Referral pattern of neonates with severe respiratory failure for extracorporeal membrane oxygenation

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) remains the mainstay of management in neonates with severe but potentially reversible respiratory failure. In the UK, ECMO is available only as a supraregional service at four centres.

OBJECTIVE

To explore regional variations in ECMO referrals and neonatal deaths due to severe respiratory failure in England, Wales and Northern Ireland.

METHODS

In this retrospective study, data regarding ECMO referrals due to neonatal respiratory failure from January to December 2002 were obtained from the four UK ECMO centres and then subdivided according to the Government Office Regions. Anonymised data regarding neonatal deaths was obtained from Confidential Enquiry into Maternal and Child Health. Neonatal deaths were classified into four groups (group 1: deaths potentially avoidable by ECMO; group 2: deaths where it was unclear whether ECMO would have been of benefit; group 3: neonates not eligible for ECMO; and group 4: data inadequate to classify deaths).

RESULTS

There was significant regional variation in the rates of both ECMO referral (0.10 to 0.46 per 1000 live births; (p<0.001)) and neonatal deaths (groups 1 and 2) (0.09 to 0.32 per 1000 live births; (p<0.001)). Regions with high referral rates for ECMO tended towards having higher group 1 plus group 2 neonatal death rates (correlation coefficient = 0.75).

CONCLUSION

It is possible that there are significant regional variations in the uptake of ECMO and in neonatal mortality due to severe respiratory failure. A confidential prospective study may further clarify these observations and identify the factors that might lead to these variations.

Ethnic variations in the incidence and outcome of severe retinopathy of prematurity

BACKGROUND

The aim of this study was to assess the incidence and outcome of severe retinopathy of prematurity (ROP) among different ethnic groups in a geographically defined population in the U.K. Severe ROP was defined as any stage 3 or worse disease.

METHODS

This was a retrospective study of children born over a 6-year period with a birth weight of 1250 g or less. Threshold ROP was treated with diode laser.

RESULTS

Severe disease developed in 37 out of 355 neonates (10.4%) who underwent ROP screening. The difference in the incidence of severe ROP between infants of Caucasian and South Asian ethnic origin was not statistically significant: 10.2% vs. 10.8% (odds ratio = 1.06; 95% confidence interval: 0.44 to 2.57). This conclusion held after single-variable adjustment for birth weight, gestational age, and score on the Clinical Risk Index for Babies. The incidence of threshold ROP was 3% among infants of both Caucasian and South Asian ethnic origin. There was no significant difference in terms of visual outcome between the Caucasian and South Asian infants.

INTERPRETATION

This study showed no statistical evidence for a difference in the incidence or outcome of severe ROP among infants of South Asian ethnic origin compared with those of Caucasian origin. Although the small numbers in our study mean that a clinically important difference cannot be excluded, it is very unlikely that the 5-fold higher incidence in Asian babies described in the literature is correct for the population from which our subjects were drawn.

Neonatal ventilation with inhaled nitric oxide vs. ventilatory support without inhaled nitric oxide for infants with severe respiratory failure born at or near term: the INNOVO multicentre randomised controlled trial

BACKGROUND

Evidence from European centres to support the use of nitric oxide (NO) in mature newborns with evidence of severe respiratory failure is sparse.

METHODS

Infants of >33 weeks' gestation, <28 days old, and with severe respiratory failure requiring ventilatory support were randomised to receive or not to receive inhaled NO (iNO). The study was not blinded.

RESULTS

Sixty infants were recruited (29 allocated iNO, 31 no iNO) from 15 neonatal units in the UK, Finland, Belgium and the Republic of Ireland. 15/60 recruited babies died, and 8.1% of the survivors (4/45) were classified as severely disabled at 1 year. There was no statistically significant difference between the randomised groups in terms of the primary outcome of death or severe disability by the corrected age of 1 year (relative risk = 0.96 (95% confidence interval = 0.46-2.03); p = 0.86) (Fisher's exact p = 1.00). The costs of NO were outweighed by reduced extra corporeal membrane oxygenation costs in the iNO group. The mean total hospitalisation costs were lower in the iNO group, although the mean difference (1,697 pounds) was not statistically significant (95% confidence interval = -14,472 to 11,478).

