Correspondence  |   January 2015
In Reply
Author Notes
  • Hospital Privado de Comunidad, Mar del Plata, Argentina (G.T.).
  • (Accepted for publication September 18, 2014.)
    (Accepted for publication September 18, 2014.)×
Article Information
Correspondence   |   January 2015
In Reply
Anesthesiology 01 2015, Vol.122, 214-215. doi:
Anesthesiology 01 2015, Vol.122, 214-215. doi:
Thank you very much for giving us the opportunity to reply the letter by Dr. Girard et al. about our recent paper in Anesthesiology.1  In their interesting letter, Dr. Girard et al. describe different theories about the genesis of B lines in the setting of atelectasis and commented that this very lung sonography (LUS) sign has already been described. Their argument is based on publications related to patients with pre-existing pulmonary diseases and on data derived from ex-vivo animal and laboratory models.2–5  As practicing anesthesiologists who simply apply LUS as a diagnostic tool, we focused our literature search primarily on clinical studies employing LUS and thereby may have missed important evidence coming from primary ultrasound research, however, we do not only agree with the criticism but are grateful to the authors for having raised our awareness for the complexity of LUS.
To our knowledge, the occurrence of anesthesia-induced atelectasis in children has never before been studied by LUS in detail. For this reason, we cannot infer with certainty that the LUS signs—including B lines—found in adults and in atelectasis of different origins are similar to or even identical with the ones we saw in anesthesia-induced atelectasis by compressive mechanism in our children. This lack of reliable information made us define anesthesia-induced atelectasis a posteriori and analyze the prevalence of LUS signs associated with such atelectasis (please see table 11 ). This is the reason why we presented our results—including those related to B lines—as novel contributions to the clinical understanding and diagnosis of atelectasis in children undergoing general anesthesia.
In the second part of their letter, Dr. Girard et al. highlight the role anesthesia-induced atelectasis may play in creating local inflammatory responses within the lungs and in causing postoperative pulmonary complications.6  Such lung inflammation appears any time cyclic ventilation is applied to a partially collapsed lung, the root cause being tidal recruitment (the opening and closing of an atelectatic area during the breathing cycle) and tidal overdistension (the excess volume or pressure that normally aerated areas receive during inspiration).6–9  This sequence of events calls for the use of protective ventilator settings also during anesthesia if such kind of lung injury was to be prevented.10–14  However, even in the light of recent studies, our knowledge on how to best implement protective ventilation strategies is scarce.15,16  These latest attempts to provide convincing scientific support for the hypothesis that particular ventilator settings (a combination of high vs. low tidal volume or high vs. low positive end-expiratory pressure, with and without recruitment maneuvers) would have proven effects on both, the mechanisms of lung injury during anesthesia and on postoperative pulmonary complications failed.
Furthermore, Dr. Girard et al. suggested that the link between atelectasis and postoperative pulmonary complications should be established by an imaging tool capable of detecting atelectasis. We totally agree with this statement. Although the presence of atelectasis might be suspected when respiratory mechanics and gas exchange are suboptimal, in vivo it can only be diagnosed with 100% certainty by imaging means. Therefore, the cited studies fail to demonstrate a causative relationship between particular ventilator settings and atelectasis, let alone postoperative pulmonary complications.
Therefore, before we could address such clinically relevant hypotheses, we first had to validate LUS by magnetic resonance imaging as a noninvasive reliable tool to detect atelectasis—at least in children. Now that LUS has demonstrated its high sensitivity and specificity for diagnosing atelectasis, we have a good chance to reveal tidal recruitment as the main mechanism of ventilator-associated lung injury in partially collapsed lungs. However, due to methodological reasons, LUS will fail as a diagnostic tool when the lungs become overdistended. To detect this other important injurious condition the monitoring of dead space by way of volumetric capnography is a valid option.17,18  Thus, today at least two noninvasive bedside methods are available to detect the main mechanisms of ventilator-induced lung injury. We believe it is about time to start using them in our daily practice for the benefit of our patients.
Competing Interests
The authors declare no competing interests.
Gerardo Tusman, M.D., Cecilia M. Acosta, M.D., Stephan H Bohm, M.D. Hospital Privado de Comunidad, Mar del Plata, Argentina (G.T.).
