PubMed Health⌕ Search

Biomedical subjects

Susan Niermeyer

Publications and source records attributed to Susan Niermeyer.

10 recordsLinked to original sources
PubMed2006

Neonatal resuscitation where resources are limited.

This article reviews neonatal resuscitation techniques that can be used where resources are limited. The topic of delayed cord clamping is discussed in detail as an example of an evidence evaluation in which an important segment of the research has been conducted in developing countries. Thermal protection, clearing the airway, and assisted ventilation are discussed as areas in which some evidence exists from research in the developing world, but more work is needed to bring the full benefit of appropriate intervention to newborns in settings where resources are limited.

Airway Obstruction↗
PubMed2006

Volume resuscitation: crystalloid versus colloid.

Adequate circulating volume to maintain mean arterial blood pressure above a critical value is necessary to reverse bradycardia by positive-pressure ventilation during resuscitation after asphyxia. A variety of circumstances can lead to visible or occult blood loss in the perinatal period; however, distinguishing hypovolemic shock from asphyxial shock can be difficult in the delivery room. Small, randomized, controlled trials support the usefulness of isotonic crystalloid rather than albumin-containing solutions for acute volume expansion; ready availability, lower cost, and lesser risk of infectious complications favor the use of isotonic crystalloid as well. No trials have compared crystalloid and colloid for volume expansion in the setting of immediate resuscitation after birth. Further work is needed to refine the approach to infants in whom adequate positive-pressure ventilation fails and to better discriminate between shock on the basis of hypovolemia versus decreased myocardial function.

Asphyxia Neonatorum↗
PubMed2006

Cardiopulmonary pathology among children resident at high altitude in Tintaya, Peru: a cross-sectional study.

Symptomatic high-altitude pulmonary hypertension and structural cardiac abnormalities related to high altitude have been reported previously. However, their true prevalence has not been systematically determined. We assessed clinical indicators of cardiovascular health or disease and correlated them with anatomic and physiologic cardiovascular features in preschool and schoolchildren living at 4000 m. We also estimated the prevalence of cardiovascular problems in the population, with emphasis on symptomatic high altitude pulmonary hypertension and structural cardiopathies. Three hundred and twenty-six children residents of Tintaya, Peru, were cross-sectionally studied. Methods included structured interviews, anthropometry and physical examination, arterial oxygen saturation, hemoglobin determination, electrocardiography, and echocardiography. The prevalence of structural cardiac problems was 1.5%, with less than 1% possibly attributable to high altitude. All children with structural cardiac abnormalities were identified by a focused physical exam prior to echocardiography. None were identified by the health interview. No symptomatic high altitude pulmonary hypertension was identified in the absence of underlying structural anomalies. The prevalence of structural cardiac problems was consistent with data from sea level. Active monitoring of the health status of a pediatric population at high altitude is valuable in the timely detection of cardiac abnormalities. Although our study children enjoyed generally excellent health, comparative, longitudinal studies are warranted to determine the incidence of high altitude cardiopulmonary problems and to identify risk factors and early markers for later disorders associated to life at high altitude. Our findings are applicable to children with some degree of high altitude genetic background and high mobility patterns to lower altitudes and living in comparatively good nutritional and socioeconomic conditions.

Adolescent↗
PubMed2004

Sleep disturbance after rapid ascent to moderate altitude among infants and preverbal young children.

Rapid ascent to high altitude is known to result in sleep disturbances among adults. No data exist regarding the effects of altitude exposure on sleep in children. The objective of this study was to determine the effect of rapid ascent to moderate altitude on sleep in infants and young children. In this prospective study, each child served as his or her own control. Each subject was studied over 7 days and nights. On days 1 and 2, children were studied at home (1601 m), day 3 at a hotel without ascent (travel control), day 4 at home, days 5 and 6 at a hotel after ascent (3109 m), and day 7 at home. Since increased motion is a characteristic of sleep disturbance among infants and young children, continuous measurements of motion were made using an ankle-mounted Actigraph. Thirty children, 17 girls and 13 boys, with a median age of 16.5 months (range = 4 to 33 months) participated in the study. Significant changes in the activity counts, reflecting a sleep disturbance during nocturnal sleep, were noted between the travel control night (20.9 +/- 1.9) and the first night at altitude (29.4 +/- 2.5): p < 0.01. This sleep disturbance is most significant during the first night at altitude and may be similar to sleep disturbance with altitude exposure seen in adults.

