Soporte ventilatorio no invasivo como puente hacia el trasplante pulmonar: reporte de un caso / Bridging to lung transplant using noninvasive ventilatory support: a case report

El soporte ventilatorio no invasivo es una herramienta que ha demostrado mejorar la sobrevida de pacientes con falla muscular de la bomba respiratoria y el manejo de enfermedades pulmonares crónicas, incluso la ventilación no invasiva nocturna ha servido de puente hacia el trasplante pulmonar. Se presenta el caso de una adolescente de 14 años con enfermedad pulmonar crónica hipoxémica severa y falla ventilatoria secundaria, que requirió ventilación prolongada y traqueostomía en espera de trasplante pulmonar. Luego de reevaluar indemnidad de la vía aérea fue decanulada a soporte ventilatorio no invasivo, con uso alternado de mascarilla nasal nocturna y pieza bucal diurna, permitiendo descanso muscular respiratorio eficiente, y mejoría de flujo de tos con técnicas de apilamiento de aire. Este plan permitió una decanulación segura y realizar soporte continuo ventilatorio no invasivo con un programa de rehabilitación cardiorrespiratorio. Generalmente, el soporte ventilatorio no invasivo se utiliza en trastornos primarios de la bomba respiratoria. En este caso, se indicó para enfermedad pulmonar crónica hipoxémica, mostrando claros beneficios con oxigenación adecuada, buen rendimiento cardiovascular con mejor tolerancia al ejercicio y entrenamiento en el escenario de preparación al trasplante pulmonar.

Noninvasive Ventilatory Support has demonstrated to improve survival of patients with ventilatory pump muscle failure and nocturnal noninvasive ventilation is useful in chronic lung disease, even bridging to lung transplant. We present a 14 years old girl with severe hypoxemic chronic lung disease and secondary ventilatory failure, who required continuous long-term ventilation and underwent a tracheostomy waiting for lung transplant. After reevaluated the airway patency the patient was decannulated to Noninvasive Ventilation Support, alternating nocturnal nasal mask with diurnal mouth piece in order to provide efficient respiratory muscle rest, made air stacking and improved cough flow. This plan allows safe decannulation to continuous Noninvasive Ventilatory Support tailoring a rehabilitation cardiorespiratory program. Usually, Noninvasive Ventilation Support is prescribed for primary respiratory pump muscles failure, but in this case, it was applied for a hypoxemic chronic lung disease. Clear benefits were observed leading to appropriate oxygenation, good cardiovascular performance with better tolerance to exercise for training in the preparatory scenario of a lung transplant.

Rehabilitación respiratoria para pacientes con distrofia muscular de Duchenne en etapas de pérdida de la marcha / Respiratory rehabilitation for patients with Duchenne muscular dystrophy in stages of loss of gait

Duchenne muscular dystrophy (DMD) is one of the most common neuromuscular diseases. Its evolution with well-defined stages related to motor and functional alterations, allows easily establishing relationships with respiratory function through a simple laboratory assessment including vital capacity (VC) measurements as well as peak cough flows. Without any treatment with respiratory rehabilitation, the main cause of morbidity and mortality is ventilatory failure, secondary to respiratory pump muscles weakness and inefficient cough. The VC plateau is reached during the non-ambulatory stages, generally after 13 years old. Respiratory rehabilitation protocols, including air stacking techniques, manual and mechanical assisted coughing and non-invasive ventilatory support, can effectively addressed the VC decline as well as the decrease in peak cough flows, despite advancing to stages with practically non-existent lung capacity. Non-invasive ventilatory support may be applied after 19 years old, initially at night and then extending it during the day. In this way, survival is prolonged, with good quality of life, avoiding ventilatory failure, endotracheal intubation and tracheostomy. This article proposes staggered interventions for respiratory rehabilitation based on the functional stages expected in the patient with DMD who has lost ambulation.

