Blood flow parameters of the superior mesenteric artery as an early predictor of intestinal dysmotility in preterm infants

Site-specific pathophysiology in a neonatal mouse model of gastroparesis

BACKGROUND

Early-life events impact maturation of the gut microbiome, enteric nervous system, and gastrointestinal motility. We examined three regions of gastric tissue to determine how maternal separation and gut microbes influence the structure and motor function of specific regions of the neonatal mouse stomach.

METHODS

Germ-free and conventionally housed C57BL/6J mouse pups underwent timed maternal separation (TmSep) or nursed uninterrupted (controls) until 14 days of life. We assessed gastric emptying by quantifying the progression of gavaged fluorescein isothiocyanate (FITC)-dextran. With isolated rings of forestomach, corpus, and antrum, we measured tone and contractility by force transduction, gastric wall thickness by light microscopy, and myenteric plexus neurochemistry by whole-mount immunostaining.

KEY RESULTS

Regional gastric sampling revealed site-specific differences in contractile patterns and myenteric plexus structure. In neonatal mice, TmSep prolonged gastric emptying. In the forestomach, TmSep increased contractile responses to carbachol, decreased muscularis externa and mucosa thickness, and increased the relative proportion of myenteric plexus nNOS+ neurons. Germ-free conditions did not appreciably alter the structure or function of the neonatal mouse stomach and did not impact the changes caused by TmSep.

CONCLUSIONS AND INFERENCES

A regional sampling approach facilitates site-specific investigations of murine gastric motor physiology and histology to identify site-specific alterations that may impact gastrointestinal function. Delayed gastric emptying in TmSep is associated with a thinner muscle wall, exaggerated cholinergic contractile responses, and increased proportions of inhibitory myenteric plexus nNOS+ neurons in the forestomach. Gut microbes do not profoundly affect the development of the neonatal mouse stomach or the gastric pathophysiology that results from TmSep.

Antenatal Magnesium Sulfate and adverse gastrointestinal outcomes in Preterm infants-a systematic review and meta-analysis

INTRODUCTION

To evaluate the effect of antenatal magnesium sulfate (MgSO4) on mortality and morbidity outcomes related to the gastrointestinal system (GI) in preterm infants.

METHODS

Data sources: A systematic literature search was conducted in November 2022. PubMed, CINAHL Plus with Full Text (EBSCOhost), Embase (Elsevier), and CENTRAL (Ovid) were searched. There were 6695 references. After deduplication, 4332 remained. Ninety-nine full-text articles were assessed and forty four articles were included in the final analysis.

STUDY ELIGIBILITY CRITERIA

Randomized or quasi-randomized clinical trials and observational studies that evaluated at least one of the pre-specified outcomes were included. Preterm infants whose mothers were given antenatal MgSO4 were included and whose mothers did not receive antenatal MgSO4 were the comparators. The main outcomes and measures were: Necrotizing enterocolitis (NEC) (stage ≥ 2), surgical NEC, spontaneous intestinal perforation (SIP), feeding intolerance, time to reach full feeds, and GI-associated mortality.

STUDY APPRAISAL AND SYNTHESIS METHODS

A random-effects model meta-analysis was performed to yield pooled OR and its 95% CI for each outcome due to expected heterogeneity in the studies. The analysis for each predefined outcome was performed separately for adjusted and unadjusted comparisons. All included studies were assessed for methodological quality. The risk of bias was assessed using elements of the Cochrane Collaboration's tool 2.0 and the Newcastle-Ottawa Scale for randomized controlled trials (RCTs) and non-randomized studies (NRS), respectively. The study findings were reported as per PRISMA guidelines.

RESULTS

A total of thirty-eight NRS and six RCTs involving 51,466 preterm infants were included in the final analysis. There were no increased odds of stage ≥2 NEC, (NRS : n = 45,524, OR: 0.95; 95% CI: 0.84-1.08, I2- 5% & RCT's: n = 5205 OR: 1.00; 95% CI: 0.89-1.12, I2- 0%), SIP (n = 34,186, OR: 1.22, 95% CI: 0.94-1.58, I2-30%), feeding intolerance (n = 414, OR: 1.06, 95% CI: 0.64-1.76, I2-12%) in infants exposed to antenatal MgSO4. On the contrary, the incidence of surgical NEC was significantly lower in MgSO4 exposure infants (n = 29,506 OR:0.74; 95% CI: 0.62-0.90, ARR: 0.47%). Studies assessing the effect on GI-related mortality were limited to make any conceivable conclusion. The certainty of evidence (CoE) for all outcomes was adjudged as 'very low' as per GRADE.

CONCLUSION

Antenatal magnesium sulfate did not increase the incidence of gastrointestinal-related morbidities or mortality in preterm infants. With the current evidence concerns, regarding the adverse effects of MgSO4 administration leading to NEC/SIP or GI-related mortality in preterm infants should not be a hurdle in its routine use in antenatal mothers.

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.

Prediction of necrotizing enterocolitis in very low birth weight infants by superior mesenteric artery ultrasound of postnatal day 1: A nested prospective study

BACKGROUND

Necrotizing enterocolitis (NEC) is a devastating intestinal complication that occurs mainly in very-low-birth-weight infants (VLBWI). The study's aim was to investigate the possibility of early prediction of NEC on postnatal day 1 based on superior mesenteric artery (SMA) doppler ultrasonograpy.

METHODS

A prospective, observational, nested case control study (ChiCTR1900026197) was conducted to enroll VLBWIs (birth weight <1,500 grams) between October 2019 and September 2021. Doppler ultrasound measurement was done during the first 12 h of life and before first feeding. Infants developing NEC (stage II or III) subsequently were included in NEC group and infants spare of NEC were included in control group.

RESULTS

370 VLBWIs were enrolled (30 NEC cases). Among the ultrasound parameters, S/D was significantly higher in the NEC group (OR: 2.081, 95% CI: 1.411-3.069, P = 0.000). The area under the receiver operating curve (AUROC) following the Logistic regression was 0.704 (95% CI: 0.566-0.842, P = 0.001). The sensitivity of S/D for predicting NEC was 52.2% and the specificity was 92.7%. The critical value of S/D was 6.944 and Youden index was 0.449. Preplanned subgroup analysis confirmed that NEC infants of different stages were characterized by different SMA bloodstream. Small for gestational age (SGA) might be a confounding factor affecting intestinal bloodflow. And infants with delayed initiation or slow advancement of feeding exhibited characteristic intestinal perfusion.

