Volume-targeted versus pressure-limited ventilation for preterm infants: a systematic review and meta-analysis

Cell-based therapies for the preterm infant

The severely preterm infant receives a multitude of life-saving interventions, many of which carry risks of serious side effects. Cell therapy is an important and promising arm of regenerative medicine that may address a number of these problems. Most forms of cellular therapy use stem/progenitor cells or stem-like cells, which have the capacity to migrate, engraft and exert anti-inflammatory effects. Although some of these cell-based therapies have made their way to clinical trials in adults, little headway has been made in the neonatal patient group. This review discusses the efficacy of cell therapy in preclinical studies to date and their potential applications to diseases that afflict many prematurely born infants. Specifically, we identify the major hurdles that must be overcome before cell therapies can be safely used in the neonatal intensive care unit.

Early blood gas predictors of bronchopulmonary dysplasia in extremely low gestational age newborns

Aim. To determine among infants born before the 28th week of gestation to what extent blood gas abnormalities during the first three postnatal days provide information about the risk of bronchopulmonary dysplasia (BPD). Methods. We studied the association of extreme quartiles of blood gas measurements (hypoxemia, hyperoxemia, hypocapnea, and hypercapnea) in the first three postnatal days, with bronchopulmonary dysplasia, among 906 newborns, using multivariable models adjusting for potential confounders. We approximated NIH criteria by classifying severity of BPD on the basis of the receipt of any O2 on postnatal day 28 and at 36 weeks PMA and assisted ventilation. Results. In models that did not adjust for ventilation, hypoxemia was associated with increased risk of severe BPD and very severe BPD, while infants who had hypercapnea were at increased risk of very severe BPD only. In contrast, infants who had hypocapnea were at reduced risk of severe BPD. Including ventilation for 14 or more days eliminated the associations with hypoxemia and with hypercapnea and made the decreased risk of very severe BPD statistically significant. Conclusions. Among ELGANs, recurrent/persistent blood gas abnormalities in the first three postnatal days convey information about the risk of severe and very severe BPD.

Understanding neonatal ventilation: strategies for decision making in the NICU

Neonatal ventilation is an integral component of care delivered in the neonatal unit. The aim of any ventilation strategy is to support the neonate's respiratory system during compromise while limiting any long-term damage to the lungs. Understanding the principles behind neonatal ventilation is essential so that health professionals caring for sick neonates and families have the necessary knowledge to understand best practice. Given the range of existing ventilation modes and parameters available, these require explanation and clarification in the context of current evidence. Many factors can influence clinical decision making on both an individual level and within the wider perspective of neonatal care.

Volume-targeted ventilation is more suitable than pressure-limited ventilation for preterm infants: a systematic review and meta-analysis

OBJECTIVE

To assess the effect of volume-targeted ventilation (VTV) compared with pressure-limited ventilation (PLV) in preterm infants.

METHOD

We searched the Cochrane Library (Issue 3, 2013), PubMed (1966 to 5 March 2013), China National Knowledge Infrastructure (CNKI) and periodical databases (1979 to 5 March 2013). We selected randomised controlled trials (RCTs) and quasi-RCTs of VTV versus PLV as active interventions in preterm infants. We performed meta-analyses using the Cochrane statistical package RevMan 5.0.

RESULTS

Eighteen trials met our inclusion criteria. There was no evidence that VTV modes reduced the incidence of death (relative risk (RR) 0.73, 95% CI 0.51 to 1.05). The use of VTV modes resulted in a reduction in the incidence of bronchopulmonary dysplasia (BPD) (RR 0.61, 95% CI 0.46 to 0.82) and duration of mechanical ventilation (mean difference (MD) -2.0 days, 95% CI -3.14 to -0.86). VTV modes also resulted in reductions in intraventricular haemorrhage (IVH) (RR 0.65, 95% CI 0.42 to 0.99), grade 3/4 IVH (RR 0.55, 95% CI 0.39 to 0.79), periventricular leukomalacia (PVL) (RR 0.33, 95% CI 0.15 to 0.72), pneumothorax (RR 0.52, 95% CI 0.29 to 0.93), failure of primary mode of ventilation (RR 0.64, 95% CI 0.43 to 0.94), hypocarbia (RR 0.56, 95% CI 0.33 to 0.96), mean airway pressure (MD -0.54 cmH2O, 95% CI -1.05 to -0.02) and days of supplemental oxygen administration (MD -1.68 days, 95% CI -2.47 to -0.88).

CONCLUSIONS

Preterm infants ventilated using VTV modes had reduced duration of mechanical ventilation, incidence of BPD, failure of primary mode of ventilation, hypocarbia, grade 3/4 IVH, pneumothorax and PVL compared with preterm infants ventilated using PLV modes. There was no evidence that infants ventilated with VTV modes had reduced death compared to infants ventilated using PLV modes.

