Estimating Preterm Lung Volume: A Comparison of Lung Ultrasound, Chest Radiography, and Oxygenation.

OBJECTIVE: To determine the relationship between lung ultrasound (LUS) examination, chest radiograph (CXR), and radiographic and clinical evaluations in the assessment of lung volume in preterm infants. STUDY DESIGN: In this prospective cohort study LUS was performed before CXR on 70 preterm infants and graded using (1) a LUS score, (2) an atelectasis score, and (3) measurement of atelectasis depth. Radiographic diaphragm position and radio-opacification were used to determine global and regional radiographic atelectasis. The relationship between LUS, CXR, and oxygenation was assessed using receiver operator characteristic and correlation analysis. RESULTS: LUS scores, atelectasis scores, and atelectasis depth did not correspond with radiographic global atelectasis (area under receiver operator characteristics curves, 0.54 [95% CI, 0.36-0.71], 0.49 [95% CI, 0.34-0.64], and 0.47 [95% CI, 0.31-0.64], respectively). Radiographic atelectasis of the right upper, right lower, left upper, and left lower quadrants was predicted by LUS scores (0.75 [95% CI, 0.59-0.92], 0.75 [95% CI, 0.62-0.89], 0.69 [95% CI, 0.56-0.82], and 0.63 [95% CI, 0.508-0.751]) and atelectasis depth (0.66 [95% CI, 0.54-0.78], 0.65 [95% CI, 0.53-0.77], 0.63 [95% CI, 0.50-0.76], and 0.56 [95% CI, 0.44-0.70]). LUS findings were moderately correlated with oxygen saturation index (ρ = 0.52 [95% CI, 0.30-0.70]) and saturation to fraction of inspired oxygen ratio (ρ = -0.63 [95% CI, -0.76 to -0.46]). The correlation between radiographic diaphragm position, the oxygenation saturation index, and peripheral oxygen saturation to fraction of inspired oxygen ratio was very weak (ρ = 0.36 [95% CI, 0.11-0.59] and ρ = -0.32 [95% CI, -0.53 to -0.07], respectively). CONCLUSIONS: LUS assessment of lung volume does not correspond with radiographic diaphragm position preterm infants. However, LUS predicted radiographic regional atelectasis and correlated with oxygenation. The relationship between radiographic diaphragm position and oxygenation was very weak. Although LUS may not replace all radiographic measures of lung volume, LUS more accurately reflects respiratory status in preterm infants. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12621001119886.

Quantitative lung ultrasound detects dynamic changes in lung recruitment in the preterm lamb.

BACKGROUND: Lung ultrasound (LUS) may not detect small, dynamic changes in lung volume. Mean greyscale measurement using computer-assisted image analysis (Q-LUSMGV) may improve the precision of these measurements. METHODS: Preterm lambs (n = 40) underwent LUS of the dependent or non-dependent lung during static pressure-volume curve mapping. Total and regional lung volumes were determined using the super-syringe technique and electrical impedance tomography. Q-LUSMGV and gold standard measurements of lung volume were compared in 520 images. RESULTS: Dependent Q-LUSMGV moderately correlated with total lung volume (rho = 0.60, 95% CI 0.51-0.67) and fairly with right whole (rho = 0.39, 0.27-0.49), central (rho = 0.38, 0.27-0.48), ventral (rho = 0.41, 0.31-0.51) and dorsal regional lung volumes (rho = 0.32, 0.21-0.43). Non-dependent Q-LUSMGV moderately correlated with total lung volume (rho = 0.57, 0.48-0.65) and fairly with right whole (rho = 0.43, 0.32-0.52), central (rho = 0.46, 0.35-0.55), ventral (rho = 0.36, 0.25-0.47) and dorsal lung volumes (rho = 0.36, 0.25-0.47). All correlation coefficients were statistically significant. Distinct inflation and deflation limbs, and sonographic pulmonary hysteresis occurred in 95% of lambs. The greatest changes in Q-LUSMGV occurred at the opening and closing pressures. CONCLUSION: Q-LUSMGV detected changes in total and regional lung volume and offers objective quantification of LUS images, and may improve bedside discrimination of real-time changes in lung volume. IMPACT: Lung ultrasound (LUS) offers continuous, radiation-free imaging that may play a role in assessing lung recruitment but may not detect small changes in lung volume. Mean greyscale image analysis using computer-assisted quantitative LUS (Q-LUSMGV) moderately correlated with changes in total and regional lung volume. Q-LUSMGV identified opening and closing pressure and pulmonary hysteresis in 95% of lambs. Computer-assisted image analysis may enhance LUS estimation of lung recruitment at the bedside. Future research should focus on improving precision prior to clinical translation.

