The definition of human viability: a historical perspective

Aim:  To investigate the current concepts related to the definition of human viability in a historical perspective.
Methods:  A review of the international literature was performed by using PubMed, Google, Embase to find definitions of Human Viability. The papers collected were divided chronologically.
Results:  Over the years, many authors have debated the concept of the limit of human viability, starting from Ballantyne in the early 1900. The definition differs from author to author.
Conclusion:  The definition of human viability is still under discussion. It depends primarily, but not only, on gestational age. A number of genetic, cultural, social and technological variables are also influential. This definition could have an impact on legislation and the widespread misunderstanding of this concept in the lay public could also be enhanced by a frank discussion among clinicians and other professionals.     

Resuscitation at birth

It is only in recent years that the techniques used for resuscitation at birth have come under critical review and there have been very few controlled trials to assess their efficacy. Recent studies have indicated that the large majority of asphyxiated term babies can be resuscitated using air rather than 100% oxygen, possibly reducing damage from oxygen free radicals during re-perfusion. Physiological studies have shown that inflation pressures of 25–30 cmH₂O maintained for up to 1 s, only result in approximately 40% of the mean inspiratory volume achieved by babies who breathed spontaneously at birth. These spontaneous inflation volumes can be matched either by maintaining the first inflation for 3 s, or by using pressures of up to 50 cmH₂O for 300 ms, a pattern adopted by spontaneously breathing babies. Bag and mask systems are even less effective, often depending on the Head paradoxical reflex to stimulate respiration rather than producing adequate tidal exchange. Face mask T-piece devices provide more effective ventilatory exchange and are easier to use. Conclusion Although the pattern of ventilatory support in current use often leads to successful resuscitation of asphyxiated babies at birth, more physiological and randomised controlled studies are needed to refine techniques in order to limit babies' exposure to potentially damaging hypoxia to the minimum. Received: 19 January 1998 / Accepted: 19 January 1998     

Life and death decisions for incompetent patients: determining best interests--the Irish perspective

Aims: To determine whether healthcare providers apply the best interest principle equally to different resuscitation decisions. Methods: An anonymous questionnaire was distributed to consultants, trainees in neonatology, paediatrics, obstetrics and 4th medical students. It examined resuscitation scenarios of critically ill patients all needing immediate resuscitation. Outcomes were described including survival and potential long‐term sequelae. Respondents were asked whether they would intubate, whether resuscitation was in the patients best interest, would they accept surrogate refusal to initiate resuscitation and in what order they would resuscitate. Results: The response rate was 74%. The majority would wish resuscitation for all except the 80‐year‐old. It was in the best interest of the 2‐month‐old and the 7‐year‐old to be resuscitated compared to the remaining scenarios (p value <0.05 for each comparison). Approximately one quarter who believed it was in a patient best interests to be resuscitated would nonetheless accept the family refusing resuscitation. Medical students were statistically more likely to advocate resuscitation in each category. Conclusion: These results suggest resuscitation is not solely related to survival or long‐term outcome and the best interest principle is applied differently, more so at the beginning of life.     

Ocular complications at the limits of viability

AIM: To evaluate the incidence of retinopathy of prematurity (ROP) and other ocular morbidities in extremely premature infants. METHODS: A retrospective analysis of the prevalence and nature of ocular abnormalities in a cohort of 22 extremely pre-term infants born <25 + 0 weeks of estimated gestational age (GA) was performed. RESULTS: The children were grouped according to the observed disorder: 13 out of 22 (59%) neonates with mild ophthalmologic findings (ROP < or = stage II) [Group 1], 5 out of 22 (23%) infants with ROP stage III or more (Group 2) and 4 out of 22 (18%) neonates with severe ocular morbidity (congenital cataract, microphthalmia, partial optic nerve atrophy and corneal perforation due to an ulcer with lens protrusion), partly combined with ROP > or = stage III (three of four). One child of 22 (5%) needed laser therapy. Out of 22 admitted infants, 20 (91%) were discharged alive. CONCLUSION: The high rate of ocular morbidity besides ROP in extremely pre-term infants is noteworthy. Mechanisms influencing the postnatal development of the eye, especially their relation to the grade of prematurity and neonatological therapeutical strategies, require further investigations.     

