Observational cohort study of changing trends in non-invasive ventilation in very preterm infants and associations with clinical outcomes

OBJECTIVE

To determine the change in non-invasive ventilation (NIV) use over time in infants born at <32 weeks' gestation and the associated clinical outcomes.

STUDY DESIGN

Retrospective cohort study using routinely recorded data from the National Neonatal Research Database of infants born at <32 weeks admitted to neonatal units in England and Wales from 2010 to 2017.

RESULTS

In 56 537 infants, NIV use increased significantly between 2010 and 2017 (continuous positive airway pressure (CPAP) from 68.5% to 80.2% in 2017 and high flow nasal cannula (HFNC) from 14% to 68%, respectively) (p<0.001)). Use of NIV as the initial mode of respiratory support also increased (CPAP, 21.5%-28.0%; HFNC, 1%-7% (p<0.001)).HFNC was used earlier, and for longer, in those who received CPAP or mechanical ventilation. HFNC use was associated with decreased odds of death before discharge (adjusted OR (aOR) 0.19, 95% CI 0.17 to 0.22). Infants receiving CPAP but no HFNC died at an earlier median chronological age: CPAP group, 22 (IQR 10-39) days; HFNC group 40 (20-76) days (p<0.001). Among survivors, HFNC use was associated with increased odds of bronchopulmonary dysplasia (BPD) (aOR 2.98, 95% CI 2.81 to 3.15) and other adverse outcomes.

CONCLUSIONS

NIV use is increasing, particularly as initial respiratory support. HFNC use has increased significantly with a sevenfold increase soon after birth which was associated with higher rates of BPD. As more infants survive with BPD, we need robust clinical evidence, to improve outcomes with the use of NIV as initial and ongoing respiratory support.

dSPRINT: predicting DNA, RNA, ion, peptide and small molecule interaction sites within protein domains

Domains are instrumental in facilitating protein interactions with DNA, RNA, small molecules, ions and peptides. Identifying ligand-binding domains within sequences is a critical step in protein function annotation, and the ligand-binding properties of proteins are frequently analyzed based upon whether they contain one of these domains. To date, however, knowledge of whether and how protein domains interact with ligands has been limited to domains that have been observed in co-crystal structures; this leaves approximately two-thirds of human protein domain families uncharacterized with respect to whether and how they bind DNA, RNA, small molecules, ions and peptides. To fill this gap, we introduce dSPRINT, a novel ensemble machine learning method for predicting whether a domain binds DNA, RNA, small molecules, ions or peptides, along with the positions within it that participate in these types of interactions. In stringent cross-validation testing, we demonstrate that dSPRINT has an excellent performance in uncovering ligand-binding positions and domains. We also apply dSPRINT to newly characterize the molecular functions of domains of unknown function. dSPRINT's predictions can be transferred from domains to sequences, enabling predictions about the ligand-binding properties of 95% of human genes. The dSPRINT framework and its predictions for 6503 human protein domains are freely available at http://protdomain.princeton.edu/dsprint.

Chemical composition and biological effects of kratom (Mitragyna speciosa): In vitro studies with implications for efficacy and drug interactions

The safety and efficacy of kratom (Mitragyna speciosa) for treatment of pain is highly controversial. Kratom produces more than 40 structurally related alkaloids, but most studies have focused on just two of these, mitragynine and 7-hydroxymitragynine. Here, we profiled 53 commercial kratom products using untargeted LC-MS metabolomics, revealing two distinct chemotypes that contain different levels of the alkaloid speciofoline. Both chemotypes were confirmed with DNA barcoding to be M. speciosa. To evaluate the biological relevance of variable speciofoline levels in kratom, we compared the opioid receptor binding activity of speciofoline, mitragynine, and 7-hydroxymitragynine. Mitragynine and 7-hydroxymitragynine function as partial agonists of the human µ-opioid receptor, while speciofoline does not exhibit measurable binding affinity at the µ-, δ- or ƙ-opioid receptors. Importantly, mitragynine and 7-hydroxymitragynine demonstrate functional selectivity for G-protein signaling, with no measurable recruitment of β-arrestin. Overall, the study demonstrates the unique binding and functional profiles of the kratom alkaloids, suggesting potential utility for managing pain, but further studies are needed to follow up on these in vitro findings. All three kratom alkaloids tested inhibited select cytochrome P450 enzymes, suggesting a potential risk for adverse interactions when kratom is co-consumed with drugs metabolized by these enzymes.

Increased surfactant protein-D levels in the airways of preterm neonates with sepsis indicated responses to infectious challenges

AIM

Sepsis is multifactorial and potentially devastating for preterm neonates. Changes in surfactant protein-D (SP-D), phosphatidylcholine (PC) and PC molecular species during infection may indicate innate immunity or inflammation during sepsis. We aimed to compare these important pulmonary molecules in ventilated neonates without or with sepsis.

METHODS

Endotracheal aspirates were collected from preterm neonates born at 23-35 weeks and admitted to the neonatal intensive care unit at the John Radcliffe Hospital, Oxford, UK, from October 2000 to March 2002. Samples were collected at one day to 30 days and analysed for SP-D, total PC and PC molecular species concentrations using enzyme-linked immunosorbent assay and mass spectrometry.

RESULTS

We found that 8/54 (14.8%) neonates developed sepsis. SP-D (p < 0.0001), mono- and di-unsaturated PC were significantly increased (p = 0.05), and polyunsaturated PC was significantly decreased (p < 0.01) during sepsis compared to controls. SP-D:PC ratios were significantly increased during sepsis (p < 0.001), and SP-D concentrations were directly related to gestational age in neonates with sepsis (r²  = 0.389, p < 0.01).

CONCLUSION

Increased SP-D levels and changes in PC molecular species during sepsis were consistent with direct or indirect pulmonary inflammatory processes. Very preterm neonates we able to mount an acute inflammatory innate immune response to infectious challenges, despite low levels of surfactant proteins at birth.

Increased use of heated humidified high flow nasal cannula is associated with longer oxygen requirements

AIM

There has been an increased use of heated humidified high flow nasal canula (HFNC) in premature babies (PBs) admitted to our neonatal unit. The aim of this study is to identify clinical characteristics in PBs < 29 weeks gestational age (GA) that distinguish between those who did not or did receive HFNC.

METHODS

This study compared prospectively collected data from 2010 to 2012. Comparisons were undertaken between PBs<29 weeks GA who received continuous positive airway pressure (CPAP: 44/72 (61.1%)) to those who received both CPAP and HFNC (28/72 (38.9%)). Data were analysed using general linear models.

RESULTS

There were no significant differences in baseline characteristics between the groups (GA: 27.6 ± 1.1 vs. 27.5 ± 1.1 (weeks), birth weight: 1066 ± 209 vs. 1057 ± 304 (grams) respectively). When analysing outcome measures with multivariate analysis, we found the corrected GA to cease CPAP and oxygen were significantly longer in the HFNC group (31.2 ± 2.1 vs. 32.7 ± 2.0 weeks, P = 0.01 and 32.8 ± 3.5 vs. 36.5 ± 2.8 weeks, P < 0.0001 respectively).

CONCLUSIONS

Increased use of HFNC has been associated with increased oxygen requirements. These findings highlight the need to review the use of HFNC in small PBs.

Smoking in the family is most predictive of the development of childhood asthma in preterm babies <30 weeks gestation: Results of the Respiratory Outcomes Study 2 (RESPOS2)

OBJECTIVES

The Respiratory Outcomes Study 2 (RESPOS2) investigated the relationship between neonatal outcomes (specifically, chronic lung disease [CLD]) and environmental factors on the development of asthma and atopic outcomes at primary school age for preterm babies (PBs) <30 weeks gestational age (GA).

METHODS

The study included all surviving PBs <30 weeks GA admitted to the Neonatal Intensive Care Unit at Canberra Hospital, Australian Capital Territory between 2007 and 2009. Parents were sent a questionnaire regarding asthma and atopy symptoms when the PBs were aged 5-7 years old. Data were compared based on CLD status.