CONCLUSIONS

In VLBWI, early SMA ultrasound shows the potential to predict NEC. It is reasonable to speculate that SMA bloodstream is related to intestinal structural and functional integrity.

Predicting Infection in Very Preterm Infants: A Study Protocol

BACKGROUND

Neonatal sepsis causes morbidity and mortality in preterm infants. Clinicians need a predictive tool for the onset of neonatal infection to expedite treatment and prevent morbidity. Abnormal thermal gradients, a central-peripheral temperature difference (CPtd) of >2°C or <0°C, and elevated heart rate characteristic (HRC) scores are associated with infection.

OBJECTIVE

This article presents the protocol for the Predictive Analysis Using Temperature and Heart Rate Study.

METHODS

This observational trial will enroll 440 very preterm infants to measure abdominal temperature and foot temperature every minute and HRC scores hourly for 28 days to compare infection data. Time with abnormal thermal gradients (Model 1) and elevated HRC scores (Model 2) will be compared to the onset of infections. For data analysis, CPtd (abdominal temperature - foot temperature) will be investigated as two derived variables, high CPtd (number/percentage of minutes with CPtd of >2°C) and low CPtd (number/percentage of minutes with CPtd of <0°C). In the infant-level model, the outcome yi will be an indicator of whether the infant was diagnosed with an infection in the first 28 days of life, and the high CPtd and low CPtd variables will be the average over the entire observation period, logit(yi) = β0 + xiβ1 + ziγ. For the day-level model, the outcome yit will be an indicator of whether the ith infant was diagnosed with an infection on the tth day from t = 4 through t = 28 or the day that infection is diagnosed (25 possible repeated measures), logit(yit) = β0 + xitβ1 + zitγ. It will be determined whether a model with only high CPtd or only low CPtd is superior in predicting infection. Also, the correlation of abnormal HRC scores with high CPtd and low CPtd values will be assessed.

DISCUSSION

Study results will inform the design of an interventional study using temperatures and/or heart rate as a predictive tool to alert clinicians of cardiac and autonomic instability present with infection.

Early-life malnutrition causes gastrointestinal dysmotility that is sexually dimorphic

BACKGROUND

Slow gastrointestinal (GI) transit occurs in moderate-to-severe malnutrition. Mechanisms underlying malnutrition-associated dysmotility remain unknown, partially due to lack of animal models. This study sought to characterize GI dysmotility in mouse models of malnutrition.

METHODS

Neonatal mice were malnourished by timed maternal separation. Alternatively, low-protein, low-fat diet was administered to dams, with malnourished neonates tested at two weeks or weaned to the same chow and tested as young adults. We determined total GI transit time by carmine red gavage, colonic motility by rectal bead latency, and both gastric emptying and small bowel motility with fluorescein isothiocyanate-conjugated dextran. We assessed histology with light microscopy, ex vivo contractility and permeability with force-transduction and Ussing chamber studies, and gut microbiota composition by 16S rDNA sequencing.

KEY RESULTS

Both models of neonatal malnutrition and young adult malnourished males but not females exhibited moderate growth faltering, stunting, and grossly abnormal stomachs. Progression of fluorescent dye was impaired in both neonatal models of malnutrition, whereas gastric emptying was delayed only in maternally separated pups and malnourished young adult females. Malnourished young adult males but not females had atrophic GI mucosa, exaggerated intestinal contractile responses, and increased gut barrier permeability. These sex-specific abnormalities were associated with altered gut microbial communities.

CONCLUSIONS & INFERENCES

Multiple models of early-life malnutrition exhibit delayed upper GI transit. Malnutrition affects young adult males more profoundly than females. These models will facilitate future studies to identify mechanisms underlying malnutrition-induced pathophysiology and sex-specific regulatory effects.

Early Doppler Ultrasound in the Superior Mesenteric Artery and the Prediction of Necrotizing Enterocolitis in Preterm Neonates

OBJECTIVES

The purpose of this study was to reveal the correlation between superior mesenteric artery (SMA) blood flow in the first 12 hours of life and the risk of necrotizing enterocolitis (NEC) in preterm neonates.

METHODS

We conducted a prospective study. There were 104 preterm neonates included in our study. The SMA blood flow of each neonate was measured during the first 12 hours of life if the hemodynamic situation was stable. The results of Doppler ultrasound were confidential to the neonatologists and nurses. All of the demographics, comorbidities, and outcomes were recorded and analyzed.

RESULTS

Among all of the demographics and comorbidities, the gestational age was related to the measurements of SMA blood flow. We conducted a single-factor analysis of the occurrence of NEC, including the peak systolic velocity (PSV), end-diastolic velocity, time-averaged mean velocity, differential velocity (DV), resistive index, and pulsatility index. A higher PSV (median [interquartile range], 54.165 [42.423-68.463] versus 42.195 [34.278-48.553] cm/s; P = .027) and DV (median [interquartile range], 47.445 [35.010-60.043] versus 32.565 [27.545-39.073] cm/s; P = .020) were significantly related to the risk of NEC. In the logistic analysis including gestational age, PSV, and DV, NEC was significantly associated with gestational age (odds ratio [95% confidence interval], 0.644 [0.456-0.908]; P = .012) and DV (odds ratio [95% confidence interval], 1.144 [1.058-1.237]; P < .01). The area under the receiver operating characteristic curve for the DV was 0.768, with sensitivity 0.875 and specificity 0.604. The cutoff value of the DV was 34.835 cm/s.

CONCLUSIONS

From this single-center study, we can see the promising value of Doppler ultrasound for the prediction of NEC, but further research is needed.

The effect of early-onset preeclampsia on the intestinal blood flow of preterm infants

BACKGROUND

Preeclampsia is associated with important vascular maternal changes. However, its repercussions on newborns' circulation have hardly been reported.

OBJECTIVE

To investigate whether early-onset preeclampsia is associated with altered blood flow of the superior mesenteric artery (SMA) in preterm infants.

MATERIALS AND METHODS

Prospective study with 60 preterm infants of mothers with early-onset preeclampsia (PE) and 60 of normotensive mothers, paired according to the gestational age, from 2013 to 2016. Maternal, gestational, and neonatal clinical data were evaluated. The outcome of interest was the blood flow velocity in SMA, evaluated by the peak systolic velocity and end-diastolic velocity and by the resistance index and pulsatility index, through the Doppler ultrasound in the first 72 h of life. Covariance analysis was used to determine the PE effect on the SMA blood flow, controlling for possible confounding variables.

