PReVENT - protective ventilation in patients without ARDS at start of ventilation: study protocol for a randomized controlled trial

Background It is uncertain whether lung-protective mechanical ventilation using low tidal volumes should be used in all critically ill patients, irrespective of the presence of the acute respiratory distress syndrome (ARDS). A low tidal volume strategy includes use of higher respiratory rates, which could be associated with increased sedation needs, a higher incidence of delirium, and an increased risk of patient-ventilator asynchrony and ICU-acquired weakness. Another alleged side-effect of low tidal volume ventilation is the risk of atelectasis. All of these could offset the beneficial effects of low tidal volume ventilation as found in patients with ARDS. Methods/Design PReVENT is a national multicenter randomized controlled trial in invasively ventilated ICU patients without ARDS with an anticipated duration of ventilation of longer than 24 hours in 5 ICUs in The Netherlands. Consecutive patients are randomly assigned to a low tidal volume strategy using tidal volumes from 4 to 6 ml/kg predicted body weight (PBW) or a high tidal volume ventilation strategy using tidal volumes from 8 to 10 ml/kg PBW. The primary endpoint is the number of ventilator-free days and alive at day 28. Secondary endpoints include ICU and hospital length of stay (LOS), ICU and hospital mortality, the incidence of pulmonary complications, including ARDS, pneumonia, atelectasis, and pneumothorax, the cumulative use and duration of sedatives and neuromuscular blocking agents, incidence of ICU delirium, and the need for decreasing of instrumental dead space. Discussion PReVENT is the first randomized controlled trial comparing a low tidal volume strategy with a high tidal volume strategy, in patients without ARDS at onset of ventilation, that recruits a sufficient number of patients to test the hypothesis that a low tidal volume strategy benefits patients without ARDS with regard to a clinically relevant endpoin

Early determinants of long-term T-cell reconstitution after hematopoietic stem cell transplantation for severe combined immunodeficiency

The immune system of patients with severe combined immunodeficiency (SCID) reconstitutes to a large extent during the first years after hematopoietic stem cell transplantation (HSCT). It was suggested, however, that accelerated loss of thymus output may cause impaired immune function at the long term. To address this issue, we studied patients with SCID who underwent allogeneic HSCT 5 to 32 years earlier and identified early determinants of long-term T-cell reconstitution. A variety of immune parameters were analyzed both early (1-4 years) and late (5-32 years) after HSCT. Late after HSCT, a clear distinction could be made between a group of 8 patients with impaired T-cell reconstitution and 11 patients with good immune reconstitution. Importantly, in patients with decreased long-term T-cell reconstitution, T-cell recovery was already poor early after HSCT, demonstrating that long-term immune failure was not caused by accelerated loss of thymus output or long-term graft failure, but resulted from poor early grafting. The number of T-cell receptor excision circles (TRECs) early after HSCT was most predictive for long-term T-cell reconstitution. Frequent monitoring of T-cell immunity and TREC numbers early after HSCT may thus serve to timely identify patients who will fail to reconstitute properly and who may need additional treatmen

Effect of a Low vs Intermediate Tidal Volume Strategy on Ventilator-Free Days in Intensive Care Unit Patients Without ARDS: A Randomized Clinical Trial

Importance: It remains uncertain whether invasive ventilation should use low tidal volumes in critically ill patients without acute respiratory distress syndrome (ARDS). Objective: To determine whether a low tidal volume ventilation strategy is more effective than an intermediate tidal volume strategy. Design, Setting, and Participants: A randomized clinical trial, conducted from September 1, 2014, through August 20, 2017, including patients without ARDS expected to not be extubated within 24 hours after start of ventilation from 6 intensive care units in the Netherlands. Interventions: Invasive ventilation using low tidal volumes (n = 477) or intermediate tidal volumes (n = 484). Main Outcomes and Measures: The primary outcome was the number of ventilator-free days and alive at day 28. Secondary outcomes included length of ICU and hospital stay; ICU, hospital, and 28- and 90-day mortality; and development of ARDS, pneumonia, severe atelectasis, or pneumothorax. Results: In total, 961 patients (65% male), with a median age of 68 years (interquartile range [IQR], 59-76), were enrolled. At day 28, 475 patients in the low tidal volume group had a median of 21 ventilator-free days (IQR, 0-26), and 480 patients in the intermediate tidal volume group had a median of 21 ventilator-free days (IQR, 0-26) (mean difference, -0.27 [95% CI, -1.74 to 1.19]; P =.71). There was no significant difference in ICU (median, 6 vs 6 days; 0.39 [-1.09 to 1.89]; P =.58) and hospital (median, 14 vs 15 days; -0.60 [-3.52 to 2.31]; P =.68) length of stay or 28-day (34.9% vs 32.1%; hazard ratio [HR], 1.12 [0.90 to 1.40]; P =.30) and 90-day (39.1% vs 37.8%; HR, 1.07 [0.87 to 1.31]; P =.54) mortality. There was no significant difference in the percentage of patients developing the following adverse events: ARDS (3.8% vs 5.0%; risk ratio [RR], 0.86 [0.59 to 1.24]; P =.38), pneumonia (4.2% vs 3.7%; RR, 1.07 [0.78 to 1.47]; P =.67), severe atelectasis (11.4% vs 11.2%; RR, 1.00 [0.81 to 1.23]; P =.94), and pneumothorax (1.8% vs 1.3%; RR, 1.16 [0.73 to 1.84]; P =.55). Conclusions and Relevance: In patients in the ICU without ARDS who were expected not to be extubated within 24 hours of randomization, a low tidal volume strategy did not result in a greater number of ventilator-free days than an intermediate tidal volume strategy. Trial Registration: ClinicalTrials.gov Identifier: NCT02153294