High Volume Low Pressure Research Articles

Carbon Micron-size Content Dependency in Epoxy/Carbon Composite Coated onto SPCC Plate for Automotive Bodies Protection

Conventional epoxy coating for surface metal corrosion protection reported many unsolved technical problems. Adding filler in the epoxy could enhance the promising properties of the composite coating. Our work describes in detail the synthesizing and characterizing epoxy/carbon composite coating. Epoxy was mixed with thinner high gloss (HG) and hardener and stirred using a stirrer apparatus. After blending, various carbons were added (1 wt. %, 3 wt. %, and 5 wt. %) and then appropriately stirred. The different mixture composite was coated onto the steel plate cold rolled coiled (SPCC) plate using high-volume low-pressure (HVLP) in two passes. Various characterizations were performed, including crystallographic orientation, Infra-Red (IR)-spectra, surface morphology, thickness, hydrophobicity, hardness, and corrosion using X-ray diffraction (XRD), Fourier transform infrared (FTIR), Scanning electron microscopy (SEM), portable dry film coating thickness (DFT), digital camera, Vickers microhardness tester, and Potentiostat, respectively. More carbon micron-sized content led to elevate the peak intensity, surface bumpiness, and hydrophobicity. The uppermost external bumpiness and hydrophobicity values are 23.51 µm and 101◦. Hardness depends on carbon content and more carbon leads to an increase in the hardness of the composited coating. The highest average Vickers hardness value is 28.24 HV. The coating thickness influenced the corrosion rate, more coating thickness promoted lesser corrosion rate. The highest coating thickness (60.8 µm) promoted a corrosion rate of around 5.65×10−4 mmpy.

Particulate removal characteristics of commercial-scale DeNOx catalyst cartridge coupled filter bags

The commercial-scale DeNOx catalyst cartridge coupled with filter bag have been developed for the removal of fine particulate matter and nitrogen oxides (NOx) in flue gases. The DeNOx catalyst cartridge coupled filter bag is made up of a microporous PTFE (polytetrafluoroethylene) membrane/impregnated polyimide fiber needle-punched pleated filter bag designed for the removal of ultrafine particulates, along with a pellet selective catalytic reduction catalyst-filled cartridge for the removal of NOx. V2O5-MoO3/TiO2 catalyst was used as the DeNOx catalyst. The distribution of cleaning air velocity inside the DeNOx catalyst cartridge-coupled filter bag, which is injected with compressed air from the high-volume low-pressure (HVLP) pulse injector to remove the deposited dust cake from the surface of the filter bags during pulse-jet cleaning, was confirmed using computational fluid dynamics (CFD). The particulate removal and dust cake dislodgement characteristics of the DeNOx catalyst cartridge coupled filter bag were tested in a commercial-scale filter bag test unit under conditions simulating fossil fuel combustion flue gas. The commercial-scale DeNOx catalyst cartridge coupled filter bag was 165 mm in diameter, 2000 mm in total length, and contained approximately 12 kg of DeNOx catalyst- filled cartridges. Nine commercial-scale DeNOx catalyst cartridge coupled filter bags were installed in the commercial-scale filter test unit. The experimental conditions were as follows: flue gas temperature 200 °C, flue gas flow rate 3000Nm3/h, NO, SO2, and particulate concentration in inflow flue gas 200 ppm, 7 ppm, and 5000 mg/Nm3 respectively, resulting in different values of filtration velocities. The efficiency of bag cleaning and intervals, overall collection efficiency, fractional efficiency, and filter quality were investigated. The average bag cleaning efficiency and overall collection efficiency were 95.5%, 91.5%, and 83.3% at filtration velocities of 0.8, 1.0 and 1.2 m/min, respectively. The corresponding values for overall collection efficiency were 99.9%, 99.5%, and 98.2%. So, both bag cleaning efficiency and overall collection efficiency decreased with increased filtration velocity. The present study confirmed that DeNOx catalyst cartridge coupled filter bags have relatively higher bag cleaning efficiency, collection efficiency, and filter quality for challenging fossil fuel combustion flue gas. Particularly, the fractional efficiency for micron-sized particles was considerably higher at lower filtration velocities.

