Lower Limit Of Viability Research Articles

An Immature Science: Intensive Care for Infants Born at ≤23 Weeks of Gestation

The gestational age boundary separating infants considered too immature for intensive care from infants who may benefit has shifted dramatically during the past 50 years. In 1971, a widely used neonatology textbook stated that “The lower limit of viability is probably around 28 weeks, at which time most infants weigh two pounds, four ounces (1000 g).” 1 Schaffer A. Avery M.E. Diseases of the newborn. Saunders, Philadelphia (PA)1971: 23 Google Scholar Today, the most immature infants routinely cared for by neonatologists in some parts of the world are born at 22 or 23 weeks of gestation, with many weighing less than a pound. 2 Backes C.H. Rivera B.K. Pavlek L. Beer L.J. Ball M.K. Zettler E.T. et al. Proactive neonatal treatment at 22 weeks of gestation: a systematic review and meta-analysis. Am J Obstet Gynecol. 2021; 224: 158-174 Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar

Prospective study of early and late outcomes of extremely low birthweight in Central Saudi Arabia

BackgroundSurvival of preterm neonates has steadily improved over the past five decades, due to changes in the neonatal intensive care. However, in Saudi Arabia, there are no written guidelines on the definition of the lower limit of viability, and there has been a call for such a limit. The aims of this study were: (1) to determine lower limits of viability and survival in extremely low birthweight (ELBW) infants, and (2) to determine incidence of neurodevelopmental and cognitive abnormalities within 3–6 years after birth.MethodsProspective study of all live inborn ELBW infants admitted to the neonatal unit of King Abdulaziz Medical City, Riyadh, Saudi Arabia, within 3 years [between January 1st, 2005 and December 31st, 2007] was conducted (n = 117). Data were collected on demographic and birth data, neonatal complications & interventions and death on discharge. Prospective follow up of all survivors was done, within 6 years after birth, to assess the outcome in terms of neurodevelopmental and cognitive abnormalities. Predictors of survival were determined using logistic regression model. Significance was considered at p-value ≤0.05.ResultsOf all ELBW infants, 41% died before discharge. Survival rate was directly correlated with gestational age (GA) and birthweight (p < 0.05). The 50% limits of viability were those at 25 weeks’ gestation or with > 600 g. After adjusting for possible confounders, significant predictors of survival were birthweight (p = 0.001) and Apgar score (p < 0.001). The following impairments were reported during follow up of survivors: developmental delay (39.2%), cerebral palsy (36.2%), speech problems (33.3%), wasting (12.5%), intellectual disability (10%), visual problems (6.6%) and hyperactivity (5.6%).ConclusionMore than one-third of ELBW died before discharge from NICU, and two-thirds of survivors had one or more neurodevelopmental and/or cognitive abnormalities during their first 6 years of life. The 50% limits of viability of ELBW infants were those at week 25 of gestation or with a birthweight of more than 600 g. Birthweight could be considered as more valid than gestational age in the prediction of viability of ELBW infants. The process of care of ELBW infants in Saudi Arabia may need to be revisited taking these findings into consideration.

