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

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Randomized, multicenter trial of lateral Trendelenburg versus semirecumbent body position for the prevention of ventilator-associated pneumonia.

PURPOSE: The lateral Trendelenburg position (LTP) may hinder the primary pathophysiologic mechanism of ventilator-associated pneumonia (VAP). We investigated whether placing patients in the LTP would reduce the incidence of VAP in comparison with the semirecumbent position (SRP). METHODS: This was a randomized, multicenter, controlled study in invasively ventilated critically ill patients. Two preplanned interim analyses were performed. Patients were randomized to be placed in the LTP or the SRP. The primary outcome, assessed by intention-to-treat analysis, was incidence of microbiologically confirmed VAP. Major secondary outcomes included mortality, duration of mechanical ventilation, and intensive care unit length of stay. RESULTS: At the second interim analysis, the trial was stopped because of low incidence of VAP, lack of benefit in secondary outcomes, and occurrence of adverse events. A total of 194 patients in the LTP group and 201 in the SRP group were included in the final intention-to-treat analysis. The incidence of microbiologically confirmed VAP was 0.5% (1/194) and 4.0% (8/201) in LTP and SRP patients, respectively (relative risk 0.13, 95% CI 0.02-1.03, p = 0.04). The 28-day mortality was 30.9% (60/194) and 26.4% (53/201) in LTP and SRP patients, respectively (relative risk 1.17, 95% CI 0.86-1.60, p = 0.32). Likewise, no differences were found in other secondary outcomes. Six serious adverse events were described in LTP patients (p = 0.01 vs. SRP). CONCLUSIONS: The LTP slightly decreased the incidence of microbiologically confirmed VAP. Nevertheless, given the early termination of the trial, the low incidence of VAP, and the adverse events associated with the LTP, the study failed to prove any significant benefit. Further clinical investigation is strongly warranted; however, at this time, the LTP cannot be recommended as a VAP preventive measure. CLINICALTRIALS. GOV IDENTIFIER: NCT01138540.

Pathogenic Link Between Postextubation Pneumonia and Ventilator-Associated Pneumonia: An Experimental Study.

BACKGROUND: The presence of an endotracheal tube is the main cause for developing ventilator-associated pneumonia (VAP), but pneumonia can still develop in hospitalized patients after endotracheal tube removal (postextubation pneumonia [PEP]). We hypothesized that short-term intubation (24 hours) can play a role in the pathogenesis of PEP. To test such hypothesis, we initially evaluated the occurrence of lung colonization and VAP in sheep that were intubated and mechanically ventilated for 24 hours. Subsequently, we assessed the incidence of lung colonization and PEP at 48 hours after extubation in sheep previously ventilated for 24 hours. METHODS: To simulate intubated intensive care unit patients placed in semirecumbent position, 14 sheep were intubated and mechanically ventilated with the head elevated 30° above horizontal. Seven of them were euthanized after 24 hours (Control Group), whereas the remaining were euthanized after being awaken, extubated, and left spontaneously breathing for 48 hours after extubation (Awake Group). Criteria of clinical diagnosis of pneumonia were tested. Microbiological evaluation was performed on autopsy in all sheep. RESULTS: Only 1 sheep in the Control Group met the criteria of VAP after 24 hours of mechanical ventilation. However, heavy pathogenic bacteria colonization of trachea, bronchi, and lungs (range, 10-10 colony-forming unit [CFU]/g) was reported in 4 of 7 sheep (57%). In the Awake Group, 1 sheep was diagnosed with VAP and 3 developed PEP within 48 hours after extubation (42%), with 1 euthanized at 30 hours because of respiratory failure. On autopsy, 5 sheep (71%) confirmed pathogenic bacterial growth in the lower respiratory tract (range, 10-10 CFU/g). CONCLUSIONS: Twenty-four hours of intubation and mechanical ventilation in semirecumbent position leads to significant pathogenic colonization of the lower airways, which can promote the development of PEP. Strategies directed to prevent pathogenic microbiological colonization before and after mechanical ventilation should be considered to avert the onset of PEP.

