Humidity and Inspired Oxygen Concentration During High-Flow Nasal Cannula Therapy in Neonatal and Infant Lung Models

Guidelines for high-flow nasal cannula oxygen therapy in neonates (2022)

High-flow nasal cannula (HFNC) oxygen therapy, which is important in noninvasive respiratory support, is increasingly being used in critically ill neonates with respiratory failure because it is comfortable, easy to setup, and has a low incidence of nasal trauma. The advantages, indications, and risks of HFNC have been the focus of research in recent years, resulting in the development of the application. Based on current evidence, we developed guidelines for HFNC in neonates using the Grading of Recommendations Assessment, Development and Evaluation (GRADE). The guidelines were formulated after extensive consultations with neonatologists, respiratory therapists, nurse specialists, and evidence-based medicine experts. We have proposed 24 recommendations for 9 key questions. The guidelines aim to be a source of evidence and reference of HFNC oxygen therapy in clinical practice, and so that more neonates and their families will benefit from HFNC.

Comparison of actual performance in humidification among different high-flow nasal cannula devices: a bench study

Background

The physiological effects of HFNC devices are closely related to temperature and humidity. HFNC devices from different manufacturers may have varied performances. It is unclear whether there are differences in the humidification performance of different HFNC devices and the degree of differences.

Methods

Four integrated HFNC devices (AIRVO 2, Fisher & Paykel Healthcare, Auckland, New Zealand; TNI softFlow 50, TNI Medical AG, Würzburg, Germany; HUMID-BH, RESPIRACARE, Shenyang, China; OH-70C, Micomme, Hunan, China) and a ventilator with an HFNC module (bellavista 1000, Imtmedical, Buchs, Switzerland) were evaluated using their matching circuits. The dew point temperature was set at 31, 34, and 37°C (set-DP). In MR850, it was set to non-invasive mode (34°C/-3°C) and invasive mode (40°C/-3°C), respectively. At each level of set-DP, the flow was set from 20 L/min up to its maximum set limit at a gradient of 5 L/min or 10 L/min. After stabilization, the dew point temperature, temperature, relative humidity, and flow rate of the delivered gas from the cannulas were recorded.

Results

There were significant differences in actual-DP among these devices at any set-DP (p < 0.001). The actual-DP of OH-70C and TNI softFlow 50 was lower than set-DP, and the difference between the actual-DP and the set-DP of these two devices increased with the increase of set-DP. AIRVO 2, bellavista 1000 (MR850), and HUMID-BH can provide the nominal humidity at 37°C. The actual-DP increased with the increase of set-flow under each set-DP in AIRVO 2, TNI softFlow 50 and bellavista 1000 (MR850), but decreased when the set-flow was greater than 60 L/min. The actual-T of the delivered gas was higher than actual-DP in all devices and was higher than set-DP in AIRVO 2 and HUMID-BH.

Conclusion

Set-flow, set-DP, and types of devices will affect the actual temperature and humidity of the delivered gas. AIRVO 2, bellavista 1000 (MR850), and HUMID-BH can provide the nominal humidity at 37°C and may be more suitable for tracheotomy patients. The flow rate over 60 L/min should be set with caution.

Humidified versus nonhumidified low-flow oxygen therapy in children with Pierre-Robin syndrome: A randomized controlled trial

BACKGROUND

Humidification is an important process in clinical oxygen therapy. We aimed to evaluate the effects and safety of humidified versus nonhumidified low-flow oxygen therapy in children with Pierre-Robin syndrome.

METHODS

This study was an open-label, single-centered randomized controlled trial (RCT) with a parallel group design. The study protocol has been registered in Chinese Clinical Trial Registry (ChiCTR1900021584). The children were randomized to the humidified versus nonhumidified groups. Average arterial oxygen partial pressure (PaO2) and carbon dioxide partial pressure (PaCO2), incidence of ventilator-associated pneumonia (VAP), nasal cavity dryness, nasal mucosal bleeding and bacterial contamination of the humidified bottle, the cost of nasal oxygen therapy and duration of intensive care unit (ICU) stay were analyzed.

