Polyvinyl Chloride Cuff Research Articles

Development of a Circumallergenic Guayule Latex Endotracheal Tube Cuff

Abstract Endotracheal tube (ETT) cuffs made from soft, hypoallergenic guayule latex placed outside existing polyvinyl chloride (PVC) cuffs were previously developed as an alternative to PVC cuffs alone. Although these outer cuffs do not cross-react with Type I latex allergy, they were made using conventional vulcanization chemicals which can cause adverse contact reactions. New outer cuffs have been made with guayule latex using a xanthate-based accelerant system designed to avoid contact reactions and create a perfect seal with the patient’s trachea. A standard formula was used for compounding, and concentrations of all components remained constant except for two hypoallergenic accelerants: diisopropyl xanthogen polysulphide (DIXP), added in concentrations of either 2.0 or 2.2 parts per hundred rubber (phr), and zinc diisononyl dithiocarbamate (ZDNC), added in concentrations of 0.6, 0.8, or 1.0 phr. Samples were dipped at dwell times of 5 or 15 s for thickness variation. Cured samples underwent tensile testing 14 days after creation. Benchtop leak tests were conducted using a standard PVC cuff with three simulated trachea sizes. Additional leak tests were performed using the guayule latex cuffs and a 20 mm inner diameter tube. A combination of 2.0 phr DIXP and 0.6 phr ZDNC resulted in the highest tensile strength in both thin and thick cuffs. The lowest modulus values occurred at 2.0 phr DIXP and 0.8 ZDNC for thinner samples and 2.2 phr DIXP and 1.0 phr ZDNC for thicker samples. The two-way ANOVA for the double cuff leak test revealed no significant effect of accelerant concentration on leakage rate (P = 0.5783). Finally, varying the size of the simulated trachea for the PVC cuffs revealed that larger tracheas had lower average leak rates. All guayule latex double cuffs prevented leakage consistently. The samples made using a combination of 2.0 phr DIXP and 0.6 phr ZDNC had the most ideal mechanical properties (softness, stretchiness, and strength) for the creation of a guayule latex ETT balloon cuff. The decreased leakage rate of the PVC cuff in the larger simulated tracheas was due to the increased room for cuff expansion, reducing the number of longitudinal folds.

Endotracheal tube cuff position in relationship to the walls of the trachea: A retrospective computed tomography-based analysis.

The use of cuffed endotracheal tubes (ETTs) has become the standard of care in pediatric practice. The rationale for the use of a cuffed ETT is to minimize pressure around the cricoid while providing an effective airway seal. However, safe care requires that the cuff lie distal to the cricoid ring following endotracheal intubation. The current study demonstrates the capability of computed tomography (CT) imaging in identifying the position of the cuff of the ETT in intubated patients. The study included patients ranging in age from 1 month to 10 years who underwent neck and chest CT imaging that required general anesthesia and endotracheal intubation. The location of the ETT and of the cuff within the airway was determined from axial CT images at three levels (proximal, middle, and distal). Anatomical orientations were tabulated, and percent chances of each orientation were determined for the ETT and the cuff. The study cohort included 42 patients ranging in age from 1 to 114 months. An ETT with a polyvinylchloride cuff was used in 24 patients, and an ETT with a polyurethane cuff was used in 18 patients. The ETT was located near the posterior wall of the trachea in approximately 24-38% of patients, being most likely to be centrally located at the proximal end and at its mid-portion. The middle part of the cuff was most likely to be positioned in the mid-portion of the trachea but tended to skew anteriorly at both the proximal and distal ends. This is the first study using CT imaging to identify the uniformity of cuff inflation within the trachea in children. With commonly used cuffed ETTs, cuff inflation and the final position of ETT cuff within the tracheal lumen were not uniform. Future investigations are needed to determine the reasons for this asymmetry and its clinical implications.

