High frequency oscillatory ventilation versus conventional ventilation for infants with severe pulmonary dysfunction born at or near term

Hemodynamic effects of high frequency oscillatory ventilation with volume guarantee in a piglet model of respiratory distress syndrome

Respiratory failure is a common condition faced by critically ill neonates with respiratory distress syndrome (RDS). High frequency oscillatory ventilation (HFOV) is often used for neonates with refractory respiratory failure related to RDS. Volume guarantee (VG) mode has been added to some HFOV ventilators for providing consistent tidal volume. We sought to examine the impact of adding the VG mode during HFOV on systemic and cerebral hemodynamics, which has not been studied to date. A neonatal piglet model of moderate to severe RDS was induced by saline lavage. Piglets (full term, age 1–3 days, weight 1.5–2.4 kg) were randomized to have RDS induced and receive either HFOV or HFOV+VG (n = 8/group) or sham-operation (n = 6) without RDS. Cardiac function measured by a Millar^® catheter placed in the left ventricle as well as systemic and carotid hemodynamic and oxygen tissue saturation parameters were collected over 240 min of ventilation. Mean airway pressure, alveolar-arterial oxygen difference and left ventricular cardiac index of piglets on HFOV vs. HFOV+VG were not significantly different during the experimental period. Right common carotid artery flow index by in-situ ultrasonic flow measurement and cerebral tissue oxygen saturation (near-infrared spectroscopy) significantly decreased in HFOV+VG at 240 min compared to HFOV (14 vs. 31 ml/kg/min, and 30% vs. 43%, respectively; p<0.05). There were no significant differences in lung, brain and heart tissue markers of oxidative stress, ischemia and inflammation. HFOV+VG compared to HFOV was associated with similar left ventricular function, however HFOV+VG had a negative effect on cerebral blood flow and oxygenation.

Consideration of the respiratory support strategy of severe acute respiratory failure caused by SARS-CoV-2 infection in children

The recent ongoing outbreak of severe pneumonia associated with a novel coronavirus (SARS-CoV-2), currently of unknown origin, creates a world emergency that has put global public health institutions on high alert. At present there is limited clinical information of the SARS-CoV-2 and there is no specific treatment recommended, although technical guidances and suggestions have been developed and will continue to be updated as additional information becomes available. Preventive treatment has an important role to control and avoid the spread of severe respiratory disease, but often is difficult to obtain and sometimes cannot be effective to reduce the risk of deterioration of the underlining lung pathology. In order to define an effective and safe treatment for SARS-CoV-2-associated disease, we provide considerations on the actual treatments, on how to avoid complications and the undesirable side effects related to them and to select and apply earlier the most appropriate treatment. Approaching to treat severe respiratory disease in infants and children, the risks related to the development of atelectasis starting invasive or non-invasive ventilation support and the risk of oxygen toxicity must be taken into serious consideration. For an appropriate and effective approach to treat severe pediatric respiratory diseases, two main different strategies can be proposed according to the stage and severity of the patient conditions: patient in the initial phase and with non-severe lung pathology and patient with severe initial respiratory impairment and/or with delay in arrival to observation. The final outcome is strictly connected with the ability to apply an appropriate treatment early and to reduce all the complications that can arise during the intensive care admission.

Consideration of the respiratory support strategy of severe acute respiratory failure caused by SARS-CoV-2 infection in children

The recent ongoing outbreak of severe pneumonia associated with a novel coronavirus (SARS-CoV-2), currently of unknown origin, creates a world emergency that has put global public health institutions on high alert. At present there is limited clinical information of the SARS-CoV-2 and there is no specific treatment recommended, although technical guidances and suggestions have been developed and will continue to be updated as additional information becomes available. Preventive treatment has an important role to control and avoid the spread of severe respiratory disease, but often is difficult to obtain and sometimes cannot be effective to reduce the risk of deterioration of the underlining lung pathology. In order to define an effective and safe treatment for SARS-CoV-2-associated disease, we provide considerations on the actual treatments, on how to avoid complications and the undesirable side effects related to them and to select and apply earlier the most appropriate treatment. Approaching to treat severe respiratory disease in infants and children, the risks related to the development of atelectasis starting invasive or non-invasive ventilation support and the risk of oxygen toxicity must be taken into serious consideration. For an appropriate and effective approach to treat severe pediatric respiratory diseases, two main different strategies can be proposed according to the stage and severity of the patient conditions: patient in the initial phase and with non-severe lung pathology and patient with severe initial respiratory impairment and/or with delay in arrival to observation. The final outcome is strictly connected with the ability to apply an appropriate treatment early and to reduce all the complications that can arise during the intensive care admission.

