Nasal High-Flow (NHF) Improves Ventilation in Patients with Interstitial Lung Disease (ILD)-A Physiological Study

INTRODUCTION

Acute hypercapnic respiratory failure has a poor prognosis in patients with interstitial lung disease (ILD). Recent data demonstrated a positive effect of nasal high-flow (NHF) in patients with acute hypoxemic respiratory failure. Preliminary data also show benefits in several hypercapnic chronic lung diseases.

OBJECTIVES

The aim of this study was to characterize flow-dependent changes in mean airway pressure, breathing volumes, and breathing frequency and decreases in PCO2.

METHODS

Mean airway pressure was measured in the nasopharyngeal space. To evaluate breathing volumes, a polysomnographic device was used (16 patients). All subjects received 20, 30, 40, and 50 L/min and-to illustrate the effects-nCPAP and nBiPAP. Capillary blood gas analyses were performed in 25 hypercapnic ILD subjects before and 5 h after the use of NHF. Additionally, comfort and dyspnea during the use of NHF were surveyed.

RESULTS

NHF resulted in a small flow-dependent increase in mean airway pressure. Tidal volume was unchanged and breathing rate decreased. The calculated minute volume decreased by 20 and 30 L/min NHF breathing. In spite of this fact, hypercapnia decreased at a flow rate of 24 L/min. Additionally, an improvement in dyspnea was observed.

CONCLUSIONS

NHF leads to a reduction in paCO2. This is most likely achieved by a washout of the respiratory tract and a reduction in functional dead space. NHF enhances the effectiveness of breathing in ILD patients by the reduction in respiratory rate. In summary, NHF works as an effective ventilatory support device in hypercapnic ILD patients.

Exhalation Spreading During Nasal High-Flow Therapy at Different Flow Rates

OBJECTIVES

Severe acute respiratory syndrome coronavirus 2 is transmitted through aerosols and droplets. Nasal high-flow therapy could possibly increase the spreading of exhalates from patients. The aim of this study is to investigate whether nasal high-flow therapy affects the range of the expiratory plume compared with spontaneous breathing.

DESIGN

Interventional experiment on single breaths of a healthy volunteer.

SETTING

Research laboratory at the Bauhaus-University Weimar.

SUBJECTS

A male subject.

INTERVENTIONS

Videos and images from a schlieren optical system were analyzed during spontaneous breathing and different nasal high-flow rates.

MEASUREMENTS AND MAIN RESULTS

The maximal exhalation spread was 0.99, 2.18, 2.92, and 4.1 m during spontaneous breathing, nasal high-flow of 20 L/min, nasal high-flow of 40 L/min, and nasal high-flow of 60 L/min, respectively. Spreading of the expiratory plume in the sagittal plane can completely be blocked with a surgical mask.

CONCLUSIONS

Nasal high-flow therapy increases the range of the expiratory air up to more than 4 meters. The risk to pick up infectious particles could be increased within this range. Attachment of a surgical mask over the nasal high-flow cannula blocks the expiratory airstream.

Closed-Loop Oxygen Control Using a Novel Nasal High-Flow Device: A Randomized Crossover Trial

BACKGROUND

Oxygen administration is recommended for patients with hypoxemia to achieve a target [Formula: see text] range. Strategies to achieve this in clinical practice are suboptimal. We investigated automatic oxygen titration using a novel nasal high-flow device with closed-loop oxygen control. The objective of this proof-of-concept study was to determine whether closed-loop control was able to respond to desaturation and subsequent recovery in a controlled laboratory-based environment.

METHODS

We conducted a single-blind randomized crossover trial in adults with chronic respiratory disease who had a resting [Formula: see text] ≥ 92% and desaturated to < 90% during a 6-min walk test (6MWT). Nasal high-flow was administered during a 6MWT and a subsequent 10-min rest period with either room air, a fixed concentration of 28% oxygen, or oxygen titrated automatically using closed-loop control.

RESULTS

The study involved 42 subjects. Closed-loop control maintained [Formula: see text] within the target range of 92-96% for a mean (SD) duration of 54.4 ± 30.1% of the 6MWT and 67.3 ± 26.8% of the recovery period. The proportion of time spent with an [Formula: see text] in the target range during the 6MWT was significantly greater for closed-loop control compared to room air, with a difference of 26.0% (95% CI 17.7-34.2, P < .001); this proportion of time was not significantly different compared to the fixed concentration of 28% oxygen, with a difference of -8.2% (95% CI -16.5 to 0.1, P = .052). The proportion of time spent in the target range during the rest period was significantly greater compared to 28% oxygen, with a difference of 19.3% (95% CI 8.9-29.7, P < .001); this proportion of time was not significantly different compared to room air, with a difference of -9.3% (95% CI -19.7 to 1.0, P = .08).