Anesthesia and long-term outcomes after neonatal intensive care

As survival is now increasing, care of the extremely preterm infant is now directed at strategies to minimize long-term morbidity. In this study, I review the current state-of-the-art outcomes for babies born at extremely low gestations and identify strategies that may be aimed at optimizing outcomes. With respect to anesthetic practice, I then go on to discuss important issues of pain management in these babies and how this may affect long-term outcomes.

Avoiding endotracheal ventilation to prevent bronchopulmonary dysplasia: a meta-analysis

BACKGROUND AND OBJECTIVE

Mechanical ventilation via an endotracheal tube is a risk factor for bronchopulmonary dysplasia (BPD), one of the most common morbidities of very preterm infants. Our objective was to investigate the effect that strategies to avoid endotracheal mechanical ventilation (eMV) have on the incidence of BPD in preterm infants <30 weeks' gestational age (GA).

METHODS

In February 2013, we searched the databases Medline, Embase, and the Cochrane Central Register of Controlled Trials. Study selection criteria included randomized controlled trials published in peer-reviewed journals since the year 2000 that compared preterm infants <30 weeks' GA treated by using a strategy aimed at avoiding eMV with a control group in which mechanical ventilation via an endotracheal tube was performed at an earlier stage. Data were extracted and analyzed by using the standard methods of the Cochrane Neonatal Review Group. The authors independently assessed study eligibility and risk of bias, extracted data and calculated odds ratios and 95% confidence intervals, employing RevMan version 5.1.6.

RESULTS

We identified 7 trials that included a total of 3289 infants. The combined odds ratio (95% confidence interval) of death or BPD was 0.83 (0.71-0.96). The number needed to treat was 35. The study results were remarkably homogeneous. Avoiding eMV had no influence on the incidence of severe intraventricular hemorrhage.

CONCLUSIONS

Strategies aimed at avoiding eMV in infants <30 weeks' GA have a small but significant beneficial impact on preventing BPD.

Neonatal respiratory support strategies in the intensive care unit: an Italian survey

We carried out a survey of current practices of neonatal respiratory support in neonatal intensive care units (NICUs) in Italy with the aim of comparing the current reality with evidence from the literature. We sent a questionnaire by email to the 103 level III neonatal units in Italy. There was a 61 % (73/120) response rate to the questionnaire. We found that synchronized intermittent positive pressure ventilation is mostly used in infants in the acute phase of respiratory distress syndrome (RDS), while the majority of the units prefer volume-targeted ventilation for those in the weaning phase. Nasal continuous positive airway pressure is the most commonly used non-invasive mode of respiratory support, both in the acute and post-extubation phase of RDS. Surfactant is mainly given as rescue treatment. Infants receive caffeine before extubation and analgesia under mechanical ventilation, while post-natal steroids are given after the first week of life in the majority of the units. In conclusion, respiratory support strategies in Italian NICUs are frequently evidence-based. However, since there are areas where this does not occur, we suggest that focused interventions take place on these areas to help improve clinical practice and increase their adherence to evidence-based medical criteria.

Italian survey of neonatal respiratory support strategies

Although the management of respiratory distress syndrome (RDS) in preterm infants has been characterized by significant progress in recent years, it is difficult to translate the research results into clinical practice. Previous surveys have demonstrated that in some areas, the current management of RDS does not reflect evidence from randomized trials. Therefore, the Pulmonology Study Group of the Italian Society of Neonatology decided to perform a similar survey in Italy with the aim of identifying possible aspects of respiratory management of preterm infants with RDS that merit improvement, and of suggesting focused interventions for their resolution.

The journey towards lung protective respiratory support in preterm neonates

The aim of this conceptual review is to provide the reader with a broad perspective on progress made in respiratory support of preterm infants over the past five decades. Landmark discoveries are described in their historical context and underlying theories of lung protection are discussed. The review finishes by integrating different approaches and perspectives into a state-of-the-art concept for lung-protective ventilation in this fragile patient population. Improvements in neonatal respiratory support in the 1970s and 1980s have contributed to dramatic improvements of mortality and morbidity rates among neonates with respiratory failure. Continuous positive airway pressure, antenatal corticosteroids and surfactant replacement therapy revolutionized the care of preterm infants. With the recognition that atelectrauma, volutrauma and oxygen toxicity are the main factors contributing to ventilator-induced lung injury, lung-protective strategies, including noninvasive respiratory support, tidal volume targeting during conventional mechanical ventilation and high frequency ventilation were developed in the 1990s. Given the fact that progress made in the last decade has only resulted in minor improvements in mortality and morbidity rates of neonates with respiratory failure, it seems unlikely that further refinements of current technologies will produce giant leaps forward in high-resource countries. It appears that entirely new approaches would be required. In contrast, knowledge and technology transfer of basic respiratory support strategies (e.g. use of oxygen, simple systems to provide continuous positive airway pressure), could have an enormous impact on the prognosis of neonates with respiratory failure in low-resource countries.

