewed preterm admissions to a large tertiary neonatal unit in inner North East London during two United Kingdom (UK) national lockdowns in 2020 and 2021. We found no evidence of difference in admissions during two national lockdowns compared to previous years. Based on these findings, we recommend that neonatal services remain as vigilant and prepared as ever for the unpredictable nature of preterm birth, and their staff protected to provide this highly specialist care.

Blood transfusion in preterm infants improves intestinal tissue oxygenation without alteration in blood flow.

BACKGROUND AND OBJECTIVE: The objective of the study was to investigate the splanchnic blood flow velocity and oximetry response to blood transfusion in preterm infants according to postnatal age. MATERIALS AND METHODS: Preterm infants receiving blood transfusion were recruited to three groups: 1-7 (group 1; n = 20), 8-28 (group 2; n = 21) and ≥29 days of life (group 3; n = 18). Superior mesenteric artery (SMA) peak systolic (PSV) and diastolic velocities were measured 30-60 min pre- and post-transfusion using Doppler ultrasound scan. Splanchnic tissue haemoglobin index (sTHI), tissue oxygenation index (sTOI) and fractional tissue oxygen extraction (sFTOE) were measured from 15-20 min before to post-transfusion using near-infrared spectroscopy. RESULTS: The mean pretransfusion Hb in group 1, 2 and 3 was 11, 10 and 9 g/dl, respectively. The mean (SD) pretransfusion SMA PSV in group 1, 2 and 3 was 0·63 (0·32), 0·81 (0·33) and 0·97 (0·40) m/s, respectively, and this did not change significantly following transfusion. The mean (SD) pretransfusion sTOI in group 1, 2 and 3 was 36·7 (19·3), 44·6 (10·4) and 41·3 (10·4)%, respectively. The sTHI and sTOI increased (P < 0·01), and sFTOE decreased (P < 0·01) following transfusion in all groups. On multivariate analysis, changes in SMA PSV and sTOI following blood transfusion were not associated with PDA, feeding, pretransfusion Hb and mean blood pressure. CONCLUSION: Pretransfusion baseline splanchnic tissue oximetry and blood flow velocity varied with postnatal age. Blood transfusion improved intestinal tissue oxygenation without altering mesenteric blood flow velocity irrespective of postnatal ages.

Cerebral blood flow and oximetry response to blood transfusion in relation to chronological age in preterm infants.

OBJECTIVE: Preterm infants frequently receive blood transfusion (BT) and the aim of this study was to measure the effect of BT on cerebral blood flow and oxygenation in preterm infants in relation to chronological age. PATIENTS: Preterm infants undergoing intensive care recruited to three chronological age groups: 1 to 7 (Group 1; n=20), 8 to 28 (Group 2; n=21) & ≥29days of life (Group 3; n=18). METHODS: Pre and post-BT anterior cerebral artery (ACA) time averaged mean velocity (TAMV) and superior vena cava (SVC) flow were measured. Cerebral Tissue Haemoglobin Index (cTHI) and Oxygenation Index (cTOI) were measured from 15-20min before to 15-20min post-BT using NIRS. Vital parameters and blood pressure were measured continuously. RESULTS: Mean BP increased significantly, and there was no significant change in vital parameters following BT. Pre-BT ACA TAMV was higher in Group 2 and 3 compared to Group 1 (p<0.001). Pre-BT ACA TAMV decreased significantly (p≤0.04) in all 3 groups; pre-BT SVC flow decreased significantly in Group 1 (p=0.03) and Group 3 (p<0.001) following BT. Pre-BT cTOI was significantly lower in Group 3 compared to Group 1 (p=0.02). cTHI (p<0.001) and cTOI (p<0.05) increased significantly post-BT in all three groups. PDA had no effect on these measurements. CONCLUSION: Baseline cTOI decreases and ACA TAMV increases with increasing chronological age. Blood transfusion increased cTOI and cTHI and decreased ACA TAMV in all groups. PDA had no impact on the baseline cerebral oximetry and blood flow as well as changes following blood transfusion.

Thinking outside of the blue box: a case presentation of neonatal methemoglobinemia.

We report the case of a full-term neonate who presented with cyanosis from birth secondary to methemoglobinemia precipitated by the obstetric use of bupivacaine in a spinal anaesthetic for caesarean delivery.

Palliative care for the newborn in the United Kingdom.

Palliative care for the newborn is a developing area. There are more than 2000 estimated neonatal deaths each year in the UK from causes likely to benefit from palliative care. There is an increasing recognition that while the goals of care may be different for dying newborns, they deserve the same high standard of care as those babies who go on to survive. Recent neonatal palliative care guidance is available from the British Association for Perinatal Medicine (BAPM), the General Medical Council (GMC), and ACT (the U.K. association for children's palliative care). We attempt to answer the question: 'What does the provision of good neonatal palliative care look like?' by examining the factors important in the provision of such care.

Neonatal nephrocalcinosis: long term follow up.