RESULTS

There were 103 PBs included in the study with a 68.9% response rate to the respiratory questionnaire (71/103). Of these PBs, 15/71 (21.1%) received a diagnosis of CLD. There were no significant differences with regards to asthma, hay fever or eczema in PBs either with or without CLD. The most significant predictor for the development of asthma was smoking in the family (Odds Ratio [OR]: 11.66, 95% Confidence Interval [CI]: 2.01-67.56) with a trend toward significance for family history of asthma (OR: 3.83, 95% CI: 0.85-17.25).

CONCLUSION

The RESPOS2 has confirmed previous reports that CLD in PBs <30 weeks GA is not associated with the development of childhood asthma, hay fever or eczema. In our group of PBs, the strongest predictor of the development of asthma was smoking in the family.

Heat and moisture exchangers versus heated humidifiers for mechanically ventilated adults and children

BACKGROUND

Invasive ventilation is used to assist or replace breathing when a person is unable to breathe adequately on their own. Because the upper airway is bypassed during mechanical ventilation, the respiratory system is no longer able to warm and moisten inhaled gases, potentially causing additional breathing problems in people who already require assisted breathing. To prevent these problems, gases are artificially warmed and humidified. There are two main forms of humidification, heat and moisture exchangers (HME) or heated humidifiers (HH). Both are associated with potential benefits and advantages but it is unclear whether HME or HH are more effective in preventing some of the negative outcomes associated with mechanical ventilation. This review was originally published in 2010 and updated in 2017.

OBJECTIVES

To assess whether heat and moisture exchangers or heated humidifiers are more effective in preventing complications in people receiving invasive mechanical ventilation and to identify whether the age group of participants, length of humidification, type of HME, and ventilation delivered through a tracheostomy had an effect on these findings.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, Embase and CINAHL up to May 2017 to identify randomized controlled trials (RCTs) and reference lists of included studies and relevant reviews. There were no language limitations.

SELECTION CRITERIA

We included RCTs comparing HMEs to HHs in adults and children receiving invasive ventilation. We included randomized cross-over studies.

DATA COLLECTION AND ANALYSIS

We assessed the quality of each study and extracted the relevant data. Where possible, we analysed data through meta-analysis. For dichotomous outcomes, we calculated the risk ratio (RR) and 95% confidence interval (95% CI). For continuous outcomes, we calculated the mean difference (MD) and 95% CI or standardized mean difference (SMD) and 95% CI for parallel studies. For cross-over trials, we calculated the MD and 95% CI using correlation estimates to correct for paired analyses. We aimed to conduct subgroup analyses based on the age group of participants, how long they received humidification, type of HME and whether ventilation was delivered through a tracheostomy. We also conducted sensitivity analysis to identify whether the quality of trials had an effect on meta-analytic findings.

MAIN RESULTS

We included 34 trials with 2848 participants; 26 studies were parallel-group design (2725 participants) and eight used a cross-over design (123 participants). Only three included studies reported data for infants or children. Two further studies (76 participants) are awaiting classification.There was no overall statistical difference in artificial airway occlusion (RR 1.59, 95% CI 0.60 to 4.19; participants = 2171; studies = 15; I2 = 54%), mortality (RR 1.03, 95% CI 0.89 to 1.20; participants = 1951; studies = 12; I2 = 0%) or pneumonia (RR 0.93, 95% CI 0.73 to 1.19; participants = 2251; studies = 13; I2 = 27%). There was some evidence that hydrophobic HMEs may reduce the risk of pneumonia compared to HHs (RR 0.48, 95% CI 0.28 to 0.82; participants = 469; studies = 3; I2 = 0%)..The overall GRADE quality of evidence was low. Although the overall methodological risk of bias was generally unclear for selection and detection bias and low risk for follow-up, the selection of study participants who were considered suitable for HME and in some studies removing participants from the HME group made the findings of this review difficult to generalize.

AUTHORS' CONCLUSIONS

The available evidence suggests no difference between HMEs and HHs on the primary outcomes of airway blockages, pneumonia and mortality. However, the overall low quality of this evidence makes it difficult to be confident about these findings. Further research is needed to compare HMEs to HHs, particularly in paediatric and neonatal populations, but research is also needed to more effectively compare different types of HME to each other as well as different types of HH.

Frenotomy for tongue-tie in newborn infants

BACKGROUND

Tongue-tie, or ankyloglossia, is a condition whereby the lingual frenulum attaches near the tip of the tongue and may be short, tight and thick. Tongue-tie is present in 4% to 11% of newborns. Tongue-tie has been cited as a cause of poor breastfeeding and maternal nipple pain. Frenotomy, which is commonly performed, may correct the restriction to tongue movement and allow more effective breastfeeding with less maternal nipple pain.

OBJECTIVES

To determine whether frenotomy is safe and effective in improving ability to feed orally among infants younger than three months of age with tongue-tie (and problems feeding).Also, to perform subgroup analysis to determine the following.• Severity of tongue-tie before frenotomy as measured by a validated tool (e.g. Hazelbaker Assessment Tool for Lingual Frenulum Function (ATLFF) scores < 11; scores ≥ 11) (Hazelbaker 1993).• Gestational age at birth (< 37 weeks' gestation; 37 weeks' gestation and above).• Method of feeding (breast or bottle).• Age at frenotomy (≤ 10 days of age; > 10 days to three months of age).• Severity of feeding difficulty (infants with feeding difficulty affecting weight gain (as assessed by infant's not regaining birth weight by day 14 or falling off centiles); infants with symptomatic feeding difficulty but thriving (greater than birth weight by day 14 and tracking centiles).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase and CINAHL up to January 2017, as well as previous reviews including cross-references, expert informants and journal handsearching. We searched clinical trials databases for ongoing and recently completed trials. We applied no language restrictions.

SELECTION CRITERIA

Randomised, quasi-randomised controlled trials or cluster-randomised trials that compared frenotomy versus no frenotomy or frenotomy versus sham procedure in newborn infants.

DATA COLLECTION AND ANALYSIS

Review authors extracted from the reports of clinical trials data regarding clinical outcomes including infant feeding, maternal nipple pain, duration of breastfeeding, cessation of breastfeeding, infant pain, excessive bleeding, infection at the site of frenotomy, ulceration at the site of frenotomy, damage to the tongue and/or submandibular ducts and recurrence of tongue-tie. We used the GRADE approach to assess the quality of evidence.

MAIN RESULTS

Five randomised trials met our inclusion criteria (n = 302). Three studies objectively measured infant breastfeeding using standardised assessment tools. Pooled analysis of two studies (n = 155) showed no change on a 10-point feeding scale following frenotomy (mean difference (MD) -0.1, 95% confidence interval (CI) -0.6 to 0.5 units on a 10-point feeding scale). A third study (n = 58) showed objective improvement on a 12-point feeding scale (MD 3.5, 95% CI 3.1 to 4.0 units of a 12-point feeding scale). Four studies objectively assessed maternal pain. Pooled analysis of three studies (n = 212) based on a 10-point pain scale showed a reduction in maternal pain scores following frenotomy (MD -0.7, 95% CI -1.4 to -0.1 units on a 10-point pain scale). A fourth study (n = 58) also showed a reduction in pain scores on a 50-point pain scale (MD -8.6, 95% CI -9.4 to -7.8 units on a 50-point pain scale). All studies reported no adverse effects following frenotomy. These studies had serious methodological shortcomings. They included small sample sizes, and only two studies blinded both mothers and assessors; one did not attempt blinding for mothers nor for assessors. All studies offered frenotomy to controls, and most controls underwent the procedure, suggesting lack of equipoise. No study was able to report whether frenotomy led to long-term successful breastfeeding.

AUTHORS' CONCLUSIONS

Frenotomy reduced breastfeeding mothers' nipple pain in the short term. Investigators did not find a consistent positive effect on infant breastfeeding. Researchers reported no serious complications, but the total number of infants studied was small. The small number of trials along with methodological shortcomings limits the certainty of these findings. Further randomised controlled trials of high methodological quality are necessary to determine the effects of frenotomy.