La distrofia muscular de Duchenne (DMD) es una de las enfermedades neuromusculares más frecuentes. Su curso evolutivo con etapas de declinación en la funcionalidad motora bien definidas, permite fácilmente establecer relaciones con la función respiratoria a través de un laboratorio de evaluación sencilla, básicamente de la capacidad vital (CV) y la capacidad tusígena. Sin intervenciones en rehabilitación respiratoria, la principal causa de morbimortalidad es la insuficiencia ventilatoria secundaria a debilidad de músculos de la bomba respiratoria e ineficiencia de la tos. En las etapas no ambulantes, se alcanza la meseta de la CV, generalmente después de los 13 años, su declinación junto con la disminución de la capacidad tusígena puede ser enfrentada efectivamente con la utilización de protocolos de rehabilitación respiratoria. Estos deben considerar la restitución de la CV con técnicas de insuflación activa o apilamiento de aire, tos asistida manual y mecánica, más soporte ventilatorio no invasivo, inicialmente nocturno después de los 19 años y luego diurno, pese a avanzar a etapas con capacidad pulmonar prácticamente inexistente. De esta manera, se prolonga la sobrevida, con buena calidad de vida, evitando el fallo ventilatorio, eventos de intubación endotraqueal y traqueostomía. Este artículo, hace propuestas escalonadas de intervención en rehabilitación respiratoria basadas en las etapas funcionales esperables en el paciente con DMD que ha perdido la capacidad de marcha.

Cuidados respiratorios de los pacientes con atrofia muscular espinal / Respiratory care approach for patients with spinal muscular atrophy

Spinal Muscular Atrophy (SMA) is a disease of the anterior horn of the spinal cord, which causes muscle weakness that leads to a progressive decrease in vital capacity and diminished cough flows. Respiratory morbidity and mortality are a function of the degree of respiratory and bulbar-innervated muscle. The former can be quantitated by the sequential evaluation of vital capacity to determine the lifetime maximum (plateau) and its subsequent rate of decline, progressing to ventilatory failure. SMA types 1 and 2 benefit from non-invasive respiratory care in early childhood and school age, improving quality and life expectancy. This document synthesizes these recommendations with special reference to interventions guided by stages that include air stacking, assisted cough protocols, preparation for spinal arthrodesis and non-invasive ventilatory support, even in those patients with loss of respiratory autonomy, minimizing the risk tracheostomy. Failure to consider these recommendations in the regular assessment of patients reduces the offer of timely treatments.

La Atrofia Muscular Espinal (AME) es una enfermedad genética del asta anterior de la medula espinal, que cursa con debilidad muscular progresiva. La intensidad y precocidad de la debilidad muscular presenta diferentes grados de afectación de los grupos musculares respiratorios, determinando la meseta en la capacidad vital y progresión a la insuficiencia ventilatoria, como también el compromiso de los músculos inervados bulbares. Los AME tipo 1 y 2, se benefician con cuidados respiratorios no invasivos en la infancia temprana y edad escolar, mejorando la calidad y esperanza de vida. Este documento sintetiza dichas recomendaciones, con especial referencia a intervenciones guiadas por etapas, que incluyan apilamiento de aire, protocolos de tos asistida, preparación para la artrodesis de columna y soporte ventilatorio no invasivo, incluso en aquellos pacientes con pérdida de la autonomía respiratoria, minimizando el riesgo de traqueostomía. La no consideración de estas recomendaciones en la valoración regular de los pacientes resta la oferta de tratamientos oportunos.

Consenso chileno para la atención integral de niños y adultos con fibrosis quística

Resumen La Fibrosis Quística (FQ) es la enfermedad hereditaria de pronóstico reservado más frecuente en raza blanca. Desde el año 2003, Chile inicia un Programa Nacional de Fibrosis Quística, de carácter integral, dirigido por la Unidad de Salud Respiratoria del Ministerio de Salud. Hasta la fecha, los principales resultados del Programa registran una significativa mayor sobrevida (promedio 27 años) y una significativa reducción en la edad de diagnóstico de los pacientes ingresados desde 2006 en adelante. El acceso a la canasta GES (Garantías Explícitas en Salud), la implementación del tamizaje neonatal en algunas regiones del país, la organización y la constitución de equipos entrenados en FQ de diversas especialidades, ha contribuido a mejorar los resultados. Si bien las principales manifestaciones son del aparato respiratorio y digestivo, el carácter multisistémico de la FQ obliga a conocer los distintos aspectos involucrados en su manejo, a fin de optimizar los resultados del tratamiento y los recursos invertidos, tanto en el sector público como privado. Este documento es una revisión y actualización sobre los principales aspectos del diagnóstico, seguimiento y tratamiento de las manifestaciones respiratorias y no respiratorias de la FQ.

