"Current concepts in assisted mechanical ventilation in the neonate" - Part 2: Understanding various modes of mechanical ventilation and recommendations for individualized disease-based approach in neonates

Mechanical ventilation is a lifesaving intervention in critically ill preterm and term neonates. However, it has the potential to cause significant damage to the lungs resulting in long-term complications. Understanding the pathophysiological process and having a good grasp of the basic concepts of conventional and high-frequency ventilation is essential for any medical or allied healthcare practitioner involved in the neonates' respiratory management. This review aims to describe the various types and modes of ventilation usually available in neonatal units. It also describes recommendations of an individualized disease-based approach to mechanical ventilation strategies implemented in the authors' institutions.

"Current concepts of mechanical ventilation in neonates" - Part 1: Basics

Mechanical ventilation is potentially live saving in neonatal patients with respiratory failure. The main purpose of mechanical ventilation is to ensure adequate gas exchange, including delivery of adequate oxygenation and enough ventilation for excretion of CO₂. The possibility to measure and deliver small flows and tidal volumes have allowed to develop very sophisticated modes of assisted mechanical ventilation for the most immature neonates, such as volume targeted ventilation, which is used more and more by many clinicians. Use of mechanical ventilation requires a basic understanding of respiratory physiology and pathophysiology of the disease leading to respiratory failure. Understanding pulmonary mechanics, elastic and resistive forces (compliance and resistance), and its influence on the inspiratory and expiratory time constant, and the mechanisms of gas exchange are necessary to choose the best mode of ventilation and adequate ventilator settings to minimize lung injury. Considering the pathophysiology of the disease allows a physiology-based approach and application of these concepts in daily practice for decision making regarding the use of modes and settings of mechanical ventilation, with the ultimate aim of providing adequate gas exchange and minimising lung injury.

Safety and Efficacy of High-Flow Nasal Cannula Therapy in Preterm Infants: A Meta-analysis

BACKGROUND AND OBJECTIVE

High-flow therapy is the most recent, and popular, mode of respiratory support in neonates. However, the evidence supporting its efficacy and safety has not yet been established. We conducted a systematic review and meta-analysis of clinical trials comparing efficacy and safety of high-flow therapy compared with other modes of noninvasive ventilation (NIV) in preterm infants.

METHODS

Articles were indexed by using Medline, Embase, Scopus, OpenSIGLE, Health Management Information Consortium, and Cochrane Central Register of Controlled Trials. Randomized or quasi-randomized clinical trials involving preterm infants, comparing high-flow therapy with other modes of NIV, and reporting extractable data on relevant outcomes, were selected. Data on efficacy, safety, and other common neonatal outcomes were extracted on predesigned forms.

RESULTS

In this analysis, we included 1112 preterm infants, participating in 9 clinical trials. High-flow therapy was similar in efficacy to other modes of NIV in preterm infants when used as primary support (odds ratio of failure of therapy, 1.02 [95% confidence interval: 0.55 to 1.88]), as well as after extubation (1.09 [0.58 to 2.02]). There were no significant differences in odds of death (0.48 [0.18 to 1.24]) between the groups. Preterm infants supported on high-flow had significantly lower odds of nasal trauma (0.13 [0.02 to 0.69]).

CONCLUSIONS

High-flow therapy appears to be similar in efficacy and safety to other conventional modes of NIV in preterm infants. It is associated with significantly lower odds of nasal trauma. Caution needs to be exercised in extreme preterm infants because of the paucity of published data.

Perinatal outcomes and travel time from home to hospital: Welsh data from 1995 to 2009

AIM

To study the association between travel time from home to hospital and birth outcomes.

METHODS

For all registrable births to women resident in Wales (1995-2009), we calculated the travel time between the mother's residence and the postcode-based location for both the birth hospital and all hospitals with maternity services that were open. Using logistic regression, we obtained odds ratios for the association between travel time and each birth outcome, adjusted for confounders.

RESULTS

In our analysis of 412 827 singleton births, for every 15-min increase in travel time to the birth hospital, there was an increased risk of early (n = 609; OR: 1.13; 95%CI: 1.07, 1.20) and late neonatal death (n = 251; OR: 1.15; 95%CI: 1.05, 1.26). Results for intrapartum stillbirth were inconclusive (n = 135; OR: 1.13; 95%CI: 0.98, 1.30). For the above-combined (n = 995) results, we get OR: 1.15, 95%CI: 1.09, 1.20. No association was found with travel time to the nearest hospital (OR: 1.01; 95%CI: 0.90, 1.13 per 15-min increase in travel time) for the composite outcome of intrapartum stillbirth and neonatal deaths.

CONCLUSION

Longer travel time to the birth hospital was associated with increased risk of neonatal deaths, but there was no strong evidence of association with the geographical location of maternity services.

Teenage pregnancy: who suffers?

In this review, we examine the epidemiology of teenage pregnancy (girls aged 15-17 years) in the UK and consider the evidence for its impact on the health and well-being of the mother, the baby, the father and society. There has been some decrease in the teenage pregnancy rate over the last decade in the UK but rates are still considerably higher than those in other European countries. Pregnancy and childbirth during the teenage years are associated with increased risk of poorer health and well-being for both the mother and the baby, possibly reflecting the socio-economic factors that precede early pregnancy and childbirth. There is little evidence concerning the impact of teenage fatherhood on health and future studies should investigate this. The effect on society is a perpetuation of the widening gap in health and social inequalities. Public health interventions should aim to identify teenagers who are vulnerable and support those who are pregnant with evidence based interventions such as teenage antenatal clinics and access to initiatives that provide support for early parenthood.

Perinatal and infant autopsy

OBJECTIVES

To measure perinatal and infant autopsy rate in Wales over a 10-year period and study factors influencing the decision to perform an autopsy.

DESIGN

Retrospective cohort analysis of data from the All Wales Perinatal Survey.

METHODS

Autopsy rates were calculated over a 10-year period (1994-2003), and reasons for not performing an autopsy were noted. Two time periods, 1994-1996 and 2001-2003 were compared, to study changing autopsy patterns.

RESULTS

Over the 10-year period, there were 4393 perinatal and infant deaths, with data available for 4306 (98%) cases. Consent for autopsy was requested in 89% of cases and granted in 68%. When compared, the 3-year cumulative autopsy rate fell from 67.5% (95% confidence interval (CI) 65% to 69%) in 1994-1996, to 52.7% (CI 49% to 55%) in 2001-2003. The difference in the proportion of autopsies performed between the two time periods was 14.8% (CI 11% to 18%). Parental consent was granted in 76.2% (CI 73% to 78%) of cases in 1994-1996 and 60% (CI 57% to 63%) of cases in 2001-2003. The difference in proportion in consent for autopsy in the two time periods was 16% (CI 12% to 20%).

CONCLUSIONS

A decrease in perinatal and infant autopsy rates has been found in Wales over the past 10 years. Parental refusal has been the main cause of this decline.

Measurement of urine output by weighing nappies

The effect of humidity on measurement of neonatal urine output was assessed by weighing nappies in a clinically relevant context. Saline was used as dummy urine, on modern nappies in incubators at various humidity settings. In at least some additional humidity, no clinically relevant evaporative loss occurred.