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ABSTRACT: A recent systematic review and meta-analysis shows that volume-targeted ventilation (VTV) compared with pressure-limited ventilation (PLV) reduce death and bronchopulmonary dysplasia, pneumothorax, hypocarbia and severe cranial ultrasound abnormalities. In this paper, we present published research and our experience with volume guarantee (VG) ventilation, a VTV mode available on the Dräger Babylog 8000plus and VN500 ventilators. The VG algorithm measures the expired tidal volume (V(T)) for each inflation and adjusts the peak inflating pressure for the next inflation to deliver a V(T) set by the clinician. The advantage of controlling expired V(T) is that this is less influenced by endotracheal tube leak than inspired V(T). VG ventilation can be used with an endotracheal tube leak up to ∼50%. Initial set V(T) for infants with respiratory distress syndrome should be 4.0 to 5.0 ml kg(-1). The set V(T) should be adjusted to maintain normocapnoea. Setting the peak inflating pressure limit well above the working pressure is important to enable the ventilator to deliver the set V(T), and to avoid frequent alarms. This paper provides a practical guide on how to use VG ventilation.
Journal of perinatology: official journal of the California Perinatal Association 07/2011; 31(9):575-85. · 1.59 Impact Factor
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ABSTRACT: The objective of this study is to compare the effects of back-up ventilation rates (BURs) on triggered inflations and patient cardiorespiratory stability during assist-control/volume guarantee ventilation (AC/VG).
This study is a randomized crossover trial conducted in a neonatal unit in an Australian tertiary NICU. In all, 26 stable preterm infants on AC/VG ventilation were studied at BUR settings of 30, 40 and 50 min(-1). Inflation rate, triggering and cardiorespiratory measures of patient stability were compared during 20 min epochs with 10 min washout periods.
The 26 infants studied were median (inter-quartile range) gestational age 27 (26, 30) weeks, birth weight 0.84 (0.75, 1.14) kg and FiO(2) 0.24 (0.21, 0.31) and age 6 (4, 19) days. At BURs of 30, 40 and 50, the proportions of inflations, which were triggered, were mean (s.d.) 85% (11), 75% (19) and 61% (25); P<0.01 for all comparisons. Total delivered inflation rates were 56 (8), 58 (9) and 62 (8) min(-1), respectively. Cardiorespiratory parameters did not vary between the settings.
Using a lower BUR allows greater triggering of ventilator inflations. Cardiorespiratory parameters including CO(2) levels were stable at all rates.
Journal of perinatology: official journal of the California Perinatal Association 06/2011; 32(2):111-6. · 1.59 Impact Factor
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ABSTRACT: Nasal intermittent positive pressure ventilation (NIPPV) may be beneficial but the mechanisms of action are undetermined.
To investigate the effects of non-synchronised NIPPV on spontaneous breathing in premature infants.
10 infants receiving ventilator generated non-synchronised NIPPV were studied for 30 min. Delivered pressure was measured at the nose; respiration was recorded using respiratory inductance plethysmography. Oxygen saturation, carbon dioxide, heart rate, inspired oxygen and video images were recorded.
Median gestational age, birth weight, age and study weight were 25(+3) weeks, 797 g, 24 days and 1076 g. When the NIPPV pressure peak commenced during spontaneous inspiration the inspiratory time increased by 21% (p=0.002), relative tidal volume increased by 15% (p=0.01) and expiratory time was unchanged. When the NIPPV pressure peak commenced during spontaneous expiration the expiratory time increased by 13% (p=0.04). NIPPV pressures delivered during apnoea (range 8-28 cm H(2)O) produced chest inflation 5% of the time, resulting in small tidal volumes (26.7% of spontaneous breath size) but reduced oxygen desaturation. NIPPV pressure peaks occurred throughout spontaneous respiration proportional to the inspiratory: expiratory ratio.
NIPPV pressure peaks only resulted in a small increase in relative tidal volumes when delivered during spontaneous inspiration. During apnoea pressure peaks occasionally resulted in chest inflation, which ameliorated oxygen desaturations. Infants did not become entrained with the NIPPV pressure changes. Synchronising every rise in applied pressure with spontaneous inspiration may increase the effectiveness of NIPPV and warrants investigation.
Archives of Disease in Childhood - Fetal and Neonatal Edition 02/2011; 96(6):F422-8. · 3.05 Impact Factor
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ABSTRACT: Ventilator frequency is one of the determinants of tidal volume delivery during high-frequency ventilation. Clinicians increasingly use data on ventilator displays to inform their decisions.