Spatial orientation and mechanical properties of the human trachea: a computed tomography study.

BACKGROUND: The literature generally describes the trachea as oriented toward the right and back, but there is very little detailed characterization. Therefore, the aim of this study was to precisely determine the spatial orientation and to better characterize the physical properties of the human trachea. METHODS: We analyzed lung computed tomography scans of 68 intubated and mechanically ventilated subjects suffering from acute lung injury/ARDS at airway pressures (Paw) of 5, 15, and 45 cm H2O. At each Paw, the inner edge of the trachea from the subglottal space to the carina was captured. Tracheal length and diameter were measured. Tracheal orientation and compliance were estimated from processing barycenter and surface tracheal sections. RESULTS: Tracheal orientation at a Paw of 5 cm H2O showed a 4.2 ± 5.3° angle toward the right and a 20.6 ± 6.9° angle downward toward the back, which decreased significantly while increasing Paw (19.4 ± 6.9° at 15 cm H2O and 17.1 ± 6.8° at 45 cm H2O, P < .001). Tracheal compliance was 0.0113 ± 0.0131 mL/cm H2O/cm of trachea length from 5 to 15 cm H2O and 0.004 ± 0.0041 mL/cm H2O/cm of trachea length from 15 to 45 cm H2O (P < .001). Tracheal diameter was 19.6 ± 3.4 mm on the medial-lateral axis and 21.0 ± 4.3 mm on the sternal-vertebral axis. CONCLUSIONS: The trachea is oriented downward toward the back at a 20.6 ± 6.9° angle and slightly toward the right at a 4.2 ± 5.3° angle. Understanding tracheal orientation may help in enhancing postural drainage and respiratory physiotherapy, and knowing the physical properties of the trachea may aid in endotracheal tube cuff design.

Effects of manual rib cage compressions on expiratory flow and mucus clearance during mechanical ventilation.

OBJECTIVES: We investigated the effects of two different types of manual rib cage compression on expiratory flow and mucus clearance during prolonged mechanical ventilation in pigs. DESIGN: Prospective randomized animal study. SETTING: Animal research facility, University of Barcelona, Spain. SUBJECTS: Nine healthy pigs. MEASUREMENT AND MAIN RESULTS: Pigs were tracheally intubated, sedated, paralyzed, and mechanically ventilated. The animals were prone on a surgical bed in the anti-Trendelenburg position. The experiments were carried out at approximately 60 and 80 hrs from the beginning of mechanical ventilation. Two types of manual rib cage compressions were tested: Hard and brief rib cage compressions synchronized with early expiratory phase (hard manual rib cage compression) and soft and gradual rib cage compressions applied during the late expiratory phase (soft manual rib cage compression). The interventions were randomly applied for 15min with a 15-min interval between treatments. Respiratory flow and mucus movement were assessed during the interventions. Respiratory mechanics and hemodynamics were assessed prior to and after the interventions. Peak expiratory flow increased to 60.1±7.1L/min in comparison to 51.2±4.6L/min without treatment (p < 0.0015) and 48.7±4.3L/min with soft manual rib cage compression (p = 0.0002). Similarly, mean expiratory flow increased to 28.4±5.2L/min during hard manual rib cage compression vs. 15.9±2.2 and 16.6±2.8L/min without treatment and soft manual rib cage compression, respectively (p = 0.0006). During hard manual rib cage compression, mucus moved toward the glottis (1.01 ± 2.37mm/min); conversely, mucus moved toward the lungs during no treatment and soft manual rib cage compression, -0.28 ± 0.61 and -0.15±0.95mm/min, respectively (p = 0.0283). Soft manual rib cage compression slightly worsened static lung elastance and cardiac output (p = 0.0391). CONCLUSIONS: Hard manual rib cage compression improved mucus clearance in animals positioned in the anti-Trendelenburg position. The technique appeared to be safe. Conversely, soft manual rib cage compression was not effective and potentially unsafe. These findings corroborate the predominant role of peak expiratory flow on mucus clearance.

Effects of tracheal orientation on development of ventilator-associated pneumonia: an experimental study.

