Endotracheal Cannula Research Articles

Identification of a Novel Target Implicated in Chronic Obstructive Sleep Apnea-Related Atrial Fibrillation by Integrative Analysis of Transcriptome and Proteome.

This study aimed to identify a newly identified target involved in atrial fibrillation (AF) linked to chronic obstructive sleep apnea (COSA) through an integrative analysis of transcriptome and proteome. Fifteen beagle canines were randomly assigned to three groups: control (CON), obstructive sleep apnea (OSA), and OSA with superior left ganglionated plexi ablation (OSA+GP). A COSA model was established by intermittently obstructing the endotracheal cannula during exhalation for 12 weeks. Left parasternal thoracotomy through the fourth intercostal space allowed for superior left ganglionated plexi (SLGP) ablation. In vivo open-chest electrophysiological programmed stimulation was performed to assess AF inducibility. Histological, transcriptomic, and proteomic analyses were conducted on atrial samples. After 12 weeks, the OSA group exhibited increased AF inducibility and longer AF durations compared to the CON group. Integrated transcriptomic and proteomic analyses identified 2422 differentially expressed genes (DEGs) and 1194 differentially expressed proteins (DEPs) between OSA and CON groups, as well as between OSA+GP and OSA groups (1850 DEGs and 1418 DEPs). The analysis revealed that differentially regulated DEGs were primarily enriched in mitochondrial biological processes in the CON-vs.-OSA and OSA-vs.-GP comparisons. Notably, the key regulatory molecule GSTZ1 was activated in OSA and inhibited by GP ablation. These findings suggest that GSTZ1 may play a pivotal role in mitochondrial damage, triggering AF substrate formation, and increasing susceptibility to AF in the context of COSA.

Intervention to severe lower trachea obstruction supported by extracorporeal membrane oxygenation in a human immunodeficiency virus patient: A case report and literature review

Here we reported a case, male, 33 years old, diagnosed with human immunodeficiency virus (HIV) infection 5 months ago, but he didn’t take antiretroviral drugs regularly. He was admitted to intensive care unit emergently due to hypoxemia, hypercapnia, and hypotension. CT showed severe lower trachea obstruction caused by soft tissue. After rapid bedside assessment, the patient was considered to need endotracheal operation, but he couldn‘t tolerate intubation and mechanical ventilation. Extracorporeal membrane oxygenation (ECMO) was used. Hemodynamics improved significantly along with rehydration and low-dose vasoactive drugs. Subsequently, the patient underwent rigid bronchoscopy, airway tumor resection and Y-type silicone stent implantation. Postoperatively protective endotracheal intubation and mechanical ventilation was followed. ECMO was weaned off after the operation, and endotracheal cannula was removed 6 h later. The pathological examination of excisional tissue showed lung squamous cell carcinoma. Finally, the patient was discharged safely and went to local hospital for further treatment. From this case, we conclude that ECMO could play a key role for those who need endotracheal surgery while cannot endure conventional intubation and mechanical ventilation.

Cuffed endotracheal tube as a cardiopulmonary bypass venous return cannula.

Cuffed endotracheal tube as a cardiopulmonary bypass venous return cannula.

Risk factors and outcomes associated with vancomycin-resistant Enterococcus faecium and ampicillin-resistant Enterococcus faecalis bacteraemia: A 10-year study in a tertiary-care centre in Mexico City