Application of Neonatologist Performed Echocardiography in the Assessment and Management of Neonatal Heart Failure unrelated to Congenital Heart Disease.

Neonatal heart failure (HF) is a progressive disease caused by cardiovascular and non-cardiovascular abnormalities. The most common cause of neonatal HF is structural congenital heart disease, while neonatal cardiomyopathy represents the most common cause of HF in infants with a structurally normal heart. Neonatal cardiomyopathy is a group of diseases manifesting with various morphological and functional phenotypes that affect the heart muscle and alter cardiac performance at, or soon after birth. The clinical presentation of neonates with cardiomyopathy is varied, as are the possible causes of the condition and the severity of disease presentation. Echocardiography is the selected method of choice for diagnostic evaluation, follow-up and analysis of treatment results for cardiomyopathies in neonates. Advances in neonatal echocardiography now permit a more comprehensive assessment of cardiac performance that could not be previously achieved with conventional imaging. In this review, we discuss the current and emerging echocardiographic techniques that aid in the correct diagnostic and pathophysiological assessment of some of the most common etiologies of HF that occur in neonates with a structurally normal heart and acquired cardiomyopathy and we provide recommendations for using these techniques to optimize the management of neonate with HF.

Education, training, and accreditation of Neonatologist Performed Echocardiography in Europe-framework for practice.

There is a growing interest worldwide in using echocardiography in the neonatal unit to act as a complement to the clinical assessment of the hemodynamic status of premature and term infants. However, there is a wide variation in how this tool is implemented across many jurisdictions, the level of expertise, including the oversight of this practice. Over the last 5 years, three major expert consensus statements have been published to provide guidance to neonatologists performing echocardiography, with all recommending a structured training program and clinical governance system for quality assurance. Neonatal practice in Europe is very heterogeneous and the proximity of neonatal units to pediatric cardiology centers varies significantly. Currently, there is no overarching governance structure for training and accreditation in Europe. In this paper, we provide a brief description of the current training recommendations across several jurisdictions including Europe, North America, and Australia and describe the steps required to achieve a sustainable governance structure with the responsibility to provide accreditation to neonatologist performed echocardiography in Europe.

Inflammation, lipids and aortic intima-media thickness in newborns following chorioamnionitis.

AIM: This study investigated whether chorioamnionitis was associated with increased inflammation, dyslipidaemia and adverse cardiovascular phenotypes in the immediate postnatal period. METHODS: This prospective case-control study included preterm infants (30(+0) -35(+6) weeks gestational age, GA) whose mothers did not have pregnancy-related conditions that may influence outcomes. Chorioamnionitis was diagnosed by placental histology, and infants were divided retrospectively into cases (chorioamnionitis-exposed) and controls (unexposed). Serum high-sensitivity C-reactive protein (hsCRP), lipid profile, far-wall abdominal aortic intima-media thickness (aIMT) and blood pressure (BP) were measured in the first week of life. RESULTS: There were 20 (16 male, mean GA 32.4 weeks) cases and 31 (12 male, mean GA 32.6 weeks) controls. Histological chorioamnionitis was associated with a significant increase in hsCRP and a non-significant trend towards an adverse lipid profile. There was no evidence of differences in aIMT or BP. CONCLUSION: Preterm infants exposed to chorioamnionitis have greater postnatal inflammation. There were no early postnatal differences in aIMT or BP. The inflammatory stimulus of chorioamnionitis late in gestation may be of insufficient intensity and duration to result in immediate postnatal alterations to arterial structure. Cardiovascular follow-up of infants exposed to chorioamnionitis may identify differential risk trajectories and subsequent inflammatory responses.

Fulminant liver failure in a neonate.

Neonatal acute liver disease is relatively rare, with multiple different aetiologies including congenital infections, metabolic disorders, gestational alloimmune liver disease, haemophagocytic lymphohistiocytosis, and ischaemic injury. We report a case of neonatal liver failure in a preterm, growth-restricted infant, who underwent extensive investigation and was clinically diagnosed with gestational alloimmune liver disease, which was confirmed on post-mortem examination. We then discuss management of neonatal liver failure and gestational alloimmune liver disease, including maternal management in future pregnancies.