Cystic Fibrosis (CF) is the most frequent hereditary disease in whites, with a reserved prognosis. Since 2003, Chile began a comprehensive National Cystic Fibrosis Program, directed by the Respiratory Health Unit of the Ministry of Health. To date, the main results of the Program record a significantly longer survival (average 27 years) and a significant reduction in the age of diagnosis of patients admitted from 2006 onwards. Access to Chilean Explicit Health Guarantees, the implementation of neonatal screening in some regions of the country, the organization and setting up of CF-trained teams of various specialties, has contributed to improving results. Although the main manifestations are of the respiratory and digestive system, the multisystemic nature of CF makes it necessary to know the different aspects involved in its management, in order to optimize the results of the treatment and the resources invested, both in the public and private sectors. This document is a review and an update on the main aspects of the diagnosis, monitoring and treatment of the respiratory and non-respiratory manifestations of CF.

Consenso chileno para la atención integral de niños y adultos con fibrosis quística / Chilean consensus for the integral care of children and adults with cystic fibrosis

Cystic Fibrosis (CF) is the most frequent hereditary disease in whites, with a reserved prognosis. Since 2003, Chile began a comprehensive National Cystic Fibrosis Program, directed by the Respiratory Health Unit of the Ministry of Health. To date, the main results of the Program record a significantly longer survival (average 27 years) and a significant reduction in the age of diagnosis of patients admitted from 2006 onwards. Access to Chilean Explicit Health Guarantees, the implementation of neonatal screening in some regions of the country, the organization and setting up of CF-trained teams of various specialties, has contributed to improving results. Although the main manifestations are of the respiratory and digestive system, the multisystemic nature of CF makes it necessary to know the different aspects involved in its management, in order to optimize the results of the treatment and the resources invested, both in the public and private sectors. This document is a review and an update on the main aspects of the diagnosis, monitoring and treatment of the respiratory and non-respiratory manifestations of CF.

La Fibrosis Quística (FQ) es la enfermedad hereditaria de pronóstico reservado más frecuente en raza blanca. Desde el año 2003, Chile inicia un Programa Nacional de Fibrosis Quística, de carácter integral, dirigido por la Unidad de Salud Respiratoria del Ministerio de Salud. Hasta la fecha, los principales resultados del Programa registran una significativa mayor sobrevida (promedio 27 años) y una significativa reducción en la edad de diagnóstico de los pacientes ingresados desde 2006 en adelante. El acceso a la canasta GES (Garantías Explícitas en Salud), la implementación del tamizaje neonatal en algunas regiones del país, la organización y la constitución de equipos entrenados en FQ de diversas especialidades, ha contribuido a mejorar los resultados. Si bien las principales manifestaciones son del aparato respiratorio y digestivo, el carácter multisistémico de la FQ obliga a conocer los distintos aspectos involucrados en su manejo, a fin de optimizar los resultados del tratamiento y los recursos invertidos, tanto en el sector público como privado. Este documento es una revisión y actualización sobre los principales aspectos del diagnóstico, seguimiento y tratamiento de las manifestaciones respiratorias y no respiratorias de la FQ.

Actualización en kinesiología respiratoria en pacientes con fibrosis quística / Update of chest physiotherapy in cystic fibrosis patients

Chest physiotherapy is an essential component of cystic fibrosis treatment. Its aim is to delay lung deterioration and preserve physical function, improving quality of life and long-term results. It is possible to proceed early, even when the child is asymptomatic.The therapist must be a competent professional, able to participate in a health care team and to make therapeutic decisions. Currently, the therapist is responsible for optimizing mucociliary clearance, but in, addition, their work has extended to education, aerosol therapy, physical activity recommendations, non-invasive ventilatory support, oxygen therapy.This article provides a general description of the chest therapist proceedings related to the integral management of cystic fibrosis

La kinesioterapia respiratoria es parte del tratamiento integral de la Fibrosis Quística. Con ella, apuntamos a retrasar el deterioro pulmonar y preservar la función física, mejorando la calidad de vida y los resultados a largo plazo. Es posible actuar de manera precoz, incluso cuando el niño es asintomático.Es de importancia que el kinesiólogo que trate a pacientes con Fibrosis Quística sea un profesional competente, con capacidad de formar parte de un equipo de salud y participar activamente en las decisiones terapéuticas requeridas, ya que en la actualidad, el kinesiólogo ha ampliado su labor, ya no solo circunscribiéndose a las técnicas manuales e instrumentales para optimizar el drenaje bronquial. Este articulo entrega una descripción general del actuar del kinesiólogo en el manejo integral del paciente con Fibrosis Quística

Validation and adaptation of rapid neurodevelopmental assessment instrument for infants in Guatemala.