RESULTS

The mean gestational age was 30 weeks. Infants of mothers with PE had significantly lower values of peak systolic and end-diastolic velocity (57.75 ± 17.49 and 12.29 ± 5.74) compared with the control group (67.17 ± 29.57 and 15.03 ± 7.52), even after control of covariates.

CONCLUSION

Early-onset preeclampsia is associated with decreased blood flow of SMA in preterm infants on the first days of life.

Abdominal ultrasound should become part of standard care for early diagnosis and management of necrotising enterocolitis: a narrative review

Necrotising enterocolitis (NEC) is a leading cause of death and disability in preterm newborns. Early diagnosis through non-invasive investigations is a crucial strategy that can significantly improve outcomes. Hence, this review gives particular attention to the emerging role of abdominal ultrasound (AUS) in the early diagnosis of NEC, its performance against abdominal radiograph and the benefits of AUS use in daily practice. AUS has been used in the diagnosis and management of NEC for a couple of decades. However, its first-line use has been minimal, despite growing evidence demonstrating AUS can be a critical tool in the early diagnosis and management of NEC. In 2018, the NEC group of the International Neonatal Consortium recommended using AUS to detect pneumatosis and/or portal air in preterm NEC as part of the 'Two out of three' model. To facilitate widespread adoption, and future improvement in practice and outcomes, collaboration between neonatologists, surgeons and radiologists is needed to generate standard operating procedures and indications for use for AUS. The pace and scale of the benefit generated by use of AUS can be amplified through use of computer-aided detection and artificial intelligence.

Role of Abdominal US in Diagnosis of NEC

Current assessment for and diagnosis of necrotizing enterocolitis (NEC) remain inadequate. The introduction of interrogating bowel with ultrasound when NEC is suspected or when NEC has occurred presents greater opportunity to characterize the physical changes that have occurred in the bowel wall structures. The evaluation of bowel by ultrasound has been shown to have high specificity for bowel necrosis. There are current barriers in adoption of these techniques because they have not been integrated into routine diagnostic imaging and are not well incorporated in neonatal medicine.

Negative Temperature Differential in Preterm Infants Less Than 29 Weeks Gestational Age: Associations With Infection and Maternal Smoking

BACKGROUND

Hypothermia is related to increased morbidity and mortality in very preterm infants; continuous temperature monitoring is necessary. Thermoregulation is limited in preterm infants.

OBJECTIVES

The purpose of the research was to assess and describe negative temperature differential (NTD) and assess the associations of NTD with infant demographic characteristics, medical history, and clinical events.

METHODS

An exploratory, case study design was used. Abdominal and foot temperature was measured every minute over the first 2 weeks of life in 22 preterm infants at less than 29 weeks gestational age.

RESULTS

All infants experienced NTD. Daily NTD in all infants across all study days ranged from 0 to 70.7%; 2-week mean NTD over all infants ranged from 7.3% to 38.5%. Four infants treated for late onset of infection had a higher NTD than 18 infants without infection (M = 27.8%, SD = 9.52 vs. M = 16.4%, SD = 5.34, p < .05). Although not statistically significant, higher mean percentage of NTD was noted in infants having early onset infection (24.1% vs. 16.4%), African American race (20.0% vs. 15.3%), and/or being born to a mother who smoked during pregnancy (26.6% vs. 16.7%).

DISCUSSION

A larger study is needed to examine associations between NTD and race, maternal smoking history, and infection. NTD might be used as a biomarker to guide acute clinical care and identify infants at risk for acute and chronic morbidity.

Impact of Continuous vs Bolus Feeding on Splanchnic Perfusion in Very Low Birth Weight Infants: A Randomized Trial

OBJECTIVE

To detect changes in splanchnic perfusion and oxygenation induced by 2 different feeding regimens in infants with intrauterine growth restriction (IUGR) and those without IUGR.

STUDY DESIGN

This was a randomized trial in 40 very low birth weight infants. When an enteral intake of 100 mL/kg/day was achieved, patients with IUGR and those without IUGR were randomized into 2 groups. Group A (n = 20) received a feed by bolus (in 10 minutes), then, after at least 3 hours, received the same amount of formula by continuous nutrition over 3 hours. Group B (n = 20) received a feed administered continuously over 3 hours, followed by a bolus administration (in 10 minutes) of the same amount of formula after at least 3 hours. On the day of randomization, intestinal and cerebral regional oximetry was measured via near-infrared spectroscopy and Doppler ultrasound (US) of the superior mesenteric artery was performed. Examinations were performed before the feed and at 30 minutes after the feed by bolus and before the feed, at 30 minutes after the start of the feed, and at 30 minutes after the end of the feed for the 3-hour continuous feed.

RESULTS

Superior mesenteric artery Doppler US showed significantly higher perfusion values after the bolus feeds than after the continuous feeds. Near-infrared spectroscopy values remained stable before and after feeds. Infants with IUGR and those without IUGR showed the same perfusion and oxygenation patterns.

CONCLUSION

According to our Doppler US results, bolus feeding is more effective than continuous feeding in increasing splanchnic perfusion.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01341236.

Recent Advances of Mucosal Capnometry and the Perspectives of Gastrointestinal Monitoring in the Critically Ill. A Pilot Study

Mucosal capnometry involves the monitoring of partial pressure of carbon dioxide (PCO2) in mucous membranes. Different techniques have been developed and applied for this purpose, including sublingual or buccal sensors, or special gastrointestinal tonometric devices. The primary use of these procedures is to detect compensated shock in critically ill patients or patients undergoing major surgery. Compensatory mechanisms, in the early phases of shock, lead to the redistribution of blood flow towards the vital organs, within ostensibly typical macro-haemodynamic parameters. Unfortunately, this may result in microcirculatory disturbances, which can play a pivotal role in the development of organ failure. In such circumstances mucosal capnometry monitoring, at different gastrointestinal sites, can provide a sensitive method for the early diagnosis of shock. The special PCO2 monitoring methods assess the severity of ischaemia and help to define the necessary therapeutic interventions and testing of these monitors have justified their prognostic value. Gastrointestinal mucosal capnometry monitoring also helps in determining the severity of ischaemia and is a useful adjunctive in the diagnosis of occlusive splanchnic arterial diseases. The supplementary functional information increases the diagnostic accuracy of radiological techniques, assists in creating individualized treatment plans, and helps in follow-up the results of interventions. The results of a pilot study focusing on the interrelation of splanchnic perfusion and gastrointestinal function are given and discussed concerning recent advances in mucosal capnometry.

