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 ventilatedInterventions 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.Patent has been applied for the Mucus Slurper by National Institutes of Health     

Antibacterial-coated tracheal tubes cleaned with the Mucus Shaver

OBJECTIVE: To assess the long-term benefit from antibacterial coatings of the tracheal tube (ETT), and to keep clean the lumen of the ETT. DESIGN: Experimental animal study. SETTING: USA National Institutes of Health. SUBJECTS: Twelve sheep. INTERVENTIONS: Twelve ETTs were internally dip-coated with a silver-sulfadiazine in polyurethane. We developed a concentric inflatable silicone rubber "razor", the Mucus Shaver (MS), to shave the ETT lumen free of mucus. In a single pass, we cleaned all mucus from the internal surface of the ETT. Control group: Five intubated sheep were mechanically ventilated for 72 h. The ETT was suctioned every 6 h. Study group: Six sheep were intubated and mechanically ventilated for 72 h. The ETT was suctioned and cleaned with the MS every 6 h. An additional sheep was intubated and mechanically ventilated for 168 h. Bacteriologic studies and scanning electron microscopy were performed to assess bacterial colonization and thickness of secretions on the internal surface of the ETT. MEASUREMENTS AND MAIN RESULTS: In the control group, the ETT was always heavily colonized: median debris thickness was 380 microm, range 270-550 microm. In the study group, there was no colonization and no secretions in the ETT, except for three ETT that were colonized solely at the very tip. CONCLUSIONS: Silver-based coating of ETT cleaned with the MS every 6 h significantly reduces accumulation of mucus/secretion and bacterial growth within the ETT following 72 h of mechanical ventilation.     

Evaluation of continuous aspiration of subglottic secretion in an in vivo study

OBJECTIVE: Continuous aspiration of subglottic secretions (CASS) is believed to lower the incidence of ventilator-associated pneumonia. Animal studies to establish safety and efficacy of CASS have not been conducted. DESIGN: Prospective randomized animal study. SETTING: Animal-research facility at the U.S. National Institutes of Health. SUBJECTS: Twenty-two sheep. INTERVENTIONS: Sheep were randomized into three groups. In group C (control), eight sheep were kept prone, intubated with a standard endotracheal tube (ETT), and mechanically ventilated for 72 hrs with head and ETT elevated at an angle of 30 degrees. In group CASS-HU (CASS, head up), seven sheep were managed as group C and intubated with a Hi-Lo Evac, Mallinckrodt ETT (CASS suction kept at < or =20 mm Hg). In group CASS-HD (CASS, head down), seven sheep were kept prone with CASS, and the ETT and trachea were horizontal to promote spontaneous drainage of mucus from the ETT. MEASUREMENTS AND RESULTS: The lower respiratory tract in the CASS-HU group was heavily colonized in all seven sheep (median 4.6 x 10(9), range, 1.5 x 10(8) to 7.9 x 10(9) colony-forming units/g), with a reduction of lung bacterial colonization compared with the C group (p = .05). In group CASS-HD, the lower respiratory tract was not colonized in six of seven sheep. One sheep showed low levels of bacterial growth (median, 0; range, 0-2.2 x 10(5)). At autopsy, in all 14 sheep with CASS, we found tracheal mucosal injury of different degrees of severity at the level of the suction port of the ETT. CONCLUSIONS: In group CASS-HU, regardless of finding a marginal decrease of the bacterial colonization of the lower airways, there was pervasive trachea-bronchial-lung bacterial colonization. Second, there was minimal, or absent, bacterial colonization when the orientation of the CASS ETT was at, or just below, horizontal. Third, there was widespread injury to tracheal mucosa/submucosa from the use of CASS. Note that results of studies conducted in an animal model are always difficult to extrapolate to the clinical practice due to anatomical and functional differences.     