Tongue-tie in the newborn: Follow-up in the first 6 months

BACKGROUND

Over the last decade, a number of studies have demonstrated that early division of tongue-tie (TT) is associated with significant feeding benefits to both mother and baby. Notwithstanding, it remains a controversial procedure. We examined the breastfeeding outcomes of a cohort of babies at 1-2 weeks (follow-up 1) and 3-5 months (follow-up 2), post-TT division.

METHODS

We undertook a cohort study on all mother/baby dyads who had a TT divided at Canberra Hospital between 1 July 2013 and 30 June 2014. We contacted the mothers of both follow-up groups by telephone, focusing on breastfeeding and maternal pain.

RESULTS

Follow-up 1 consisted of 116/182 (63.7%) of mothers in the study; contacted at 12.4+-7.8 days post-division. Of these, 107/116 (92.2%) were still breastfeeding, with 11/15 (73.3%) of the mothers who had ceased breastfeeding before division having re-established it at the time of follow-up (p < 0.00l). Additionally, 90/101 (89.1%) valid responses reported decreased nipple pain following TT division. Follow-up 2 consisted of 112/182 (61.5%) of all mothers in the study; contacted at 3.7+-1.8 months of age. Of these, 86/112 (76.8%) were still breastfeeding, with 11/15 (73.3%) of mothers who had ceased breastfeeding before division having re-established it at follow-up (p < 0.001).

CONCLUSION

A divided TT was associated with benefits at both periods of follow-up. There was (i) an increase in overall breastfeeding rates and (ii) a decrease in maternal pain.

CeasIng Cpap At standarD criteriA (CICADA): Implementation improves neonatal outcomes

BACKGROUND

A previous randomised controlled trial (RCT) in babies born < 30 weeks gestation found the so-called CICADA method (ceasing continuous positive airways pressure (CPAP) with a view to remain off rather than slow weaning) significantly reduced CPAP time. Post-RCT we introduced the CICADA method and evaluated whether the improved outcomes of the CICADA method during the RCT were replicated in clinical practice.

AIM

The aim of the study is to compare cardio-respiratory outcomes in PBs < 30 weeks GA over three epochs: (i) pre RCT, (ii) during RCT and (iii) post RCT implementation.

METHODS

The study used prospective data to compare baseline characteristics and cardio-respiratory outcomes over the three epochs.

RESULTS

There were 270/393(69%) PBs < 30 weeks GA who fulfilled the inclusion criteria over the three epochs. No significant differences were found in GA or birthweight between the three epochs (27.9 ± 1.3, 27.7 ± 1.4, 28.0 ± 1.3 (weeks ± 1 standard deviation); and 1100 ± 252, 1086 ± 251, 1094 ± 320 (grams ± 1 standard deviation)). There were significant decreases in CPAP days and corrected GA to cease CPAP post implementation (20.5 ± 2.1, 21.1 ± 2.1, 16.5 ± 1.8 (days ± SE); P = 0.006 and 33.3 ± 0.4, 33.5 ± 0.4, 32.6 ± 0.4 (weeks ± SE); P = 0.01). Compared with the pre RCT epoch, there were significant reductions in patent ductus arteriosus (36/78 (46%), 33/87 (37%), 18/103 (17%); P < 0.001) and chronic lung disease (40/78 (51%), 19/87 (21%), 30/103 (29%); P < 0.001).

CONCLUSIONS

CPAP time, corrected GA to cease CPAP, patent ductus arteriosus and chronic lung disease significantly reduced following the introduction of the CICADA method. Early cessation of CPAP expedites the transition from neonatal intensive care to special care.

Sight-Threatening Retinopathy of Prematurity: Changing Trends in Treatment

PURPOSE

To study the incidence and treatment of severe retinopathy of prematurity (ROP) in infants younger than 30 weeks' gestational age (GA) in New South Wales and the Australian Capital Territory, Australia, from 2003 to 2008. These data were then compared to data from previously reported epochs (1986 to 1987, 1992 to 1997, and 1998 to 2002).

METHODS

Data were divided into two sub-epochs (2003 to 2005 and 2006 to 2008) to study trends and combined to compare over 22 years.

RESULTS

From 2003 to 2008, 2,550 of 3,004 (84.9%) infants survived, 200 (7.8%) were diagnosed as having severe ROP, and 119 (59.5%) required laser therapy. No significant difference in the incidence of severe ROP or treatment rate in infants younger than 27 and 30 weeks' GA from 2003 to 2005 and 2006 to 2008 occurred. Similarly, between 1986 and 2008 there was no difference in the incidence of severe ROP. However, the treatment rate significantly increased during this time.

CONCLUSIONS

The incidence of severe ROP has been stable since 1986. However, laser treatment significantly increased to include 8 infants with stage 2 ROP from 2003 to 2008.

Tongue-tie in the newborn: early diagnosis and division prevents poor breastfeeding outcomes

BACKGROUND

In 2011, the Centenary Hospital Neonatal Department guidelines were modified and recommended delaying the division of infant tongue-tie (TT) until after 7 days of life. This paper looks at the effect of these guidelines in practice by comparing patient characteristics and breastfeeding practices before and after the change.

METHODS

We used prospective data from mothers and babies who had TT division to compare breastfeeding practices in 2008 and 2011. Data included: gestational age (GA), birth-weight (BWt), gender, age at TT division, degrees of TT and maternal feeding pre/post TT division.

RESULTS

There were no significant differences between the 2 years in the rate of TT division, 115/2471 (4.7%) vs 144/2891 (5.0%) (TT divided/birth number) or GA 39.6 ± 1.2 vs 39.5 ± 1.2 (weeks); BWt 3.48 ± 0.45 vs 3.52 ± 0.50 (kg); and Male:Female 77:38 (2.0:1.0) vs 91:53 (1.7:1.0). There was, however, an increase in the age the TT was divided 6.5 ± 4.5 vs 9.7 ± 6.2 (days) p < 0.0001; and an increased number of mothers unable to continue breastfeeding and providing expressed breastmilk: 4/115 (3.5%) vs 25/144 (17.4%) p = 0.0004 (expressing/divided). A majority (> 90%) of mothers noted an immediate improvement in feeding and decreased nipple pain. No significant complications occurred.

CONCLUSION

The rate of TT division did not change after the implementation of new guidelines post 2011. However, there has been a significant increase in the age at TT division and the number of mothers unable to breastfeed, primarily due to nipple pain and poor attachment. If feeding is problematic, the TT should be divided as early as possible to reduce breastfeeding cessation and improve breastfeeding satisfaction.

CeasIng Cpap At standarD criteriA (CICADA): impact on weight gain, time to full feeds and caffeine use

INTRODUCTION

In our previous randomised controlled trial (RCT), we have shown in preterm babies (PBs) <30 weeks gestation that CeasIng Cpap At standarD criteriA (CICADA (method 1)) compared with cycling off continuous positive airway pressure (CPAP) gradually (method 2) or cycling off CPAP gradually with low flow air/oxygen during periods off CPAP (method 3) reduces CPAP cessation time in PBs <30 weeks gestation.

METHOD

This retrospective study reviewed weight gain, time to reach full feeds and time to cease caffeine in PBs previously enrolled in the RCT.

RESULTS

Data were collected from 162 of the 177 PBs, and there was no significant difference in the projected weight gain between the three methods. Based on intention to treat, the time taken to reach full feeds for all three methods showed no significant difference. However, post hoc analysis showed the CICADA method compared with cycling off gradually just failed significance (30.3±1.6 vs 31.1±2.4 (weeks corrected gestational age (Wks CGA±SD)), p=0.077). Analysis of time to cease caffeine showed there was a significant difference between the methods with PBs randomised to the CICADA method compared with the cycling off method ceasing caffeine almost a week earlier (33.6±2.4 vs 34.5±2.8 (Wks CGA±SD), p=0.02).

CONCLUSIONS

This retrospective study provides evidence to substantiate the optimum method of ceasing CPAP; the CICADA method, does not adversely affect weight gain, time to reach full feeds and may reduce time to cease caffeine in PBs <30 weeks gestation.