A bench study on the prevention of lung-to-lung aspiration with double-lumen endobronchial tubes and bronchial blockers

Effective lung isolation prevents lung-to-lung aspiration during thoracotomy for the management of hemoptysis. Double-lumen endobronchial tubes (DLT) and bronchial blockers are commonly used for lung separation during thoracic surgery. In this study, the fluid-sealing characteristics of the endobronchial cuffs of three different commercially available DLTs (Broncho-Cath with a polyvinylchloride cuff, Broncho-Cath with a polyurethane cuff, and Human Broncho with a silicone cuff) and two different bronchial blockers (Arndt and Coopdech bronchial blockers) were evaluated using a benchtop model. The lateral decubitus position for the surgical management of bleeding from the right lung was simulated. The artificial tracheobronchial tree was placed horizontally, with the left bronchus in the dependent position and the right bronchus in the non-dependent position. In the DLT experiments, the tracheobronchial tree was intubated with left-sided DLTs, and the endobronchial cuff was inflated to maintain the intracuff pressure at 25 cmH2O. In the experiments with bronchial blockers, each bronchial blocker was inserted into the right bronchus, and the endobronchial cuff was inflated to seal the main bronchus. A fluid leakage test around the endobronchial cuff was performed using three different types of DLT (size 35, 37, and 41 Fr, each) and two different types of bronchial blockers (9 Fr). The 5 mL of colored water was poured into the right bronchus to simulate the blood flow from the operative side, and the times to the first and 100% leakage around the endobronchial cuff were recorded. Each bronchial blocker showed significantly less leakage over time than the other DLTs (P < 0.05). Fluid was not fully leaked around the cuffs for 24 h with either bronchial blocker. The times to first and 100% leakage were not significantly different among different types of DLTs. The times to first and 100% leakage did not also differ among the three different sizes of each type DLT. There was no significant difference in the time to first leakage around the endobronchial cuffs between Arndt and Coopdech bronchial blockers. Bronchial blockers provided a more effective seal against lung-to-lung aspiration than DLTs in the lateral decubitus position for thoracotomy in the benchtop model.

Comparison of polyurethane tracheal tube cuffs and conventional polyvinyl chloride tube cuff for prevention of ventilator-associated pneumonia: A systematic review with meta-analysis.

Background:The aim of this meta-analysis with trial sequential analysis (TSA) was to evaluate the effect of a polyurethane (PU) tracheal tube cuff on the prevention of ventilator-associated pneumonia (VAP).Methods:We performed a systematic search using the MEDLINE database through PubMed, Cochrane Central Register of Controlled Trial, SCOPUS, and Web of Science.Randomized controlled trials comparing the incidence of VAP and clinically relevant outcomes between PU cuff tubes and polyvinyl chloride (PVC) cuff tubes in adult patients. Two authors independently extracted study details, patient characteristics, and clinical outcomes such as incidence of VAP, bacterial colonization of tracheal aspirate, duration of mechanical ventilation, ICU stay, and ICU mortality.Results:From 309 studies identified as potentially eligible, six studies with 1226 patients were included in this meta-analysis. All studies compared the incidence of VAP between PU cuffs and PVC cuffs. Use of a PU cuff was not associated with a reduction in VAP incidence (RR = 0.68; 95% CI, 0.45–1.03) with significant statistical heterogeneity (I2 = 65%). The quality of evidence was “very low.” According to the TSA, the actual sample size was only 15.8% of the target sample size, and the cumulative Z score did not cross the trial sequential monitoring boundary for benefit. No positive impact was reported for the other relevant outcomes for PU cuffs.Conclusions:The use of a PU cuff for mechanical ventilation did not prevent VAP. Further trials with a low risk of bias need to be performed.

Evaluation of audible leak versus pressure volume loop closure for polyvinyl chloride cuff and polyurethane microcuff in endotracheal tube inflated with air: a prospective randomized study.

