A review of international clinical practice guidelines for the use of oxygen in the delivery room resuscitation of preterm infants

AIM

To collate and assess international clinical practice guidelines (CPG) to determine current recommendations guiding oxygen management for respiratory stabilisation of preterm infants at delivery.

METHODS

A search of public databases using the terms 'clinical practice guidelines', 'preterm', 'oxygen' and 'resuscitation' was made and complemented by direct query to consensus groups, resuscitation expert committees and clinicians. Data were extracted to include the three criteria for assessment: country of origin, gestation and initial FiO₂ and target SpO₂ for the first 10 minutes of life.

RESULTS

A total of 45 CPGs were identified: 36 provided gestation specific recommendations (<28 to <37 weeks) while eight distinguished only between 'preterm' and 'term'. The most frequently recommended initial FiO₂ were between 0.21 and 0.3 (n = 17). Most countries suggested altering FiO₂ to meet SpO₂ targets recommended by expert committees, However, specific five-minute SpO₂ targets differed by up to 20% (70-90%) between guidelines. Five countries did not specify SpO₂ targets.

CONCLUSION

CPG recommendations for delivery room oxygen management of preterm infants vary greatly, particularly in regard to gestational ages, initial FiO₂ and SpO₂ targets and most acknowledge the lack of evidence behind these recommendations. Sufficiently large and well-designed randomised studies are needed to inform on this important practice.

Resuscitating preterm infants with 100% oxygen is associated with higher oxidative stress than room air

AIM

The starting fraction of inspired oxygen for preterm resuscitation is a matter of debate, and the use of room air in full-term asphyxiated infants reduces oxidative stress. This study compared oxidative stress in preterm infants randomised for resuscitation with either 100% oxygen or room air titrated to internationally recommended levels of preductal oxygen saturations.

METHODS

Blood was collected at birth, two and 12 hours of age from 119 infants <32 weeks of gestation randomised to resuscitation with either 100% oxygen (n = 60) or room air (n = 59). Oxidative stress markers, including advanced oxidative protein products (AOPP) and isoprostanes (IsoP), were measured with high-performance liquid chromatography and mass spectrometry.

RESULTS

Significantly higher levels of AOPP were found at 12 hours in the 100% oxygen group (p < 0.05). Increases between two- and 12-hour AOPP (p = 0.004) and IsoP (p = 0.032) concentrations were significantly higher in the 100% oxygen group.

CONCLUSION

Initial resuscitation with room air versus 100% oxygen was associated with lower protein oxidation at 12 hour and a lower magnitude of increase in AOPP and IsoP levels between two and 12 hours of life. Correlations with clinical outcomes will be vital to optimise the use of oxygen in preterm resuscitation.

Clinical use of lactoferrin in preterm neonates: an update

Sepsis-related morbidity and mortality is an increasing concern in all neonatal intensive care units, with reported incidences that are dramatically high regardless of the improvements in the quality of neonatal assistance. Antimicrobial resistance is also becoming a global and regional threat to public health. Neonatal sepsis include bloodstream, urine, cerebrospinal, peritoneal infections, and are classified as early-onset (occurring <3 days of life, EOS) and late-onset sepsis (LOS), i.e., infections arising after the perinatal period. Whereas prevention of EOS relies mainly on maternal-perinatal policies, attempts to reduce LOS incidence are a task merely for neonatologists but are hampered by non-specific clinical features, inadequate sensitivity of diagnostic tests, and late recognition. The frequent occurrence of late neurodevelopmental impairment after LOS challenges neonatologists to seek effective preventative strategies rather than more efficacious antibiotics for treatment. In the area of prevention, consistent evidence is accumulating on fluconazole--for prevention of fungal LOS--and, more recently, on bovine lactoferrin for prevention of both bacterial and fungal LOS: this innate immune system glycoprotein plays an important role in "in vivo" host defenses, and has been shown effective in a multicenter RCT recently published on VLBW neonates. Future studies are warranted to better elucidate the extent of the prevention provided by Ictoferrin and to identify the most suitable dosages to be administered.

Geographically based investigation of the influence of very-preterm births on routine mortality statistics from the UK and Australia

BACKGROUND

Comparisons of national perinatal and neonatal mortality often neglect the underlying causes.

OBJECTIVE

To assess effects of very-preterm births in the UK and Australia.

SETTING

Two geographically defined populations: the former Trent Health Region of the UK and New South Wales (NSW)/the Australian Capital Territory (ACT), Australia.

METHOD

All births 22(+0) to 31(+6) weeks in 2000, 2001 and 2002 were identified by established surveys of perinatal care. Rates of birth and death were compared.

RESULTS

The population of NSW/ACT was 35% higher and there were 66% more births than in Trent (273 495 vs 164 824). The proportion of liveborn infants between 22 and 31 weeks gestation was about 25% higher in Trent (NSW/ACT 2945, rate per 1000 live births 10.82 (95% CI 10.43 to 11.22); Trent 2208, rate per 1000 live births 13.47 (95% CI 12.92 to 14.05)). The proportion of these infants admitted to a neonatal unit was also higher in Trent (91.2% vs 94.4%; OR 1.63 (95% CI 1.30 to 2.05)). Unadjusted mortality in infants admitted to a neonatal unit was similar: NSW/ACT 332/2686 (12.4%); Trent 284/2085 (13.6%); unadjusted OR 1.12 (95% CI 0.94 to 1.33; p = 0.21).

CONCLUSIONS

The higher rates of very premature birth and more ready admission to neonatal intensive care for infants in the UK may help to explain why perinatal and neonatal mortality are higher there than in Australia. Efforts to understand why the rate of premature birth in the UK is so high should be a national priority.

Cooling for newborns with hypoxic ischaemic encephalopathy

BACKGROUND

Newborn animal studies and pilot studies in humans suggest that mild hypothermia following peripartum hypoxia-ischaemia in newborn infants may reduce neurological sequelae without adverse effects.