To measure the frequencies delivered by the Dräger Babylog 8000plus ventilator when used in high-frequency mode.
Ventilator waveforms using a test lung were recorded at the full range of settings 5-20 Hz using Spectra software at 1000 Hz. The changes in frequency produced by a 1-Hz change in set frequency were calculated. Actual and displayed frequencies were compared.
For settings up to 12 Hz, median (range) difference between set and delivered frequencies was 0 (-0.4 to +0.1) Hz. Above 12 Hz, delivered frequency varied by -0.3 (-1.9 to +0.3) Hz. For 1-Hz changes in frequency settings, in the range 5-12 Hz, 1-Hz changes produced a change in delivered frequency of 1.0 (0.6-1.4) Hz. Above 12 Hz, the corresponding changes were 0.7 (0-2.9) Hz. The ventilator displays the set frequency during operation rather than the delivered frequency.
At 12 Hz and below, the differences between set and delivered frequencies were relatively small compared with those at 13 Hz and higher. Above 13 Hz, the difference between set and delivered frequencies was up to 2.9 Hz. Some frequency setting changes did not result in a change in delivered frequency.
Acta Paediatrica 01/2011; 100(1):67-70. · 2.07 Impact Factor
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ABSTRACT: Cerebellar growth in late gestation is impeded by prematurity which may adversely affect neurocognitive development. Assessment of cerebellar growth should be easily attainable, reliable and reproducible.
To assess the reliability of linear sonographic cerebellar vermis measurement.
Cranial ultrasounds of 110 infants ranging from 24 to 41 weeks' gestation were retrospectively reviewed. Cerebellar vermian height, craniocaudal diameter and superior and inferior vermis widths were independently measured on the first midline sagittal image by three neonatal sonologists of varying experience. Interobserver and intraobserver reliability were calculated using the intraclass correlation coefficient (ICC) (2 way mixed model, SPSS V.15.0).
61 images were technically adequate. Interobserver ICCs (95% CI) were: cerebellar vermian height 0.88 (0.82 to 0.92); craniocaudal diameter 0.91 (0.86 to 0.94); superior vermis width 0.84 (0.77 to 0.89); inferior vermis width 0.92 (0.89 to 0.95). Intraobserver ICCs were similar.
With adequate images, linear ultrasound measurements of cerebellar vermis are reliable.
Archives of Disease in Childhood - Fetal and Neonatal Edition 01/2011; 97(4):F307-9. · 3.05 Impact Factor
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Archives of Disease in Childhood - Fetal and Neonatal Edition 09/2010; 95(5):F383. · 3.05 Impact Factor
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ABSTRACT: Nasal intermittent positive pressure ventilation (NIPPV) is a mode of non-invasive respiratory support. Its mechanisms of action and optimal delivery techniques are unknown.
This observational study aimed to investigate and quantify delivered peak pressures during non-synchronised ventilator-generated NIPPV.
Infants born below 30 weeks gestation receiving ventilator-generated NIPPV delivered via Hudson prongs were recruited. Intraprong pressure, change in tidal volume, respiratory rate, oxygen saturations, inspired oxygen and video images were recorded.
Eleven infants (four infants were female) of median (interquartile range; IQR) gestational age 25(+/-3) (25(+/-2) 26(+/-0)) weeks and birth weight 732 (699-895) g, were studied at 24 (19-41) days of age. Six infants, with set peak pressure (peak inflation pressure; PIP) of 20 cm H(2)O, received a median pressure of 15.9 (IQR 13.6-17.9) cm H(2)O. 37% of inflations were delivered at least 5 cm H(2)O below set PIP. 12.7% of inflations were delivered above set PIP. Five infants with set PIP of 25 cm H(2)O received a median PIP of 17.2 (IQR 15.0-18.3) cm H(2)O. 83% of inflations were delivered at least 5 cm H(2)O below set PIP, with 6.1% delivered higher than set PIP. The difference in delivered PIP between the groups was 1.3 cm H(2)O. PIP was highest and most variable when the infant was moving. Delivered PIP did not vary whether it coincided with spontaneous inspiration or expiration.
During ventilator-generated non-synchronised NIPPV delivered PIP was variable and frequently lower than set PIP. Delivered PIP was occasionally greater than set PIP.
