Sleep Deficiency, Sleep Apnea, and Chronic Lung Disease.

With sleep occupying up to one-third of every adult's life, addressing sleep is essential to overall health. Sleep disturbance and deficiency are common in patients with chronic lung diseases and associated with worse clinical outcomes and poor quality of life. A detailed history incorporating nocturnal respiratory symptoms, symptoms of obstructive sleep apnea (OSA) and restless legs syndrome, symptoms of anxiety and depression, and medications is the first step in identifying and addressing the multiple factors often contributing to sleep deficiency in chronic lung disease. Additional research is needed to better understand the relationship between sleep deficiency and the spectrum of chronic lung diseases.

The impact of laboratory data missingness on sepsis diagnosis timeliness.

Objective: To investigate the impact of missing laboratory measurements on sepsis diagnostic delays. Materials and Methods: In adult patients admitted to 2 University of California San Diego (UCSD) hospitals from January 1, 2021 to June 30, 2024, we evaluated the relative time of organ failure (T OF) and time of clinical suspicion of sepsis (T suspicion) in patients with sepsis according to the Centers for Medicare & Medicaid Services (CMS) definition. Results: Of the patients studied, 48.7% (n = 2017) in the emergency department (ED), 30.8% (n = 209) in the wards, and 14.4% (n = 167) in the intensive care unit (ICU) had T OF after T suspicion. Patients with T OF after T suspicion had significantly higher data missingness of 1 or more of the 5 laboratory components used to determine organ failure. The mean number of missing labs was 4.23 vs 2.83 in the ED, 4.04 vs 3.38 in the wards, and 3.98 vs 3.19 in the ICU. Discussion: Our study identified many sepsis patients with missing laboratory results vital for the identification of organ failure and the diagnosis of sepsis at or before the time of clinical suspicion of sepsis. Addressing data missingness via more timely laboratory assessment could precipitate an earlier recognition of organ failure and potentially earlier diagnosis of and treatment initiation for sepsis. Conclusions: More prompt laboratory assessment might improve the timeliness of sepsis recognition and treatment.

Sleep, Sleep Apnea, and Fatigue in People Living With HIV.

BACKGROUND: People living with HIV (PLWH) often report fatigue even when viral load is suppressed. Obstructive sleep apnea (OSA), which is often associated with fatigue, is common in PLWH, but whether OSA explains fatigue in this population is unknown. SETTING: Academic university-affiliated HIV and Sleep Medicine Clinics. METHODS: PLWH, aged 18-65 years, with a body mass index of 20-35 kg/m2 and viral suppression (RNA <200 copies per mL), were recruited to undergo daytime questionnaires, including the Functional Assessment of Chronic Illness Therapy Fatigue Scale and Epworth Sleepiness Scale, 7 days of actigraphy (to determine daily sleep duration and activity amplitude and rhythms), and an in-laboratory polysomnography to assess for the presence and severity of OSA. RESULTS: Of 120 subjects with evaluable data, 90 (75%) had OSA using the American Academy of Sleep Medicine 3% desaturation or arousal criteria, with an apnea-hypopnea index >5/h. There was no difference in Functional Assessment of Chronic Illness Therapy scores between those with and without OSA, although those with OSA did report more daytime sleepiness as measured using the Epworth Sleepiness Scale. In a multivariable model, predictors of fatigue included more variable daily sleep durations and decreased mean activity counts. Sleepiness was predicted by the presence of OSA. CONCLUSION: OSA was very common in our cohort of PLWH, with those with OSA reporting more sleepiness but not more fatigue. Variability in sleep duration was associated with increased fatigue. Further study is needed to determine if treatment of OSA, or an emphasis on sleep consistency and timing, improves symptoms of fatigue in PLWH.

Association between a Recalled Positive Airway Pressure (PAP) Device and Incident Cancer: A Population-Based Study.