Cuff pressure of endotracheal tube (ETT) must be high enough to seal the trachea, and must be low enough to allow adequate perfusion of tracheal mucosa. Compared with polyvinyl chloride (PVC) cuffed tubes, polyurethane cuffed tubes protect more efficiently. Different methods of ETT cuff pressure maintenance in practice have been reported. We planned to compare ETT cuff pressure using different techniques in PVC and polyurethane microcuff tubes in a prospective randomized study. Eighty surgical patients between 16–65 years belonging to American Society of Anesthesiologists physical status I–III, scheduled for orotracheal intubation under general anaesthesia, were included. All enrolled patients were randomized into four groups (n = 20 per group), followed by corresponding treatments, including intubation by PVC ETT or polyurethane microcuff ETT and cuff inflation by auscultation of audible leak or pressure volume loop. Amount of air required to inflate cuff was more in polyurethrane tube as compared to polyvinyl tube. While comparing the two methods of cuff inflation, less volume of air was required in pressure volume loop method. We concluded that PVC cuff tube and polyurethane microcuff tube both are safe tubes used in adult patients. However, when inflated using same technique polyurethane microcuff tubes required larger volume to inflate cuff. Further, pressure generated in polyurethane microcuff tubes in much lower than PVC tubes. The study was approved by the Institutional Ethics Committee of Pt B D Sharma, PGIMS, Rohtak (No. IEC/Th/18/Anst15) on January 20, 2018 and registered with Clinical Trials Registry-India (registration No. CTRI/2019/01/017170) on January 18, 2019.

Implementation of the TaperGuard\u2122 endotracheal tube in an unselected surgical population to reduce postoperative pneumonia

BackgroundEndotracheal 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.MethodsWe 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.Results15,388 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).ConclusionsThe 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 registrationClinicalTrials.gov, ID NCT02450929.

Prevention of Lung Bacterial Colonization With a Leak-Proof Endotracheal Tube Cuff: An Experimental Animal Study.

Endotracheal tubes with standard polyvinyl chloride cuffs create folds on inflation into the trachea, which lead to potential leakage of subglottic secretions into the lower airways and cause lung colonization and pneumonia. The use of a double-layer prototype leak-proof cuff has shown effective prevention of the fluid leakage across the cuff. We hypothesized that the use of such a leak-proof cuff could prevent lung bacterial colonization in vivo. To simulate patients in the ICU, 13 pigs were placed in the semirecumbent position, intubated, and mechanically ventilated for 72 h. Five animals were prospectively intubated with an endotracheal tube with a leak-proof cuff (leak-proof cuff group). Data from 8 animals previously intubated with an endotracheal tube with a standard polyvinyl chloride cuff (standard cuff group) were retrospectively analyzed. Leakage of tracheal secretions across the leak-proof cuff was tested by the macroscopic methylene blue evaluation. Arterial blood gas exchanges and microbiology were tested in all the pigs at necropsy. In the standard cuff group, all the pigs showed heavy bacterial colonization of the lungs after 72 h of mechanical ventilation, with an overall proportion of colonized lung lobes of 92% (44/48 lobes, 8/8 animals) compared with 27% (8/30 lobes, 5/5 animals) in the leak-proof cuff group (P < .001). These results were strengthened by the absence of methylene blue in the tracheal secretions below the leak-proof cuff. Furthermore, no hypoxemia was demonstrated in the pigs in the leak-proof cuff group after the 72-h experiment (PaO2 /FIO2 change from baseline, leak-proof cuff group vs standard cuff group; median difference 332, 95% CI 41-389 mm Hg; P = .030). A new leak-proof cuff for endotracheal intubation prevented macroscopic leakage of subglottic secretions along the airways. This mechanism led to the reduction of lung bacterial colonization, which could contribute to the prevention of hypoxemia in the pigs on mechanical ventilation while in the semirecumbent position.

A newly developed tracheal tube offering 'pressurised sealing' outperforms currently available tubes in preventing cuff leakage: A benchtop study.