INDICATIONS AND COMPLICATIONS OF TRACHEOSTOMY AT A TERTIARY CARE INSTITUTE: A PROSPECTIVE AND OBSERVATIONAL STUDY

Objective: The aim of the present study was to present an analysis of indications and complications of tracheostomy in tracheostomized patients. Methods: This was a single center, hospital-based prospective, non-randomized, and non-comparative study involving 60 tracheostomized patients carried out from February 2021 to March 2022 at Geetanjali Medical College and Hospital, Udaipur, India. Results: Out of 60 tracheostomies performed most common indications were Laryngo-tracheal trauma (26.7%), organophosphorus poisoning (25%), malignancy of Larynx (11.67%), post-intubation stenosis (6.7%), bilateral abductor paralysis (6.7%), head injury (6.7%), meningitis (5%), acute laryngo-traheo-bronchitis (3.33%), hypoxic-ischemic-encephalopathy (3.33%), cerebrovascular accidents (1.67%), faucial diptheria (1.67%), and GB syndrome (1.67%). Out of 60 tracheostomies performed, 18 complications were encountered. The most common complication was granulations of tracheostoma which occurred in 5 cases (8.3%), three cases of tube occlusion (5%), three cases had difficult decannulation (5%), three cases developed infection of stoma (5%), two cases developed surgical emphysema (3.3%), one case of tracheostomy scar hypertrophy (1.6%), and one case developed tracheal stenosis (1.6%). Conclusion: Tracheostomy is the procedure of choice especially in cases. Where it is needed to provide prolonged positive pressure ventilation and tracheobronchial toilet. Thorough anatomical knowledge of trachea and adjacent structures, skill of surgeon, sterile technique, meticulous surgery, use of high-volume low pressure cuffed Portex tracheostomy tubes, and good bedside tracheostomy care results in minimal complications. Complications of tracheostomy are largely preventable.

Impact of Low-Volume, Low-Pressure Tracheostomy Cuffs on Acute Mucosal Injury in Swine.

Tapered low-volume, low-pressure (LVLP) cuffs have been introduced to improve sealing and reduce injury from tracheostomy and endotracheal intubation compared to traditional cylindrical high-volume, low-pressure (HVLP) cuffs. The objective of this study is to develop a swine model of tracheostomy injury and to compare live tissue response following LVLP and HVLP tracheostomy placement. In vivo animal study. Academic institution. Swine underwent tracheostomy followed by placement of LVLP and HVLP tracheostomy cuffs at 30 cm H2O. After 24 and 48 hours, tracheal specimens underwent histopathological analysis including cilia, lamina propria and epithelial thickness, and mucosal injury score. In all cuff contact areas, mean epithelial thickness for both tracheostomy cohorts was decreased compared to control epithelium at 24 and 48 hours (P < .01). HVLP proximal epithelium thickness was decreased at 24 and 48 hours relative to LVLP sections (P < .05). Lamina propria thickness in proximal LVLP sections was less than HVLP sections at 24 hours and 48 hours (P < .05). Mucosal injury score at areas of cuff contact was increased in tracheostomy cohorts relative to controls (P < .001), with HVLP injury score greater than LVLP at the proximal cuff (P < .05). In a swine model, tracheostomy resulted in increased mucosal injury compared to normal tracheal mucosa. LVLP cuffs resulted in less injury than HVLP cuffs, with reduced mucosal inflammation and improved health of epithelium and lamina propria. The wider proximal LVLP cuff demonstrated improved mucosal health compared to the HVLP cylindrical cuff.