Doppler flowmetry of the superior mesenteric artery and portal vein: impact for the early prediction of necrotizing enterocolitis in neonates

PURPOSE

Necrotizing enterocolitis (NEC) is a serious gastrointestinal disorder in newborns. Early diagnosis and rapid treatment is essential for seeking good outcome for neonates. The aim of our study was to evaluate intestinal blood flow in superior mesenteric artery (SMA) and portal vein (PV) in neonates with suspected or confirmed NEC and investigate the prognostic cut-off values to develop NEC.

METHODS

Doppler flowmetry of SMA and PV was performed for 62 newborns. Resistive (RI) and pulsatility (PI) indexes were measured in SMA as well as Volumetric blood flow (Vflow) in PV. ROC curves were applied to estimate sensitivity and specificity and to identify cut-off values.

RESULTS

There were 93.5% preterm neonates. 29 patients (46.8%) were diagnosed with NEC and 33 (53.2%) formed a control group. 96.3% NEC patients had RI >0.75 with sensitivity of 96.3% and specificity of 90.9% (OR 260). 88.9% NEC patients had PI >1.85 with sensitivity of 88.9% and specificity of 78.8% (OR 29). Portal Vflow lower than 37 ml/min was present in 89.7% patients with NEC (OR 11.7).

CONCLUSION

Intestinal blood flow Dopplerography can be a useful tool for diagnosing and predicting NEC.

Intestinal blood flow by Doppler ultrasound: the impact of clarithromycin treatment for feeding intolerance in preterm neonates

OBJECTIVE

To compare the blood flow velocities of superior mesenteric artery (SMA) before versus after clarithromycin treatment for feeding intolerance in very low-birth weight infants.

METHODS

A prospective study was conducted in a group of infant <1500 g with feeding intolerance who received clarithromycin 7.5 mg/kg/dose bid. Before and at the third day of the clarithromycin therapy, SMA blood flow velocity was measured with Doppler ultrasound.

RESULTS

SMA peak systolic velocity (PSV) and mean systolic velocity (MV) on the third day of the treatment was found significantly higher than the initial measurement (p = 0.013 and p = 0.027, respectively). End diastolic velocity of the SMA did not change with clarithromycin therapy (p = 0.113). There were no significant changes about pulsatility and resistive index of SMA with regard to clarithromycin therapy.

CONCLUSION

Clarithromycin effects the splanchnic circulation. The rise in PSV and MV in SMA is remarkable. These results suggest that the splanchnic blood flow increases significantly after clarithromycin usage.

Intraventricular hemorrhage as a comorbid factor for intestinal obstruction in very low-birthweight infants

BACKGROUND

In very low-birthweight infants (VLBWI), intestinal obstruction (IO) tends to increase in severity due to the immaturity of the intestine and perinatal events. We examined the clinical comorbid factors related to IO in VLBWI.

METHODS

Clinical data of 160 VLBWI admitted to the neonatal intensive care unit in 2006-2011 were retrospectively reviewed. Patients were divided into two groups: IO group (n = 62) and non-IO group (n = 98). IO was defined as bile excretion via the mouth or nasogastric tube within 30 days after birth. The relationship between clinical factors and the incidence of IO was analyzed.

RESULTS

On univariate analysis, gestational age, birthweight, and the incidence of chronic lung disease, patent ductus arteriosus, intraventricular hemorrhage (IVH), retinopathy of prematurity, and the postnatal use of mechanical ventilation, catecholamines, steroids, and sedatives were associated with IO. On multivariate analysis, only IVH was strongly associated with IO (OR, 4.74; P < 0.01).

CONCLUSIONS

IVH is a significant comorbid factor of IO in VLBWI.

Enteral granulocyte-colony stimulating factor and erythropoietin early in life improves feeding tolerance in preterm infants: a randomized controlled trial

OBJECTIVE

To evaluate the efficacy and safety of enteral recombinant human granulocyte colony-stimulating factor (rhG-CSF) and recombinant human erythropoietin (rhEPO) in preventing feeding intolerance.

STUDY DESIGN

An interventional randomized control trial was conducted in 90 preterm infants born at ≤33 weeks gestational age. The neonates were assigned to 4 groups; 20 received rhG-CSF, 20 received rhEPO, 20 received both, and 30 received distilled water (placebo control). The test solution was given at the beginning of enteral feeding and was discontinued when enteral intake reached 100 mL/kg/day or after a maximum of 7 days, whichever came first. Feeding tolerance and adverse effects of treatment were assessed. Serum granulocyte colony-stimulating factor and erythropoietin levels were measured on days 0 and 7 of treatment.

RESULTS

All neonates tolerated the treatment without side effects. Neonates who received rhG-CSF and/or rhEPO had better feeding tolerance, as reflected by earlier achievement of 75 mL/kg/day, 100 mL/kg/day, and full enteral feeding of 150 mL/kg/day with earlier weight gain and a shorter hospital stay (P < .05). The risk of necrotizing enterocolitis was reduced from 10% to 0% in all treatment groups (P < .05). There was a shorter duration of withholding of feeding secondary to feeding intolerance among neonates receiving both rhG-CSF and rhEPO compared with those receiving placebo (P < .05). Serum levels of granulocyte colony-stimulating factor and erythropoietin at 0 and 7 days did not differ across the treatment groups.

CONCLUSIONS

Enteral administration of rhG-CSF and/or rhEPO improves feeding outcome and decreases the risk of necrotizing enterocolitis in preterm neonates. The mechanism may involve the prevention of villous atrophy.

Very early postnatal changes in splanchnic circulation in term infants

BACKGROUND

Reversed blood flow has been reported in the superior mesenteric artery (SMA) in 92% of healthy term newborns at 2 h of age. By 24 h after birth the end-diastolic velocity became positive in all of the infants.

OBJECTIVE

To characterize hemodynamic changes in the coeliac artery and superior mesenteric artery in healthy term newborns during the first 6 h after birth and to specify the time interval when the negative values of end-diastolic velocity in the superior mesenteric artery become positive.

MATERIALS AND METHODS

Our study included 30 healthy term newborns. The blood flow velocity was assessed by Doppler ultrasonography at 2 h, 4 h and 6 h after birth.

RESULTS

The end-diastolic velocity in the superior mesenteric artery changed from negative values at the age of 2 h (-0.9 cm/s, range -13.2 to 0.0) to positive (7.08 cm/s, range 6.3 to 13.5, P < 0.001) at 6 h after birth. In the coeliac artery, the end-diastolic velocity increased during this period, but negative values were not observed (11.8 cm/s, range 9.3 to 13.9 at 2 h and 18.03 cm/s, range 14.2 to 27.6 at 6 h).