AIMS: To assess the spontaneous resolution of neonatal nephrocalcinosis and its long term effects on renal function. METHODS: Fourteen very low birthweight preterm babies with nephrocalcinosis were followed up at 5-7 years of age; 14 controls were matched for sex, gestation, and birth weight. Height, weight, blood pressure, and renal symptomatology were recorded, and a renal ultrasound scan was performed. Early morning urine osmolality and creatinine ratios of albumin, phosphate, calcium, oxalate and beta microglobulin were determined. Urea and electrolytes in the study group were determined, and glomerular filtration rate (GFR) and TmP/GFR (tubular reabsorption of phosphate per GFR) were calculated. Statistical analysis was performed on a group basis using the Mann-Whitney confidence interval. RESULTS: Mean age was 6.9 years (range 5.81-7.68). An early morning urine osmolality >700 mOsm/kg was achieved in all cases. In two cases and four controls, the calcium/creatinine ratio was >0.7 mmol/mmol. In all cases, the GFR was normal (median 132.6 ml/min/1.73 m(2) (range 104.1-173.1)). Median TmP/GFR was 1.22 mmol/l (0.73-1.61), with two having levels below the normal range. These did not have persisting nephrocalcinosis. Nephrocalcinosis was found in three of the 12 cases scanned and one control. There were no significant differences in urine biochemistry. CONCLUSIONS: Resolution of nephrocalcinosis occurred in 75% of cases. No evidence was found to suggest that nephrocalcinosis is associated with renal dysfunction in the long term. There was evidence of hypercalciuria in the cases and controls, suggesting that prematurity may be a risk factor.

Jejunal atresia in an infant with triple-X syndrome.

A 33-year-old woman presented at 31 weeks' gestation with polyhydramnios that required repeated amniodrainage. An antenatal scan at 32 weeks showed dilated fetal bowel loops, which were not confirmed on subsequent scans. The amniotic fluid karyotype confirmed 47,XXX. After birth, jejunal obstruction was confirmed. To our knowledge, this is the first report of an association of triple-X syndrome and jejunal atresia.

Decision making and modes of death in a tertiary neonatal unit.

AIMS: To study the frequency and reason for withdrawal/withholding of life sustaining treatment (LST) and do not resuscitate (DNR) orders in infants who died in a tertiary neonatal unit. METHODS: Infants who died at Homerton University Hospital between January 1998 and September 2001 were studied by retrospective analysis of patient records. RESULTS: The case notes of 71 (84%) of 85 infants who died were studied. Mode of death was withdrawal of LST in 28 (40%), DNR in 11 (15%), withholding of LST in two (3%), and natural in 30 (42%) infants. Withdrawal of LST was discussed with the parents of 39 seriously ill infants; 28 (72%) parents agreed. There was no difference in birth weight and gestational age of babies whose parents agreed or refused withdrawal of LST. White and Afro-Caribbean parents and those from the Indian subcontinent (20 of 23) were more likely to agree to withdrawal of LST than Black African or Jewish (eight of 16, p = 0.015) parents. The median age at withdrawal of LST was 4 days (range 1-57). The median duration between discussion and the parents agreeing to withdrawal of LST was 165 minutes (range 30-2160), and median duration between withdrawal of LST and death was 22 minutes (range 5-210). The most common reason for withdrawal of LST was complications of extreme prematurity (68%). CONCLUSION: The most common mode of death was withdrawal of LST, and the most common reason was complications of extreme prematurity. The ethnic and cultural background of the parents influenced agreement to withdrawal of LST.

Neonatal hypopituitarism presenting with poor feeding, hypoglycemia and prolonged unconjugated hyperbilirubinemia.

The association between neonatal hypopituitarism and unconjugated hyperbilirubinemia has rarely been documented. We report a female infant who presented with persistent poor feeding, episodic borderline hypoglycemia and prolonged unconjugated hyperbilirubinemia; investigation revealed hypopituitarism. The diagnosis of hypopituitarism should therefore be considered in neonates presenting with prolonged unconjugated hyperbilirubinemia.

Is it possible to predict the blood volume of a sick preterm infant?

OBJECTIVE: To investigate the relation between the measured intravascular blood volume (BV) and current methods of indirectly assessing BV status in sick preterm infants on the first day of life. METHODS: Thirty eight preterm infants of gestation 24-32 weeks (median 30) and weight 480-2060 g (median 1220) were studied. Red cell volume was measured by the fetal haemoglobin dilution method in six infants and by the biotin labelled autologous red cell dilution method in the remaining 32. Total BV was calculated by dividing red cell volume by packed cell volume. Indirect assessments of BV status using heart rate (HR), core-peripheral temperature difference, mean arterial pressure, base excess, and packed cell volume were recorded. RESULTS: The mean (SD) initial measured BV was 71 (12) ml/kg (range 53-105). The mean HR was 148 beats/min (range 130-180), which correlated positively (r = 0.39, p = 0.02) with BV (higher HR was associated with higher BV). The mean base excess was -3.19 mmol/l (range -18 to +6.2). The negative base excess correlated significantly positively (r = 0.41, p < 0.01) with BV (more acidotic babies tended to have higher BV). There was no significant correlation between core-peripheral temperature difference, mean arterial pressure, or packed cell volume and BV. Regression analysis showed that base excess and HR were significantly related to BV; base excess alone can predict variability in BV only to 17%, and base excess with HR can predict variability in BV to 29%. CONCLUSION: The conventional clinical and laboratory indices are poor predictors of measured blood volume.

A preterm baby with Omenn syndrome.

UNLABELLED: A preterm baby born with scaly skin who later developed recurrent infections and was subsequently diagnosed to have Omenn syndrome is presented. CONCLUSION: Any baby with ichthyotic skin and recurrent infections should have immunodeficiency considered in the differential diagnosis.