Terje Rootwelt

Resuscitation of asphyxiated newborn infants with room air or oxygen : an international controlled trial : The Resair 2 study

Objective. Birth asphyxia represents a serious problem worldwide, resulting in ∼1 million deaths and an equal number of serious sequelae annually. It is therefore important to develop new and better ways to treat asphyxia. Resuscitation after birth asphyxia traditionally has been carried out with 100% oxygen, and most guidelines and textbooks recommend this; however, the scientific background for this has never been established. On the contrary, theoretic considerations indicate that resuscitation with high oxygen concentrations could have detrimental effects. We have performed a series of animal studies as well as one pilot study indicating that resuscitation can be performed with room air just as efficiently as with 100% oxygen. To test this more thoroughly, we organized a multicenter study and hypothesized that room air is superior to 100% oxygen when asphyxiated newborn infants are resuscitated. Methodology. In a prospective, international, controlled multicenter study including 11 centers from six countries, asphyxiated newborn infants with birth weight >999 g were allocated to resuscitation with either room air or 100% oxygen. The study was not blinded, and the patients were allocated to one of the two treatment groups according to date of birth. Those born on even dates were resuscitated with room air and those born on odd dates with 100% oxygen. Informed consent was not obtained until after the initial resuscitation, an arrangement in agreement with the new proposal of the US Food and Drug Administrations rules governing investigational drugs and medical devices to permit clinical research on emergency care without the consent of subjects. The protocol was approved by the ethical committees at each participating center. Entry criterion was apnea or gasping with heart rate <80 beats per minute at birth necessitating resuscitation. Exclusion criteria were birth weight <1000 g, lethal anomalies, hydrops, cyanotic congenital heart defects, and stillbirths. Primary outcome measures were death within 1 week and/or presence of hypoxic–ischemic encephalopathy, grade II or III, according to a modification of Sarnat and Sarnat. Secondary outcome measures were Apgar score at 5 minutes, heart rate at 90 seconds, time to first breath, time to first cry, duration of resuscitation, arterial blood gases and acid base status at 10 and 30 minutes of age, and abnormal neurologic examination at 4 weeks. The existing routines for resuscitation in each participating unit were followed, and the ventilation techniques described by the American Heart Association were used as guidelines aiming at a frequency of manual ventilation of 40 to 60 breaths per minute. Results. Forms for 703 enrolled infants from 11 centers were received by the steering committee. All 94 patients from one of the centers were excluded because of violation of the inclusion criteria in 86 of these. Therefore, the final number of infants enrolled in the study was 609 (from 10 centers), with 288 in the room air group and 321 in the oxygen group. Median (5 to 95 percentile) gestational ages were 38 (32.0 to 42.0) and 38 (31.1 to 41.5) weeks (NS), and birth weights were 2600 (1320 to 4078) g and 2560 (1303 to 3900) g (NS) in the room air and oxygen groups, respectively. There were 46% girls in the room air and 41% in the oxygen group (NS). Mortality in the first 7 days of life was 12.2% and 15.0% in the room air and oxygen groups, respectively; adjusted odds ratio (OR) = 0.82 with 95% confidence intervals (CI) = 0.50–1.35. Neonatal mortality was 13.9% and 19.0%; adjusted OR = 0.72 with 95% CI = 0.45–1.15. Death within 7 days of life and/or moderate or severe hypoxic–ischemic encephalopathy (primary outcome measure) was seen in 21.2% in the room air group and in 23.7% in the oxygen group; OR = 0.94 with 95% CI = 0.63–1.40. Heart rates did not differ between the two groups at any time point and were (mean ± SD) 90 ± 31 versus 93 ± 33 beats per minute at 1 minute and 110 ± 27 versus 113 ± 30 beats per minute at 90 seconds in the room air and oxygen groups, respectively. Apgar scores at 1 minute (median and 5 to 95 percentiles) were significantly higher in the room air group (5 [1 to 6.7]) than in the oxygen group (4 [1 to 7]); however, at 5 minutes there were no significant differences, with 8 (4 to 9) versus 7 (3 to 9). There were significantly more infants with very low 1-minute Apgar scores (<4) in the oxygen group (44.4%) than in the room air group (32.3%). There also were significantly more infants with 5-minute Apgar score <7 in the oxygen group (31.8%) than in the room air group (24.8%). There were no differences in acid base status or Sao 2during the observation period between the two groups. Mean (SD) Pao 2 was 31 (17) versus 30 (22) mm Hg in cord blood in the room air and oxygen groups, respectively (NS). At 10 minutes Pao 2 was 76 (32) versus 87 (49) mm Hg (NS), and at 30 minutes, the values were 74 (29) versus 89 (42) mm Hg in the room air and oxygen groups, respectively. Median (95% CI) time to first breath was 1.1 (1.0–1.2) minutes in the room air group versus 1.5 (1.4 to 1.6) minutes in the oxygen group. Time to the first cry also was in mean 0.4 minute shorter in the room air group compared with the oxygen group. In the room air group, there were 25.7% so-called resuscitation failures (bradycardia and/or central cyanosis after 90 seconds) that were switched to 100% oxygen after 90 seconds. The percentage of resuscitation failures in the oxygen group was 29.8%. Conclusions. This study with patients enrolled primarily from developing countries indicates that asphyxiated newborn infants can be resuscitated with room air as efficiently as with pure oxygen. In fact, time to first breath and first cry was significantly shorter in room air- versus oxygen-resuscitated infants. Resuscitation with 100% oxygen may depress ventilation and therefore delay the first breath. More studies are needed confirming these results before resuscitation guidelines are changed.