Endotracheal Tube Size and Post-Operative Sore Throat in Women

Aim: To determine the proportion of women with postoperative sore throat an hour after elective surgery in women intubated with a size 6 endotracheal tube versus size 7 endotracheal tube. Study design: Randomized controlled trial Place and duration of study: Department of Anesthesiology, The Indus Hospital, Karachi from 22-09-2016 to 2109-2017. Methodology: Patients were divided two equal groups through randomization i.e. endotracheal tube size 6 versus endotracheal tube size 7. Prior to intubation the endotracheal tube is to be lubricated with normal saline. In group ETT 6, trachea intubated with a high volume low pressure endotracheal tube with internal diameter 6.0 and in group ETT 7 with a 7.0 diameter tube respectively. Immediately after intubation the endotracheal tube was verified by a five-point auscultation technique and the cuff inflated with room air until no air leakage could be heard. No humidifiers or moisture exchangers were used. Results: The mean age of ETT 6 and ETT 7 group was 34.36±9.46 and37.34±10.96 years respectively. The mean duration of surgery in ETT 6 and ETT 7 group was 117.70±30.57 and 125.17±55.0 minutes respectively. When both groups were postoperative sore throat was noted in 38 (59.4%) in ETT 6 group whereas 62 (96.9%) noted in ETT7 group (p=0.0001). Conclusion: Highly significant difference was found in postoperative sore throat between the group endotracheal tube size 6 in comparison to the group endotracheal tube size 7. Keywords: Endotracheal intubation, Sore throat, Hoarseness, Postoperative complications, Elective surgery

Changes in the cuff pressure in neonates in the absence of nitrous oxide.

Changes in the pressure of cuffed neonatal size tracheal tubes (TT) during anaesthesia without nitrous oxide are not well described. We determined whether the cuff pressure changes over time in neonates under general anaesthesia without nitrous oxide. The airways of thirty neonates were secured with a high volume low pressure cuffed TT for meningocele surgery. The cuff was manually inflated until there was no audible leak and maintained at 10-15 cm H2O throughout by monitoring the pressure continuously with both a manometer and a pressure transducer. At baseline, the cuff pressure was assessed in the supine and then prone positions. During surgery, if the pressure exceeded 15 cm H2O, the cuff was deflated to < 15 cm H2O and if it was < 10 cm H2O, the cuff was inflated to 10-15 cm H2O. The time interval between corrections and the number of corrections were recorded. The cuff pressures in 18 neonates (60%) required correction during surgery. The cuff pressure exceeded 15 cm H2O in nine neonates (30%) and was corrected. The cuff pressures in 13 neonates were less than 10 cm H2O and required correction. The gender, weight, height, and duration of anaesthesia did not differ significantly between neonates who required correction of the cuff pressure and those who did not. Mean cuff pressures were similar at 15, 45, and 75 minutes of anaesthesia. In 60% of neonates undergoing surgery in the prone position under general anaesthesia without nitrous oxide, the cuff pressure exceeded 15 cm H2O. In such cases, cuff pressure should be monitored continuously throughout the surgery.

Carbon nitride materials: impact of synthetic method on photocatalysis and immobilization for photocatalytic pollutant degradation

Different synthesis routes for carbon nitride materials (CN) and the resulting products were compared to study the photocatalytic activity (pollutant degradation) in dependence on structure and properties. The CN materials were synthesized by thermal decomposition of dicyandiamide in air and under argon as well as in sealed ampoules with or without the use of a salt melt. The as-prepared materials were characterized by IR spectroscopy, nitrogen adsorption measurement, solid-state NMR spectroscopy, diffuse reflectance UV–Vis spectroscopy, elemental analysis and powder X-ray diffraction (PXRD). The surface polarity of the CN materials was estimated by adsorption of the dicyano-bis(1,10-phenanthroline)-iron(II) complex, which allows an evaluation of the degree of condensation. The CN materials were tested with regard to the photocatalytic degradation of rhodamine B (RhB). It is shown that the photocatalytic activity increases with higher surface polarity. Promising CN materials with high RhB degradation of 85% within 25 min and high surface polarity of 0.89 were selected for an immobilization approach to obtain coatings on a silicone substrate using a high-volume low-pressure (HVLP) spray coating technique. To study the photocatalytic activity of the catalyst coatings, the degradation rates of an aqueous RhB solution and solutions of organic pollutants such as triclosan and ethinyl estradiol were examined. Pollutants are decomposed with up to 63% of the initial concentration. Xenon lamps and different LEDs were used as light sources for comparison. Particularly high degradation efficiencies were obtained using LEDs, and the degradation rates are increased by adjusting the emission spectrum of the lamp to the pollutant and absorption edge of the catalyst, which results in a 40 times higher degradation efficiencies of LEDs compared to a Xe lamp.Graphical abstract