BACKGROUND: The real-world consequences of a Philips/Respironics recall for positive airway pressure (PAP) devices distributed between 2009 and 2021 are unknown. METHODS: We conducted a retrospective population-based study using health administrative databases (Ontario, Canada) on all new adult PAP users identified through the provincial funding system, free of cancer at baseline, who initiated (claimed) PAP treatment between 2012 and 2018. Everyone was followed from the PAP claim date to the earliest of incident cancer diagnosis, death, or the end of the follow-up (March 2022). We used inverse probability of treatment weighting to balance baseline characteristics between individuals on recalled devices and those on devices from other manufacturers. Weighted hazard ratios of incident cancer were compared between groups. RESULTS: Of 231 692 individuals identified, 58 204 (25.1%) claimed recalled devices, and 173 488 (74.9%) from other manufacturers. A meaningful baseline difference between groups (standardised difference≥0.10) was noted only by location-relevant covariates; other variables were mostly equally distributed (standardised differences≤0.06). Over a median follow-up of 6.3 years (IQR: 4.9-8.0), 11 166 (4.8%) developed cancer: unadjusted rates per 10 000 Person-Year (95 CI%) of 78.8 (76.0-81.7) in the recall group versus74.0 (72.4-75.6) in others (p=0.0034). Propensity score weighting achieved excellent balance in baseline characteristics between groups (standardised differences≤0.07). On a weighted sample, there was no statistical difference in the hazard of incident cancer between groups: cause-specific hazard ratio (recalled versus others) of 0.97, 95% CI: 0.89-1.06. CONCLUSION: In our real-world population study, compared to other manufacturers and adjusting for confounders, recalled devices do not appear to be independently associated with developing cancer.

Long-term outcomes after treatment of delirium during critical illness with antipsychotics (MIND-USA): a randomised, placebo-controlled, phase 3 trial.

BACKGROUND: Delirium is common during critical illness and is associated with long-term cognitive impairment and disability. Antipsychotics are frequently used to treat delirium, but their effects on long-term outcomes are unknown. We aimed to investigate the effects of antipsychotic treatment of delirious, critically ill patients on long-term cognitive, functional, psychological, and quality-of-life outcomes. METHODS: This prespecified, long-term follow-up to the randomised, double-blind, placebo-controlled phase 3 MIND-USA Study was conducted in 16 hospitals throughout the USA. Adults (aged ≥18 years) who had been admitted to an intensive care unit with respiratory failure or septic or cardiogenic shock were eligible for inclusion in the study if they had delirium. Participants were randomly assigned-using a computer-generated, permuted-block randomisation scheme with stratification by trial site and age-in a 1:1:1 ratio to receive intravenous placebo, haloperidol, or ziprasidone for up to 14 days. Investigators and participants were masked to treatment group assignment. 3 months and 12 months after randomisation, we assessed survivors' cognitive, functional, psychological, quality-of-life, and employment outcomes using validated telephone-administered tests and questionnaires. This trial was registered with ClinicalTrials.gov, NCT01211522, and is complete. FINDINGS: Between Dec 7, 2011, and Aug 12, 2017, we screened 20 914 individuals, of whom 566 were eligible and consented or had consent provided to participate. Of these 566 patients, 184 were assigned to the placebo group, 192 to the haloperidol group, and 190 to the ziprasidone group. 1-year survival and follow-up rates were similar between groups. Cognitive impairment was common in all three treatment groups, with a third of survivors impaired at both 3-month and 12-month follow-up in all groups. More than half of the surveyed survivors in each group had cognitive or physical limitations (or both) that precluded employment at both 3-month and 12-month follow-up. At both 3 months and 12 months, neither haloperidol (adjusted odds ratio 1·22 [95% CI 0·73-2.04] at 3 months and 1·12 [0·60-2·11] at 12 months) nor ziprasidone (1·07 [0·59-1·96] at 3 months and 0·94 [0·62-1·44] at 12 months) significantly altered cognitive outcomes, as measured by the Telephone Interview for Cognitive Status T score, compared with placebo. We also found no evidence that functional, psychological, quality-of-life, or employment outcomes improved with haloperidol or ziprasidone compared with placebo. INTERPRETATION: In delirious, critically ill patients, neither haloperidol nor ziprasidone had a significant effect on cognitive, functional, psychological, or quality-of-life outcomes among survivors. Our findings, along with insufficient evidence of short-term benefit and frequent inappropriate continuation of antipsychotics at hospital discharge, indicate that antipsychotics should not be used routinely to treat delirium in critically ill adults. FUNDING: National Institutes of Health and the US Department of Veterans Affairs.

Performance of a commercial smart watch compared to polysomnography reference for overnight continuous oximetry measurement and sleep apnea evaluation.