RESULTS

A total of 213 children with Pierre-Robin syndrome were included. There were no significant differences in the gender, age, weight, prematurity, duration of anesthesia and surgery duration of mandibular traction between humidified group and nonhumidified group (all P > .05). No significant differences in the average arterial PaO2 and PaCO2 level on the postoperative day 1, 2, and ICU discharge between humidified group and nonhumidified group were found (all P > .05). There were no significant differences in the incidence of nasal cavity dryness, nasal mucosal bleeding, bacterial contamination and VAP, the duration of ICU stay between humidified group and nonhumidified group (all P > .05). The cost of nasal oxygen therapy in the humidified group was significantly less than that of nonhumidified group (P = .013).

CONCLUSIONS

Humidifying the oxygen with cold sterile water in the low-flow oxygen therapy in children may be not necessary. Future RCTs with lager sample size and rigorous design are warranted to further elucidate the effects and safety of humidified versus nonhumidified low-flow oxygen therapy.

The Association Between Very Premature Infant Body Temperatures Over Time and Respiratory Care

BACKGROUND

Due to global immaturity, very low birthweight (VLBW) infants (<1,500 g) require auxiliary thermal and respiratory care. However, the impact of respiratory care on infant thermal stability remains unclear.

AIMS

Examine the association between VLBW infant body temperatures over time and respiratory support type (mechanical ventilation (MV), continuous positive airway pressure (CPAP), room air (RA)), respiratory care interventions, and nursing care.

DESIGN

Exploratory, longitudinal, and correlational design.

SUBJECTS

12 infants <29 weeks' gestation (median = 27.1, 25.9-27.9) and <1,200 g (median = 865 g, 660-1,050 g).

MEASUREMENTS

Minute-to-minute body temperatures and continuous video data were collected over the first 5 days of life. Video data was coded with Noldus Observer®XT software. Respiratory support was retrieved from the electronic health record. Hierarchical multi-level, mixed-effects models for intensive longitudinal data examined the associations.

RESULTS

Body temperatures were associated with respiratory support type, respiratory care, and care events (all p < .0001). Pairwise comparison found significant differences in body temperatures between all respiratory support types (all p < .0001). The covariate-adjusted risk of hypothermia (<36.5 °C) was significantly greater during MV vs. RA (aOR = 2.6); CPAP vs. MV (aOR = 1.2); CPAP vs RA (aOR = 3.1); respiratory care vs. other types of care (aOR = 1.5); care event vs. closed portholes (aOR = 2.6).

CONCLUSION

Our results found an association between VLBW infant thermal instability and respiratory support type, respiratory care, and care events. Larger studies with advanced longitudinal analysis are needed to assess the causal impact of these interventions on infant temperatures over time, as well as the implications of longitudinal thermal instability on infant outcomes.

Comparison of Actual Performance in the Flow and Fraction of Inspired O2 among Different High-Flow Nasal Cannula Devices: A Bench Study

Background

High-flow nasal cannula (HFNC) oxygen therapy has been recommended for use in coronavirus disease 2019 (COVID-19) patients with acute respiratory failure and many other clinical conditions. HFNC devices produced by different manufacturers may have varied performance. Whether there is a difference in these devices and the extent of the differences in performance remain unknown.

Methods

Four HFNC devices (AIRVO 2, TNI softFlow 50, HUMID-BH, and OH-70C) and a ventilator with an HFNC module (bellavista 1000) were evaluated. The flow was set at 20, 25, 30, 35, 40, 45, 50, 60, 70, and 80 L/min, and the FiO₂ was set at 21%, 26%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, and 90%. Then, one side of the cannulas was clipped to simulate the compression, bending, or blocking of the nasal cannulas. The flow and FiO₂ of the delivered gas were recorded and compared among settings and devices.