Altitude↗
PubMed2003

Intrauterine growth restriction, preeclampsia, and intrauterine mortality at high altitude in Bolivia.

Infant mortality and stillbirth rates in Bolivia are high and birth weights are low compared with other South American countries. Most Bolivians live at altitudes of 2500 m or higher. We sought to determine the impact of high altitude on the frequency of preeclampsia, gestational hypertension, and other pregnancy-related complications in Bolivia. We then asked whether increased preeclampsia and gestational hypertension at high altitude contributed to low birth weight and increased stillbirths. We performed a retrospective cohort study of women receiving prenatal care at low (300 m, Santa Cruz, n = 813) and high altitude (3600 m, La Paz, n = 1607) in Bolivia from 1996 to 1999. Compared with babies born at low altitude, high-altitude babies weighed less (3084 +/- 12 g versus 3366 +/- 18 g, p < 0.01) and had a greater occurrence of intrauterine growth restriction [16.8%; 95% confidence interval (CI): 14.9-18.6 versus 5.9%; 95% CI: 4.2-7.5; p < 0.01]. Preeclampsia and gestational hypertension were 1.7 times (95% CI: 1.3-2.3) more frequent at high altitude and 2.2 times (95% CI: 1.4-3.5) more frequent among primiparous women. Both high altitude and hypertensive complications independently reduced birth weight. All maternal, fetal, and neonatal complications surveyed were more frequent at high than low altitude, including fetal distress (odds ratio, 7.3; 95% CI: 3.9-13.6) and newborn respiratory distress (odds ratio, 7.3; 95% CI: 3.9-13.6; p < 0.01). Hypertensive complications of pregnancy raised the risk of stillbirth at high (odds ratio, 6.0; 95% CI: 2.2-16.2) but not at low altitude (odds ratio, 1.9; 95% CI: 0.2-17.5). These findings suggest that high altitude is an important factor worsening intrauterine mortality and maternal and infant health in Bolivia.

Adult↗
PubMed2003

Physiologic response to moderate altitude exposure among infants and young children.

Substantial numbers of children are exposed to moderate altitude while traveling to mountain resorts with their families. Although there has been extensive study of the adult physiologic response to altitude exposure, few studies of infants and young children exist. This investigation examines the acute physiologic responses to moderate altitude exposure among young children and the relationship of these responses to the development of acute mountain sickness (AMS). Children 3 to 36 months old participated in the prospective observational study, which included baseline measurements at 1610 m and measurements after a 24-h exposure to 3109 m. Measurements included pulse and respiratory rate, end-tidal CO(2), arterial oxygen saturation (pulse oximetry), cerebral tissue oxygenation (St(O2)) by near-infrared spectroscopy, middle cerebral artery resistive index by transcranial Doppler, lateral ventricle volumes (ultrasound), and clinical evaluation for the presence of acute mountain sickness (Children's Lake Louise Score). Twenty-four children (13 girls and 11 boys, age 14.5 +/- 10.2 months) participated. After acute exposure to 3109 m, these children showed an increase in respiratory rate from 45 +/- 13 to 51.9 +/- 15 breaths/min (p < 0.008), accompanied by a decrease of end-tidal CO(2) from 31 +/- 3 to 28 +/- 2 mm Hg (p < 0.001) and a reduction of arterial oxygen saturation from 95 +/- 2 to 91 +/- 2% (p < 0.001). St(O2) also decreased from 78 +/- 8 to 67 +/- 13% (p < 0.001), and this reduction appeared to be related to age (r = 0.58, p < 0.05), with lower saturations found in younger children. No evidence of increased intracranial pressure, as assessed by middle cerebral artery resistive index, was seen during ascent. Seven subjects developed symptoms of AMS; however, no relationship was found between the physiologic changes observed and the presence of symptoms. Ascent from 1610 to 3109 m resulted in tachypnea, relative hypoxia, hypocapnia, and a reduction in cerebral tissue oxygenation (St(O2)). The reduction in St(O2) appeared to be related to age, with infants appearing to be the most susceptible to cerebral tissue oxygen desaturation at high altitude. No relationship appears to exist between the presence of AMS and the physiologic measurements.

Age Factors↗
PubMed2003

Cardiopulmonary transition in the high altitude infant.