High-frequency oscillatory ventilation: A narrative review

High-frequency oscillatory ventilation (HFOV) is a lung-protective strategy that can be utilized in the full spectrum of patient populations ranging from neonatal to adults with acute lung injury. HFOV is often utilized as a rescue strategy when conventional mechanical ventilation (CV) has failed. HFOV uses low tidal volumes and constant mean airway pressures in conjunction with high respiratory rates to provide beneficial effects on oxygenation and ventilation, while eliminating the traumatic “inflate–deflate” cycle imposed by CV. Although statistical evidence supporting HFOV is particularly low, potential benefits for its application in many clinical manifestations still remain. High-frequency oscillation is a safe and effective rescue mode of ventilation for the treatment of acute respiratory distress syndrome (ARDS). All patients who have ventilator-induced lung injury (VILI) or are at risk of developing VILI or ARDS would be suitable candidates for HFOV, especially those who have failed conventional mechanical ventilation. This narrative aims to provide a review of HFOV vis-à-vis its indications, contraindications, hazards, parameters to monitoring, patient selection, clinical goals, mechanisms of action, controls for optimizing ventilation and oxygenation, clinical application in ARDS, and a comparison with other modes of mechanical ventilation.

[Clinical effects of different ways of mechanical ventilation combined with pulmonary surfactant in treatment of acute lung injury/acute respiratory distress syndrome in neonates: a comparative analysis]

OBJECTIVE

To compare the therapeutic effects of high-frequency oscillatory ventilation+pulmonary surfactant (HFOV+PS), conventional mechanical ventilation+pulmonary surfactant (CMV+PS), and conventional mechanical ventilation (CMV) alone for acute lung injury/acute respiratory distress syndrome (ALI/ARDS) in neonates.

METHODS

A total of 136 neonates with ALI/ARDS were enrolled, among whom 73 had ALI and 63 had ARDS. They were divided into HFOV+PS group (n=45), CMV+PS group (n=53), and CMV group (n=38). The neonates in the first two groups were given PS at a dose of 70-100 mg/kg. The partial pressure of oxygen (PaO₂), partial pressure of carbon dioxide (PaCO₂), PaO₂/fraction of inspired oxygen (FiO₂), oxygenation index (OI), and respiratory index (RI) were measured at 0, 12, 24, 48, and 72 hours of mechanical ventilation.

RESULTS

At 12, 24, and 48 hours of mechanical ventilation, the HFOV+PS group had higher PaO₂ and lower PaCO₂ than the CMV+PS and CMV groups (P<0.05). At 12, 24, 48, and 72 hours of mechanical ventilation, the HFOV+PS group had higher PaO₂/FiO₂ and lower OI and RI than the CMV+PS and CMV groups (P<0.05). The HFOV+PS group had shorter durations of mechanical ventilation and oxygen use than the CMV+PS and CMV groups (P<0.05). There were no significant differences in the incidence rates of air leakage and intracranial hemorrhage and cure rate between the three groups.

CONCLUSIONS

In neonates with ALI/ARDS, HFOV combined with PS can improve pulmonary function more effectively and shorten the durations of mechanical ventilation and oxygen use compared with CMV+PS and CMV alone. It does not increase the incidence of complications.

Infant position in neonates receiving mechanical ventilation

BACKGROUND

In patients of various ages undergoing mechanical ventilation (MV), it has been observed that positions other than the standard supine position, such as the prone position, may improve respiratory parameters. The benefits of these positions have not been clearly defined for critically ill newborns receiving MV.This is an update of a review first published in 2005 and last updated in 2013.