Results

The actual-flow and actual-FiO₂ delivered by different settings and devices varied. AIRVO 2 had superior performance in flow and FiO₂ accuracy. bellavista 1000 and OH-70C had good performance in the accuracy of actual-flows and actual-FiO_2, respectively. bellavista 1000 and HUMID-BH had a larger flow range from 10 to 80 L/min, but only bellavista 1000 could provide a stable flow with an excessive resistance up to 60 L/min. TNI softFlow 50 had the best flow compensation and could provide sufficient flow with excessive resistance at 20–50 L/min.

Conclusions

The variation in flow, FiO₂ settings, and devices could influence the actual-flow and actual-FiO₂ delivered. AIRVO 2 and OH-70C showed better FiO₂ accuracy. TNI softFlow 50, bellavista 1000, and HUMID-BH could lower the risk of insufficient flow support due to accidental compression or blocking of the cannulas. In addition, ventilators with HFNC modules provided comparable flow and FiO₂ and could be an alternative to standalone HFNC devices.

A narrative review on trans-nasal pulmonary aerosol delivery

The use of trans-nasal pulmonary aerosol delivery via high-flow nasal cannula (HFNC) has expanded in recent years. However, various factors influencing aerosol delivery in this setting have not been precisely defined, and no consensus has emerged regarding the optimal techniques for aerosol delivery with HFNC. Based on a comprehensive literature search, we reviewed studies that assessed trans-nasal pulmonary aerosol delivery with HFNC by in vitro experiments, and in vivo, by radiolabeled, pharmacokinetic and pharmacodynamic studies. In these investigations, the type of nebulizer employed and its placement, carrier gas, the relationship between gas flow and patient’s inspiratory flow, aerosol delivery strategies (intermittent unit dose vs continuous administration by infusion pump), and open vs closed mouth breathing influenced aerosol delivery. The objective of this review was to provide rational recommendations for optimizing aerosol delivery with HFNC in various clinical settings.

Efficacy of High-Flow Nasal Cannula vs Standard Oxygen Therapy or Nasal Continuous Positive Airway Pressure in Children with Respiratory Distress: A Meta-Analysis

OBJECTIVES

To evaluate the efficacy of high-flow nasal cannula (HFNC) oxygen therapy in providing respiratory support of children with acute lower respiratory infection (ALRI), hypoxemia, and respiratory distress.

STUDY DESIGN

We performed a meta-analysis of randomized controlled trials that compared HFNC and standard flow oxygen therapy or nasal continuous positive airway pressure (nCPAP) and reported treatment failure as an outcome. Data were synthesized using Mann-Whitney U test.

RESULTS

Compared with standard oxygen therapy, HFNC significantly reduced treatment failure (risk ratio [RR] 0.49, 95% CI 0.40-0.60, P < .001) in children with mild hypoxemia (arterial pulse oximetry [SpO₂] >90% on room air). HFNC had an increased risk of treatment failure compared with nCPAP in infants age 1-6 months with severe hypoxemia (SpO₂ <90% on room air or SpO₂ >90% on supplemental oxygen) (RR 1.77, 95% CI 1.17-2.67, P = .007). No significant differences were found in intubation rates and mortality between HFNC and standard oxygen therapy or nCPAP. HFNC had a lower risk of nasal trauma compared with nCPAP (RR 0.35, 95% CI 0.16-0.77, P = .009).

CONCLUSIONS

Among children <5 years of age with ALRI, respiratory distress, and mild hypoxemia, HFNC reduced the risk of treatment failure when compared with standard oxygen therapy. However, nCPAP was associated with a lower risk of treatment failure than HFNC in infants age 1-6 months with ALRI, moderate-to-severe respiratory distress, and severe hypoxemia. No differences were found in intubation and mortality between HFNC and standard oxygen therapy or nCPAP.

Factors affecting FiO2 and PEEP during high-flow nasal cannula oxygen therapy: A bench study

INTRODUCTION

It is unknown if set-flow, peak inspiratory flow (PIF), tidal volume and set fraction of inspired O₂ (FiO₂ ) affect actual-FiO₂ and positive end-expiratory pressure (PEEP) during high-flow nasal cannula (HFNC) oxygen therapy. In addition, the extent of their influence is also unknown.