Corrosion Resistance, Dielectric and Thermal Resistance Properties of Hybrid Polyurethane/Carbon/Nano-Zinc Oxide

Hybrid materials polyurethane films were prepared with different content of carbon, and carbon/zinc oxide as filler components in polyurethane matrix. The films were deposited on low carbon steel plate using high volume low pressure (HVLP) method. To observe corrosion resistance of the films, the samples were examined by salt spray method. Dielectric properties were obtained by resistivity valued method. Thermal resistance was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) used to see functional groups and phase composition of carbon and zinc oxide (ZnO) in polyurethane matrix. After ZnO and carbon addition, we observe changes in surface morphology and more resistant to corrosion. Dielectric test showed that only carbon dispersed in polyurethane matrix have higher dielectric value at higher frequency. TGA and DSC confirmed composites with carbon and ZnO as filler that has highest temperature decomposition.

Intraoperative airway cuff pressure monitoring: are we doing it right?

Background: Insertion of endotracheal tubes (ETT) and supra-glottic airway devices (SGA) are common practice amongst anaesthesiologists when administering general anaesthesia to facilitate numerous surgical procedures. In an era where quality of patient care and patient safety takes precedence, monitoring of intraoperative cuff pressure of an airway device remains an essential component in anaesthetic practice. Methods: Data was collected through a single page questionnaire from postgraduate trainees in anaesthesiology involved in administering general anaesthesia for elective surgical procedures over a three- month period at the National Hospital of Sri Lanka. Study population included all patients undergoing elective surgical procedures requiring an endotracheal tube (ETT- high volume low pressure cuff) or a supra-glottic airway (SGA) device to facilitate ventilation under general anaesthesia. Data was analysed using SPSS version 22.0 and was expressed as median, inter-quartile range [IQR], frequency, percentage and 95% confidence interval (CI) where appropriate. Correlation test was used to determine the relationship between cuff pressure and size of airway device. A non-parametric test was used to measure the significance between various carrier gas combinations and cuff pressure values for both ETT and SGA devices. Results: 196 completed questionnaires were received over a three-month period. Mean age of the patients were 44.1 years and 64.8% were females. Majority (53.6%) were ASA (American Society of Anaesthesiologists) grade I. ETT were used in 82.7% and SGA devices were used in 13.8% of cases. ETT’s were used for laparotomies/laparoscopic procedures in 32.7% followed by 22.2% in gynaecological surgeries and 17.9% in thyroid and related surgery. SGA devices were mostly used for gynaecological procedures (40.7%). Theatre supporting staff was responsible for the initial cuff inflation in 83.2%. During the initial cuff pressure measurement 58.6% of endotracheal tubes had pressures within the recommended level (20-30cmH 2 O). 33.3% had cuff pressures of >30cmH 2 O while 8% had cuff pressures of 2 O. In contrast to the above findings, the recommended cuff pressure values for SGA devices was achieved only in 29.6% and in 37% the cuff pressures were more than 70cmH 2 O which was alarming. 33.3% had cuff pressure values less than recommended. Conclusion and Recommendations: It is evident that cuff pressure values in both endotracheal tubes and supra-glottic devices were not optimal and it was more so with the latter. Adherence to current evidence-based recommendations to ensure patient safety is vital in anaesthetic practice. To overcome the above problem, cuff pressure must be monitored at the commencement of surgery and at hourly intervals during general anaesthesia, which will identify under or over-inflation of the cuff and minimize related complications. Similarly, a sign-post to remind the anaesthetist, “Have you checked the cuff pressure today?” should be displayed in all operating theatres next to the airway trolley to avoid failure to reach standards.

