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Prevalence of sleep apnoea and capnographic detection of nocturnal hypoventilation in amyotrophic lateral sclerosis
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  • Published on:
    Sleep apnoea and nocturnal hypoventilation in patients with amyotrophic lateral sclerosis

    Boentert et al. investigated the prevalence of sleep apnoea and nocturnal hypoventilation (NH) in 250 patients with non-ventilated amyotrophic lateral sclerosis (ALS) by considering gender and severity of bulbar dysfunction (1). Prevalence of NH and apnoea-hypopnoea index (AHI) >5/hour was 40.0% and 45.6%, respectively, and 22.3% of patients had both NH and sleep apnoea. Sleep apnoea was significantly more common in male patients and negatively associated with bulbar function. I have some concerns with this study.

    First, the authors did not conduct stratified analysis by gender. As the prevalence of sleep apnoea differs by gender, the association between sleep apnoea, NH and severity of bulbar dysfunction should be analyzed by stratification with gender.

    Second, the authors conducted univariate analyses, and adjustment of independent variables cannot be made. Although the number of patients is limited, recommendation for the use of transcutaneous capnography should be based by appropriate adjustments of confounders.

    Finally, Park et al. evaluated the relationship between nocturnal hypoxia and cognitive dysfunction in patients with ALS, and patients with nocturnal hypoxia showed poor memory retention and retrieval efficiency. They speculated that patients with ALS might be exposed to repeated episodes of deoxygenation-reoxygenation during sleep, because of the weakness of the respiratory muscles. In order to evaluate the effect of desaturation on ALS...

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    Conflict of Interest:
    None declared.
  • Published on:
    Classification of respiratory events in amyotrophic lateral sclerosis: diagnostic and therapeutic challenges
    • Grazia Crescimanno, Pneumologist 1 Italian National Research Council, Institute of Biomedicine and Molecular Immunology, Palermo.
    • Other Contributors:
      • Francesca Greco, Sleep technologist
      • Alessandra Sorano, MD
      • Oreste Marrone, Pneumologist

    Dear Editor,
    We read with great interest the article of Boentert et al.1 recently published on this journal. In their paper, the authors describe polysomnographic findings in a large series of non-ventilated patients with amyotrophic lateral sclerosis (ALS). One of the points the authors underscore is that in their patients most respiratory events during sleep were of the obstructive, and not of the central type. This finding is in agreement with what described by Kimura,2 but not by several other authors who found that most respiratory events were of the central type.3 Furthermore, the authors of this paper did not find that obstructive apneas were preferentially associated with bulbar ALS, similarly to David et al.4 but unlike what described by Santos et al.5 However, the tables in the article show that most of the respiratory events were hypopneas, whose type was not specified.
    Criteria for scoring sleep disordered breathing events have changed over time, especially as regards hypopneas. Only recently a general rule for type of hypopnea, central or obstructive has been proposed. Obstructive hypopneas are those where at least one of three criteria is met during the event: presence of snoring, flow limitation demonstrated by a flattening of the nasal pressure derived flow signal, opposing thoracic and abdominal movements. Absence of all these criteria characterizes central hypopneas.6 However, standard criteria for apneas and hypopneas fit well to patients wi...

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    Conflict of Interest:
    None declared.