OBJECTIVES

To investigate the effects of set-FiO₂ , set-flow, PIF and tidal volume on the actual-FiO₂ and PEEP during HFNC oxygen therapy.

METHODS

A lung simulation model was used to study the factors that might affect FiO₂ and PEEP during HFNC therapy in vitro. These factors included set-flow (20, 40, 60, 80 and 120 L/min), PIF (40, 80 and 120 L/min), tidal volume (400 and 600 mL), and set-FiO₂ (30%, 50% and 70%). Actual-FiO₂ and PEEP were recorded for 10 consecutive breaths. Actual-FiO₂ and PEEP were compared under different conditions. Multivariate linear regressions were performed to investigate the effects of these factors on actual-FiO₂ and PEEP.

RESULTS AND CONCLUSION

Regression formula were: (a) actual-FiO₂ as the dependent variable: actual FiO₂  = 2.71 + 0.78 × set-FiO₂  + 0.17 × set-flow - 0.09 × PIF (F test, F = 3866.62, P < 0.001, R²  = 0.94), (b) PEEP as the dependent variable: PEEP = 1.35 + 0.15 × set-flow - 0.02 × PIF + 0.01 × tidal volume (F test, F = 4082.39, P < 0.001, R²  = 0.95). The following factors were found to affect actual-FiO₂ (in descending order): set-FiO₂ , set-flow and PIF. Tidal volume had little effect on actual-FiO₂ . Factors which affected PEEP were (in descending order): set-flow, peak inspiratory flow and tidal volume.

Temperature and Humidity Associated With Artificial Ventilation in the Premature Infant: An Integrative Review of the Literature

BACKGROUND

Approximately half of the 55,000 very low birth-weight infants (<1500 g) born in the United States each year develop bronchopulmonary dysplasia (BPD). Many etiologies have been associated with the development of BPD, including aberrant temperature/humidity levels of artificial ventilation.

PURPOSE

The purpose of this literature review is to explore what is known regarding inspired air temperature/humidity levels from artificial ventilation in very premature infants, focusing on what levels these infants actually receive, and what factors impact these levels.

METHODS/SEARCH STRATEGY

PubMed, CINAHL, Scopus, and Web of Science were searched. Of the 830 articles retrieved, 23 were synthesized for study purpose, sample/study design, and temperature/humidity findings.

FINDINGS/RESULTS

Heating and humidification practices studied in neonatal ventilation did not maintain recommended levels. In addition, human neonatal studies and noninvasive neonatal ventilation research were limited. Furthermore, ventilation settings, environmental temperatures, and mouth position (in noninvasive ventilation) were found to impact temperature/humidity levels.

IMPLICATIONS FOR PRACTICE

Environmental temperatures and ventilatory settings merit consideration during artificial ventilation. In addition, aberrant temperature/humidity levels may impact infant body temperature stability; thus, employing measures to ensure adequate thermoregulation while receiving artificial ventilation must be a priority.

IMPLICATIONS FOR RESEARCH

This review underscores the need for further research into current warming and humidification techniques for invasive and noninvasive neonatal ventilation. A focus on human studies and the impact of aberrant levels on infant body temperature are needed. Future research may provide management options for achieving and maintaining target temperature/humidity parameters, thus preventing the aberrant levels associated with BPD.

Simulation-based research to improve infant health outcomes: Using the infant simulator to prevent infant shaking

Simulation is a technique that creates a situation or environment to allow persons to experience a representation of a real event for the purpose of practice, learning, evaluation, testing, or to gain understanding of systems or human actions. We will first provide an introduction to simulation in healthcare and describe the two types of simulation-based research (SBR) in the pediatric population. We will then provide an overview of the use of SBR to improve health outcomes for infants in health care settings and to improve parent-child interactions using the infant simulator. Finally, we will discuss previous and future research using simulation to reduce morbidity and mortality from abusive head trauma, the most common cause of traumatic death in infancy.