Respiratory outcomes study (RESPOS) for preterm infants at primary school age

OBJECTIVE

Pulmonary function abnormalities and hospital re-admissions in survivors of neonatal lung disease remain highly prevalent. The respiratory outcomes study (RESPOS) aimed to investigate the respiratory and associated atopy outcomes in preterm infants <30 weeks gestational age (GA) and/or birth-weight (BWt) <1000 g at primary school age, and to compare these outcomes between infants with and without chronic lung disease (CLD).

METHODS

In the RESPOS 92 parents of preterm infants admitted to the Neonatal unit in Canberra Hospital between 1/1/2001 and 31/12/2003 were sent a questionnaire regarding their respiratory, atopy management and follow-up.

RESULTS

Fifty-three parents responded, including 28 preterm infants who had CLD and 25 who had no CLD. The gestational age was significantly lower in the CLD group compared to the non-CLD group [26.9 (26.3-27.5) CLD and 28.6 (28.3-29.0) non-CLD] [weeks [95% confidence interval (CI)]], as was the birth weight [973 (877.4-1068.8) CLD versus 1221 (1135.0-1307.0) non-CLD] [g (CI)]. CLD infants compared to non-CLD infants were significantly more likely to have been: given surfactant, ventilated and on oxygen at 28 days and 36 weeks. These neonates were also more likely to have: been discharged from the neonatal unit on oxygen, exhibit a history of PDA or sepsis and to have a current paediatrician. However, despite these differences, there was no significant difference in the proportion of asthma or atopic disease between the two groups.

CONCLUSIONS

The RESPOS could not demonstrate respiratory and/or atopy differences between the CLD and the non-CLD groups at primary school age.

Tongue-tie in the newborn: what, when, who and how? Exploring tongue-tie division

The division of tongue-tie (TT) in babies with feeding problems has become a more accepted procedure in recent years (Bowley & Arul 2013). Although case series reports had described the benefits of division in problematic breastfeeding (Ballard, Auer & Khoury et al 2002; Notestine 1990), it was not until randomised controlled trials (RCTs) provided significant evidence of improvement that the procedure became more accepted (Berry, Griffiths & Westcott 2012; Buryk, Bloom & Shope 2011; Dollberg et al 2006; Emond et al 2014; Hogan, Westcott & Griffiths 2005). However there are still several areas of debate. These include: 1) what type of TT produces problems with feeding and thus what type of TT should be divided, 2) who should have the procedure, 3) when should the TT division be performed and 4) how should the TT be divided. In this review I will discuss these areas of debate and shed some light on this very common but often devastating congenital condition.

Inspired gas humidity and temperature during mechanical ventilation with the Stephanie ventilator

AIMS

To measure inspired gas humidity and temperature delivered by a Stephanie neonatal ventilator with variations in (i) circuit length; (ii) circuit insulation; (iii) proximal airway temperature probe (pATP) position; (iv) inspiratory temperature (offset); and (v) incubator temperatures.

METHODS

Using the Stephanie neonatal ventilator, inspired gas humidity and temperature were measured during mechanical ventilation at the distal inspiratory limb and 3 cm down the endotracheal tube. Measurements were made with a long or short circuit; with or without insulation of the inspiratory limb; proximal ATP (pATP) either within or external to the incubator; at two different inspiratory temperature (offset) of 37(-0.5) and 39(-2.0)°C; and at three different incubator temperatures of 32, 34.5, and 37°C.

RESULTS

Long circuits produced significantly higher inspired humidity than short circuits at all incubator settings, while only at 32°C was the inspired temperature higher. In the long circuits, insulation further improved the inspired humidity especially at 39(-2.0)°C, while only at incubator temperatures of 32 and 37°C did insulation significantly improve inspired temperature. Positioning the pATP outside the incubator did not result in higher inspired humidity but did significantly improve inspired temperature. An inspiratory temperature (offset) of 39(-2.0)°C delivered significantly higher inspired humidity and temperature than the 37(-0.5)°C especially when insulated.

CONCLUSIONS

Long insulated Stephanie circuits should be used for neonatal ventilation when the infant is nursed in an incubator. The recommended inspiratory temperature (offset) of 37(-0.5)°C produced inspired humidity and temperature below international standards, and we suggest an increase to 39(-2.0)°C.

Methods of weaning preterm babies <30 weeks gestation off CPAP: a multicentre randomised controlled trial

BACKGROUND

Controversy exists whether different continuous positive airway pressure (CPAP) weaning methods influence time to wean off CPAP, CPAP duration, oxygen duration, Bronchopulmonary Dysplasia (BPD) or length of admission.

AIMS

In a multicentre randomised controlled trial, the authors have primarily compared CPAP weaning methods impact on time to wean off CPAP and CPAP duration and secondarily their effect on oxygen duration, BPD and time of admission.

METHODS

Between April 2006 and October 2009, 177 infants <30 weeks gestational age (GA) who fulfilled stability criteria on CPAP were randomised to one of the three CPAP weaning methods (M). M1: Taken 'OFF' CPAP with the view to stay 'OFF'. M2: Cycled on and off CPAP with incremental time 'OFF'. M3: As with m(2), cycled on and off CPAP but during 'OFF' periods were supported by 2 mm nasal cannula at a flow of 0.5 l/min.

RESULTS

Based on intention to treat analysis, there was no significant difference in mean GA or birthweight between the groups (27.1 ± 1.4, 26.9 ± 1.6 and 27.3 ± 1.5 (weeks ± 1SD) and 988 ± 247, 987 ± 249 and 1015 ± 257 (grams ± 1SD), respectively). Primary outcomes showed M1 produced a significantly shorter time to wean from CPAP (11.3 ± 0.8, 16.8 ± 1.0, 19.4 ± 1.3 (days ± 1SE) p<0.0001, respectively) and CPAP duration (24.4 ± 0.1, 38.6 ± 0.1, 30.5 ± 0.1 (days ± 1SE) p<0.0001, respectively). All the secondary outcomes were significantly shorter with M1, (oxygen duration: 24.1 ± 1.5, 45.8 ± 2.2, 34.1 ± 2.0 (days ± 1SE) p<0.0001, BPD: 7/56 (12.5%), 29/69 (42%), 10/52 (19%) p=0.011 and length of admission: 58.5 ± 0.1, 73.8 ± 0.1 69.5 ± 0.1 (days ± 1SE) p<0.0001, respectively).

CONCLUSION

Method 1 significantly shortens CPAP weaning time, CPAP duration, oxygen duration, BPD and admission time.

Heated humidification versus heat and moisture exchangers for ventilated adults and children

BACKGROUND

Humidification by artificial means must be provided when the upper airway is bypassed during mechanical ventilation. Heated humidification (HH) and heat and moisture exchangers (HME) are the most commonly used types of artificial humidification in this situation.

OBJECTIVES

To determine whether HHs or HMEs are more effective in preventing mortality and other complications in people who are mechanically ventilated.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library 2010, Issue 4) and MEDLINE, EMBASE and CINAHL (January, 2010) to identify relevant randomized controlled trials (RCTs).

SELECTION CRITERIA

We included RCTs comparing heat and moisture exchangers (HMEs) to heated humidifiers (HHs) in mechanically ventilated adults and children. We included randomized crossover studies.

DATA COLLECTION AND ANALYSIS

We assessed the quality of each study and extracted the relevant data. Where appropriate, results from relevant studies were meta-analysed for individual outcomes.

MAIN RESULTS

We included 33 trials with 2833 participants, 25 studies were parallel group design (n = 2710) and eight crossover design (n = 123). Only three included studies reported data for infants or children. There was no overall effect on artificial airway occlusion, mortality, pneumonia, or respiratory complications; however, the PaCO(2) and minute ventilation were increased when HMEs were compared to HHs and body temperature was lower. The cost of HMEs was lower in all studies that reported this outcome. There was some evidence that hydrophobic HMEs may reduce the risk of pneumonia and that blockages of artificial airways may be increased with the use of HMEs in certain subgroups of patients.