Archives of Disease in Childhood - Fetal and Neonatal Edition 09/2010; 95(5):F359-64. · 3.05 Impact Factor
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ABSTRACT: The normal range of heart rate (HR) in the first minutes after birth has not been defined. Objective To describe the HR changes of healthy newborn infants in the delivery room (DR) detected by pulse oximetry. Study Design All inborn infants were eligible and included if a member of the research team attended the birth. Infants were excluded if they received any form of medical intervention in the DR including supplemental oxygen, or respiratory support. HR was measured using a pulse oximeter (PO) with the sensor applied to the right hand or wrist immediately after birth. PO data (oxygen saturation, HR and signal quality) were downloaded every 2 sec and analysed only when the signal had no alarm messages (low IQ signal, low perfusion, sensor off, ambient light). Results Data from 468 infants with 61 650 data points were included. Infants had a mean (range) gestational age of 38 (25-42) weeks and birth weight 2970 (625-5135) g. At 1 min the median (IQR) HR was 96 (65-127) beats per min (bpm) rising at 2 min and 5 min to 139 (110-166) bpm and 163 (146-175) bpm respectively. In preterm infants, the HR rose more slowly than term infants. Conclusions The median HR was <100 bpm at 1 min after birth. After 2 min it was uncommon to have a HR <100 bpm. In preterm infants and those born by caesarean section the HR rose more slowly than term vaginal births.
Archives of Disease in Childhood - Fetal and Neonatal Edition 05/2010; 95(3):F177-81. · 3.05 Impact Factor
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ABSTRACT: Non-invasive respiratory support is increasingly popular but is associated with complications including nasal trauma. The present report describes a novel method of oral continuous positive airway pressure (CPAP) delivery in an extremely premature infant with severe nasal septum erosion. The distal end of a cut down endotracheal tube was passed through a small hole made in the teat of a dummy (infant pacifier) and sutured in place. The dummy was secured in the infant's mouth and CPAP was delivered to the pharynx. The device was well tolerated and the infant was successfully managed using this technique for 48 days, avoiding endotracheal intubation and ventilation.
Archives of Disease in Childhood - Fetal and Neonatal Edition 03/2010; 95(2):F142-3. · 3.05 Impact Factor
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ABSTRACT: Clinical assessment and end-tidal CO(2) (ETCO(2)) detectors are routinely used to verify correct endotracheal tube (ETT) placement. However, ETCO(2) detectors may mislead clinicians by failing to correctly identify placement of an ETT under a variety of circumstances. A flow sensor measures and displays gas flow in and out of an ETT. We compared endotracheal flow sensor recordings with a colorimetric CO(2)-detector (Pedi-Cap) to detect endotracheal intubation in a preterm sheep model of neonatal resuscitation.
Six preterm lambs were intubated and ventilated immediately after delivery. At 5 min the oesophagus was also intubated with a similar tube. The endotracheal tube and oesophageal tubes were attached to a Pedi-Cap and flow sensor in random order. Two observers, blinded to the positions of the tubes, used a ETCO(2) detector and the flow sensor recording to determine whether the tube was in the trachea or oesophagus. The experiment was repeated 10 times for each animal. In the last three animals (30 recordings) the number of inflations required to correctly identify the tube placement was noted.
The Pedi-Cap and the flow sensor correctly identified tube placement in all studies. Thus, the sensitivity, specificity, and positive and negative predictive values of both devices were 100%. At least three, and up to 10, inflations were required to identify tube location with the Pedi-Cap compared to one or two inflations with the flow sensor.
A flow sensor correctly identifies tube placement within the first two inflations. The Pedi-Cap required more inflations to correctly identify tube placement.
Resuscitation 03/2010; 81(6):737-41. · 3.60 Impact Factor
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ABSTRACT: At 12 Hz and below, the differences between set and delivered frequencies were relatively small compared with those at 13 Hz and higher. Above 13 Hz, the difference between set and delivered frequencies was up to 2.9 Hz. Some frequency setting changes did not result in a change in delivered frequency.
Acta paediatrica (Oslo, Norway : 1992). 01/2010; 100:67-70.
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Archives of Disease in Childhood - Fetal and Neonatal Edition 11/2009; 94(6):F467-8; author reply F468; discussion F468. · 3.05 Impact Factor
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ABSTRACT: Extubation failure in premature infants is common. A spontaneous breathing trial (SBT) was prospectively evaluated to determine timing of extubation. Compared with historical controls, infants were extubated at significantly higher ventilator rates and airway pressures using the SBT. No differences in rates of bronchopulmonary dysplasia or duration of ventilation were seen.