OBJECTIVES

To determine the effect of therapeutic hypothermia in encephalopathic asphyxiated newborn infants on mortality, long-term neurodevelopmental disability and clinically important side effects.

SEARCH STRATEGY

The standard search strategy of the Neonatal Review Group as outlined in The Cochrane Library (Issue 2, 2007) was used. Randomised controlled trials evaluating therapeutic hypothermia in term newborns with hypoxic ischaemic encephalopathy were identified by searching the Oxford Database of Perinatal Trials, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2007), MEDLINE (1966 to June 2007), previous reviews including cross-references, abstracts, conferences, symposia proceedings, expert informants and journal hand searching.

SELECTION CRITERIA

Randomised controlled trials comparing the use of therapeutic hypothermia with standard care in encephalopathic newborn infants with evidence of peripartum asphyxia and without recognisable major congenital anomalies were included. The primary outcome measure was death or long-term major neurodevelopmental disability. Other outcomes included adverse effects of cooling and 'early' indicators of neurodevelopmental outcome.

DATA COLLECTION AND ANALYSIS

Three review authors independently selected, assessed the quality of and extracted data from the included studies. Authors were contacted for further information. Meta-analyses were performed using relative risk and risk difference for dichotomous data, and weighted mean difference for continuous data with 95% confidence intervals.

MAIN RESULTS

Eight randomised controlled trials were included in this review, comprising 638 term infants with moderate/ severe encephalopathy and evidence of intrapartum asphyxia. Therapeutic hypothermia resulted in a statistically significant and clinically important reduction in the combined outcome of mortality or major neurodevelopmental disability to 18 months of age [typical RR 0.76 (95% CI 0.65, 0.89), typical RD -0.15 (95% CI -0.24, -0.07), NNT 7 (95% CI 4, 14)]. Cooling also resulted in statistically significant reductions in mortality [typical RR 0.74 (95% CI 0.58, 0.94), typical RD -0.09 (95% CI -0.16, -0.02), NNT 11 (95% CI 6, 50)] and in neurodevelopmental disability in survivors [typical RR 0.68 (95% CI 0.51, 0.92), typical RD -0.13 (95% CI -0.23, -0.03), NNT 8 (95% CI 4, 33)]. Some adverse effects of hypothermia included an increase in the need for inotrope support of borderline significance and a significant increase in thrombocytopaenia.

AUTHORS' CONCLUSIONS

There is evidence from the eight randomised controlled trials included in this systematic review (n = 638) that therapeutic hypothermia is beneficial to term newborns with hypoxic ischaemic encephalopathy. Cooling reduces mortality without increasing major disability in survivors. The benefits of cooling on survival and neurodevelopment outweigh the short-term adverse effects. However, this review comprises an analysis based on less than half of all infants currently known to be randomised into eligible trials of cooling. Incorporation of data from ongoing and completed randomised trials (n = 829) will be important to clarify the effectiveness of cooling and to provide more information on the safety of therapeutic hypothermia, but could also alter these conclusions. Further trials to determine the appropriate method of providing therapeutic hypothermia, including comparison of whole body with selective head cooling with mild systemic hypothermia, are required.

Moderately premature infants at Kaiser Permanente Medical Care Program in California are discharged home earlier than their peers in Massachusetts and the United Kingdom

OBJECTIVE

To compare gestational age at discharge between infants born at 30-34(+6) weeks gestational age who were admitted to neonatal intensive care units (NICUs) in California, Massachusetts, and the United Kingdom.

DESIGN

Prospective observational cohort study.

SETTING

Fifty four United Kingdom, five California, and five Massachusetts NICUs.

SUBJECTS

A total of 4359 infants who survived to discharge home after admission to an NICU.

MAIN OUTCOME MEASURES

Gestational age at discharge home.

RESULTS

The mean (SD) postmenstrual age at discharge of the infants in California, Massachusetts, and the United Kingdom were 35.9 (1.3), 36.3 (1.3), and 36.3 (1.9) weeks respectively (p = 0.001). Compared with the United Kingdom, adjusted discharge of infants occurred 3.9 (95% confidence interval (CI) 1.4 to 6.5) days earlier in California, and 0.9 (95% CI -1.2 to 3.0) days earlier in Massachusetts.

CONCLUSIONS

Infants of 30-34(+6) weeks gestation at birth admitted and cared for in hospitals in California have a shorter length of stay than those in the United Kingdom. Certain characteristics of the integrated healthcare approach pursued by the health maintenance organisation of the NICUs in California may foster earlier discharge. The California system may provide opportunities for identifying practices for reducing the length of stay of moderately premature infants.

Relationship between probable nosocomial bacteraemia and organisational and structural factors in UK neonatal intensive care units

OBJECTIVES

To assess the relationship between organisational and structural factors of UK neonatal intensive care units (NICUs) with risk adjusted probable nosocomial bacteraemia.

DESIGN OF STUDY

A prospective observational study of infants concurrently admitted to 54 randomly selected UK NICUs between March 1998 and April 1999.

RESULTS

Of the 13 334 infants admitted, 402 (2.97%) had probable nosocomial bacteraemia. The median unit level percentage of infants with probable nosocomial bacteraemia was 2.48% (minimum 0%, maximum 9%). The risk adjusted odds of probable nosocomial bacteraemia were increased by 1.13 (95% CI 1.07 to 1.20) for each additional level 1 cot per hand washbasin and decreased by 0.53 (95% CI 0.35 to 0.79) in infants admitted to units with an NICU infection control nurse compared with units without. There was no relation with an increase in the floor space of the unit per cot (odds ratio 0.99 (95% CI 0.98 to 1.00) per m(2)) or with the quality of hand washing signs (odds ratio 1.04 (95% CI 0.93 to 1.16) per increase in quality score).