The Toxigen Initiative

Supplemental oxygen plays a critical role in the care of infants born at the lower limits of viability, but not without the risk of morbidity resulting from high levels or prolonged exposure. The purpose of this quality improvement project was to reduce exposure to hyperoxia as evidenced by SpO2 values within the established target range (88%-92%) among very preterm infants (VPIs) in a level 3 neonatal intensive care unit (NICU). Reducing exposure to hyperoxia in this population of exquisitely vulnerable infants has been associated with reduced morbidity, including retinopathy of prematurity, chronic lung disease, and brain injury. Two populations of interest were identified: VPIs receiving supplemental oxygen and NICU clinicians. Interventions were employed to (1) improve knowledge regarding hyperoxia and associated outcome sequelae in an interdisciplinary sample of clinicians (pretest posttest design) and (2) reinforce content of the educational intervention by triggering caregiver behaviors to reduce time the VPIs is above target SpO2 range while receiving supplemental oxygen (cohort design). : Retrospective chart review, baseline clinician knowledge assessment, education, posteducation assessment, collaborative rounds with regular feedback citing time VPIs spent above target oxygen saturation levels (SpO2), and evaluation of impact on time infants spent above target SpO2 range aligned with the project purpose. Pre- and postintervention dependent variables included clinician knowledge of hyperoxia and related evidence as measured by a 24-item multiple-choice Knowledge Assessment Tool before and after attending an educational presentation. Time VPIs were exposed to hyperoxia was evaluated using SpO2 readings and calculating the percentage of time readings were above target range before and after the introduction of educational and behavioral interventions. Outcome 1 was to increase knowledge about hyperoxia among clinician caregivers. Paired-samples t test showed a significant difference between preintervention and postintervention Knowledge Assessment Tool scores (P = .000). Outcome 2 measured reduction in time spent with SpO2 readings above target range. An independent-samples t test was used to compare outcomes in preintervention and postintervention VPI cohorts. Mean time spent with SpO2 greater than target range increased in the postintervention cohort, reaching statistical significance with P = .047. Knowledge acquisition on the subject of hyperoxia in VPIs was achieved. Decreasing the percent time VPIs were exposed to hyperoxia was not attained. The postintervention VPI cohort spent more time above the target saturation range despite greater knowledge among clinicians.

Hyperoxia in Very Preterm Infants

Supplemental oxygen plays a critical role in the management of infants born at the lower limit of viability, but not without the risk of complications resulting from high levels or prolonged exposure. Longitudinal studies of very premature infants, born at less than 28 weeks' gestation, establish a clear relationship between pulse oximetry saturation readings above 92%, or hyperoxia, and development of severe retinopathy of prematurity, chronic lung disease, and brain injury. Hyperoxia is neither natural nor random. It is an unintended consequence of intervention. A comprehensive review of the literature reveals a strong association between exposure to hyperoxia and subsequent expression of comorbidities. Owing to this knowledge, eradication of hyperoxia, and consequent reduction of sequelae, is a significant public health concern that deserves attention by the neonatal community. Although prospective, collaborative meta-analyses will soon provide needed additional data to inform practice, existing compelling evidence supports urgent practice change to reduce exposure to hyperoxia in very preterm infants.

Early adult outcomes following delivery at 23–26 weeks of gestation

Objective. There are few reports of young adult outcomes of infants born at 23-26 weeks gestation. The objective of this study is to report educational, health, social, and employment outcomes of a large cohort of these infants born during an era when significant advances in neonatal care led to a marked increase in survival. Methods. Medical records of 316 infants who were born between January 1, 1986 and December 31, 1990, were analyzed retrospectively. Two hundred three (64%) infants survived to discharge home, and 5 died following discharge, leaving 198 young adults available for follow-up. One hundred sixty-two (82%) young adults responded to a 27 item telephone questionnaire designed to assess educational, health, social, and employment status at a mean age of 19.3 years. Parents of subjects were interviewed in cases where subjects could not be contacted or had cognitive issues which precluded their responding (19 subjects). Parent social and educational status was previously obtained by response to a phone survey at eight year follow-up and also by phone interview of parents of young adults previously not available for follow-up, but who were located for this report. Results. The only statistically significant differences between the 162 young adult responders and the 36 non-responders were a younger maternal age at delivery (28 ± 6 years vs 25 ± 6 years, respectively, p = 0.015) and race (91% of responders were white compared to 67% of the non-responders, p = 0.001). One hundred forty-three (88%) young adults had graduated from high school. Eighty-four (52%) required educational assistance in the form of special education, a tutor, or an Individual Education Plan (IEP). Ninety-one (56%) were currently enrolled in post-secondary education. These levels of educational achievement closely correspond to the 91% of their mothers who graduated from high school and the 57% who had completed some college level courses, including 30% with either four-year or advanced degrees. Twenty-nine (18%) of the young adults interviewed reported some problems with depression. Thirty subjects admitted to using alcohol socially, 11 reported tobacco use, and 3 admitted to using marijuana. One hundred forty-two have been or are currently employed. Conclusions. The majority of infants born at the lower limits of viability not only have the potential to survive, but with appropriate assistance and resources have the ability to successfully navigate the educational system and eventually be employed as productive members of society.

