The impact of hospital-wide use of a tapered-cuff endotracheal tube on the incidence of ventilator-associated pneumonia

The effect of different inflating volume on the measurement accuracy of the modified cuff pressure measurement method

To evaluate the effect of different inflation volume on the measurement accuracy of the modified cuff pressure measurement method in different shapes of cuffs, so as to provide reference for the correct monitoring of cuff pressure in clinic. In vitro study: The traditional cuff pressure measurement method (the cuff pressure gauge before measurement shows 0 cm H₂O) and the modified cuff pressure measurement method (the cuff pressure before measurement shows 25 cm H₂O, 28 cm H₂O, 30 cm H₂O or 32 cm H₂O) were used to measure cylindrical and tapered cuffs, and the effect of different inflation volume on cuff pressure was analyzed statistically. Clinical study: patients with the artificial airway established by orotracheal intubation or tracheotomy in Neuro-ICU were prospectively selected as subjects, and the measurement procedure was the same as in vitro study. In vitro study showed that the pressure loss values of cylindrical cuff and tapered cuff using the traditional cuff pressure measurement method were (3.75 ± 0.31) cm H₂O and (4.92 ± 0.44) cm H₂O, respectively, and clinical study showed that the pressure loss values were (5.07 ± 0.83) cm H₂O and (5.17 ± 0.93) cm H₂O, respectively. The actual measured values measured by the traditional cuff pressure measurement method of the two cuff shapes were compared with the corrected target value of 28 cm H₂O, and the differences were statistically significant (P < 0.000). Both in vitro and clinical study had shown that all differences between the actual measured value and the corrected target value using the modified cuff pressure measurement method (measured with 25 cm H₂O, 30 cm H₂O, 32 cm H₂O) were statistically significant (P < 0.000), and the range of overall differences was (0-1.23 ± 0.25) cm H₂O. In vitro study had shown that the pressure variation coefficient (CV) of the tapered cuff was greater than that of the cylindrical cuff, and the difference was statistically significant (3.08 ± 0.25 VS 2.41 ± 0.21, P < 0.000). The traditional cuff pressure measurement method can directly lead to the cuff pressure drop, which is easy to cause the leakage of secretions on the cuffs and the misjudgment of the cuff pressure by medical personnel. However, the modified cuff pressure measurement method can effectively reduce cuff pressure loss, and taking the actual cuff pressure value as the inflation volume is the highest measurement accuracy.The tapered cuff is more susceptible to air volume, so it is necessary to pay attention to its measurement and correction in clinical practice.

Implementation of the TaperGuard™ endotracheal tube in an unselected surgical population to reduce postoperative pneumonia

BACKGROUND

Endotracheal tube (ETT) designs to decrease the risk of ventilator associated pneumonia (VAP) include supraglottic suctioning, and/or modifications of the cuff shape. The TaperGuard™ ETT has a tapered, polyvinylchloride cuff designed to reduce microaspiration around channels that form with a standard barrel-shaped cuff. We compared risk of postoperative pneumonia using the TaperGuard™ ETT and the standard ETT in surgical patients requiring general anesthesia with endotracheal intubation.

METHODS

We used an interrupted time-series design to compare endotracheal intubation using the TaperGuard™ ETT (intervention cohort), and a historic cohort using the standard ETT (baseline cohort), among surgical patients requiring hospital admission. We compared the incidence of postoperative pneumonia in the intervention and baseline cohorts. Data were collected from the electronic health record and linked to patient-level data from National Surgical Quality Improvement Project. Additionally, we performed secondary analyses in a subgroup of patients at high risk of postoperative pneumonia.