CONCLUSION

Important changes occur in splanchnic circulation during the first 6 h after birth. The rise in end-diastolic velocity in the superior mesenteric artery from negative to positive values in 83% of healthy term newborns is the most important change.

Hemodynamic analysis in infants with late-onset circulatory collapse

BACKGROUND

Late-onset circulatory collapse (LCC) is a disorder in which blood pressure decreases and oliguria suddenly occurs in preterm infants who have survived the acute stage, leading to shock, without contributing underlying factors. In order to evaluate hemodynamic changes during LCC, the correlation between myocardial functions and organ blood flow was investigated with echography.

METHODS

Seven very-low-birthweight infants were given a diagnosis of LCC during the study period. Cardiovascular and organ flow parameters of the infants were recorded prospectively, once a week, and compared with eight control very-low-birthweight infants with matching gestational age. Echographic study was performed before LCC, at the onset of LCC, and after LCC among infants with LCC.

RESULTS

A significant increase in ejection fraction and a significant decrease in end systolic wall stress were observed in infants with the LCC condition. At the same time, the mean blood flow velocity increased significantly in the superior mesenteric artery, while it decreased in the anterior cerebral artery. Systolic blood flow velocity increased and mean velocity was maintained in the renal artery during LCC.

CONCLUSION

LCC is a distributive shock, characterized by a hyperdynamic state and decreased afterload. Echographic examination of organ flow during LCC is useful in understanding the pathophysiology of the disorder.

Correlation of abdominal rSO2 with superior mesenteric artery velocities in preterm infants

OBJECTIVE

Near-infrared spectroscopy (NIRS) is used to monitor brain and kidney perfusion in at-risk premature and term neonates. Although NIRS holds potential for bedside monitoring of intestinal perfusion, there is insufficient evidence showing correlation with mesenteric blood flow. To determine if an association exists between abdominal regional oxygen saturation (A-rSO2) and mesenteric blood flow, we compared changes in A-rSO2 to changes in blood flow velocity in the superior mesenteric artery (SMA) before and after feedings in very-low birthweight infants.

STUDY DESIGN

A-rSO2 was continuously monitored midline below the umbilicus for 3 days in 18 stable 25 to 31 week bolus-fed infants (median BW 1203 g, median age 5 days). We compared change in SMA velocity from immediately before to 10 min and 60 to 120 min after feeding with change in A-rSO2 over the same time. Spearman's rank correlation was used to ascertain if a significant association existed.

RESULT

Change in A-rSO2 was significantly associated with change in systolic, diastolic, and mean SMA velocity from fasting to 60 to 120 min after feeding (P=0.016, 0.021, 0.010) and from 10 min after a feed to 60 to 120 min after feeding (P=0.009, 0.035, 0.032).

CONCLUSION

In very preterm infants, A-rSO2 reflects blood flow in the SMA and can provide non-invasive continuous monitoring of intestinal perfusion. Further studies are indicated to determine the sensitivity of NIRS to detect early intestinal pathology in this population.

Real-time bowel ultrasound to characterize intestinal motility in the preterm neonate

OBJECTIVE

To characterize normal patterns of intestinal motility by ultrasound (US) in the preterm neonate during the first 5 days of life.

STUDY DESIGN

Bowel US examinations were performed with an US machine (Vivid-i, General Electric) equipped with a 13-MHz linear and 7 MHz sector transducer. Still images and clips were taken from all abdominal quadrants along with Doppler of the superior mesenteric artery. Cumulative motility (CM) was quantified for each patient. Comparisons were made between CM for each day of life. Inter-observer correlations were made using the intra-class correlation coefficient. Notation was made of feeding status, bowel sounds and clinical demographics.

RESULT

Twenty infants were enrolled in the study. Seventeen infants had 5 days of complete US results available. Mean CM visualized on day of life (DOL) 1 was 28±12. By DOL 4 (38±17, P=0.006) and DOL 5 (41±20, P=0.008) mean CM increased. There was no difference in the resistance index on days imaged. Mean CM correlated with days to reach full feeds and gestational age, but gestational age was a stronger predictor of days to reach full feeds. Intra-observer correlation coefficient was 0.84.

CONCLUSION

Real-time US provides a quantitative measure of intestinal motility in the preterm infant. Further studies are needed to establish the link between bowel US findings and feeding tolerance.

Feeding tolerance of preterm infants appropriate for gestational age (AGA) as compared to those small for gestational age (SGA)

Preterm infants are often considered too unstable to be fed enterally so they are exposed to complications related to a prolonged enteral fasting. Our study aims to compare feeding tolerance of adequate for gestational age (AGA) versus small for gestational age (SGA) infants and to evaluate which perinatal factors affect feeding tolerance (measured as time to achieve full enteral feeding, FEF). Inborn infants with a gestational age (GA) less than 32 weeks, born from January 2006 to December 2010, were eligible for this study. We enrolled 310 infants. The time to FEF was longer for SGA infants than for AGA, while a longer GA was associated to a reduced time to FEF. A beneficial effect was observed for antenatal steroids, while Apgar score below 7, the administration of inotrops or caffeine, the occurrence of sepsis or NEC and the presence of PDA were associated to a longer time to FEF. When evaluated jointly with a multivariate analysis, GA (p < 0.0001), antenatal steroids prophylaxis (p = 0.002), SGA (p < 0.0001) and occurrence of NEC (p = 0.0002) proved to have independent prognostic impact on the time to FEF. Feeding tolerance is better as GA increases, and worsen in SGA infants. Antenatal betamethasone is effective in reducing the time to FEF in both AGA and SGA.

Transfusion-related necrotizing enterocolitis: a conceptual framework

Necrotizing enterocolitis (NEC) is a disease primarily of prematurity characterized by partial or entire gut necrosis and is associated with significant mortality and morbidity. Recent studies report that approximately 25% to 35% of very low-birth-weight infants less than 1500 g receiving packed red blood cell transfusions develop temporally associated NEC, known as transfusion-related NEC (TR-NEC). Although there are many known risk factors for NEC, this article focuses on 3 contributing factors: packed red blood cell transfusions, enteral feedings, and gastrointestinal immaturity. Previous data suggest that these factors may interact to affect neonatal intestinal tissue oxygenation, which may lead to tissue ischemia, resulting in intestinal injury. This article presents a conceptual framework that combines current theoretical perspectives for TR-NEC, and reviews previous research examining related variables and how their interaction may increase the risk for TR-NEC development. In addition, incorporation of the proposed framework to guide future research and nursing care in this area is discussed.