AUTHORS' CONCLUSIONS

There is little evidence of an overall difference between HMEs and HHs. However, hydrophobic HMEs may reduce the risk of pneumonia and the use of an HME may increase artificial airway occlusion in certain subgroups of patients. Therefore, HMEs may not be suitable for patients with limited respiratory reserve or prone to airway blockage. Further research is needed relating to hydrophobic versus hygroscopic HMEs and the use of HMEs in the paediatric and neonatal populations. As the design of HMEs evolves, evaluation of new generation HMEs will also need to be undertaken.

Severe retinopathy of prematurity in infants <30 weeks' gestation in New South Wales and the Australian Capital Territory from 1992 to 2002

BACKGROUND

Retinopathy of prematurity (ROP) significantly increased in New South Wales (NSW) from 1986 to 1994, but more recent data suggest that there has now been a decrease.

OBJECTIVE

To study the incidence and treatment of severe ROP (stage >or=3) in NSW and the Australian Capital Territory (ACT) from 1992 to 2002.

METHODS

Data collected prospectively from the Neonatal Intensive Care Units' (NICUS) Data Collection over an 11-year period in infants <30 weeks' gestation were divided into four epochs and analysed retrospectively. The incidence and treatment of severe ROP were compared for gestational ages <or=24 weeks', 25-26 weeks' and 27-29 weeks' gestation over the four epochs.

RESULTS

In infants <or=24 weeks' gestation the incidence of severe ROP and those treated increased significantly (stage >or=3: from 17 (41.5%) to 41 (53.9%), p=0.052; treated: from 8 (19.5%) to 25 (32.9%), p<0.05 (first and fourth epoch)). In infants 25-26 weeks' gestation the incidence of severe ROP decreased significantly whereas there was a non-significant increase in those treated (stage >or=3: from 55 (26.2%) to 46 (19.3%), p<0.05; treated: from 19 (9.0%) to 32 (13.4%)). In infants 27-29 weeks' gestation, there was no significant change in the incidence of severe ROP or those treated (stage >or=3: from 30 (4.1%) to 17 (2.4%); treated: from 14 (1.9%) to 8 (1.1%)).

CONCLUSION

In infants <or=24 weeks' gestation there has been a significant increase in severe ROP, and in infants <27 weeks' gestation the numbers treated for severe ROP increased.

Eye-hand co-ordination skills in very preterm infants <29 weeks gestation at 3 years: Effects of preterm birth and retinopathy of prematurity

INTRODUCTION

Preterm infants are known to have low gross motor and fine motor skills. We questioned whether poor eye-hand coordination skills are associated with moderate to severe stages of Retinopathy of Prematurity (ROP).

AIMS

The aim of this study was to examine development, with specific reference to eye-hand coordination skills, among preterm infants <29 weeks gestation with different stages of ROP at 3 years of age.

METHODS AND MATERIALS

Fifteen preterm infants (<29 weeks gestation) who developed Stage 3 ROP were matched for gestation, birthweight and gender with infants who developed Stage 2 and Stage 1/no ROP. Developmental (Griffiths Mental Development Scales and Peabody Developmental Motor Scales) and ophthalmic assessments in the 3 matched groups of 15 were performed at 3 years of age.

RESULTS

1) Whilst the eye-hand coordination scores and Peabody fine motor scores were lower in the Stage 3 ROP group, they were not significantly lower than the other ROP groups. 2) Locomotor, Peabody gross motor skills and hearing and speech were significantly lower in the infants with Stage 3 ROP. The other developmental domains were not significantly different to the severe ROP group. 3) All 3 groups (of preterm infants) had lower eye-hand coordination and Peabody fine motor scores compared to test norms. 4) There were 8 of 15 infants with Stage 3 ROP who developed moderate visual problems by 3 years of age.

CONCLUSION

In preterm infants, low eye-hand coordination/fine motor scores are likely to be due to their extreme prematurity.

Inspired gas humidity during mechanical ventilation: effects of humidification chamber, airway temperature probe position and environmental conditions

OBJECTIVES

To determine the inspired gas humidity during mechanical ventilation with: (i) four different humidification chambers; (ii) two airway temperature probe (ATP) positions; (iii) five different humidicrib temperatures; and (iv) insulating the inspiratory limb with bubble wrap.

METHODOLOGY

An observational study in the Neonatal Laboratory and Neonatal Intensive Care Unit, Westmead Hospital. The humidity of the inspired gas was measured at the proximal end of the endotracheal tube (ETT) during mechanical ventilation. Inspired humidity measurements were made with four different humidification chambers (Fisher & Paykel (F&P Healthcare Pty Ltd, Auckland, New Zealand) auto refill MR290. F&P manual refill MR310, Suruga (Suruga Inc. Humidifiers, Vincent Medical, Dongguan, China) manual refill MI-20 and MI-10F) with the humidity control (relative humidity setting) set at - 2. Measurements were made with the ATP positioned either; (A) at the distal end of the inspiratory tube inside the humidicrib or (B) outside the humidicrib 50 cm proximal to the ETT. The inspired gas temperatures were set at 36.5 degrees C and at 39.0 degrees C, respectively. For each of the different humidification chambers and ATP positions, inspired humidity measurements were made with the humidicrib temperature set at 30.8, 32.9, 35.2, 36.2, or 37.2 degrees C. Two further sets of measurements were made, one with the inspiratory limb insulated with bubble wrap and the second set without bubble wrap.

RESULTS

There were significant differences in inspired humidity with the four humidification chambers at both ATP positions at all humidicrib temperatures. Both Suruga humidification chambers produced significantly higher inspired gas humidities under most conditions. Positioning the ATP outside the humidicrib produced significantly higher inspired gas humidities than with the ATP inside the humidicrib. Insulating the inspiratory tubing with bubble wrap also significantly improved the inspired gas humidity.

CONCLUSIONS

Significant differences in inspired gas humidity were found with the humidification chambers tested. The position of the ATP and the set temperature had a significant impact on the absolute humidity of the inspired gas. In general, higher inspired gas humidities were obtained with the ATP outside the humidicrib. However, condensation of water close to the ETT appeared at low humidicrib temperatures (< 36.2 degrees C) with the ATP outside the humidicrib and extreme care should be taken that particulate water does not enter the lungs under these conditions.

Inspired gas temperature during mechanical ventilation: effects of environmental temperature and airway temperature probe position

OBJECTIVES

To determine the inspired gas temperature during mechanical ventilation with: (i) five different humidicrib temperatures; (ii) two airway temperature probe (ATP) positions; and (iii) four ATP adaptors.

METHODOLOGY

An observational study in the Neonatal Intensive Care Laboratory, Westmead Hospital. The inspired gas temperature was measured at the proximal end of the endotracheal tube (ETT) during conventional mechanical ventilation using a Tele-thermometer. Inspired gas temperature measurements were made with: (i) the humidicrib temperature set at 30.8. 32.9, 35.2, 36.2. or 37.2 degrees C; (ii) the ATP either (A) positioned inside the humidicrib at the distal end of the inspiratory tubing or (B) positioned outside the humidicrib 50 cm proximal to the ETT, with the inspired gas temperatures set at 36.5 and 39.0 degrees C, respectively; and (iii) the measurements repeated with four different ATP adaptors at each humidicrib temperature and each ATP position.

RESULTS

With the ATP inside the humidicrib, there were no significant differences between set and actual inspired gas temperature. However, with the ATP outside the humidicrib, there were significant decreases in inspired gas temperature at each humidicrib temperature. For instance, with the ATP outside the humidicrib and set at 39.0 degrees C, the inspired gas temperature decreased to 34.7+/-0.2 degrees C at a humidicrib temperature of 30.8 degrees C and to 37.7+/-0.2 degrees C at a humidicrib temperature of 37.2 degrees C. The type of ATP adaptor also had a significant effect on inspired gas temperature.

CONCLUSIONS

With the ATP placed outside the humidicrib and with variations of humidicrib temperature, infants are likely to have inspired gas temperatures that are significantly different to the desired temperature. Certain ATP adaptors cause these variations in inspired gas temperature to be more pronounced. Extreme care must be used to avoid suboptimal inspired gas temperatures with these environmental variations and the ATP positioned outside the humidicrib.