RESULTS

15,388 subjects were included; 6351 in the intervention cohort and 9037 in the baseline cohort. There was no significant difference in the incidence of postoperative pneumonia between the intervention cohort (1.62%) and the baseline cohort (1.79%). The unadjusted odds ratio (OR) of postoperative pneumonia was 0.90 (95% CI: 0.70, 1.16; p = 0.423) and the OR adjusted for patient characteristics and potential confounders was 0.90 (95% CI: 0.69, 1.19; p = 0.469), comparing the intervention and baseline cohorts. There was no a priori selected subgroup of patients for whom the use of the TaperGuard™ ETT was associated with decreased odds of postoperative pneumonia relative to the standard ETT. Hospital mortality was higher in the intervention cohort (1.5%) compared with the baseline cohort (1.0%; OR 1.46, 95% CI: 1.09, 1.95; p = 0.010).

CONCLUSIONS

The broad implementation of the use of the TaperGuard™ ETT for intubation of surgical patients was not associated with a reduction in the risk of postoperative pneumonia. In the setting of a low underlying postoperative pneumonia risk and the use of recommended preventative VAP bundles, further risk reduction may not be achievable by simply modifying the ETT cuff design in unselected or high-risk populations undergoing inpatient surgery.

TRIAL REGISTRATION

ClinicalTrials.gov, ID NCT02450929 .

Pathogenesis-Targeted Preventive Strategies for Multidrug Resistant Ventilator-Associated Pneumonia: A Narrative Review

Ventilator-associated pneumonia (VAP) is the most common hospital-acquired infection in the intensive care unit (ICU), accounting for relevant morbidity and mortality among critically ill patients, especially when caused by multidrug resistant (MDR) organisms. The rising problem of MDR etiologies, which has led to a reduction in treatment options, have increased clinician’s attention to the employment of effective prevention strategies. In this narrative review we summarized the evidence resulting from 27 original articles that were identified through a systematic database search of the last 15 years, focusing on several pathogenesis-targeted strategies which could help preventing MDR-VAP. Oral hygiene with Chlorhexidine (CHX), CHX body washing, selective oral decontamination (SOD) and/or digestive decontamination (SDD), multiple decontamination regimens, probiotics, subglottic secretions drainage (SSD), special cuff material and shape, silver-coated endotracheal tubes (ETTs), universal use of gloves and contact isolation, alcohol-based hand gel, vaporized hydrogen peroxide, and bundles of care have been addressed. The most convincing evidence came from interventions directly addressed against the key factors of MDR-VAP pathogenesis, especially when they are jointly implemented into bundles. Further research, however, is warranted to identify the most effective combination.

Bias in Before-After Studies: Narrative Overview for Anesthesiologists

Before-after study designs are effective research tools and in some cases, have changed practice. These designs, however, are inherently susceptible to bias (ie, systematic errors) that are sometimes subtle but can invalidate their conclusions. This overview provides examples of before-after studies relevant to anesthesiologists to illustrate potential sources of bias, including selection/assignment, history, regression to the mean, test-retest, maturation, observer, retrospective, Hawthorne, instrumentation, attrition, and reporting/publication bias. Mitigating strategies include using a control group, blinding, matching before and after cohorts, minimizing the time lag between cohorts, using prospective data collection with consistent measuring/reporting criteria, time series data collection, and/or alternative study designs, when possible. Improved reporting with enforcement of the Enhancing Quality and Transparency of Health Research (EQUATOR) checklists will serve to increase transparency and aid in interpretation. By highlighting the potential types of bias and strategies to improve transparency and mitigate flaws, this overview aims to better equip anesthesiologists in designing and/or critically appraising before-after studies.

Prevention of Ventilator-Associated and Early Postoperative Pneumonia Through Tapered Endotracheal Tube Cuffs: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

Microaspiration of subglottic secretions is considered a major pathogenic mechanism of hospital-acquired pneumonia, either early postoperative or ventilator-associated pneumonia. Tapered endotracheal tube cuffs have been proposed to provide a better seal of the extraluminal airway, thereby preventing microaspiration and possibly hospital-acquired pneumonia. We performed a systematic review and meta-analysis to assess the value of endotracheal tubes with tapered cuffs in the prevention of hospital-acquired pneumonia.

