Canadian Respiratory Journal
Volume 2019 (2019), Article ID 2679513, 2 pages
https://doi.org/10.1155/2019/2679513

Letter to the Editor

Comment on “Tapered Cuff versus Conventional Cuff for Ventilator-Associated Pneumonia in Ventilated Patients: A Meta-Analysis of Randomized Controlled Trials”

Bert Maertens¹ and Stijn Blot1,2

¹Ghent University, Department of Internal Medicine, De Pintelaan 185, 9000 Ghent, Belgium
²University of Queensland, Burns Trauma and Critical Care Research Centre, Level 9, UQ Health Sciences Building, Royal Brisbane and Women’s Hospital, Herston, QLD 4029, Australia

Correspondence should be addressed to Bert Maertens; bert.maertens@ugent.be

Received 27 February 2019; Accepted 22 May 2019; Published 7 July 2019

Academic Editor: Rocco Trisolini

Copyright © 2019 Bert Maertens and Stijn Blot. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Despite progress in the field of infection prevention, avoiding ventilator-associated pneumonia (VAP) remains challenging. In this regard, we read with great interest the recently published paper by Huang et al. and would like to compliment the authors on this interesting meta-analysis [1].

Innovations in endotracheal tube design have emerged in an effort to avoid the microaspiration of contaminated oropharyngeal secretions, the main pathogenic mechanism for pneumonia development. Most of these innovations show promising results in laboratory settings, but often fail to translate this to clinically important benefits. While ultrathin polyurethane (PU) cuffs and taper-shaped cuffs are capable of reducing microaspiration, they fail to reduce pneumonia incidence in long-term ventilated patients [1–3]. We believe this is because a better sealing cuff leads to overabundant accumulation of subglottic secretions. In combination with short episodes of underinflation, this may lead to massive microaspiration, thereby nullifying any effect of temporarily improved sealing. Accordingly, both subglottic secretion drainage (SSD) and continuous cuff pressure regulation have shown to be effective in pneumonia prevention [4, 5].

The overall findings of Huang et al. are similar to those we found earlier [1, 3]. However, we were surprised to see data differed significantly between our review and the one by Huang et al. (Table 1). Two of these differences are due to a different search strategy. While our review included two studies without full publication [6, 7], Huang et al. did not search for unpublished work. The third difference is the data reported for the study by Philippart et al. [8]. They compared four groups; PU tapered, polyvinylchloride (PVC) tapered, PU cylindrical, and PVC cylindrical cuffs. We chose to combine both tapered groups and both cylindrical groups, while Huang et al. chose only to consider the PVC groups.

Table 1: Differences between data reported in the review of Huang et al. vs. that of Maertens et al.

Study
Huang et al.
Maertens et al.
Reason for difference

Tapered
Standard
Tapered
Standard

E
T
E
T
E
T
E
T

Bent et al.
Not included
0
37
1
43
Unpublished study

Mahmoodpoor et al., 2013
6
32
7
32
6
32
7
32
No difference

Saito et al.
Not included
23
106
23
106
Unpublished study

Philippart et al.
17
129
14
129
33
162
38
163
Huang et al. only considered PVC cuffed tubes

Monsel et al.
10
52
8
57
15
52
16
57
Data error

Jailette et al.
33
162
38
163
33
162
38
163
No difference

Mahmoodpoor et al., 2017
30
138
46
138
Not included
SSD applied in tapered group

E: events; T: total; PVC: polyvinylchloride; SSD: subglottic secretion drainage.

We argue, however, that the last two differences are, in our opinion, due to erroneous comparisons by Huang et al. First of all, we believe the data reported for the study by Monsel et al. are wrong [9]. Huang et al. seem to have used the number of second postoperative pneumonia episodes, instead of the total number of microbiologically confirmed pneumonia episodes, as we did. Secondly, Huang et al. include a study by Mahmoodpoor et al. that was not included in our analysis [10]. We excluded this study because the two endotracheal tubes that were compared differed not only with regard to the shape of the cuff. In the tapered cuffed tubes, SSD was applied while this was not the case in the standard cuffed tubes. Since there is convincing evidence that SSD reduces VAP incidence, we believe that the difference observed in the study is largely attributable to SSD [5]. Not unexpectedly, this study is the only one of the five studies included in the meta-analysis of Huang et al. that found a significant difference in VAP incidence between both groups.

Nevertheless, we agree with the authors that there is no evidence that taper-shaped cuffs provide any benefit on clinically important outcomes. However, as highlighted above, we believe this might be due to accumulation of secretions above a better sealing cuff. The effect of taper-shaped cuffs vs. standard cuffs with concomitant use of SSD and/or continuous cuff pressure regulation remains largely unexplored.

Conflicts of Interest

On behalf of all authors, the corresponding author states that there are no ethical or financial conflicts of interest.

References

W. M. Huang, X. A. Huang, Y. P. Du et al., “Tapered cuff versus conventional cuff for ventilator-associated pneumonia in ventilated patients: a meta-analysis of randomized controlled trials,” Canadian Respiratory Journal, vol. 2019, Article ID 7876417, 7 pages, 2019.

S. I. Blot, J. Rello, and D. Koulenti, “The value of polyurethane-cuffed endotracheal tubes to reduce microaspiration and intubation-related pneumonia: a systematic review of laboratory and clinical studies,” Critical Care (London, England), vol. 20, no. 1, p. 203, 2016.

B. Maertens, K. Blot, and S. Blot, “Prevention of ventilator-associated and early postoperative pneumonia through tapered endotracheal tube cuffs,” Critical Care Medicine, vol. 46, no. 2, pp. 316–323, 2018.

S. Nseir, L. Lorente, M. Ferrer, A. Rouze, O. Gonzalez, and G. L. Bassi, “Continuous control of tracheal cuff pressure for VAP prevention: a collaborative meta-analysis of individual participant data,” Annals of Intensive Care, vol. 5, no. 1, p. 43, 2015.

D. A. Caroff, L. Li, J. Muscedere, and M. Klompas, “Subglottic secretion drainage and objective outcomes: a systematic review and meta-analysis,” Critical Care Medicine, vol. 44, no. 4, pp. 830–840, 2016.

S. Galwankar, M. Vyas, D. Desai, and Z. F. Udwadia, “Hepatic sarcoidosis responding to chloroquine as steroid-sparing drug,” Indian Journal of Gastroenterology, vol. 18, no. 4, pp. 177-178, 1999.

N. Saito, T. Yagi, Y. Hara, H. Matsumoto, and K. Mashiko, “Endotracheal tube with tapered-type cuff for preventing ventilator-associated pneumonia: a randomized clinical trial,” Critical Care, vol. 17, p. P153, 2013.

F. Philippart, S. Gaudry, L. Quinquis et al., “Randomized intubation with polyurethane or conical cuffs to prevent pneumonia in ventilated patients,” American Journal of Respiratory and Critical Care Medicine, vol. 191, no. 6, pp. 637–645, 2015.

A. Monsel, Q. Lu, M. Le Corre et al., “Tapered-cuff endotracheal tube does not prevent early postoperative pneumonia compared with spherical-cuff endotracheal tube after major vascular surgery,” Anesthesiology, vol. 124, no. 5, pp. 1041–1052, 2016.

A. Mahmoodpoor, H. Hamishehkar, M. Hamidi et al., “A prospective randomized trial of tapered-cuff endotracheal tubes with intermittent subglottic suctioning in preventing ventilator-associated pneumonia in critically ill patients,” Journal of Critical Care, vol. 38, pp. 152–156, 2017.