Umbilical cord blood lactate in normal infants: comparison between two methods of measurement

OBJECTIVES

Firstly, to determine the accuracy of the Radiometer ABL 625 lactate electrode (Radiometer Medical Pty Ltd, Nunawading, Victoria, Australia) by comparing the lactate values obtained by this method to those obtained with the Hitachi 917 lactate analyser (Boehringer Mannheim Corporation, Charlottetown, Prince Edward Island, Canada). Secondly, to determine the effect of delay in measurement on blood lactate levels.

METHODOLOGY

Umbilical venous (UCV) blood samples were obtained from healthy term infants delivered vaginally. Lactate levels were measured with the Radiometer ABL 625 lactate electrode in the Neonatal Intensive Care Unit, Westmead Hospital and with the Hitachi 917 lactate analyser in 49 paired samples. In addition 26 UCV blood samples were placed in ice slurry and a further 26 samples at room temperature and blood lactate was measured at 5-min intervals for 30 min to determine the change of lactate levels with time.

RESULTS

The lactate levels obtained from the Radiometer ABL 625 lactate electrode were consistently lower than the levels obtained from the Hitachi 917 lactate analyser (mean difference - 0.24), but the correlation was high (r = 0.97). The blood lactate levels increased at the rate of 0.012 mmol/L per min if the blood was left at room temperature. The lactate levels remained stable for 20 min if the blood was placed in ice slurry.

CONCLUSION

The Radiometer ABL 625 lactate electrode was easy to use and there was high correlation with the values obtained by the standard laboratory method. The blood specimen must be place in an ice slurry if a delay in analysis is anticipated.

Role of ureaplasma urealyticum in lung disease of prematurity

AIM

To examine the role of Ureaplasma urealyticum colonisation or infection in neonatal lung disease.

METHODS

Endotracheal aspirates from ventilated infants less than 28 weeks of gestation were cultured for U urealyticum and outcomes compared in infants with positive and negative cultures.

RESULTS

U urealyticum was isolated from aspirates of 39 of 143 (27%) infants. Respiratory distress syndrome (RDS) occurred significantly less often in colonised, than in non-colonised infants (p=0.002). Multivariate logistic regression analysis showed that in singleton infants, ureaplasma colonisation was the only independent (negative) predictor of RDS (OR 0.36; p=0. 02). Both gestational age (OR 0.46; p=0.006) and isolation of U urealyticum (OR 3.0; p=0.05) were independent predictors of chronic lung disease (CLD), as defined by requirement for supplemental oxygen at 36 weeks of gestational age. Multiple gestation was also a major independent predictor of RDS and CLD.

CONCLUSIONS

Colonisation or infection with ureaplasma apparently protects premature infants against the development of RDS (suggesting intrauterine infection). However, in singleton infants, it predisposes to development of CLD, independently of gestational age. Treatment of affected infants after birth is unlikely to significantly improve the outcome and methods are required to identify and treat the women with intrauterine ureaplasmal infection, before preterm delivery occurs.

Retinopathy of prematurity in infants < 32 weeks' gestation at birth in New South Wales in 1993 and 1994

OBJECTIVE

To study the incidence and severity of retinopathy of prematurity (ROP) in infants < 32 weeks' gestation.

DESIGN

Review of the records maintained in the New South Wales Neonatal Intensive Care Unit Study (NICUS) database on infants admitted to the neonatal intensive care units (NICU) in NSW from 1 January 1993 to 31 December 1994.

RESULTS

In the more premature infants, 23-26 weeks' gestation, 65% developed ROP (102 of 157 examined for ROP). Forty-four infants (28%) developed severe ROP (Stage ≥ 3 ROP), 19 infants (12.1%) required cryo/laser therapy and one infant (0.6%) in this group had a retinal detachment. One hundred and fifty-seven of 159 surviving infants (98.7%) were examined for ROP. In the infants 27-28 weeks' gestation, 38.3% developed ROP (103 of 269 examined for ROP). Fifteen infants (5.6%) developed severe ROP, seven infants (2.6%) required cryo/laser therapy for threshold ROP and three infants (1.1%) in this group had a retinal detachment. Two hundred and sixty-nine of 299 surviving infants (90%) were examined for ROP. In the infants 29-31 weeks' gestation, 10.8% developed ROP (48 of 443 examined for ROP). Six infants (1.4%) developed severe ROP, one infant (0.2%) required cryo/laser therapy for threshold ROP and no infant in this group had a retinal detachment. However, only 443 of 681 surviving infants (65.1%) in this group were examined for ROP. Of the four infants with detached retinas, one was a 25 week gestation infant weighing 840 g, two were 27 weeks' gestation weighing 960 and 980 g and one infant was a 28 week gestation infant weighing 620 g. No infant developed Stage 5 ROP.

CONCLUSION

In the more mature infants 29-31 weeks' gestation, the rate of ROP is low, although severe ROP still occurs. However, only 65.1% of these infants were examined for ROP and we should be diligent in screening for ROP in the sicker infants in this group. The incidence of severe ROP as well as the rate of cryo/laser therapy in premature infants 23-26 weeks' in NSW has not changed since the increases seen in the early 1990s. Retinal detachment also occurs in the infants 27-28 weeks' gestation and it is important that all these infants are screened for ROP.

Serial phospholipid analysis in preterm infants: comparison of Exosurf and Survanta

The initial clinical response to synthetic or natural surfactant is different and long-term complications from meta-analysis suggest that bronchopulmonary dysplasia and retinopathy of prematurity may be increased in infants given synthetic surfactant. It is possible that this is due to differences in the phospholipid composition of lung fluid following administration of these surfactants. Infants less than 32 weeks gestation with respiratory distress syndrome (RDS) were randomly assigned to receive either Exosurf, an artificial surfactant, or Survanta, a natural surfactant. Endotracheal or hypopharyngeal aspirates were obtained from these infants and from control infants who had normal lungs. The aspirates were taken prior to and up to 28 days following surfactant administration. The different phospholipids were separated by thin layer chromatography and expressed as a percent of total phospholipid measured. Infants with normal lungs had a higher proportion of phosphatidylcholine than those with RDS prior to treatment. The infants with normal lungs had a greater proportion of phosphatidylinositol in their lung aspirates than both treatment groups at 24 h. Infants in the Survanta group had a higher proportion of phosphatidylglycerol at 48 h than the group with normal lungs. No other differences were found in phospholipid composition up to 28 days. There were no major differences in the phospholipid profile in infants with RDS treated with either Exosurf or Survanta. In conclusion, neither the clinical differences initially seen between infants treated with either Exosurf or Survanta, nor the long-term outcome could be explained by the phospholipid composition of serial samples of lung aspirates.

Cytological changes in endotracheal aspirates associated with chronic lung disease

Endotracheal aspirates taken serially from mechanically ventilated premature infants born at < 28 weeks gestation between March 1992 and August 1993 were studied to determine whether early cytological changes would be a good predictor of lung damage in infants who develop chronic lung disease (CLD). CLD was diagnosed if the infant required supplemental oxygen at 36 weeks corrected gestational age. Fifty-five infants were enrolled in the study, five died and of the 50 infants remaining, 17 (34%) developed CLD. The infants with CLD had a significantly lower gestation (25.5 +/- 1.8 (mean +/- 1 SD) versus 26.2 +/- 0.9 weeks, p < 0.05), significantly more required surfactant (14/17 vs. 16/33, p < 0.05) and were ventilated for a significantly longer period (43.3 +/- 26.6 vs. 19.3 +/- 12.8 days, p < 0.0001). Endotracheal aspirate cytology showed that infants with CLD had significantly more degenerated columnar epithelial cells on day 3 (p = 0.001), and more neutrophils on day 10 (p = 0.007). Though not predictive of CLD, cytological changes consistent with bronchial epithelial and pulmonary damage followed by an inflammatory response were found in the tracheal aspirates of a group of infants clinically diagnosed with CLD.

Retinopathy of prematurity in infants <29 weeks' gestation at birth in New South Wales from 1986-92

OBJECTIVE

To study the effect of increased survival of infants <29 weeks' gestation on the incidence and severity of retinopathy of prematurity (ROP).

