Evaluation of an intervention to reduce tidal volumes in ventilated ICU patients.

BACKGROUND: There is considerable evidence that the use of tidal volumes <6 ml kg(-1) predicted body weight (PBW) reduces mortality in mechanically ventilated patients. We evaluated the effectiveness of using a large screen displaying delivered tidal volume in ml kg(-1) (PBW) for reducing tidal volumes. METHODS: We assessed the intervention in two 6-month periods. A qualitative study was undertaken after the intervention period to examine staff interaction with the intervention. The study was conducted in a mixed medical and surgical intensive care unit at University Hospitals Bristol, UK. Consecutive patients requiring controlled mechanical ventilation for more than 1 h were included. Alerts were triggered when tidal volume breached predetermined targets and these alerts were visible to ICU clinicians in real time. RESULTS: A total of 199 patients with 7640 h of data were observed during the control time period and 249 patients with 10 656 h of data were observed in the intervention period. Time spent with tidal volumes <6 ml kg(-1) PBW increased from 17.5 to 28.6% of the period of controlled mechanical ventilation. Time spent with a tidal volume <8 ml kg(-1) PBW increased from 60.6 to 73.9%. The screens were acceptable to staff and stimulated an increase in attendance of clinicians at the bedside to adjust ventilators. CONCLUSIONS: Changing the format of data and displaying it with real-time alerts reduced delivered tidal volumes. Configuring information in a format more likely to result in desired outcomes has the potential to improve the translation of evidence into practice.

Dynamics of allograft fibrosis in pediatric liver transplantation.

Progressive liver allograft fibrosis (LAF) is well known to occur long term, as shown by its high prevalence in late posttransplant liver biopsies (LBs). To evaluate the influence of clinical variables and immunosuppression on LAF progression, LAF dynamic was assessed in 54 pediatric liver transplantation (LT) recipients at 6 months, 3 and 7 years post-LT, reviewing clinical, biochemical data and protocol LBs using METAVIR and the liver allograft fibrosis score, previously designed and validated specifically for LAF assessment. Scoring evaluations were correlated with fibrosis quantification by morphometric analysis. Progressive LAF was found in 74% of long-term patients, 70% of whom had unaltered liver enzymes. Deceased grafts showed more fibrosis than living-related grafts (p = 0.0001). Portal fibrosis was observed in correlation with prolonged ischemia time, deceased grafts and lymphoproliferative disease (p = 0.001, 0.006 and 0.012, respectively). Sinusoidal fibrosis was correlated with biliary complications (p = 0.01). Centrilobular fibrosis was associated with vascular complications (p = 0.044), positive autoantibodies (p = 0.017) and high gamma-globulins levels (p = 0.028). Steroid therapy was not associated with reduced fibrosis (p = 0.83). LAF could be viewed as a dynamic process with mostly progression along the time. Peri- and post-LT-associated factors may condition fibrosis development in a specific area of the liver parenchyma.

Novel histologic scoring system for long-term allograft fibrosis after liver transplantation in children.

The existing systems for scoring fibrosis were not developed to evaluate transplanted livers. Our aim was to design and validate a novel fibrosis scoring system specifically adapted to assess liver allograft fibrosis (LAF). Clinical data, histology, transient elastography (TE) and AST/platelet ratio index (APRI) were reviewed in 38 pediatric liver transplant (LT) recipients. Protocol liver biopsies performed at 6 months and 7 years post-LT were reviewed by three pathologists who assessed LAF using the METAVIR and Ishak systems. LAF was also scored separately in portal (0-3), sinusoidal (0-3) and centrolobular areas (0-3). Scoring evaluations were correlated with fibrosis quantification using morphometry, and also with TE and APRI. Statistical correlations between morphometry and METAVIR were 0.571 (p < 0.000) and 0.566 (p < 0.000) for the Ishak system. The novel score (0-9) for separate assessment of portal, sinusoidal and centrolobular fibrosis showed a better correlation with morphometry (0.731; p < 0.000) and high intra-/interobserver agreement (0.966; p < 0.000 and 0.794; p < 0.000, respectively). No correlation was found between TE or APRI and morphometry or the three histologic scores. In conclusion, this novel semiquantitative fibrosis scoring system seems to more accurately reflect LAF than the existing scoring system and may become a practical tool for staging fibrosis in LT.