ObjectivesWe sought to identify risk factors associated with vancomycin-resistant Enterococcus faecium (VRE) and ampicillin-resistant Enterococcus faecalis (ARE) bacteraemia, predictors of 30-day mortality, and 90-day recurrence-free survival according to resistance. MethodsWe evaluated clinical records of patients with E. faecalis and E. faecium bacteraemia (2007–2017). We performed bivariate and multivariate logistic regression analyses to identify factors associated with VRE and ARE bacteraemia and predictors of 30-day mortality. A Kaplan–Meier estimate of 90-day recurrence-free survival was done. ResultsWe identified 192 and 147 E. faecium and E. faecalis bacteraemia episodes, respectively, of which 55.7% of E. faecium were VRE (94% vanA) and 12.2% of E. faecalis were ARE. Factors related to VRE bacteraemia were previous hospitalisation (aOR, 80.18, 95% CI 1.81–634), history of central venous catheter (aOR, 11.15, 95% CI 2.48–50.2) and endotracheal cannula use (aOR, 17.91, 95% CI 1.22–262.82). There was higher attributable mortality to VRE (28%, 95% CI 14–68%; P < 0.001) and ARE (10%, 95% CI 0.1–36%; P = 0.58) compared with their susceptible counterparts. APACHE II (aOR, 1.45, 95% CI 1.26–1.66) and history of chemotherapy (aOR, 3.52, 95% CI 1.09–11.39) were predictors of E. faecium bacteraemia 30-day mortality. We could not recognise any factor related to ARE bacteraemia or E. faecalis 30-day mortality. ConclusionHistory of hospitalisation and invasive device use were related to VRE bacteraemia. APACHE II and history of chemotherapy were predictors of mortality. We could not identify factors related to ARE or predictors of mortality.

Lung Collapse during Mini-Thoracotomy Reduces Penetration of Cefuroxime to the Tissue: Interstitial Microdialysis Study in Animal Models.

Background: Single-lung ventilation facilitates surgical exposure during minimally invasive cardiac surgery. However, a deeper knowledge of antibiotic distribution within a collapsed lung is necessary for effective antibiotic prophylaxis of pneumonia. Patients and Methods: The pharmacokinetics/pharmacodynamics (PK/PD) of cefuroxime were compared between the plasma and interstitial fluid (ISF) of collapsed and ventilated lungs in 10 anesthetized pigs, which were ventilated through a double-lumen endotracheal cannula. Cefuroxime (20 mg/kg) was administered in single 30-minute intravenous infusion. Samples of blood and lung microdialysate were collected until six hours post-dose. Ultrafiltration, in vivo retrodialysis, and high-performance liquid chromatography-tandem mass spectrometry were used to determine plasma and ISF concentrations of free drug. The concentrations were examined with non-compartmental analysis and compartmental modeling. Results: The concentration of free cefuroxime in ISF was lower in the non-ventilated lung than the ventilated one, evidenced by a lung penetration factor of 47% versus 63% (p < 0.05), the ratio between maximum concentrations (65%, p < 0.05), and the ratio between the areas under the concentration-time curve (78%, p = 0.12). The time needed to reach a minimum inhibitory concentration (MIC) was 30%-40% longer for a collapsed lung than for a ventilated one. In addition, a delay of 10-40 minutes was observed for lung ISF compared with plasma. The mean residence time values (ISF collapsed lung > ISF ventilated lung > plasma) could explain the absence of practically important differences in the time interval with the concentration of cefuroxime exceeding the MICs of sensitive strains (≤4 mg/L). Conclusion: The concentration of cefuroxime in the ISF of a collapsed porcine lung is lower than in a ventilated one; furthermore, its equilibration with plasma is delayed. Administration of the first cefuroxime dose earlier or at a higher rate may be warranted, as well as dose intensification of the perioperative prophylaxis of pneumonia caused by pathogens with higher MICs.

Walking the line between benefit and harm from tracheostomy in COVID-19

Walking the line between benefit and harm from tracheostomy in COVID-19

Weaning from tracheostomy in subjects undergoing pulmonary rehabilitation

Background: Weaning from tracheostomy has implications in management, quality of life, and costs of ventilated patients. Furthermore, endotracheal cannula removing needs further studies. Aim of this study was the validation of a protocol for weaning from tracheostomy and evaluation of predictor factors of decannulation.&#x0D; Methods: Medical records of 48 patients were retrospectively evaluated. Patients were decannulated in agreement with a decannulation protocol based on the evaluation of clinical stability, expiratory muscle strength, presence of tracheal stenosis/granulomas, deglutition function, partial pressure of CO2, and PaO2/FiO2 ratio. These variables, together with underlying disease, blood gas analysis parameters, time elapsed with cannula, comordibity, Barthel index, and the condition of ventilation, were evaluated in a logistic model as predictors of decannulation.&#x0D; Results: 63 % of patients were successfully decannulated in agreement with our protocol and no one needed to be re-cannulated. Three variables were significantly associated with the decannulation: no pulmonary underlying diseases (OR = 7.12; 95 % CI 1.2–42.2), no mechanical ventilation (OR = 9.55; 95 % CI 2.1–44.2) and period of tracheostomy ≤10 weeks (OR = 6.5; 95 % CI 1.6–27.5).&#x0D; Conclusions: The positive course of decannulated patients supports the suitability of the weaning protocol we propose here. The strong predictive role of three clinical variables gives premise for new studies testing simpler decannulation protocols.

