DAYTIME MECHANICAL VENTILATION IN CHRONIC RESPIRATORY INSUFFICIENCY

Chronic respiratory insufficiency (CRI) is associated with nocturnal h ypoventilation. Treatment with noninvasive mechanical ventilation (NIM V) performed overnight relieves symptoms of hypoventilation and improv es daytime blood gases in CRI, In order to test whether the efficacy o f NIMV depends on it being applied during sleep, we conducted a prospe ctive case-controlled study comparing daytime mechanical ventilation ( dMV) in a awake patients with nocturnal mechanical ventilation (nMV) g iven in equal quantities, We enrolled 33 clinically stable patients (a ge 56.1+/-12.1) rs, 20 females, 14 males with CRI due to restrictive l ung and chest wall disorders and neuromuscular disease, Using a prospe ctive case-control design, matched subjects were allocated alternately to dMV and nMV. After 1 month of NIMV there was considerable symptoma tic improvement in both dMV and nMV patients, There were no significan t differences between groups in the improvement in daytime arterial ca rbon dioxide tension (Pa,CO2) (dMV from 75+/-0.6 to 5.7+/-0.6 kPa; nMV from 72+/-05 to 5.8+/-0.5 kPa, p<0.0001) and during the unassisted sp ontaneous night-time ventilation in terms of transcutaneous Pa,CO2 (dM V from 8.4+/-1.2 to 6.6+/-0.7 kPa; nMV from 8.2+/-1.2 to 6.8+/-0.5 kPa , p<0.0001). We conclude that in many respects, when compared to noctu rnal mechanical ventilation? da,time mechanical ventilation in awake p atients is equally effective at reversing chronic respiratory insuffic iency. Since long-term safety issues were not addressed in this study, we recommend that nocturnal mechanical ventilation should remain the modality of choice for noninvasive mechanical ventilation.