No currently used tracheal tube offers full protection against aspiration of oropharyngeal secretions into the lower airways. We developed a tracheal tube equipped with two polyvinylchloride (PVC) cuffs with a supplementary port opening between the cuffs through which a continuous positive pressure of 5 cmH2O is provided [double-cuffed PVC (PVCdc)]. We compared this PVCdc with four different cuff types (cylindrical PVC, conical PVC, cylindrical polyurethane and conical polyurethane). A comparison study using an in-vitro benchtop model of an artificial rigid trachea. Tracheal tubes were placed in the artificial trachea. Both cuffs were kept inflated at 25 cmH2O. Total 3 ml dyed water was placed above the cuff and leakage recorded under static and dynamic [5 cmH2O positive end-expiratory pressure (PEEP) alone or positive pressure ventilation plus 5 cmH2O PEEP] conditions. At the end of the dynamic experiments, PEEP was zeroed (PEEP alone) or the tracheal tubes were disconnected from the ventilator (positive pressure ventilation plus PEEP). In the static model, leakage flows [medians (range)] were 9.8 (6.2 to 20) for the cylindrical PVC, 1.3 (0.2 to 3.8) for the conical PVC, 0.03 (0.007 to 0.1) for the cylindrical polyurethane, 0.04 (0.003 to 0.2) for the conical polyurethane and 0.0 (0.0 to 0.0) ml min for the PVCdc cuff (P < 0.001, PVCdc vs. all other cuffs). In the dynamic setting, no leakage was detected for up to 60 min with any of the cuffs studied. Loss of PEEP or tracheal tube disconnection resulted in dye inflow alongside all cuffs except for the PVCdc (P < 0.001, PVCdc vs. all other cuffs). A 'pressure seal' incorporated in a double-cuffed tracheal tube prevented fluid passage into the lower airways. Clinically, this may translate into absence of inflow of bacteriologically contaminated secretions into the lungs and thus a lower incidence of ventilator-associated infection.

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

BackgroundWhen conventional high-volume, low-pressure cuffs of endotracheal tubes (ETTs) are inflated, channel formation due to folds in the cuff wall can occur. These channels facilitate microaspiration of subglottic secretions, which is the main pathogenic mechanism leading to intubation-related pneumonia. Ultrathin polyurethane (PU)-cuffed ETTs are developed to minimize channel formation in the cuff wall and therefore the risk of microaspiration and respiratory infections.MethodsWe systematically reviewed the available literature for laboratory and clinical studies comparing fluid leakage or microaspiration and/or rates of respiratory infections between ETTs with polyvinyl chloride (PVC) cuffs and ETTs with PU cuffs.ResultsThe literature search revealed nine in vitro experiments, one in vivo (animal) experiment, and five clinical studies. Among the 9 in vitro studies, 10 types of PU-cuffed ETTs were compared with 17 types of PVC-cuffed tubes, accounting for 67 vs. 108 experiments with 36 PU-cuffed tubes and 42 PVC-cuffed tubes, respectively. Among the clinical studies, three randomized controlled trials (RCTs) were identified that involved 708 patients. In this review, we provide evidence that PU cuffs protect more efficiently than PVC cuffs against fluid leakage or microaspiration. All studies with leakage and/or microaspiration as the primary outcome demonstrated significantly less leakage (eight in vitro and two clinical studies) or at least a tendency toward more efficient sealing (one in vivo animal experiment). In particular, high-risk patients intubated for shorter periods may benefit from the more effective sealing capacity afforded by PU cuffs. For example, cardiac surgery patients experienced a lower risk of early postoperative pneumonia in one RCT. The evidence that PU-cuffed tubes prevent ventilator-associated pneumonia (VAP) is less robust, probably because microaspiration is postponed rather than eliminated. One RCT demonstrated no difference in VAP risk between patients intubated with either PU-cuffed or PVC-cuffed tubes, and one before-after trial demonstrated a favorable reduction in VAP rates following the introduction of PU-cuffed tubes.ConclusionsCurrent evidence can support the use of PU-cuffed ETTs in high-risk surgical patients, while there is only very limited evidence that PU cuffs prevent pneumonia in patients ventilated for prolonged periods.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-016-1380-8) contains supplementary material, which is available to authorized users.

