Negative correlation between respiratory drive and SNIP in amyotrophic lateral sclerosis

Abstract

Respiratory Drive is a neurogenic stimulus for physiologic respiratory activity. It has been shown increased or decreased in different pathological conditions. Aim of this study was to evaluate the respiratory drive in Amyotrophic Lateral Sclerosis (ALS), compared to a healthy population, and to examine possible correlations with arterial blood gas (ABG), or with functional parameters.

We enrolled twenty-three (17 males) consecutive patients affected by ALS, and eighteen (13 males) healthy controls. Both groups were compared with rergard to anthropometrics, ABG, functional parameters, and respiratory drive [mouth occlusion pressure (P0.1), VT/Ti, Ti/Ttot].

In patients affected by ALS, we found an increased level of respiratory drive parameters compared to the control group (P0.1 1.64±1.01 vs. 1.21±0.32; p=0.05. VT/Ti 0.46±0.15 vs. 0.38±0.09; p=0.039). SNIP values higher than 20 cmH2O inversely correlated with mouth occlusion pressure (P0.1) (p=0.016; r²=-0.328) and with VT/Ti (p=0.044, r²=-0.243). It has been also observed a correlation tendency between lower FVC values and increased respiratory drive (p=0.08).

In conclusion, in ALS patients with SNIP higher than 20 cmH2O, we found an augmented respiratory drive activity compared to healthy controls, probably due to a significative reduction of muscular actvity.