The role of the intestinal microcirculation in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) continues to be a devastating inflammatory disease of the newborn intestine. Despite advances in management, morbidity and mortality remain high. While it is clear that intestinal ischemia plays a large role in disease pathogenesis, attempts to link NEC to intestinal macrovascular derangement have been largely unsuccessful. More recently, there has been a concerted effort to characterize the pathologic changes of the intestinal microcirculation in response to intestinal injury, including NEC. This microcirculatory regulation is controlled by a balance of vasoconstrictor and vasodilator forces. Vasoconstriction is mediated primarily by endothelin-1 (ET-1), while vasodilation is mediated primarily by nitric oxide (NO). These chemical mediators have been implicated in many aspects of intestinal ischemic injury and NEC, with the balance shifting toward increased vasoconstriction associated with intestinal injury. With a proper understanding of these antagonistic forces, potential therapeutic avenues may result from improving this pathologic microcirculatory dysregulation.

Probiotics supplementation increases intestinal blood flow velocity in extremely low birth weight preterm infants

OBJECTIVE

To determine whether probiotics supplementation affects intestinal blood flow velocity in extremely low birth weight neonates.

STUDY DESIGN

In this randomized, double-blind, placebo-controlled study, probiotics were added to the first enteral feeding and continued until discharge or 34 weeks postmenstrual age. Pulsed Doppler was used to measure preprandial and postprandial (at 30 and 60 min) time-averaged mean velocity (TAMV), peak systolic velocity (PSV) and end diastolic velocity (EDV) during the second week of life after ≥ 7 days of probiotics supplementation.

RESULT

A total of 31 infants were studied, 15 were randomized to the probiotic and 16 to the placebo groups. There was a significant postprandial increase in TAMV for the probiotic vs the placebo group (P=0.035), with PSV and EDV showing a trend. Demographic and clinical variables were similar between the groups.

CONCLUSION

Probiotics administration significantly increases postprandial intestinal blood flow in extremely low birth weight preterm neonates when compared with the placebo group.

Episodes of apnea, desaturation and bradycardia and the development of necrotizing enterocolitis in preterm infants: a case-control study

OBJECTIVE

To investigate for any association between episodes of apnea, desaturation and bradycardia and necrotizing enterocolitis (NEC).

METHODS

Case-control study in infants of gestational age < 30 weeks. For each NEC case we selected two controls. During the period from 2001 to 2007, data were extracted from the nurse's notes of the patient's medical records. A p < 0.05 was statistically significant.

RESULTS

A total of 38 out of 394 infants had NEC (9.6%). There were no significant differences in baseline characteristics between the 2 groups, except for a lower proportion of infants who were receiving breast milk in the NEC group (p = 0.02). There was no difference in the overall number of apneas & bradycardias or severe episodes of desaturation & bradycardia between the 2 groups.

CONCLUSION

No association between episodes of apnea, severe desaturations or bradycardia and development of NEC was observed in this preterm population.

Monitoring technologies in the neonatal intensive care unit: implications for the detection of necrotizing enterocolitis

Necrotizing enterocolitis is the most common and fulminant gastrointestinal disease affecting neonates. Its pathogenesis is heterogeneous and not clearly understood. Early detection could prevent some of the devastating consequences of this disease, but currently there is no noninvasive method of reliable early-stage detection. Here, we review various noninvasive monitoring technologies that have already been employed or show promise for early detection. Each method may have an important role after its technical difficulties are resolved. These are discussed in detail as they relate to various aspects of the putative pathophysiology of this devastating disease.

Gastrointestinal pathology in neonates: new imaging strategies

The mainstay of imaging of gastrointestinal (GI) pathology in infants has always been and still is the plain radiograph of the abdomen and conventional contrast studies. In this review emphasis is placed on the situations where there are new imaging strategies and alternative modalities of imaging, including US, CT, MRI and radionuclide studies. This review will deal with GI pathology in the newborn and in the older neonate. It will also refer to any new approaches to imaging GI pathology in the premature infant. Finally the review will address how antenatal diagnosis of gastrointestinal tract abnormalities has changed the imaging strategy and management of the neonate.

Prediction of feed intolerance and necrotizing enterocolitis in neonates with absent end diastolic flow in umbilical artery and the correlation of feed intolerance with postnatal superior mesenteric artery flow

OBJECTIVES

To evaluate the role of postnatal superior mesenteric artery (SMA) flow in predicting feed intolerance and NEC in the babies who had AEDF in comparison with gestation matched SGA and AGA with normal flow.

DESIGN

This was a prospective cohort study conducted in 62 eligible babies admitted in NICU. Babies were enrolled in 3 groups. Group 1 (n = 23) was SGA and AEDF, group 2 (n = 20) was SGA and group 3 (n = 19) was AGA and both with normal UA flow. In all babies baseline SMA flow was measured before test feed (0.5 ml) and repeated every 15 minutes for 1 hour after the feed.

RESULTS

Feed intolerance was seen in 69.5% of babies in group1 (p = <0.001) as compared to 20% and 17.5% in group 2 and 3. Four (17.3%) babies developed NEC in group1 (p = 0.02) but none in other 2 groups. Baseline peak systolic velocity (PSV) and time average mean velocity (TAMV) at 60 min post feed were significantly (p = 0.01 and 0.028 respectively) lower in group1 than group3. TAMV and PSV at 60 min post feed were significantly lower (p = 0.028 and 0.03) in babies with feed intolerance as compared to no feed intolerance group. Absent end diastolic flow and hypoglycemia were independent risk factors for feed intolerance.

CONCLUSION

SGA babies with AEDF had higher incidence of feed intolerance and NEC. Serial SMA flow studies specially the 60 min post feed study may help in differentiating which babies are likely to develop feed intolerance.

Small intestinal disorders in the elderly

The topic of gastroenterology (GI) in the elderly has been extensively reviewed. It takes special skill, patience and insight to interview the elderly, as well as to appreciate their altered physiology and interpretation of their presenting symptoms and signs, often against an extreme background of complex medical problems. The maldigestion and malabsorption coupled with altered motility contributes to the development of malnutrition. There generally a decrease of function of the GI tract, but there may be loss of adaptability in response to changes in diet or nutritional stress. Pathological alterations which might lead to minor overall intestinal functional variations in the young because of a normal process of adaptation, may lead to much more serious events in the elderly.