Endotracheal Tubes for Critically Ill Patients: An In Vivo Analysis of Associated Tracheal Injury, Mucociliary Clearance, and Sealing Effi cacy

Improvements in the design of the endotracheal tube (ETT) have been achieved in recent years. We evaluated tracheal injury associated with ETTs with novel high-volume low-pressure (HVLP) cuffs and subglottic secretions aspiration (SSA) and the effects on mucociliary clearance (MCC). Twenty-nine pigs were intubated with ETTs comprising cylindrical or tapered cuffs and made of polyvinylchloride (PVC) or polyurethane. In specific ETTs, SSA was performed every 2 h. Following 76 h of mechanical ventilation, pigs were weaned and extubated. Images of the tracheal wall were recorded before intubation, at extubation, and 24 and 96 h thereafter through a fluorescence bronchoscope. We calculated the red-to-green intensity ratio (R/G), an index of tracheal injury, and the green-plus-blue (G+B) intensity, an index of normalcy, of the most injured tracheal regions. MCC was assessed through fluoroscopic tracking of radiopaque markers. After 96 h from extubation, pigs were killed, and a pathologist scored injury. Cylindrical cuffs presented a smaller increase in R/G vs tapered cuffs (P = .011). Additionally, cuffs made of polyurethane produced a minor increase in R/G (P = .012) and less G+B intensity decline (P = .022) vs PVC cuffs. Particularly, a cuff made of polyurethane and with a smaller outer diameter outperformed all cuffs. SSA-related histologic injury ranged from cilia loss to subepithelial inflammation. MCC was 0.9 ± 1.8 and 0.4 ± 0.9 mm/min for polyurethane and PVC cuffs, respectively (P < .001). HVLP cuffs and SSA produce tracheal injury, and the recovery is incomplete up to 96 h following extubation. Small, cylindrical-shaped cuffs made of polyurethane cause less injury. MCC decline is reduced with polyurethane cuffs.

Post-operative pulmonary complications after non-cardiothoracic surgery.

Post-operative pulmonary complications (PPCs) occur in 5–10% of patients undergoing non-thoracic surgery and in 22% of high risk patients. PPCs are broadly defined as conditions affecting the respiratory tract that can adversely influence clinical course of the patient after surgery. Prior risk stratification, risk reduction strategies, performing short duration and/or minimally invasive surgery and use of anaesthetic technique of combined regional with general anaesthesia can reduce the incidence of PPCs. Atelectasis is the main cause of PPCs. Atelectasis can be prevented or treated by adequate analgesia, incentive spirometry (IS), deep breathing exercises, continuous positive airway pressure, mobilisation of secretions and early ambulation. Pre-operative treatment of IS is more effective. The main reason for post-operative pneumonia is aspiration along the channels formed by longitudinal folds in the high volume, low pressure polyvinyl chloride cuffs of the endotracheal tubes. Use of tapered cuff, polyurethane cuffs and selective rather than the routine use of nasogastric tube can decrease chances of aspiration. Acute lung injury is the most serious PPC which may prove fatal.

How to avoid microaspiration? A key element for the prevention of ventilator-associated pneumonia in intubated ICU patients.

