FIRST-line support for Assistance in Breathing in Children (FIRST-ABC): protocol for a multicentre randomised feasibility trial of non-invasive respiratory support in critically ill children

Seizure control via pH manipulation: a phase II double-blind randomised controlled trial of inhaled carbogen as adjunctive treatment of paediatric convulsive status epilepticus (Carbogen for Status Epilepticus in Children Trial (CRESCENT))

BACKGROUND

Paediatric convulsive status epilepticus is the most common neurological emergency presenting to emergency departments. Risks of resultant neurological morbidity and mortality increase with seizure duration. If the seizure fails to stop within defined time-windows, standard care follows an algorithm of stepwise escalation to more intensive treatments, ultimately resorting to induction of general anaesthesia and ventilation. Additionally, ventilatory support may also be required to treat respiratory depression, a common unwanted effect of treatment. There is strong pre-clinical evidence that pH (acid-base balance) is an important determinant of seizure commencement and cessation, with seizures tending to start under alkaline conditions and terminate under acidic conditions. These mechanisms may be particularly important in febrile status epilepticus: prolonged fever-related seizures which predominantly affect very young children. This trial will assess whether imposition of mild respiratory acidosis by manipulation of inhaled medical gas improves response rates to first-line medical treatment.

METHODS

A double-blind, placebo-controlled trial of pH manipulation as an adjunct to standard medical treatment of convulsive status epilepticus in children. The control arm receives standard medical management whilst inhaling 100% oxygen; the active arm receives standard medical management whilst inhaling a commercially available mixture of 95% oxygen, 5% carbon dioxide known as 'carbogen'. Due to the urgent need to treat the seizure, deferred consent is used. The primary outcome is success of first-line treatment in seizure cessation. Planned subgroup analyses will be undertaken for febrile and non-febrile seizures. Secondary outcomes include rates of induction of general anaesthesia, admission to intensive care, adverse events, and 30-day mortality.

DISCUSSION

If safe and effective 95% oxygen, 5% carbon dioxide may be an important adjunct in the management of convulsive status epilepticus with potential for pre-hospital use by paramedics, families, and school staff.

TRIAL REGISTRATION

EudraCT: 2021-005367-49. CTA: 17136/0300/001.

ISRCTN

52731862. Registered on July 2022.

High flow nasal cannula for respiratory support in term infants

BACKGROUND

Respiratory failure or respiratory distress in infants is the most common reason for non-elective admission to hospitals and neonatal intensive care units. Non-invasive methods of respiratory support have become the preferred mode of treating respiratory problems as they avoid some of the complications associated with intubation and mechanical ventilation. High flow nasal cannula (HFNC) therapy is increasingly being used as a method of non-invasive respiratory support. However, the evidence pertaining to its use in term infants (defined as infants ≥ 37 weeks gestational age to the end of the neonatal period (up to one month postnatal age)) is limited and there is no consensus of opinion regarding the safety and efficacy HFNC in this population.

OBJECTIVES

To assess the safety and efficacy of high flow nasal cannula oxygen therapy for respiratory support in term infants when compared with other forms of non-invasive respiratory support.

SEARCH METHODS

We searched the following databases in December 2022: Cochrane CENTRAL; PubMed; Embase; CINAHL; LILACS; Web of Science; Scopus. We also searched the reference lists of retrieved studies and performed a supplementary search of Google Scholar.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that investigated the use of high flow nasal cannula oxygen therapy in infants ≥ 37 weeks gestational age up to one month postnatal age (the end of the neonatal period).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility, performed data extraction, and assessed risk of bias in the included studies. Where studies were sufficiently similar, we performed a meta-analysis using mean differences (MD) for continuous data and risk ratios (RR) for dichotomous data, with their respective 95% confidence intervals (CIs). For statistically significant RRs, we calculated the number needed to treat for an additional beneficial outcome (NNTB). We used the GRADE approach to evaluate the certainty of the evidence for clinically important outcomes.