Intratracheal pulmonary ventilation keeps tracheal tubes clean without impairing mucociliary transport

Background : Intratracheal pulmonary ventilation (ITPV) is a form of tracheal gas insufflation through a reverse thrust catheter that facilitates expiration and enhances CO 2 removal. Tracheas of sheep mechanically ventilated for 3 days with gas delivered through the reverse-thrust catheter remained free of secretions, without suctioning. It was hypothesized that: 1) The expiratory flow from the lungs, combined with continuous cephalad flow from the reversethrust catheter keeps endotracheal tubes clean; and 2) tracheal mucus velocity is not impaired by ITPV. Methods : A model trachea connected to a test lung and to a ventilator, via an 8-mm endotracheal tube, was used. Inspiratory and expiratory peak flow velocities and the movement of mucus in the model trachea and in the endotracheal tube were measured during conventional mechanical ventilation and ITPV. Tracheal mucus velocity was measured radiographically, using tantalum discs as markers, in seven intubated sheep ventilated for one hour with volume-controlled ventilation, and with ITPV. One millilitre Evans Blue dye was introduced into the trachea, to visualize mucus transport into the endotracheal tube. Results : Peak expiratory flow velocity exceeded peak inspiratory flow velocity by 100% during ITPV. During volume-controlled ventilation, flow velocities were equal. During ITPV, there was slow, then rapid cephalad movement of mucus in the model trachea, 0.5 cm distal to the tip of the endotracheal tube, the velocity increasing once mucus entered the endotracheal tube. During volume-controlled ventilation, no movement of mucus was found. Baseline tracheal mucus velocity was equal during volume-controlled ventilation and ITPV. Secretions stained with Evans Blue dye entered the endotracheal tube and were rapidly expelled from within the endotracheal tubes during ITPV; only traces of mucus were found in two sheep during volume-controlled ventilation. Conclusion : The enhanced expiratory flow during ITPV expels secretions from the endotracheal tube through entraining of mucus at the tip of the endotracheal tube. Tracheal mucus velocity is not influenced by ITPV.     

Intratracheal pulmonary ventilation keeps tracheal tubes clean without impairing mucociliary transport

BACKGROUND: Intratracheal pulmonary ventilation (ITPV) is a form of tracheal gas insufflation through a reverse thrust catheter that facilitates expiration and enhances CO2 removal. Tracheas of sheep mechanically ventilated for 3 days with gas delivered through the reverse-thrust catheter remained free of secretions, without suctioning. It was hypothesized that: 1) The expiratory flow from the lungs, combined with continuous cephalad flow from the reverse-thrust catheter keeps endotracheal tubes clean; and 2) tracheal mucus velocity is not impaired by ITPV. METHODS: A model trachea connected to a test lung and to a ventilator, via an 8-mm endotracheal tube, was used. Inspiratory and expiratory peak flow velocities and the movement of mucus in the model trachea and in the endotracheal tube were measured during conventional mechanical ventilation and ITPV. Tracheal mucus velocity was measured radiographically, using tantalum discs as markers, in seven intubated sheep ventilated for one hour with volume-controlled ventilation, and with ITPV. One millilitre Evans Blue dye was introduced into the trachea, to visualize mucus transport into the endotracheal tube. RESULTS: Peak expiratory flow velocity exceeded peak inspiratory flow velocity by 100% during ITPV. During volume-controlled ventilation, flow velocities were equal. During ITPV, there was slow, then rapid cephalad movement of mucus in the model trachea, 0.5 cm distal to the tip of the endotracheal tube, the velocity increasing once mucus entered the endotracheal tube. During volume-controlled ventilation, no movement of mucus was found. Baseline tracheal mucus velocity was equal during volume-controlled ventilation and ITPV. Secretions stained with Evans Blue dye entered the endotracheal tube and were rapidly expelled from within the endotracheal tubes during ITPV; only traces of mucus were found in two sheep during volume-controlled ventilation. CONCLUSION: The enhanced expiratory flow during ITPV expels secretions from the endotracheal tube through entraining of mucus at the tip of the endotracheal tube. Tracheal mucus velocity is not influenced by ITPV.     

Physiological responses to endotracheal and oral suctioning in paediatric patients: the influence of endotracheal tube sizes and suction pressures.