OBJECTIVES

Primary objectiveTo assess the effects of different positioning of newborn infants receiving MV (supine vs prone, lateral decubitus or quarter turn from prone) in improving short-term respiratory outcomes. Secondary objectiveTo assess the effects of different positioning of newborn infants receiving MV on mortality and neuromotor and developmental outcomes over the long term, and on other complications of prematurity.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 8), MEDLINE via PubMed (1966 to 22 August 2016), Embase (1980 to 22 August 2016) and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to 22 August 2016). We also searched clinical trials databases, conference proceedings and reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials.

SELECTION CRITERIA

Randomised and quasi-randomised clinical trials comparing different positions in newborns receiving mechanical ventilation.

DATA COLLECTION AND ANALYSIS

Three unblinded review authors independently assessed trials for inclusion in the review and extracted study data. We used standard methodological procedures as expected by The Cochrane Collaboration and assessed the quality of the evidence using the GRADE approach. If the meta-analysis was not appropriate owing to substantial clinical heterogeneity between trials, we presented review findings in narrative format.

MAIN RESULTS

We included in this review 19 trials involving 516 participants. Seven of the included studies (N = 222) had not been evaluated in the previous review. Investigators compared several positions: prone versus supine, prone alternant versus supine, prone versus lateral right, lateral right versus supine, lateral left versus supine, lateral alternant versus supine, lateral right versus lateral left, quarter turn from prone versus supine, quarter turn from prone versus prone and good lung dependent versus good lung uppermost.Apart from two studies that compared lateral alternant versus supine, one comparing lateral right versus supine and two comparing prone or prone alternant versus the supine position, all included studies had a cross-over design. In five studies, infants were ventilated with continuous positive airway pressure (CPAP); in the other studies, infants were treated with conventional ventilation (CV).Risks of bias did not differ substantially for different comparisons and outcomes. This update detects a moderate to high grade of inconsistency, similar to previous versions. However, for the analysed outcomes, the direction of effect was the same in all studies. Therefore, we consider that this inconsistency had little effect on the conclusions of the meta-analysis. When comparing prone versus supine position, we observed an increase in arterial oxygen tension (PO₂) in the prone position (mean difference (MD) 5.49 mmHg, 95% confidence interval (CI) 2.92 to 8.05 mmHg; three trials; 116 participants; I²= 0). When percent haemoglobin oxygen saturation was measured with pulse oximetry (SpO₂), improvement in the prone position was between 1.13% and 3.24% (typical effect based on nine trials with 154 participants; I²= 89%). The subgroup ventilated with CPAP (three trials; 59 participants) showed a trend towards improving SpO2 in the prone position compared with the supine position, although the mean difference (1.91%) was not significant (95% CI -1.14 to 4.97) and heterogeneity was extreme (I²= 95%).Sensitivity analyses restricted to studies with low risk of selection bias showed homogeneous results and verified a small but significant effect (MD 0.64, 95% CI 0.26 to 1.02; four trials; 92 participants; I²= 0).We also noted a slight improvement in the number of episodes of desaturation; it was not possible to establish whether this effect continued once the intervention was stopped. Investigators studied few adverse effects from the interventions in sufficient detail. Two studies analysed tracheal cultures of neonates after five days on MV, reporting lower bacterial colonisation in the alternating lateral position than in the supine posture. Other effects - positive or negative - cannot be excluded in light of the relatively small numbers of neonates studied.

AUTHORS' CONCLUSIONS

This update of our last review in 2013 supports previous conclusions. Evidence of low to moderate quality favours the prone position for slightly improved oxygenation in neonates undergoing mechanical ventilation. However, we found no evidence to suggest that particular body positions during mechanical ventilation of the neonate are effective in producing sustained and clinically relevant improvement.