Tracheostomy: Experience at Tertiary Hospital.

An attempt was made to find indications of tracheostomy procedure and its complications in the modern era of medicine with refined surgical techniques at a tertiary hospital. A retrospective study of 240 patients, who had undergone tracheostomy, was done during the period from January 2013 to April 2017 at Govt. Medical College Hospital. Various details of all participants such as age and sex of patients, detailed history of the current disease, and detailed information about tracheostomy and complications were recorded. In the present study, the most common indication for tracheostomy was prolonged ventilation due to Organophosphorus poisoning and Snake bite. The complication rate for tracheostomy procedure was 11.5%. The most common complication was tubal occlusion (7.5%) followed by Granulations around stoma (2.5%), Tracheal stenosis (1.25%), tracheoesophageal fistula (0.4%). No death was occurred during the tracheostomy procedure. The morbidity and mortality due to tracheostomy are reduced definitely. Tracheostomy Complications can be prevented by refined surgical techniques, use of high volume low pressure cuffed tracheostomy tubes and attentive post-operative nursing care. Yet complications of tracheomalacia and tracheal stenosis call for further improvement.

Thermal behaviour and corrosion resistance of nano-ZnO/polyurethane film

Hybrid materials Nano-ZnO/polyurethane film was prepared with different zinc oxide (ZnO) content in polyurethane as a matrix. The film was deposited on low carbon steel plate using high volume low pressure (HVLP) method. To observe thermal behaviour of the film, the sample was investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Fourier transform infrared spectroscopy (FTIR) was used to see whether any chemical reaction of ZnO in polyurethane occured. TGA and FTIR results showed that the decomposition temperature shifted to a higher point and the chemical reaction of zinc oxide in polyurethane occurred. The surface morphology changed and the corrosion resistance increased with an increase of ZnO content

Application of low damage endotracheal intubation in patients undergoing extra long-term endotracheal intubation: a case report

To approach the effect of low damage endotracheal intubation on reducing the occurrence of cuff-related intubation complication and prolonging the intubation time. On January 7th, 2015, 1 patient with respiratory failure after subarachnoid hemorrhage were admitted to Huludao Central Hospital. Immediate endotracheal intubation and ventilator assisted ventilation were performed. When the trachea was difficult to be removed in a short time, and tracheotomy was refused, a low damage endotracheal intubation was used for a long term. On the basis of the original high volume low pressure cuff, this tube was designed for inner cuff, the hole was allowed in the inner cuff to connect with the tube. During the period of ventilation, the cuff pressure changed with airway pressure automatically, therefore it would reduce the compression injury of tracheal mucosa, improve the tolerance of the patients, and prolong the intubation time. The patient was removed from the tube on October 12th, 2015 with an intubation day of 279, the intubation-related complications and severe aspiration pneumonia had not been observed during the application of low damage endotracheal intubation. Design of this intubation ensured the cuff pressure changes with airway pressure, therefore, it could effectively avoid the cuff pressure become too high, and reduce the occurrence of intubation-related complication. This low damage endotracheal had an evident superiority in the aspects of cuff management. It has a better practical significance, especially for patients with long intubation time.

Urinary Biomarkers for Bladder Outlet Obstruction

Purpose of Review Lower urinary tract symptoms (LUTS) in elderly men are often caused by bladder outlet obstruction (BOO) as a result of benign prostatic hyperplasia (BPH). The consequences of BOO-induced LUTS include the low compliance high pressure bladder as well as the high volume low pressure bladder with loss of bladder function.

