Oxygen for newborn resuscitation: how much is enough?

Monitoring SpO2: The Basics of Retinopathy of Prematurity (Back to Basics) and Targeting Oxygen Saturation

Oxygen (O2) is a drug frequently used in newborn care. Adverse effects of hypoxia are well known but the damaging effects of excess oxygen administration and oxidative stress have only been studied in the last 2 decades. Many negative effects have been described, including retinopathy of prematurity . Noninvasive pulse oximetry (SpO2) is useful to detect hypoxemia but requires careful evaluation and understanding of the frequently changing relationship between O2 and hemoglobin to prevent hyperoxemia. Intention to treat SpO2 ranges should be individualized for every newborn receiving supplemental O2, according to gestational age, post-natal age, and clinical condition.

Higher versus Lower Oxygen Concentration during Respiratory Support in the Delivery Room in Extremely Preterm Infants: A Pilot Feasibility Study

Background: Optimal starting oxygen concentration for delivery room resuscitation of extremely preterm infants (<29 weeks) remains unknown, with recommendations of 21–30% based on uncertain evidence. Individual patient randomized trials designed to answer this question have been hampered by poor enrolment. Hypothesis: It is feasible to compare 30% vs. 60% starting oxygen for delivery room resuscitation of extremely preterm infants using a change in local hospital policy and deferred consent approach. Study design: Prospective, single-center, feasibility study, with each starting oxygen concentration used for two months for all eligible infants. Population: Infants born at 23 + 0–28 + 6 weeks’ gestation who received delivery room resuscitation. Study interventions: Initial oxygen at 30% or 60%, increasing by 10–20% every minute for heart rate < 100 bpm, or increase to 100% for chest compressions. Primary outcome: Feasibility, defined by (i) achieving difference in cumulative supplied oxygen concentration between groups, and (ii) post-intervention rate consent >50%. Results: Thirty-four infants were born during a 4-month period; consent was obtained in 63%. Thirty (n = 12, 30% group; n = 18, 60% group) were analyzed, including limited data from eight who died or were transferred before parents could be approached. Median cumulative oxygen concentrations were significantly different between the two groups in the first 5 min. Conclusion: Randomized control trial of 30% or 60% oxygen at the initiation of resuscitation of extremely preterm neonates with deferred consent is feasible. Trial registration: Clinicaltrials.gov NCT03706586

Monitoring oxygen saturation and heart rate during neonatal transition. comparison between two different pulse oximeters and electrocardiography

OBJECTIVE

To compare the efficacy and reliability of two pulse-oximeters (POx) (Masimo Radical-7 and Nellcor^™ Oxymax Bedside) and evaluate the feasibility of routine ECG monitoring during delivery room transition.

STUDY DESIGN

Prospective observational comparative study. Sixty newborns were connected simultaneously to both POxs and ECG monitor (as a gold standard for HR). Times to achieve a stable signal were compared. Heart rates were compared to simultaneous ECG.

RESULTS

A significant difference in times to stable signal was found: Mean, Median (Interquartile range) for Nellcor and Masimo, were 15, 8.5 (6-18) and 27, 12 (9-34) seconds, respectively. Compared to ECG, false bradycardia was displayed in 18 of 55 (35%) newborns by the Masimo POx and in no newborns by the Nellcor POx. Attaching the ECG monitor was feasible but consumed additional resources.

CONCLUSIONS

The time for achievement of a stable saturation reading in an uncomplicated resuscitation setting differed significantly between POxs.

Oxygen Therapy for Neonatal Resuscitation in the Delivery Room

Oxygen is commonly used in the delivery room during neonatal resuscitation. The transition from intrauterine to extrauterine life is a challenge to newborns, and exposure to too much oxygen can cause an increase in oxidative stress. The goal of resuscitation is to achieve normal oxygen levels as quickly as possible while avoiding excessive oxygen exposure and preventing inadequate oxygen supplementation. Although it has been shown that room air resuscitation is as effective as using 100% oxygen, often preterm infants need some degree of oxygen supplementation. The ideal concentration of oxygen with which to initiate resuscitation is yet to be determined. Current delivery room resuscitation guidelines recommend the use of room air for term newborns and preterm newborns of greater than or equal to 35 weeks' gestation and the use of a fraction of inspired oxygen of 0.21 to 0.3 for preterm infants of less than 35 weeks' gestation. Further recommendations include titrating oxygen supplementation as needed to obtain goal saturations. However, there is no current consensus on an intermediate oxygen concentration to start resuscitation or goal range saturations for preterm and asphyxiated term infants.

