Vadivelam Murthy

Conventional Mechanical Ventilation Versus High-frequency Oscillatory Ventilation for Congenital Diaphragmatic Hernia: A Randomized Clinical Trial (The VICI-trial).

Objectives:To determine the optimal initial ventilation mode in congenital diaphragmatic hernia. Background:Congenital diaphragmatic hernia is a life-threatening anomaly with significant mortality and morbidity. The maldeveloped lungs have a high susceptibility for oxygen and ventilation damage resulting in a high incidence of bronchopulmonary dysplasia (BPD) and chronic respiratory morbidity. Methods:An international, multicenter study (NTR 1310), the VICI-trial was performed in prenatally diagnosed congenital diaphragmatic hernia infants (n = 171) born between November 2008 and December 2013, who were randomized for initial ventilation strategy. Results:Ninety-one (53.2%) patients initially received conventional mechanical ventilation and 80 (46.8%) high-frequency oscillation. Forty-one patients (45.1%) randomized to conventional mechanical ventilation died/ had BPD compared with 43 patients (53.8%) in the high-frequency oscillation group. An odds ratio of 0.62 [95% confidence interval (95% CI) 0.25–1.55] (P = 0.31) for death/BPD for conventional mechanical ventilation vs high-frequency oscillation was demonstrated, after adjustment for center, head-lung ratio, side of the defect, and liver position. Patients initially ventilated by conventional mechanical ventilation were ventilated for fewer days (P = 0.03), less often needed extracorporeal membrane oxygenation support (P = 0.007), inhaled nitric oxide (P = 0.045), sildenafil (P = 0.004), had a shorter duration of vasoactive drugs (P = 0.02), and less often failed treatment (P = 0.01) as compared with infants initially ventilated by high-frequency oscillation. Conclusions:Our results show no statistically significant difference in the combined outcome of mortality or BPD between the 2 ventilation groups in prenatally diagnosed congenital diaphragmatic hernia infants. Other outcomes, including shorter ventilation time and lesser need of extracorporeal membrane oxygenation, favored conventional ventilation.

End tidal carbon dioxide levels during the resuscitation of prematurely born infants.

BACKGROUND Successful resuscitation of prematurely born infants is dependent on achieving adequate alveolar ventilation and vasodilation of the pulmonary vascular bed. Elevation of end-tidal carbon dioxide (ETCO(2)) levels may indicate pulmonary vasodilation. AIMS This research aims to study the temporal changes in ETCO(2) levels and the infants respiratory efforts during face mask resuscitation in the labour suite, and to determine if the infants first inspiratory effort was associated with a rise in the ETCO(2) levels, suggesting pulmonary vasodilation had occurred. STUDY DESIGN This study is an observational one. SUBJECTS The subjects of the study are forty infants with a median gestational age of 30 weeks (range 23-34). OUTCOME MEASURES Inflation pressures, expiratory tidal volumes and ETCO(2) levels were measured. RESULTS The median expiratory tidal volume of inflations prior to the onset of the infants respiratory efforts (passive inflations) was lower than that of the inflation associated with the first inspiratory effort (active inflation) (1.8 (range 0.1-7.3) versus 6.3 ml/kg (range 1.9-18.4), p<0.001), as were the median ETCO(2) levels (0.3 (range 0.1-2.1) versus 3.4 kPa (0.4-11.5), p<0.001). The median expiratory tidal volume (4.5 ml/kg (range 0.5-18.3)) and ETCO(2) level (2.2 kPa (range 0.3-9.3)) of the two passive inflations following the first active inflation were also higher than the median expiratory tidal volume and ETCO(2) levels of the previous passive inflations (p<0.001, p<0.0001 respectively). CONCLUSION These results suggest that during face mask resuscitation, improved carbon dioxide elimination, likely due to pulmonary vasodilation, occurred with the onset of the infants respiratory efforts.

Survey of UK newborn resuscitation practices.

Surveys of newborn resuscitation practices1,–,4 have revealed differences between and in countries, but the equipment and techniques used in the UK are guided by the UK Resuscitation Council, and staff involved must undertake a newborn life support course. We hypothesised, therefore, that in the UK there would be consistency of practice regardless of the level of neonatal care, and our aim was to test this hypothesis. A questionnaire was sent to the lead paediatrician of 212 hospitals with newborn units. Differences in resuscitation practices according to the level of neonatal care were assessed for statistical significance using the χ2 test. There was an 85% response. …

