Use of Sniff nasal-inspiratory force to predict survival in amyotrophic lateral sclerosis

Am J Respir Crit Care Med. 2005 Feb 1;171(3):269-74. doi: 10.1164/rccm.200403-314OC. Epub 2004 Oct 29.


Respiratory muscle weakness is the usual cause of death in amyotrophic lateral sclerosis. The prognostic value of the forced vital capacity (FVC), mouth-inspiratory force, and sniff nasal-inspiratory force were established in a group of 98 patients with amyotrophic lateral sclerosis who were followed trimonthly for 3 years. Sniff nasal-inspiratory force correlated with the transdiaphragmatic pressure (r = 0.9, p < 0.01). Sniff nasal-inspiratory force was most likely to be recorded at the last visit (96% of cases), compared with either the FVC or mouth-inspiratory force (86% and 81%, respectively, p < 0.01). A sniff nasal-inspiratory force less than 40 cm H(2)O was significantly related with nocturnal hypoxemia. When sniff nasal-inspiratory force was less than 40 cm H(2)O, the hazard ratio for death was 9.1 (p = 0.001), and the median survival was 6 +/- 0.3 months. The sensitivity of FVC < 50% for predicting 6-month mortality was 58% with a specificity of 96%, whereas sniff nasal-inspiratory force less than 40 H(2)O had a sensitivity of 97% and a specificity of 79% for death within 6 months. Thus the sniff nasal-inspiratory force test is a good measure of respiratory muscle strength in amyotrophic lateral sclerosis, it can be performed by patients with advanced disease, and it gives prognostic information.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Amyotrophic Lateral Sclerosis / physiopathology*
  • Female
  • Follow-Up Studies
  • Forecasting
  • Humans
  • Hypoxia / physiopathology
  • Inhalation / physiology*
  • Male
  • Middle Aged
  • Mouth / physiopathology
  • Nose / physiopathology*
  • Prognosis
  • Proportional Hazards Models
  • Respiratory Paralysis / physiopathology
  • Sensitivity and Specificity
  • Sleep / physiology
  • Spirometry
  • Survival Rate
  • Vital Capacity / physiology
  • Work of Breathing / physiology