CONCLUSIONS

The results complement those of previous studies that suggest NO is cost-effective and reduces the need for extra corporeal membrane oxygenation in this group of babies. Overall survival rates compare unfavourably with results of US trials.

Rotational excitation of H2O by cold electrons

Experimental data are presented for the scattering of electrons by H2O between 17 and 250 meV impact energy. These results are used in conjunction with a generally applicable method, based on a quantum defect theory approach to electron-polar molecule collisions, to derive the first set of data for state-to-state rotationally inelastic scattering cross sections based on experimental values.

A dose response study of inhaled nitric oxide in hypoxic respiratory failure in preterm infants

BACKGROUND

Inhaled nitric oxide (iNO) is used widely in newborn infants with hypoxic respiratory failure, despite the known and theoretical toxicity of iNO, and a relative lack of information about appropriate doses.

AIM

To determine whether a dose-response relationship existed for iNO in preterm infants.

DESIGN

A four-period, four-dose, cross-over design was used with iNO given for 15 min in a randomised sequence in concentrations of 5, 10, 20 and 40 parts per million (ppm), with a minimum 5 min wash-out period. Data on ventilatory, blood gas and other physiological measurements were recorded before and at the end of each period. The relationship of clinical response with iNO dose and period was analysed using multivariate regression.

SUBJECTS

Infants with gestational age < 34 weeks and < 28 days postnatal age with hypoxic respiratory failure were recruited.

OUTCOME MEASURE

A clinically significant dose-response was defined as a rise in the post-ductal arterial oxygen tension (PaO(2)) of at least 3 kPa.

RESULTS

Thirteen infants were recruited. At trial entry, ten were < 3 days of age; 11 were being treated with high frequency oscillatory ventilation; median (inter-quartile range) gestational age 27 (25-29) weeks; birthweight 983 (765-1120) g; oxygenation index 27.1 (21.8-28.8). Six infants (46%) showed a clinically significant response. After adjusting for period and patient effect, no evidence for an overall dose effect was identified (likelihood ratio test, p=0.34).

CONCLUSION

No evidence of a dose-response relationship with iNO was found in this study of very preterm infants with respiratory failure.

Neonatal Ventilation With Inhaled Nitric Oxide Versus Ventilatory Support Without Inhaled Nitric Oxide for Preterm Infants With Severe Respiratory Failure: the INNOVO multicentre randomised controlled trial (ISRCTN 17821339)

BACKGROUND

Although inhaled nitric oxide (iNO) may be a promising treatment for newborn infants with severe respiratory failure, the results from 3 previous small trials were inconclusive.

METHODS

Infants of <34 weeks' gestation, <28 days old, and with severe respiratory failure requiring ventilatory support were randomized to receive or not receive iNO. The study was not blinded.

FINDINGS

Recruited were 108 infants (55 allocated to receive iNO and 53 not allocated to receive iNO) from 15 neonatal units in the United Kingdom and Republic of Ireland. Fifty-nine percent (64 of 108) died, and 84% of the survivors (37 of 44) had signs of some impairment or disability, 9 (20%) of them classified as severely disabled. There was no evidence of an effect of iNO on the primary outcomes: death or severe disability at 1 year corrected age (relative risk [RR]: 0.99; 95% confidence interval [CI]: 0.76 to 1.29); death or supplemental oxygen on expected date of delivery (RR: 0.84; 95% CI: 0.68 to 1.02); or death or supplemental oxygen at 36 weeks' postmenstrual age (RR: 0.98; 95% CI: 0.87 to 1.12). There was a trend for infants allocated to the iNO group to spend more time on the ventilator (log rank: 3.6), on supplemental oxygen (log rank: 1.4), and in hospital (log rank: 3.5) than those allocated to receive no iNO. This pattern predominantly reflected the infants who died. Mean total costs at 1 year corrected age were significantly higher in the iNO group, partly because of the costs of the gas but mainly because of the difference in initial hospitalization costs.