A Review of Oxygen Use During Chest Compressions in Newborns-A Meta-Analysis of Animal Data

Background: International consensus statements for resuscitation of newborn infants recommend provision of 100% oxygen once chest compressions are required. However, 100% oxygen exacerbates reperfusion injury and reduces cerebral perfusion in newborn babies. Objective: We aimed to establish whether resuscitation with air during chest compression is feasible and safe in newborn infants compared with 100% oxygen. Methods: Systematic search of PubMed, Google Scholar and CINAHL for articles examining variable oxygen concentrations during chest compressions in term newborns. Results: Overall, no human studies but eight animal studies (n = 323 animals) comparing various oxygen concentrations during chest compression were identified. The pooled analysis showed no difference in mortality rates for animals resuscitated with air vs. 100% oxygen (risk ratio 1.04 [0.35, 3.08], I² = 0%, p = 0.94). ROSC was also similar between groups with a mean difference of -3.8 [-29.7-22] s, I² = 0%, p = 0.77. No difference in oxygen damage or adverse events were identified between groups. Conclusions: Air had similar time to ROSC and mortality as 100% oxygen during neonatal chest compression. A large randomized controlled clinical trial comparing air vs. 100% oxygen during neonatal chest compression is warranted.

Bench-to-bedside review: the effects of hyperoxia during critical illness

Oxygen administration is uniformly used in emergency and intensive care medicine and has life-saving potential in critical conditions. However, excessive oxygenation also has deleterious properties in various pathophysiological processes and consequently both clinical and translational studies investigating hyperoxia during critical illness have gained increasing interest. Reactive oxygen species are notorious by-products of hyperoxia and play a pivotal role in cell signaling pathways. The effects are diverse, but when the homeostatic balance is disturbed, reactive oxygen species typically conserve a vicious cycle of tissue injury, characterized by cell damage, cell death, and inflammation. The most prominent symptoms in the abundantly exposed lungs include tracheobronchitis, pulmonary edema, and respiratory failure. In addition, absorptive atelectasis results as a physiological phenomenon with increasing levels of inspiratory oxygen. Hyperoxia-induced vasoconstriction can be beneficial during vasodilatory shock, but hemodynamic changes may also impose risk when organ perfusion is impaired. In this context, oxygen may be recognized as a multifaceted agent, a modifiable risk factor, and a feasible target for intervention. Although most clinical outcomes are still under extensive investigation, careful titration of oxygen supply is warranted in order to secure adequate tissue oxygenation while preventing hyperoxic harm.

Pulse oximetry in very low birth weight infants

Pulse oximetry has become ubiquitous and is used routinely during neonatal care. Emerging evidence highlights the continued uncertainty regarding definition of the optimal range to target pulse oximetry oxygen saturation levels in very low birth weight infants. Furthermore, maintaining optimal oxygen saturation targets is a demanding and tedious task because of the frequency with which oxygenation changes, especially in these small infants receiving prolonged respiratory support. This article addresses the historical perspective, basic physiologic principles behind pulse oximetry operation, and the use of pulse oximetry in targeting different oxygen ranges at various time-points throughout the neonatal period.