Microaspiration of subglottic secretions through channels formed by folds in high volume-low pressure poly-vinyl chloride cuffs of endotracheal tubes is considered a significant pathogenic mechanism of ventilator-associated pneumonia (VAP). Therefore a series of prevention measures target the avoidance of microaspiration. However, although some of these can minimize microaspiration, benefits in terms of VAP prevention are not always obvious. Polyurethane-cuffed endotracheal tubes successfully reduce microaspiration but high quality data demonstrating VAP rate reduction are lacking. An analogous conclusion can be made regarding taper-shaped cuffs compared with classic barrel-shaped cuffs. More clinical data regarding these endotracheal tube designs are needed to demonstrate clinical value in addition to in vitro-based evidence. The clinical usefulness of endotracheal tubes developed for subglottic secretions drainage is established in multiple studies and confirmed by meta-analysis. Any change in cuff design will fail to prevent microaspiration if the cuff is insufficiently inflated. At least one well-designed trial demonstrated that continuous cuff pressure monitoring and control decrease the risk of VAP. Gel lubrication of the cuff prior to intubation temporarily hampers microaspiration through sludging the channels formed by folds in high volume-low pressure cuffs. As the beneficial effect of gel lubrication is temporarily, its potential to reduce VAP risk is probably nonsignificant. A minimum positive end-expiratory pressure of at least 5 cmH2O can be recommended as it reduces the risk of microaspiration in vitro and in vivo. One randomized controlled study demonstrated a reduced risk of VAP in patients ventilated with PEEP (5–8 cmH2O). Regarding head-of-bed elevation, it can be recommended to avoid supine positioning. Whether a 45° head-of-bed elevation is to be preferred above 25-30° head-of-bed elevation remains unproven. Finally, the routine monitoring of gastric residual volumes in mechanically ventilated patients receiving enteral nutrition cannot be recommended.

Association among duration of mechanical ventilation, cuff material of endotracheal tube, and postoperative nosocomial pneumonia in cardiac surgical patients: A prospective study

Postoperative pulmonary complications are a burden for high-risk surgical patients with a risk of aspiration of subglottic secretions along the polyvinyl chloride cuff. The introduction of a polyurethane cuff diminishes secretion leakage with a decreased rate of pneumonia. The aim of the current analysis was to determine the time at which a polyurethane cuffed endotracheal tube might be advantageous to prevent aspiration in a setting of high-risk surgical patients. The present investigation is based on published data obtained in postoperative cardiac surgical patients undergoing operation from 2006 to 2007. Cuff pressure was kept between 20 and 26 cmH2O intraoperatively and in the intensive care unit. The current post hoc analysis determines (1) the discriminatory cutoff value of intubation duration for predicting postoperative pneumonia and (2) the potential factors associated with prolonged intubation. Forty-three patients (32%) were diagnosed with early postoperative pneumonia. Receiver operating characteristics analysis revealed a cutoff value of 16.6 hours for the duration of mechanical ventilation to discriminate patients with postoperative pneumonia. A stepwise binary logistic regression analysis revealed that a polyvinyl chloride cuff was associated with a 10-fold increased risk for prolonged intubation. The current analyses provide evidence that among cardiac surgical patients, mechanical ventilation more than 16.6 hours is associated with an increased likelihood of postoperative pneumonia.

Comparison of prophylactic effects of polyurethane cylidrical or tapered cuff and polyvinyl chloride cuff endotracheal tubes on ventilator-associated pneumonia

Peirovifar, A.1; Gharehbaghi, Mostafa M.2; Pour, Mahmood A.3; Bakhtiari, Z.3 Author Information

Condensation of humidified air in the inflation line of a polyurethane cuff precludes correct continuous pressure monitoring during mechanical ventilation.