Resuscitation of the depressed newborn

The resuscitation of babies at birth is different from the resuscitation of all other age groups, and knowledge of the relevant physiology and pathophysiology is essential. Although the majority of babies will establish normal respiration and circulation without help after delivery, those babies who do not establish adequate regular normal breathing, or who have a heart rate of less than 100 beats per minute, require assistance. Despite the limitation of the available evidence, an international body of experts has provided guidelines for neonatal resuscitation.     

Resuscitation of the Newborn

ABSTRACT. During cardiopulmonary resuscitation, when an intravenous line is not present or easily obtainable, the intracardiac injection of drugs has been a traditional route of choice. However, the intracardiac administration may be associated with serious complications. We have given epinephrine endotracheally to ten newborn infants who all had bradycardia that did not respond to ventilation with 100 % oxygen, to heart compression or to bicarbonate infusion. Epinephrine, 0.1 mg/ml was injected directly into the tracheal tube, and ventilation was immediately continued. A standardized procedure has been chosen by giving 0.25 ml to the infants weighing < 1500 g, 0.5 ml to those weighing between 1500 and 2500 g, and 1.0 ml to those >2500 g. All infants had a return to normal heart rhythm within seconds after installation of the epinephrine solution. The establishment of an intravenous line in small infants can be difficult, and the infants are usually intubated before the injection of epinephrine is considered. The endotracheal route should therefore be the first route of choice in the absence of a rapidly obtainable vascular access.     

Improved outcome for infants at the limits of viability

Factors associated with survival and freedom from cerebral parenchymal lesions and severe retinopathy were examined in a cohort of 250 extremely preterm infants of less than 26 weeks gestation admitted to a regional neonatal intensive care unit between 1982 and 1993. There were 99 survivors of whom 73 were free of major early morbidity.     

33家医院新生儿复苏前状态的初步调查

目的了解当前各级医院新生儿窒息复苏前准备状态。方法对33家医院进行问卷式调查。结果①复苏器具：大数数具备电动吸引器、吸痰管、复苏囊、新生儿喉镜、气管插管、氧气，保暖设施；但有的器具准备不全；②复苏药品：均备有肾上腺素和碳酸氢钠，但94％同时又备有一些错误药品；③复苏方法：仅14家方法全对(42．4％)，仍有采用旧法复苏；④紧急复苏步骤：能全部选用正确方法的不到一半(48．5％)；⑤窒息判断标准：88％的医生能以Apgar评分作为判断标准；⑥培训情况：仅36．4％的医生参加过正规培训；⑦产儿科合作情况：36．4％的医院儿科医生不进产房，剖宫产时到场的就更少(18．8％)。结论当前各级医院新生儿窒息复苏前准备状态不容乐观，需要进一步加强复苏器具和药品的正确准备，加强新法复苏培训，加强产科与儿科合作。     

The transition from fetus to neonate – an endocrine perspective

Gluckman PD, Sizonenko SV, Bassett NS. The transition from fetus to neonate - an endocrine perspective. Acta Pædiatr 1999; Suppl 428: 7–11. Stockholm. ISSN 0803–5326
The transition from fetus to neonate involves three phases: late gestation, parturition and the processes needed to establish independent homoeostatic regulation after separation from the placenta. These phases are regulated by a series of fetal and placental endocrine events. Glucocorticoids have an important role in the preparation for birth, including involvement in lung and cardiac development, and the maturation of enzymes in a variety of pathways. Fetal Cortisol production is, in turn, also under hormonal control. Parturition is a complex process, which is still poorly understood in humans. The final steps are largely dependent on the effect of prostaglandin F_2α on the myometrium associated with increased oxytocin activity. The transition to birth is accompanied by changes in respiration, circulation, glucose homoeostasis, and the onset of independent oral feeding and thermoregulation. Several examples of endocrine components of the transition from fetal to neonatal life are reviewed here: the role of prostanoids, the onset of thermogenesis, and changes in the thyroid hormone and growth hormone axes. The effects of hormone levels on prematurity and growth retardation are also discussed. □ Birth transition, fetus, gestation, hormonal control, neonate, parturition     

Babies born at the threshold of viability: attitudes of paediatric consultants and trainees in South East England

