Commentary by Danise Schiliro-Chuang MD, NYU Chief Resident
Hello and welcome to this week’s shortcuts. Let’s jump right to what’s new in the journals.
Two large, multicenter, randomized controlled studies published in the February 13 issue of JAMA show that patients with acute lung injury may benefit from higher positive end-expiratory pressures (PEEP). In the first study by Meade et al. the control arm received low target tidal volumes of 6ml/kg, plateau airway pressures not exceeding 30cm H20 and conventional levels of PEEP. The experimental arm received a strategy based on the “open-lung approach,” combining the same low tidal volumes as above in addition to plateau pressures not exceeding 40 cm H20, recruitment maneuvers and higher PEEP. Mean PEEP levels on day 1 were 10.1 cm H2O and 15.6 cm H2O in the control and experimental arms, respectively. While the primary outcome, all-cause hospital mortality, was similar in the 2 groups, the “open-lung” strategy group had lower rates of both refractory hypoxemia and death with refractory hypoxemia. In addition, barotrauma rates were similar in the 2 groups. In the second study by Mercat et al. patients with acute lung injury received either a “minimal distension” strategy, where moderate PEEP was used, or an “increased recruitment” strategy, where higher PEEP was set to reach a plateau pressure of 28 to 30 cm H20 in order to limit hyperinflation. Mean PEEP levels on day 1 were 8.4 cm H2O and 15.8 cm H2O in the minimal distension and increased recruitment groups, respectively. Once again, mortality at 28 days was similar in the 2 groups; however, the increased recruitment group had improved secondary outcomes related to lung function, duration of mechanical ventilation and the duration of organ failure. Thus, while mortality is not affected, data from these 2 studies favors the use of higher levels of PEEP in the early phase of acute lung injury.
Now on to some less refreshing news. A study published in the February 20 issue of JAMA suggests that nights and weekends are not the best times to have a cardiac arrest in a hospital. This multicenter registry of in-hospital cardiac arrests showed that survival rates were significantly lower during nights and weekends, even when adjusted for potentially confounding patient and hospital characteristics. While the authors are unable to provide an explanation for this finding and note that the mechanism is likely multifactorial, they suggest that differences in health care staff, hospital staffing and operational factors need to be examined in order to improve patient safety and survival following cardiac arrests during nights and weekends.
I would never end things on a negative note so let’s finish up with a basic science study that could lead to major clinical implications. A study published online this week from Nature Biotechnology showed that pancreatic endoderm derived from human embryonic stem cells efficiently generates glucose-responsive, insulin-secreting endocrine cells after implantation into mice. This study also received media attention in the New York Times this week. Although human embryonic stem cells have been turned into insulin-producing cells in culture dishes in the past, this marks the first study to show insulin production in response to glucose in animals. While a small number of mice developed teratomas and some concerns have been raised about the ability of these precursor cells to reproducibly have the same effects in humans, this work done by scientists at the biotechnology company Novocell, raises the hope that these embryonic cells might one day be used to treat diabetes in humans.