Within continuously controlled limits of cuff pressure, an endotracheal tube cuff made of polyurethane (PU) prevents secretion inflow better than a conventional polyvinylchloride cuff. However, the temperature difference between ventilator gas and the air inside a PU cuff produces condensation droplets that accumulate in the cuff inflation canal. We investigated whether condensation influenced continuous cuff pressure monitoring. A PU-cuffed tube was placed into an artificial trachea and connected to a ventilator and test lung. An additional line was inserted at the distal cuff end to directly measure pressure inside the cuff. Methylene blue instillation via the inflation line mimicked condensation. Inspiratory (Pinsp) and expiratory (Pexp) pressures were continuously recorded. Six consecutive experiments were performed comparing pressures at baseline (T0) and at 24 h (T24). Shortly after dye instillation, pressures recorded at the inflation canal became permanently fixed at 25 cmH2O. In contrast, pressures measured directly in the cuff progressively decreased (mean Pinsp 30 ± 3 vs. 20 ± 2 cmH2O and mean Pexp 25 ± 0 vs. 12 ± 2 cmH2O, T0 vs. T24, both P < 0.05). Thus, condensation in the inflation line of a PU-cuffed tube renders continuous cuff pressure monitoring unreliable, thereby increasing the risk for microaspiration.

Benchtop study of leakages across the Portex, TaperGuard and Microcuff Endotracheal tubes under simulated clinical conditions

OBJECTIVES. To compare three endotracheal tubes for leakage across the cuff (microaspiration) under a comprehensive set of simulated clinical situations. These were the Mallinckrodt TaperGuard (Covidien, US) with a tapered polyvinyl chloride cuff; the KimVent Microcuff (Kimberly-Clark Health Care, US) with a cylindrical polyurethane cuff; and a conventional Portex (Smiths Medical International Ltd, UK) with a globular polyvinyl chloride cuff. DESIGN. A benchtop experimental study. SETTING AND MATERIALS. A silicone cylinder serving as the model trachea was intubated with each of the three endotracheal tubes, one at a time. A total of 20 mL of water were added above the cuff and leakage measured every minute for 20 minutes under five simulated mechanical ventilation scenarios, including different positive end-expiratory pressure levels, and disconnection with and without spontaneous breathing efforts. Each scenario was studied under three cuff pressures of 10, 20 and 30 cm H2O, and then repeated with the application of a continuous suction force of 200 cm H2O, and leakage measured every minute for 3 minutes. RESULTS. The outcome of interest was the cumulative amount of leakage. The Microcuff endotracheal tubes with an ultrathin polyurethane cuff consistently provided the best protection against microaspiration under all simulated clinical situations, followed by TaperGuard with a tapered cuff, and lastly Portex with a globular polyvinyl chloride cuff. Clinical scenarios associated with the greatest leakage were mechanical ventilation with zero positive end-expiratory pressure, circuit disconnection with spontaneous breathing efforts, application of suction, and a low cuff pressure. CONCLUSIONS. Microcuff endotracheal tubes outperformed TaperGuard and Portex endotracheal tubes in preventing microaspiration, which is one of the major mechanisms for ventilator-associated pneumonia.

Assessment of intraoperative microaspiration: does a modified cuff shape improve sealing?

Intra-operative aspiration of oropharyngeal secretions is associated with post-operative pneumonia. The use of endotracheal tubes (ETTs) with a modified cuff shape could be one preventive action. In this clinical, prospective, randomised controlled trial, we hypothesised that altering the cuff shape to a tapered shape could reduce the aspiration incidence. The primary outcome was aspiration of dye solution into the trachea. Patients scheduled for lumbar surgery were intubated with either an ETT with a barrel-shaped polyvinylchloride cuff (control group, n = 30) or tapered-shaped polyvinylchloride cuff (intervention group, n = 30). Subsequently, instillation with methylthioninium chloride was performed. At 10, 30, 60, 90, and 120 min after intubation, bronchoscopy was performed assessing the degree of dye descent along the cuff and digitally stored. Single blind review of the videoclips provided data on incidence of dye aspiration and depth of penetration along the cuff. The traditional cuff showed descent of dye into the trachea in 20% of the patients. Although a tapered-shaped polyvinylchloride cuff leaked up to the second third of the cuff, no dye leakage into the trachea was observed. The use of a tapered-shaped cuff had a protective role against aspiration (T30: OR 3.0, CI 1.57-5.75; P = 0.001). Short-term use of tapered-shaped polyvinylchloride cuffs in surgical patients results in more effective sealing of the tracheal lumen in comparison with a traditional barrel-shaped polyvinylchloride cuffs. Further evaluation is needed to determine whether a reduction in post-operative pneumonia can be demonstrated when these cuffs are used.

