[Evolution of patient safety culture in a medium-stay hospital: monitoring indicators]. / Evolución de la cultura de seguridad del paciente en un hospital de media-larga estancia: indicadores de seguimiento.

BACKGROUND: Patient safety is a challenge for health care. The aim of this study is to identify the dimensions with the greatest impact on patient safety culture of healthcare staff in a medium-stay hospital; to asses its evolution over time and to check the sensitivity of monitoring indicators. METHODS: Two cross-sectional studies (2013 to 2015) were conducted. The safety culture assessment tool used was the Spanish version of the "Hospital Survey on Patient Safety" (AHRQ). Outcome variable is high perception of safety (score = 75th percentile). INDEPENDENT VARIABLES: socio-demographic characteristics and perceptions of the evaluated dimensions. The association between variables was quantified by Odds Ratio. RESULTS: The mean of perceived safety was similar in both studies: (7.81 and 7.48, N2013= 66; N2015=92). The best aspects evaluated were: "Supervisor actions" and "Teamwork within unit"; the worst evaluated were: "Staffing", "Management support" and "Teamwork across units". Socio-demographic variables had little significance, while a positive perception in some of the considered dimensions was associated with high perceived safety. The most strongly associated aspects were: "Supervisor actions", "Communication openness" and "Problems in transitions". In the comparative study, indicators based on individual dimensions detected changes better than the assessment of the degree of perceived safety. CONCLUSION: The regular assessment of Patient Safety Culture makes it possible to know the status and evolution of professionals' perceptions. The choice of appropriate indicators optimises the information obtained through these surveys.

Fast vesicle transport in PC12 neurites: velocities and forces.

Although the mechanical behavior of single-motor protein molecules such as kinesin has been carefully studied in buffer, the mechanical behavior of motor-driven vesicles in cells is much less understood. We have tracked single vesicles in neurites of PC12 cells with a spatial precision of +/-30 nm and a time resolution of 120 ms. Because the neurites are thin, long, straight, and attached to the surface of planar cover glasses, the velocity of individual vesicles could be measured for times as long as 15 s and distances as long as 15 mum. The velocity of anterograde vesicles was in most cases constant for periods of 1-2 s, then changed in a step-like fashion to a new constant velocity. The viscoelastic modulus felt by the vesicles within live PC12 cells was determined from the Brownian motion, using Mason's generalization of the Stokes-Einstein equation. From Stokes' law, the drag force at the smallest sustained velocity was 4.2+/-0.6 pN for vesicles of radius 0.30-0.40 mum, about half the maximum force which conventional kinesin can develop during bead assays in buffer. We interpret the observed velocity steps as changes of +/-1 or occasionally +/-2 in the number of active motor proteins dragging that vesicle along a microtubule. Assuming that the motor is conventional kinesin, which hydrolyzes one ATP per 8 nm step along the microtubule, the motor protein efficiency in PC12 neurites is approximately 35%.