Rebuttal From Dr Gattinoni

Abstract

The pro-con format is an ancient academic game. As far as I recall, Galileo was involved at the Padua University in a pro-con debate about the relative motion of the sun and the earth. At the end of a hot debate, several wounded supporters were counted within pro and con factions. Nowadays, a smoother approach is taken, and I would prefer that the mainstream of pro-con debates be the search for the truth under different lights. Knowing his intellectual honesty, I believe that Dr Hubmayr has the same attitude. In fact, at the end of his point editorial, he says, “I suspect that in a normal lung, in the absence of other stressors, the clinical manifestations of high-Vt [tidal volume] ventilation are generally subtle and inconsequential.”1Hubmayr RD Point: is low tidal volume mechanical ventilation preferred for all patients on ventilation? Yes.Chest. 2011; 140: 9-11Abstract Full Text Full Text PDF PubMed Scopus (27) Google Scholar On the other hand, my conclusion of the counterpoint editorial was that “if in a given ICU there is not the possibility of such measurements [stress and strain], a lower Vt/IBW [ideal body weight] would anyway be a better choice than a higher one.”2Gattinoni L Counterpoint: is low tidal volume mechanical ventilation preferred for all patients on ventilation? No.Chest. 2011; 140: 11-13Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar It is quite evident that, although we use different words, we are expressing the same concept; that is, in a busy unit without the possibility of more sophisticated monitoring, a Vt of 7 mL/kg IBW, as suggested by Dr Hubmayr, is a reasonably safe choice. Incidentally, during the 2011 International Symposium on Intensive Care and Emergency Medicine in Brussels, Belgium, in a discussion of a worldwide survey on mechanical ventilation, Dr Esteban3Esteban A. Mechanical ventilation around the world. Paper presented at: ISICEM, 31st International Symposium on Intensive Care and Emergency Medicine, March 22, 2011, Brussels, Belgium.Google Scholar showed that the average Vt used around the world is ≈ 7.2 mL/kg IBW, indicating that Dr Hubmayr is at least in wide, if not good, company. However, the title of our debate was not whether lower Vt, in general, is better than higher (as we all agree) but whether low Vt mechanical ventilation is preferred for all patients on ventilation. I spent all my professional life trying to introduce and promote gentle lung ventilation, starting in the 1970s with a low-frequency ventilation associated with extracorporeal CO2 removal to explicitly provide “lung rest.”4Kolobow T Gattinoni L Tomlinson TA Pierce JE Control of breathing using an extracorporeal membrane lung.Anesthesiology. 1977; 46: 138-141Crossref PubMed Scopus (161) Google Scholar, 5Gattinoni L Agostoni A Pesenti A et al.Treatment of acute respiratory failure with low-frequency positive-pressure ventilation and extracorporeal removal of CO2.Lancet. 1980; 2: 292-294Abstract PubMed Scopus (196) Google Scholar, 6Bartlett RH Gattinoni L Current status of extracorporeal life support (ECMO) for cardiopulmonary failure.Minerva Anestesiol. 2010; 76: 534-540PubMed Google Scholar However, although this approach is still valuable for patients with highly unhomogeneous lung for whom a safe mechanical ventilation is impossible,7Terragni PP Rosboch G Tealdi A et al.Tidal hyperinflation during low tidal volume ventilation in acute respiratory distress syndrome.Am J Respir Crit Care Med. 2007; 175: 160-166Crossref PubMed Scopus (588) Google Scholar on the other extreme of the spectrum, a low Vt ventilation should be avoided in the subgroup of patients with acute lung injury/ARDS. In this patient subgroup, the ventilatable lung volume is not far from normal for which a Vt of 8 to 10 mL/kg IBW results in a transpulmonary pressure of 4 to 6 cm H2O. A lower Vt in these patients would result in the need for sedation, hypercapnia, and reabsorption atelectasis, with increased risk for infection. Therefore, my message is only one: A gentle lung ventilation in a very small sized “baby lung” would mean a Vt/IBW even lower than 6 mL/kg IBW, whereas in a greater sized baby lung it would mean a greater Vt/IBW, adequately monitored. Indeed, gentle and safe ventilation are coincident concepts and require tailoring of Vt on the actual baby lung size.8Gattinoni L Pesenti A The concept of “baby lung.”.Intensive Care Med. 2005; 31: 776-784Crossref PubMed Scopus (520) Google Scholar