Limits of viability: definition of the gray zone

Abstract

Introduction: As survival and long-term morbidity of very preterm infants have improved over the past decade, the limits of infant viability, the level of maturity below which survival and/or acceptable neurodevelopmental outcome are extremely unlikely, have also decreased. Study Design:In an effort to define the current limits of infant viability, the data in the literature on survival and long-term neurodevelopmental outcome in very preterm neonates have been reviewed. Result:The gestational age and birth weight below which infants are too immature to survive, and thus provision of intensive care is unreasonable, appears to be at <23 weeks and <500 g, respectively. Infants born at X25 weeks' gestation and with a birth weight of X600 g are mature enough to warrant initiation of intensive care, as the majority of these patients survive, and at least 50% do so without severe long-term disabilities. Finally, for infants born between 23 0/7 and 24 6/7 weeks' gestation and with a birth weight of 500 to 599 g, survival and outcome are extremely uncertain. For these infants born in the so-called 'gray zone' of infant viability, the line between patient autonomy and medical futility is blurred, and medical decision-making becomes even more complex and needs to embrace careful consideration of several factors. These factors include appraisal of prenatal data and the information obtained during consultations with the parents before delivery; evaluation of the patient's gestational age, birth weight and clinical condition upon delivery; ongoing reassessment of the patient's response to resuscitation and intensive care and continued involvement of the parents in the decision-making process after delivery.Conclusion: Based on these findings an algorithm is offered for consideration for neonatologists managing infants born in the 'gray zone' of infant viability. However, caution must be exercised when one considers incorporating this guideline into clinical practice because the algorithm is based on the analysis of the findings in the literature and the authors' experience rather than direct evidence.

Doppler Flow Velocity Indices (RI, PI, S/D & PSV) of Fetal Middle Cerebral Artery in Normal Pregnancies: Correlation with Gestational Age of 20 to 40 Weeks

“…This age distribution reflects the age related fertility of the study subjects. Considering the age of viability as 25 weeks 5 the Doppler indices observations are categorized in two groups (less than 25 weeks groups and more than 25. weeks). Regarding PSV it was seen that mean (±SD) PSV was 32.17 (±7.98) cm/sec.…”

Ética na decisão terapêutica em condições de prematuridade extrema

“…Diversas publicações apresentam resultados claros e consistentes a respeito da decisão de parturientes e gestantes, a partir do processo de aconselhamento em situações envolvendo risco de morte dos bebês, e ao mesmo tempo compartilham recomendações específicas quanto a intervenção médica em casos de prematuridade extrema [1][2][3] . Percebe-se que os índices de morbidade, aos poucos, têm substituído os de mortalidade em bebês prematuros nos diferentes limites de viabilidade 4 . Embora tenha sido observado significativo declínio da mortalidade dos nascidos vivos em extremos de prematuridade, a taxa de injúria neuroevolutiva permanece alta [5][6][7][8] .…”

Second trimester abortion laws globally: actuality, trends and recommendations

“…10 In any case, there is no scientific support for such changes. 28,32 One of the few bodies that examined the evidence in detail, the UK Parliament's Science and Technology Committee, concluded in 2007 that there was no justification for lowering the legal time limit on abortion. 29 …”

“…Many laws do not establish time limits, no matter what the indication, while others specify (sometimes different) time limits for certain indications, but not for others. In other laws, a time limit must be inferred from the requirement that an abortion must be carried out before "viability", a term that is about the chances of preterm survival in relation to wanted pregnancies and has no one accepted definition, [28][29][30][31][32] and arguably no relevance in relation to induced abortion. This paper therefore includes the term as it appears in specific laws, but without seeking to assign a specific meaning to it.…”