BACKGROUND: Timely detection of neurodevelopmental impairments in children can prompt referral for critical services that may prevent permanent disability. However, screening of impairments is a significant challenge in low-resource countries. We adapted and validated the rapid neurodevelopmental assessment (RNDA) instrument developed in Bangladesh to assess impairment in nine domains: primitive reflexes, gross and fine motor development, vision, hearing, speech, cognition, behaviour and seizures. METHODS: We conducted a cross-sectional study of 77 infants (0-12 months) in rural Guatemala in July 2012 and July 2013. We assessed inter-rater reliability and predictive validity between the 27-item RNDA and the 325-item Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III) and concurrent validity based on chronic malnutrition, a condition associated with neurodevelopmental impairments. For both RNDA and BSID-III, standardized scores below 80 were defined as borderline impairment. RESULTS: Children came from rural households (92%), were born to indigenous women of Mayan descent (73%) and had moderate or severe growth stunting (43%). Inter-rater reliability for eight RNDA domains was of moderate to high reliability (weighted κ coefficients, 0.49-0.99). Children screened positive for impairment in fine motor (17%) and gross motor (14%) domains using the RNDA. The RNDA had good concurrent ability; infants who were growth stunted had higher mean levels of impairment in gross motor, speech and cognition domains (all p < 0.001). The RNDA took 20-30 min to complete compared with 45-60 min for BSID-III. CONCLUSIONS: Wide-scale implementation of a simple, valid and reliable screening tool like the RNDA by community health workers would facilitate early screening and referral of infants at-risk for neurodevelopmental impairment.

Photogrammetry of fetal breathing movements during the third trimester of pregnancy: observations in normal and abnormal pregnancies.

OBJECTIVE: To evaluate parameters of fetal breathing movements-displacement of the fetal abdominal wall during inspiration and expiration, time of inspiration and expiration and speed of inspiration and expiration-between 30 and 36 weeks' gestation in normal pregnancies, and in those complicated by gestational diabetes or maternal hypertension. METHODS: Three categories of pregnancy were investigated: 49 were normal, 16 had pregnancy-induced diabetes and 10 were hypertensive. According to their gestational age, the patients were divided into two groups: Group A between 30 and 32 weeks' gestation and Group B between 33 and 36 weeks. Using photogrammetry and a computer-operated algorithm, six parameters of fetal breathing movements were investigated. RESULTS: There were significant differences in the various fetal parameters measured among the three categories of pregnant women. Up until 32 weeks of gestation, the displacements during inspiration and expiration were larger, the speeds of inspiration and expiration were higher, and the times for inspiration and expiration were shorter in the diabetic and hypertensive groups than in the normal group. In the later period, between 33 and 36 weeks, fetuses of pregnancy-induced diabetic patients showed the lowest inspiration and expiration times and the highest speeds of inspiration and expiration. CONCLUSIONS: Photogrammetry in conjunction with a computer-operated algorithm can be used to assess fetal breathing movements. There are significant differences in fetal breathing movements between normal pregnancies and those that are complicated by gestational diabetes or hypertension.

La escala de Tal como test diagnóstico y el diagnóstico clínico como gold standard en el síndrome bronquial obstructivo del lactante / No disponible

Objetivo: evaluar la utilidad diagnóstica del índice de Tal aplicado por profesional sanitario no médico en el ámbito extrahospitalario como test diagnóstico y la “impresión clínica” como gold standard en el diagnóstico del síndrome bronquial obstructivo del lactante. Material y métodos: estudio observacional de test diagnóstico de casos consecutivos. Resultados: la escala de Tal presenta una sensibilidad del 77%, (IC 95%, 70-82%), una especificidad del 88,4% (IC 95%, 84-92%), un valor predictivo positivo del 87% (IC 95%, 81- 91%) y un valor predictivo negativo del 80% (IC 95% 74-85%). Conclusiones: en esta muestra el índice de Tal efectuado por profesionales sanitarios no médicos demuestra tener una buena correlación en el diagnóstico del lactante con obstrucción bronquial

Objective: to evaluate the Tal score like diagnostic test applied by non-medical professionals and “clinical impression” (clinical diagnosis) like Gold Standard in the diagnosis of infants with acute wheezing bronchitis. Material and methods: a diagnostic test study. Results: the sensitivity of Tal score was 77% (confidence interval 95% [CI] 70-82%) and the specificity 88.4% (CI 95% 84-92%). The positive predictive value was 87% (CI 95% 81- 91%) and the negative predictive value 80% (IC 95% 74-85%). Conclusions: in this study the Tal score as diagnostic test applied by non-medical professionals compared with “clinical impression” (clinical diagnosis) like Gold Standard show a good correlation in the diagnosis of infants with acute wheezing bronchitis

Ultrasound antenatal diagnosis of cleft palate by a new technique: the 3D "reverse face" view.