PURPOSE: Orientation of the trachea and tracheal tube below horizontal may prevent aspiration of oropharyngeal secretions into the lungs, which is a pivotal pathway in the pathogenesis of ventilator-associated pneumonia (VAP). The incidence of VAP was evaluated in swine with orientation of trachea and tracheal tube above horizontal (model of semirecumbent position, currently recommended in patients) and below horizontal. METHODS: Twenty-six mini-pigs were randomized into four groups: (A) eight mechanically ventilated with orientation of trachea 45° above horizontal for 72 h. In the remaining groups (B, C, D) the trachea was oriented 10° below horizontal, with (B) six mechanically ventilated for 72 h, (C) six mechanically ventilated for 72 h with enteral feeding, and (D) six mechanically ventilated for 168 h with enteral feeding. At the end of the study period, all pigs were sacrificed and the clinical diagnosis of VAP was microbiologically evaluated. No antibiotics were administered. RESULTS: All eight pigs kept orientated with the trachea 45° above horizontal developed VAP and respiratory failure (PaO(2)/F(i)O(2) = 132 ± 139 mmHg) with a median of 5.5 pulmonary lobes out of 6 colonized with average colonization of 9.3 × 10(7) CFU/g. None of the 18 pigs kept oriented with the trachea below horizontal developed VAP; 16 had sterile lungs, while 2, ventilated for 7 days, developed a low level of colonization. CONCLUSIONS: Orientation of the trachea above horizontal was uniformly associated with VAP and respiratory failure; positioning the trachea below horizontal consistently prevented development of VAP.

A clinical assessment of the Mucus Shaver: a device to keep the endotracheal tube free from secretions.

OBJECTIVE: : We evaluated a new device designed to clean the endotracheal tube in mechanically ventilated patients, the Mucus Shaver. DESIGN: : Prospective, randomized trial. SETTING: : University hospital intensive care unit. PATIENTS: : We enrolled 24 patients expected to remain ventilated for >72 hrs. INTERVENTIONS: : The Mucus Shaver is a concentric inflatable catheter for the removal of mucus and secretions from the interior surface of the endotracheal tube. The Mucus Shaver is advanced to the distal endotracheal tube tip, inflated, and subsequently withdrawn over a period of 3-5 secs. Patients were prospectively randomized within 2 hrs of intubation to receive standard endotracheal tube suctioning treatment or standard suctioning plus Mucus Shaver use until extubation. MEASUREMENTS AND MAIN RESULTS: : During the study period, demographic data, recent medical history, adverse events, and staff evaluation of the Mucus Shaver were recorded. At extubation, each endotracheal tube was removed, cultured, and analyzed by scanning electron microscopy. Twelve patients were assigned to the study group and 12 were assigned to the control group. No adverse events related to the use of the Mucus Shaver were observed. At extubation, only one endotracheal tube from the Mucus Shaver group was colonized, whereas in the control group ten endotracheal tubes were colonized (8% vs. 83%; p < .001). Scanning electron microscopy showed little secretions on the endotracheal tubes from the study group, whereas thick bacterial deposits were present on all the endotracheal tubes from the control group (p < .001 by Fisher exact test, using a maximum biofilm thickness of 30 µm as cut-off). The nursing staff was satisfied by the overall safety, feasibility, and efficacy of the Mucus Shaver. CONCLUSIONS: : The Mucus Shaver is a safe, feasible, and efficient device for endotracheal tube cleaning in the clinical setting. The Mucus Shaver is helpful in preventing endotracheal tube colonization by potentially harmful microorganisms.

Effects of duty cycle and positive end-expiratory pressure on mucus clearance during mechanical ventilation*.