CONCLUSIONS

This study provides proof-of-concept evidence that the novel nasal high-flow device with closed-loop control can respond to changes in [Formula: see text] outside a target saturation range using a model of exercise-induced desaturation and subsequent recovery.

Nasal high-flow versus noninvasive ventilation in patients with chronic hypercapnic COPD

Background

Despite the encouraging results of noninvasive ventilation (NIV) in chronic hypercapnic COPD patients, it is also evident that some patients do not tolerate NIV or do not benefit from it. We conducted a study in which COPD patients with stable, chronic hypercapnia were treated with NIV and nasal high-flow (NHF) to compare effectiveness.

Methods

In a multi-centered, randomized, controlled, cross-over design, patients received 6 weeks of NHF ventilation followed by 6 weeks of NIV ventilation or vice-versa (TIBICO) between 2011 and 2016. COPD patients with stable daytime hypercapnia (pCO₂≥50 mmHg) were recruited from 13 German centers. The primary endpoint was pCO₂ changes from baseline blood gas, lung function, quality of life (QoL), the 6 min walking test, and duration of device use were secondary endpoints.

Results

A total of 102 patients (mean±SD) age 65.3±9.3 years, 61% females, body mass index 23.1±4.8 kg/m², 90% GOLD D, pCO₂ 56.5±5.4 mmHg were randomized. PCO₂ levels decreased by 4.7% (n=94; full analysis set; 95% CI 1.8-7.5, P=0.002) using NHF and 7.1% (95% CI 4.1-10.1, P<0.001) from baseline using NIV (indistinguishable to intention-to-treat analysis). The difference of pCO₂ changes between the two devices was -1.4 mmHg (95% CI -3.1-0.4, P=0.12). Both devices had positive impact on blood gases and respiratory scores (St. George's Respiratory Questionnaire, Severe Respiratory Insufficiency Questionnaire).

Conclusions

NHF may constitute an alternative to NIV in COPD patients with stable chronic hypercapnia, eg, those not tolerating or rejecting NIV with respect to pCO₂ reduction and improvement in QoL.

Transnasal Humidified Rapid Insufflation Ventilatory Exchange in children requiring emergent intubation (Kids THRIVE): a protocol for a randomised controlled trial

INTRODUCTION

Emergency intubation of children with abnormal respiratory or cardiac physiology is a high-risk procedure and associated with a high incidence of adverse events including hypoxemia. Successful emergency intubation is dependent on inter-related patient and operator factors. Preoxygenation has been used to maximise oxygen reserves in the patient and to prolong the safe apnoeic time during the intubation phase. Transnasal Humidified Rapid Insufflation Ventilatory Exchange (THRIVE) prolongs the safe apnoeic window for a safe intubation during elective intubation. We designed a clinical trial to test the hypothesis that THRIVE reduces the frequency of adverse and hypoxemic events during emergency intubation in children and to test the hypothesis that this treatment is cost-effective compared with standard care.

METHODS AND ANALYSIS

The Kids THRIVE trial is a multicentre randomised controlled trial performed in participating emergency departments and paediatric intensive care units. 960 infants and children aged 0-16 years requiring emergency intubation for all reasons will be enrolled and allocated to THRIVE or control in a 1:1 allocation with stratification by site, age (<1, 1-7 and >7 years) and operator (junior and senior). Children allocated to THRIVE will receive weight appropriate transnasal flow rates with 100% oxygen, whereas children in the control arm will not receive any transnasal oxygen insufflation. The primary outcomes are defined as follows: (1) hypoxemic event during the intubation phase defined as SpO₂ <90% (patient-dependent variable) and (2) first intubation attempt success without hypoxemia (operator-dependent variable). Analyses will be conducted on an intention-to-treat basis.

ETHICS AND DISSEMINATION

Ethics approval for the protocol and consent process has been obtained (HREC/16/QRCH/81). The trial has been actively recruiting since May 2017. The study findings will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ACTRN12617000147381.