MAIN RESULTS

We included eight studies (654 participants) in this review. Six of these studies (625 participants) contributed data to our primary analyses. Four studies contributed to our comparison of high flow nasal cannula (HFNC) oxygen therapy versus continuous positive airway pressure (CPAP) for respiratory support in term infants. The outcome of death was reported in two studies (439 infants) but there were no events in either group. HFNC may have little to no effect on treatment failure, but the evidence is very uncertain (RR 0.98, 95% CI 0.47 to 2.04; 3 trials, 452 infants; very low-certainty evidence). The outcome of chronic lung disease (need for supplemental oxygen at 28 days of life) was reported in one study (375 participants) but there were no events in either group. HFNC may have little to no effect on the duration of respiratory support (any form of non-invasive respiratory support with or without supplemental oxygen), but the evidence is very uncertain (MD 0.17 days, 95% CI -0.28 to 0.61; 4 trials, 530 infants; very low-certainty evidence). HFNC likely results in little to no difference in the length of stay at the intensive care unit (ICU) (MD 0.90 days, 95% CI -0.31 to 2.12; 3 trials, 452 infants; moderate-certainty evidence). HFNC may reduce the incidence of nasal trauma (RR 0.16, 95% CI 0.04 to 0.66; 1 trial, 78 infants; very low-certainty evidence) and abdominal overdistension (RR 0.22, 95% CI 0.07 to 0.71; 1 trial, 78 infants; very low-certainty evidence), but the evidence is very uncertain. Two studies contributed to our analysis of HFNC versus low flow nasal cannula oxygen therapy (LFNC) (supplemental oxygen up to a maximum flow rate of 2 L/min). The outcome of death was reported in both studies (95 infants) but there were no events in either group. The evidence suggests that HFNC may reduce treatment failure slightly (RR 0.44, 95% CI 0.21 to 0.92; 2 trials, 95 infants; low-certainty evidence). Neither study reported results for the outcome of chronic lung disease (need for supplemental oxygen at 28 days of life). HFNC may have little to no effect on the duration of respiratory support (MD -0.07 days, 95% CI -0.83 to 0.69; 1 trial, 74 infants; very low-certainty evidence), length of stay at the ICU (MD 0.49 days, 95% CI -0.83 to 1.81; 1 trial, 74 infants; very low-certainty evidence), or hospital length of stay (MD -0.60 days, 95% CI -2.07 to 0.86; 2 trials, 95 infants; very low-certainty evidence), but the evidence is very uncertain. Adverse events was an outcome reported in both studies (95 infants) but there were no events in either group. The risk of bias across outcomes was generally low, although there were some concerns of bias. The certainty of evidence across outcomes ranged from moderate to very low, downgraded due to risk of bias, imprecision, indirectness, and inconsistency.

AUTHORS' CONCLUSIONS

When compared with CPAP, HFNC may result in little to no difference in treatment failure. HFNC may have little to no effect on the duration of respiratory support, but the evidence is very uncertain. HFNC likely results in little to no difference in the length of stay at the intensive care unit. HFNC may reduce the incidence of nasal trauma and abdominal overdistension, but the evidence is very uncertain. When compared with LFNC, HFNC may reduce treatment failure slightly. HFNC may have little to no effect on the duration of respiratory support, length of stay at the ICU, or hospital length of stay, but the evidence is very uncertain. There is insufficient evidence to enable the formulation of evidence-based guidelines on the use of HFNC for respiratory support in term infants. Larger, methodologically robust trials are required to further evaluate the possible health benefits or harms of HFNC in this patient population.

Variation in Practice Related to the Use of High Flow Nasal Cannula in Critically Ill Children

OBJECTIVES

To determine current management of critically ill children and gather views regarding high flow nasal cannula therapy and to evaluate research priorities for a large prospective randomized controlled trial of noninvasive respiratory support in children.

DESIGN

Multinational cross-sectional questionnaire survey conducted in 2018.

SETTING

The sample included pediatric intensive care physicians in North and South America, Asia, Europe, and Australia/New Zealand.

MEASUREMENT

Questions consisted of: 1) characteristics of intensivists and hospital, 2) practice of high flow nasal cannula, 3) supportive treatment, and 4) research of high flow nasal cannula.

INTERVENTIONS

None.

MAIN RESULTS

We collected data from 1,031 respondents; 919 (North America, 215; Australia/New Zealand, 34; Asia, 203; South America, 186; Europe, 281) were analyzed. Sixty-nine percent of the respondents used high flow nasal cannula in non-PICU settings in their institutions. For a case of bronchiolitis/pneumonia infant, 2 L/kg/min of initial flow rate was the most commonly used. For a scenario of pneumonia with 30 kg weight, more than 60% of the respondents initiated flow based on patient body weight; while, 18% applied a fixed flow rate. Noninvasive ventilation was considered as a next step in more than 85% of respondents when the patient is failing with high flow nasal cannula. Significant practice variations were observed in clinical practice markers used, flow weaning strategy, and supportive practices. Views comparing high flow nasal cannula to continuous positive airway pressure also noticeably varied across the respondents.

CONCLUSIONS

Significant practice variations including views of high flow nasal cannula compared to continuous positive airway pressure was found among pediatric intensive care physicians. To expedite establishment and standardization of high flow nasal cannula practice, research aimed at understanding the heterogeneity found in this study should be undertaken.