Born too soon: care for the preterm baby

As part of a supplement entitled “Born Too Soon”, this paper focuses on care of the preterm newborn. An estimated 15 million babies are born preterm, and the survival gap between those born in high and low income countries is widening, with one million deaths a year due to direct complications of preterm birth, and around one million more where preterm birth is a risk factor, especially amongst those who are also growth restricted. Most premature babies (>80%) are between 32 and 37 weeks of gestation, and many die needlessly for lack of simple care. We outline a series of packages of care that build on essential care for every newborn comprising support for immediate and exclusive breastfeeding, thermal care, and hygienic cord and skin care. For babies who do not breathe at birth, rapid neonatal resuscitation is crucial. Extra care for small babies, including Kangaroo Mother Care, and feeding support, can halve mortality in babies weighing <2000 g. Case management of newborns with signs of infection, safe oxygen management and supportive care for those with respiratory complications, and care for those with significant jaundice are all critical, and are especially dependent on competent nursing care. Neonatal intensive care units in high income settings are de-intensifying care, for example increasing use of continuous positive airway pressure (CPAP) and this makes comprehensive preterm care more transferable. For health systems in low and middle income settings with increasing facility births, district hospitals are the key frontier for improving obstetric and neonatal care, and some large scale programmes now include specific newborn care strategies. However there are still around 50 million births outside facilities, hence home visits for mothers and newborns, as well as women’s groups are crucial for reaching these families, often the poorest. A fundamental challenge is improving programmatic tracking data for coverage and quality, and measuring disability-free survival. The power of parent’s voices has been important in high-income countries in bringing attention to preterm newborns, but is still missing from the most affected countries.

Cardiopulmonary resuscitation with chest compressions during sustained inflations: a new technique of neonatal resuscitation that improves recovery and survival in a neonatal porcine model

BACKGROUND

Guidelines on neonatal resuscitation recommend 90 chest compressions (CCs) and 30 manual inflations (3:1) per minute in newborns. The study aimed to determine whether CC s during sustained inflations (SIs) improves the recovery of asphyxiated newborn piglets in comparison with coordinated 3:1 resuscitation.

METHODS AND RESULTS

Term newborn piglets (n=8/group) were anesthetized, intubated, instrumented, and exposed to 45-minute normocapnic hypoxia followed by asphyxia. Piglets were randomly assigned to receive either 3:1 resuscitation (3:1 group) or CCs during SIs (SI group) when the heart rate decreased to 25% of baseline. Piglets randomly assigned to the SI group received SIs with a pressure of 30 cm H2O for 30 s. During the SI, CCs at a rate of 120/min were provided. SI was interrupted after 30 s for 1 s before a further 30-s SI was provided. CCs were continued throughout SIs. CCs and SI were continued until the return of spontaneous circulation. Continuous respiratory parameters, cardiac output, mean systemic and pulmonary artery pressures, and regional blood flows were measured. Mean (standard deviation) time for return of spontaneous circulation was significantly reduced in SI group versus 3:1 group (32 [11] s versus 205 [113] s, respectively). In the SI group, administration of oxygen and epinephrine was significantly lower, whereas minute ventilation and exhaled CO2 were significantly increased. The SI group had significantly higher mean systemic and pulmonary arterial pressures during resuscitation in comparison with the 3:1 group (51 [10] versus 31 [5] mm Hg; 41[7] versus 31 [7] mm Hg, respectively; all P<0.05), with improved cardiac output and carotid blood flow.

CONCLUSIONS

Combining CCs and SIs significantly improved the return of spontaneous circulation with better hemodynamic recovery in asphyxiated newborn piglets in comparison with standard coordinated 3:1 resuscitation.

Understanding the effects of oxygen administration in haemorrhagic shock

AIMS AND OBJECTIVES

the aim of this article is to provide a review of the literature regarding oxygen administration and the use of oxygen in patients experiencing haemorrhagic shock (HS).

RESULTS

oxygen is administered to patients to assist them in maintaining oxygenation. The administration of oxygen is complex and varies significantly among patients. In order to optimize patient care, clinicians need to be aware of the potential effects, both beneficial and harmful, that oxygen can have on the body.

INCLUSION AND EXCLUSION CRITERIA

literature inclusion criteria for this article was any article (1995 to present) pertaining to oxygen administration and HS. Also included were articles related to tissue injury caused by an overabundance of free radicals with the administration of oxygen. Articles related to oxygen and wound healing, pollution, aerospace, food and industrial uses were excluded.