OBJECTIVE: To study the influence of varying outer suction catheter (SC) diameter (OD) to inner endotracheal tube (ETT) diameter (ID) and suction pressures (SP) on heart rate (HR), respiratory rate (RR), mean arterial pressure (MAP), arterial oxygen saturation (SaO 2) and intracranial pressure (ICP) during ETT and oral suctioning. An additional aim was to define an optimal suction catheter size that would prove easy to introduce and be rapidly effective in clearing secretions with the least physiological alteration. DESIGN: Prospective study. SETTING: Paediatric intensive care unit. PATIENTS: Ventilated paediatric patients. INTERVENTION: Patients had ETT suctioning performed in a random fashion using suction catheters with SC outer diameter to inner ETT diameter of approximately 0.4, 0.7 and 0.9 using varying pressures (80, 100, 120 mmHg). Using the medium size suction catheter (OD/ID = 0.7) at 100 mmHg of suction pressure, oral suctioning was compared to ETT suctioning. MEASUREMENTS AND MAIN RESULTS: Seventeen patients were studied (age 6.5 + 5 months). All suction catheters at varying pressures resulted in similar transient alterations in HR, RR, MAP, SaO 2 and ICP following ETT suctioning. Significant changes were seen in SaO 2, HR and ICP, irrespective of the catheter diameter or suction pressure. Oral suctioning resulted in similar trends and magnitude of changes as for ETT suctioning in MAP, RR, HR, and ICP, but less change occurred in the SaO 2 (p less than 0.05). The catheters with OD/ID of 0.7 were easiest to introduce and most effective in clearing secretions. CONCLUSION: Our study suggests that: 1. Tracheal toilet using variations in OD/ID ratios and SP within limits tested resulted in similar significant adverse changes in HR, ICP and SaO 2 and similar trends in RR and MAP. 2. Based on the ease of introduction and the effectiveness of clearing secretions, a medium SC (OD/ID = 0.7) is most appropriate for infants and children. 3. Oral suctioning also results in adverse physiological changes, therefore similar precautions to those taken during tracheal suctioning should be followed for oral suctioning.     

Suctioning through a double-lumen endotracheal tube helps to prevent alveolar collapse and to preserve ventilation

Objective

Endotracheal suctioning can cause alveolar collapse and impede ventilation. One reason is the gas flow through a single-lumen endotracheal tube (ETT) provoking a gradient between airway opening and tracheal (P_tr) pressures. Separately extending the patient tubing limbs of a suitable ventilator into the trachea via a double-lumen ETT should maintain P_tr. Can this technique reduce the side effects?

Design and setting

Bench and animal studies in a university hospital laboratory.

Interventions

A lung model was ventilated via single and double-lumen ETTs. Closed-system suctioning was applied with catheters introduced into the single-lumen ETT or the expiratory lumen of the double-lumen ETT via swivel adapter. Seven anesthetized pigs (lungs lavaged) underwent three runs of ventilation and suctioning through (a, b) an 8.0-mm ID single-lumen ETT, (c) a double-lumen ETT (41Ch outer diameter, OD). In (a) the single-lumen ETT was disconnected for suctioning, in (b) and (c) ventilator mode was set to continuous positive airway pressure mode, and the ETTs remained connected.

Measurements and results

Bench: Suction through single-lumen ETTs impaired ventilation and led to strongly negative P_tr (common: ?10 to ?20 mbar); the double-lumen ETT technique maintained ventilation and pressures. Animals: Lung gas content (computed tomography, n=4) and arterial oxygen partial pressure, initially 1462±65 ml/532±76 mmHg, were significantly reduced by suctioning through single-lumen ETT: to 302±79 ml/62±6 mmHg with disconnection and to 851±211 ml/158±107 mmHg with closed suction. With double-lumen ETT they remained at 1377±95 ml/521±56 mmHg.

Conclusions

The double-lumen ETT technique minimizes side effects of suctioning by maintaining P_tr.     

Increasing positive end expiratory pressure at extubation reduces subglottic secretion aspiration in a bench‐top model

Aim: To estimate the ability of simulated tracheal suction, adjusting the positive end expiratory pressure (PEEP) settings on the ventilator or compressing a self‐inflating bag to minimize aspiration during cuff deflation and extubation in a bench‐top model. Background: During intubation, colonized secretions accumulate in the subglottic space above the endotracheal tube (ETT) cuff. Consequently, during cuff deflation and extubation, there is a risk of aspiration of the secretions. This may result in pneumonitis or pneumonia. There are a number of techniques used during cuff deflation and extubation to prevent secretion aspiration. Method: A model trachea was intubated and the proximal end of the ETT was attached to a mechanical ventilator. Ten millilitres of water was placed above the inflated cuff and then nine test protocols were implemented in a random order to simulate tracheal suction, adjusting the PEEP settings on the ventilator or compressing a self‐inflating bag. The volume of water ‘aspirated’ by the model was determined by weighing the apparatus pre‐ and post‐extubation. Statistical analysis was performed using regression analysis and heteroscedastic t tests with a Bonferroni correction. Results: The level of PEEP was negatively correlated with the volume of fluid aspirated [co‐efficient ?0·24 (99% confidence interval ?0·31 to ?0·17), R² = 0·75]. Significantly less fluid was aspirated when a PEEP of 35 cmH₂O was applied when compared with competing techniques. Discussion and conclusions: This study suggests that applying PEEP during cuff deflation and extubation is protective against aspiration. We conclude that unless there is a contraindication, the application of PEEP should be considered when extubating patients.     