573. Enterococcal Bacteremia in a Tertiary Care Center in Mexico: A Retrospective Analysis Focus on Vancomycin-Resistant E. faecium and Ampicillin-Resistant E. faecalis

BackgroundThe primary pathogens in genera enterococcus are E. faecalis and E. faecium, increasing acquired resistance to glycopeptides and β lactamic has done the management more challenging. We aimed to describe the risk factors for acquisition of bacteremia for vancomycin-resistant E. faecium (VRE) and ampicillin-resistant E. faecalis (ARE) and the 30-day mortality in comparison to susceptible enterococcal bloodstream infection (BSI)MethodsFrom 2007- 2017 medical records of all BSI for E. faecalis and E. faecium were evaluated. Risk factor for acquisition of VRE and ARE as well as the significant variables associated with 30-day mortality for enterococcal BSI were determined by univariate and multivariate analysis. The molecular mechanism of VRE was performed by PCRResultsThere were 192 patients with E. faecium BSI of which 107(56%) patients had VRE BSI with 94% VRE strains expressing vanA gene. The index bacteremic episodes were classified as nosocomial o healthcare associated in 99%, 102(95%) had hospitalization 1 year before and 101(94%) history of use of antibiotics 3 months earlier, the multivariate analysis showed duration of the previous hospitalization >10 days (OR, 80.18; 95% CI, 1.81–634), use of central venous catheter [OR, 11.15; 95% CI, 2.48–50.2), and endotracheal cannula [OR, 17.91; 95% CI, 1.22–262) as significant associated variables. The mortality for VRE was greater than susceptible E. faecium (60% vs. 24%, P < 0.001). The only factors for 30-day mortality for E. faecium BSI in the multivariate analysis was APACHE ll score [OR,1.45; 95% CI, 1.26–1.66) and patients with chemotherapy of cancer. (OR, 3.52; 95% CI, 1.09–11.39). 147 patients had E. faecalis BSI of which 18 (11%) patients had ARE, we did not find relevant clinical differences of ARE in comparison with ampicillin-susceptible E. faecalis, neither in risk factors for acquisition of ARE nor 30-day mortality [7(39%) vs. 38(29%), P = 0.58] in uni and multivariate analysisConclusionOur evaluation showed in a period of 10 years that VRE expressing vanA gene had a strong association with patients with previous nosocomial exposure. Severely ill patients and cancer patients on chemotherapy during the bacteremic episode were the variables more associated with 30-day mortality. ARE is yet of low prevalence and less known, constant surveillance about it is warrantedDisclosures All authors: No reported disclosures.

Gene therapy for Cystic Fibrosis: Improved delivery techniques and conditioning with lysophosphatidylcholine enhance lentiviral gene transfer in mouse lung airways

ABSTRACT Purpose/Aim: Cystic fibrosis (CF) is the most common, fatal recessive genetic disease among the Caucasian population. Gene therapy has the potential to treat CF long term, however physiological barriers can prevent VSV-G pseudotyped lentiviral (LV) vectors from efficiently accessing the relevant receptors on the basolateral membrane of airway epithelial cells. The aims of this experiment were to use our new dose delivery techniques to determine whether conditioning the mouse lung conducting airways with lysophosphatidylcholine (LPC) improves the level of airway gene expression. Materials and Methods: Anaesthetised normal C57Bl/6 mice were intubated with an endotracheal cannula to non-invasively facilitate airway access. The airways were conditioned with 0.1% LPC, 0.3% LPC, or PBS (control) instilled via the ET tube. One hour later a VSV-G pseudotyped LV vector carrying the LacZ transgene was delivered. LacZ expression was measured by X-gal staining of the excised lungs 3 months after gene delivery. Results: Endotracheal intubation enabled precise dose delivery to the trachea and conducting airways. The cartilaginous airways of the groups conditioned with 0.1% and 0.3% LPC contained significantly larger numbers of LacZ positive cells compared to the PBS control group. In the LPC conditioned groups the majority of cell transduction was in ciliated epithelial cells. Conclusion: LPC conditioning prior to LV vector delivery, substantially enhanced the level of conducting airway gene expression after a single gene vector delivery. These results extend the previously established effectiveness of this protocol for producing gene expression in the nasal airways to the lung airways, the primary site of deleterious pathophysiology in CF individuals.

