Perioperative Protective Ventilatory Strategies in Patients without Acute Lung Injuries
Schultz, Marcus J. M.D., Ph.D., F.C.C.P.*; Gajic, Ognjen M.D., F.C.C.P.
We thank Dr. Licker et al.
for their comments on our article about optimal ventilator strategies in patients without acute lung injury.1
Indeed, overstretching lungs with conventional and abnormally high tidal volumes during surgery has been shown to trigger procoagulant and proinflammatory alveolar responses in patients with healthy lungs, while not being particularly useful to prevent intraoperative atelectasis.2,3
When we consider the concept of “multiple hits” to explain the pathophysiologic mechanisms of acute lung injury, a protective ventilatory strategy (using “normally sized” tidal volume to prevent lung stretch) is certainly indicated in the management of surgical patients with lungs at risk for lung injury (e.g.
, with systemic inflammatory response syndrome, major trauma, major surgery). In this context, we would like to stress that the terminology chosen for a strategy aiming at prevention of overstretching the lungs (conventional vs.
low tidal volumes) is wrong and maybe even misleading. Instead of “lower” tidal volumes, we should use the term “normal” or “normally sized” tidal volumes. It is like traffic speeding: traffic speeding during rush hours is very dangerous—but traffic speeding is always dangerous, even when there are not so many other cars on the road; therefore, regulations mandate that we never drive faster than the speed limit. The size of a normal tidal volume is approximately 6 ml/kg for all mammals4
—we should always consider use of normally sized tidal volumes rather than (very) high tidal volumes.
We agree that ventilation with normal tidal volumes as proposed in our review may not prevent the development of postoperative atelectasis. Although limited evidence supports the use of higher positive end-expiratory pressure, intraoperative recruitment maneuvers, lower oxygen fraction, and postoperative noninvasive ventilation,5
a multimodal lung-protective approach has not been tested.
Although postoperative pulmonary complications are common and associated with significant morbidity, few studies investigated the influence of intraoperative ventilator and nonventilator management (e.g., fluid balance, transfusions). Indeed, randomized controlled trials are needed to answer whether a multimodal lung-protective approach effectively prevents the formation of atelectasis and reduces the incidence of acute lung injury and other pulmonary complications after various types of surgical procedures.
Marcus J. Schultz, M.D., Ph.D., F.C.C.P.,*
Ognjen Gajic, M.D., F.C.C.P.
*Academic Medical Center, Amsterdam, The Netherlands. firstname.lastname@example.org
1. Schultz MJ, Haitsma JJ, Slutsky AS, Gajic O: What tidal volumes should be used in patients without acute lung injury? Anesthesiology 2007; 106:1226–31
2. Choi G, Wolthuis EK, Bresser P, Levi M, van der Poll T, Dzoljic M, Vroom MB, Schultz MJ: Mechanical ventilation with lower tidal volumes and positive end-expiratory pressure prevents alveolar coagulation in patients without lung injury. Anesthesiology 2006; 105:689–95
3. Wolthuis EK, Choi G, Dessing MC, Bresser P, Lutter R, Dzoljic M, van der Poll T, Vroom MB, Hollmann M, Schultz MJ: Mechanical ventilation with lower tidal volumes and positive end-expiratory pressure prevents pulmonary inflammation in patients without preexistent lung injury. Anesthesiology 2008; 108:46–54
4. Tenney SM, Remmers JE: Comparative quantitative morphology of the mammalian lung: Diffusing area. Nature 1963; 197:54–6
5. Whalen FX, Gajic O, Thompson GB, Kendrick ML, Que FL, Williams BA, Joyner MJ, Hubmayr RD, Warner DO, Sprung J: The effects of the alveolar recruitment maneuver and positive end-expiratory pressure on arterial oxygenation during laparoscopic bariatric surgery. Anesth Analg 2006; 102:298–305
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