METHODOLOGY

Review of prospective records from 1986 to 1992 kept in the New South Wales (NSW) NICUS database on infants admitted to the neonatal intensive care units (NICU) in NSW. The survival rate and the incidence and severity of ROP on all infants <29 weeks' gestation admitted to the NICUs in NSW from 1 July 1986 to 31 December 1987 were compared to a similar group of infants admitted from 1 January 1992 to 31 December 1992.

RESULTS

There was a significant difference in the survival rate of infants admitted between the two periods (235 of 376, 62.5% survival vs 255 of 336, 75.9% survival, respectively, P<0.0001). The odds ratio for survival adjusted for gestational age in the second period was 1.76 [1.24, 2.48 (95% confidence interval), P<0.002]. There was a slight increase in ROP in the second period (79 of 172 examined, 45.9% ROP vs 133 of 238 examined, 55.8% ROP, respectively). There was a rise in the number of infants with Stage 3 ROP in the second time period (14 of 172 examined, 8.1% ROP vs 41 of 238 examined, 17.2% ROP, respectively). However, fewer infants had detached retinas or > or = Stage 4 ROP in the second group [7 of 172, (4.1 %) vs 3 of 238, (1.3%), respectively]. This may be a reflection of the increase in the use of cryo- or laser therapy for Stage 3 ROP with 'plus' disease [2 of 172 examined, (1.2%) vs 18 of 238 examined, (7.6%), respectively].

CONCLUSIONS

With the increase in survival of the very preterm infant in recent years, there has been an increase in severe ROP (> or = Stage 3) in NSW. Despite the increased survival of the highest at-risk group (24- to 26-week gestation infants), there have been fewer cases of retinal detachment. There was also a rise in the number of infants receiving cryo- or laser therapy intervention.

Chronic oxygen dependency in infants born at 24-32 weeks' gestation: the role of antenatal and neonatal factors

OBJECTIVES

To study the incidence of chronic oxygen dependency (COD) among ventilated survivors born at 24-32 weeks gestation from 1986 to 1994 and to identify antenatal and neonatal factors that may have changed with time; and to identify antenatal and neonatal factors that could contribute to the development of COD in infants born at 24-32 weeks gestation using a case control model.

METHODOLOGY

Infants born at 24-32 weeks gestation in one tertiary referral centre between 1986 and 1994 and admitted to the neonatal intensive care unit for respiratory support were studied. Data accumulated prospectively since 1986 in survivors of ventilation were analyzed to identify antenatal and neonatal factors that could have changed with time. The cohort of infants who developed COD were matched for gestation and time of birth with a control group of infants who did not have COD. Significant factors that could have contributed to the development of COD were identified using forward logistic regression analysis.

RESULTS

The number of mothers admitted for threatened premature labour (TPL), and pregnancy induced hypertension decreased with time while the use of antenatal steroids and maternal antibiotics increased. More infants were delivered by Caesarean section during the later years. There was an increase in neonatal septicaemia with time while there were decreases in hyaline membrane disease, pneumothorax, pulmonary interstitial emphysema, use of high peak inspiratory pressure (PIP) and high inspired oxygen. The incidence of COD decreased. The case controlled study revealed a significant positive association between COD and male gender, birthweight less than the 10th percentile for gestation, PIP over 30 cm H2O, septicaemia and significant patent ductus arteriosus (PDA) requiring indomethacin. There was a negative association with TPL.

CONCLUSIONS

Further decrease in COD can be achieved only if septicaemia, PDA and the use of high PIP can be avoided. The most effective way of reducing the incidence of COD is by reducing the incidence of prematurity.

Retinopathy of prematurity in infants less than 29 weeks' gestation: 3 1/2 years pre- and postsurfactant

OBJECTIVE

To determine the effects of surfactant on retinopathy of prematurity (ROP).

DESIGN

We compared infants for 3 1/2 years both before and after the introduction of surfactant in our neonatal intensive care unit (NICU) using prospectively collected data. Exogenous surfactant (Exosurf) was introduced into our NICU on July 1, 1991.

METHODS

We compared the incidence and severity of ROP in two groups of infants born at less than 29 weeks' gestation who required cryo- or laser therapy. Premature infants born during the first 3 1/2 years following the introduction of surfactant were compared with those born during the 3 1/2-year period prior to its introduction. The infants were examined by one ophthalmologist (J.K.) and classified according to the International Classification of ROP.

RESULTS

A total of 124 infants born presurfactant and 152 infants born postsurfactant were examined for the presence of ROP. No significant difference between the two groups regarding any stage of ROP or the necessity for treatment was found. In infants of less than 27 weeks' gestation, a significant reduction in the number requiring cryo- or laser therapy was noted (12 of 48 examined [25.0%] vs 6 of 62 examined [9.7%], respectively; P < 0.05). This decreased need for treatment, however, was found in infants without hyaline membrane disease who did not receive surfactant.

CONCLUSION

Exosurf has had no significant impact on the incidence or severity of ROP. Due to its effect on improved survival rates, the surfactant produces a larger proportion of infants at risk of developing ROP. Other changes in NICU protocol may be causing a reduction in the incidence of severe ROP.

Bacterial colonization of indwelling vascular catheters in newborn infants

OBJECTIVE

To determine the incidence of bacterial colonization of intravascular catheters, to compare the incidence of colonization of intra-arterial (IA), intravenous (IV) and central venous catheters (CVC), and to determine the association, if any, between catheter withdrawal and bacterial sepsis.

METHODOLOGY

A prospective observational study was carried out at the neonatal intensive care unit of a university-affiliated regional referral centre. A total of 155 catheters (45 IA, 54 IV and 56 CVC) were obtained from 96 infants admitted to the unit and the distal 0.75 cm studied under the scanning electron microscope. The adjoining 0.75 cm was cultured for bacteria.

RESULTS

Scanning electron microscopy revealed that 46% of catheters had bacteria on the internal surface and 13% had bacteria on the outer surface. Greater numbers of CVC were colonized with bacteria compared to IA and IV catheters (P < 0.01). Bacterial colonization of intravascular catheters was not significantly associated with the duration the catheter remained in situ or local reaction at the site of entry of the catheter. Colonization of the external surface of the catheter was significantly associated with bacterial septicaemia (P = 0.0466). Eighty-three per cent of 155 catheters studied had coagulum on the inner or outer surface. Only 53% of these were colonized with bacteria. Bacterial colonization occurred in the absence of a coagulum in only three instances. Catheter withdrawal was not associated with bacterial sepsis. Lack of coagulum on the internal surface of the catheter was strongly associated with septicaemia during the 7 days after catheter withdrawal.

CONCLUSIONS

Although significant numbers of intravascular catheters were colonized with bacteria, only colonization with the external surface was associated with catheter-related sepsis.

Respiratory mechanics before and after late artificial surfactant rescue

OBJECTIVE

To assess the effect of late administration of synthetic surfactant (Exosurf) on the ventilatory function of premature infants with hyaline membrane disease (HMD).

METHODOLOGY

Prospective non-randomized study in the Neonatal Intensive Care Unit (NICU) of a major referral hospital. The patients included two groups of premature infants with a birthweight between 750 and 2000 g who developed HMD. In group 1 with moderate to severe HMD, 2 x 5 mL/kg doses of Exosurf were given 12 h apart (first dose given at a mean age of 18.7 +/- 3.4 h [mean +/- s.e.m.]). In group 2 with milder HMD, no surfactant was given.

RESULTS

Significant reductions (P < 0.05) in the fraction of inspired oxygen (FIO2) occurred 6 h after surfactant administration (24 h of life) and by 48 h (64 h of life) in group 2. These improvements in gas exchange preceded improvements in passive respiratory compliance which occurred 24 h after surfactant (42 h of life) and by 72 h (88 h of life) in group 2 (P < 0.01). In both groups pulmonary resistance increased and was significant (P < 0.05) by 48 h (66 h of life) in group 1.

CONCLUSIONS

Synthetic surfactant given as late as a mean age 18.7 +/- 3.4 h still improves gas exchange but these early improvements cannot be completely explained by modifications of respiratory compliance.