Archives of Disease in Childhood - Fetal and Neonatal Edition 08/2008; 93(4):F305-6. · 3.05 Impact Factor
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ABSTRACT: Rupture of the membranes in the second trimester is reported to be associated with high rates of pregnancy loss, neonatal mortality and morbidity. This article describes the outcomes of liveborn infants delivered following a prolonged period of membrane rupture occurring before 24 weeks' gestation.
Over a 5-year period, consecutive pregnancies complicated by spontaneous rupture of the membranes before 24 weeks' gestation were identified. Evaluation of short-term outcomes before discharge of liveborn infants delivered, in a tertiary referral centre, following prolonged rupture of membranes of duration greater than 2 weeks.
Of 98 pregnancies identified with rupture of the membranes before 24 weeks' gestation, 40 (41%) women progressed to deliver a liveborn infant following a latent period of at least 14 days. Although most liveborn infants required neonatal intensive care including mechanical ventilation (n = 38; 78%), the survival rate to hospital discharge was 70% (n = 28). Airleak occurred in 7 (25%) survivors and 8 (67%) deaths. Among the survivors, 12 (43%) required supplemental oxygen at 36 weeks' postmenstrual age and no infant had grade 3 or 4 intraventricular haemorrhage. One infant had a postmortem diagnosis of pulmonary hypoplasia and nine others had clinical features consistent with this diagnosis. Low liquor volume was not uniformly associated with a poor outcome.
With full contemporary neonatal intensive care, the outcome for liveborn infants in the present cohort delivered following membrane rupture occurring before 24 weeks' gestation, of at least 14 days duration, was better than previously reported.
Archives of Disease in Childhood - Fetal and Neonatal Edition 06/2008; 93(3):F207-11. · 3.05 Impact Factor
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ABSTRACT: Less invasive techniques of respiratory support are increasingly popular.
To determine how widespread the use of neonatal nasal intermittent positive airway pressure (NIPPV) has become and describe the range of practice used in NIPPV in England.
95 English Neonatal intensive care units were asked to provide information about NIPPV devices, interfaces, indications, guidelines, use of synchronisation, complications, settings and weaning.
91 (96%) units replied. NIPPV was used by 44/91 (48%) units; few complications were seen. 34/44 (77%) used a synchronising device, 35/44 (80%) used NIPPV for "rescuing" babies for whom continuous positive airway pressure failed-59% routinely after extubation and 16% as a first-line treatment. A wide range of pressure and rate settings were used.
In England, NIPPV is commonly used, with considerable variability in the techniques applied. The wide range of clinical approaches highlights the paucity of evidence available. More evidence is needed to establish best practice.
Archives of Disease in Childhood - Fetal and Neonatal Edition 04/2008; 93(2):F148-50. · 3.05 Impact Factor
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ABSTRACT: Nasal continuous positive airway pressure (NCPAP) is used to support preterm infants recently extubated, those experiencing significant apnoea of prematurity and those with respiratory distress soon after birth as an alternative to intubation and ventilation. This review focuses exclusively on identifying the most effective pressure source and interface for NCPAP delivery in preterm infants.
To determine which technique of pressure generation and which type of nasal interface for NCPAP delivery most effectively reduces the need for additional respiratory support in preterm infants extubated to NCPAP following intermittent positive pressure ventilation (IPPV) for respiratory distress syndrome (RDS) or in those treated with NCPAP soon after birth.
The strategy included searches of MEDLINE (1966 - 2006), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 4, 2006) CINAHL, abstracts from conference proceedings, cross-referencing of previous reviews and the use of expert informants.
Randomised or quasi-randomised trials comparing different techniques of NCPAP pressure generation and/or nasal interfaces in preterm infants extubated to NCPAP following IPPV for RDS or treated with NCPAP soon after birth.
Data was extracted and analysed by the first three authors. Dichotomous results were analysed using the relative risk (RR), risk difference (RD) and number needed to treat (NNT).