Aim: To determine attitudes of paediatric consultants and trainees towards immediate care of babies born at 22–24 weeks gestation. Methods: A questionnaire was sent to one consultant and one trainee within each of 63 neonatal units in South East England. Results: Response rate was 90% (111/123). At 22 weeks gestation, 51% of all respondents would not attend the delivery. At 23 weeks gestation, 63% of respondents would advise against resuscitation during antenatal counselling but 45% would resuscitate despite a parental request for comfort care. Forty‐one percent of respondents would provide comfort care for a 23 week gestation baby born in poor condition. If required, 53% of respondents would use chest compressions and/or adrenaline at birth of a 24 week gestation infant (38% consultants, 54% trainees; p = 0.05). More experienced and older paediatricians were more likely to attend 22 week deliveries and be comfortable with parental requests for resuscitation. Fifty‐four percent of units had written guidelines on care of these babies. Significantly more consultants (67%) than trainees (25%) correctly classified neonatal deaths. Conclusions: Paediatricians with greater experience and age demonstrated more shared decision‐making with parents. Nearly half of paediatricians would defy parental wishes at 23 weeks gestation, contrary to ethical recommendations (Nuffield Council on Bioethics, http://www.nuffieldbioethics.org ).     

Single-centre vs. population-based outcome data of extremely preterm infants at the limits of viability

Aim:  In response to the disappointing outcome data of the population-based EPICure study published in 2000, we compared the outcome of infants 22 0/7 to 25 6/7 weeks of gestational age (GA) in a single tertiary care centre 2000–2004 with that of EPICure.
Methods:  EPICure tools and definitions, including 30 months' Bayley Scales.
Results:  Of 83 infants <26 weeks born alive, more were admitted to intensive care – 82% vs. 68% (p  <  0.0001) – and more infants survived to discharge (57% vs. 26%, p <   0.0001; 69% vs. 39%, p  <  0.01, of those admitted to intensive care). More infants, as a percentage of live births, survived without severe (41%, 34/83 vs. 20%, 233/1185, p <   0.0001) or overall disability (22%, 18/83 vs. 13%, 155/1185, p  =  0.03). However, at the border of viability – GA 23 and 24 weeks – the rate of infants surviving without overall disability was not significantly higher (13%, 6/45 vs. 9%, 56/623).
Conclusion:  In infants <26 weeks of GA, increased rates of survival and survival without disability were observed in a single-centre inborn cohort born 5–8 years later than the EPICure cohort. This did not translate into increased survival without overall disability in infants of 23–24 weeks of GA.     

Ethical implications of the use of decision aids for antenatal counseling at the limits of gestational viability

Shared decision-making is a recent priority in neonatology. However, its implementation is at an early stage. Decision aids are tools designed to assist in shared decision-making. They help patients competently participate in making healthcare decisions. There are limited studies in neonatology on the formal use of decision aids as used in adult medicine. Decision aids are relatively new, even in adult medicine where they were pioneered; therefore, there is a lack of systematic oversight to their development and use. Despite evidence reporting a powerful effect on patients' decisions, decision aids are not subject to quality control, leading to potentially enormous ethical implications. These include: (i) possible introduction of developers' biases; (ii) use of outdated or incorrect information; (iii) misuse to steer a patient towards less expensive treatments; (iv) clinician liability if negative patient outcomes occur, since decision aids are currently not standard of care.     

Predictive value of the 1‐min Apgar score for survival at 23–26 weeks gestational age

Aim: Is a 1‐min Apgar score ≤1 predictive of mortality in resuscitated extremely premature infants? Methods: A retrospective case–control review of all infants with gestational ages <27 weeks over a 5‐year period. All values as median [75% CI]. Results: Of 237 infants, 29 had 1‐min Apgar scores ≤1 (Group 1) and 208 had scores >1 (Group 2). Despite earlier and more frequent intubation (2 min [2.3; 6.7] vs. 5 min [7.5; 10] and 93% vs. 77%, p = 0.04), mortality was higher in Group 1 (62% vs. 17%; p < 0.0001). Age at death did not differ (Group 1: 3.5 days [1; 30] vs. Group 2: 6 days [6; 44]). Birth weight and sex were the best predictors of survival. With a 1‐min Apgar score of 1, a male infant at 23 weeks and 500 g had a mortality rate of 92%. Conclusion: Despite successful resuscitation, infants between 23 and 26 weeks have a very poor prognosis for survival when presenting with bradycardia, cyanosis and no respiratory efforts (1‐min Apgar = 1) at birth. According to our data, initiating active treatment for an infant at 23 weeks with bradycardia and apnoea is almost always unsuccessful, whereas by 26 weeks gestation, the chance of survival is higher than the probability of death.