INTERPRETATION

Evidence of prolongation of intensive care and increased costs of such care, without clear beneficial effects, implies that iNO cannot be recommended for preterm infants with severe hypoxic respiratory failure.

Virtual state scattering with cold electrons: para-xylene and para-difluorobenzene

The scattering of electrons with kinetic energies down to a few meV by para-xylene and para-difluorobenzene has been observed experimentally with an electron beam energy resolution of 0.95 to 1.5 meV (full width half maximum). At low electron energies the collisions can be considered as cold scattering events because the de Broglie wavelength of the electron is considerably larger than the target dimensions. The scattering cross sections measured rise rapidly at low energy due to virtual state scattering. The nature of this scattering process is discussed using s- and p-wave phase shifts derived from the experimental data. Scattering lengths are derived of, respectively, -9.5+/-0.5 and -8.0+/-0.5 a.u. for para-xylene and para-difluorobenzene. The virtual state effect is interpreted in terms of nuclear diabatic and partially adiabatic models, involving the electronic and vibronic symmetries of the unoccupied orbitals in the target species. The concept of direct and indirect virtual state scattering is introduced, through which the present species, in common with carbon dioxide and benzene, scatter through an indirect virtual state process, whereas other species, such as perfluorobenzene, scatter through a direct process.

The determination of absolute anion formation cross sections from electron beam scattering data

Using recent low energy electron scattering data for CCl4 and SF6, and accompanying theory illustrating the coupling of attachment and elastic scattering, absolute cross sections are derived for electron attachment to CCl4 and SF6 between impact energies, respectively, of 8-52 meV and 7-42 meV. Values of attachment cross sections are compared with those obtained by laser and threshold photoionization techniques, which include normalization to rate coefficient data. Excellent agreement with the latest CCl4 data is obtained, with less precise agreement for SF6, but still lying within experimental uncertainties.

Importance of Surface Morphology in Interstellar H 2 Formation

Detailed laboratory experiments on the formation of HD from atom recombination on amorphous solid water films show that this process is extremely efficient in a temperature range of 8 to 20 kelvin, temperatures relevant for H2 formation on dust grain surfaces in the interstellar medium (ISM). The fate of the 4.5 electron volt recombination energy is highly dependent on film morphology. These results suggest that grain morphology, rather than the detailed chemical nature of the grain surface, is most important in determining the energy content of the H2 as it is released from the grain into the ISM.

Correlates of specific childhood feeding problems

OBJECTIVE

The correlates of specific childhood feeding problems are described to further examine possible predisposing factors for feeding problems. We report our experience with 349 participants evaluated by an interdisciplinary feeding team.

METHODS

A review of records was conducted and each participant was identified as having one or more of five functionally defined feeding problems: food refusal, food selectivity by type, food selectivity by texture, oral motor delays, or dysphagia. The prevalence of predisposing factors for these feeding problems was examined. Predisposing factors included developmental disabilities, gastrointestinal problems, cardiopulmonary problems, neurological problems, renal disease and anatomical anomalies.

RESULTS

The frequencies of predisposing factors varied by feeding problem. Differences were found in the prevalence of the five feeding problems among children with three different developmental disabilities: autism, Down syndrome and cerebral palsy. Gastro-oesophageal reflux was the most prevalent condition found among all children in the sample and was the factor most often associated with food refusal. Neurological conditions and anatomical anomalies were highly associated with skill deficits, such as oral motor delays and dysphagia.

CONCLUSIONS

Specific medical conditions and developmental disabilities are often associated with certain feeding problems. Information concerning predisposing factors of feeding problems can help providers employ appropriate primary, secondary and tertiary prevention measures to decrease the frequency or severity of some feeding problems.

