Abstract
BackgroundNon-invasive ventilation (NIV) improves survival and quality of life in amyotrophic lateral sclerosis (ALS) patients. The timing of referral to a home ventilation service (HVS), which is in part based on respiratory function tests, has shown room for improvement. It is currently unknown which respiratory function test predicts an appropriate timing of the initiation of NIV.MethodsWe analysed, retrospectively, serial data of five respiratory function tests: forced vital capacity (FVC), peak cough flow (PCF), maximum inspiratory and expiratory pressure (MIP and MEP) and sniff nasal inspiratory pressure (SNIP) in patients with ALS. Patients who had had at least one assessment of respiratory function and one visit at the HVS, were included. Our aim was to detect the test with the highest predictive value for the need for elective NIV in the following 3 months. We analysed time curves, currently used cut-off values for referral, and respiratory function test results between ‘NIV indication’ and ‘no-NIV indication’ patients.ResultsOne hundred ten patients with ALS were included of whom 87 received an NIV indication; 11.5% had one assessment before receiving an NIV indication, 88.5% had two or more assessments. The NIV indication was based on complaints of hypoventilation and/or proven (nocturnal) hypercapnia. The five respiratory function tests showed a descending trend during disease progression, where SNIP showed the greatest decline within the latest 3 months before NIV indication (mean = −22%). PCF at the time of referral to the HVS significantly discriminated between the groups ‘NIV-indication’ and ‘no NIV-indication yet’ patients at the first HVS visit: 259 (±92) vs. 348 (±137) L/min, p = 0.019. PCF and SNIP showed the best predictive characteristics in terms of sensitivity.ConclusionSNIP showed the greatest decline prior to NIV indication and PCF significantly differentiated ‘NIV-indication’ from ‘no NIV-indication yet’ patients with ALS. Currently used cut-off values might be adjusted and other respiratory function tests such as SNIP and PCF may become part of routine care in patients with ALS in order to avoid non-timely initiation of (non-invasive) ventilation.
Highlights
Non-invasive ventilation (NIV) improves survival and quality of life in amyotrophic lateral sclerosis (ALS) patients
A recent study in the Netherlands showed that 37% of the patients with ALS, at their first visit at a home ventilation service (HVS), already had a level of respiratory impairment that lead to an outright NIV indication, either elective (
Two or more respiratory functions tests (FVC, peak cough flow (PCF), Maximum Inspiratory Pressure (MIP), Maximum Expiratory Pressure (MEP) or sniff nasal inspiratory pressure (SNIP)) had to be assessed at least at the Radboudumc or HVS and at least one daytime capillary blood gas sample had to be taken at the HVS
Summary
Non-invasive ventilation (NIV) improves survival and quality of life in amyotrophic lateral sclerosis (ALS) patients. The timing of referral to a home ventilation service (HVS), which is in part based on respiratory function tests, has shown room for improvement. It is currently unknown which respiratory function test predicts an appropriate timing of the initiation of NIV. The initiation of NIV is partly based on complaints of nocturnal hypoventilation, such as morning headache, daytime sleepiness and loss of concentration or memory These complaints are not specific and may even be absent, which may lead clinicians to rely, in addition, on daytime tests of respiratory muscle function or pulmonary function [3]. A recent study in the Netherlands showed that 37% of the patients with ALS, at their first visit at a home ventilation service (HVS), already had a level of respiratory impairment that lead to an outright NIV indication, either elective (
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