Use of Sniff Nasal-Inspiratory Force to Predict Survival in Amyotrophic Lateral Sclerosis

• Published in: American journal of respiratory and critical care medicine Vol. 171; no. 3; pp. 269 - 274
• Main Authors: Morgan, Ross K, McNally, Stephen, Alexander, Michael, Conroy, Ronan, Hardiman, Orla, Costello, Richard W
• Format: Journal Article
• Language: English
• Published: New York, NY Am Thoracic Soc 01-02-2005; American Lung Association; American Thoracic Society
• Subjects: Adult; Aged; Aged, 80 and over; Amyotrophic lateral sclerosis; Amyotrophic Lateral Sclerosis - physiopathology; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Catheters; Clinical trials; Emergency and intensive cardiocirculatory care. Cardiogenic shock. Coronary intensive care; Ent, stomatology, face, injuries. Foreign bodies. Diseases due to physical agents: otorhinolaryngology; Female; Follow-Up Studies; Forecasting; Humans; Hypoxia - physiopathology; Inhalation - physiology; Intensive care medicine; Male; Medical prognosis; Medical sciences; Middle Aged; Mortality; Mouth; Mouth - physiopathology; Muscle strength; Nose - physiopathology; Oxygen saturation; Polyethylene; Prognosis; Proportional Hazards Models; Respiratory failure; Respiratory Paralysis - physiopathology; Sensitivity and Specificity; Sleep - physiology; Spirometry; Survival Rate; Traumas. Diseases due to physical agents; Ventilation; Vital Capacity - physiology; Work of Breathing - physiology; United Kingdom > UK; Nervous system diseases; Intensive care; Respiratory disease; Force; noninvasive ventilation; Amyotrophic lateral sclerosis; Respiratory system; Survival; Respiratory failure; Respiratory muscle; Central nervous system disease; Degenerative disease; Spinal cord disease; Resuscitation; Strength; respiratory muscle strength
• ISSN: 1073-449X; 1535-4970
• DOI: 10.1164/rccm.200403-314OC

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.