Resuscitation of Asphyxic Newborn Infants with Room Air or 100% Oxygen

ABSTRACT: To test the hypothesis that room air is superior to 100% oxygen when asphyxiated newborns are resuscitated, 84 neonates (birth weight > 999 g) with heart rate <80 and/or apnea at birth were allocated to be resuscitated with either room air (n = 42) or 100% oxygen (n = 42). Serial, unblinded observations of heart rates at 1, 3, 5, and 10 min and Apgar scores at 1 min revealed no significant differences between the two groups. At 5 min, median (25th and 75th percentile) Apgar scores were higher in the room air than in the oxygen group [8 (7–9) versus 7 (6–8), p = 0.03]. After the initial resuscitation, arterial partial pressure of oxygen, pH, and base excess were comparable in the two groups. Assisted ventilation was necessary for 2.4 (1.5–3.4) min in the room air group and 3.0 (2.0–4.0) min in the oxygen group (p = 0.14). The median time to first breath was 1.5 (1.0–2.0) min in both the room air and oxygen groups (p = 0.59), and the time to first cry was 3.0 (2.0–4.0) min and 3.5 (2.5–5.5) min in the room air and oxygen groups, respectively (p = 0.19). Three neonates in the room air group and four in the oxygen group died in the neonatal period. At 28 d, 72 of the 77 surviving neonates were available for follow-up (36 in each group), and none had any neurologic sequelae. This preliminary study did not provide conclusive evidence that room air is superior to 100% oxygen in the resuscitation of asphyxiated newborns, although it indicated that room air is as effective as 100% oxygen. Additional trials with increased numbers of patients are necessary before deciding whether room air or oxygen should be used in clinical practice.

Hypoxemia and reoxygenation with 21% or 100% oxygen in newborn pigs : changes in blood pressure, base deficit, and hypoxanthine and brain morphology

ABSTRACT: To study whether room air is as effective as 100% O2 in resuscitation after hypoxia, hypoxemia (Pao2 2.3–4.3 kPa) was induced in newborn pigs (2–5 d old) by ventilation with 8% O2 in nitrogen. When systolic blood pressure had fallen to 20 mm Hg, animals were randomly reoxygenated with either 21% O2 (group 1, n = 9) or 100% O2 (group 2, n = 11) for 20 min followed by 21% O2 in both groups. Controls (group 3, n = 5) were ventilated with 21% O2 throughout the experiment. Base deficit peaked at 31 ± 5 mmol/L (mean ± SD) for both hypoxic groups at 5 min of reoxygenation and then normalized over the following 3 h. There were no statistically significant differences between the two groups during reoxygenation concerning blood pressure, heart rate, base deficit, or plasma hypoxanthine. Hypoxanthine peaked at 165 ± 40 and 143 ± 42 μmol/L in group 1 and 2 (NS), respectively, and was eliminated monoexponentially in both groups with an initial half-life for excess hypoxanthine of 48 ± 21 and 51 ± 27 min (NS), respectively. Blinded pathologic examination of cerebral cortex, cerebellum, and hippocampus after 4 d showed no statistically significant differences with regard to brain damage. We conclude that 21% O2 is as effective as 100% O2 for normalizing blood pressure, heart rate, base deficit, and plasma hypoxanthine after severe neonatal hypoxemia in piglets and that the extent of the hypoxic brain damage is similar in the two groups.

Effect of barbiturates on hydroxyl radicals, lipid peroxidation, and hypoxic cell death in human NT2-N neurons.