OBJECTIVES: During mechanical ventilation, air flows may play a role in mucus transport via two-phase gas liquid flow. The aim of this study was to evaluate effects of duty cycles and positive end-expiratory pressure on mucus clearance in pigs using mechanical ventilation, and to assess their safety. DESIGN: Prospective randomized animal study. SETTING: Animal research facility, University of Barcelona, Spain. SUBJECTS: Eight healthy pigs. INTERVENTIONS: Pigs were intubated and on volume-control mechanical ventilation for up to 84 hrs. After 4, 24, 48, and 72 hrs of mechanical ventilation, six levels of duty cycle (0.26, 0.33, 0.41, 0.50, 0.60, and 0.75) with no associated positive end-expiratory pressure or 5 cm H2O of positive end-expiratory pressure were randomly applied. Surgical bed was oriented 30 degrees in the reverse Trendelenburg position, as in the semirecumbent position. MEASUREMENT AND MAIN RESULTS: Inspiratory and expiratory flows and hemodynamics were measured after each 30-min ventilation period. Mucus movement was assessed through fluoroscopy tracking of radio-opaque markers. Mucus velocity was described by a positive vector (toward the glottis) or negative vector (toward the lungs). No effect of positive end-expiratory pressure was found; however, as duty cycle was increasingly prolonged, a trend toward reduced velocity of mucus moving toward the lungs and increased outward mucus velocity was found (p = .064). Two clusters of mucus velocities were identified as duty cycle was prolonged beyond 0.41. Thus, duty cycle >0.41 increased mean expiratory-inspiratory flow bias from -4.1 ± 4.6 to 7.9 ± 5.9 L/min (p < .0001) and promoted outward mucus velocity from -0.22 ± 1.71 mm/min (range, -5.78 to 2.42) to 0.53 ± 1.06 mm/min (-1.91 to 3.88; p = .0048). Duty cycle of 0.75 resulted in intrinsic positive end-expiratory pressure (2.1 ± 1.1 cm H2O [p < .0001] vs. duty cycle 0.26-0.5), with no hemodynamic compromise. CONCLUSIONS: In the semirecumbent position, mucus clearance is improved with prolongation of the duty cycle. However, in clinical practice, positive findings must be balanced against the potentially adverse hemodynamic and respiratory effects.

Comparison of a novel lycra endotracheal tube cuff to standard polyvinyl chloride cuff and polyurethane cuff for fluid leak prevention.

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: Our Lycra cuff provided complete tracheal sealing in vitro.

Decreasing pulmonary ventilation through bicarbonate ultrafiltration: an experimental study.

OBJECTIVE: : To demonstrate the technical feasibility of CO2 removal with a commercial hemofilter and a replacement solution containing sodium hydroxide to replace bicarbonate. DESIGN: : Prospective animal experiment in sheep. SUBJECTS: : Seven mixed-breed female sheep. INTERVENTIONS: : Blood ultrafiltrate containing half of the metabolic production of CO2 was removed with a commercial hemofilter and a replacement solution containing sodium hydroxide was given as replacement. Minute ventilation was lowered to less than half of its baseline value. Ultrafiltration was stopped at 18 hrs, and Paco2 was allowed to increase for about 1 hr; at this time, the sheep were electively killed. MEASUREMENTS AND MAIN RESULTS: : Every 6 hrs, blood was sampled from the carotid artery, the pulmonary artery, and from the extracorporeal perfusion circuit (before the hemofilter, immediately after the hemofilter, and after mixing with the replacement solution). To maintain normocapnia, minute ventilation was reduced from 3.8 +/- 0.1 L/min to 1.9 +/- 0.7 L/min; Paco2 remained near constant during the study. The average blood pH, after mixing with the replacement solution, was 7.64 +/- 0.12. One hour after the ultrafiltration had stopped, Paco2 had increased from 36.7 +/- 4.2 torr (4.9 +/- 0.6 kPa) to 59.6 +/- 9 torr (7.9 +/- 1.2 kPa) (p < .01) and blood pH had decreased from 7.317 +/- 0.041 to 7.151 +/- 0.051 (p < .01). CONCLUSION: : CO2 removal with bicarbonate ultrafiltration may be an effective treatment for patients with respiratory failure.

Internally coated endotracheal tubes with silver sulfadiazine in polyurethane to prevent bacterial colonization: a clinical trial.

