Ventilator-associated pneumonia (VAP) occurs after starting mechanical ventilation. Prevalence of VAP and its mortality was 11% and 78.9%, respectively [
The primary mechanism of VAP pathogenesis is colonized oropharyngeal secretion aspiration [
We carried out a literature search using the Cochrane Library, Embase, MEDLINE database through the PubMed search engine, and CINAHL from inception to April 2018. No restrictions were placed on the language of the publications. The following medical subject headings (MeSH) were searched: randomized controlled trial, tapered cuff, conical cuff, cylindrical cuff, spherical-shaped cuff, conventional cuff, standard cuff, and ventilator-associated pneumonia. Since our study was a meta-analysis, the approval of the ethics committee was not available.
We included randomized controlled trials (RCTs) that involved the use of a tapered cuff and a conventional cuff for intubation. Articles were included if they were in English and were full-text articles reporting original research. We considered for inclusion of all adults. If the primary outcome measures were not VAP, then these studies were excluded. Editorials, letters, and retrospective studies were excluded. Any disagreement about whether the trials meet the inclusion or exclusion criteria between the two reviews was resolved by discussing with a third reviewer. We resolved the problem through the agreement by two reviewers.
Two reviewers independently evaluated the included studies and extracted data into RevMan (Review Manager: Cochran handbook for systematic reviews). Any disagreement was resolved by discussion with a third reviewer. If further data were required, communication through e-mail would be carried out with the authors. The following items were extracted from the tapered-cuff group and the conventional-cuff group: first author, publication year, country, study design, kind of intensive care unit (ICU), sample size, endotracheal tube type, internal diameter of the tracheal tube, cuff pressure, PEEP, VAP assessment, and duration of follow-up.
The primary endpoint of this meta-analysis VAP was defined based on clinical, radiological, and laboratory findings. The secondary outcomes were ICU mortality.
All studies were assessed with the Jadad scale scoring system [
For each included study, odds ratio (OR) and 95% confidence interval (CI) were calculated for dichotomous outcomes. Statistical heterogeneity was assessed using the
A total of 127 potentially related articles were preliminarily screened on the search of the database. Eighteen articles were excluded for a duplicate. After reading the abstracts, 76 articles were excluded, whereas 33 articles were excluded for full-text scrutiny. Finally, the search strategy identified that a total of 5 published RCTs were included in the final analysis [
The graph showing a flow diagram of detailed search and exclusion criteria.
We identified 5 RCTs. All selected studies in our meta-analysis were published from 2013 to 2017. The follow-up period ranged from 1 week to 2 months after using ventilation. The selected study characteristics are summarized in Table
Characteristics of the five randomized controlled trials included in the meta-analysis.
Author, year | Design | Country | Kind of ICU | No. of patients | Endotracheal tube type | Internal diameter of tracheal tube | Cuff pressure | PEEP | VAP assessment | Duration of follow-up | Quality assessment |
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Jaillette et al. 2017 [ |
Multicenter, randomized, cross-over, open-label | France | Mixed ICU | Tapered ( |
PVC tapered-cuffs (TaperGuard; Covidien, Athlone, Ireland); PVC standard cuffs (Hi-Lo; Covidien, Athlone, Ireland) | 7.5 and 8 mm | Tapered 29 (26–30) cmH2O, conventional 28 (25–30)cmH2O | >5 cmH2O | Using clinical, radiographic, and microbiological criteria. | Until 28 days or ICU discharge | Good |
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Mahmoodpoor et al., 2013, [ |
Randomized, single-blind | Iran | Mixed ICU | Tapered ( |
TaperGuard tubes (PU, cone-/taper-shaped cuffs with subglottic suction ports); SealGuard tubes (PU, cylindrical-/barrel-shaped cuffs with subglottic secretion suction ports). | Male 8.0 to 8.5 mm, female 7.0 to 7.5 mm. | Tapered (24.07 ± 0.48 cmH2O), conventional (24.10 ± 0.49 cmH2O) | 5 cmH2O | VAP was defined based on clinical, radiological, and laboratory findings based on CPIS. | Until ICU discharge | Good |
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Mahmoodpoor et al., 2017, [ |
Randomized, single-blind | Iran | Surgical ICU | Tapered ( |
TaperGuard tubes; conventional high-volume low-pressure endotracheal tubes. | Male 8.0 to 8.5 mm, female 7.0 to 7.5 mm. | Tapered (23.7 ± 2.3 cmH2O), conventional (27.0 ± 4.7 cmH2O) | 5 cmH2O | Suspected by clinical infection pulmonary score (CPIS) | Until ICU discharge | Good |
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Monsel et al., 2016, [ |
Randomized, single-blind | France | Surgical ICU | Tapered ( |
TaperGuard (Covidien, Ireland); standard cuffs with high contour Brandt endotracheal tubes incorporating a polyvinyl chloride spherical-shaped cuff (Mallinckrodt Medical,USA) | The endotracheal tube size was chosen according to professional guidelines. | 25 cmH2O | Tapered 5.6 (5.0–6.3) cmH2O, conventional 5.0 (5.0–6.0) cmH2O | VAP was confirmed when Johanson criteria were associated with a significant concentration of bacteria isolated from lower respiratory tract. | Lengths of mechanical ventilation and ICU stay. | Good |
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Philippart et al., 2015, [ |
Randomized, multicenter, open-lablel | France and Tunisia | Medical surgical ICUs | Tapered ( |
TaperGuard (Covidien, Ireland); cylindrical (Hi-Lo; Covidien, Dublin, Ireland) | The patients received tracheal intubation with a 7.5–8.0 mm diameter. | The cuff was inflated to a pressure of 25–30 cmH2O | ≥5 cmH2O | VAP was confirmed when the quantitative culture was at least 104 cfu/ml in a bronchoalveolar lavage or 105 dfu/ml in a quantitative tracheal aspirate. | Until ICU discharge | Good |
The detailed risk of bias abuts the methodological quality of the included studies that are elaborated and summarized, respectively, in Figures
The graph showing a risk of bias graph.