OBJECTIVE: To assess the clinical value of a novel three-dimensional (3D) ultrasound technique, the reverse face view (3D RF view), in the antenatal categorization of facial clefting and in particular clefting of the hard palate. METHODS: Eight cases of suspected orofacial clefting were examined by 3D surface rendering. The fetal lips and alveolar ridge were examined in the frontal plane and the face was then rotated through 180 degrees on the vertical axis to examine the secondary palate by the 3D RF view. RESULTS: In each case described, we were able to visualize the fetal face, lips and palate and make an antenatal diagnosis as to whether the palate was affected. In all cases, the antenatal diagnosis was subsequently confirmed. In one case with a left-sided cleft in the lips and alveolar ridge and an intact hard palate, the correct diagnosis was made but a cleft in the soft palate was missed. CONCLUSION: Although clefts of the lips and alveolar ridge are readily diagnosed on high-quality antenatal ultrasound, visualization of the fetal palate using existing techniques is unreliable. In the patients described here, the 3D RF technique allowed relatively straightforward assessment of the fetal palate with a high degree of accuracy.

Clinical impact of first and early second trimester fetal echocardiography on high risk pregnancies.

OBJECTIVE: To evaluate the clinical impact of fetal echocardiography before 16 weeks' gestation on the management of pregnancies with fetuses at risk of congenital heart disease. DESIGN AND SETTING: Observational study in a fetal medicine unit. PARTICIPANTS AND METHODS: 222 consecutive women with high risk pregnancies (230 fetuses) underwent transabdominal fetal echocardiography at a median gestation of 14(+1) weeks. For 10%, transvaginal scans were also performed. Criteria for normal scans were normal sequential segmental analysis, symmetrical four chamber view, normal semilunar valves, arterial outflow tracts, and ductal and aortic arches. Early scans were compared with mid-second trimester fetal echocardiography. Postmortem and postnatal data were added. Adverse pregnancy outcomes were diagnosis of a major cardiac or extracardiac abnormality, chromosomal defects, intrauterine death, or termination of pregnancy. RESULTS: There were 21 abnormal cardiac scans (9%): 14 major structural defects (eight isolated, six with chromosomal or extracardiac abnormalities) in pregnancies resulting in three live births, one intrauterine death, and 10 terminated pregnancies. Seven scans showed asymmetry between right and left sided structures (two isolated, five with chromosomal or extracardiac abnormalities); six of the seven pregnancies were terminated. The scans were normal in 199 cases (87%). Cardiac follow up of 184 of 199 babies (93%) confirmed situs and connections. One case each of pulmonary stenosis and ventricular septal defect requiring postnatal intervention were diagnosed at later scans. In 28 of 199 (14%) babies there was a non-cardiac adverse outcome. First examination was not diagnostic for 10 (4%). CONCLUSION: Early fetal echocardiography in high risk pregnancies was diagnostic in 96%. Abnormal cardiac scans (isolated in 48%, major structural defects in 67%) led to termination of pregnancy in 76%. Most cardiac scans were normal, allowing family reassurance. The high number of adverse outcomes with normal cardiac anatomy stresses the need for a multidisciplinary approach to early fetal echocardiography.

The biology of foetal development and injury.

This oversimplified view of foetal development and the risk to injury aims to highlight the following: assuming there is a normal environment, gene expression will generate a protein chain that should fold to the expected stereological shape to function normally. Here we must take into consideration the important role played by external (environmental) factors. Abnormal organogenesis or foetal injury are, in all likelihood, due to abnormal genes or genes expressing themselves 'out of sinc', that is to say 'outside' their time allocated for expression. This type of injury is difficult to correct. Morphogenesis, or the continuous remodelling of formed organ/systems can be more amenable to correction since the basic layout of the organ already exists. The common denominator to organogenesis and morphogenesis, at cellular/tissue levels, is the harmonic interplay between cell multiplication, cell migration, cell differentiation, cell death, the generation of intercellular matrix and its resorption. All of this must take place at the 'right time'. Any departure from it may lead to injury, whether clinically detectable or not.

