The literature to date indicates that noninvasive positive pressure ventilation (NIPPV) provides effective noninvasive ventilator support, prolongs survival, and improves quality of life (QOL) in Amyotrophic Lateral Sclerosis (ALS) patients. It is generally recommended to patients when their pulmonary function testing demonstrates a drop to 50% forced vital capacity (FVC). One result of using NIPPV may be a reduction in the work of the breathing which would lead to decreased caloric needs. However, the work of breathing and the effects of noninvasive ventilation on caloric use have not been studied in patients with ALS. This is extremely important since there may be a reduction in the caloric needs when ALS patients are placed on NIPPV and if the caloric intake is not adjusted, overfeeding can occur. Overfeeding with too many calories can lead to an increase in carbon dioxide which would actually worsen the respiratory failure.
The overall aim of this project is to evaluate how many calories are used by ALS patients while at rest, when placed on NIPPV, and when breathing against a resistance. This will be accomplished using a metabolic cart during these activities. At present, the metabolic cart is routinely used in ALS patients at the time of feeding tube placement to calculate caloric needs. Using the cart to calculate the caloric expenditure on and off the ventilator will aid in calculating the work of breathing and the effects of NIPPV on work of breathing.