CONCLUSIONS

There is widespread variation in rates of probable nosocomial bacteraemia in UK NICUs. Probable nosocomial bacteraemia is reduced in units with a dedicated infection control nurse and with the presence of more hand washbasins. Further research is required to identify methods to eliminate nosocomial bacteraemia.

The effect of prepartum antibiotics on the type of neonatal bacteraemia: insights from the MRC ORACLE trials

We analysed the type of bacteraemia before discharge from Neonatal Intensive Care Units in babies born to women randomised to the MRC ORACLE Trials. There was no evidence for an effect of oral antibiotics given prior to delivery on bacteraemia due to gram negative or enterococci bacteria, but Group B streptococcal (GBS) bacteraemia was significantly reduced in women with preterm prelabour rupture of the membranes (1.58% to 0.55%, relative risk 0.34; 95% CI: 0.17-0.70). There was no detectable effect in women in spontaneous preterm labour with intact membranes as the risk of GBS bacteraemia in their babies was very small regardless of treatment.

Relationship between Changes in Thymic Emigrants and Cell-Associated HIV-1 Dna in HIV-1-Infected Children Initiating Antiretroviral Therapy

Objectives and methods

To investigate the relationship between cell-associated HIV-1 dynamics and recent thymic T-cell emigrants, HIV-1 DNA and T-cell receptor rearrangement excision circles (TREC, a marker of recent thymic emigrants) were measured in peripheral blood mononuclear cells in 181 samples from 33 HIV-1-infected children followed for 96 weeks after antiretroviral therapy (ART) initiation.

Results

At baseline, HIV-1 DNA was higher in children with higher TREC ( P=0.02) and was not related to age, CD4 or HIV-1 RNA in multivariate analyses ( P>0.3). Overall, TREC increased and HIV-1 DNA decreased significantly after ART initiation, with faster HIV-1 DNA declines in children with higher baseline TREC ( P=0.009). The greatest decreases in HIV-1 DNA occurred in children with the smallest increases in TREC levels during ART ( P=0.002). However, this inverse relationship between changes in HIV-1 DNA and TREC tended to vary according to the phase of HIV-1 RNA decline ( P=0.13); for the same increase in TREC, HIV-1 DNA decline was much smaller during persistent or transient viraemia compared with stable HIV-1 RNA suppression.

Conclusions

Overall, these findings indicate that TREC levels predict HIV-1 DNA response to ART and suggest that immune repopulation by thymic emigrants adversely affects HIV-1 DNA decline in the absence of persistent viral suppression, possibly by providing a cellular source for viral infection and replication.

Can polyclonal intravenous immunoglobulin limit cytokine mediated cerebral damage and chronic lung disease in preterm infants?

Recent evidence suggests that inflammatory cytokines may play an important role in cerebral and pulmonary injury, especially in preterm infants. Immunomodulatory agents may help to limit such injury by reducing inflammation. Immunoglobulin has multiple anti-inflammatory properties and can modulate the inflammatory cytokine response. New evidence is required to test the hypotheses that prophylaxis or treatment with intravenous immunoglobulin may limit such inflammatory damage.

ORACLE--antibiotics for preterm prelabour rupture of the membranes: short-term and long-term outcomes

Preterm prelabour rupture of the foetal membranes (pPROM) is the most common antecedent of preterm birth and can lead to death, neonatal disease and long-term disability. Previous small trials of antibiotics for pPROM suggested some health benefits for the neonate, but the results were inconclusive. A large, randomized, multicentre trial was undertaken to try to resolve this issue. In total, 4826 women with pPROM were randomized to one of four treatments: 325 mg co-amoxiclav plus 250 mg erythromycin, co-amoxiclav plus erythromycin placebo, erythromycin plus co-amoxiclav placebo, or co-amoxiclav placebo plus erythromycin placebo, four times daily for 10 d or until delivery. The primary outcome measure was a composite of neonatal death, chronic lung disease or major cerebral abnormality on ultrasonography before discharge from hospital. The analysis was undertaken by intention to treat. Indications of short-term respiratory function, chronic lung disease and major neonatal cerebral abnormality were reduced with the prescription of erythromycin. In contrast, the use of co-amoxiclav was associated with a significant increase in the occurrence of neonatal necrotizing enterocolitis.

CONCLUSION

Prophylactic antibiotics can play a role in preterm prelabour rupture of the membranes in reducing infant morbidity.

Supplemental oxygen for the treatment of prethreshold retinopathy of prematurity

BACKGROUND

Oxygen has long been implicated in the pathogenesis of retinopathy of prematurity (ROP) and is rigorously monitored in today's neonatal intensive care units. Recent research using a feline model has shown an improvement in ROP outcome of kittens treated with supplemental oxygen. Current treatment for ROP by retinal ablation is not without complications so a non-invasive method of treatment is preferred. The possible effects of long term oxygen supplementation on chronic lung disease, length of hospital stay and growth and development are, however, unknown.

OBJECTIVES

To determine whether, in preterm or low birth weight infants with prethreshold ROP, targeting higher as compared to normal transcutaneous oxygen levels or pulse oximetry levels when using supplemental oxygen reduces the progression of ROP to threshold disease and improves visual outcome without any adverse effects.

SEARCH STRATEGY

The standard search strategy of the Cochrane Neonatal Review Group was used. This included searches of the Oxford Database of Perinatal Trials, MEDLINE, previous reviews including cross references, abstracts, conferences and symposia proceedings, expert informants and journal handsearching. An additional literature search of the MEDLINE (1966-June 2002), EMBASE (1980-April 2002), and CINAHL (1982-April 2002) databases was conducted in order to locate any trials in addition to those provided by the Cochrane Controlled Trials Register (CENTRAL/CCTR, The Cochrane Library Issue 2, 2002).