Nasopharyngeal Symptoms caused by Abnormal Inflation of the Endotracheal Tube in Patients undergoing Cervical Spine Surgery

Background:Abnormal balloon inflation of the endotracheal tube can cause nasopharyngeal symptoms. The objective is to describe Signs and Symptoms caused by the Abnormal Insufflated Balloon of the Endotracheal Cannula on patients undergoing Cervical Spine Surgery under General Anesthesia.Methods:Descriptive study, 39 patients underwent cervical spine surgery under general anesthesia, all of them were older than 18 years old and ASA I and II. The pressure balloon inflation of the endotracheal tube was measured by a manual manometer VBM Medizintechnik GmbH, measurements were made at the beginning of the procedure, and every hour during the transanesthetic period. The patients underwent a questionnaire about their symptoms on the recovery area and 24 hours after extubation.Results:39 patients, 59% men, 41% women. Average age was 47, minimum 15 – maximum 77, SD 14.26 years old. The average pressure balloon inflation at the moment of intubation was 30.7 mmHg and at the moment of extubation was 29.07 mmHg. The symptoms presented on the Recovery Care Unit and at 24 hours were: pain, inflammation, dysphagia, foreign body sensation.Conclusions:The pressure balloon inflation of the endotracheal cannula is important, because a pressure greater than 30mmHg produce symptoms. Changes on the patient’s position produced variations on the balloon pressure; therefore, continuous monitorization of the pressure baloon must be done.

Prone positioning of patients during venovenous extracorporeal membrane oxygenation is safe and feasible

Prone positioning of patients with acute respiratory distress syndrome (ARDS) has been shown to significantly improve survival rates. Prone positioning reduces collapse of dorsal lung segments with subsequent reduction of alveolar overdistension of ventral lung segments, optimizes lung recruitment and enhances drainage. Patients with ARDS treated by extracorporeal membrane oxygenation (ECMO) can also benefit from prone positioning; however, the procedure is associated with a possible higher risk of serious adverse events. The aim of this study was to evaluate the safety and feasibility of prone positioning for patients with severe ARDS during ECMO therapy. This study involved a retrospective analysis of all patients placed in a prone position while being treated by venovenous ECMO (vvECMO) for severe hypoxemia in ARDS as bridge to recovery in the interdisciplinary intensive care unit at the University Hospital Leipzig between January 2009 and August 2013. Baseline data, hospital mortality and serious adverse events were documented. Serious adverse events were defined as dislocation or obstruction of endotracheal tube or tracheal cannula, ECMO cannulas and cardiac arrest. Prone positioning was carried out by at least one doctor and three nurses according to a standardized protocol. Results are given as the median (1st and 3rd quartiles). A total of 26 patients were treated with vvECMO as bridge to recovery due to severe ARDS. Causes for ARDS were pneumonia (n = 20) and aspiration (n = 2) and four patients had different rare causes of ARDS. The median time on ECMO was 8 days (6;11) and during this period 134 turning events were documented. Patients were proned for a median of 5 (3;7) periods with a median duration of 12 h (8;12). No serious adverse events were recorded. The hospital mortality was 42% and mortality during the ECMO procedure was 35%. Prone positioning significantly reduces the mortality of patients with severe ARDS. In this series of 26 patients with severe ARDS during ECMO therapy no serious adverse events were found during the use of prone positioning.

Weaning from tracheostomy in subjects undergoing pulmonary rehabilitation.

