BREATHING PATTERN AND RESPIRATORY MECHANICS IN PATIENTS WITH AMYOTROPHIC-LATERAL-SCLEROSIS

The aim of this study was to evaluate the time course of breathing pat tern and respiratory mechanics in patients with amyotrophic lateral sc lerosis (ALS), A study was conducted on 25 out of 38 eligible ALS pati ents. Neurological status, arterial blood gases (ABGs), spirometry, br eathing pattern (minute ventilation (V'E), tidal volume (VT), respirat ory Frequency (fR), duty cycle (duration of inspiration/duration of to tal breathing cycle (tI/ltot)), respiratory drive (P0.1)), respiratory mechanics (oesophageal pressure (Ppl), dynamic compliance (CL,dyn), p ressure time product (PTP) and index (PTI), work of breathing (WOB)), and respiratory muscle (RM) strength as assessed by maximal oesophagea l pressure (Ppl,max) were evaluated at presentation (t0) in all patien ts and after 6 months (t6) in 11 patients. At t0, the mean values of t he degree of neurological impairment were 60+/-20 and 103+/-30 as asse ssed by the Norris scale and Medical Research Council (MRC) score, res pectively. From the time of the first neurological symptom, survival t ime ranged 7-50 months. Diurnal ABGs were normal, A mild restrictive p attern was observed, a forced vital capacity (FVC) <70% of predicted b eing present in 45% of patients, only FVC % pred (r=0,59; p<0,05), for ced expiratory volume in one second (FEV1) I pred (r=0.53; p<0.05) and survival (r=0.64; p<0.05) showing a significant correlation with the Norris scale, A P pl,max <30 cmH(2)O was associated with a significant ly greater mortality, Ppl,max being correlated with survival (r=O.79, p<0.05), At t6, fR, fR/VT, Po.1/Ppl,max, Were significantly increased in comparison to t0, while FVC % pred, vital capacity (VC) % pred, FEV 1 %, pred, VT and Ppl,max were significantly reduced. These results su ggest a progressive deterioration in breathing pattern and in respirat ory muscle strength with progression of disease.