SELECTION CRITERIA

All randomised or quasi randomised studies comparing higher versus normal target oxygen levels in preterm or low birthweight infants with prethreshold ROP were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

The methodological quality of the one eligible trial was assessed independently by two authors for the degree of selection, performance, attrition and detection bias. Data regarding clinical outcomes including progression to threshold ROP, blindness or severe visual impairment, mortality, respiratory morbidities and long term growth were extracted and reviewed independently by two authors. Results were compared and differences resolved as required. Data analysis was conducted according to the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

The one trial included in this review enrolled 649 infants. There was a trend for supplemental oxygen to reduce the progression to threshold ROP, however this did not reach statistical significance (RR 0.84, 95% CI 0.70, 1.02). A subgroup analysis of those infants without plus disease showed significantly fewer infants progressing to threshold ROP in infants treated with supplemental oxygen. However this analysis was not pre-specified so these results should be interpreted with caution. No significant effects were detected on blindness or severe visual function at three months corrected age, mortality, pneumonia, chronic lung disease or weight gain. Adverse pulmonary events were more common in the higher oxygen saturation group and these infants were in hospital and on supplemental oxygen for longer. Longer term visual outcomes were not reported.

REVIEWER'S CONCLUSIONS

The results of this systematic review do not show a statistically significant reduction in the rate of progression to threshold ROP with supplemental oxygen treatment, but reveal increased adverse pulmonary sequelae with higher oxygen targeting in this group of preterm infants. Future research needs to be directed towards the question of whether infants without plus disease are more likely to respond to supplemental oxygen therapy than those with plus disease.

Cooling for newborns with hypoxic ischaemic encephalopathy

BACKGROUND

Newborn animal and human pilot studies suggest that mild hypothermia following peripartum hypoxia-ischaemia in newborn infants may reduce neurological sequelae, without adverse effects.

OBJECTIVES

To determine whether therapeutic hypothermia in encephalopathic asphyxiated newborn infants reduces mortality and long-term neurodevelopmental disability, without clinically important side effects.

SEARCH STRATEGY

The standard search strategy of the Neonatal Review Group as outlined in the Cochrane Library (Issue 2, 2003) was used. Randomised controlled trials evaluating therapeutic hypothermia in term newborns with hypoxic ischaemic encephalopathy were identified by searching the Oxford Database of Perinatal Trials, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library Issue Issue 2, 2003), MEDLINE (1966 to July 2003), previous reviews including cross-references, abstracts, conferences, symposia proceedings, expert informants and journal hand searching.

SELECTION CRITERIA

Randomised controlled trials comparing the use of therapeutic hypothermia with normothermia in encephalopathic newborn infants with evidence of peripartum asphyxia and without recognisable major congenital anomalies were included. The primary outcome measure was death or long-term major neurodevelopmental disability. Other outcomes included adverse effects of cooling and 'early' indicators of neurodevelopmental outcome.

DATA COLLECTION AND ANALYSIS

Three reviewers independently selected, assessed the quality of and extracted data from the included studies. Authors were contacted for further information. Meta-analyses were performed using relative risk and risk difference for dichotomous data, and weighted mean difference for continuous data with 95% confidence intervals.

MAIN RESULTS

Two randomised controlled trials were included in this review, comprising 50 term infants with moderate/ severe encephalopathy and evidence of intrapartum asphyxia. There was no significant effect of therapeutic hypothermia on the combined outcome of death or major neurodevelopmental disability in survivors followed. No adverse effects of hypothermia on short term medical outcomes or on some 'early' indicators of neurodevelopmental outcome were detected.

REVIEWER'S CONCLUSIONS

Although two small randomised controlled trials demonstrated neither evidence of benefit or harm, current evidence is inadequate to assess either safety or efficacy of therapeutic hypothermia in newborn infants with hypoxic ischaemic encephalopathy. Therapeutic hypothermia for encephalopathic asphyxiated newborn infants should be further evaluated in well designed randomised controlled trials.

Broad-spectrum antibiotics for spontaneous preterm labour: the ORACLE II randomised trial. ORACLE Collaborative Group

BACKGROUND

Preterm birth after spontaneous preterm labour is associated with death, neonatal disease, and long-term disability. Previous small trials of antibiotics for spontaneous preterm labour have reported inconclusive results. We did a randomised multicentre trial to resolve this issue.

METHODS

6295 women in spontaneous preterm labour with intact membranes and without evidence of clinical infection were randomly assigned 250 mg erythromycin (n=1611), 325 mg co-amoxiclav (250 mg amoxicillin and 125 mg clavulanic acid; n=1550), both (n=1565), or placebo (n=1569) four times daily for 10 days or until delivery, whichever occurred earlier. The primary outcome measure was a composite of neonatal death, chronic lung disease, or major cerebral abnormality on ultrasonography before discharge from hospital. Analysis was by intention to treat.

FINDINGS

None of the trial antibiotics was associated with a lower rate of the composite primary outcome than placebo (erythromycin 90 [5.6%], co-amoxiclav 76 [5.0%], both antibiotics 91 [5.9%], vs placebo 78 [5.0%]). However, antibiotic prescription was associated with a lower occurrence of maternal infection.

INTERPRETATION

This trial provides evidence that antibiotics should not be routinely prescribed for women in spontaneous preterm labour without evidence of clinical infection.

Broad-spectrum antibiotics for preterm, prelabour rupture of fetal membranes: the ORACLE I randomised trial. ORACLE Collaborative Group

BACKGROUND

Preterm, prelabour rupture of the fetal membranes (pPROM) is the commonest antecedent of preterm birth, and can lead to death, neonatal disease, and long-term disability. Previous small trials of antibiotics for pPROM suggested some health benefits for the neonate, but the results were inconclusive. We did a randomised multicentre trial to try to resolve this issue.