Predicting use of high-flow nasal cannula therapy following extubation in paediatrics

BACKGROUND

High-flow nasal cannula (HFNC) therapy is widely used for respiratory support within paediatrics, most commonly used as a supportive measure in acute respiratory failure, aiming to avoid invasive mechanical ventilation (IMV). It is increasingly being used following extubation of critically ill children potentially at a higher risk of requiring re-intubation. Less data indicate the use for post-extubation HFNC therapy or possible clinical outcomes of this therapy.

AIMS AND OBJECTIVES

To identify reasons for, and variables to predict, the use of HFNC therapy post-extubation.

DESIGN

This was a retrospective case-control study.

METHODS

All children admitted to a nine-bedded regional paediatric intensive care unit requiring IMV between 18 December 2017 and 28 November 2018 were identified. The demographic data and bedside clinical and laboratory variables of the patients requiring HFNC therapy were compared with those who did not require HFNC.

RESULTS

There was no statistical difference in the median age and weight of children receiving HFNC therapy post-extubation compared with children not receiving it. In a logistic regression model, the highest ventilation (peak inspiratory pressure) and oxygen requirements in the first 24 hours of admission, along with the presence of comorbidity and use of HFNC therapy prior to intubation, predicted the use of HFNC following extubation, (r² 0.42, area under the receiver operating curve 0.843, P < .0001).

CONCLUSIONS

The direct correlation between high initial ventilatory requirements and pre-existing comorbidity was significant for the use of post-extubation HFNC therapy. This may be useful to stratify children in the use of HFNC therapy post-extubation in the critically ill population.

RELEVANCE TO CLINICAL PRACTICE

This study provides evidence that it may be possible to predict the use of HFNC therapy post-extubation. Avoiding unnecessary use of this therapy improves patient care while providing a positive economic impact.

Patterns of Use of Heated Humidified High-Flow Nasal Cannula Therapy in PICUs in the United Kingdom and Republic of Ireland

OBJECTIVES

To 1) describe patterns of use of high-flow nasal cannula therapy, 2) examine differences between patients started on high-flow nasal cannula and those started on noninvasive ventilation, and 3) explore whether patients who failed high-flow nasal cannula therapy were different from those who did not.

DESIGN

Retrospective analysis of data collected prospectively by the Paediatric Intensive Care Audit Network.

SETTING

All PICUs in the United Kingdom and Republic of Ireland (n = 34).

PATIENTS

Admissions to study PICUs (2015-2016) receiving any form of respiratory support at any time during PICU stay.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Eligible admissions were classified into nine groups based on the combination of the first-line and second-line respiratory support modes. Uni- and multivariate analyses were performed to test the association between PICU and patient characteristics and two outcomes: 1) use of high-flow nasal cannula versus noninvasive ventilation as first-line mode and 2) high-flow nasal cannula failure, requiring escalation to noninvasive ventilation and/or invasive ventilation. We analyzed data from 26,423 admissions; high-flow nasal cannula was used in 5,951 (22.5%) at some point during the PICU stay. High-flow nasal cannula was used for first-line support in 2,080 (7.9%) and postextubation support in 978 admissions (4.5% of patients extubated after first-line invasive ventilation). High-flow nasal cannula failure occurred in 559 of 2,080 admissions (26.9%) when used for first-line support. Uni- and multivariate analyses showed that PICU characteristics as well as patient age, primary diagnostic group, and admission type had a significant influence on the choice of first-line mode (high-flow nasal cannula or noninvasive ventilation). Younger age, unplanned admission, and higher admission severity of illness were independent predictors of high-flow nasal cannula failure.

CONCLUSIONS

The use of high-flow nasal cannula is common in PICUs in the United Kingdom and Republic of Ireland. Variation in the choice of first-line respiratory support mode (high-flow nasal cannula or noninvasive ventilation) between PICUs reflects the need for clinical trial evidence to guide future practice.

High flow nasal cannula in the emergency department: indications, safety and effectiveness

INTRODUCTION

Heated humidified high flow nasal cannula therapy (HHHFNCT) is emerging as a popular non-invasive mode of respiratory support in adults and children. In recent years, its use has extended beyond the intensive care unit to other clinical areas. This review aims to explore the mechanism of action, indications, safety, and effectiveness of HHHFNCT use in the Emergency Department (ED).

AREAS COVERED

The mechanism of action of HHHFNCT, as well as its use in adult and pediatric ED will be discussed in this review.

EXPERT COMMENTARY

While there exists increasing enthusiasm in the use of HHHFNCT in the ED, constant monitoring of the patients and an experienced assessment of their response to treatment are critical and may require additional manpower deployment, which may be challenging, in the busy ED environment. Our experience with the use of HHHFNCT in children is still growing. Continual research in this area remains crucial in helping us better understand the patient types and conditions managed in ED that would most benefit from this device.