Obstetric interventions for babies born before 28 weeks of gestation in Europe: results of the MOSAIC study

To describe obstetric intervention for extremely preterm births in ten European regions and assess its impact on mortality and short term morbidity. Prospective observational cohort study. Ten regions from nine countries participating in the 'Models of Organising Access to Intensive Care for Very Preterm Babies in Europe' (MOSAIC) project. All births from 22 to 29 weeks of gestation (n = 4146) in 2003, excluding terminations of pregnancy. Comparison of three obstetric interventions (antenatal corticosteroids, antenatal transfer and caesarean section for fetal indication) rates at 22-23, 24-25 and 26-27 weeks to that at 28-29 weeks and the association of the level of intervention with pregnancy outcome. Use of antenatal corticosteroids, antenatal transfer and caesarean section by two-week gestational age groups as well as a composite score of these three interventions. Outcomes included stillbirth, in-hospital mortality and intraventricular haemorrhage (IVH) grades III and IV and/or periventricular leucomalacia (PVL) and bronchopulmonary dysplasia (BPD). There were large differences between regions in interventions for births at 22-23 and 24-25 weeks. Differences were most pronounced at 24-25 weeks; in some regions these babies received the same care as babies of 28-29 weeks, whereas elsewhere levels of intervention were distinctly lower. Before 26 weeks and especially at 24-25 weeks, there was an association between the composite intervention score and mortality. No association was observed at 26-27 weeks. For survivors at 24-25 weeks, the intervention score was associated with higher rates of BPD, but not with IVH or PVL. There are large differences between European regions in obstetric practices at the lower limit of viability and these are related to outcome, especially at 24-25 weeks.

Guidelines for Care of Fetal Infants at the Limit of Viability

Viability of the fetal infant is its capability of living. It usually implies a fetus that has reached 500g in weight and 20 gestational weeks. Lower limit of viability is between 23 and 25 weeks’ gestation in developed countries at present. Trends toward intervention at an earlier gestational age may be continuing. However, the term of viability does not simply mean the ability to be born alive, but the capability to grow and to develop normally in the extrauterine environment. There are concerns on what is the best management for fetal infants on the edge of viability. Decisions regarding all aspects of management of the birth and subsequent care of the fetal infant should be based on the fetal and infant’s condition and prognosis and be made jointly by the parents and the physicians. This article will discuss medical, legal, socioeconomic and ethical issues to find the best way in the management of the fetal infants.

School-Age Consequences of Birth Weight Less Than 750 g: A Review and Update

Recent advances in perinatal care have led to the survival of increasing numbers of children born at the lower limits of viability. Children with very low birth weight (LBW; less than 1,500 g, 3 lb 5 oz) have been studied extensively. Findings document poorer outcomes relative to normal birth weight term-born controls in neurologic and health status, cognitive-neuropsychological skills, school performance, academic achievement, and behavior. This report reviews current knowledge regarding LBW children, with special emphasis on outcomes for children with birth weight less than 750 g (1 lb 10 oz). Results from an ongoing longitudinal study suggest a gradient of sequelae, with poorer outcomes in less than 750 g birth weight children compared to both 750 g to 1,499 g birth weight children and term-born controls. Children with less than 750 g birth weight fail to catch up with their peers over time and may even be at risk for age-related increases in sequelae. Outcomes are highly variable but related to neonatal medical complications of prematurity and social risk factors. Further research is needed to understand the etiology and neuropathological basis of sequelae, the long-term developmental implications of LBW, and treatment needs.