METHODS

4826 women with pPROM were randomly assigned 250 mg erythromycin (n=1197), 325 mg co-amoxiclav (250 mg amoxicillin plus 125 mg clavulanic acid; n=1212), both (n=1192), or placebo (n=1225) four times daily for 10 days or until delivery. The primary outcome measure was a composite of neonatal death, chronic lung disease, or major cerebral abnormality on ultrasonography before discharge from hospital. Analysis was by intention to treat.

FINDINGS

Two women were lost to follow-up, and there were 15 protocol violations. Among all 2415 infants born to women allocated erythromycin only or placebo, fewer had the primary composite outcome in the erythromycin group (151 of 1190 [12.7%] vs 186 of 1225 [15.2%], p=0.08) than in the placebo group. Among the 2260 singletons in this comparison, significantly fewer had the composite primary outcome in the erythromycin group (125 of 1111 [11.2%] vs 166 of 1149 [14.4%], p=0.02). Co-amoxiclav only and co-amoxiclav plus erythromycin had no benefit over placebo with regard to this outcome in all infants or in singletons only. Use of erythromycin was also associated with prolongation of pregnancy, reductions in neonatal treatment with surfactant, decreases in oxygen dependence at 28 days of age and older, fewer major cerebral abnormalities on ultrasonography before discharge, and fewer positive blood cultures. Although co-amoxiclav only and co-amoxiclav plus erythromycin were associated with prolongation of pregnancy, they were also associated with a significantly higher rate of neonatal necrotising enterocolitis.

INTERPRETATION

Erythromycin for women with pPROM is associated with a range of health benefits for the neonate, and thus a probable reduction in childhood disability. However, co-amoxiclav cannot be routinely recommended for pPROM because of its association with neonatal necrotising enterocolitis. A follow-up study of childhood development and disability after pPROM is planned.

Hospital mortality in relation to staff workload: a 4-year study in an adult intensive-care unit

BACKGROUND

Few studies have examined mortality rates in relation to the workload of hospital staff. We investigated this issue in one adult intensive-care unit (ICU) in the UK.

METHODS

We measured ICU workload per shift during each patient's stay for all admissions between 1992 and 1995 that met criteria for adjustment of mortality risk by the APACHE II equation (n=1050). APACHE II data were validated by one observer. Measures of workload in each patient's stay included occupancy, total ICU nursing requirement as defined by the UK Intensive Care Society, and the ratio of occupied to appropriately staffed beds. Over the period, staffing was appropriate for between 4.1 and 5.3 occupied beds (1.3 nurses per patient).

FINDINGS

There were 337 deaths, 49 more (95% CI 34-65) than predicted by the APACHE II equation. Median occupancy was 5.8 beds, and median nursing requirement was 1.6 per patient. On multiple logistic regression analysis, adjusted mortality was more than two times higher (odds ratio 3.1 [1.9-5.0]) in patients exposed to high than in those exposed to low ICU workload, defined by average nursing requirement per occupied bed and peak occupancy; the unadjusted odds ratio for this comparison was 4.0 (2.6-6.2). After exclusion of measures of nursing requirement, adjusted mortality increased with the ratio of occupied to appropriately staffed beds during each patient's stay. All logistic regression models fitted the data satisfactorily.

INTERPRETATION

Variations in mortality may be partly explained by excess ICU workload. This methodology may have implications for planning and clinical governance.

A cost analysis of neonatal care in the UK: results from a multicentre study. ECSURF Study Group

BACKGROUND

A number of papers have recently been published examining the magnitude of scale economies in neonatal care and the level of activity at which these become attainable. Although these agree there is scope for economies in the production of neonatal care, they debate the extent to which such economies are attainable and how they might best be detected. A major multicentre study of neonatal units in the United Kingdom has produced costing and activity data allowing these issues to be explored afresh.

METHODS

A postal questionnaire was used to determine neonatal cost and activity levels in 57 UK neonatal units. Costs for the financial year 1990-1991 related to clinical staffing, support (such as pathology) and overheads (such as heat, light, power and administrative overheads). Activity related to the total number of care days provided and the number of these that were intensive in nature. All data were scrutinized to ensure consistent definitions. A multivariate regression analysis was used to investigate the relationship between costs and activity.

RESULTS

A double-log function relating variations in total costs to total days, case-mix and an interaction term provided the best fit to the data. The analysis suggests that significant economies of scale are possible within the observed range of provision of intensive care.

CONCLUSIONS

Significant economies of scale may be attainable. Nevertheless, these results should be carefully interpreted. In particular, the costs of neonatal care should not be examined in isolation but in relation to outcomes. In certain instances, units of inefficient scale but acceptable outcome may be defensible on grounds of ease of access.

UK neonatal intensive care services in 1996. On behalf of the UK Neonatal Staffing Study Collaborative Group

A census of activity and staff levels in 1996 was conducted in UK neonatal units and achieved a 100% response from 246 units. Among the 186 neonatal intensive care units, the median (interquartile range) number of total cots was 18(14-22); level 1 intensive care cots 4(2-6); total admissions 318(262-405); very low birthweight admissions 40(28-68); and the number ventilated or given CPAP by endotracheal tube 52(32-83). Forty six (25%) intensive care units lacked the recommended minimum of one consultant with prime responsibility for neonatal medicine. As a conservative estimate 79% of intensive care units had a lower nursing provision than that recommended in previously published guidelines. There was substantial variation in activity and staffing levels among units.

