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Table 3 Summary of clinical studies

From: The value of polyurethane-cuffed endotracheal tubes to reduce microaspiration and intubation-related pneumonia: a systematic review of laboratory and clinical studies

Author, year Materials tested Study design Pcuff Outcomes Main results
Lucangelo, 2008 [14] • PU-cuffed ETT, cylindrical shape (Mallinckrodt SealGuard, Mallinckrodt Medical, Cornamady, Anthlone County, Ireland)
• PVC-cuffed ETT, spindle-like shape (Mallinckrodt Hi-Lo, Mallinckrodt Medical, Cornamady, Anthlone County, Ireland)
• RCT
• 2 groups of 20 ICU patients requiring immediate orotracheal intubation and mechanical ventilation because of deterioration of consciousness (GCS score ≤8)
• Ventilatory settings: VC ventilation with VT 8–9 ml/kg and respiratory rate to maintain normocapnia, and PEEP (5 cmH2O)
• 5 h postintubation, PEEP was removed
• Oral and tracheal secretions were not aspirated during experiment
• 30 cmH2O • Controlled with aneroid manometer • Evans blue (1 ml) diluted in normal saline (1 ml)
• Bronchoscopic evaluation to detect blue dye in trachea at 1 h and 5 h postintubation (with PEEP) and hourly thereafter until 12 h postintubation (without PEEP)
• As soon as blue spot was seen on trachea caudal to ETT tip, experiment was finished
• 5 h postintubation, leakage observed in 2 patients in PVC group
• At 6th hour (1 h after PEEP removal), leakage observed in all patients in PVC group
• In the PU group, first leakage occurred after 8 h; at end of experiment (12th hour), fluid leakage absent in 3 patients
• Difference between the 2 groups (log-rank test on Kaplan-Meier survival curves) was statistically significant (p < 0.001)
Poelaert, 2008 [30] • PU-cuffed ETT, cylindrical shape (SealGuard, Covidien, Mansfield, Mass, USA)
• PVC-cuffed ETT, cylindrical shape (standard Mallinckrodt, Mallinckrodt Inc. Hazelwood, Mo, USA)
• Female patients: ID 8 mm
• Male patients: ID 9 mm
• RCT, single-blind
• 2 groups of 67 patients scheduled for cardiac surgery
• Intraoperative antibiotic prophylaxis with cefazolin 2 g 3 times daily for 24 h
• 20–26 cmH2O
• Controlled immediately after intubation, at closure of sternum, on arrival at ICU, and every 4 h during postoperative course
• Early postoperative pneumonia (until 7 days postoperatively)
• Nosocomial pneumonia was defined as all of the following:
 - New/evolving infiltrate on chest x-ray
 - Temperature > 38.2 °C
 - Leukocytosis (>12000 cells/mm3)
 - Presence of purulent sputum/endotracheal aspirate
 - Increase in C-reactive protein for 2 consecutive postoperative days
 - Deterioration in PaO2/FiO2 ratio ≥20 %
• Diagnosis: assessor blinded
• Rate of postoperative pneumonia in PU group significantly lower than PVC group (23 % vs. 42 %; p = 0.026)
• In multivariate regression analysis, use of PU-cuffed ETTs appeared to be protective for early postoperative pneumonia (OR 0.31, 95 % CI 0.13–0.77)
Nseir, 2010 [40] • PU-cuffed ETT, cylindrical shape (MICROCUFF, Kimberly-Clark, Zaventem, Belgium)
• PVC-cuffed ETT, cylindrical shape (Mallinckrodt Hi-Lo Lanz, Mallinckrodt Medical, Athlone, Ireland)
• Prospective, observational trial in ICU patients
• PVC group (patients included in first 6 months of study, n = 26); PVC group (patients included in second period of 6 months, n = 22)
• Patients observed during 24 h with continuous monitoring of Pcuff
• After 24 h, tracheal suctioning to obtain aspirate sample for pepsin measurement
• Pepsin levels considered positive at 200 ng/ml
• 25 cmH2O
• Manually adjusted every 8 h