BackgroundWeaning from tracheostomy has implications in management, quality of life, and costs of ventilated patients. Furthermore, endotracheal cannula removing needs further studies. Aim of this study was the validation of a protocol for weaning from tracheostomy and evaluation of predictor factors of decannulation.MethodsMedical records of 48 patients were retrospectively evaluated. Patients were decannulated in agreement with a decannulation protocol based on the evaluation of clinical stability, expiratory muscle strength, presence of tracheal stenosis/granulomas, deglutition function, partial pressure of CO2, and PaO2/FiO2 ratio. These variables, together with underlying disease, blood gas analysis parameters, time elapsed with cannula, comordibity, Barthel index, and the condition of ventilation, were evaluated in a logistic model as predictors of decannulation.Results63 % of patients were successfully decannulated in agreement with our protocol and no one needed to be re-cannulated. Three variables were significantly associated with the decannulation: no pulmonary underlying diseases (OR = 7.12; 95 % CI 1.2–42.2), no mechanical ventilation (OR = 9.55; 95 % CI 2.1–44.2) and period of tracheostomy ≤10 weeks (OR = 6.5; 95 % CI 1.6–27.5).ConclusionsThe positive course of decannulated patients supports the suitability of the weaning protocol we propose here. The strong predictive role of three clinical variables gives premise for new studies testing simpler decannulation protocols.

Preterm piglet model for investigation of preterm human neonatal co‐morbidities

Piglets have anatomy and physiology similar to humans, but published reports state that piglets less than 90% gestation are non‐viable even with intensive care. The objective was to provide proof of principle that a piglet in the Piglet Neonatal Intensive Care Unit (PNICU) less than 90% gestation can be viable and exhibit co‐morbidities frequently observed in preterm neonates in the Neonatal Intensive Care Unit (NICU). A piglet was delivered by caesarian section at 87% gestation, admitted to the PNICU, surgically implanted with an endotracheal cannula and a double lumen jugular vein catheter, and provided 24 hour NICU level of care including ventilation and parenteral nutrition. The piglet received periodic hyperoxia treatments during the course of PNICU care. On day 9 tissues and bodily fluids were collected. The piglet became ventilator dependent and had several episodes of oxygen desaturation and elevated heart rate accompanied by unusual rhythmical movements of the head, eyes and legs. Gross morphology of lungs was consistent with pulmonary damage associated with prematurity. Visual examination revealed some areas of the jejunum had luminal blood present. The retina was classified as immature by retinal exam performed by an ophthalmologist using NICU methods. A piglet less than 90% gestation can be used to investigate the co‐morbidities of preterm human neonates.Supported by Mead Johnson Nutrition Company

Influence of Polysaccharides from Aloe vera (Aloe barbadensis Miller, Liliaceae) on Mechanically Induced Cough in Cats

Different plants have been reported to be a source of polysaccharides that possess a great variety of biological activities, including cough suppression. The experiments were aimed on the influence of two polysaccharides isolated from the gel (A, HF1-Z) and one from the epidermis (SL-1) of Aloe vera leaves, characterized by chemical composition and structural properties, on the cough reflex. The method of mechanically induced cough was used in conscious cats. A nylon fibre directed individually into the mucous area of the laryngopharyngeal and tracheobronchial airways via endotracheal cannula elicited the cough reflex. Statistical evaluation registered cough reflex indicators (number of cough efforts - NE, cough frequency - NE min–1 intensity of cough attacks during expiration and inspiration - IA+ and IA-, intensity of maximal inspiratory and expiratory cough efforts - IME- and IME+) showed that gel polysaccharide HF1-Z possessed higher cough-suppressing activity than dropropizine, a nonnarcotic peripheral cough suppressant. Their antitussive activity was accompanied mainly with a decrease of NE, IA+ and IA- from both laryngopharyngeal and tracheobronchial mucous areas of the airways. Results of the presented study also showed minimal influence of polysaccharide HF1-Z on expectoration predictor, IME- and IME+. New pharmacodynamic property of polysaccharides isolated from Aloe vera was shown during experiments, which could be a base of their possible therapeutic use in this indication in future.