OBJECTIVE: Coated medical devices have been shown to reduce catheter-related infections. We coated endotracheal tubes (ETT) with silver sulfadiazine (SSD), and tested them in a clinical study to assess the feasibility, safety, and efficacy of preventing bacterial colonization. DESIGN: A prospective, randomized clinical trial, phase I-II. SETTING: Academic intensive care unit (ICU). PARTICIPANTS: Forty-six adult patients expected to need 12-24 h of intubation were randomized into two groups. INTERVENTIONS: Patients were randomized to be intubated with a standard non-coated ETT (St-ETT, n=23; control group), or with a SSD-coated ETT (SSD-ETT, n=23). MEASUREMENTS AND RESULTS: Coating with SSD prevented bacterial colonization of the ETT (frequency of colonization: SSD-ETT 0/23, St-ETT 8/23; p<0.01). No organized bacterial biofilm could be identified on the lumen of any ETT; however, SSD was associated with a thinner mucus layer (in the SSD-ETT secretion deposits ranged from 0 to 200 microm; in the St-ETT deposits ranged between 50 and 700 microm). No difference was observed between the two groups in the tracheobronchial brush samples (frequency of colonization: SSD-ETT 0/23, St-ETT 2/23; p=0.48). No adverse reactions were observed with the implementation of the novel device. CONCLUSION: SSD-ETT can be safely used in preventing bacterial colonization and narrowing of the ETT in patients intubated for up to 24 h (mean intubation time 16 h).

Antimicrobial-coated endotracheal tubes: an experimental study.

OBJECTIVE: Antibiotic-resistant bacterial biofilm may quickly form on endotracheal tubes (ETTs) and can enter the lungs, potentially causing pneumonia. In an attempt to prevent bacterial colonization, we developed and tested in an in-vitro study and animal study several antibacterial-coated ETTs (silver sulfadiazine with and without carbon in polyurethane, silver sulfadiazine and chlorhexidine with and without carbon in polyurethane, silver-platinum with and without carbon in polyurethane, chlorhexidine in polyurethane, and rose bengal for UV light). DESIGN, SETTING, ANIMALS, INTERVENTIONS: After preliminary studies, silver sulfadiazine in polyurethane (SSD-ETT) was selected among the coatings to be challenged every 24 h with 10(4)-10(6) Pseudomonas aeruginosa/ml and evaluated at 6 h, 24 h, and 72 h with standard microbiological studies, scanning electron microscopy, and confocal scanning microscopy. Subsequently, eight sheep were randomized to receive either a SSD-ETT or a standard ETT (St-ETT). After 24 h of mechanical ventilation, standard microbiological studies were performed together with scanning electron microscopy and confocal microscopy. MEASUREMENTS AND RESULTS: In the in-vitro study SSD-ETT remained bacteria-free for up to 72 h, whereas St-ETT showed heavy P. aeruginosa growth and biofilm formation (p < 0.01). In sheep, the SSD-ETT group showed no bacterial growth in the ETT, ventilator tubing, and lower respiratory tract, while heavy colonization was found in the St-ETT (p < 0.01), ventilator tubing (p=0.03), and lower respiratory tract (p < 0.01). CONCLUSION: This study describes several effective and durable antibacterial coatings for ETTs. Particularly, SSD-ETT showed prevention against P. aeruginosa biofilm formation in a 72-h in-vitro study and lower respiratory tract colonization in sheep mechanically ventilated for 24 h.

A double-layer tracheal tube cuff designed to prevent leakage: a bench-top study.

OBJECTIVE: We designed a new endotracheal tube (ETT) cuff that does not form the folds that cause leakage of colonized subglottic secretions upon inflation within the trachea: a standard high-volume low-pressure cuff was draped with a second, highly elastic cuff made of a low-protein guayule natural latex rubber with 0.5 ml gel between the cuffs. We compared this prototype ETT cuff with four commercially available ETTs for efficacy in the prevention of fluid leakage across the cuff. DESIGN: In vitro study. MEASUREMENTS AND RESULTS: We compared fluid leakage in our prototype cuff with that in four commercially available ETTs. Three cylindrical glass tubes 16, 20, and 22 mm in diameter were used as model tracheas, and five different intracuff pressures (20, 25, 30, 40, and 50 cmH(2)O) were tested. Each test was repeated three times with new ETTs. The guayule latex ETT cuff showed an average fluid leakage of 0.0007 +/- 0.002 ml/min which was significantly lower than that in any of the other ETTs (Microcuff 0.07 +/- 0.09, Mallinckrodt/Hi-Lo Evac 5 +/- 5, Euromedical 7 +/- 4, Sheridan/CF 41 +/- 69). CONCLUSIONS: Our prototype ETT cuff significantly reduced fluid leakage in this bench-top study. In vivo testing and evaluation is to follow.