High frequency jet ventilation versus high frequency oscillatory ventilation for pulmonary dysfunction in preterm infants

BACKGROUND

Respiratory distress syndrome (RDS) is considered one of the major contributors to severe pulmonary dysfunction and consequent death in preterm infants. Despite widespread improvements in care, including increased utilization of antenatal steroids, use of surfactant replacement therapy, and advances in conventional mechanical ventilation (CMV), chronic lung disease (CLD) occurs in 42% of surviving preterm infants born at less than 28 weeks gestational age (GA). High frequency ventilation (HFV) aims to optimize lung expansion while minimizing tidal volume (Vt) to decrease lung injury. Two methods of HFV - high frequency oscillatory ventilation (HFOV) and high frequency jet ventilation (HFJV) - are widely used, but neither has demonstrated clear superiority in elective or rescue mode.

OBJECTIVES

To compare the benefits and side effects of HFJV versus HFOV for mortality and morbidity in preterm infants born at less than 37 weeks GA with pulmonary dysfunction in both elective and rescue modes.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 11), MEDLINE via PubMed (1966 to November 30, 2015), EMBASE (1980 to November 30, 2015), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982 to November 30, 2015). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomized controlled trials and quasi-randomized trials. We imposed no date, language, or publication restrictions.

SELECTION CRITERIA

We planned to include randomized, cluster-randomized, and quasi-randomized controlled trials if study authors stated explicitly that groups compared in the trial were established by a random or systematic method of allocation. We planned to exclude cross-over studies, as they would not allow assessment of the outcomes of interest.

DATA COLLECTION AND ANALYSIS

We used the standard methods of the Neonatal Cochrane Review Group, including independent trial assessment and data extraction. We intended to analyze the data by using risk ratios (RRs) and risk differences (RDs) and 1/RD. We planned to calculate the number needed to treat for an additional beneficial outcome (NNTB) or the number needed to treat for an additional harmful outcome (NNTH).

MAIN RESULTS

We found no studies that met our inclusion criteria.

AUTHORS' CONCLUSIONS

We found no evidence to support the superiority of HFJV or HFOV as elective or rescue therapy. Until such evidence is available, comparison of potential side effects or presumed benefits of either mode is not feasible.

Congenital diaphragmatic hernia, management in the newborn

Congenital diaphragmatic hernia (CDH) in the newborn poses challenges to the multi-disciplinary teams involved in its management. Mortality remains significantly high, despite growing understanding and treatment options. Early intubation of antenatally diagnosed cases is crucial in preventing deterioration and persistent pulmonary hypertension. Early recognition of cases not diagnosed on antenatal scan, with appreciation of differential diagnosis, requires an index of suspicion and imaging. Increasing options and modalities are available, with only modest, if any, survival advantage. Permissive hypercapnea and minimal ventilation have made the most significant impact on survival in modern era. High-frequency oscillatory ventilation (HFOV), inhaled nitric oxide (iNO), treatment of pulmonary hypertension, and ECMO are used in a somewhat stepwise manner for stabilisation. Delayed surgery has become established later in management plan. The impact of individual therapies (e.g. HFOV, iNO, ECMO) on outcome is difficult to ascertain. Little level 1 or 2 evidence exists. Randomised studies and reviews on the role of ECMO have not yet proven any long-term survival benefit. One pilot randomised study of thoracoscopic repair suggests increased acidosis; intraoperative blood gases and CO2 levels should be closely monitored. Monitoring tissue oxygenation should be considered. There is no evidence to suggest the best patch material.

Factors Associated with Survival during High-Frequency Oscillatory Ventilation in Children