STUDY OBJECTIVES: We evaluated the accuracy and precision of continuous overnight oxygen saturation (SpO2) measurement by a commercial wrist device (WD) incorporating high-grade sensors and investigated WD estimation of sleep-disordered breathing by quantifying overnight oxygen desaturation index compared to polysomnography (PSG) oxygen desaturation index and apnea-hypopnea index (AHI) with and without sleep questionnaire data to assess the WD's ability to detect obstructive sleep apnea and determine its severity. METHODS: Participants completed sleep questionnaires, had a WD (Samsung Galaxy Watch 4) placed on their wrist, and underwent attended, in-laboratory overnight PSG (Nihon Kohden) with a pulse oximetry probe secured either to a finger or an ear lobe. PSG data were scored by a single experienced registered PSG technologist. Statistical analysis included demographic characteristics, continuous SpO2 measurement WD vs PSG root-mean-square error with Bland-Altman plot and linear regression associations. Predictive models for PSG oxygen desaturation index and AHI severity were built using logistic regression with probability cutoffs determined via receiver operating curve characteristics. RESULTS: The 51 participants analyzed had a median age of 49 (range, 22-78) years; 66.7% were male, with median body mass index of 28.1 (range, 20.1-47.3) kg/m2 with a race/ethnicity distribution of 49.0% Caucasian, 25.5% Hispanic, 9.8% African American, 9.8% Asian, and 5.9% Middle Eastern. WD vs PSG continuous SpO2 measurement in percentage points demonstrated a bias of 0.91 (95% confidence interval, 0.38, 1.45), standard deviation of 2.37 (95% confidence interval, 2.36, 2.38), and root-mean-square error of 2.54 (95% confidence interval, 2.34, 2.73). WD area under the curve receiver operating curve characteristics for predicting PSG were 0.882 oxygen desaturation index > 15 events/h, 0.894 AHI > 30 events/h, 0.800 AHI > 15 events/h, and 0.803 AHI > 5 events/h. WD plus select sleep questionnaire areas under the curve for predicting PSG were 0.943 AHI > 30 events/h, 0.868 AHI > 15 events/h, and 0.863 AHI > 5 events/h. CONCLUSIONS: The WD conducted reliable overnight continuous SpO2 monitoring with root-mean-square error < 3% vs PSG. Predictive models of PSG AHI based on WD measurements alone, or plus sleep questionnaires, demonstrated excellent to outstanding discrimination for obstructive sleep apnea identification and severity. Longitudinal WD use should be evaluated promptly based on the WD's potential to improve accessibility and accuracy of obstructive sleep apnea testing, as well as support treatment follow-up. CITATION: Browne SH, Vaida F, Umlauf A, Kim J, DeYoung P, Owens RL. Performance of a commercial smart watch compared to polysomnography reference for overnight continuous oximetry measurement and sleep apnea evaluation. J Clin Sleep Med. 2024;20(9):1479-1488.

Effect of obesity on sleep apnea pathogenesis differs in women versus men: multiple mediation analyses in the retrospective SNOOzzzE cohort.

There are multiple mechanisms underlying obstructive sleep apnea (OSA) development. However, how classic OSA risk factors such as body mass index (BMI) and sex portend to OSA development has not been fully described. Thus we sought to evaluate how obesity leads to OSA and assess how these mechanisms differ between men and women. The San Diego Multi-Outcome OSA Endophenotype (SNOOzzzE) cohort includes 3,319 consecutive adults who underwent a clinical in-laboratory polysomnography at the University of California, San Diego, sleep clinic between January 2017 and December 2019. Using routine polysomnography signals, we determined OSA endotypes. We then performed mediation analyses stratified by sex to determine how BMI influenced the apnea-hypopnea index (AHI) using OSA pathophysiological traits as mediators, adjusting for age, race, and ethnicity. We included 2,146 patients of whom 919 (43%) were women and 1,227 (57%) were obese [body mass index (BMI) > 30 kg/m2]. BMI was significantly associated with AHI in both women and men. In men, the adjusted effect of BMI on AHI was partially mediated by a reduction in upper airway stiffness (ßstandardized = 0.124), a reduction in circulatory delay (ßstandardized = 0.063), and an increase in arousal threshold (ßstandardized = 0.029; Pboot-strapped,all < 0.05). In women, the adjusted effect of BMI on AHI was partially mediated by a reduction in upper airway stiffness (ßstandardized = 0.05) and circulatory delay (ßstandardized = 0.037; Pboot-strapped,all < 0.05). BMI-related OSA pathogenesis differs by sex. An increase in upper airway collapsibility is consistent with prior studies. A reduction in circulatory delay may lead to shorter and thus more events per hour (higher AHI), while the relationship between arousal threshold and OSA is likely complex.NEW & NOTEWORTHY Our data provide important insights into obesity-related obstructive sleep apnea (OSA) pathogenesis, thereby validating, and extending, prior research findings. This is the largest sample size study to examine the relationships between obesity and gender on OSA pathogenesis. The influence of obesity on sleep apnea severity is mediated by different mechanistic traits (endotypes).