The graph showing a risk of bias summary.
The primary endpoint “VAP” was reported in all five studies. A total of 384 patients in the tapered-cuff group and 390 patients in the conventional-cuff group were available to compare VAP. No statistically significant difference was observed between the tapered-cuff and conventional-cuff groups (OR 0.82, CI 0.61–1.12,
The graph showing a forest plot of relative risk with confidence interval for VAP.
The secondary endpoint “ICU mortality” was reported in all four studies. A total of 384 patients in the tapered-cuff group and 391 patients in the conventional-cuff group were available to compare ICU mortality. No statistically significant difference was observed between the tapered-cuff and conventional-cuff groups (OR 0.77, CI 0.55–1.08,
The graph showing a forest plot of relative risk with confidence interval for ICU mortality.
Our study found that tapered-cuff tracheal tube compared with a conventional-cuff tracheal tube did not reduce the VAP rate and ICU mortality.
We conducted this meta-analysis because the tracheal cuff is the crucial interface between the tube and the tracheal wall that may be responsible for the leakage of contaminated secretions, which lead to colonization and possibly to VAP. New cuffs were developed recently to reduce microaspiration of secretions around the cuff of the endotracheal tube. A tapered shape theoretically ensures that the cuff and trachea share the same diameter, thereby leading to smaller folds and improving tracheal sealing [
In our meta-analysis, we found that tapered-cuff tracheal tubes, compared with conventional-cuff tracheal tubes, did not reduce VAP. But an in vitro study and a clinical study found that using tapered-cuff tracheal tubes decreased leakage around the tracheal cuff compared with the conventional cuff [
The rationale for producing a taper-shaped cuff was established on the assumption that compared to a conventional cuff with a single fixed diameter, a continuum of minimum-to-maximum diameter sections might better fit the tracheal walls. However, compared with other spherical- or cylindrical-shaped cuffs, tapered cuffs had the lowest tracheal wall contact area [
Different risk factors lead to ICU mortality. The specific risk factors are associated with their underlying diseases and VAP. We know that VAP is the most important risk factor for ICU mortality. In our meta-analysis, there was no difference in VAP between the tapered-cuff group and the conventional-cuff group. We estimate that the microaspiration between the two groups has no difference. So the ICU mortality between the two groups has no difference.
The blinding of participants and personnel was high risk because blinding of ICU physicians was not feasible during intubation. However, we estimate this bias to be minor, as the primary endpoint VAP and the secondary endpoint ICU mortality were blindly evaluated by physicians.
The current meta-analysis has some limitations. First, some included studies used polyurethane cuffs while others used polyvinyl chloride cuffs. Although bench studies suggested that polyurethane tapered cuffs had no benefits for microaspiration reduction, whether the cuff material might impact tracheal sealing remains to be investigated further. Second, in the conventional groups, one included study used spherical cuffs while others used cylindrical cuffs. Given that spherical and cylindrical cuffs are used worldwide, with proven good performances, have been compared in multiple trials [
The tapered-cuff tracheal tube may not be superior to the standard-cuff tracheal tube in reducing VAP and ICU mortality.
Ventilator-associated pneumonia
Intensive care unit
Medical subject headings
Randomized controlled trials
Review Manager
Odds ratio
Confidence interval.
The authors declare that they have no conflicts of interest.