Effects of a heat and moisture exchanger and a heated humidifier on respiratory mucus in patients undergoing mechanical ventilation

OBJECTIVE: To evaluate the effects of a heat and moisture exchanger and a heated humidifier on respiratory mucus and transportability by cilia and cough in patients undergoing invasive mechanical ventilation (up to 72 hrs). DESIGN: Prospective, randomized, clinical study. SETTING: General intensive care unit and university research laboratory. PATIENTS: A total of 32 consecutive patients with acute respiratory failure, who were intubated and mechanically ventilated in the intensive care unit setting, were enrolled in the study. INTERVENTIONS: Patients were randomly assigned to receive as a humidifying system a heat and moisture exchanger (HME) or heated humidified water (HHW) at the onset of mechanical ventilation (time 0). Respiratory mucus samples were collected by suction using a sterile technique at time 0, 24, 48, and 72 hrs of mechanical ventilation. MEASUREMENTS AND MAIN RESULTS: Eleven patients were excluded from this study because of either extubation or death before 72 hrs of mechanical ventilation, leaving 12 patients in the HME group and nine patients in the HHW group. Ventilatory variables including minute volume, mean airway pressure, positive end-expiratory pressure, Fio2, as well as Pao2/Fio2 ratio, fluid balance (last 6 hrs), furosemide, and inotrope administration (last 4 hrs) were recorded. In vitro mucus transportability by cilia was evaluated on the mucus-depleted frog palate model, and the results were expressed as the mucus transport rate. Cough clearance (an estimation of the interaction between the flow of air and the mucus lining the bronchial walls) was measured using a simulated cough machine, the results being expressed in millimeters. Mucus wettability was measured by the contact angle between a mucus sample drop and a flat glass surface. Mucus rheologic properties (mechanical impedance [log G*] and the ratio between viscosity and elasticity [tan delta]) were measured using a magnetic microrheometer at 1 and 100 cGy/sec deformation frequency. The two humidification groups were comparable in terms of the Acute Physiology and Chronic Health Evaluation II score, age, gender, ventilatory variables, fluid balance, use of inotropes, and furosemide. CONCLUSION: Ours results indicate that air humidification with either HME or HHW at 32 degrees C (89.6 degrees F) has similar effects on mucus rheologic properties, contact angle, and transportability by cilia in patients undergoing mechanical ventilation, except for transportability by cough, which diminished after 72 hrs of mechanical ventilation in the HME group (p = .0441).     

Endotracheal suctioning versus minimally invasive airway suctioning in intubated patients: a prospective randomised controlled trial

STUDY OBJECTIVE: Endotracheal suctioning in intubated patients is routinely applied in most ICUs but may have negative side effects. We hypothesised that on-demand minimally invasive suctioning would have fewer side effects than routine deep endotracheal suctioning, and would be comparable in duration of intubation, length of stay in the ICU, and ICU mortality. DESIGN: Randomised prospective clinical trial. SETTING: In two ICUs at University Hospital Groningen, the Netherlands. PATIENTS: Three hundred and eighty-three patients requiring endotracheal intubation for more than 24 h. INTERVENTIONS: Routine endotracheal suctioning (n=197) using a 49-cm suction catheter was compared with on-demand minimally invasive airway suctioning (n=186) using a suction catheter only 29 cm long. MEASUREMENTS AND RESULTS: No differences were found between the routine endotracheal suctioning group and the minimally invasive airway suctioning group in duration of intubation [median (range) 4 (1-75) versus 5 (1-101) days], ICU-stay [median (range) 8 (1-133) versus 7 (1-221) days], ICU mortality (15% versus 17%), and incidence of pulmonary infections (14% versus 13%). Suction-related adverse events occurred more frequently with RES interventions than with MIAS interventions; decreased saturation: 2.7% versus 2.0% (P=0.010); increased systolic blood pressure 24.5% versus 16.8% (P<0.001); increased pulse pressure rate 1.4% versus 0.9% (P=0.007); blood in mucus 3.3% versus 0.9% (P<0.001). CONCLUSIONS: This study demonstrated that minimally invasive airway suctioning in intubated ICU-patients had fewer side effects than routine deep endotracheal suctioning, without being inferior in terms of duration on intubation, length of stay, and mortality.     