Hemodynamic effects of nasal continuous positive airway pressure in preterm infants with evolving chronic lung disease, a crossover randomized trial.

Previous studies suggest that high airway pressure may compromise cardiac output. We investigated the effect of 3 nasal continuous positive airway pressure levels on cardiac output in preterm infants with evolving chronic lung disease. We found that brief changes in continuous positive airway pressure did not affect cardiac output.

The effects of nasal continuous positive airway pressure on cardiac function in premature infants with minimal lung disease: a crossover randomized trial.

OBJECTIVE: To assess the effects of different nasal continuous positive airway pressure (nCPAP) pressures on cardiac performance in preterm infants with minimal lung disease, we conducted a randomized, blinded crossover study. STUDY DESIGN: We studied infants between 28 and 34 weeks' corrected gestational age, treated with nCPAP of 5 cm H2O, in air. Infants with significant cardiac shunts were excluded. Infants were randomly assigned to nCPAP levels of 4, 6, and 8 cm H2O for 15 minutes each. Right and left ventricular outputs and left pulmonary artery and superior vena cava flows were measured 15 minutes after each change. RESULTS: Thirty-four infants born at a mean gestational age of 29 weeks with a birth weight of 1.3 kg were studied. There were no significant differences in right and left ventricular outputs and left pulmonary artery and superior vena cava flows at different levels of nCPAP. CONCLUSION: We investigated the effect of increasing nCPAP levels on cardiac output. We conclude that nCPAP levels between 4 and 8 cm H2O did not have an effect on cardiac output in stable preterm infants with minimal lung disease.

A case of ultrasound-guided prenatal diagnosis of prune belly syndrome in Papua New Guinea--implications for management.

BACKGROUND: Prune belly syndrome is a rare congenital malformation of unknown aetiology and is characterised by abnormalities of the urinary tract, a deficiency of abdominal musculature and bilateral cryptorchidism in males. We report a case of prune belly syndrome from Papua New Guinea, which was suspected on pregnancy ultrasound scan and confirmed upon delivery. CASE PRESENTATION: A 26-year-old married woman, Gravida 3 Para 2, presented to antenatal clinic in Madang, Papua New Guinea, at 21(+5) weeks' gestation by dates. She was well with no past medical or family history of note. She gave consent to participate in a clinical trial on prevention of malaria in pregnancy and underwent repeated ultrasound examinations which revealed a live fetus with persistent megacystis and anhydramnios. Both mother and clinicians agreed on conservative management of the congenital abnormality. The mother spontaneously delivered a male fetus weighing 2010 grams at 34 weeks' gestation with grossly abnormal genitalia including cryptorchidism, penile aplasia and an absent urethral meatus, absent abdominal muscles and hypoplastic lungs. The infant passed away two hours after delivery. This report discusses the implications of prenatal detection of severe congenital abnormalities in PNG. CONCLUSION: This first, formally reported, case of prune belly syndrome from a resource-limited setting in the Oceania region highlights the importance of identifying and documenting congenital abnormalities. Women undergoing antenatal ultrasound examinations must be carefully counseled on the purpose and the limitations of the scan. The increasing use of obstetric ultrasound in PNG will inevitably result in a rise in prenatal detection of congenital abnormalities. This will need to be met with adequate training, referral mechanisms and better knowledge of women's attitudes and beliefs on birth defects and ultrasound. National medicolegal guidance regarding induced abortion and resuscitation of a fetus with severe congenital abnormalities may be required.

Relationships between early postnatal cranial ultrasonography linear measures and neurodevelopment at 2 years in infants born at <30 weeks' gestational age without major brain injury.