Parental voices in the sea of neonatal ethical dilemmas.

Ethical debate in neonatal intensive care centers around the lower limits of viability, the use of multiple invasive procedures, and the role of paternalism. The parents' perspective has been addressed infrequently. This report will focus on the parents' statements as obtained through predischarge in-depth interviews with 32 families, each with a high-risk infant(s). Discussion will include a summary of the range of parental perceptions during two major periods of time: preadmission to the NICU and the NICU experience itself. Some possible nursing implications will be drawn that reflect a sensitive response to these parental perceptions.

An Epidemiologic Study of Very Low and Very Very Low Birth Weight Infants

VVLBW infants constitute only 1 per cent of the total births, but account for 60 per cent of the NMR and 40 per cent of the IMR. While improved technology and refinements in care continue to improve survival for VVLBW infants, questions regarding the lower limits of viability must be considered. The medical community can rightly take credit for improvement in outcome of infants with weight and gestations so small that, just a decade ago, they were considered nonviable; however, an excruciatingly slow pace of decline in the prematurity rate is an agonizing fact. Can anything be done to prevent prematurity and avoid its devastating consequences on the family and society? The recent French experience suggests the answer could be "yes." A similar experience also has been reported in the United States. Although VLBW NMR is a major fraction of total IMR, nearly one quarter of first-year deaths occur in infants who are over 2500 gm at birth. That the postneonatal death of normal birth weight infants is only next in magnitude to the neonatal death of VLBW infants further points to the need for developing preventive child health programs encompassing periods before and during the pregnancy, through the immediate peripartum period, and well into infancy and childhood. Neither a woman's pregnancy experience nor the concerns of the health community end with her taking a baby home.

Changes in the delivery room care of the extremely small infant (less than 750 g). Effects on morbidity and outcome.

Advances in perinatal care have been accompanied by improved survival among infants born in the middle to late second trimester, who were previously considered nonviable. This development has led to the spurious assumption that life can be sustained in live-born infants irrespective of gestational age or birth weight. Since pessimism prevails in the few reports on later outcomes among these very small and immature infants, the indiscriminate initiation of intensive care raises many philosophical, ethical, and economic questions.1 2 3 4 5 6 7 8 9 10 Despite many reviews with titles such as How Small Is Too Small?,11 What Is the Lower Limit of Viability?,12 and Where and . . .

REDUCTION OF MORTALITY FROM PREMATURE BIRTH

The purpose of this paper is to present our concept of certain problems of prematurity and to discuss the practical measures instituted at the Long Island College Hospital to improve our results in this field. We consider a premature infant to be any infant born alive who weighs 2,500 Gm. (5 pounds, 8 ounces) or less, whose heart beats or who moves. No lower limit of viability is allowed. This definition is that which is accepted by the American Academy of Pediatrics1and must be rigidly adhered to by all institutions and agencies for reports and tabulations if experiences are to be comparable. That prematurity is a leading cause of death in the United States has recently been reemphasized by the United States Children's Bureau (Dunham2) in an analysis based on reports of the United States Bureau of Census for the year 1944 (the most recent year in

A PREMATURE INFANT WEIGHING 735 GRAMS AND SURVIVING

A review of the literature reveals that few infants weighing less than 1,000 Gm. at birth survive. Ylppo 1 states that the lower limit of viability is about 800 Gm. The smallest infant for which a complete report appears in the literature is that reported by Helene Fischer-Ban. 2 This infant weighed 600 Gm. at birth and 540 Gm. after three days. She regained her birth weight in ten days and at the time of the report was 3 years old, small but otherwise normal. Pulford and Blevins 3 report a six month premature infant weighing 680 Gm.; the child was over 2 years old when the report was made. Houlihan 4 described a case of a six and one-half month premature infant weighing 705 Gm. This case was especially interesting in that no human milk was available, so that the child was artificially fed from birth and kept in