Randomized Study of Early Continuous Positive Airways Pressure in Acute Respiratory Failure in Children With Impaired Immunity (SCARF) ISRCTN82853500

OBJECTIVES

Previous trials in adults with impaired immunity and respiratory failure suggest that early noninvasive ventilation avoids endotracheal intubation and improves survival. No randomized clinical trials have addressed this question in children.

DESIGN

We undertook an open, parallel-group randomized trial in three pediatric hospitals.

SUBJECTS

Children with impaired immunity and acute respiratory failure defined as tachypnoea (> 90th centile); a new requirement for supplemental oxygen; and new chest radiograph infiltrates.

INTERVENTIONS

Children were randomly assigned to early PICU admission for continuous positive airways pressure (early continuous positive airways pressure) or to standard care. The primary outcome was endotracheal intubation by 30 days.

MEASUREMENTS AND MAIN RESULTS

One-hundred fourteen children met inclusion criteria of whom 42 were randomized between January 2013 and January 2016. There was no significant difference in endotracheal intubation by 30 days with early continuous positive airways pressure (10/21; 48%) compared with standard care (5/21; 24%), odds ratio 2.9 (0.8-10.9), p value equals to 0.11. However, 30-day mortality was significantly higher with early continuous positive airways pressure (7/21; 33%) compared with standard care (1/21; 5%), odds ratio 10.0 (1.1-90.6), p value equals to 0.041. Mortality at 90 days was early continuous positive airways pressure (11/21; 52%) versus standard care (4/21; 19%), odds ratio 4.7 (1.2-18.6), p value equals to 0.029, whereas mortality at 1 year was similar early continuous positive airways pressure (13/21; 61.9%) versus standard care (9/21; 42.7%), odds ratio 2.2 (0.6-7.4), p value equals to 0.22. There were two serious adverse events: early continuous positive airways pressure (pneumothorax) and standard care (hemothorax).

CONCLUSIONS

This study provided no evidence to support early PICU admission for continuous positive airways pressure in children with acute respiratory failure and impaired immunity. There was a trend toward increased endotracheal intubation and a higher early mortality in the early continuous positive airways pressure group.

FIRST-line support for Assistance in Breathing in Children (FIRST-ABC): a multicentre pilot randomised controlled trial of high-flow nasal cannula therapy versus continuous positive airway pressure in paediatric critical care

BACKGROUND

Although high-flow nasal cannula therapy (HFNC) has become a popular mode of non-invasive respiratory support (NRS) in critically ill children, there are no randomised controlled trials (RCTs) comparing it with continuous positive airway pressure (CPAP). We performed a pilot RCT to explore the feasibility, and inform the design and conduct, of a future large pragmatic RCT comparing HFNC and CPAP in paediatric critical care.

METHODS

In this multi-centre pilot RCT, eligible patients were recruited to either Group A (step-up NRS) or Group B (step-down NRS). Participants were randomised (1:1) using sealed opaque envelopes to either CPAP or HFNC as their first-line mode of NRS. Consent was sought after randomisation in emergency situations. The primary study outcomes were related to feasibility (number of eligible patients in each group, proportion of eligible patients randomised, consent rate, and measures of adherence to study algorithms). Data were collected on safety and a range of patient outcomes in order to inform the choice of a primary outcome measure for the future RCT.

RESULTS

Overall, 121/254 eligible patients (47.6%) were randomised (Group A 60%, Group B 44.2%) over a 10-month period (recruitment rate for Group A, 1 patient/site/month; Group B, 2.8 patients/site/month). In Group A, consent was obtained in 29/33 parents/guardians approached (87.9%), while in Group B 84/118 consented (71.2%). Intention-to-treat analysis included 113 patients (HFNC 59, CPAP 54). Most reported adverse events were mild/moderate (HFNC 8/59, CPAP 9/54). More patients switched treatment from HFNC to CPAP (Group A: 7/16, 44%; Group B: 9/43, 21%) than from CPAP to HFNC (Group A: 3/13, 23%; Group B: 5/41, 12%). Intubation occurred within 72 h in 15/59 (25.4%) of HFNC patients and 10/54 (18.5%) of CPAP patients (p = 0.38). HFNC patients experienced fewer ventilator-free days at day 28 (Group A: 19.6 vs. 23.5; Group B: 21.8 vs. 22.2).

CONCLUSIONS

Our pilot trial confirms that, following minor changes to consent procedures and treatment algorithms, it is feasible to conduct a large national RCT of non-invasive respiratory support in the paediatric critical care setting in both step-up and step-down NRS patients.

TRIAL REGISTRATION

clinicaltrials.gov, NCT02612415 . Registered on 23 November 2015.