• Pepsin in tracheal secretions (ng/ml) used as proxy for microaspiration of gastric contents
• Recorded 24 h postintubation
• No difference in Pcuff variation observed between groups
• Pepsin levels lower among patients with PU-cuffed ETTs (217 ± 126 ng/ml) than in PVC group (408 ± 282 ng/ml)
• Pepsin levels >200 ng/ml more common in PVC group (69 % vs. 27 %; p = 0.008)
• Pepsin levels >300 ng/ml more common in PVC group (61 % vs. 22 %; p = 0.009)
Miller, 2011 [32] • PU-cuffed ETT, cylindrical shape (MICROCUFF, Kimberly-Clark Corporation, Roswell, GA, USA)
• PVC-cuffed ETT, cylindrical shape (conventional type)
• Before-after study with interrupted time-series analysis
• 1 hospital, 5 ICUs
• Retrospective comparison of VAP rates in respective periods
• 1 year of observation with PVC-cuffed tubes before intervention
• 1 year of observation with PU-cuffed ETTs
• 3 months postintervention observation (return to conventional PVC-cuffed ETTs)
Not reported • VAP rates expressed per 1000 ventilation days
• VAP diagnosed on basis of clinical or microbiologic criteria, based on CDC’s National Healthcare Safety Network standard definition [29]
• Baseline year of observation (PVC-cuffed ETT): 37 VAP episodes (5.3/1000 ventilation days)
• Intervention year (PU-cuffed ETT): 21 VAP episodes (2.8/1000 ventilation days) (p = 0.0138)
• After return to PVC-cuffed ETTs, 6 episodes in 3 months (3.5/1000 ventilation days)
• Incidence risk ratio of VAP during intervention year 0.57 (95 % CI 0.34–0.96)
Philippart, 2015 [31] • PU-cuffed ETT, cylindrical shape (MICROCUFF, Kimberly-Clark, Irving, Tx, USA)
• PVC-cuffed ETT, cylindrical shape (Hi-Lo, Covidien, Dublin, Ireland)
• PU-cuffed ETT, conical shape (SealGuard, Covidien, Dublin, Ireland)
• PVC-cuffed ETT, conical shape (TaperGuard, Covidien, Dublin, Ireland)
• ID 7.5 or 8 mm
• Multicenter RCT, 4 study arms
• PU cylindrical group (n = 123)
• PVC cylindrical group (n = 129)
• PU conical group (n = 153)
• PVC conical group (n = 129) At study inclusion, no important differences between groups were observed
• 25–30 cmH2O
• Manually controlled with manometer every 6 h
• Airway management standardized across study sites
• Primary endpoint: bacterial colonization of the trachea (103 CFU/ml) at days 1, 2, 3, 7
• Secondary endpoint: cumulative VAP rate during ICU stay, defined on basis of clinical, biological and radiological patterns [41]; bacterial cultures sampled in all patients suspected of having VAP and confirmed if quantitative culture was at least 104 CFU/ml
• No differences in tracheal colonization (at >103, >104, >105, or >106 CFU/ml) were observed 48 h postintubation (p > 0.05, p value indicates difference across 4 groups)
• VAP rate between PU cylindrical and PVC cylindrical group not different (resp. 17.1 % vs. 10.8 %; p = 0.202)
• VAP rate between PU conical and PVC conical group not different (respectively 16.3 % vs. 13.2 %; p = 0.505)
• No difference in VAP rate observed when both PU groups and both PVC groups were pooled (respectively 16.6 % vs. 12.0 %; p = 0.140)
  1. Abbreviations: PU polyurethane, PVC polyvinyl chloride, RCT randomized controlled trial, GCS Glasgow Coma Scale, VC volume-controlled, V T tidal volume, PEEP positive end-expiratory pressure, ID internal diameter, VAP ventilator-associated pneumonia, CDC Centers for Disease Control and Prevention, PaO 2 /FiO 2 ratio of arterial oxygen partial pressure to fractional inspired oxygen
  2. Study arms or other aspects of the study that have no relationship with the outcome of interest of this review are not included in the summary of the individual studies