Risk adjustment for quality improvement

We can learn what is achievable with current technologies by comparing our neonatal intensive care unit outcomes with others. Because neonatal intensive care units may vary with respect to their case-mix, risk adjustment is essential to making fair comparisons in any research that does not equalize risks through randomization. Risk adjustment first requires strict definition of each specific outcome. Then each risk factor is measured and weighted accordingly. Severity of illness scores are a special form of risk adjustment. The leading newborn illness severity scores rely on physiology-based items from bedside vital signs and laboratory tests. The mechanics of score development are discussed including item selection, definition, collection, and potential biases. The process of weighting risk factors usually involves building multivariate models. Issues of derivation, validation, discrimination, calibration, and reliability affect the utility of all scores. Once a comparison is appropriately risk-adjusted, there are important cautions about interpretation, including the source of the reference (benchmark) population, sample size, and biases from incomplete risk adjustment. Nonetheless, these findings can spur quality improvement efforts that can lead to dramatic, system-wide improvements in outcomes.

Neonatal risk scoring systems. Can they predict mortality and morbidity?

Physiology-based illness severity scores are proving their value through a wide variety of practical applications. The theoretical disadvantages noted in Table 1 have not turned out to be major problems, whereas the advantages have been quite real. Numerous studies have reported insightful comparisons between treatment groups, between NICUs, between countries, between eras, and over the course of care. Many institutions have implemented routine collection of physiology-based newborn scores. The answer to the question posed in the title is yes; neonatal risk scoring systems can predict some mortality and some morbidity. However, it is clear that this function is much less important than their application as a means of improving quality and cost. Future development will depend on commercially viable applications.

Annual league tables of mortality in neonatal intensive care units: longitudinal study. International Neonatal Network and the Scottish Neonatal Consultants and Nurses Collaborative Study Group

OBJECTIVE

To assess whether crude league tables of mortality and league tables of risk adjusted mortality accurately reflect the performance of hospitals.

DESIGN

Longitudinal study of mortality occurring in hospital.

SETTING

9 neonatal intensive care units in the United Kingdom.

SUBJECTS

2671 very low birth weight or preterm infants admitted to neonatal intensive care units between 1988 and 1994.

MAIN OUTCOME MEASURES

Crude hospital mortality and hospital mortality adjusted using the clinical risk index for babies (CRIB) score.

RESULTS

Hospitals had wide and overlapping confidence intervals when ranked by mortality in annual league tables; this made it impossible to discriminate between hospitals reliably. In most years there was no significant difference between hospitals, only random variation. The apparent performance of individual hospitals fluctuated substantially from year to year.

CONCLUSIONS

Annual league tables are not reliable indicators of performance or best practice; they do not reflect consistent differences between hospitals. Any action prompted by the annual league tables would have been equally likely to have been beneficial, detrimental, or irrelevant. Mortality should be compared between groups of hospitals using specific criteria-such as differences in the volume of patients, staffing policy, training of staff, or aspects of clinical practice-after adjusting for risk. This will produce more reliable estimates with narrower confidence intervals, and more reliable and rapid conclusions.

Predicting outcome in very low birthweight infants using an objective measure of illness severity and cranial ultrasound scanning

AIM

To investigate the feasibility of developing an objective tool for predicting death and severe disability using routinely available data, including an objective measure of illness severity, in very low birthweight babies.

METHOD

A cohort study of 297 premature babies surviving the first three days of life was made. Predictive variables considered included birthweight, gestation, 3 day cranial ultrasound appearances and 3 day CRIB (clinical risk index for babies) score. Models were developed using regression techniques and positive predictive values (PPV) and likelihood ratios (LR) were calculated.

RESULTS

On univariate analysis, birthweight, gestation, 3 day CRIB score and 3 day cranial ultrasound appearances were each associated with death. On multivariate analysis, 3 day CRIB score and 3 day cranial ultrasound appearances remained independently associated. A 3 day CRIB score > 4 along with intraventricular haemorrhage (IVH) grade 3 or 4 was associated with a PPV of 64% and an LR of 9.8 (95% confidence limits 3.5, 27.9). Only 3 day CRIB score and 3 day cranial ultrasound appearances were associated with severe disability on univariate analysis. Both remained independently associated on multivariate analysis. A 3 day CRIB score > 4 along with an IVH grade of 3 or 4 was associated with a PPV of 60% and an LR of 24.2 (95% CI 4.4, 133.3).

CONCLUSION

Incorporating objective measures of illness severity may improve current prediction of death and disability in premature infants.

Measurement properties of the Clinical Risk Index for Babies--reliabilty, validity beyond the first 12 hours, and responsiveness over 7 days

OBJECTIVES

Clinical Risk Index for Babies (CRIB) is a simple instrument used to measure clinical risk and illness severity in very low birth-weight infants. We assessed its reliability, validity beyond the first 12 hrs after birth, and responsiveness to individual change in condition after 7 days.

DESIGN

Cohort study.

SETTING

Three tertiary and three nontertiary UK hospitals.

PATIENTS

Three hundred ninety-eight infants whose birth weight was <1501 g or who were born before a 31-wk gestation period.

INTERVENTIONS

Inter- and intrarater reliability of data extraction were assessed by Pearson and intraclass correlation. To validate CRIB, we tested the correlation between clinical risk and illness severity with the risk of: a) death; b) prolonged treatment with supplemental oxygen; and c) disability at 2 yrs. Logistic regression models were fitted to assess validity and responsiveness.

MEASUREMENTS AND MAIN RESULTS

Reliability coefficients ranged from 0.76 (95% confidence interval, 0.71 to 0.81) to 0.97 (0.94 to 1.00). Throughout the first week, CRIB correlated with the risk of death (p < .001), prolonged treatment with oxygen (p < .001), and disability (p < .001 to p = .033). Improved condition, represented by a reduction in CRIB within the first week, was independently associated with lower risks of each adverse outcome, p < .05.

CONCLUSIONS

During the first week, CRIB was reliable, valid, and responsive. These properties support the use of CRIB in the stratification of infants by risk and illness severity in cohort studies, and they also indicate that CRIB may have the potential to be used in other ways in the future.