The first five inflations during resuscitation of prematurely born infants

Objective To study the first five inflations during the resuscitation of prematurely born infants and whether the infants inspiratory efforts influenced the expired tidal volume. Design Prospective observational study. Setting Two tertiary perinatal centres. Patients Thirty infants, median gestational age 30 (23–34) weeks. Interventions The first five inflations delivered via a face mask and t-piece device were examined using respiratory function monitoring. Main outcome measures Inflation pressures, inflation times and expiratory volumes were recorded and comparison made of inflations during which the infant made an inspiratory effort (active inflation) or did not (passive inflation). Results Overall, the median expired tidal volume was 2.5 (0–19.8) ml/kg and was lower for passive (median 2.1 ml/kg, range 0–19.8 ml/kg) compared with active (median 5.6 ml/kg, range 1.2–12.2 ml/kg) inflations (ratio of geometric means 1.85, 95% CI 1.18 to 28%) (p=0.007). Overall, the median face mask leak was 54.5% and was lower for active (34.5%) compared with passive (60.7%) inflations (mean difference in % leak: 12.4%, 95% CI 0.9 to 24%) (p=0.0354). There was a significant positive correlation between the expiratory volumes and the inflation pressures (R2 between subjects 0.19, p=0.04) and a negative correlation between the expiratory tidal volumes and the face mask leaks (R2 between subjects=0.051, p<0.001), but there was no significant correlation between the inflation times and the expiratory tidal volumes. Conclusion The expired tidal volume, inflation pressures and times during the first five inflations during resuscitation were variable. The expired tidal volumes were significantly greater if the infant inspired during the inflation.

Neuromuscular Blockade and Lung Function during Resuscitation of Infants with Congenital Diaphragmatic Hernia

Background: There is no consensus or evidence as to whether a neuromuscular blocking agent should be used during the initial resuscitation of infants with congenital diaphragmatic hernia (CDH) in the labour ward. Objective: To determine if administration of a neuromuscular blocking agent affected the lung function of infants with CDH during their initial resuscitation in the labour ward. Methods: Fifteen infants with CDH were studied (median gestational age 38 weeks, range 34–41; birth weight 2,790 g, range 1,780–3,976). Six infants had undergone feto-endotracheal occlusion (FETO). Flow, airway pressure, tidal volume and dynamic lung compliance changes were recorded using a respiratory function monitor (NM3, Respironics). Twenty inflations immediately before, immediately after and 5 min after administration of a neuromuscular blocking agent (pancuronium bromide) were analysed. Results: The median dynamic lung compliance of the 15 infants was 0.22 ml/cm H2O/kg (range 0.1–0.4) before and 0.16 ml/cm H2O/kg (range 0.1–0.3) immediately after pancuronium bromide administration (p < 0.001) and remained at a similar low level 5 min after pancuronium bromide administration. The FETO compared to the non-FETO infants had a lower median dynamic compliance both before (p < 0.0001) and 5 min after pancuronium administration (p < 0.001) and required significantly longer durations of ventilation (p = 0.004), supplementary oxygen (p = 0.003) and hospitalisation (p = 0.007). Conclusions: Infants with CDH, particularly those who have undergone FETO, have a low lung compliance at birth, and this is further reduced by administration of a neuromuscular blocking agent.

Randomised weaning trial comparing assist control to pressure support ventilation

Objectives To determine if the work of breathing was lower, respiratory muscle strength greater, but the degree of asynchrony higher during weaning by assist control ventilation (ACV) rather than pressure support ventilation (PSV) and if any differences were associated with a shorter duration of weaning. Design Randomised trial Setting Tertiary neonatal unit Patients Thirty-six infants, median gestational age 29 (range 24 to 39) weeks Intervention Weaning by either ACV or PSV. Main outcome measures At baseline, 24 hours after entering the study and immediately prior to extubation, the work of breathing (PTPdi), thoracoabdominal asynchrony (TAA) and respiratory muscle strength (Pimax) were assessed and weaning duration recorded. Results There were no significant differences in the median PTPdi, TAA and Pimax results at any time point. The inflation times during ACV and PSV were similar. The median duration of weaning was 34 (range 7–100) hours in the ACV group and 27 (range 10–169) hours in the PSV group (p=0.88). Conclusion No significant differences were found between weaning by PSV and ACV when similar inflation times were used.

RESPIRATORY DISTRESS SYNDROME

Respiratory Distress Syndrome (RDS) is due to immaturity of the lungs, primarily the surfactant synthesising system; hence, the risk of RDS is inversely proportional to gestational age. The incidence of RDS has been reduced by the routine use of both antenatal corticosteroids and postnatal surfactant, but still approximately one per cent of babies develop RDS. Hyaline membranes, formed from plasma proteins which have leaked onto the lung surface through damaged capillaries and endothelial cells, line the terminal airways. Hence, RDS has also been called hyaline membrane disease, but RDS is the preferred name as the presence of hyaline membranes can only be confirmed histologically. The aim of this review is to emphasize the pathophysiology of RDS and the clinical presentation and relevance of diagnostic techniques in the current population of very prematurely born infants, highlighting the differential diagnosis. In addition, the evidence base for prophylactic and management strategies including whether new therapies and techniques of respiratory support have positively impacted on outcomes are discussed. The mortality and long term morbidity associated with very premature birth are described. Our increasing understanding that the so-called new bronchopulmonary dysplasia (BPD) and associated chronic adverse respiratory outcomes in such infants can reflect antenatal events resulting in abnormal lung growth is highlighted.

The first breath during resuscitation of prematurely born infants.