CONCLUSIONS

this review of the literature provides an overview of the use of oxygen in clinical practice and HS. The harmful effects of oxygen are highlighted to alert the clinician to this potential when there is an overabundance of oxygen.

RELEVANCE TO CLINICAL PRACTICE

oxygen is one of the most common drugs used in the medical community; however, the effects of oxygen on the body are not well understood. The use of oxygen if not prescribed correctly can cause cellular damage and death. Clinicians need to be more aware of the effects of oxygen and the damage it may cause if not administered properly.

Avoiding hyperoxemia during neonatal resuscitation: time to response of different SpO2 monitors

Aim

To assess the time to obtain reliable oxygen saturation readings by different pulse oximeters during neonatal resuscitation in the delivery room or NICU.

Methods

Prospective study comparing three different pulse oximeters: Masimo Radical-7 compared simultaneously with Ohmeda Biox 3700 or with Nellcor N395, in newborn infants who required resuscitation. Members of the research team placed the sensors for each of the pulse oximeters being compared simultaneously, one sensor on each foot of the same baby. Care provided routinely, without interference by the research team. The time elapsed until a reliable SpO2 was obtained was recorded using a digital chronometer. Statistical comparisons included chi-square and student's T-test.

Results

Thirty-two infants were enrolled; median gestational age 32 weeks. Seventeen paired measurements were made with the Radical-7 and Biox 3700; mean time to a stable reading was 20.2 ± 7 sec for the Radical-7 and 74.2 ± 12 sec for the Biox 3700 (p = 0.02). The Radical-7 and the N- 395 were paired on 15 infants; the times to obtain a stable reading were 20.9 ± 4 sec and 67.3 ± 12 sec, respectively (p = 0.03).

Conclusion

The time to a reliable reading obtained simultaneously in neonatal critical situations differs by the type of the pulse oximeter used, being significantly faster with Masimo Signal Extraction Technology. This may permit for better adjustments of inspired oxygen, aiding in the prevention of damage caused by unnecessary exposure to high or low oxygen.

Endotracheal intubation in a neonatal population remains associated with a high risk of adverse events

INTRODUCTION

There has been a significant increase in premedication use for neonatal intubation in the UK over the past decade. We aimed to determine the adverse events during neonatal intubation using the most commonly used premedication regimen in the UK.

DISCUSSION

We prospectively studied all intubations performed using morphine, suxamethonium and atropine during a 3-month period in three UK tertiary neonatal units. Premedication was administered for 87/93 (94%) of intubations. Median time taken to prepare premedication was 16 min (IQR 10-35). Median time to successful intubation was 5 min (IQR 2-9) following premedication. Median lowest recorded oxygen saturation after administration of premedication was 65% (IQR 39-85). A bradycardia in the range 61-99/min accompanied the procedure in 24/93 (26%) intubations, with a median duration of bradycardia of 8 s (IQR 1-10).

CONCLUSION

Despite the widespread move to premedication for neonatal intubation, many deficiencies in everyday practice remain. The rate of haemodynamic complications is high in this commonly used premedication regimen. This study shows that there are important factors to control at the local level in terms of timely preparation and administration of premedication drugs, training and supervision of staff carrying out this high-risk procedure.

Angiostatins decrease in the kidney of newborn piglets after hypoxia-reoxygenation

Little is known about the expression of kidney angiostatin in the hypoxia and reoxygenation of neonates. In this study, we compared the effect of 21% and 100% reoxygenation on kidney levels of angiostatin and its related factors in newborn piglets subjected to hypoxia-reoxygenation. Newborn piglets were subjected to 2h hypoxia followed by 1h of reoxygenation with either 21% or 100% oxygen and observed for 4days. There were 3 isoforms (38, 43 and 50kDa) of angiostatins identified in the kidney tissue of newborn piglets with the 38kDa being the major isoform (~60%). The 38kDa, but not 43 and 50kDa, angiostatin isoform correlated significantly with the levels of total angiostatin and plasminogen (r=0.95 and r=0.58, respectively). On day 4 of recovery in 100% hypoxic-reoxygenated group, there were decreases in kidney tissue levels of plasminogen, total angiostatin, angiostatin (38 and 43kDa, but not 50kDa), whereas no significant changes were found in the 21% hypoxic-reoxygenated group when compared to the sham-operated piglets with no hypoxia-reoxygenation. Both 21% and 100% hypoxic-reoxygenated groups did not show significant changes in kidney tissue levels of 50kDa angiostatin, MMP-2, MMP-9 and HIF-1alpha. In comparison to 21% oxygen, neonatal resuscitation with 100% oxygen decreased the kidney tissue levels of plasminogen and angiostatin that may play a role in neonatal kidney injury and altered renal development in adulthood.