Sonographic diagnosis of spina bifida at 12 weeks: heading towards indirect signs.

Retrospective examination of ultrasound images obtained at 12 weeks of gestation in two fetuses with spina bifida demonstrated retraction of the frontal bones, resulting in an acorn-shaped head, the cerebral peduncles appearing parallel to each other. These craniocerebral signs may improve the accuracy of first-trimester diagnosis of spina bifida by sonography.

The human ductus venosus between 13 and 17 weeks of gestation: histological and morphometric studies.

BACKGROUND: Doppler studies of the ductus venosus are increasingly being integrated in the assessment of fetal well-being. Establishing the precise morphology and structure of the ductus venosus would provide a better understanding of Doppler findings during fetal adaptation. There is conflicting evidence from previous studies about the structure of the ductus venosus, especially with regard to the presence of a sphincter at the ductus venosus inlet. The aim of this study was to examine the morphology and histological structure of the ductus venosus wall and surrounding tissues at 13-17 weeks' gestation. DESIGN: This was a prospective study on 28 fetuses obtained from medical termination of pregnancies between 13 and 17 weeks' gestation. Scanning electron microscopy and histological and immunohistochemical studies were carried out on ductus venosus sections obtained from different spatial planes. RESULTS: The inlet of the ductus venosus contained a shelf which was rich in elastin, but devoid of any evidence of a smooth muscle sphincter. The isthmus of the ductus venosus above the inlet was narrowed, giving the lumen of the vessel an hourglass appearance. The endothelial surface of the ductus venosus, above the level of the inlet, showed longitudinal corrugations along its entire length. Longitudinally arranged elastin fibers were also seen along the length of the ductus venosus. A single layer of longitudinally arranged smooth muscle cells was present along the entire length of the ductus venosus, with occasional individual nerve cells visible in this layer. CONCLUSIONS: The presence of an elastin-rich shelf and a narrow ductus venosus inlet orifice may act to accelerate flow from the portal sinus into a high-velocity system in the ductus venosus. The abundant elastin fibers in the adventitia of the ductus venosus may help antegrade wave propagation by elastic recoil. This study clearly demonstrates the lack of an anatomical smooth muscle sphincter at the ductus venosus inlet. However, the combination of endothelial corrugations and innervated smooth muscle support the hypothesis that the ductus venosus is an actively regulated vessel with the capacity to rapidly change diameter along its entire length in response to certain stimuli.

Limitations of using first-trimester nuchal translucency measurement in routine screening for major congenital heart defects.

OBJECTIVE: To evaluate the effectiveness of nuchal translucency (NT) measurement in screening for major congenital heart disease (CHD) in chromosomally normal fetuses. DESIGN: A population based cohort study of all women having fetal NT measurement at 10-14 weeks of gestation in an unselected population over a 3-year period. The outcome measure was the identification of major CHD in chromosomally normal pregnancies either antenatally or postnatally. RESULTS: Major defects of the heart and great arteries were identified in 26 out of 7339 pregnancies (prevalence 3.5 per 1000 pregnancies). Out of 26 cases, only four (sensitivity 15.4%, 95% CI 4-35) were in the group of 258 pregnancies (3.5%) with increased NT of > or = 2.5 mm. The prevalence of major CHD increased from 3.1 per 1000 for NT < 2.5 mm to 50 per 1000 for NT > or = 3.5 mm (likelihood ratio of 14.1, 95% CI 4.2-47.9). The positive and negative predictive values for NT > or = 2.5 mm were 1.6% and 99.7%, respectively. CONCLUSIONS: The prevalence of major CHD in this study was 3.5 per 1000, suggesting that ascertainment of CHD in our study population was thorough. Fetuses with NT measurements > or = 3.5 mm have a significantly increased risk of major CHD, and this identifies a subgroup of high-risk patients in whom early fetal echocardiography would be advocated. The low sensitivity of NT for major CHD in the general population, however, indicates that NT cannot be relied on as the sole or major screening tool for this condition as previously reported.

Fetal Doppler velocimetry at high altitude.