Background: Barbiturates have been shown to be neuroprotective in several animal models, but the underlying mechanisms are unknown. In this study, the authors investigated the effect of barbiturates on free radical scavenging and attempted to correlate this with their neuroprotective effects in a model of hypoxic cell death in human NT2-N neurons. Methods: Hydroxyl radicals were generated by ascorbic acid and iron and were measured by conversion of salicylate to 2,3-dihydroxybenzoic acid. The effect of barbiturates on lipid peroxidation measured as malondialdehyde and 4-hydroxynon-2-enal was also investigated. Hypoxia studies were then performed on human NT2-N neurons. The cells were exposed to 10 h of hypoxia or combined oxygen and glucose deprivation for 3 or 5 h in the presence of thiopental (50–600 &mgr;M), methohexital (50–400 &mgr;M), phenobarbital (10–400 &mgr;M), or pentobarbital (10–400 &mgr;M), and cell death was evaluated after 24 h by lactate dehydrogenase release. Results: Pentobarbital, phenobarbital, methohexital, and thiopental dose-dependently inhibited formation of 2,3-dihydroxybenzoic acid and iron-stimulated lipid peroxidation. There were significant but moderate differences in antioxidant action between the barbiturates. While phenobarbital (10–400 &mgr;M) and pentobarbital (10–50 &mgr;M) increased lactate dehydrogenase release after combined oxygen and glucose deprivation, thiopental and methohexital protected the neurons at all tested concentrations. At a higher concentration (400 &mgr;M), pentobarbital also significantly protected the neurons. At both 50 and 400 &mgr;M, thiopental and methohexital protected the NT2-N neurons significantly better than phenobarbital and pentobarbital. Conclusions: Barbiturates differ markedly in their neuroprotective effects against combined oxygen and glucose deprivation in human NT2-N neurons. The variation in neuroprotective effects could only partly be explained by differences in antioxidant action.

An overview of L‐2‐hydroxyglutarate dehydrogenase gene (L2HGDH) variants: a genotype–phenotype study

L‐2‐Hydroxyglutaric aciduria (L2HGA) is a rare, neurometabolic disorder with an autosomal recessive mode of inheritance. Affected individuals only have neurological manifestations, including psychomotor retardation, cerebellar ataxia, and more variably macrocephaly, or epilepsy. The diagnosis of L2HGA can be made based on magnetic resonance imaging (MRI), biochemical analysis, and mutational analysis of L2HGDH. About 200 patients with elevated concentrations of 2‐hydroxyglutarate (2HG) in the urine were referred for chiral determination of 2HG and L2HGDH mutational analysis. All patients with increased L2HG (n=106; 83 families) were included. Clinical information on 61 patients was obtained via questionnaires. In 82 families the mutations were detected by direct sequence analysis and/or multiplex ligation dependent probe amplification (MLPA), including one case where MLPA was essential to detect the second allele. In another case RT‐PCR followed by deep intronic sequencing was needed to detect the mutation. Thirty‐five novel mutations as well as 35 reported mutations and 14 nondisease‐related variants are reviewed and included in a novel Leiden Open source Variation Database (LOVD) for L2HGDH variants (http://www.LOVD.nl/L2HGDH). Every user can access the database and submit variants/patients. Furthermore, we report on the phenotype, including neurological manifestations and urinary levels of L2HG, and we evaluate the phenotype–genotype relationship. Hum Mutat 30:1–11, 2010.

Effects of hypoxemia and reoxygenation with 21% or 100% oxygen in newborn piglets: extracellular hypoxanthine in cerebral cortex and femoral muscle.