Our aim is to determine indicators of survival in children with severe hypoxic respiratory failure (HRF) after transition to high-frequency oscillatory ventilation (HFOV). Single-center retrospective examination of children with HRF transitioned to HFOV. Blood gases and ventilator settings 24 hours prior to and 48 hours after HFOV in survivors and nonsurvivors were evaluated. Sixty-two children with mean age of 7 years and mean weight of 26 kg were included with an observed mortality of 29%. Mean airway pressures (Paw), oxygenation index (OI), arterial oxygen partial pressure (PaO₂)/fraction of inspired oxygen (FiO₂) (P/F) ratio, pH, bicarbonate, and arterial carbon dioxide partial pressure were similar prior to HFOV in survivors and nonsurvivors. During HFOV, mean OI and P/F ratio improved in both groups with an average Paw increase of ∼10 cm H₂O. Survivors had lower OI than nonsurvivors (21 ± 0.9 vs. 26.5 ± 2.2; p < 0.01) beginning 24 hours after HFOV. P/F ratio appears to diverge by 36 hours, with survivors having P/F ratio >200. Survivors had higher pH than nonsurvivors at 36 hours (7.40 ± 0.01 vs. 7.32 ± 0.02; p < 0.05), higher bicarbonate levels (27.1 ± 0.7 vs. 23.9 ± 1.3 mEq/L), and similar arterial carbon dioxide partial pressure with less oscillatory support (i.e., hertz and amplitude). Inhaled nitric oxide was used in 53% of patients with improvements in oxygenation but with no effect on mortality. HFOV improves oxygenation in children with severe HRF. Nonsurvivors can be distinguished from survivors at 24 to 36 hours during HFOV by higher OI, metabolic acidosis, and higher oscillatory support. These data may assist in prognostication or timing of initiating alternative therapies, such as extracorporeal membrane oxygenation.

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.

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.

Respiratory support practices in infants born at term in the United Kingdom

Infants born at term requiring mechanical ventilation suffer significant mortality and morbidity, yet few studies have tried to identify the optimum respiratory support for such infants. We, therefore, hypothesised that practice would vary, particularly between different levels of neonatal care provision. The lead clinicians of all 212 UK neonatal units were asked to complete an electronic web-based survey regarding respiratory support practices for term-born infants. Survey questions included the level of neonatal care provided, number of term-born infants ventilated per annum, initial and rescue ventilation modes and whether surfactant or inhaled nitric oxide (NO) were used. The overall response rate was 82 %. A greater proportion of neonatal intensive care units (NICUs) compared to local neonatal units (LNUs) stated that they used volume-targeting, particularly for infants with RDS (p = 0.0006) or congenital pneumonia (p = 0.0005). High-frequency oscillatory ventilation was stated as initial mode by a greater proportion of NICUs compared to LNUs and special care units (SCUs), particularly for respiratory distress syndrome (p < 0.0001) or persistent pulmonary hypertension of the newborn (p < 0.001). Continuous mandatory ventilation was stated to be the rescue mode by a greater proportion of LNUs/SCUs compared to NICUs (p < 0.0001). Surfactant was stated to be most commonly given for respiratory distress syndrome (79 % of units) and MAS (61 % of units); surfactant use was lowest in SCUs (p < 0.0001); inhaled NO was infrequently used by LNUs and SCUs. Conclusions There was considerable variation in respiratory support practices for term-born infants, particularly between different levels of neonatal care provision.

High-frequency oscillatory ventilation and short-term outcome in neonates and infants undergoing cardiac surgery: a propensity score analysis

INTRODUCTION

Experience with high-frequency oscillatory ventilation (HFOV) after congenital cardiac surgery is limited despite evidence about reduction in pulmonary vascular resistance after the Fontan procedure. HFOV is recommended in adults and children with acute respiratory distress syndrome. The aim of the present study was to assess associations between commencement of HFOV on the day of surgery and length of mechanical ventilation, length of Intensive Care Unit (ICU) stay and mortality in neonates and infants with respiratory distress following cardiac surgery.

METHODS

A logistic regression model was used to develop a propensity score, which accounted for the probability of being switched from conventional mechanical ventilation (CMV) to HFOV on the day of surgery. It included baseline characteristics, type of procedure and postoperative variables, and was used to match each patient with HFOV with a control patient, in whom CMV was used exclusively. Length of mechanical ventilation, ICU stay and mortality rates were compared in the matched set.

RESULTS

Overall, 3,549 neonates and infants underwent cardiac surgery from January 2001 through June 2010, 120 patients were switched to HFOV and matched with 120 controls. After adjustment for the delay to sternal closure, duration of renal replacement therapy, occurrence of pulmonary hypertension and year of surgery, the probability of successful weaning over time and the probability of ICU delivery over time were significantly higher in patients with HFOV, adjusted hazard ratios and 95% confidence intervals: 1.63, 1.17 to 2.26 (P = 0.004). and 1.65, 95% confidence intervals: 1.20 to 2.28 (P = 0.002) respectively. No association was found with mortality.