Pilot investigation of hypothermia in neonates receiving extracorporeal membrane oxygenation

BACKGROUND

Infants requiring extracorporeal membrane oxygenation (ECMO) support represent a high risk group in terms of cerebral injury. Mild hypothermia both during and after cerebral hypoxic ischaemia appears to be a promising strategy for offering neuroprotection.

OBJECTIVE

To investigate whether mild hypothermia was both feasible and safe in infants receiving ECMO as a prelude to any formal assessment of this approach in a randomised trial.

METHODS

Twenty infants (body weight less than 5 kg) with severe cardiopulmonary insufficiency, referred for ECMO support at Glenfield Hospital, Leicester, were enrolled in this study. Twenty consecutive infants (compromising four groups of five) were studied. Baseline data were obtained from a control group who were run throughout their course at 37 degrees C. The patients in the next group were managed with a core temperature of 36 degrees C for the first 12 hours of their ECMO run, before being warmed up to 37 degrees C. After successful completion, the next group of five were cared for at 35 degrees C for the first 12 hours, and, there having been no previous complications, the final group were cared for at 34 degrees C for the first 12 hours. Patients were assessed clinically and biologically. In addition to routine laboratory tests, cytokines (interleukin 6, interleukin 8, tumour necrosis factor alpha, and C reactive protein) were measured and coagulation tests (D-dimer, thrombin-antithrombin III complex, plasmin-alpha(2)-antiplasmin complex) were performed serially for five days.

RESULTS

There were no significant differences among the four groups in gestational age, birth weight, age at the time of ECMO, Apgar scores at one and five minutes, pH before cannulation, oxygenation index, duration of ECMO, and survival rate to discharge from hospital. No adverse effects of mild hypothermia were found on patient management during ECMO. Laboratory data for up to five days of ECMO also showed no difference among the four groups.

CONCLUSION

Mild hypothermia (34 degrees C) for the initial 12 hours of an ECMO run is feasible.

Reaction and scattering in cold electron collisions

Experimental data are presented for the scattering of electrons by CCl4 between 8 and 200 meV impact energy. These results are used in conjunction with data for the reactive process, yielding Cl-, to study the low energy behavior of a system which simultaneously displays both reactive and elastic scattering channels. Phase shifts are derived and illustrate how channel competition develops as the energy falls. This behavior and the involvement of vibronic effects at impact energies above approximately 30 meV pose a challenge to theory.

Extreme prematurity in the UK and Denmark: population differences in viability

BACKGROUND

Previous studies comparing different models of neonatal intensive care have generally not been population based. The objective of this study was to compare the perinatal services of two total populations.

METHODS

Observational study based on two geographically defined populations: the whole of Demark (some centralisation of neonatal intensive care but most delivered locally by small perinatal centres-48 in total) and the Trent Health Region of the UK (no formal centralisation however deliveries almost all focussed on 16 major hospitals with > 90% of the intensive care provided by 13 hospitals). Information was recorded about the course of every liveborn infant < 28 weeks gestation and or < 1000g birth weight and > or = 21 weeks gestation in 1994 and 1995.

RESULTS

Despite having a smaller population the number of liveborn children meeting the study criteria was significantly higher in Trent (Demark 461 (3.3 per 1000 births, 95% confidence interval (CI) 3.0 to 3.6); Trent 572 (4.9 per 1000 births, 95% CI 4.5 to 5.3)). In Denmark 91.1% of these infants were admitted for intensive care and 85.5% in Trent. Despite significantly more Trent infants being exposed to antenatal steroids their outcome was worse (median Clinical Risk Index for Babies (CRIB) score 7 v 4; proportion receiving ventilation 87.6% v 40.0%; survival to discharge (uncorrected for disease severity) 42.3% v 35.0%).

CONCLUSION

The population characteristics of Trent seemed to produce a higher prematurity rate compared to Denmark. These infants as a group appeared sicker and, despite more intensive care delivered by a more specialised service, outcomes were worse.