Pathogenesis of sleep disordered breathing in the setting of opioid use: A multiple mediation analysis using physiology.

STUDY OBJECTIVES: Opioid medications are commonly used and are known to impact both breathing and sleep, and are linked with adverse health outcomes including death. Clinical data indicate that chronic opioid use causes central sleep apnea, and might also worsen obstructive sleep apnea. The mechanisms by which opioids influence sleep-disordered breathing pathogenesis are not established. METHODS: Patients who underwent clinically-indicated polysomnography confirming sleep-disordered breathing (SDB) (AHI≥5/hr) were included. Each patient using opioids was matched by sex, age, and BMI to three control individuals not using opioids. Physiology known to influence SDB pathogenesis were determined from validated polysomnography-based signal analysis. PSG and physiology paramters of interest were compared between opioid and control individuals, adjusted for covariates. Mediation analysis was used to evaluate the link between opioids, physiology, and polysomnographic metrics. RESULTS: 178 individuals using opioids were matched to 534 controls (median [IQR] age 59 [50,65] years, BMI 33 [29,41] kg/m2, 57% female, daily morphine equivalent 30 [20,80] mg). Compared with controls, opioids were associated with increased central apneas (2.8 vs 1.7 events/hr; p=0.001) and worsened hypoxemia (5 vs 3% sleep with SpO2<88%; p=0.013), with similar overall AHI. Use of opioids was associated with higher loop gain, a lower respiratory rate and higher respiratory rate variability. Higher loop gain and increased respiratory rate variability mediated the effect of opioids on central apnea, but did not mediate the effect on hypoxemia. CONCLUSIONS: Opioids have multi-level effects impacting SDB. Targeting these factors may help mitigate deleterious respiratory consequences of chronic opioid use.

Temporal Trends in Methamphetamine Use in Patients Admitted to the Hospital: A Retrospective Cohort Study.

OBJECTIVES: Although methamphetamine use is common, the scope of methamphetamine use and outcomes for patients admitted to the hospital is unclear. This study aims to identify the prevalence of methamphetamine use from January 2012 to January 2022, coingestions, hospital course, and readmission rate of admitted patients. METHODS: This was a retrospective cohort study conducted on patients admitted to our center with the following inclusions: age older than 18 years, positive/"pending confirm" value for methamphetamine on urine drug screen, and/or an International Classification of Diseases , Tenth Revision , code related to stimulant use disorder as an active issue. Urine drug screen data are reported as methamphetamine +/- and polysubstance (PS) +/-. Patient demographics, admission diagnosis, and hospital course were extracted. Statistical tests used included t tests and Mann-Whitney U tests. RESULTS: A total of 19,159 encounters were included, representing 12,057 unique patients. The median (interquartile range) age was 43 (33-54) years. Of all encounters, 35.3% were methamphetamine + and PS -, and 46.3% were methamphetamine + and PS +. Hospitalizations increased from 883 in 2012 to 2532 in 2021. The median (IQR) hospital stay was 48 (48-120) hours. Of all encounters, 16.8% included an intensive care unit (ICU) admission, and the median ICU stay was 42 (21-87) hours. A total of 2988 patients (24.7%) were readmitted within the study period, and 4988 (71.5%) returned within 1 year of the previous encounter. In context of all emergency department admissions from 2013 to 2022, 13.1% had a urine drug screen + for methamphetamine. CONCLUSIONS: Hospitalizations with recent methamphetamine use doubled at our institution from 2012 to 2022. In addition, 1 in 4 is readmitted (typically within 1 year), and a minority requires ICU care.

Objectively measured peri-vaccination sleep does not predict COVID-19 breakthrough infection.