Following tracheal intubation, mucus flow is reversed in the semirecumbent position: possible role in the pathogenesis of ventilator-associated pneumonia.

OBJECTIVES: Critically ill intubated patients are positioned in the semirecumbent position to prevent pneumonia. In tracheally intubated sheep, we investigated the effects of gravitational force on tracheal mucus transport and on bacterial colonization of the respiratory system. DESIGN: Prospective randomized animal study. SETTING: Animal research facility at the National Institutes of Health. SUBJECTS: Sixteen healthy sheep. INTERVENTIONS: Spontaneously breathing or mechanically ventilated sheep were randomized to be positioned with the orientation of the trachea above (40 degrees, trachea-up) or below (5 degrees, trachea-down) horizontal. MEASUREMENTS AND MAIN RESULTS: Tracheal mucus velocity was measured through radiographic tracking of radiopaque tantalum disks, insufflated into the trachea. After 24 hrs, sheep were euthanized, and samples from the airways and lungs were taken for microbiological analysis. The proximal trachea was colonized in all sheep. In trachea-down sheep, all mucus moved toward the glottis at a mean velocity of 2.1 +/- 1.1 mm/min. When mucus reached the endotracheal tube, it either entered the endotracheal tube or was lodged at the inflated endotracheal tube cuff. In all trachea-up sheep, abnormal tracheal mucus clearance was found. Mucus, mostly on the nondependent part of the trachea, moved toward the glottis at an average velocity of 2.2 +/- 2.0 mm/min and constantly accumulated at the inflated endotracheal tube cuff. From the proximal trachea, mucus eventually moved toward the lungs on the dependent part of the trachea, leading to an "intratracheal route" of colonization of the lungs. Pneumonia was found in 6/8 of trachea-up sheep and the same microorganisms were isolated from the lungs and the proximal trachea. No pneumonia was found in trachea-down sheep (p = .007). CONCLUSIONS: The study indicates that following tracheal intubation gravitational force influences tracheal mucus clearance. When the trachea is oriented above horizontal, a flow of mucus from the proximal trachea toward the lungs is highly associated with bacterial colonization of the airways and pneumonia.

A comparison of a new, ultrathin-walled two-stage twin endotracheal tube and a conventional endotracheal tube in very premature infants with respiratory distress syndrome: a pilot study.

This was a pilot study to test the feasibility of use of the ultrathin-walled two-stage twin endotracheal tube (UTTS-T-ETT), with one half to one third the resistance to gas flow and one third to one seventh the dead space of a conventional tracheal tube, in very premature infants. Twenty-eight infants with gestational age 24 to 28 weeks and birthweight >/= 500 g with respiratory distress syndrome requiring intubation and mechanical ventilation were randomly assigned to be intubated with either the UTTS-T-ETT (13 infants) or with a conventional ETT (15 infants). The infants in the two groups were similar in GA, birthweight, age of entry in the study, and initial ventilator settings. Indications for intubation and extubation were standardized. To evaluate the feasibility of the UTTS-T-ETT, complications with insertion of the endotracheal tube, traumatic injury of the upper airway, number of accidental extubations, number of re-intubations after attempted extubation, number of x-ray/days of mechanical ventilation, prevalence of atelectasis, prevalence of air-leak syndrome, duration of ventilation, bronchopulmonary dysplasia, length of stay, and mortality in the two groups were compared. No significant differences in the outcomes were observed. Specifically, no complications during intubation or traumatic injury of the upper airway due to indwelling ETT were observed in either group. The proportion of failed extubation attempts was 7% in the UTTS-T-ETT V 40% in the conventional ETT group ( P = 0.08). The use of the UTTS-T-ETT is feasible in preterm infants. There was no difference in adverse events associated with its use compared with a conventional ETT. Given the proven in vitro advantages and a favorable trend toward facilitation of extubation in this pilot study, a larger randomized trial to assess clinical benefit and confirm safety is indicated.