Letaler Verlauf einer pseudomembranösen Enterokolitis unter parenteraler Gabe von Vancomycin und Imipenem

A 48-year-old woman required mechanical ventilation after aortic valve replacement for decompensated aortic valve stenosis when bleeding complications developed and rethoracotomy had to be performed. Acute renal failure necessitated haemodialysis. Septic fever of unknown aetiology failed to respond to oxacillin, cefotaxim and tobramycin. The endotracheal cannula and central venous catheter were changed on the 24th postoperative day and the antibiotic treatment altered to 250 mg imipenem and 125 mg vancomycin three times daily intravenously. The fever soon subsided, but recurred on the 32nd postoperative day, accompanied by increasing leucocytosis. The patient was obstipated but had no intraabdominal signs. Four days later ultrasonography demonstrated thickening of the intestinal wall and coloscopy showed typical pseudomembranous colitis. Intestinal contents were positive for Clostridium difficile toxin. Despite immediate rectal and intragastric administration of 250 mg vancomycin four times daily the patient died of pseudomembranous colitis, confirmed at autopsy. The case demonstrates that vancomycin cannot always prevent the development of pseudomembranous colitis.

Bronchioalveolar lavage with perfluorochemical liquid during conventional ventilation

Therapeutic approaches with bronchioalveolar lavage are currently used in infants with severe alveolar space-occupying material. In many circumstances, bronchioalveolar lavage has been performed in conjunction with extracorporeal membrane oxygenation. A 2-month-old boy with severe respiratory failure requiring assisted ventilation did not respond to any conventional treatments, including surfactant. An open-lung biopsy showed intra-alveolar accumulation of proteinaceous material and foamy macrophages but was not diagnostically conclusive. Therapeutic trials with bronchioalveolar lavage using normal saline were unsuccessful, causing episodes of severe hypoxemia. Then, bronchioalveolar lavage during conventional mechanical ventilation was performed with the use of a medical-grade perfluorochemical liquid (perfluordecalin). After instillation of liquid (10 mL/kg), the lungs were refilled three times during the first 24 hrs and repeated 48 hrs later. During perfluorochemical liquid treatment, the infant's condition remained stable, with small improvements in pulmonary mechanics. Suction from the endotracheal cannula yielded only small amounts of gelatinous material. Considering the progression of the disease and just minimal pulmonary improvements by this intervention, further treatment was considered futile. Support was, thus, minimized, and the infant died a few days later. An autopsy revealed the diagnosis to be consistent with Niemann-Pick C2 disease. This study demonstrated that bronchioalveolar lavage with perfluorochemical liquid could be performed safely during conventional mechanical ventilation without the additional support of extracorporeal membrane oxygenation in infants with severe alveolar space-occupying material.

On the fetal origin of asthma: Effect of maternal allergen exposure on the airway responses of the guinea pig offspring later in life

ON THE AIRWAY RESPONSES OF THE GUINEA PIG OFFSPRING LATER IN LIFE EGLE BYTAUTIENE, YURI VEDERNIKOV, WILLIAM MANER, MONICA LONGO, GARY DV HANKINS, GARLAND D. ANDERSON, GEORGE SAADE, University of Texas Medical Branch, Obstetrics & Gynecology/Maternal Fetal Medicine, Galveston, Texas OBJECTIVE: Epidemiological and experimental studies support a fetal origin for cardiovascular adult diseases. The familial and epidemiological characteristics of asthma may also be explained by a fetal origin. Our objective was to determine the effect of maternal exposure to allergens on the airway responses of offspring later in life using a well-characterized animal model for asthma research. STUDY DESIGN: 3 months old guinea pig offspring born to ovalbuminsensitized and nonsensitized mothers were tested for sensitivity to ovalbumin by intracutaneous injections. They were then anesthetized and ventilated via an endotracheal cannula connected to an ultrasonic nebulizer for antigen delivery, and to a transducer for measurement of pressure at the airway opening (PAO). After obtaining basal PAO, ovalbumin was nebulized for 1 min. After stabilization, ovalbumin was nebulized again after pretreatment with ketotifen (histamine H1 receptor antagonist). PAO was expressed as a percent change from basal PAO. Bronchoalveolar fluid (BALF) was collected 3 hours after first exposure to ovalbumin and eosinophil count was obtained. Student t test was used for analysis (significance: p!0.05). RESULTS: Skin thickening and erythema at the site of ovalbumin injection developed in all the offspring born to sensitized mothers, indicating an acute hypersensitivity reaction to antigen, but in none of the offspring of nonsensitized mothers. Exposure to aerosolized ovalbumin significantly increased PAO in the offspring born to sensitized mothers, indicating bronchoconstriction, and this response was completely abolished by ketotifen. Ovalbumin and ketotifen had no effect in pups of nonsensitized mothers. The number of eosinophils was significantly increased in BALF from offspring born to sensitized mothers compared with offspring born to non-sensitized mothers. CONCLUSION: Maternal exposure to allergen programs the fetus for hypersensitivity reaction to the same allergen later in life. Adult conditions related to environmental exposure to allergens, such as asthma, may have a fetal origin. SMFM Abstracts S175