Acosta, CM, Maidana, GA, Jacovitti, D, Belaunzarán, A, Cereceda, S, Rae, E, Molina, A, Gonorazky, S, Bohm, SH, Tusman, G Accuracy of transthoracic lung ultrasound for diagnosing anesthesia-induced atelectasis in children.. Anesthesiology. (2014). 120 1370–9 [Article] [PubMed]
Lichtenstein, D, Mézière, G, Biderman, P, Gepner, A, Barré, O The comet-tail artifact. An ultrasound sign of alveolar-interstitial syndrome.. Am J Respir Crit Care Med. (1997). 156 1640–6 [Article] [PubMed]
Soldati, G, Copetti, R, Sher, S Sonographic interstitial syndrome: The sound of lung water.. J Ultrasound Med. (2009). 28 163–74 [PubMed]
Soldati, G, Giunta, V, Sher, S, Melosi, F, Dini, C “Synthetic” comets: A new look at lung sonography.. Ultrasound Med Biol. (2011). 37 1762–70 [Article] [PubMed]
Soldati, G, Inchingolo, R, Smargiassi, A, Sher, S, Nenna, R, Inchingolo, CD, Valente, S Ex vivo lung sonography: Morphologic-ultrasound relationship.. Ultrasound Med Biol. (2012). 38 1169–79 [Article] [PubMed]
Tusman, G, Böhm, SH, Warner, DO, Sprung, J Atelectasis and perioperative pulmonary complications in high-risk patients.. Curr Opin Anaesthesiol. (2012). 25 1–10 [Article] [PubMed]
Shennib, H, Mulder, DS, Chiu, RC The effects of pulmonary atelectasis and reexpansion on lung cellular immune defenses.. Arch Surg. (1984). 119 274–7 [Article] [PubMed]
Carney, D, DiRocco, J, Nieman, G Dynamic alveolar mechanics and ventilator-induced lung injury.. Crit Care Med. (2005). 33suppl 3 S122–8 [Article] [PubMed]
Zupancich, E, Paparella, D, Turani, F, Munch, C, Rossi, A, Massaccesi, S, Ranieri, VM Mechanical ventilation affects inflammatory mediators in patients undergoing cardiopulmonary bypass for cardiac surgery: A randomized clinical trial.. J Thorac Cardiovasc Surg. (2005). 130 378–83 [Article] [PubMed]
Michelet, P, D’Journo, XB, Roch, A, Doddoli, C, Marin, V, Papazian, L, Decamps, I, Bregeon, F, Thomas, P, Auffray, JP Protective ventilation influences systemic inflammation after esophagectomy: A randomized controlled study.. Anesthesiology. (2006). 105 911–9 [Article] [PubMed]
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 preexisting lung injury.. Anesthesiology. (2008). 108 46–54 [Article] [PubMed]
Licker, M, Diaper, J, Villiger, Y, Spiliopoulos, A, Licker, V, Robert, J, Tschopp, JM Impact of intraoperative lung-protective interventions in patients undergoing lung cancer surgery.. Crit Care. (2009). 13 R41 [Article] [PubMed]
Hemmes, SN, Serpa Neto, A, Schultz, MJ Intraoperative ventilatory strategies to prevent postoperative pulmonary complications: A meta-analysis.. Curr Opin Anaesthesiol. (2013). 26 126–33 [Article] [PubMed]
Goldenberg, NM, Steinberg, BE, Lee, WL, Wijeysundera, DN, Kavanagh, BP Lung-protective ventilation in the operating room: Time to implement?. Anesthesiology. (2014). 121 184–8 [Article] [PubMed]
Futier, E, Constantin, JM, Paugam-Burtz, C, Pascal, J, Eurin, M, Neuschwander, A, Marret, E, Beaussier, M, Gutton, C, Lefrant, JY, Allaouchiche, B, Verzilli, D, Leone, M, De Jong, A, Bazin, JE, Pereira, B, Jaber, S IMPROVE Study Group, A trial of intraoperative low-tidal-volume ventilation in abdominal surgery.. N Engl J Med. (2013). 369 428–37 [Article] [PubMed]
The PROVE Network Investigators, for the Clinical Trial Network of the European Society of Anaesthesiology, High versus low positive end-expiratory pressure during general anaesthesia for open abdominal surgery (PROVHILO trial): A multicentre randomised controlled trial. Lancet. (2014). 384 495–503 [Article] [PubMed]
Tusman, G, Sipmann, FS, Borges, JB, Hedenstierna, G, Bohm, SH Validation of Bohr dead space measured by volumetric capnography.. Intensive Care Med. (2011). 37 870–4 [Article] [PubMed]
Tusman, G, Sipmann, FS, Bohm, SH Rationale of dead space measurement by volumetric capnography.. Anesth Analg. (2012). 114 866–74 [Article] [PubMed]