OBJECTIVE To determine whether reoxygenation with an FIO2 of 0.21 (21% oxygen) is preferable to an FIO2 of 1.0 (100% oxygen) in normalizing brain and muscle hypoxia in the newborn. DESIGN Prospective, randomized, animal study. SETTING Hospital surgical research laboratory. SUBJECTS Twenty-six anesthetized, mechanically ventilated, domestic piglets, 2 to 5 days of age. INTERVENTIONS The piglets were randomized to control or hypoxemia groups. Hypoxemia was induced by ventilating the piglets with 8% oxygen in nitrogen, which was continued until mean arterial pressure decreased to <20 mm Hg. After hypoxemia, the piglets were further randomized to receive reoxygenation with an FIO2 of 0.21 (21% oxygen group, n = 9) or an FIO2 of 1.0 for 30 mins followed by an FIO2 of 0.21 (100% oxygen group, n = 9), and followed for 5 hrs. The piglets in the control group were mechanically ventilated with 21% oxygen (n = 8). MEASUREMENTS AND MAIN RESULTS We measured extracellular concentrations of hypoxanthine in the cerebral cortex and femoral muscle (in vivo microdialysis), plasma hypoxanthine concentrations, cerebral arterial-venous differences for hypoxanthine, acid base balances, arterial and venous (sagittal sinus) blood gases, and mean arterial pressures. The lowest pH values of 6.91 +/- 0.11 (21% oxygen group, mean +/- SD) and 6.90 +/- 0.07 (100% oxygen group) were reached at the end of hypoxemia and then normalized during the reoxygenation period. Plasma hypoxanthine increased during hypoxemia from 28.1 +/- 9.3 to 119.1 +/- 31.9 micromol/L in the 21% oxygen group (p < .001) and from 32.6 +/0- 14.5 to 135.0 +/- 31.4 micromol/L in the 100% oxygen group (p <.001). Plasma hypoxanthine concentrations then normalized over the next 2 hrs in both groups. In the cerebral cortex, extracellular concentrations of hypoxanthine increased during hypoxemia from 3.9 +/- 2.8 to 20.2 +/- 7.4 micromol/L in the 21% oxygen group (p < .001) and from 5.9 +/- 5.0 to 25.1 +/- 7.1 micromol/L in the 100% oxygen group (p < .001). In contrast to plasma hypoxanthine, extracellular hypoxanthine in the cerebral cortex increased significantly further during early reoxygenation, and, within the first 30 mins, reached maximum values of 24.9 +/- 6.3 micromol/L in the 21% oxygen group (p < .01) and 34.8 +/- 10.9 micromol/L in the 100% oxygen group (p < .001). This increase was significantly larger in the 100% oxygen group than in the 21% oxygen group (9.7 +/- 4.7 vs. 4.7 +/- 2.6 micromol/L, p < .05). There were no significant differences between the two reoxygenated groups in duration of hypoxemia, hypoxanthine concentrations in femoral muscle, plasma hypoxanthine concentrations, pH, or mean arterial pressure. The cerebral arterial-venous difference for hypoxanthine was positive both at baseline, at the end of hypoxemia, and after 30 mins and 300 mins of reoxygenation, and no differences were found between the two reoxygenated groups. CONCLUSIONS Significantly higher extracellular concentrations of hypoxanthine were found in the cerebral cortex during the initial period of reoxygenation with 100% oxygen compared with 21% oxygen. Hypoxanthine is a marker of hypoxia, and reflects the intracellular energy status. These results therefore suggest a possibly more severe impairment of energy metabolism in the cerebral cortex or an increased blood-brain barrier damage during reoxygenation with 100% oxygen compared with 21% oxygen in this newborn piglet hypoxia model.

Response to resuscitation of the newborn: Early prognostic variables

AIM To characterize the development of clinically relevant variables the first minutes after birth and identify early prognostic markers in newborn infants requiring resuscitation. METHODS A database of 591 infants resuscitated with either 21% or 100% oxygen was analysed. Time to first breath, development in heart rate, Apgar scores, arterial oxygen saturation (SaO(2)), and base deficit (BD) are described in relation to different degrees of birth depression and outcomes. RESULTS Heart rate and Apgar scores increased quickly even in the most depressed infants but were significantly lower in those having a poor outcome. By contrast, BD normalized at the same rate, 6-7 mmol/l/h, in the first hour of life regardless of the degree of birth depression and outcome. SaO(2) values increased as quickly in room air as in 100%-oxygen-resuscitated infants. Time to first breath was prolonged threefold, from 1 to 3 min, in the most depressed (1-min Apgar score < 4) compared with the less depressed infants. Highest odds ratio (OR) for death in the first week of life or for development of hypoxic-ischaemic encephalopathy (HIE) stage 2 and 3 was a 5-min heart rate < or =60 bpm (OR 16.5 for both death and HIE) and Apgar < 4 (OR 14 and 18.8). Neonatal survival for HIE stage 1, 2, and 3 was 93%, 63%, and 11%, respectively. OR for early neonatal death, if SaO(2) < or =60% at 1 min, was 8.6 (sensitivity 0.82 and specificity 0.65). CONCLUSION Apgar scores, heart rate, SaO(2), and time to first breath in newly born infants in need of resuscitation may be used for early identification of infants with a poor prognosis. These data may be helpful in describing the severity of depression in single infants and to select infants in need of interventional therapy.