Benchtop study comparing leakages across cuffs of three endotracheal tubes

The aim was to compare two novel endotracheal tubes (ETT), Mallinckrodt TaperGuard (TG, tapered polyvinyl chloride (PVC) cuff) and KimVent Microcuff (MC, cylindrical polyurethrane cuff), with conventional Portex (PT, globular PVC cuff) in leakages across cuffs (microaspiration) under simulated clinical situations. It has been shown that globular PVC cuffs protect poorly against leakages due to microchannels formed from infolding of redundant cuff material [1]. We hypothesized that TG and MC better prevent microaspiration, which is a major mechanism of ventilator-associated pneumonia (VAP).

Comparison of air‐sealing characteristics of tapered‐ vs. cylindrical‐shaped high‐volume, low‐pressure tube cuffs

This study aimed at comparing air-sealing characteristics of the new tapered-shaped tracheal tube cuffs with cylindrical tube cuffs. Tracheal tubes with tapered-shaped polyurethane (PU) and polyvinyl chloride (PVC) cuffs as well as standard cylindrical-shaped cuffs made of PU and PVC (Covidien, Athlone, Ireland) were investigated. A tracheal model attached to a test lung was intubated, and cuffs were inflated to 10, 15, 20, 25 and 30 cm H(2)O. The test lung was ventilated with intermittent positive pressure ventilation at peak inspiratory pressures (PIPs) of 20 and 25 cm H(2)O. Air leakage was assessed by spirometry and measurement of sevoflurane concentration passing the cuff at the upper cuff border using an anaesthetic gas analyser. Experiments were repeated four times with new tracheal tubes for each run. Statistical comparisons were done using Mann-Whitney U-test with level of significance at P < 0.05. The tapered-shaped PVC tube cuff demonstrated a significantly lower air leakage determined by spirometry than the cylindrical-shaped cuff at both PIPs (20 and 25 cm H(2)O). Similarly, sevoflurane leakage was less with the tapered PVC cuff particularly at higher cuff pressures. With the PU cuff, reduction in air leakage by a tapered-shaped compared with a cylindrical-shaped tube cuff was not significant. A tapered-shaped tube cuff considerably improves air-sealing characteristics of PVC tube cuffs and allows thereby reducing cuff pressure required for sufficient ventilation. In tube cuffs made of PU that exhibits superior sealing characteristics compared with PVC, a tapered shape failed to result in a further reduction of air leakage.

Comparison of a Novel Lycra Endotracheal Tube Cuff to Standard Polyvinyl Chloride Cuff and Polyurethane Cuff for Fluid Leak Prevention

A high-volume low-pressure endotracheal tube (ETT) cuff forms folds along its contact with the trachea, allowing mucus leakage into the lungs. We developed a thin-walled ETT cuff made of Lycra polyurethane. In vitro, we tested 6 of each of the new prototype Lycra cuff, the Mallinkrodt Hi-Lo ETT (polyvinyl chloride cuff), and the Kimberly-Clark Microcuff ETT (polyurethane cuff), for leakage, in an acrylic mock trachea (inner diameter 20-mm), with a cuff inflation pressure of 20 cm H(2)O. We poured 15 mL of methylene-blue colored water into the acrylic tube above the cuff and observed for leakage for 24 hours. The Lycra cuffs had no folds upon inflation in the mock trachea and completely prevented fluid leakage for 24 hours (P < .001 vs the Hi-Lo and the Microcuff). The average leakage past the Hi-Lo was 1,182 ± 1,321 mL/h. The average leakage past the Microcuff was 1.2 ± 0.4 mL/h (P < .001 vs the Hi-Lo). Our Lycra cuff provided complete tracheal sealing in vitro.