Airway colonisation in long-term mechanically ventilated patients

Objective To evaluate the impact of continuous subglottic suctioning and semi-recumbent body position on bacterial colonisation of the lower respiratory tract.Design A randomised controlled trial.Setting The ten-bed medical ICU of a French university hospital.Patients Critically ill patients expected to require mechanical ventilation for more than 5 days.Interventions Patients were randomly assigned to receive either continuous suctioning of subglottic secretions and semi-recumbent body position or to receive standard care and supine position.Measurements and results Oropharyngeal and tracheal secretions were sampled daily and quantitatively cultured. All included patients were followed up from day 1 (intubation) to day 10, extubation or death. Ninety-seven samples of oropharynx and trachea were analysed (40 for the suctioning group and 57 for the control group). The median bacterial counts in trachea were 6.6 Log₁₀ CFU/ml (interquartile range, IQR, 4.4–8.3) in patients who received continuous suctioning and 5.1 Log₁₀ CFU/ml (IQR 3.6–5.5) in control patients. Most of the patients were colonised in the trachea after 1 day of mechanical ventilation (75% in the suctioning group, 80% in the control group). No significant difference was found in the daily bacterial counts in the oropharynx and in the trachea between the two groups of patients.Conclusion Tracheal colonisation in long-term mechanically ventilated ICU patients was not modified by the use of continuous subglottic suctioning and semi-recumbent body position.     

Evaluation in animals of a system to estimate tracheal pressure from the endotracheal tube cuff

Objective. Flow through an endotracheal tube (ETT) causes a pressure loss across the tube. This loss results in a difference between pressure measured at the airway and pressure measured in the trachea. This difference can lead to errors when calculating pulmonary mechanics and when setting ventilators. We have tested a method of estimating tracheal pressure from the pressure in the ETT cuff.Methods. Pressure transducers were placed in the proximal ETT connector, in the trachea, and in the ETT cuff (through the inflation port). Instantaneous periods of zero flow, detected with a flow meter, were used to calculate the slope and offset of the line relating cuff pressure to tracheal pressure. The system was tested on the bench using a ventilator and lung simulator and in 2 dogs and 5 pigs. Tests were performed at various cuff pressures, trachea diameters, ETT sizes, respiratory rates, tidal volumes, and airway obstructions. Results. In bench tests, our estimate of tracheal pressure was within –4.0±2.6% of the actual tracheal pressure (mean = standard deviation [SD]). In animal tests, our estimation of tracheal pressure was within –0.6±5%. In all bench test measurements and in 40 of 42 animal measurements, the error was less than 1 cm H₂O.Conclusions. The cuff estimation technique gives real-time, continuous, noninvasive tracheal pressure measurements in intubated animals with cuffed ETTs.     

Effect of intrapulmonary percussive ventilation on mucus clearance in duchenne muscular dystrophy patients: a preliminary report

OBJECTIVE: To determine the effects of intrapulmonary percussive ventilation (IPV) on mucus clearance in tracheostomized Duchenne muscular dystrophy patients. METHODS: We studied 8 patients, 5 of whom had mucus hypersecretion (> 30 mL/d). In a randomized, cross-over study we compared assisted mucus clearance techniques with and without IPV. There were 2 treatment sequences and each patient received 5 consecutive days of each treatment sequence, delivered 3 times a day. One sequence consisted of (1) assisted mucus clearance technique (AMCT, which involves forced expiratory technique and manual assisted cough), (2) endotracheal suctioning, (3) nebulizer administration of 5 mL of 0.9% sodium chloride solution for 5 min, (4) a second AMCT session, (5) endotracheal suctioning, (6) 45 min after the end of the nebulizer treatment a third AMCT session, (7) endotracheal suctioning. The other treatment sequence was the same except that it included IPV during the 5-min nebulizer treatment. The collected secretions were weighed. Vital capacity was measured once, before the treatments. Heart rate, respiratory rate, oxyhemoglobin saturation, end-tidal carbon dioxide, airway resistance, and peak expiratory flow were measured before and at 45 min after the treatments. Mean values were compared using analysis of variance with repeated measures. RESULTS: In patients with hypersecretion the mean +/- SD weight of the collected secretions was significantly higher with IPV (6.53 +/- 4.77 g vs 4.57 +/- 3.50 g, p = 0.01). Heart rate, respiratory rate, oxyhemoglobin saturation, end-tidal carbon dioxide, airway resistance, and peak expiratory flow did not differ statistically between the 2 treatments. CONCLUSIONS: IPV is a safe airway clearance method for tracheostomized Duchenne muscular dystrophy patients, and this preliminary study suggests that IPV increases the effectiveness of assisted mucus clearance techniques.     