Oxygen, temperature and humidity of inspired gases and their influences on airway and lung tissue in near-term lambs

PURPOSE

The relative contributions of factors influencing lung injury immediately after birth are poorly understood. We hypothesized that oxygen content and humidity of inspired air would influence markers of pulmonary inflammation in ventilated lambs.

METHODS

Lambs delivered at 140 days gestation (term = 150 days) were assigned to one of five groups (n = 5-6/group): unventilated controls, or ventilation with 21 or 100% O(2) that was either heated and humidified or cold and dry. Lambs were ventilated gently for 3 h: blood gases were recorded regularly. Bronchoalveolar lavage and samples of tracheal mucosa and lung were collected post mortem.

RESULTS

Arterial pH was lower [mean difference (95% CI): -0.07 (-0.13, -0.03)], while there was an increase in PaCO(2) [mean difference (95% CI): 10.2 (2.4, 17.9)] and fold change in lung pro-inflammatory IL-1beta cytokine mRNA [mean difference (95% CI): 28.3 (0.3, 56.2)] or IL-8 [mean difference (95% CI): 27.8 (7.9, 47.7)] cytokine mRNA expression with 100% O(2) relative to 21% O(2). Cold dry inspired gas did not influence gas exchange or dynamic mechanics at 3 h compared to heated humidified gas. Compared to 100% inspired O(2), cold dry inspired gas had less marked effect on fold change in lung pro-inflammatory IL-1beta cytokine mRNA [mean difference (95% CI): 27.2 (-0/8, 55.1)] or IL-8 [mean difference (95% CI): 14.5 (5.5, 34.4)] cytokine mRNA expression, although cilial dysfunction/damage was evident on electron microscopy, especially when exposure to cold dry gas was combined with hyperoxia.

CONCLUSIONS

In near-term neonatal lambs ventilated for 3 h, hyperoxia was associated a more powerful stimulus for pulmonary dysfunction and upregulation of inflammatory cytokines than cold dry gas.

Effect of hyperoxia on the ultrastructural pathology of alveolar epithelium in relation to glutathione peroxidase, lactate dehydrogenase activities, and free radical production in rats, Rattus norvigicus

Hyperoxia (HP) exposure inducts reactive oxygen species (ROS) in the lungs that may result in lung injury, including alveolar epithelial and endothelial cells. Lactate dehydrogenase (LDH) activity relates to glycolysis, whereas glutathione peroxidase (Gpx) activity relies on the pentose phosphate pathway (PPP). The purpose of this study was to examine early ROS-induced alveolar pathological changes in relation to the activity of glutathione peroxidase (GPx) and lactate dehydrogenase (LDH) activity. Twenty adult male rats, matched with age and body weight, were randomly assigned to two groups, control and experimental. The experimental group was exposed to hyperoxia for 24 h. Ultrastructure examination showed degenerated pneumocyte type I, containing swollen mitochondria associated with dilated rough endoplasmic reticulum, and was projecting into the alveolar lumen. Pneumocyte II showed mitochondria swelling and hyperplasia and was desquamated in structure, depleted in surfactant, and falling into the alveolar lumen. Pulmonary capillary showed distention without observed damage in the endothelial layer. Following HP, the average (+/-) free radical (FR) production increased significantly (p<.05) from the baseline control of 181.20+/-30.06 to 260.30+/-68.10 (Carr U) and average (+/-SD) GPx activity also increased significantly (p<.05) from the baseline control of 8178.30+/-2402.62 to 19,589.50+/-2392.44 (U/L), whereas average (+/-SD) LDH activity decreased significantly (p<.05) from baseline control of 194.11+/-75.52 to 42.68+/-11.41 (U/L), which demonstrated slowing down of glycolysis. Based on these results it can be concluded that exposure to high inspired oxygen inducted the buildup of mitochondria-driven ROS that was related to early injury in the alveolar epithelium without obvious endothelium injury.

