Too Much of Air in the Lungs Results in VILI
According to researchers at the University of Vermont it was found that artificial ventilation should maintain a balance between over inflation and under inflation of the lungs.
If too much of air is pumped in to the lungs then it will result in the over distention of the lungs resulting in ventilator-induced lung injury (VILI). Doctors currently use small amounts of air (low tidal volume) to protect against VILI. But low tidal volumes can lead to progressive closure of the lungs’ air cells, called alveoli, reducing the lung’s ability to exchange gases. One way to reverse closure of the alveoli is to periodically give a more robust puff of air, known as deep inflation.A new study in the online edition of the American Journal of Physiology-Lung Cellular and Molecular Physiology shows that low tidal volume combined with periodic deep inflation provides the best balance between keeping the lung open and preventing VILI in mice. And, using mice, these researchers have shown for the first time that although deep inflation is necessary, it can be overdone.
‘There is still a lot of controversy and uncertainty about how best to ventilate the lung,’ said the study’s senior author, Jason HT Bates of the University of Vermont. ‘One controversy is whether deep inflations, the ‘sighs’ that each of us takes periodically, should ever be given, and if so, how frequently.’
‘This study demonstrates that an optimal frequency range of deep inflation delivery exists, at which point the potentially injurious effects of overdistention are outweighed by the protective benefits of maintaining a predominantly open lung’ wrote Gilman B. Allen, Benjamin T. Suratt, Lisa Rinaldi, Joseph M. Petty and Bates in the AJP-Lung paper entitled ‘Choosing the frequency of deep inflation in mice: balancing recruitment against ventilator-induced lung injury.’ Allen, a medical doctor with Fletcher Allen Health Care and the University of Vermont department of medicine, has treated patients on ventilation. Bates is a University of Vermont department of medicine researcher interested in lung physiology.