Comparison of the Effect on the Cuff Pressure of the Endotracheal Tubes Following Cuff Inflation with Air and With Nitrous Oxide – Oxygen during General Anaesthesia - A Prospective, Randomised Study

Background and aims: During general anaesthesia cuffed endotracheal tubes are used to provide airway seal and prevent aspiration. But it has been observed that use of nitrous oxide oxygen for ventilation during anaesthesia leads to rise in intracuff pressure which can be transmitted to the wall of trachea leading to complications. In this study we compared the effect on cuff pressure of Portex endotracheal tubes( high volume low pressure cuffs) and Armoured endotracheal tubes( low volume high pressure cuffs) when the cuffs were inflated with air and with nitrous oxide- oxygen mixture during general anaesthesia using nitrous oxide oxygen. Method:After institutional ethics committee approval 180 patients aged 18 -60 years of ASA status I & IIposted for elective surgeries were randomly allocated in four groups of 45 each. After taking consent and intravenous access general anaesthesia was given with endotracheal intubation. Group A1- Portexendotracheal tube cuff inflated with air. Group A2- Portex endotracheal tube cuff inflated with nitrous oxide- oxygen mixture. Group B1- Armoured endotracheal tube cuff inflated with air.Group B2- Armoured endotracheal tube cuff inflated with nitrous oxide- oxygen mixture. Controlled ventilation was done with nitrous oxide oxygen during the anaesthesia. Endotracheal tube cuff pressure was measured at inflation and at every 30 minutes interval till 90 minutes. Postoperatively patients were observed for any complications such as sore throat, difficulty in swallowing, hoarseness of voice, etc. Results: It was observed that the intracuff pressure in both the high volume low pressure and the low volume high pressure cuffed endotracheal tubes rises with time when the cuffs are inflated with air. The rise was not significant when nitrous oxide - oxygen was used for inflating the cuff in both the groups. Regardless of the type of inflating medium used for cuff inflation the incidence of complications was high in low volume high pressure cuffed endotracheal tubes as compared to high volume low pressure cuffed endotracheal tubes.

Evaluation of the Effect of Tracheal Tube Orientation on Success of Intubation through Intubating Laryngeal Mask Airway.

Polyvinyl Chloride Endotracheal Tube (PVC ETT) can be used as an alternative to Fastrach Silicone Wire-Reinforced Tube (FTST) for intubation through Intubating Laryngeal Mask Airway (ILMA) as the latter is expensive and has low volume high pressure cuff. To evaluate the effects of orientation of PVC ETT (normal curve and reverse curve) on the success of intubation through ILMA, haemodynamic response and postoperative sore throat. Sixty healthy adult patients of ASA physical status I & II scheduled for elective surgery under general anaesthesia requiring endotracheal intubation were randomly divided into two groups. In Normal (N) group (n=30), the tracheal tube was inserted with its natural curve following the 90° curvature of ILMA. In Reverse (R) group (n=30), the tracheal tube was inserted with its natural curve directed opposite to the curvature of ILMA. The time taken to intubate, number of attempts, and maneuvers required for successful endotracheal intubation along with haemodynamics and oxygen saturation were noted. Postoperative sore throat was evaluated using a Verbal Analogue Scale (VAS) (0-10). Qualitative data was analysed by Chi-Square test and Fisher's exact test. Quantitative data was analysed by unpaired t-test and Mann-Whitney test. Placement of ILMA was successful in all patients. Total Intubation Time (mean±SD) in Group N was 12.53±1.78 seconds and in Group R was 11.97±1.33 seconds (p>0.05). Tracheal intubation through ILMA was successful in all patients. First attempt success rate in R Group (26 patients, 86.7%) was higher than N Group (22 patients, 73.3%) (p>0.05). Four patients (13.3%) in R Group and 8 patients (26.7%) in N Group required 2nd step of Chandy's maneuver during second attempt for successful intubation. Incidence of sore throat 6 hours postoperatively was statistically significant (median value 2.00 in N Group vs. 0.00 in R Group) between two groups. PVC ETT with reverse orientation increases first attempt success rate of intubation through ILMA with less immediate postoperative laryngeal morbidity.