OBJECTIVES: To determine impedance and velocity characteristics of the fetal circulation using Doppler ultrasound, at extremely high altitude (4300 m) in the Peruvian Andes compared to an ethnically similar population at sea level. METHODS: This was a cross-sectional study of 196 women resident at high altitude (Cerro de Pasco, 4300 m above sea level) and 196 women resident at sea level (Lima) with normal singleton pregnancies. Pulsatility index (PI), maximum velocity (Vmax) and minimum velocity (Vmin) in the umbilical artery, the descending aorta, the middle cerebral artery and the ductus venosus were compared between the two populations using fractional polynomial regression analysis. RESULTS: The PI was higher at high altitude than at sea level in the umbilical artery (regression coefficient = 0.112, P < 0.001), and not significantly different in the descending aorta, middle cerebral artery and ductus venosus. Vmax was lower at high altitude than at sea level in all three arterial vessels assessed; Vmin was lower in two: the umbilical artery and the descending aorta. The high-altitude/sea-level ratios for umbilical artery Vmax and Vmin were 0.93 and 0.82, respectively (P < 0.001 for each), the ratios for descending aorta Vmax and Vmin were 0.93 and 0.89, respectively (P = 0.003 and P < 0.001, respectively), and the regression coefficient for the middle cerebral artery Vmax was -2.844 (P = 0.003). There was no significant difference in the middle cerebral artery Vmin or in the ductus venosus Vmax and Vmin. CONCLUSIONS: Despite the lower ambient oxygen at high altitude and an increase in umbilical artery PI, the fetal circulation does not exhibit a 'brain sparing effect'. This and the overall decrease in blood flow velocities in the fetal circulation at high altitude may be due to the increased fetal hematocrit, which will result in increased blood viscosity.

Maternal uterine artery Doppler studies at high altitude and sea level.

OBJECTIVE: To determine uterine artery impedance using Doppler in the second and third trimesters at sea level and at high altitude. METHODS: Uterine artery resistance and pulsatility indices (RI and PI, respectively) were obtained by Doppler velocimetry from 242 women in Cerro de Pasco (4300 m altitude) and 200 women in Lima (sea level), all with normal singleton pregnancies between 14 and 40 weeks of gestation. Impedance indices at high altitude and sea level were compared using fractional polynomial regression analysis. RESULTS: Impedance to uterine artery blood flow was lower at high altitude than at sea level (for PI ratio Lima/Cerro de Pasco = 1.06; P = 0.011). If gestation bands were compared, the difference was significant up to 25 weeks. CONCLUSION: At high altitude, pregnancy is associated with lower uteroplacental impedance than at sea level. This may reflect a compensatory mechanism of uteroplacental development to lower oxygen tension associated with altitude.

The anatomy of the umbilical, portal and hepatic venous systems in the human fetus at 14-19 weeks of gestation.

BACKGROUND: Ultrasound imaging of the fetal ductus venosus is becoming increasingly commonplace in clinical practice. The true anatomical relationships of the fetal umbilical and portal venous systems have not been clearly defined due to paucity of published data on the relevant anatomy. This has led to confusing terminology when describing the fetal umbilical, portal and hepatic circulations. The aim of the present study was to examine and document the anatomy of the umbilical, portal and hepatic venous systems and to propose a standardized nomenclature. METHODS: This was a prospective study on 11 fetuses obtained from medical termination of pregnancies between 14 and 19 weeks of gestation. The liver was microdissected to expose the branching pattern and anatomical relations of the umbilical, portal and hepatic venous systems. RESULTS: A wide L-shaped venous confluence at the terminal end of the umbilical vein, termed the portal sinus, was identified. The portal sinus was connected to the right and left hepatic lobes, by the right and left intrahepatic portal veins, respectively. The extrahepatic portal vein drained into the portal sinus just before the origin of the right intrahepatic portal vein. The ductus venosus, a branchless straight vessel, originated from the portal sinus and ascended steeply in the direction of the diaphragm. Numerous small vessels draining the liver converged into three main hepatic veins, which open into the subdiaphragmatic vestibulum. CONCLUSION: Based on detailed sequential anatomical dissection and clear illustrations, the present study documents the anatomy of the umbilical, portal and hepatic venous systems. Taking into account the embryological origin of the vessels, a new anatomically appropriate and simplified nomenclature of these venous systems is proposed. In clinical practice, the consistent use of the suggested terminology would allow collection of comparable data between units and enable operators to be confident of which vessels they are sampling by Doppler ultrasound.