CONCLUSIONS

When commenced on the day of surgery in neonates and infants with respiratory distress following cardiac surgery, HFOV was associated with shorter lengths of mechanical ventilation and ICU stay than CMV.

Neonatal ventilatory techniques - which are best for infants born at term?

Few studies have examined ventilatory modes exclusively in infants born at term. Synchronous intermittent mandatory ventilation (SIMV) compared to intermittent mandatory ventilation (IMV) is associated with a shorter duration of ventilation. The limited data on pressure support, volume targeted ventilation and neurally adjusted ventilatory assist demonstrate only short term benefits in term born infants. Favourable results of high-frequency oscillatory ventilation (HFOV) in infants with severe respiratory failure were not confirmed in the two randomised trials. Nitric oxide (NO) in term born infants, except in those with congenital diaphragmatic hernia (CDH), reduces the combined outcome of death and requirement for extracorporeal membrane oxygenation (ECMO). In infants with severe refractory hypoxaemic respiratory failure, ECMO, except in infants with CDH, reduced mortality and the combined outcome of death and severe disability at long-term follow-up. Randomised studies with long term outcomes are required to determine the optimum modes of ventilation in term born infants.

Noninvasive high frequency oscillatory ventilation through nasal prongs: bench evaluation of efficacy and mechanics

BACKGROUND

Noninvasive high frequency oscillatory ventilation through nasal prongs (nHFOV) has been proposed as a new respiratory support in neonatology. We studied the effect of ventilation parameters and nasal prongs on nHFOV efficacy and mechanics.

METHODS

Customized sealed circuits connecting a SM3100A oscillator to a neonatal lung model were developed to evaluate the effect of applying HFOV via two different sized nasal prongs on delivered tidal volume and pressure. Measurements were made across a range of frequencies and pressures; amplitude was set to obtain visible lung oscillation.

RESULTS

Volume delivered by peak-to-peak oscillation, ventilation, and pressure significantly differed among the interfaces, being higher for large cannulae and the control circuit (p < 0.0001). The interposition of a large or small nasal prong reduced volume to 56 and 26%, ventilation to 32 and 9%, and mean pressure to 83 and 79%, respectively, of the values measured for the direct connection of the oscillator to the test lung. Volume and ventilation were inversely related to frequency, which was particularly evident with larger diameter circuits due to higher delivered tidal volume (R (2) > 0.9). Increasing ventilation was associated with larger tidal volume and nasal prong diameter (adjusted R (2) = 0.97).

CONCLUSIONS

nHFOV using common nasal prongs is technically possible. Efficiency of tidal volume delivery is significantly affected by prong diameter.

The design of future pediatric mechanical ventilation trials for acute lung injury

Pediatric practitioners face unique challenges when attempting to translate or adapt adult-derived evidence regarding ventilation practices for acute lung injury or acute respiratory distress syndrome into pediatric practice. Fortunately or unfortunately, there appears to be selective adoption of adult practices for pediatric mechanical ventilation, many of which pose considerable challenges or uncertainty when translated to pediatrics. These differences, combined with heterogeneous management strategies within pediatric critical care, can complicate clinical practice and make designing robust clinical trials in pediatric acute respiratory failure particularly difficult. These issues surround the lack of explicit ventilator protocols in pediatrics, either computer or paper based; differences in modes of conventional ventilation and perceived marked differences in the approach to high-frequency oscillatory ventilation; challenges with patient recruitment; the shortcomings of the definition of acute lung injury and acute respiratory distress syndrome; the more reliable yet still somewhat unpredictable relationship between lung injury severity and outcome; and the reliance on potentially biased surrogate outcome measures, such as ventilator-free days, for all pediatric trials. The purpose of this review is to highlight these challenges, discuss pertinent work that has begun to address them, and propose potential solutions or future investigations that may help facilitate comprehensive trials on pediatric mechanical ventilation and define clinical practice standards.