OBJECTIVE: To explore relationships of early postnatal cranial ultrasonography (cUS) linear measures of brain size and brain growth with neurodevelopment at 2 years in infants born <30 weeks' gestational age (GA) and free of major brain injury. DESIGN: Prospective observational cohort study. SETTING: Tertiary neonatal intensive care unit. PATIENTS: 139 infants born <30 weeks' GA, free of major brain injury on neonatal cUS and without congenital or chromosomal anomalies known to affect neurodevelopment. INTERVENTION: Linear measures of brain tissue and fluid spaces made from cUS at 1-week, 1-month and 2-months' postnatal age. MAIN OUTCOME MEASURES: Cognitive, language and motor scores on the Bayley Scales of Infant and Toddler Development, third edition at 2 years' corrected age. RESULTS: 313 scans were evaluated from the 131 children who were assessed at 2 years. Larger measures of the corpus callosum at 1 week, 1 month and 2 months, cerebellum and vermis at 2 months and faster positive growth of the cerebellum and vermis between 1 month and 2 months, were related to higher cognitive and language scores at 2 years. No relation between tissue measures and motor scores was found. Larger measures, and faster rate of increase, of fluid spaces within the first weeks after birth were related to better cognitive, language and motor outcomes at 2 years. CONCLUSIONS: Early postnatal cUS linear measures of brain tissue were related to cognitive and language development at 2 years in infants born <30 weeks' GA without major brain injury. Relationships between cUS linear measures of fluid spaces in the early postnatal period and later neurodevelopment warrant further exploration.

Lung ultrasound of the dependent lung detects real-time changes in lung volume in the preterm lamb.

BACKGROUND: Effective lung protective ventilation requires reliable, real-time estimation of lung volume at the bedside. Neonatal clinicians lack a readily available imaging tool for this purpose. OBJECTIVE: To determine the ability of lung ultrasound (LUS) of the dependent region to detect real-time changes in lung volume, identify opening and closing pressures of the lung, and detect pulmonary hysteresis. METHODS: LUS was performed on preterm lambs (n=20) during in vivo mapping of the pressure-volume relationship of the respiratory system using the super-syringe method. Electrical impedance tomography was used to derive regional lung volumes. Images were blindly graded using an expanded scoring system. The scores were compared with total and regional lung volumes, and differences in LUS scores between pressure increments were calculated. RESULTS: Changes in LUS scores correlated moderately with changes in total lung volume (r=0.56, 95% CI 0.47-0.64, p<0.0001) and fairly with right whole (r=0.41, CI 0.30-0.51, p<0.0001), ventral (r=0.39, CI 0.28-0.49, p<0.0001), central (r=0.41, CI 0.31-0.52, p<0.0001) and dorsal (r=0.38, CI 0.27-0.49, p<0.0001) regional lung volumes. The pressure-volume relationship of the lung exhibited hysteresis in all lambs. LUS was able to detect hysteresis in 17 (85%) lambs. The greatest changes in LUS scores occurred at the opening and closing pressures. CONCLUSION: LUS was able to detect large changes in total and regional lung volume in real time and correctly identified opening and closing pressures but lacked the precision to detect small changes in lung volume. Further work is needed to improve precision prior to translation to clinical practice.

Relationships between early postnatal cranial ultrasonography linear measures and neurobehaviour at term-equivalent age in infants born <30 weeks' gestational age.

BACKGROUND: The relationship between early postnatal brain development and neurobehaviour at term-equivalent age (TEA) remains uncertain. AIM: We aimed to explore relationships between early postnatal cranial ultrasonography (cUS) linear measures of brain size and brain growth with neurobehaviour at TEA in infants born <30 weeks' gestational age (GA). STUDY DESIGN: Prospective observational cohort study. SUBJECTS: 137 infants born <30 weeks' GA without major brain injury on neonatal cUS. OUTCOME MEASURES: Neurobehaviour at TEA assessed using the General Movements Assessment (GMA) and Hammersmith Neonatal Neurological Examination (HNNE). RESULTS: The GMA was administered in 115/137 (84%) infants; 80 (70%) presented with abnormal general movements (GMs) (79 poor repertoire, 1 cramped synchronised). The HNNE was assessed in 106/137 (77%) infants; 52 (49%) had a suboptimal total score. With respect to brain size, larger measures of the corpus callosum length (CCL) and right anterior horn width (AHW) at 1-month were related to lower risk of abnormal GMs, and larger measures of the biparietal diameter at 1-week and 2-months were related to lower risk of a suboptimal HNNE. As for brain growth, increases of the CCL and transcerebellar diameter between birth and 1-month, and left and right AHWs between 1- and 2-months, were related to lower risk of abnormal GMs. CONCLUSION: Early postnatal brain size and brain growth were related to neurobehaviour at TEA in infants born <30 weeks' GA. This study provides preliminary evidence for the prognostic utility of early postnatal cUS linear measures as potential markers of neurodevelopment in later childhood.

Lung ultrasound during newborn resuscitation predicts the need for surfactant therapy in very- and extremely preterm infants.

