Overnight Pulse Oximetry to Determine Prognostic Factors in Subjects With Amyotrophic Lateral Sclerosis

Abstract

BACKGROUND: The objective of the current study was to determine whether overnight pulse oximetry in patients with amyotrophic lateral sclerosis is prognostic of the onset of awake respiratory failure and hospital admissions. METHODS: This was an observational study in a cohort of subjects with amyotrophic lateral sclerosis. The study included subjects with a baseline S pO 2 6 94% on home overnight pulse oximetry testing. Patients age 6 80 y and those with comorbidities and with poor short-term prognosis or sleep apnea were excluded. The subjects were classified as nocturnal desaturators according to percentage of sleep time with S pO 2 < 90% (T90) > 10%. RESULTS: A total of 76 subjects were included: 40 men (53%), mean 6 SD age 60 6 14.4 y, mean 6 SD body mass index 25.7 6 4.60 kg/m 2 , and spinal presentation in 63.2%. After overnight pulse oximetry, 20 subjects (26%) were classified as desaturators and 56 (74%) as non-desaturators. In the first year, the subjects with nocturnal desaturation had respiratory failure more often compared with the subjects without desaturation (35% vs 10.91%; P 5 .02) and had a higher risk of developing respiratory failure during the course of the study (hazard ratio 2.48; P 5 .030). The desaturator group also had a higher rate of 6 1 admission (40% vs 7.3%; P 5 .01) and a higher likelihood of respiratory-related hospitalization (hazard ratio 2.41; P 5 .02). Median survival was almost 1 year less if T90 > 10% was observed in the overnight pulse oximetry: 21 months versus 32 months survival if T90 was^10%. CONCLUSIONS: In subjects with amyotrophic lateral sclerosis, nocturnal desaturation conferred a higher risk of respiratory failure and poorer prognosis. Even in the absence of other clinical criteria, early pulse oximetry should be performed and the need for nocturnal ventilatory support assessed.

Monitoring Systems in Home Ventilation

“…Amongst the sensors currently commercially available, there is a large discrepancy in frequency ranging from one recording per second to one recording every 12 s. This setting affects the results provided by the statistics and the ease of visually inspecting the curves. Beside these limitations, nocturnal pulse oximetry can be used to screen for nocturnal respiratory events [ 15 ], to predict the outcome [ 16 , 17 ], and to monitor patients using NIV at night. Sensibility and specificity are not optimal when pre-test probability of having a specific disease is low.…”

Sleep disorders in Amyotrophic Lateral Sclerosis

“…al describing prognosticating factors for development of respiratory insufficiency in patients with ALS, reported longer diagnostic delay, advanced age at diagnosis, bulbar onset of symptoms, lower FVC, low body mass index and low dyspnea subscore or ALS functional rating scale (ALSFRS-R) were associated with development of respiratory failure (50). Another study reported nocturnal oxygen desaturations were associated with development of respiratory failure and worse prognosis (51).…”

Sleep and Sleep Disruption in Amyotrophic Lateral Sclerosis

“…In two recent studies, several factors have been found to be associated with early onset and rapid deterioration of respiratory insufficiency, including higher age at diagnosis, longer diagnostic delay, lower FVC and body mass index, bulbar onset of symptoms, and a lower ALS functional rating scale (ALSFRS-R) total score or dyspnea subscore, respectively [80, 81•]. Another study showed that nocturnal oxygen desaturations are also associated with respiratory failure and worse prognosis [82].…”