DATA SOURCES

A systematic search of MEDLINE, EMBASE, CENTRAL/CCTR, ClinicalTrials.gov, and ICTRP was conducted up to March 2017.

STUDY SELECTION

Eligible trials were randomized controlled clinical trials comparing the impact of tapered cuffs versus standard cuffs on hospital-acquired pneumonia.

DATA EXTRACTION

Random-effects meta-analysis calculated odds ratio and 95% CI for hospital-acquired pneumonia occurrence rate between groups. Secondary outcome measures included mortality, duration of mechanical ventilation, length of hospital and ICU stay, and cuff underinflation.

DATA SYNTHESIS

Six randomized controlled clinical trials with 1,324 patients from intensive care and postoperative wards were included. Only two studies concomitantly applied subglottic secretion drainage, and no trial performed continuous cuff pressure monitoring. No significant difference in hospital-acquired pneumonia incidence per patient was found when tapered cuffs were compared with standard cuffs (odds ratio, 0.97; 95% CI, [0.73-1.28]; p = 0.81). There were likewise no differences in secondary outcomes.

CONCLUSIONS

Application of tapered endotracheal tube cuffs did not reduce hospital-acquired pneumonia incidence among ICU and postoperative patients. Further research should examine the impact of concomitant use of tapered cuffs with continuous cuff pressure monitoring and subglottic secretion drainage.

Airway Devices in Ventilator-Associated Pneumonia Pathogenesis and Prevention

Airway devices play a major role in the pathogenesis of microaspiration of contaminated oropharyngeal and gastric secretions, tracheobronchial colonization, and ventilator-associated pneumonia (VAP) occurrence. Subglottic secretion drainage is an effective measure for VAP prevention, and no routine change of ventilator circuit. Continuous control of cuff pressure, silver-coated tracheal tubes, low-volume low-pressure tracheal tubes, and the mucus shaver are promising devices that should be further evaluated by large randomized controlled trials. Polyurethane-cuffed, conical-shaped cuff, and closed tracheal suctioning system are not effective and should not be used for VAP prevention.

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

Background

Microaspiration of secretions around the tracheal cuff is a multifactorial process. Tracheal cuff shape might take a major part in its occurrence. The rationale for producing a taper-shaped cuff is 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.

Objectives

The primary objective of this meta-analysis was to compare ventilator-associated pneumonia (VAP) between tapered-cuff intubation and conventional-cuff intubation. The secondary objective was to compare intensive care unit (ICU) mortality between tapered-cuff intubation and conventional-cuff intubation.

Methods

We searched the Cochrane Library, Embase, MEDLINE database through the PubMed search engine, and CINAHL from inception to April 2018. Randomized trials comparing VAP and ICU mortality between tapered-cuff intubation and conventional-cuff intubation in intubated adults were included. Two review authors assessed study quality and abstracted databasing on prespecified criteria independently.

Results

We pooled summary estimates from 5 trials evaluating tapered-cuff involving 774 participants. Compared to VAP, no statistically significant difference was observed between the tapered-cuff and conventional-cuff groups (OR 0.82, CI 0.61-1.12, z = 1.24, and p=0.21). No statistically significant difference was observed between the tapered-cuff and conventional-cuff groups with ICU mortality (OR 0.77, CI 0.55-1.08, z = 1.49, and p=0.14).

Conclusions

In this meta-analysis, the tapered-cuff tracheal tube may not be superior to the standard-cuff tracheal tube in reducing VAP and ICU mortality.

Orotracheal tube as a risk factor for lower respiratory tract infection: preliminary data from a randomised trial

PURPOSE

The aim of the study was to investigate whether polyurethane (PU) endotracheal tubes, continuous measurements of cuff pressure and aspiration of the subglottic space as a bundle of parameters could reduce patients' risk for developing ventilator associated pneumonia (VAP).