A confidential enquiry into cases of neonatal encephalopathy

OBJECTIVES

To assess the quality of care and timing of possible asphyxial events for infants with neonatal encephalopathy; to compare the quality of care findings with those relating to the deaths from the Confidential Enquiry into Stillbirths and Deaths in Infancy (CESDI); and to assess whether the confidential enquiry method is a useful clinical governance tool for investigating morbidity.

DESIGN

Independent, anonymised, multidisciplinary case reviews.

SETTING

Trent Health Region, UK.

PATIENTS

All cases of grade II and III neonatal encephalopathy born in 1997, excluding those due to congenital malformation, inborn error of metabolism, or infection. All CESDI deaths thought to have resulted from intrapartum asphyxia in 1996 and 1997.

MAIN MEASURES

Quality of care provided, timing of possible asphyxial episodes, and the source and timing of episodes of suboptimal care.

RESULTS

Significant or major episodes of suboptimal care were identified for 64% of the encephalopathy cases and 75% of the deaths. An average of 2.8 and 2.5 episodes of suboptimal care were identified for the deaths and encephalopathy cases respectively. Over 90% of episodes involved the care provided by health professionals. Results were fed directly back to the units concerned on request and changes in practice have been reported.

CONCLUSIONS

The findings were very similar for the encephalopathy cases and the deaths. We have demonstrated that with minor adaptations the CESDI process can be applied to serious cases of morbidity. However, explicit quality standards, control data, and a more formal mechanism for the implementation of findings would strengthen the confidential enquiry process as part of clinical governance.

Giant resonances in cold electron scattering by CS(2)

Experimental data are presented for the scattering of cold electrons by CS2, for both integral and backward scattering, between a few meV and a few hundred meV impact energy. Giant resonances with cross sections in excess of 50 A(2) are observed below 100 meV, associated with the transient formation of CS(-)(2) at 15 meV and with the bend and symmetric stretch of CS(2) at thresholds of 49 and 82 meV, respectively. The resonance at 49 meV is 2 orders of magnitude greater in cross section than a dipole impulsive model predicts. These structures are superimposed on a sharp rise in the scattering cross section at low energy, which may be attributed to virtual state scattering.

Fibroblast mitogenic activity of lung lavage fluid from infants with chronic lung disease of prematurity

BACKGROUND

Lung fibrosis is thought to be important in chronic lung disease of prematurity (CLD).

METHODS

Fibroblast proliferative activity was assessed in 207 bronchoalveolar lavage fluid (BALF) samples from 43 infants. Sixteen developed CLD (birth weight 765 g (630-1230), gestation 26.5 weeks (23-29)), 18 developed respiratory distress syndrome (RDS) (birth weight 1415 g (430-4160), gestation 31 weeks (23-39)), and nine control infants (birth weight 2110 g (900-3720), gestation 32 weeks (26-41)) received mechanical ventilation for non-pulmonary reasons.

RESULTS

The fibroblast proliferative activity relative to 10% fetal calf serum was 64-75% in infants with CLD, 55-86% in the RDS group, and 42-68% in control infants during the first 5 weeks of life. Only at day 3 was there a difference between the groups (CLD 72% v control 42%, p < 0.01; RDS 63% v control 42%, p < 0.05). With the use of neutralising antibodies, platelet derived growth factor BB (PDGF-BB) and epidermal growth factor were undetectable, and insulin-like growth factor I (IGF-I) accounted for 14% (p < 0.05) and 11% (p < 0.005) of BALF mitogenic activity from the RDS and CLD groups respectively.

CONCLUSIONS

The mitogenic activity of BALF was similar in the three groups studied and was only partially accounted for by IGF-I. Growth factors other than PDGF-BB and IGF-I contribute significantly to this process.

