Objective: To improve the systematic monitoring of pain and sedation levels following the implementation of a nurse-guided ASP. To determine its influence on medication management and clinical outcomes in critical patient on mechanical ventilation. Method: Cohort study, from March 2013 to May 2015. Patients with mechanical ventilation ? 24 hours and perfusion sedation were included. Variables: demographic characteristics, pain and sedation assessment records, daily dose and frequency of analgosedation use, ventilation times, incidence of ventilator-associated pneumonia (VAP), reintubation, length of stay and mortality in hospital and ICU. Descriptive statistics, Student’s t or U-Mann-Whitney, Chi square or Fisher’s test, significance p?0.05. Results: There were a total amount of 242 patients analyzed, (105 in control group and 137 in protocol group) of 55.1(±15) years old. Women 41%. Registers of pain and sedation/agitation, median (interquartile range): communicative patients [0(0-1) vs 2(0-4): p <0.0001], noncommunicative [0(0-3) vs 3(1-6); p <0.0001]; sedated patients [3(0-13.7) vs 19(8-31.5): p <0.0001]. Sedative dose, median (interquartile range): midazolam [318(231.2-452.6) vs 223(152.8-549.2) mg/day; p=0.001)], propofol [1930(1045-2589) vs 1650(845.8-2090) mg/day; p=0.04)]. Frequency of use: dexmedetomidine (2.8 vs. 15.9%; p=0.001), paracetamol (64.8 vs. 82.6%; p=0.001), metamizole (24.6 vs. 31.4%;p=0.04), morphine (75.9 vs. 61.6%;p=0.017). Ventilation time, median (interquartile range): 4.7(1.9-10.3) vs 4(1.7-8.6) days; p=0.33. Incidence of VAP (25 vs 14%; p=0.02), reintubation (15 vs 9%; p=0.45). Stay, median (interquartile range): ICU [11(7-19) vs 11(7-18) days; p=0.73]; hospital [30.51(18-55) vs 25(16-41) days; p=0.21)]. ICU mortality (13 vs. 4.3%; p=0.01), hospital (16 vs. 10%; p=0.14). Conclusions: In our patient cohort, the raise of pain and sedation/agitation monitoring, has optimized analgesic and sedatives doses and improved clinical outcomes.