METHODS

Two groups of patients that differed only in terms of endotracheal tubes and intubation intervention were compared. Group A was ventilated using PU tubes a with conical cuff; they also had continuous cuff pressure measurement and continuous subglottic aspiration. Group B was ventilated using PVC tubes with a cylindrical cuff; the patients underwent intermittent cuff pressure measurement and intermittent subglottic aspiration.

RESULTS

Seven patients in group A (13.2%) and 18 in group B (36.0%) out of 103 were diagnosed with VAP. VAP patients were in general older, stayed longer in the ICU and were ventilated significantly longer compared with the patients with no VAP. Eight more patients in group B died compared with group A. Moreover, subjects in group A survived longer. Patient age, hours on mechanical ventilation, and days on an ICU were all positively associated with the occurrence of VAP.

CONCLUSIONS

Prevention parameters in ventilation (PU cuff, conical cuff, continuous subglottic drainage and continuous cuff pressure measurement) could prevent the incidence of VAP in ICU patients.

Modification of Tracheal Cuff Shape and Continuous Cuff Pressure Control to Prevent Microaspiration in an Ex Vivo Pig Tracheal Two-Lung Model

OBJECTIVES

Microaspiration of subglottic secretions plays a pivotal role in ventilator-associated pneumonia. Impact of endotracheal tube cuff material and shape on tracheal sealing performance remains debated. The primary objective was to compare the tracheal sealing performance of polyvinyl chloride tapered, cylindrical and spherical cuffs. Secondary objectives were to determine the impact of continuous cuff pressure control on sealing performance and pressure variability.

DESIGN

Prospective randomized ex vivo animal study.

SETTING

French research laboratory.

SUBJECTS

Seventy-two ex vivo pig tracheal two-lung blocks.

INTERVENTIONS

Blocks were randomly intubated with cylindrical (n = 26), tapered (n = 24), or spherical (n = 22) polyvinyl chloride endotracheal tube cuffs. Two milliliter of methylene blue were instilled above the cuff to quantify microaspirations, and lungs were ventilated for 2 hours. Continuous cuff pressure control was implemented in 33 blocks.

MEASUREMENTS AND MAIN RESULTS

Cuff pressures were continuously recorded, and after 2 hours, a microaspiration score was calculated. Tapered cuffs improved cuff sealing performance compared with spherical cuffs with or without continuous cuff pressure control. Compared with spherical cuffs, tapered cuffs reduced the microaspiration score without and with continuous pressure control by 65% and 72%, respectively. Continuous cuff pressure control did not impact sealing performance. Tapered cuffs generated higher cuff pressures and increased the time spent with overinflation compared with spherical cuffs (median [interquartile range], 77.9% [0-99.8] vs. 0% [0-0.5]; p = 0.03). Continuous cuff pressure control reduced the variability of tapered and spherical cuffs likewise the time spent with overinflation of tapered and cylindrical cuffs.

CONCLUSIONS

Polyvinyl chloride tapered cuffs sealing enhanced performance at the cost of an increase in cuff pressure and in time spent with overinflation. Continuous cuff pressure control reduced the variability and normalized cuff pressures without impacting sealing performance.

Impact of tapered-cuff tracheal tube on microaspiration of gastric contents in intubated critically ill patients: a multicenter cluster-randomized cross-over controlled trial

PURPOSE

Studies on the impact of tapered-cuff tracheal tubes on rates of microaspiration and ventilator-associated pneumonia (VAP) in intubated patients have reported conflicting results. The aim of this study was to determine the influence of this shape of tracheal cuff on abundant microaspiration of gastric contents in critically ill patients.

METHODS

All patients intubated in the intensive care unit (ICU) and requiring mechanical ventilation for at least 48 h were eligible for this multicenter cluster-randomized controlled cross-over open-label study. The primary outcome was abundant microaspiration of gastric contents, defined by the presence of pepsin at significant level in >30% of tracheal aspirates. Quantitative measurement of pepsin and salivary amylase was performed in all tracheal aspirates during the 48 h following enrollment.