Effects of expiratory rib cage compression combined with endotracheal suctioning on gas exchange in mechanically ventilated rabbits with induced atelectasis

INTRODUCTION: In Japan, expiratory rib cage compression (a chest physiotherapy technique) is frequently used with mechanically ventilated patients. It has not been determined whether rib cage compression combined with endotracheal suctioning improves oxygenation, ventilation, and mucus clearance. We evaluated the effects of rib cage compression with and without endotracheal suctioning on P(aO(2)), P(aCO(2)), dynamic compliance of the respiratory system (C(RS)), and mucus clearance in rabbits with induced atelectasis. METHODS: Anesthetized adult rabbits had an 18-gauge catheter placed into the airway, together with a tracheal tube via tracheostoma, and were mechanically ventilated. To create atelectasis, artificial mucus was infused into the airway via the catheter. Each rabbit was randomly assigned to one of 4 groups (= 7 in each): (1) control, (2) received endotracheal suctioning alone, (3) received rib cage compression alone, and (4) received both rib cage compression and endotracheal suctioning. After these interventions, for 30 min, each animal was placed supine without intervention for 120 min. RESULTS: In the groups that received rib cage compression, oxygenation, ventilation, and C.     

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).     

密闭式吸痰在重度颅脑外伤患者中的临床应用

目的观察密闭式吸痰对重度颅脑外伤患者血氧饱和度的影响。方法选择53例重度颅脑外伤患者并应用机械通气辅助呼吸的危重病人,随机分为密闭式吸痰组和开放式吸痰组,比较两组吸痰前后1min,经皮血氧饱和度（SpO2）的变化。结果开放式吸痰组吸痰后较吸痰前SpO2有明显下降,差异具有显著性（P〈0.05）,密闭式吸痰组SpO2吸痰前后比较差异无统计学意义（P〉0.05）;两组SpO2吸痰前比较差异无显著性（P〉0.05）,吸痰后开放式吸痰组SpO2低于密闭式吸痰组,差异具有显著性（P〈0.01）。结论密闭式吸痰不影响重性颅脑外伤患者氧合作用,可避免吸痰造成患者颅内压的波动,适用于重性颅脑外伤患者。     

利多卡因在神志清醒患者吸痰中的应用

目的观察利多卡因在清醒患者吸痰中的应用。方法选取本院2009年6月至2010年6月需吸痰的清醒患者83例,随机分为观察组42例,对照组41例。观察组患者在吸引前沿气管内缓慢注入2％的利多卡因0．5—1ml,2—3min后行气道内吸引;对照组采用常规方法进行气道内吸引。结果两组患者咳嗽、疼痛、躁动、气管痉挛、低氧血症、心律异常、恶心等发生情况比较,差异有统计学意义（P〈0．01）;吸痰后出血发生情况比较,差异无统计学意义（P〉0．05）;两组患者吸痰过程中、吸痰后2min、吸痰后5min的血氧饱和度检测情况比较,差异有统计学意义（P〈0．01）。结论利多卡因能够减轻清醒患者吸痰中的机体反应,降低气管的敏感性,减轻患者痛苦,值得临床推广使用。     

