Intraoperative ventilation NEJM Study

[BLADEMDA]

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In a study comparing conventional with protective ventilation in critically ill patients without lung injury, de Oliveira and colleagues7 randomized patients to ventilation with either 10–12 or 6–8 ml kg−1 predicted body weight. In both groups, a PEEP of 5 cm H2O applied and the inspired oxygen fraction (FIO2) titrated to keep haemoglobin oxygen saturations (SpO2) above 90%. At 12 h post-ventilation, inflammatory markers in bronchoalveolar lavage fluid [tumour necrosis factor-α (TNF-&#945😉 and IL-8] were significantly higher in the larger tidal volume group. Choi and colleagues8 compared 12 ml kg−1 without PEEP vs 6 ml kg−1 with 10 cm H2O PEEP and showed procoagulant changes in lavage fluid of the larger tidal volume group after 5 h of mechanical ventilation. A recent randomized controlled trial in 150 critically ill patients without ALI compared tidal volumes of 10 vs 6 ml kg−1 predicted body weight.9 The primary endpoints were cytokine levels in bronchoalveolar lavage fluid and plasma and the secondary endpoint was the development of lung injury. The trial was terminated early because the development of lung injury was significantly higher in the larger tidal volume group compared with the lower tidal volume group (13.5% vs 2.6%). The larger tidal volumes were also associated with sustained increase in plasma inflammatory cytokines.

http://bja.oxfordjournals.org/content/105/suppl_1/i108.full.pdf

 

[Idiopathic]

So there is some data to support large tv + peep > peep ( in terms of preventing atelectasis ) ? .this makes me think that larger tidal volumes protective against atelectasis....but an article I was reading compared 6cc/kg to 10 cc/kg and found similar rates of atelectasis....maybe you need even larger Tv's?

I seem to remember somebody explaining to me that delivering a large tv to a lung does not help atelectasis because the collapsed lung has higher resistance to flow and is less compliant than the already open areas which makes the large delivered tv unevenly distributed (favoring he non atelectatic lung). In essence you're just sending more volume to the already open alveoli. ....now I could be totally wrong because I get these things mixed up all the time...maybe vent can chime in.

there is data to support almost anything, especially when it comes to this subject. in between the alveoli that are going to stay open and the ones that are going to stay closed, there is a third group that may be recoverable, but also may be injured. kind of a fine line, its likely beneficial to avoid high tidal volumes and use some PEEP.

 

[bkell101]

Ironically this is going to be our journal club this week for my program

 

[Planktonmd]

Like many things in medicine this is an issue that still requires more research.
The first step is to admit that we really don't know the right answer and to keep an open mind.
It is extremely naive and arrogant to take the newly published studies as indisputable facts.
We are trying to mimic the dynamics of normal respiratory physiology and so far we have failed miserably.

 

[BLADEMDA]

The preponderance of the evidence (many peer reviewed publications) suggest that a low today volume strategy with peep and recruitment maneuvers is most likely superior to the old, conventional ventilation technique in the operating room. The evidence strongly suggest that we alter our practice in higher risk patients and adhere to that new strategy.

Since I practice evidence based medicine I have altered my practice and now insist my CRNAs do the same. Over the decades I have made it a point to advance my practice based on evidence based medicine. This includes the use of U/S for blocks and lines, avoidance of normal saline and Hextend and now, adherence to a lung protection strategy in the operating room.

As the evidence for my practice changes (solid, multiple studies) so too must I change with it.