Aetiology and pathogenesis of IUGR

Intrauterine growth restriction (IUGR) is a major cause of perinatal mortality and morbidity. A complex and dynamic interaction of maternal, placental and fetal environment is involved in ensuring normal fetal growth. An imbalance or lack of coordination in this complex system may lead to IUGR. Animal studies have given us an insight into some aspects of the basic pathophysiology of IUGR, and recent technologies such as Doppler studies of maternal and fetal vessels have added further information. The aetiologies of IUGR are diverse, involving multiple complex mechanisms, which make understanding of the pathophysiology difficult. However, particular focus is placed on the mechanisms involved in uteroplacental insufficiency as a cause of IUGR, as (1) it is common, (2) outcome can be good if timing of delivery is optimal and (3) it may be amenable to therapy in the future. While the research into the pathophysiology of IUGR continues, there have been interesting discoveries related to the genetic contribution to IUGR and the intrauterine programming of adult-onset diseases attributed to IUGR.

Early nasal continuous positive airway pressure and necrotizing enterocolitis in preterm infants

BACKGROUND

The use of early nasal continuous positive airway pressure (ENCPAP) as the mode of initial respiratory support for very low birth weight (VLBW) infants has been increasing. The impact of CPAP and oxygen on gut mucosa and perfusion in premature infants is not known. The relation between ENCPAP and necrotizing enterocolitis (NEC) has not been adequately addressed.

OBJECTIVE

To evaluate if the use of an individualized respiratory management strategy encouraging the use of ENCPAP is associated with an increased risk of NEC, and to determine risk factors for NEC in premature infants supported by CPAP.

METHODS

A retrospective analysis was conducted on VLBW infants (birth weight < 1500 g) managed at 2 institutions that use an ENCPAP respiratory management strategy for premature infants. Data on the use of oxygen and mode of ventilatory support were collected during the first 3 days of life. Diagnosis of NEC was used as the dependent variable in a logistic regression model. Birth weight, gender, prenatal steroid use, mode of respiratory support (CPAP versus ventilator) and fraction of inspired oxygen, umbilical artery catheter placement, partial pressure of oxygen, patent ductus arteriosus, early sepsis, hospital, and delivery room management (ENCPAP versus initial intubation) were controlled for in the model.

RESULTS

Data on 343 premature infants were collected for this study. Mean birth weight was 999 +/- 289 g and gestational age was 28 +/- 2.6 weeks. The majority of patients were managed with ENCPAP, with only 13% of patients intubated in the delivery room. The overall incidence of NEC was 7% (n = 24). The exposure to ENCPAP did not increase the risk for NEC compared with the use of a ventilator. CONCLUSIONS. The risk of NEC in VLBW premature infants was not increased by the use of ENCPAP. Initial respiratory support with ENCPAP seems to be a safe alternative to routine intubation and mechanical ventilation in premature infants.

Peculiaridades da circulação mesentérica em recém-nascidos e suas implicações em doenças gastrintestinais do período neonatal

OBJETIVO:Descrever peculiaridades da circulação mesentérica neonatal e caracterizar fatores de suscetibilidade ao desenvolvimento de doenças gastrintestinais e alterações do fluxo sanguíneo da artéria mesentérica superior por meio da dopplerfluxometria. FONTES DE DADOS: Livros-textos e publicações indexadas no Medline e SciELO nos últimos 20 anos, utilizando-se as palavras chaves: "mesenteric artery", "superior mesenteric artery", "newborn intestinal circulation", "necrotizing enterocolitis", "doppler flow velocimetry". SÍNTESE DOS DADOS: Alterações do fluxo sanguíneo mesentérico são um dos fatores predisponentes da enterocolite necrosante, doença neonatal de alta morbimortalidade que acomete principalmente prematuros. A circulação mesentérica é peculiar no período neonatal tanto em relação ao seu estado basal, quanto à sua resposta frente a estímulos fisiológicos. Variações da irrigação mesentérica podem ser inerentes à própria fase de desenvolvimento vascular intestinal do recém-nascido pré-termo, com possíveis agravos de fatores perinatais como: insuficiência placentária, asfixia, infecção, cateterismo umbilical, drogas (indometacina e cafeína), fototerapia, alimentação artificial e progressão rápida da dieta. A dopplerfluxometria permite o estudo da irrigação de órgãos-alvo e pode quantificar o fluxo sanguíneo, a resistência vascular e predizer situações de risco para doenças do trato gastrintestinal no período neonatal. CONCLUSÕES: O recém-nascido apresenta peculiaridades de irrigação sanguínea gastrintestinal. A dopplerfluxometria da artéria mesentérica superior é um método não invasivo que determina as condições circulatórias no território intestinal.

Neonatal colour Doppler ultrasound study: normal values of abdominal blood flow velocities in the neonate during the first month of life

BACKGROUND

Doppler US to measure abdominal blood flow velocities (ABFV) is increasingly used to investigate intestinal haemodynamics in several clinical conditions in neonates. Studies that provide reference values of ABFV during the entire neonatal period are currently lacking.

OBJECTIVE

To make available normal reference values of ABFV and Doppler indices in the coeliac trunk and superior mesenteric artery during the first month of life in term and healthy preterm infants.

MATERIALS AND METHODS

ABFV were obtained with colour Doppler US in 69 neonates (12 term, 57 preterm) divided into four gestational age groups (25-28 weeks, 29-32 weeks, 33-36 weeks, and 37-41 weeks).

RESULTS

ABFV increased with increasing gestational and postnatal age. We also provide normal reference values of ABFV and Doppler indices to compare with measurements of abdominal blood flow changes during the neonatal period for diagnostic, therapeutic and prognostic purposes.

CONCLUSION

These longitudinal reference values provide a useful tool for assessing possible alteration in ABFV secondary to neonatal pathologies.

Doppler sonography of the superior mesenteric artery in children with recurrent abdominal pain

PURPOSE

Abdominal pain is one of the most common conditions in childhood and adolescence. The aim of this study was to evaluate the superior mesenteric artery (SMA) Doppler findings in children with recurrent abdominal pain.

METHOD

Duplex Doppler sonographic measurements were performed in 20 patients with recurrent abdominal pain and in 34 controls.

RESULTS

The mean blood flow velocities, blood flow volume, and diameter of the SMA were significantly lower in patients with recurrent abdominal pain than in controls.

CONCLUSION

Insufficient development and/or vasoconstriction of the SMA vascular bed may be involved in recurrent abdominal pain, but further studies on larger groups are needed to test this hypothesis.