The perinatal cardiopulmonary transition at high altitude differs from that at sea level because oxygen plays a fundamental role in the developmental changes from fetus to newborn infant. Under conditions of high altitude hypoxia, arterial oxygen saturations are lower, breathing patterns and maturation of respiratory control reflexes differ, and regression of fetal characteristics of the pulmonary vasculature proceeds more slowly. Several aspects of transition vary not only with postnatal age and altitude, but also with population group, suggesting an effect of genetic adaptation on perinatal physiology. Exposure to chronic high altitude hypoxia during the perinatal transition also results in apparent lifelong alterations in respiratory reflex responses and pulmonary vasoreactivity. Disruption of the normal process of cardiopulmonary transition can result in symptomatic high altitude pulmonary hypertension. The exaggerated hypoxemia associated with acute respiratory infections in young infants still undergoing transition contributes to infant mortality at high altitude.

Adaptation, Physiological↗
PubMed2002

Evaluation of diagnostic criteria and incidence of acute mountain sickness in preverbal children.

OBJECTIVE: The Children's Lake Louise Score (CLLS) established the diagnostic criteria for acute mountain sickness (AMS) in preverbal children. Prospective application of the CLLS and interobserver agreement for the score had not been evaluated in a controlled trial. A study of children and their parents was used to evaluate the CLLS and determine the incidence of AMS in preverbal children. METHODS: A prospective, controlled trial. Children > or =3 months and < or =36 months old and their parents living below 1645 m were studied over 7 separate days. The CLLS, measured daily by the mother as well as by the father on days 5 and 6, is the sum of scores for fussiness (FS), eating (E), playfulness (P), and sleep (S). Children were studied on days 1 and 2 at home, on day 3 after travel without altitude gain to a hotel, on day 4 at home, on days 5 and 6 at a hotel at 3109 m, and on day 7 at home. Using our previous criteria, AMS was diagnosed if the CLLS was > or =7 with both the FS > or =4 and the E + P + S > or =3. Agreement between mothers' and fathers' CLLS values was measured with the kappa statistic (K). Adults were also evaluated for AMS by the CLLS on days 5 and 6. RESULTS: Thirty-seven children (mean age +/- SD = 16.5+/-10.5 months; 21 girls) participated, and AMS occurred in 7 of them (19%; 95% CI, 8.35%). Among 33 adults, 8 (24%; 95% CI, 9.39%) had AMS. Although the agreement of the parents on the CLLS components was poor, the agreement on the classification of AMS between mother and father was excellent (K = .67; P < .001), with both parents' scores exceeding the CLLS threshold for AMS. CONCLUSIONS: In this prospective trial, parents demonstrated excellent interobserver agreement for independent use of the CLLS to detect AMS. Consistent with our previous retrospective study, the incidence of AMS at moderate altitude in preverbal children (19%) was similar to that in adults (24%).

Adult↗
PubMedDate not supplied

Cross-sectional study of echocardiographic characteristics in healthy children living at high altitude.

Non-echocardiographic studies in healthy high altitude children have shown right ventricle predominance during infancy and childhood, associated to asymptomatic pulmonary hypertension and an increased pulmonary artery pressure. Systematic studies on echocardiography in such children have not been performed. In a cross-sectional study, we measured right and left heart morphologic and functional parameters, through M-mode, two-dimensional Doppler, and color Doppler echocardiographies, in a population of 321 healthy children ranging in age from 2 months to 19 years and living at high altitude (Tintaya, Peru, 4,100 m). Structured ad-hoc interviews were done to obtain information on medical history, patterns of exposure to high altitude of children and their parents and grandparents, place and altitude of pregnancy and birth, and housing conditions. A complete physical examination was performed before echocardiography. Hemoglobin concentration, pulse oximetry, and anthropometry were measured in all participating children. The right and left heart morphologic and functional echocardiographic measurements expressed by age and by body surface area were generally similar to sea-level reference populations. They were not consistently influenced by sex, nutritional status, chest dimensions, pulse oximetry, hemoglobin concentration, ethnicity, length of residence at high altitude, or parental history of exposure to high altitude. Most children had at least some degree of high-altitude ancestry as assessed by ethnicity and history of parental exposure to altitude. The cardiovascular development at high altitude in children with some degree of high-altitude ancestry seems to follow a pattern similar to sea-level children. The results can be used as reference values to interpret individual echocardiographic studies in comparable children living in similar settings.

Adolescent↗