Evaluation and management of the cyanotic neonate

The infant presenting to the emergency department with cyanosis requires rapid assessment, diagnosis, and initiation of therapy. In this article, the potential challenges in recognizing cyanosis are discussed, including the presence of higher concentrations of fetal hemoglobin, and its oxygen binding characteristics. A systematic approach to the diagnosis of cyanosis is presented, based on an understanding of the normal transitional physiology, and how diseases of the airway, lung, and circulatory system may disrupt these processes. Strategies for initial emergency department management of lung and cardiac disease are presented.

Oxygen saturation levels in the first 30 minutes of life

PURPOSE

To report a serendipitous finding from a larger investigation describing physiologic variability of healthy and sick pre- and full-term neonates transitioning to extrauterine life in whom the oxygen arterial saturations rose to 90% very quickly.

SUBJECTS

Thirty-four healthy pre- and full-term neonates and 40 sick pre- and full-term neonates.

DESIGN

Descriptive, comparative.

METHODS

Within the first 15-30 seconds of life, a pulse oximeter probe was placed on the dorsum of the neonate's foot. The signal was uploaded from the Hewlett Packard Viridia cardiopulmonary/oxygen saturation monitor to a data acquisition module at the bedside. Healthcare personnel performed their routine caregiving procedures for the neonate beginning transition to extrauterine life. They were at liberty to administer oxygen when they felt it was clinically necessary.

MAIN OUTCOME MEASURES

Oxygen saturation as measured by pulse oximetry.

PRINCIPAL RESULTS

Oxygen saturation values reached higher levels much faster for all groups of neonates than what has been previously reported in the literature.

CONCLUSIONS

In light of recent controversies regarding oxygen therapy, the practice of randomly administering oxygen to healthy infants at time of delivery should be examined.

Clinical practices in neonatal oxygenation: where have we failed? What can we do?

INTRODUCTION

Oxygen is among the most frequently used therapies in neonates worldwide. Nevertheless, many times it is used unnecessarily. Neonatal practices have changed over the last several years; treatments originally believed to be beneficial have been discarded.

STUDY DESIGN

Oxygen utilized 'just in case' or 'prophylactically' can lead to great damage previously ignored and/or unseen by healthcare providers. It is imperative to improve education on neonatal oxygenation and saturation monitoring. It is also important not to depend on old assumptions, which were not based on evidences. The potential for unseen damage at the cellular and tissue levels cannot be ignored. Therapies that prove to be outdated or even dangerous must be eliminated while further research and confirmation of the best practices are determined. Freedom to choose can come at a price.

Expression of angiostatin and its related factors in the plasma of newborn pigs with hypoxia and reoxygenation

Little is known about angiostatin and its related factors in the hypoxia-reoxygenation of neonates. In this study we compared the effect of 21% and 100% reoxygenation on temporal changes in the plasma level of these factors in newborn piglets subjected to hypoxia. Newborn piglets were subjected to 2 h hypoxia followed by 1 h of reoxygenation with either 21% or 100% oxygen and observed for 4 days. On day 4 of recovery in 100% hypoxic-reoxygenated group, there were increases in total angiostatin, plasminogen/plasmin and MMP-2 levels, and decreases in VEGF levels (vs. respective baseline levels, all P <0.001), whereas no significant temporal changes were found in the 21% hypoxic-reoxygenated and sham-operated groups. Angiostatin levels correlated positively with the levels of MMP-2 and HIF-1alpha and negatively with VEGF levels in 100% hypoxic-reoxygenated group (all P <0.05). In comparison to 21% oxygen, neonatal resuscitation with 100% oxygen was found to increase the levels anti-angiogenic factors.