Predictors of necrotizing enterocolitis in preterm growth-restricted neonates

OBJECTIVE

The purpose of this study was to test the hypothesis that multivessel fetal Doppler imaging provides enhanced prediction of necrotizing enterocolitis (NEC) in preterm placental insufficiency.

STUDY DESIGN

Placental-based growth-restricted fetuses (abdominal circumference <5%, abnormal umbilical artery [UA] Doppler imaging) were examined. UA, middle cerebral artery, ductus venosus, and umbilical vein (UV) were evaluated prenatally and were assessed for their ability to predict NEC in neonates who were delivered at <37 weeks of gestation.

RESULTS

Thirty-nine of 404 neonates (9.7%) experienced NEC. Among these, the mortality rate was 15.4% (6/39 neonates; odds ratio, 2.7; 95% CI, 1.03-7.11). NEC cases had higher UA Doppler indices prenatally (P = .023), lower gestational ages and birthweight at delivery (P < .0001, respectively), 5-minute Apgar scores of <7, and higher umbilical cord artery base deficit (P < .01, respectively). NEC was more likely after prenatal UV pulsations (odds ratio, 2.4; 95% CI, 1.13-5.14; P = .028) and severe cardiovascular abnormality (composite variable incorporating UA- absent or reversed end diastolic velocity, absent or reversed ductus venosus a-wave, or UV pulsations; odds ratio, 2.1; 95% CI, 1.06-4.05; P = .029) Logistic regression revealed birthweight and base deficit as the main contributors of NEC (r(2) = 0.20; P < .0001). Receiver operating characteristic analyses revealed birthweight of <790 g (sensitivity, 74.4%; specificity, 72.9%; P < .0001) and gestational age of < or =32.2 weeks (sensitivity, 94.9%; specificity, 45.8%; P < .0001) as optimal cut-offs that provide an odds ratio for NEC of 8.2 (95% CI, 3.9-17.6; P < .0001).

CONCLUSION

Placental disease predisposes the severely growth-restricted neonate to necrotizing enterocolitis. Even when arterial and venous Doppler variables are taken into consideration, birthweight remains the predominant risk factor for NEC. Further research should focus on the critical transition to neonatal life to identify relevant triggers in predisposed neonates.

The neonatal intestinal vasculature: contributing factors to necrotizing enterocolitis

Based on the demonstration of coagulation necrosis, it is clear that intestinal ischemia plays a role in the pathogenesis of necrotizing enterocolitis (NEC). Intestinal vascular resistance is determined by a dynamic balance between vasoconstrictive and vasodilatory inputs. In the newborn, this balance heavily favors vasodilation secondary to the copious production of endothelium-derived nitric oxide (NO), a circumstance which serves to ensure adequate blood flow and thus oxygen delivery to the rapidly growing intestine. Endothelial cell injury could shift this balance in favor of endothelin (ET)-1-mediated vasoconstriction, leading to intestinal ischemia and tissue injury. Evidence obtained from animal models and from human tissue collected from infants with NEC implicates NO and ET-1 dysregulation in the pathogenesis of NEC. Strategies focused on maintaining the delicate balance favoring vasodilation in the newborn intestinal circulation may prove to be useful in the prevention and treatment of NEC.

Nasal continuous positive airway pressure affects pre- and postprandial intestinal blood flow velocity in preterm infants

OBJECTIVE

To measure the effect of nasal continuous positive airway pressure (CPAP) on intestinal blood flow velocity responses to enteral feedings and left ventricular output (LVO).

STUDY DESIGN

Eighteen infants completed the study (birth weight 1793+/-350 g, gestational age 32.1+/-1.1 weeks). On the day infants were weaned from CPAP to room air, pre- and postprandial (0, 30, 60 and 90 min after feeding) mean velocity (MV), peak systolic velocity (PSV) and end diastolic velocity (EDV) were measured for one feeding given when receiving CPAP ('on CPAP'), and for one feeding given after CPAP had been discontinued ('off CPAP'). Preprandial LVO was measured before and after CPAP discontinuation.

RESULT

MV and PSV were significantly lower when infants were on CPAP (P<0.05). Maximum postprandial MV, PSV and EDV occurred at 30 min when on CPAP and at 60 min when off CPAP. Preprandial LVO was similar when infants were on and off CPAP.

CONCLUSION

CPAP administration affects pre- and postprandial intestinal blood flow velocity, which may impact tolerance to enteral feedings.

Cardiovascular impact of dobutamine in neonates with myocardial dysfunction

OBJECTIVE

To study effects of dobutamine on cardiac functional parameters, cerebral, mesenteric and renal blood flow in preterm neonates with myocardial dysfunction.

STUDY DESIGN

Prospective evaluation of Doppler sonographically measured left ventricular systolic time intervals, stroke volume (SV), cardiac output (CO), and blood flow parameters of anterior cerebral artery (ACA), superior mesenteric artery (SMA) and renal arteries (RA), before, after 20 min and 8-10 h of dobutamine treatment in 20 neonates (gestational age 29.6+/-4.4 weeks, birth weight 1450+/-609 g and postnatal age 2+/-2.1 days). Dobutamine was given in a mean dosage of 9.1+/-1.1 microg/kg.

RESULTS

After 20 min SV increased from 1.71+/-0.5 ml to 2.12+0.57 ml/kg, CO from 223+/-76 to 290 ml/kg/min. A shortening of left ventricular pre ejection period from 86+/-12 to 66+/-13 ms and of the ratio of pre-ejection period/ejection time from 0.52+/-0.12 to 0.40+/-0.11 were observed. Blood flow velocities of ACA increased after 8-10 h: peak systolic flow velocity (PSV) from 19.0+/-6 to 29.6+/-7.1 ms, end diastolic velocity (EDV) from 2.9+/-2.6 to 12.7+/-11.3 ms. PSV of SMA increased from 32.5+/-4.7 to 49.7+/-7.8 ms after 8-10 h, EDV from 8.9+/-8 ms to 20.6+/-6.1 ms. PSV of RA increased from 18.2+/-6.1 ms to 39.9+/-4.8 ms, EDV from 2.2+/-1.2 to 8.2+/-2.1 ms after 8-10 h. The pulsatility indices decreased significantly after 8-10 h: ACA from 2.3+/-0.6 to 1.4+/-0.5, SMA from 1.7 to 1.2 and RA from 2.57 to 1.57.

CONCLUSION

Dobutamine improves the cardiac functional parameters already after 20 min and has an influence on the blood flow parameters of ACA, SMA and RA 8-10 h after administration in neonates with myocardial dysfunction.