RESULTS

A total of 326 patients were enrolled in the ten participating ICUs (162 in the PVC tapered-cuff group and 164 in the standard-cuff group). Patient characteristics were similar in the two study groups. The proportion of patients with abundant microaspiration of gastric contents was 53.5% in the tapered-cuff and 51.0% in the standard-cuff group (odds ratio 1.14, 95% CI 0.72-1.82). While abundant microaspiration of oropharyngeal secretions was not significantly different (77.4 vs 68.6%, p = 0.095), the proportion of patients with tracheobronchial colonization was significantly lower (29.6 vs 43.3%, p = 0.01) in the tapered-cuff than in the standard-cuff group. No significant difference between the two groups was found for other secondary outcomes, including ventilator-associated events and VAP.

CONCLUSIONS

This trial showed no significant impact of tapered-cuff tracheal tubes on abundant microaspiration of gastric contents.

TRIAL REGISTRATION

ClinicalTrials.gov, number NCT01948635.

[Ventilator-associated pneumonia (VAP) : A risk already at the time of anesthetic induction]

BACKGROUND

Ventilator-associated pneumonia (VAP) is one of the most common and preventable infections in mechanically ventilated patients. It is associated with a high mortality rate. To prevent VAP, various strategies address this issue using "VAP-bundles", which are implemented in many intensive care units. The risk of acquiring VAP starts with the induction of anesthesia, strictly speaking at the time of intubation. This article considers measures to prevent VAP during general anesthesia in adult patients (>18 years). Procedures beyond standard hygienic precautions for VAP prevention are reviewed.

METHODS

A literature search in different databases (PubMed, Cochrane, Ovid und CINAHL) over the last five years.

RESULTS

Beyond standard hygienic precautions, microaspiration should be avoided to prevent VAP. During mechanical ventilation at least 5 cm H₂O PEEP is advised. Continuous monitoring and adjustment of cuff pressure is necessary. All patients mechanically ventilated after general anesthesia for more than 24 h should be intubated with an ETT with a port for subglottic suctioning.

Tapered-cuff Endotracheal Tube Does Not Prevent Early Postoperative Pneumonia Compared with Spherical-cuff Endotracheal Tube after Major Vascular Surgery

Background

Patients undergoing major vascular surgery often develop postoperative pneumonia that impacts their outcomes. Conflicting data exist concerning the potential benefit of tapered-shaped cuffs on tracheal sealing. The primary objective of this study was to assess the efficiency of a polyvinyl chloride tapered-cuff endotracheal tube at reducing the postoperative pneumonia rate after major vascular surgery. Secondary objectives were to determine its impact on microaspiration, ventilator-associated pneumonia rate, and inner cuff pressure.

Methods

This prospective randomized controlled study included 109 patients who were randomly assigned to receive either spherical- (standard cuff) or taper-shaped (tapered cuff) endotracheal tubes inserted after anesthesia induction and then admitted to the intensive care unit after major vascular surgery. Cuff pressure was continuously recorded over 5 h. Pepsin and α-amylase concentrations in tracheal aspirates were quantified on postoperative days 1 and 2. The primary outcome was the early postoperative pneumonia frequency.

Results

Comparing the tapered-cuff with standard-cuff group, respectively, postoperative pneumonia rates were comparable (42 vs. 44%, P = 0.87) and the percentage (interquartile range) of cuff-pressure time with overinflation was significantly higher (16.1% [1.5 to 50] vs. 0.6% [0 to 8.3], P = 0.01), with a 2.5-fold higher coefficient of variation (20.2 [10.6 to 29.4] vs. 7.6 [6.2 to 10.2], P &lt; 0.001). Although microaspiration frequencies were high, they did not differ between groups.

Conclusion

For major vascular surgery patients, polyvinyl chloride tapered-cuff endotracheal tubes with intermittent cuff-pressure control did not lower the early postoperative pneumonia frequency and did not prevent microaspiration.