An assessment of the efficiency of the Glostavent ventilator.

In parts of the world where supplies of oxygen and electricity are erratic, ventilating patients' lungs can be problematic. Should the electricity supply fail, gas driven ventilators have an advantage as they can continue functioning. However, many are extravagant in their requirement for the driving gas. The Glostavent ventilator was designed to minimise these requirements. We measured the duration of ventilation achieved by the Glostavent ventilator using an E-size oxygen cylinder at a range of minute volumes, and the inspired oxygen concentration achieved by recycling the driving gas. The period of mechanical ventilation from a single E-size cylinder ranged from 11 h 8 min (SD 4 min) with a minute volume of 7 l min(-1) to 18 h 15 min (SD 7 min) with a minute volume of 3 l min(-1). The mean fractional inspired oxygen concentration achieved by recycling the driving gas without further inspired oxygen supplementation was 0.33. We conclude that the Glostavent ventilator performs as efficiently and cost effectively as predicted.

Living-related versus deceased donor pediatric liver transplantation: a multivariate analysis of technical and immunological complications in 235 recipients.

Timely access to a living donor (LD) reduced pretransplant mortality in pediatric liver transplantation (LT). We hypothesized that this strategy may provide better posttransplant outcome. Between July 1993 and April 2002, 235 children received a primary LT from a LD (n = 100) or a deceased donor (DD) (n = 135). Demographic, surgical and immunological variables were compared, and respective impact on posttransplant complications was studied using a multivariate analysis. Five-year patient survival rates were 92% and 85% for groups LD and DD, respectively (p = 0.181), the corresponding graft survival rates being 89% and 77% (p = 0.033). At multivariate analysis: (1) type of donor (DD) was correlated with higher rate of artery thrombosis (p < 0.012); (2) biliary complication rate at 5 years was 29% and 23% for groups LD and DD, respectively (p = 0.451); (3) lower acute rejection incidence could be correlated with type of donor (DD) (p = 0.001), and immunosuppressive therapy (tacrolimus) (p < 0.001). We conclude that (1) according to the multivariate analysis, LT with LD provided similar patient and graft outcome, when compared to DD; (2) a higher rate of artery thrombosis and a lower rate of rejection were observed in group DD; (3) this study confirms the efficacy of tacrolimus for immunoprophylaxis, whatever the type of organ donor is.

The paediatric liver transplantation program at the Université catholique de Louvain.

The Paediatric Liver Transplant Program at Saint-Luc University Clinics constitutes a substantial single centre experience, including 667 transplantations performed between March 1984 and April 2003, and the history of this program reflects the tremendous progress in this field since twenty years. Liver transplantation in children constitutes a considerable undertaking and its results depend on multiple, intermingled risk factors. An analysis of the respective impact of several surgical and immunological parameters on patient/graft outcome and allograft rejection after paediatric liver transplantation showed a significant learning curve effect as well as the respective impact of pre-transplant diagnosis on survival and of primary immunosuppression on the rejection incidence. The introduction of living related liver transplantation in 1993 not only permitted to provide access to liver replacement in as many as 74% more candidate recipients, but also resulted in better graft survival and reduced retransplantation rate. The results of a recent pilot study suggest that steroid avoidance is not harmful, and could even be beneficial for paediatric liver recipients, particularly regarding growth, and that combining tacrolimus with basiliximab (anti-CD25 chimeric monoclonal antibody) for steroid substitution appears to constitute a safe alternative in this context. The long-term issues represent the main future challenges in the field, including the possibility of a full rehabilitation through immunosuppression withdrawal and tolerance induction, the development of adolescence transplant medicine, and the risk of early atherogenesis in the adulthood.