A 72-hour study to test the efficacy and safety of the "Mucus Slurper" in mechanically ventilated sheep.

OBJECTIVE: In patients intubated with endotracheal tubes (ETTs), suctioning is routinely performed to remove mucus from within the ETT and trachea. The Mucus Slurper is a novel ETT with built-in suction ports arranged radially at its tip. We evaluated the safety and efficacy of the Mucus Slurper, compared with conventional tracheal suction, to prevent airway obstruction in sheep with the ETT and trachea oriented below horizontal. DESIGN: Prospective randomized animal study. SETTING: Animal research facility at the National Institutes of Health. SUBJECTS: Twelve healthy sheep. INTERVENTIONS: Sheep were randomized to be intubated with either the Mucus Slurper (study group) or a Hi-Lo Tracheal Tube (Mallinckrodt, St. Louis, MO) (control group) and mechanically ventilated for 72 hrs. In the study group, automatic, timed tracheal aspiration lasted 0.3 secs, was repeated every 2 mins, and was synchronized with the early expiratory phase. In the control group, tracheal suction was performed every 6 hrs or as required. MEASUREMENTS AND MAIN RESULTS: In the control group, tracheal secretions accumulated progressively within the ETT and the trachea. In the study group, all mucus that reached the tip of the Mucus Slurper was aspirated, keeping the lumen of the ETT, and proximal trachea, free from secretions. In the study group, expiratory water trap protein concentration, a crude index to measure mucus drainage through the ETT, was consistently less than the control group (p < .001). At autopsy, no macroscopic injury to the tracheal mucosa was found in either group. In the study group, the respiratory circuit was less colonized than in the control group. There were no statistically significant differences between the two groups in bacterial colonization of the lungs/bronchi. CONCLUSIONS: The Mucus Slurper, combined with orientation of the trachea below horizontal, prevents accumulation of secretions within the lumen of the ETT and trachea, without need for conventional tracheal suctioning.

The Mucus Slurper: A novel tracheal tube that requires no tracheal tube suctioning. A preliminary report.

OBJECTIVE: The buildup of mucus within the endotracheal tube (ETT) progressively reduces its internal volume. We devised the Mucus Slurper as an integral part of the tracheal tube to aspirate all mucus automatically at its distal tip. DESIGN AND SETTING: In vitro, and in vivo studies in sheep at the National Institutes of Health, NHLBI, PCCMB. SUBJECTS: Six sheep, sedated, paralyzed, and mechanically ventilated INTERVENTIONS: We evaluated the Mucus Slurper in vitro, and we evaluated its efficacy and safety in three healthy sheep during 24 h on volume-controlled mechanical ventilation in comparison to three sheep managed with open tracheal tube suctioning. MEASUREMENTS AND RESULTS: In vitro: with the Mucus Slurper connected to a source of vacuum of 450-500 mmHg the total volume of a single suction lasting 0.1, 0.2, and 0.3 s was, respectively, 75.4 +/- 7.9, 114.5 +/- 4.6, and 143.4 +/- 8.7 ml; with the measured vacuum within the lumen of the Mucus Slurper ring of 37 cmH2O. In vivo: during mechanical ventilation we aspirated through the Mucus Slurper 13.4 +/- 3.3 cc mucus/24 h. During the course of single aspiration the Mucus Slurper never affected the level of applied PEEP. The tracheal tube was free of tracheal secretions in the Mucus Slurper group while thin secretions were found within the ETT in the control group. CONCLUSION: The Mucus Slurper is a novel device designed to keep the tracheal tube and proximal trachea free of mucus. In studies in sheep lasting 24 h the Mucus Slurper was safe and prevented all mucus accumulation within the ETT.