Prior studies have shown that sleep duration peri-vaccination influences an individual's antibody response. However, whether peri-vaccination sleep affects real-world vaccine effectiveness is unknown. Here, we tested whether objectively measured sleep around COVID-19 vaccination affected breakthrough infection rates. DETECT is a study of digitally recruited participants who report COVID-19-related information, including vaccination and illness data. Objective sleep data are also recorded through activity trackers. We compared the impact of sleep duration, sleep efficiency, and frequency of awakenings on reported breakthrough infection after the 2nd vaccination and 1st COVID-19 booster. Logistic regression models were created to examine if sleep metrics predicted COVID-19 breakthrough infection independent of age and gender. Self-reported breakthrough COVID-19 infection following 2nd COVID-19 vaccination and 1st booster. 256 out of 5265 individuals reported a breakthrough infection after the 2nd vaccine, and 581 out of 2583 individuals reported a breakthrough after the 1st booster. There was no difference in sleep duration between those with and without breakthrough infection. Increased awakening frequency was associated with breakthrough infection after the 1st booster with 3.01 ± 0.65 awakenings/hour in the breakthrough group compared to 2.82 ± 0.65 awakenings/hour in those without breakthrough (P < 0.001). Cox proportional hazards modeling showed that age < 60 years (hazard ratio 2.15, P < 0.001) and frequency of awakenings (hazard ratio 1.17, P = 0.019) were associated with breakthrough infection after the 1st booster. Sleep duration was not associated with breakthrough infection after COVID vaccination. While increased awakening frequency during sleep was associated with breakthrough infection beyond traditional risk factors, the clinical implications of this finding are unclear.

Impact of a deep learning sepsis prediction model on quality of care and survival.

Sepsis remains a major cause of mortality and morbidity worldwide. Algorithms that assist with the early recognition of sepsis may improve outcomes, but relatively few studies have examined their impact on real-world patient outcomes. Our objective was to assess the impact of a deep-learning model (COMPOSER) for the early prediction of sepsis on patient outcomes. We completed a before-and-after quasi-experimental study at two distinct Emergency Departments (EDs) within the UC San Diego Health System. We included 6217 adult septic patients from 1/1/2021 through 4/30/2023. The exposure tested was a nurse-facing Best Practice Advisory (BPA) triggered by COMPOSER. In-hospital mortality, sepsis bundle compliance, 72-h change in sequential organ failure assessment (SOFA) score following sepsis onset, ICU-free days, and the number of ICU encounters were evaluated in the pre-intervention period (705 days) and the post-intervention period (145 days). The causal impact analysis was performed using a Bayesian structural time-series approach with confounder adjustments to assess the significance of the exposure at the 95% confidence level. The deployment of COMPOSER was significantly associated with a 1.9% absolute reduction (17% relative decrease) in in-hospital sepsis mortality (95% CI, 0.3%-3.5%), a 5.0% absolute increase (10% relative increase) in sepsis bundle compliance (95% CI, 2.4%-8.0%), and a 4% (95% CI, 1.1%-7.1%) reduction in 72-h SOFA change after sepsis onset in causal inference analysis. This study suggests that the deployment of COMPOSER for early prediction of sepsis was associated with a significant reduction in mortality and a significant increase in sepsis bundle compliance.

Upper airway imaging and function in obstructive sleep apnea in people with and without HIV.

Obstructive sleep apnea (OSA) is common in people living with human immunodeficiency virus (HIV) (PLWH), but the underlying mechanisms are unclear. With improved long-term survival among PLWH, aging and obesity are increasingly prevalent in this population. These are also strong risk factors for the development of obstructive sleep apnea. We used magnetic resonance imaging (MRI) to measure upper airway (UA) anatomy and tongue fat content in PLWH with OSA (PLWH + OSA, n = 9) and in age-, sex-, and body mass index (BMI)-matched OSA controls (OSA, n = 11). We also quantified change in UA dimension during tidal breathing (during wakefulness and natural sleep) at four anatomical levels from the hard palate to the epiglottis along with synchronous MRI-compatible electroencephalogram and nasal flow measurements. All participants underwent on a separate night a baseline polysomnogram to assess OSA severity and an additional overnight physiological sleep study to measure OSA traits. We found no difference between the PLWH + OSA and the OSA control group in UA volume [PLWH + OSA: 12.8 mL (10.1-17.0), OSA: 14.0 mL (13.3-17.9), median (IQR)] or tongue volume [PLWH + OSA: 140.2 mL (125.1-156.9), OSA: 132.4 mL (126.8-154.7)] and a smaller tongue fat content in PLWH + OSA [11.2% (10.2-12.4)] than in the OSA controls [14.8% (13.2-15.5), P = 0.046]. There was no difference in the dynamic behavior of the UA between the two groups. When pooled together, both static and dynamic imaging metrics could be correlated with measures of UA mechanical properties. Our data suggest similar underlying UA physiology in OSA in subjects with and without HIV.NEW & NOTEWORTHY Obstructive sleep apnea is common in people living with human immunodeficiency virus (HIV), but the underlying mechanisms are unclear. We did not find differences in upper airway morphology using magnetic resonance imaging (MRI) during wake and natural sleep between people living with HIV (PLWH) with obstructive sleep apnea (OSA) and age, gender, and body mass index (BMI)-matched people with OSA but without HIV. Nor were there differences in tongue volume or changes in airway size during inspiration and expiration. MRI-derived anatomy was correlated with measures of airway collapse.