Pulmonary hemodynamics in neonatal lambs resuscitated with 21%, 50%, and 100% oxygen

The effect of resuscitation with varying levels of O2 on pulmonary hemodynamics at birth is not well known. We hypothesized that the decrease in pulmonary vascular resistance (PVR) and subsequent response to pulmonary vasoconstrictors and vasodilators will differ following resuscitation with 21%, 50%, or 100% O2 for 30 min at birth in normal term lambs. Lambs at 141 d gestation were delivered by cesarean section and ventilated with 21% (21% Res; n=6), 50% (50% Res; n=6), or 100% 02 (100% Res; n=7) for 30 min followed by ventilation with 21% O2 in all three groups. A greater decrease in PVR was seen with 50% and 100% O2 ventilation than with 21% O2 (0.21 +/- 0.02, 0.21 +/- 0.02, and 0.34 +/- 0.05 mm Hg/mL/min/kg, respectively). Subsequent pulmonary vasoconstriction to hypoxia (10% O2) and the thromboxane,analog U46619 (0.5 and 1 mcirog/kg/min) was similar in all three groups. After inducing a stable elevation in PVR with U46619, impaired pulmonary vasodilation to inhaled NO (59 +/- 4, 65 +/- 4, and 74 +/- 5% of baseline PVR with 21, 50, and 100%Res, respectively) and acetylcholine infusion (67 +/- 8, 75 +/- 6, and 87 +/- 4% of baseline PVR with 21, 50, and 100%Res, respectively) and rebound pulmonary hypertension following their withdrawal were observed in the 100%Res group. We conclude that, while ventilation with 100% O2 at birth results in a greater initial decrease in PVR, subsequent pulmonary vasodilation to NO/acetylcholine is impaired.

Anti-oxidant strategies

Oxidative stress plays an important role in causing organ injury in the compromised fetus and neonate. Recent experimental research and clinical studies have clarified important pathways in the production of reactive oxygen and nitrogen species. Free radicals are involved in causing cerebral damage after perinatal hypoxia-ischemia affecting membrane lipids, proteins, and DNA. Anti-oxidant strategies can be used as add-on neuroprotective therapy after perinatal oxidative stress. Selective inhibitors of neuronal and inducible nitric oxide synthase, allopurinol, melatonin, and erythropoietin are among the first compounds that are ready for clinical trials.

Oxygen as a neonatal health hazard: call for détente in clinical practice

Education in oxygenation and in how oxygen is given to newborns needs to increase. Treatment with oxygen should no longer be considered proverbial and customary, regardless of our 'past experience' or consensus recommendations in clinical guidelines, since oxygen may lead to acute or chronic health effects.

CONCLUSION

Inappropriate oxygen use is a neonatal health hazard associated with aging, DNA damage and cancer, retinopathy of prematurity, injury to the developing brain, infection and others. Neonatal exposure to pure O2, even if brief, or to pulse oximetry >95% when breathing supplemental O2 must be avoided as much as possible.