The neuronal regulation of fracture healing: Effects of sciatic nerve resection in rat tibia

The effect of sciatic nerve resection on tibial fracture healing was studied in rats 25 days post-trauma. To prevent differences in loading between sham-operated and nerve-resected animals the fractured limbs were cast-immobilized. On radiograms 8 of 11 fractures in the sham-operated animals showed very little callus formation in contrast to only 1 of 8 fractures in the group with nerve resection. Measured by single-photon absorptiometry, animals with sciatic nerve resection had a higher bone mineral content than the sham-operated animals. However, the mechanical strength in three-point cantilever bending was not better in the nerve-resected rats, implying a defective organization of the large callus. These results suggest neural regulation plays a role in the type of fracture healing, primary or secondary, and in the amount and quality of the callus.

Bilirubin induces apoptosis and necrosis in human NT2-N neurons.

Studies on primary cultures of newborn rodent neurons have suggested that neuronal death induced by unconjugated bilirubin (UCB) is mainly apoptotic in nature. We exposed a human teratocarcinoma-derived cell line, NT2-N neurons, to different concentrations of UCB and albumin at a 1.5 molar ratio and used multiple, independent measures of cell damage to evaluate neuronal injury after 6, 24, and 48 h. Low doses of UCB (0.66, 2, and 5 μM) induced a moderate loss of 3–4[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide (MTT) cleavage accompanied by delayed morphologic changes consistent with apoptosis (2 and 5 μM). Moderate concentrations of UCB (10 and 25 μM) resulted in early (6 h) necrosis in a subset of neurons, while remaining neurons underwent progressive impairment of MTT cleavage and increasing lactate dehydrogenase (LDH) release accompanied by predominantly delayed apoptosis. High concentrations of UCB (100 μM) induced severe impairment of MTT cleavage, extensive LDH release, and morphologic changes consistent with necrosis within 6 h. Used as a positive control for apoptosis, 2 μM STS induced progressive impairment of MTT cleavage and morphologic changes consistent with apoptosis over the entire observation period. DNA electrophoresis at 48 h was compatible with apoptosis both after treatment with STS and UCB concentrations ≤25, but not at 100 μM. Cleavage of poly (ADP-ribose) polymerase (PARP) was only seen in neurons treated with low UCB concentrations and STS. We conclude that UCB induces early necrosis at high and moderate concentrations and predominantly delayed apoptosis at low and moderate concentrations in cultured human NT2-N neurons.

Hypoxic Cell Death in Human NT2‐N Neurons: Involvement of NMDA and Non‐NMDA Glutamate Receptors

Abstract: Human NTera2 teratocarcinoma cells were differentiated into postmitotic NT2‐N neurons and exposed to hypoxia for 6 h. The cultures were evaluated microscopically, and percent lactate dehydrogenase (LDH) release after 24 and 48 h was used as an assay for cell death. After 48 h LDH release was 24.3 ± 5.6% versus 13.8 ± 3.7% in controls (p < 0.001). Cell death was greatly diminished by MK‐801 pretreatment (15.4 ± 5.1%, p < 0.001). If glutamate was omitted from the medium, glutamate levels after 6 h of hypoxia were reduced from 101 ± 63 to 2.3 ± 0.3 µM, and cell death at 48 h was also markedly reduced (15.4 ± 4.5%, p < 0.001). The α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate antagonist 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (18.7 ± 5.1%, p < 0.001) and mild hypothermia (33.5–34°C) during hypoxia (19.5 ± 2.75, p < 0.05) were moderately protective. Basic fibroblast growth factor (24.1 ± 3.2%), the nitric oxide synthase inhibitor NG‐nitro‐l‐arginine methyl ester (22.8 ± 8.1%), the antioxidant N‐tert‐butyl‐o‐phenylnitrone (18.9 ± 5.9%), and the 21‐aminosteroid U74389G (24.0 ± 3.4%) did not protect the cells. N‐Acetyl‐l‐cysteine even tended to increase cell death (30.1 ± 2.5%, p = 0.06). Treatment with MK‐801 at the end of hypoxia did not reduce cell death (23.3 ± 2.3%). In separate experiments, a 15‐min exposure to 1 mM glutamate without hypoxia did not result in significant cell death (14.7 ± 2.4 vs. 12.2 ± 2.1%,p = 0.07). We conclude that, although somewhat resistant to glutamate toxicity when normoxic, NT2‐N neurons die via an ionotropic glutamate receptor‐mediated mechanism when exposed to hypoxia in the presence of glutamate. As far as we know, this is the first reported analysis of the mechanism of hypoxic cell death in cultured human neuronlike cells.