INTRODUCTION: Early identification of infants requiring surfactant therapy improves outcomes. We evaluated the accuracy of delivery room lung ultrasound (LUS) to predict surfactant therapy in very- and extremely preterm infants. METHODS: Infants born at <320/7 weeks were prospectively enrolled at 2 centres. LUS videos of both sides of the chest were obtained 5-10 min, 11-20 min, and 1-3 h after birth. Clinicians were masked to the results of the LUS assessment and surfactant therapy was provided according to local guidelines. LUS videos were graded blinded to clinical data. Presence of unilateral type 1 ('whiteout') LUS or worse was considered test positive. Receiver Operating Characteristic (ROC) analysis compared the accuracy of LUS and an FiO2 threshold of 0.3 to predict subsequent surfactant therapy. RESULTS: Fifty-two infants with a median age of 276/7 weeks (IQR 260/7-286/7) were studied. Thirty infants (58%) received surfactant. Area under the ROC curve (AUC) for LUS at 5-10 min, 11-20 min and 1-3 h was 0.78 (95% CI, 0.66-0.90), 0.76 (95% CI, 0.65-0.88) and 0.86 (95% CI, 0.75-0.97) respectively, outperforming FiO2 at the 5-10 min timepoint (AUC 0.45, 95% CI 0.29-0.62, p = 0.001). At 11-20 min, LUS had a specificity of 95% (95% CI 77-100%) and sensitivity of 59% (95% CI, 39-77%) to predict surfactant therapy. All infants born at 23-276/7 weeks with LUS test positive received surfactant. Twenty-six infants (50%) had worsening of LUS grades on serial assessment. CONCLUSIONS: LUS in the delivery room and accurately predicts surfactant therapy in infants <320/7 weeks.

Neonatologist performed point-of-care bowel ultrasound: Is the time right?

INTRODUCTION: This review acquaints neonatal clinicians using point-of-care ultrasound with a range of pathological bowel ultrasound findings, with the aim to promote utility of this skill as a diagnostic assessment tool in diseased neonatal intestinal states. OVERVIEW: A range of normal and pathological bowel ultrasound findings are illustrated with case examples from our neonatal intensive care unit. The technical challenges of lack of familiarity with sonographic appearance of bowel (healthy and diseased), occurrence of gas artefacts and requirements of high-resolution linear transducer probes are described to allow the development of skills amongst neonatologists trained in point-of-care ultrasound. Plain abdominal radiography continues to remain the standard investigation to differentiate benign bowel states such as continuous positive airway pressure (CPAP) belly syndrome in preterm infants from life-threatening pathological intestinal states such as necrotising enterocolitis. Although plain radiography is the gold standard modality in the evaluation of neonatal diseased bowel states, real-time point-of-care bowel ultrasound performed in conjunction can provide valuable information on bowel peristalsis, bowel wall thickness and bowel vascularity. Abnormal configuration of superior mesenteric vessels on colour Doppler can alert the clinician to the diagnosis of neonatal intestinal malrotation-a time critical emergency. CONCLUSION: Further research is needed to explore true-negative and true-positive predictive values of bowel ultrasound. However, with expansion of knowledge, appropriate training of techniques, neonatologists will be able to enhance their diagnostic acumen by performing point-of-care bowel ultrasound in conjunction with plain radiography in the evaluation of broad array of neonatal intestinal states.

Lung ultrasound immediately after birth to describe normal neonatal transition: an observational study.

OBJECTIVE: Lung ultrasound (LUS) has shown promise as a diagnostic tool for the evaluation of the newborn with respiratory distress. No study has described LUS during 'normal' transition. Our goal was to characterise the appearance of serial LUS in healthy newborns from the first minutes after birth until airway liquid clearance is achieved. STUDY DESIGN: Prospective observational study. SETTING: Single-centre tertiary perinatal centre in Australia. PATIENTS: Of 115 infants born at ≥35 weeks gestational age, mean (SD) gestational age of 386/7 weeks±11 days, mean birth weight of 3380±555 g, 51 were delivered vaginally, 14 via caesarean section (CS) after labour and 50 infants via elective CS. INTERVENTIONS: We obtained serial LUS videos via the right and left axillae at 1-10 min, 11-20 min and 1, 2, 4 and 24 hours after birth. MAIN OUTCOME MEASURES: LUS videos were graded for aeration and liquid clearance according to a previously validated system. RESULTS: We analysed 1168 LUS video recordings. As assessed by LUS, lung aeration and airway liquid clearance occurred quickly. All infants had an established pleural line at the first examination (median=2 (1-4) min). Only 14% of infants had substantial liquid retention at 10 min after birth. 49%, 78% and 100% of infants had completed airway liquid clearance at 2, 4 and 24 hours, respectively. CONCLUSIONS: In healthy transitioning newborn infants, lung aeration and partial liquid clearance are achieved on the first minutes after birth with complete liquid clearance typically achieved within the first 4 hours of birth. TRIAL REGISTRATION NUMBER: ANZCT 12615000380594.