TEMPORAL PLATELET AGGREGATORY FUNCTION IN HYPOXIC NEWBORN PIGLETS REOXYGENATED WITH 18%, 21%, AND 100% OXYGEN

Thromboembolic and bleeding complications are common after asphyxia. We studied the temporal effects of different oxygen concentrations used in resuscitating hypoxic newborn piglets on platelet aggregatory function. Alveolar normocapnic hypoxia (fractional inspired oxygen concentration = 0.15) was induced in piglets (1-4 d, 1.7-2.5 kg) for 2 h, followed by reoxygenation with 18%, 21%, or 100% oxygen for 1 h and then 21% for 2 h (n = 8-9 per group). Control piglets underwent surgery with no hypoxia-reoxygenation (n = 5). Platelet counts and collagen-stimulated (2-10 microg/mL) whole blood aggregation were studied at normoxic baseline and at 3 h, 2 d, and 4 d of recovery. Platelet activation markers including plasma thromboxane B2 and matrix metalloproteinase 2 and 9 levels were measured. At 2 h hypoxia (mean PaO2 30-35 mmHg), all piglets were hypotensive and acidotic (mean pH 7.19-7.24). In 100% reoxygenation piglets, the concentration-response curves of collagen-stimulated platelet aggregation were significantly shifted upward at 3 h and 2 d of recovery with no differences in the collagen concentration required to induce 50% of maximum aggregation, and this normalized to baseline on 4 d. In the 18% and 21% reoxygenated groups, there were no changes in platelet aggregation during the experiment. Platelet counts were not different between groups and over time. Hypoxic-reoxygenated piglets had increased plasma thromboxane B2 (100% group) and matrix metalloproteinase-2 levels (21% and 100% groups) (versus respective baseline, P < 0.05), with no difference between experimental groups. These findings suggest transient platelet activation in hypoxic newborn piglets resuscitated with 100% but not with 18% and 21% oxygen, of which the clinical significance requires further investigation.

Executive summary of the workshop on oxygen in neonatal therapies: controversies and opportunities for research

One of the most complex areas in perinatal/neonatal medicine is the use of oxygen in neonatal therapies. To address the knowledge gaps that preclude optimal, evidence-based care in this critical field of perinatal medicine, the National Institute of Child Health and Human Development organized a workshop, Oxygen in Neonatal Therapies: Controversies and Opportunities for Research, in August 2005. The information presented at the workshop included basic and translational oxygen research; a review of completed, ongoing, and planned clinical trials; oxygen administration for neonatal resuscitation; and a review of the collaborative home infant monitoring evaluation study. This article provides a summary of the discussions, focusing on major knowledge gaps, with prioritized suggestions for studies in this area.

New guidelines for newborn resuscitation

The new guidelines from the International Liaison Committee on Resuscitation and American Heart Association/American Academy of Pediatrics for newborn resuscitation underline that efficient ventilation is the key to a successful resuscitation of the newly born infant. Compared with the former guidelines published in 1999, the major changes are (i) less emphasis on using supplemental oxygen when initiating resuscitation, (ii) no need for routine intrapartum oropharyngeal and nasopharyngeal suctioning for vigorous infants born to mothers with meconium staining of amniotic fluid, (iii) occlusive wrapping of very low birth weight infants <28 weeks to reduce heat loss is recommended, (iv) preference for the intravenous versus endotracheal route for adrenaline and (v) more emphasis on parental autonomy at the threshold of viability. A number of gaps in newborn resuscitation have been identified and discussed.

CONCLUSION

The new guidelines for newborn resuscitation are more evidence-based than previously ones. However, still there is a need for further research and modifications.

Optimal oxygenation at birth and in the neonatal period

BACKGROUND

In recent years it has become clear that even a brief exposure to high oxygen concentration at birth and an oxygen saturation (SaO(2)) >93-95% in extremely low birth weight (ELBW) infants is more toxic than previously believed.

OBJECTIVE

To summarize and review clinical studies published to date either dealing with resuscitation of newborn infants with different oxygen concentrations or the use of high or low SaO(2) in the neonatal period of ELBW infants.

RESULTS

Three systematic reviews of five trials and seven individual studies including up to 2,011 newborn infants have shown that neonatal mortality is reduced by 30-40% if resuscitation is carried out with 21% instead of 100% O(2). Room air resuscitation also leads to faster early recovery and need for shorter duration of resuscitation. Six studies of ELBW infants have shown that retinopathy of prematurity and chronic lung disease are significantly reduced if SaO(2) is kept <93-95% compared with higher saturations. Avoidance of fluctuations in SaO(2) also seems to be important. Two observational studies suggest a significant 2.5- to 3.5-fold increased risk of childhood cancer in infants resuscitated with 100% O(2) for a few minutes.

CONCLUSIONS

To date there are sufficient data available to recommend that newborn resuscitation should not be carried out with 100% O(2). In ELBW infants, SaO(2) levels should be kept between 85 and 93% or possibly between 88 and 95%, but should definitely not exceed 95%. Fluctuations should be avoided.