Developing a neonatal unit ventilation protocol for the preterm baby

Mechanical ventilation is a resource-intensive complex medical intervention associated with high morbidity. Considerable practice style variation exists in most hospitals and is not only confusing for parents, but the lack of consistently high standard of optimal ventilation deprives some infants of the benefits of state-of-the-art care. Developing a unit protocol for mechanical ventilation requires exhaustive research, inclusion of all stake-holders, thoughtful protocol development and careful implementation after a thorough educational process, followed by monitoring. A protocol for respiratory support should be comprehensive, addressing respiratory support in the delivery room, the use of non-invasive support, intubation criteria, surfactant administration, specific ventilation modes and settings, criteria for escalating therapy, weaning protocols, extubation criteria, and post-extubation management. Evidence favors the use of non-invasive support as first line treatment, progressing to assist/control or pressure support ventilation combined with volume guarantee, if needed, and high-frequency ventilation only for specific indications. The open lung strategy is crucial to lung-protective ventilation.

Periventricular hemorrhage: a problem still today

Periventricular hemorrhage (PVH) is the result of "temporary" fragile blood vessels and unstable circulation in the brain of very premature infants. Antenatal corticosteroids have substantially reduced PVH. Avoidance of intrapartum hypoxia and birth trauma has probably helped as has better cardio-respiratory stabilization after delivery. Increased survival of the highest risk infants under 26weeks gestation means that there are probably 800-900 infants with severe PVH annually in the UK. Delayed cord clamping could probably reduce PVH further. Various medications can reduce PVH but have not been widely adopted as the imaging has not translated into reduced disability. Posthemorrhagic ventricular dilatation (PHVD) and parenchymal hemorrhagic infarction both greatly increase disability. Treatment of PHVD is based on avoiding pressure and gross distortion of the vulnerable white matter. Further research needs to investigate whether treating subtle seizures, removing blood or blocking free radicals or inflammation will improve prognosis.

Volume-limited and volume-targeted ventilation

This article shows that volume-targeted ventilation is physiologically more logical than pressure-limited ventilation, and is associated with a reduced risk of pneumothorax, hypocarbia, duration of ventilation, death or bronchopulmonary dysplasia, and severe intraventricular hemorrhage. Therefore, it should now be adopted as the main mode for mechanical ventilation of preterm neonates.

Update on the diagnosis and management of bronchopulmonary dysplasia/chronic lung disease of infancy: what the radiologist should know

Pediatric radiologists are frequently called upon to render interpretations of chest radiographs performed on premature infants with chronic respiratory problems. After the acute phase of surfactant deficiency (respiratory distress syndrome), infants with persistent respiratory problems are loosely categorized by clinicians as evolving toward a broad, rather vague entity called bronchopulmonary dysplasia (BPD) or chronic lung disease (CLD). This review aims to update the radiologist on how the characteristics of the disease have shifted and how management, diagnosis and pathology have changed since the disorder was first described more than 40 years ago. The radiologist armed with this information might be better prepared to provide insightful reporting and address the needs of the neonatologist.

Changes in respiratory support of preterm infants in the last decade: are we improving?

BACKGROUND

Ventilator-induced lung injury has been recognized as a major contributing factor for bronchopulmonary dysplasia (BPD) in preterm infants. In the last decade, focus has shifted towards a more gentle respiratory approach.

AIM

To evaluate whether guideline changes in respiratory management in the delivery room and the unit improved the incidence of BPD in very preterm infants.

METHODS

Three cohorts of infants <30 weeks of gestation, born at the Leiden University Medical Center in the Netherlands in 1996-1997 (cohort '96), 2003-2004 (cohort '03) and 2008-2009 (cohort '08), were compared retrospectively. The major change was increasing use of continuous positive airway pressure in time, and monitoring the tidal volume during mechanical ventilation in cohort '08. The primary outcome was BPD at 36 weeks.

RESULTS

The incidence of BPD did not change from 47% in cohort '96 to 55% in cohort '03 (n.s.), but decreased significantly to 37% in cohort '08 (cohort '96 vs. '08 and cohort '03 vs. '08: p < 0.01). We observed the same effect when only moderate and severe BPD were counted with 27% in cohort '96, 31% in cohort '03 and 14% in '08 (cohort '96 vs. '03: p = n.s., cohort '96 vs. '08: p < 0.01, cohort '03 vs. '08: p < 0.05). The mortality rate was not significantly different between the three cohorts.

CONCLUSION

The incidence of BPD in our cohort of preterm infants has decreased during the last decade and could be due to the changes in respiratory management.

A practical guide to neonatal volume guarantee ventilation

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.