BACKGROUND The first five initial inflation pressures and times during resuscitation of prematurely born infants are frequently lower than those recommended and rarely result in tidal volumes exceeding the anatomical dead space. Greater volumes were produced when the infant was provoked to inspire by an inflation (active inflation). AIMS To assess factors associated with a shorter time to the first active inflation. STUDY DESIGN Respiratory function monitoring was undertaken during resuscitation, peak inflation pressures (PIP), inflation times and the infants respiratory activity were simultaneously recorded. SUBJECTS Infants with a gestational age<34weeks requiring resuscitation at birth. OUTCOME MEASURES The relationships of the PIP and inflation time of the first five inflations and first active inflation to the time to the first active inflation. RESULTS Recordings from 47 infants, median gestational age of 29 (23-34) weeks, were analysed. The median PIP of the first five inflations was 27 (range 9-37) cmH2O and inflation time 1.22 (range 0.32-4.08) s. The median PIP of the first active inflation was 25 (range 19-37) cmH2O and inflation time 1.35 (0.35-3.67) s. The median time to the first active inflation was 7 (range 0-50) seconds and was inversely correlated with the PIP (p=0.001) and inflation time (p=0.018) of the first five inflations and the PIP (p=0.001) and inflation time (p=0.008) of the first active inflation. CONCLUSION The magnitude of the inflation pressures and times of the first five inflations inversely correlate with the time to the first breath during resuscitation.

G104 Inflation pressures and times during the resuscitation of prematurely born infants

Aim We have previously demonstrated that using the UK recommended inflation pressures (20/5 cmH2O) for the first five inflations, expiratory tidal volumes (TVe) rarely exceeded the anatomical dead space (1) and end tidal carbon dioxide (CO2) levels were low (2). The inflation times, however, were usually much shorter than recommended.1,2 Our aim was to assess the effects of higher inflation pressures and longer inflation times. Methods The responses to the first five inflations of infants of gestational age < 34 weeks resuscitated via a face mask were studied. Infants resuscitated using peak inflation pressures of 25 cmH2O and short (<1.5 seconds) or long (>1.5 seconds) inflation times were matched by gestational age to infants resuscitated with peak pressures of 20 cmH2O with short or long inflation times. A NM3 respiratory profile monitor was used to record the inflation pressures, flow, tidal volumes and end tidal CO2 levels. Active inflations were excluded from the analysis. Results There were 12 infants in each of the four groups; the median gestational age of the infants was 31 (range 24–34) weeks. Infants resuscitated with short inflation times had higher expiratory tidal volumes when resuscitated at 25/5 cmH2O compared to 20/5 cmH2O (0.12 (range 0.10–6.8) mls/kg versus 3.21 (range 0.16 –12.20) mls/kg respectively), p= <0.001 and higher ETCO levels (2.05 (range 0.2–35.6) mm Hg versus 8.30 (range 0.3 –61) mm Hg respectively), p = 0.030. Infants resuscitated with long inflation times had higher expiratory tidal volumes when resuscitated at 25/5 cmH2O compared to 20/5 cmH2O (2.06 (range 0.18–13.2) mls/kg versus 1.94 (range 0.01–8.4) mls/kg respectively), p = 0.011, but similar ETCO levels. Conclusion Increasing inflation pressures from 20/5 to 25/5 cmH2O improved tidal volumes regardless of the inflation time used. References Murthy V, Dattani N, Peacock JL, Fox GF, Campbell ME, Milner AD, Greenough A. The first five inflations during resuscitation of prematurely born infants. Arch Dis Child Fetal Neonatal Ed 2012 97: F249-F253 Murthy V, O’Rourke–Potocki A, Dattani N, Fox GF, Campbell ME, Milner AD, Greenough A. End tidal carbon dioxide levels during the resuscitation of prematurely born infants. Early Hum Dev 2012 Oct; 88(10):783-7.

Detection of exhaled carbon dioxide following intubation during resuscitation at delivery

Objectives End tidal carbon dioxide (ETCO2) monitoring can facilitate identification of successful intubation. The aims of this study were to determine the time to detect ETCO2 following intubation during resuscitation of infants born prematurely and whether it differed according to maturity at birth or the Apgar scores (as a measure of the infant’s condition after birth). Design Analysis of recordings of respiratory function monitoring. Setting Two tertiary perinatal centres. Patients Sixty-four infants, with median gestational age of 27 (range 23–34)weeks. Interventions Respiratory function monitoring during resuscitation in the delivery suite. Main outcome measures The time following intubation for ETCO2 levels to be initially detected and to reach 4 mm Hg and 15 mm Hg. Results The median time for initial detection of ETCO2 following intubation was 3.7 (range 0–44) s, which was significantly shorter than the median time for ETCO2 to reach 4 mm Hg (5.3 (range 0–727) s) and to reach 15 mm Hg (8.1 (range 0–827) s) (both P<0.001). There were significant correlations between the time for ETCO2 to reach 4 mm Hg (r=−0.44, P>0.001) and 15 mm Hg (r=−0.48, P<0.001) and gestational age but not with the Apgar scores. Conclusions The time for ETCO2 to be detected following intubation in the delivery suite is variable emphasising the importance of using clinical indicators to assess correct endotracheal tube position in addition to ETCO2 monitoring. Capnography is likely to detect ETCO2 faster than colorimetric devices.