Lung ultrasound during the initiation of breathing in healthy term and late preterm infants immediately after birth, a prospective, observational study.

INTRODUCTION: Lung ultrasound (LUS) has shown promise for evaluation of newborns with respiratory distress. However, no study has described the appearance of LUS during the initiation of breathing. We used LUS to describe the appearance of the lungs in healthy infants immediately after birth, starting with the infant's first breath, through the first 20min after birth. METHODS: This was a single-center observational study enrolling neonates born at ≥35 weeks. We obtained LUS video recordings with the initiation of breathing. Recordings that captured one of the 1st four breaths after birth were included. We also obtained recordings at 1-10 and 11-20min after birth. Recordings were graded using a modified version of a previously published system, with additional grades to describe the appearance of the lungs prior to establishment of the pleural line. RESULTS: We studied 63 infants, mean gestational age=391/7±2 days, mean weight=3473g±422, 33 infants were delivered vaginally and 30 via cesarean section. We captured the first breath after birth in 28 infants and within the first four breaths from the remaining 35 infants. The pleural line was established by a median of 4 breaths (3-6). At the 1-10min examination, all infants had an established pleural line and 89% demonstrated substantial liquid clearance. At the 11-20min examination, all infants had substantial liquid clearance. CONCLUSION: Establishment of the pleural line, indicating lung aeration and substantial liquid clearance is achieved with the first few breaths after birth in term and near term infants.

HIV infection among paediatric in-patients in Blantyre, Malawi.

To investigate the impact of HIV infection on hospital admission and death we studied children admitted to paediatric medical and surgical wards in Blantyre, Malawi, in March 2000. Unselected children whose parents or guardians consented to HIV testing of the child were recruited and HIV infection was determined by serology, with confirmation in children aged 15 months or less by PCR. We assessed the prevalence of HIV infection by age, clinical diagnosis and outcome of admission. Of 1064 admissions, 991 were tested for HIV infection, and 187 (18.9%) were infected. HIV was most common in children aged less than six months, 53 of 166 (32%). Parents of HIV-infected children were better educated, and more likely to have died, than those of uninfected children. Clinical symptoms and signs were not adequately sensitive or specific to be used for diagnosis of HIV. HIV was common in children with malnutrition (prevalence 40%), lower respiratory tract infection (29%) and sepsis (28%), and less prevalent among children with malaria (11%) or surgical admissions (11%). Almost 30% of HIV-infected children died, compared with 8.9% of uninfected children, and HIV-infected children constituted over 40% of in-patient deaths.

Echocardiographic assessment of left ventricular outflow tract diameter in preterm infants.

Introduction: Left ventricular output (LVO) measurement is an important part of the echocardiographic assessment of cardiac function in preterm infants. The accurate measurement of left ventricular outflow tract diameter (LVOD) is key to the calculation of LVO. Given the lack of an appropriate gold standard, we used right ventricular output (RVO) as the comparator and sought to identify the most accurate method of determining LVO in preterm infants. Methods: We studied stable preterm infants without significant cardiac shunts. LVOD was measured at the aortic valve, the aortic sinus and at the sinotubular junction. LVOs were calculated and the precision and accuracy of each was determined relative to the RVO using the Bland-Altman method. Results: 52 infants were included in this analysis. The mean difference between RVO and LVO was largest when LVOD was measured at the aortic valve and aortic sinus, +106 and -115 ml/kg/min, respectively, and smallest when measured at the sinotubular junction, 9 ml/kg/min. Limits of agreement between RVO and LVO were narrowest when LVOD was measured at the STJ. Conclusion: LVOD measurement at the sinotubular junction provides more precise and accurate measurement of LVO, in comparison to RVO, than measurement at the aortic valve or the aortic sinus.