What do doctors record in the medical notes following discussion with the parents of sick premature infants?

In a retrospective review of medical notes we determined: (1) how often doctors record discussions with the parents of very low birth weight (VLBW) infants during the neonatal period; (2) what details of any discussion they actually record and; (3) if they are more likely to record discussion with the parents of sicker infants. A random sample (30%) of all VLBW infants admitted between 1989 and 1993 to a regional NICU was reviewed, n = 87. No discussion was documented in 47 cases, one of whom died, 24 had a single episode of discussion recorded and 16 had two or more episodes recorded. Specific discussion about prognosis was only recorded in the notes of 27 babies. Discussion was more likely to be documented in sicker infants as measured by CRIB (clinical risk index for babies) score, t = -3.9, P < 0.001.

CONCLUSION

A record of discussion between medical staff and parents is found in the medical notes of less than half of all VLBW infants. These findings may have practical, ethical and legal implications.

Randomised controlled trial of respiratory system compliance measurements in mechanically ventilated neonates

AIM

To determine whether outcomes of neonatal mechanical ventilation could be improved by regular pulmonary function testing.

METHODS

Two hundred and forty five neonates, without immediately life threatening congenital malformations, were mechanically ventilated in the newborn period. Infants were randomly allocated to conventional clinical management (control group) or conventional management supplemented by regular measurements of static respiratory system compliance, using the single breath technique, with standardised management advice based on the results.

RESULTS

Fifty five (45%) infants in each group experienced one or more adverse outcomes. The median (quartile) durations of ventilation and oxygen supplementation were 5 (2-12) and 6 (2-34) days for the control group, and 4 (2-9) and 6 (3-36) days for the experimental group (not significant). On post-hoc secondary analysis, control group survivors were ventilated for 1269 days with a median (quartile) of 5 (2-13) days, and experimental group survivors were ventilated for 775 days with a median (quartile) duration of 3 (2-8) days (p = 0.03).

CONCLUSIONS

Although primary analysis did not show any substantial benefit associated with regular measurement of static respiratory system compliance, this may reflect a type II error, and a moderate benefit has not been excluded. Larger studies are required to establish the value of on-line monitoring techniques now available with neonatal ventilators.

CRIB (clinical risk index for babies) in relation to nosocomial bacteraemia in very low birthweight or preterm infants

Positive blood cultures in very low birthweight or preterm infants usually reflect bacteraemia, septicaemia, or failure of asepsis during sampling and lead to increased costs and length of stay. Rates of nosocomial, or hospital acquired, bacteraemia may therefore be important indicators of neonatal unit performance, if comparisons are adjusted for differences in initial risk. In a preliminary study the risk of nosocomial bacteraemia was related to initial clinical risk and illness severity measured by the clinical risk index for babies (CRIB). Nosocomial bacteraemia was defined as clinically suspected infection with culture of bacteria in blood more than 48 hours after birth. One or more episodes of nosocomial bacteraemia were identified retrospectively in 36 of 143 (25%) infants in a regional neonatal unit between 1992 and 1994. Biologically plausible models were developed using regression analysis techniques. After correcting for period at risk, nosocomial bacteraemia was independently associated with gestation at birth and CRIB. Death was independently associated with CRIB, but not with nosocomial bacteraemia. CRIB may contribute, with other explanatory variables, to more comprehensive predictive models of death and nosocomial infection. These may facilitate future risk adjusted comparative studies between groups of neonatal units.

A numerical model of an intensive care ventilator-humidifier system

Current intensive care ventilator-humidifier systems neither monitor nor adequately control inspired gas humidity. Problems of low delivered humidity and condensation within ventilator circuitry are commonly encountered. To help to address these problems, a numerical model of a complete ventilator-humidifier-patient intensive care system has been developed. The model, based on a finite difference technique, can predict pressures, flow-rates, temperatures and relative humidities at discrete points throughout the system. A comparison of numerical predictions and measurements in a real system is reported. A strong qualitative agreement is demonstrated in all cases studied, and a good quantitative agreement is obtained in most cases. It is concluded that such models could be used to assess methods of controlling ventilator-humidifier systems to prevent the occurrence of condensation. Similar models could be developed for other medical gas delivery systems.

Phagocyte chemiluminescence in pre-term infants

Intact phagocyte function is a pre-requisite for successful defence against infection, but paradoxically, these cells may also play a major role in the pathogenesis of the infant respiratory distress syndrome. Phagocyte function is known to be deficient in pre-term infants, who are at risk of infection as a result, but these infants are also at risk of respiratory distress syndrome as a result of surfactant deficiency. Despite this, few longitudinal studies of phagocyte function have been performed in pre-term infants. We have used lucigenin-enhanced chemiluminescence to examine the respiratory burst of mixed samples containing polymorphonuclear leucocytes and monocytes of 100 pre-term infants at 48- to 72-h intervals during their admission to a neonatal care unit. Increased polymorphonuclear leucocyte chemiluminescence was associated with respiratory distress syndrome and the use of intermittent positive pressure ventilation. Multiple linear regression analysis revealed a slight, but significant depression of chemiluminescence in association with the use of gentamicin and penicillin when stronger influencing factors such as the presence of respiratory distress syndrome were taken into consideration. Measurement of phagocyte function by sensitive luminescence assays requires very little blood and may be useful in pre-term infants to follow the severity of respiratory distress syndrome. However, it is probable that other factors such as antioxidant capacity also have an important influence on the degree of tissue damage.

CRIB and performance indicators for neonatal intensive care units (NICUs)

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Life-threatening inadvertent positive end-expiratory pressure

Inadvertent positive end-expiratory pressure (PEEP) is a potential cause of lung overdistension and impaired gas exchange in ventilated infants. It can be extremely difficult to diagnose clinically and if unrecognized can be life-threatening. Measurement of lung function can lead to the recognition of inadvertent PEEP, allowing appropriate ventilator adjustment with immediate substantial improvement in clinical state. Lung function measurements can help to optimize ventilation and may improve clinical outcome.