1. Preterm infants being extubated to NCPAP following a period of IPPV for RDS:Meta-analysis of the results from Davis 2001 and Roukema 1999a demonstrated that short binasal prongs are more effective at preventing re-intubation than single nasal or nasopharyngeal prongs [typical RR 0.59 (CI: 0.41, 0.85), typical RD -0.21 (CI: -0.35, -0.07), NNT 5 (CI: 3, 14)]. In one study comparing short binasal prong devices (Sun 1999), the re-intubation rate was significantly lower with the Infant Flow Driver than with the Medicorp prong [RR 0.33 (CI: 0.17, 0.67), RD -0.32 (CI: -0.49, -0.15), NNT 3 (CI: 2, 7)]. The other study comparing short binasal prong devices (Infant Flow Driver versus INCA prongs, Stefanescu 2003) demonstrated no significant difference in the re-intubation rate but did show a significant reduction in the total days in hospital in the Infant Flow Driver group [MD -12.60 (95% CI: -22.81, -2.39) days].2. Preterm infants primarily treated with NCPAP soon after birth:In the one trial identified, Mazzella 2001 found a significantly lower oxygen requirement and respiratory rate in those randomised to short binasal prongs when compared with CPAP delivered via nasopharyngeal prong. The requirement for intubation beyond 48 hours from randomisation was not assessed.3. Studies randomising preterm infants to different NCPAP systems using broad inclusion criteriaThe studies of Rego 2002 and Buettiker 2004 did not examine the primary outcomes of this review. Of the secondary outcomes, Rego 2002 demonstrated a significantly higher incidence of nasal hyperaemia with the use of the Argyle prong compared with Hudson prongs [RR 2.39 (95% CI: 1.27, 4.50), RD 0.28 (95% CI: 0.10, 0.46)]. One study comparing different techniques of pressure generation is awaiting further assessment as it is currently available in abstract form only.
Short binasal prong devices are more effective than single prongs in reducing the rate of re-intubation. Although the Infant Flow Driver appears more effective than Medicorp prongs the most effective short binasal prong device remains to be determined. The improvement in respiratory parameters with short binasal prongs suggests they are more effective than nasopharyngeal CPAP in the treatment of early RDS. Further studies incorporating longer-term outcomes are required. Studies are also needed to determine the optimal pressure source for the delivery of NCPAP.
Cochrane database of systematic reviews (Online) 02/2008; · 5.72 Impact Factor
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Archives of Disease in Childhood - Fetal and Neonatal Edition 02/2007; 92(1):F4-7. · 3.05 Impact Factor
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ABSTRACT: Since ancient times many different methods have been used to revive newborns. Although subject to the vagaries of fashion for 2000 years, artificial respiration has been accepted as the mainstay of neonatal resuscitation for about the last 40. Formal teaching programmes have evolved over the last 20 years. The last 10 years have seen international collaboration, which has resulted in careful evaluation of the available evidence and publication of recommendations for clinical practice. There is, however, little evidence to support current recommendations, which are largely based on expert opinion. The challenge for neonatologists today is to gather robust evidence to support or refute these recommendations, thereby refining this common and important intervention.
Archives of Disease in Childhood - Fetal and Neonatal Edition 10/2006; 91(5):F369-73. · 3.05 Impact Factor
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ABSTRACT: To determine the accuracy of three tests used to predict successful extubation of preterm infants.
Mechanically ventilated infants with birth weight <1250 g and considered ready for extubation were changed to endotracheal continuous positive airway pressure (ET CPAP) for three minutes. Tidal volumes, minute ventilation (V e), heart rate, and oxygen saturation were recorded before and during ET CPAP. Three tests of extubation success were evaluated: (a) expired V e during ET CPAP; (b) ratio of V e during ET CPAP to V e during mechanical ventilation (V e ratio); (c) the spontaneous breathing test (SBT)-the infant passed this test if there was no hypoxia or bradycardia during ET CPAP. The clinical team were blinded to the results, and all infants were extubated. Extubation failure was defined as reintubation within 72 hours of extubation.
Fifty infants were studied and extubated. Eleven (22%) were reintubated. The SBT was the most accurate of the three tests, with a sensitivity of 97% and specificity of 73% and a positive and negative predictive value for extubation success of 93% and 89% respectively.
The SBT used just before extubation of infants <1250 g may reduce the number of extubation failures. Further studies are required to establish whether the SBT can be used as the primary determinant of an infant's readiness for extubation.
Archives of Disease in Childhood - Fetal and Neonatal Edition 06/2006; 91(3):F180-3. · 3.05 Impact Factor