Central venous and bladder pressure reflect transdiaphragmatic pressure during pressure support ventilation

STUDY OBJECTIVES

To determine whether the change in bladder pressure (Pblad) and central venous pressure (Pcvp) may reflect the changes in esophageal pressure (Pes) and gastric pressure (Pgas) when inspiratory pressure support (IPS) is altered.

DESIGN

Prospective clinical study.

SETTING

The ICUs of a teaching hospital.

PATIENTS

Ten patients currently receiving IPS ventilation via a tracheostomy or an endotracheal tube who already had bladder and central venous catheters in situ.

MEASUREMENTS AND RESULTS

Airway pressure, Pes, Pgas, Pcvp, Pblad, and flow were measured at the original IPS setting. IPS then was reduced by 5-cm H(2)O increments until IPS was zero or was at the minimum pressure that could be tolerated by each patient. At each level of IPS, pressures and flow were measured at steady-state breathing. The maximum pressure difference for each pressure during inspiration was calculated. We found that the Delta Pblad correlated closely with the Delta Pgas (r = 0.904) and that the Delta Pes correlated with the Delta Pcvp (r = 0.951). When the Delta Pcvp - Delta Pblad was compared with the transdiaphragmatic pressure for each patient as the IPS was altered, the correlation coefficients varied from 0.952 to 0.999.

CONCLUSION

Although absolute values for the Delta Pcvp during mechanical ventilation do not always reflect the Delta Pes, useful information can be obtained from this route. In individual patients, the two sites of measurement followed each other when IPS was changed, enabling a bedside assessment of the response to reducing respiratory support.

Extracorporeal membrane oxygenation for severe respiratory failure in newborn infants

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is a complex procedure of life support in severe but potentially reversible respiratory failure, used particularly in mature newborn infants. Although the number of babies requiring ECMO is small, and the ECMO policy invasive and potentially expensive, its benefits may be high.

OBJECTIVES

To determine whether ECMO used for neonatal infants with severe respiratory failure is clinically effective and cost-effective compared to a policy of conventional ventilatory support.

SEARCH STRATEGY

The Cochrane Neonatal Group Specialised Register, the Cochrane Controlled Trials Register, and MEDLINE were searched for 1974 to 2001.

SELECTION CRITERIA

All randomised trials comparing neonatal ECMO to conventional ventilatory support.

DATA COLLECTION AND ANALYSIS

The authors independently evaluated the trials for methodological quality and appropriateness for inclusion in the Review (without consideration of their results), and then independently extracted the data.

MAIN RESULTS

The three trials from the USA and one from the UK recruited clinically similar groups of babies. Two trials excluded infants with congenital diaphragmatic hernias. In two, transfer for ECMO implied transport over a considerable distance. One study included an economic evaluation. Two trials had follow up information. All except the UK trial had very small numbers of patients. Two of the trials used conventional randomisation with low potential for bias. The other two used less usual designs which have led to difficulties in their interpretation. All four trials showed a strong benefit of ECMO on mortality (RR 0.44; 95% CI 0.31 to 0.61), especially for babies without congenital diaphragmatic hernia (RR 0.33, 95% CI 0.21 to 0.53). Only the UK trial provided information about death or disability at one and four years, and showed benefit of ECMO at one year (RR 0.56, 95% CI 0.40 to 0.78), and at four years (RR 0.62, 95% CI 0.45 to 0.86). Overall nearly half of the children had died or were severely disabled at four years of age, reflecting the severity of their underlying conditions. Based on economic analysis from the UK trial, the ECMO policy is as cost-effective as other intensive care technologies in common use.

REVIEWER'S CONCLUSIONS

A policy of using ECMO in mature infants with severe but potentially reversible respiratory failure would result in significantly improved survival without increased risk of severe disability amongst survivors. For babies with diaphragmatic hernia ECMO offers short term benefits but the overall effect of employing ECMO in this group is not clear. Further studies are needed to refine ECMO techniques; to consider the optimal timing for introducing ECMO; to identify which infants are most likely to benefit; and to address the longer term implications of neonatal ECMO during later childhood and adult life.