Does Endotracheal Tube Design Affect Cuff Seal, Safety and Subglottic Suction Performance: An in-vitro study?

Introduction: Ideally endotracheal tubes (ETT) should protect the airways without causing pressure induced tissue damage. Traditionally, the addition of a tracheal cuff was heralded as seal against aspiration. This type of ETT utilized a low volume high pressure cuff which caused tracheal damage such as stenosis and malacia. The next development in ETT design was the high volume low pressure cuffs intended to protect the airways while reducing tissue damage. Although reducing damage, the new cuff did not reliably protect the airways. Microaspiration still remains a serious complication of intubation. A taper shaped cuff design was recently introduced to prevent microaspiration without causing tracheal damage. Concerns were raised regarding the contact area and the resultant pressure against the tracheal wall of the taper shaped cuff. Another innovation introduced to prevent microaspiration is subglottic suction present in the tube design. Therefore, the aim of this paper is to evaluate cuff seal performance, cuff safety and intrinsic suction efficiency of current commercially available ETT. Methods: Three separate studies evaluated these areas of interest. Cuff seal performance was evaluated using an approved in vitro test fixture mimicking the human trachea. We investigated the cuff seal performance of 7 endotracheal tubes with different cuff designs and identical tracheal tube size using water as the medium. Three different size tubes from 3 different manufacturers were tested to determine subglottic suction efficiency and cuff sealing performance using the same in vitro test fixture. In a similar fixture a pressure sensitive array was mounted to compare the surface pressure of a standard barrel shaped cuff to the taper shaped cuff. The array design allowed for the pressure profile of the cuff to be mapped where it contacted the cylinder wall. In all tests the cuff pressures were maintained at 25 cm H_2O according to manufacturer's recommendations. Results: The sealing performance varied between the tube manufacturers with TaperGuard (TG) showing the lowest leak at .6 g/5minutes and Kimberly Clark Micro cuff (KCmc) with the highest 59.2 g/5 minutes. In terms of suction efficiency Teleflex ISIS (ISIS) had the best suction performance (.2-5.3ml/sec) at all viscosities and Portex (SACETT) (.3-2.9 ml/min) was the lowest. When comparing surface force the taper shaped cuff was less compared to the barrel shaped cuff. Conclusions: Performance in all areas tested ETTs varied considerably in terms of sealing and suction efficiency. However, the taper shaped cuff demonstrated the least surface pressure and best sealing.

Cuffed endotracheal tubes for neonates and young infants: a comprehensive review

Traditionally, uncuffed endotracheal tubes (ETTs) have been used for artificial ventilation of infants and children. More recently, newer designed high-volume low-pressure (HVLP) cuffed ETTs are being used with increasing frequency...

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.

Tracheal Resection and Anastomosis for Postintubation Tracheal Stenosis

Introduction: Tracheal stenosis is one of the dreaded complication of tracheal intubation. Tracheal resection and anastomosis is an established definitive treatment for stenosis more than one cm. Here, we present a case of postintubation tracheal stenosis managed by resection and anastomosis, first of its kind in our centre.&#x0D; Case Report: We present a case of 26-year female who underwent tracheal intubation during her treatment of tubercular meningitis. Two weeks later, she returned with respiratory difficulty. A diagnosis of post-intubation tracheal stenosis was made. Tracheal resection and anastomosis was done. Recovery was uneventful and she was discharged on 14th post-operative day.&#x0D; Conclusion: Post-intubation tracheal stenosis is still a dreaded complication even after the introduction of high volume low pressure cuff. They can be successfully managed. Care personnel in intensive care unit (ICU) should perform to prevent this complication.

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.