Effect of a passive exhalation port on tracheostomy ventilation in amyotrophic lateral sclerosis patients: a randomized controlled trial

The clinical practice guideline for the management of amyotrophic lateral sclerosis in Japan-update 2023

Amyotrophic lateral sclerosis (ALS) is an adult-onset intractable motor neuron disease characterized by selective degeneration of cortical neurons in the frontotemporal lobe and motor neurons in the brainstem and spinal cord. Impairment of these neural networks causes progressive muscle atrophy and weakness that spreads throughout the body, resulting in life-threatening bulbar palsy and respiratory muscle paralysis. However, no therapeutic strategy has yet been established to halt ALS progression. Although evidence for clinical practice in ALS remains insufficient, novel research findings have steadily accumulated in recent years. To provide updated evidence-based or expert consensus recommendations for the diagnosis and management of ALS, the ALS Clinical Practice Guideline Development Committee, approved by the Japanese Society of Neurology, revised and published the Japanese clinical practice guidelines for the management of ALS in 2023. In this guideline, disease-modifying therapies that have accumulated evidence from randomized controlled trials were defined as "Clinical Questions," in which the level of evidence was determined by systematic reviews. In contrast, "Questions and Answers" were defined as issues of clinically important but insufficient evidence, according to reports of a small number of cases, observational studies, and expert opinions. Based on a literature search performed in February 2022, recommendations were reached by consensus, determined by an independent panel, reviewed by external reviewers, and submitted for public comments by Japanese Society of Neurology members before publication. In this article, we summarize the revised Japanese guidelines for ALS, highlighting the regional and cultural diversity of care processes and decision-making. The guidelines cover a broad range of essential topics such as etiology, diagnostic criteria, disease monitoring and treatments, management of symptoms, respiration, rehabilitation, nutrition, metabolism, patient instructions, and various types of care support. We believe that this summary will help improve the daily clinical practice for individuals living with ALS and their caregivers.

Non-invasive Ventilation: Effect of Vented and Non-vented Exhalation Systems on Inspiratory CO2 and O2 Concentrations, Ventilation, and Breathing Pattern

INTRODUCTION

To increase CO₂ elimination and to reduce work of breathing in hypercapnic patients, non-invasive ventilation (NIV) can be applied via mask either with non-vented CO₂ exhalation systems or with vented systems with leak port. The effect of the exhalation system on CO₂ rebreathing in the mask and total gas exchange remains widely unknown. Aim of this study was to compare the exhalation systems in terms of inspiratory O₂ and CO₂ concentrations, breathing patterns and gas exchange.

METHODS

We prospectively examined 10 healthy subjects and 10 hypercapnic patients with both exhalation systems. O₂ and CO₂ were measured in the nose, in the mask, and in the ventilation circuit, and respiratory rate, tidal volume, and transcutaneous capnometry (PtcCO₂) were recorded during the experiments.

RESULTS

Using the non-vented system, CO₂ concentrations in the mask were significantly higher in both subject groups, and PtcCO₂ values in the patient group increased up to 3.6 mmHg compared to the vented system (p = 0.011). O₂ concentrations increased with higher O₂ flow rates, but were significantly lower in the vented settings in both groups. No effect in breathing pattern could be demonstrated during the measurement time.

CONCLUSION

Using NIV, the chosen exhalation system influences CO₂ and O₂ concentrations under the mask, CO₂ rebreathing from the mask and could influence the effectiveness of the ventilation support with regards to hypercapnia treatment. To compensate for relevant hypoxia, the O₂ supplementation must be set up to a sufficient level under a vented system.