Antibiotic effects on phagocyte chemiluminescence in vitro

Phagocytes are an essential defence against infection. Since drugs which affect their function may alter the outcome of infections, we have studied the effect of nine antibiotics on phagocyte function in vitro. The effects of antibiotics on the respiratory burst function of phagocytes from healthy adult donors were investigated using lucigenin-enhanced chemiluminescence in response to serum-opsonised zymosan. Aminoglycosides showed dose-dependent suppression of polymorphonuclear leucocyte chemiluminescence, except streptomycin which caused enhancement. Erythromycin caused profound suppression of chemiluminescence from both polymorphonuclear leucocytes and monocytes. Benzylpenicillin and the cephalosporins caused variable suppression of phagocyte chemiluminescence: cefotaxime increased monocyte chemiluminescence in some experiments. None of the drugs produced suppression at clinically relevant plasma concentrations, but erythromycin and some other drugs are preferentially concentrated in phagocytes to levels which suppress their oxidative metabolism in vitro. It is therefore possible that some antibiotics alter phagocyte function: ex vivo studies of phagocyte function in patients taking antibiotics would be valuable.

Reliability of clinical assessments of respiratory system compliance (Crs) made by junior doctors

OBJECTIVE

To assess the reliability of estimates of static respiratory system compliance (Crs) made by junior hospital doctors caring for ventilated newborn infants.

DESIGN

A prospective comparison of junior doctors' estimates of Crs to the Crs measured immediately afterwards.

SETTING

A regional neonatal intensive care nursery in Edinburgh, Scotland.

PATIENTS

46 ventilated newborn infants.

MEASUREMENTS AND RESULTS

Crs was estimated by three grades of junior doctor (Senior House Officer, Registrar and Research Fellow) using two different methods, (i) based on visual assessment of tidal volume in relation to inflation pressure (optical Crs) and (ii) directly using a visual analogue scale (analogue Crs). The Crs was then measured immediately afterwards using the single breath passive expiratory flow technique. The differences between the estimates and the measurements were calculated for each grade of observer and plotted against the corresponding measurements. The relationship between estimates and measurements was also expressed in terms of the coefficients of determination r2 calculated by least squares regression. With both methods of estimation observers tended to overestimate the Crs of infants with lower measured Crs and underestimate that of infants with higher measured Crs with many estimates differing from the measurements by more than 50%. Values of r2 ranged from 0.086 to 0.481 indicating a weak relationship between the estimates and the measurements.

CONCLUSIONS

Junior doctors' estimates of Crs were unreliable and did not represent a useful method of assessing respiratory function. The clinical use of compliance measurements merits wider evaluation.

Economics of infection at the extremes of age

People are more vulnerable to infection at the extremes of age for a variety of reasons, the most important being that they are more likely to be in hospital in a crowded ward environment and to be at risk from hospital acquired infection. Recognition of this increased vulnerability to infection should be accompanied by equal emphasis on their increased susceptibility to nosocomial disease arising from the diagnosis or treatment of infection. An economic evaluation of infection at the extremes of age should include an assessment of need made in terms of the capacity of patients to benefit from investigation or treatment. Benefits should not be confused with treatment effects such as reduction in pyrexia or correction of other physiological abnormalities. Ideally benefits should be quantified in a manner which allows comparison with the cost-effectiveness of other uses of health care resources. In order to achieve this aim clinicians must understand the economic terms opportunity cost and marginal cost-effectiveness. These terms are defined in general terms and then applied to examples of investigation, prevention and treatment of infection at the extremes of age.

Static respiratory compliance in the newborn. I: A clinical and prognostic index for mechanically ventilated infants

Accurate measures of the severity of respiratory disease are important, both clinically and epidemiologically. The apparent prognostic value of static respiratory system compliance (Crs) on the first day and mean appropriate fractional inspired oxygen (FIO2) in the first 12 hours of life were compared in 48 infants who received mechanical ventilation in a regional neonatal unit. Their median (range) gestation was 30 (25-41) weeks and they were representative of all 140 newborn infants born to residents of a geographically defined area who received mechanical ventilation over a 30 month period. Using the best cut off value (< or = 0.6 ml/cm H2O/m corrected for body length), static Crs predicted hospital death with 98% accuracy, 80% sensitivity, and 100% specificity. Using the best cut off value (> 0.60), mean FIO2 in the first 12 hours predicted hospital death with 81% accuracy, 80% sensitivity, and 81% specificity. Static Crs appeared to be a more accurate measure of respiratory function and disease severity than mean FIO2, perhaps because static Crs is less dependent on ventilator management than routine indices based on blood gases. Static Crs now merits wider evaluation, both as an aid to routine clinical management and as a prognostic index in comparative studies.

Static respiratory compliance in the newborn. II: Its potential for improving the selection of infants for early surfactant treatment

Static respiratory system compliance (Crs) and lecithin/sphingomyelin (L/S) ratios in tracheal aspirates were estimated in two independent groups of mechanically ventilated infants. Crs was measured rapidly at the cotside using a passive expiratory flow technique and L/S ratios were estimated in the laboratory by high performance liquid chromatography. In the reference group of 22 infants, Crs < 1.8 ml/cm H2O/m predicted surfactant deficiency with a positive predictive value of 100% and a negative predictive value of 92%. In the validation group of 23 infants, Crs < 1.8 ml/cm H2O/m predicted surfactant deficiency with a positive predictive value of 94% and a negative predictive value of 83%. Measurement of static Crs is a rapid, non-invasive technique which may usefully supplement current methods of selecting infants at high risk of respiratory distress syndrome.