Loop Gain as a Predictor of Blood Pressure Response in Patients Treated for Obstructive Sleep Apnea: Secondary Analysis of a Clinical Trial.

Rationale: Randomized trials have shown inconsistent cardiovascular benefits from obstructive sleep apnea (OSA) therapy. Intermittent hypoxemia can increase both sympathetic nerve activity and loop gain ("ventilatory instability"), which may thus herald cardiovascular treatment benefit. Objectives: To test the hypothesis that loop gain predicts changes in 24-hour mean blood pressure (MBP) in response to OSA therapy and compare its predictive value against that of other novel biomarkers. Methods: The HeartBEAT (Heart Biomarker Evaluation in Apnea Treatment) trial assessed the effect of 12 weeks of continuous positive airway pressure (CPAP) versus oxygen versus control on 24-hour MBP. We measured loop gain and hypoxic burden from sleep tests and identified subjects with a sleepy phenotype using cluster analysis. Associations between biomarkers and 24-h MBP were assessed in the CPAP/oxygen arms using linear regression models adjusting for various covariates. Secondary outcomes and predictors were analyzed similarly. Results: We included 93 and 94 participants in the CPAP and oxygen arms, respectively. Overall, changes in 24-hour MBP were small, but interindividual variability was substantial (mean [standard deviation], -2 [8] and 1 [8] mm Hg in the CPAP and oxygen arms, respectively). Higher loop gain was significantly associated with greater reductions in 24-hour MBP independent of covariates in the CPAP arm (-1.5 to -1.9 mm Hg per 1-standard-deviation increase in loop gain; P ⩽ 0.03) but not in the oxygen arm. Other biomarkers were not associated with improved cardiovascular outcomes. Conclusions: To our knowledge, this is the first study suggesting that loop gain predicts blood pressure response to CPAP therapy. Eventually, loop gain estimates may facilitate patient selection for research and clinical practice. Clinical trial registered with www.clinicaltrials.gov (NCT01086800).

Effectiveness of long-term noninvasive ventilation measured by remote monitoring in neuromuscular disease.

Background and objective: Patients with neuromuscular disease are often treated with home noninvasive ventilation (NIV) with devices capable of remote patient monitoring. We sought to determine whether long-term NIV data could provide insight into the effectiveness of ventilation over time. Methods: We abstracted available longitudinal data for adults with neuromuscular disease in monthly increments from first available to most recent. Generalised linear mixed-effects modelling with subject-level random effects was used to evaluate trajectories over time. Results: 1799 months of data across 85 individuals (median age 61, interquartile range (IQR) 46-71 years; 44% female; 49% amyotrophic lateral sclerosis (ALS)) were analysed, with a median (IQR) of 17 (8-35) months per individual. Over time, tidal volume increased and respiratory rate decreased. Dynamic respiratory system compliance decreased, accompanied by increased pressure support. Compared to volume-assured mode, fixed-pressure modes were associated with lower initial tidal volume, higher respiratory rate and lower pressures, which did not fully equalise with volume-assured mode over time. Compared with non-ALS patients, those with ALS had lower initial pressure support, but faster increases in pressure support over time, and ALS was associated wtih a more robust increase in respiratory rate in response to low tidal volume. Nonsurvivors did not differ from survivors in ventilatory trajectories over time, but did exhibit decreasing NIV use prior to death, in contrast with stable use in survivors. Conclusion: NIV keeps breathing patterns stable over time, but support needs are dynamic and influenced by diagnosis and ventilation mode. Mortality is preceded by decreased NIV use rather than inadequate support during use.