Retinopathy of prematurity in infants less than 29 weeks' gestation at birth

From January 1986 to December 1991 we examined the eyes of 206 infants born at Westmead Hospital, Neonatal Intensive Care Unit who were less than 29 weeks' gestation at birth to determine the incidence of retinopathy of prematurity. Eighty-five infants (41.3%) had no retinopathy of prematurity (ROP) in either eye, 82 infants had stages 1 or 2 ROP (39.8%), 29 had stage 3 ROP (14.1%) and 11 had stage 4 ROP (5.3%). Of these, cryotherapy was performed in 18; six now have bilateral retinal detachment and are blind. The more severe stages of ROP were significantly associated with an increase in the number of days of oxygen supplementation, an increase in the number of days of mechanical ventilation and the presence of patent ductus arteriosus. Infants receiving steroids for mechanical ventilator dependence had a significantly greater chance of requiring cryotherapy (11 or 22 receiving steroids versus seven of 43 without steroids; P < 0.01).

Recovery of tracheal epithelium following high frequency ventilation at low inspired humidity

We used scanning electron microscopy (SEM) and light microscopy (LM) to study the recovery of tracheal epithelium in newborn lambs damaged by high frequency flow interrupted ventilation (HFFIV) at low inspired humidity (30%). Newborn lambs were mechanically ventilated for 6 h, allowed to recover and subsequently killed at 2, 7 or 14 days. The recovery of the trachea above and below the tip of the endotracheal tube (ETT) was studied at these time periods and compared to a control non-intubated group and a group killed immediately after 6 h of ventilation. Above and below the ETT, SEM and LM revealed deciliation to be greatest 2 days after ventilation. The damaged tracheal mucosa had converted to non-ciliated epidermoid squamous metaplastic cells. Recovery was not complete by 14 days, although the squamous cells had already differentiated into goblet and ciliated columnar epithelial cells. No difference was seen in the rate of recovery of the tracheal mucosa above or below the tip of the ETT.

Effect of short-term muscle relaxation on neonatal plasma volume

OBJECTIVES

To study the effect of pancuronium-induced muscle relaxation on circulating plasma volume.

DESIGN

A prospective, controlled study. Consecutive infants who were paralyzed with pancuronium and a comparative group who were not paralyzed during mechanical ventilation were studied.

SETTING

Neonatal ICU of a regional referral university-affiliated hospital.

PATIENTS

Newborn infants weighing greater than 1700 g who required respiratory assistance within 24 hrs of birth and who were free of congenital heart disease, sepsis, or blood loss were eligible for entry into the study. Infants who received colloid infusions during the study period were excluded. A total of 17 consecutive infants (nine paralyzed and eight nonparalyzed control infants) were studied. Four paralyzed infants and one nonparalyzed infant received colloid infusions before the completion of the study and were excluded from the final analysis.

MEASUREMENTS

Plasma volume was measured three times in the paralyzed infants: a) immediately before the first dose of pancuronium, b) after 12 to 24 hrs, and c) greater than or equal to 12 hrs after the return of muscle activity, but before extubation. Plasma volume in the nonparalyzed, control infants was measured at the time of intubation, 12 to 24 hrs after commencing mechanical ventilation, and 12 hrs after extubation. Plasma volume was measured using the Evans blue dye dilution technique.

RESULTS

There were no changes in the plasma volume or blood volume in the three measurements among both the paralyzed and nonparalyzed infants.

CONCLUSION

Pancuronium-induced muscle relaxation in mechanically ventilated newborn infants weighing greater than 1700 g did not alter circulating plasma volume in 24 hrs.

Tracheal damage following conventional and high-frequency ventilation at low and high humidity

OBJECTIVES

To compare the degree of tracheobronchial damage in newborn lambs ventilated for 6 hrs with relative humidities of 30% or 90% and continuous positive airway pressure breathing, conventional mechanical ventilation of 25 and 60 breaths/min, or high frequency flow-interrupted ventilation at 600 breaths/min.

BACKGROUND AND METHODS

Tracheobronchial damage secondary to mechanical ventilation remains a major iatrogenic lesion of the newborn despite substantial advances in both mechanical design and ventilatory techniques. A histologic scoring system was used to compare the damage noted in the tracheobronchial epithelium of newborn lambs after 6 hrs of conventional mechanical ventilation or high-frequency flow-interrupted ventilation at two relative humidities. Three groups of animals were ventilated for 6 hrs with an FIO2 of 0.21 at 36.0 degrees C and relative humidity of 90%. The first group received continuous positive airway pressure of 4 cm H2O, the second group received slow rate, conventional mechanical ventilation at 25 breaths/min, and the third group received fast rate, conventional mechanical ventilation at 60 breaths/min. Two other groups of animals were ventilated for 6 hrs with an FIO2 of 0.21 at 36.0 degrees C and relative humidity of 30%. The first group was ventilated with high-frequency flow-interrupted ventilation at 600 breaths/min and the second group with slow rate, conventional mechanical ventilation at 25 breaths/min. Two additional groups served as nonintubated controls; one group was killed immediately after sedation and the other group was killed after 6 hrs of sedation.

RESULTS

The damage was mild but significantly different from controls when 90% humidity was used and there was no difference in the histology score between continuous positive airway pressure breathing and conventional mechanical ventilation at 25 or 60 breaths/min. Significant inflammation, erosion, necrosis, and blistering occurred with both conventional mechanical ventilation at 25 breaths/min and high-frequency flow-interrupted ventilation at 600 breaths/min when 30% humidity was used. The damage was only found 5 mm below the tip of the endotracheal tube and not at 3.5 cm beyond the endotrachea tube in the trachea nor in the right main bronchus.

CONCLUSION

These data indicate that endotracheal intubation and mechanical ventilation, regardless of the method of ventilation, cause damage to the tracheal mucosa, but that poorly humidified inspired gases cause significantly greater damage.

Epithelial damage beyond the tip of the endotracheal tube

The effects of ventilator rate and inspired humidity on the large airway epithelium of newborn lambs have been studied using scanning electron microscopy. Significant deciliation, denudation and necrosis occurred at both high and conventional rates if the inspired gas had low humidity. The damage observed was mild in the high humidity groups.

Lung injury and repair in rabbits from ventilation with moist air

We pursued previous studies on acute and later effects of different forms of humidification on rabbits' lungs during respiratory support. Arterial wall thickening and alveolar membrane damage was confirmed in the presence of water in the inspired gas. Interstitial collagen was significantly increased 2 weeks later. Though independent of the kind of respiratory support the findings were more pronounced with positive pressure ventilation than with a low continuous pressure with spontaneous breathing. These effects did not occur after humidification with precautions against condensation, and were thus attributable to particulate water. They were interpreted as evidence for lung injury and subsequent repair from this cause. Increased width of small artery walls, possibly from vasoconstriction, was similarly related.

A 15-year survey of chronic lung disease of prematurity

The in-hospital findings for infants of 500-1,500 g birthweight admitted for intensive care over the years 1971-87 were reviewed at four intervals. Survival rate improved substantially. The incidence of chronic lung disease (CLD) in survivors at 28 days of age was unchanged though severity diminished in terms of both mortality and degree of radiographic change. Mean conceptual age for ceasing supplemental oxygen was 32 weeks for those with normal X-rays and 37 weeks for abnormal X-rays regardless of initial degree of immaturity. CLD was diagnosed twice as often when supplemental oxygen beyond 28 days was used as an indicator as against an abnormal X-ray and was hence unreliable for this purpose. Since candidates for CLD are a heterogeneous group care is needed in analysis or selection of material in forming conclusions which concern etiology or management.

Patent ductus arteriosus and retinopathy of prematurity in infants below 27 weeks gestation

Retrospective study of infants who survived the neonatal period after delivery at 24-26 weeks gestation revealed patency of the ductus arteriosus (PDA) in 44%. The mean birthweight of infants who developed PDA was lower. Retinopathy of prematurity (ROP) was seen in 79% of survivors with 24% having grade III or IV involvement. All but one of the more severe grades of ROP occurred among infants with PDA. Infants with PDA required more prolonged ventilatory support. Perinatal factors did not have a significant role in the development of these complications.