Ventilation patterns influence airway secretion movement

BACKGROUND: Retention of airway secretions is a common and serious problem in ventilated patients. Treating or avoiding secretion retention with mucus thinning, patient-positioning, airway suctioning, or chest or airway vibration or percussion may provide short-term benefit. METHODS: In a series of laboratory experiments with a test-lung system we examined the role of ventilator settings and lung-impedance on secretion retention and expulsion. Known quantities of a synthetic dye-stained mucus simulant with clinically relevant properties were injected into a transparent tube the diameter of an adult trachea and exposed to various mechanical-ventilation conditions. Mucus-simulant movement was measured with a photodensitometric technique and examined with image-analysis software. We tested 2 mucus-simulant viscosities and various peak flows, inspiratory/expiratory flow ratios, intrinsic positive end-expiratory pressures, ventilation waveforms, and impedance values. RESULTS: Ventilator settings that produced flow bias had a major effect on mucus movement. Expiratory flow bias associated with intrinsic positive end-expiratory pressure generated by elevated minute ventilation moved mucus toward the airway opening, whereas intrinsic positive end-expiratory pressure generated by increased airway resistance moved the mucus toward the lungs. Inter-lung transfer of mucus simulant occurred rapidly across the "carinal divider" between interconnected test lungs set to radically different compliances; the mucus moved out of the low-compliance lung and into the high-compliance lung. CONCLUSIONS: The movement of mucus simulant was influenced by the ventilation pattern and lung impedance. Flow bias obtained with ventilator settings may clear or embed mucus during mechanical ventilation.     

Increasing suction pressure during endotracheal suctioning increases the volume of suctioned secretions,but not procedure-related complications: A comparative study in open system endotracheal suctioning

ObjectivesTo compare the effect of three different suction pressures (80 mmHg, 150 mmHg, 250 mmHg) with the open system suction method in terms of the volume of secretions and complications development in intubated intensive care patients.Research methodology/designThis study was planned as a prospective, experimental, self-controlled design. The study sample included 47 patients. Data were collected using a data collection and patient follow-up form from patient records.SettingSingle adult intensive care unit in a university hospital.ResultsFifty five percent of the patients were male, 61.7% were older than 65 years and 38.32% had lung infection. The amount of suctioned secretions tended to increase significantly with increasing negative pressure and there was a significant difference between the pressures in terms of the median volume of suctioned secretions (p < 0.001). There was no significant difference between the suction pressures in terms of oxygen desaturation, hypertension rates (p > 0.05). Tachycardia, bradycardia, hypoxaemia, tracheal mucosal damage or mucosal bleeding were not observed during suctioning with three different suction pressures.ConclusionIt may be assumed that 250 mmHg suction pressure, via compliance with open system suction method related procedures, is being more effective and equally safe for secretion cleaning in comparison to the 80 and 150 mmHg suction pressures.     

Commentary: Morrow B, Futter M, Argent A. (2006). Effect of endotracheal suction on lung dynamics in mechanically-ventilated paediatric patients

Endotracheal suctioning is performed regularly in ventilated infants and children to remove obstructive secretions. The effect of suctioning on respiratory mechanics is not known. This study aimed to determine the immediate effect of endotracheal suctioning on dynamic lung compliance, tidal volume and airway resistance in mechanically ventilated paediatric patients by means of a prospective observational clinical study. Lung mechanics were recorded for 5 min before and 5 min after a standardized suctioning procedure in 78 patients intubated with endotracheal tubes of ≤4·0 mm internal diameter. Twenty‐four patients with endotracheal tube leaks ≥20% were excluded from analysis. There was a significant overall decrease in dynamic compliance (p < 0·001) and mechanical expired tidal volume (p = 0·03) following suctioning with no change in the percentage of endotracheal tube leak (p = 0·41). The change in dynamic compliance was directly related to both endotracheal tube and catheter sizes. There was no significant change in expiratory or inspiratory airway resistance following suctioning (p > 0·05). Although most of the patients (68·5%) experienced a drop in dynamic compliance following suctioning, dynamic compliance increased in 31·5% of patients after the procedure. This study demonstrates that endotracheal suctioning frequently causes an immediate drop in dynamic compliance and expired tidal volume in ventilated children with variable lung pathology, intubated with small endotracheal tubes, probably indicating loss of lung volume caused by the suctioning procedure. There is no evidence that suctioning reduces airway resistance. Abstract reprinted from the Australian Journal of Physiotherapy volume 52, Morrow B et al., ‘Effect of endotracheal suction on lung dynamics in mechanically‐ventilated paediatric patients’, pages 121–126. © 2006, reproduced with permission from the Australian Physiotherapy Association.