Tracheotomy in growing rats: histological aspects

PURPOSE: To compare morphologically three different types of tracheotomy in growing rats, applying microsurgical technique. METHODS: EPM-1 Wistar growing rats (n=57) weighing 88gm and aged 35 days were randomized in four groups, according tracheotomy incision type (longitudinal, transverse and tracheal segment excision), and sham group. Following intramuscular anesthesia with ketamine and xylazine, the trachea was exposed and incised, according to the group, and a hand-made endotracheal cannula was inserted into the organ, under sterile conditions. This cannula was removed after 7 days, and animals have been sacrificed 30 days later. Tracheas samples were submitted to histological study, stained by hematoxylin-eosin and Masson trichrome, evaluating fibrosis, inflammatory infiltrate and epidermoid metaplasia. RESULTS: There was more frequency of inflammatory infiltrate at the tracheal epithelium in the tracheal segment excision group (87%) compared to the longitudinal (40%) and transverse (36%) incision groups (p=0.009). Evaluating epidermoid metaplasia, tracheal segment excision and the longitudinal groups presented 33% and 40%, respectively, compared to 0% of the transverse group (p=0.03). Concerning to fibrosis, in a global comparison (p=0.1) among the three groups there was no difference, however, compared to the longitudinal group the transverse group showed lower level of fibrosis (p=0.04). Sham group did not present any relevant morphologic alterations and it was used as reference pattern. CONCLUSION: Taken together, our data show that tracheal segment excision promotes more epithelium aggression and transverse tracheal incision shows less morphologic alterations.

SENSORY NERVE-MEDIATED NASAL VASODILATORY RESPONSE TO INSPIRED ETHYL ACRYLATE

The irritants acrolein, acetaldehyde, and acetic acid induce a rapid sensory nerve-mediated nasal vasodilatory response in the rat. The aim of the current study was to examine acute nasal sensory nerve-mediated acute responses to an irritant ester vapor, ethyl acrylate. For this purpose, the upper respiratory tract of the urethane-anesthetized male F344 rat was isolated by insertion of an endotracheal cannula, and ethyl acrylate-laden air was drawn continuously through that site at a flow rate of 100 ml/min for 50 min. Vascular function was monitored by measuring inert vapor (acetone) uptake throughout the exposure. Nasal flow resistance was also monitored during exposure, and plasma protein extravasation was measured by Evans blue dye leakage. At exposure concentrations of 100 to 400 ppm, ethyl acrylate induced a rapid nasal vasodilatory response, as indicated by increased acetone uptake rates. This response was maintained throughout the exposure. Changes in nasal flow resistance or in Evans blue dye leakage were not observed at these exposure concentrations. The vasodilatory response was diminished in animals pretreated with the sensory nerve toxin capsaicin, providing strong evidence that this response was sensory nerve mediated. Pretreatment with the carboxylesterase inhibitor bis- para -nitro-phenolphospahte at a dose sufficient to inhibit nasal carboxylesterase did not alter the response, suggesting that the parent ester, not the carboxylesterase metabolites, is primarily responsible for the sensory-nerve-mediated vasodilatory responses to this ester.

SENSORY-NERVE-MEDIATED NASAL VASODILATORY RESPONSE TO INSPIRED ACETALDEHYDE AND ACETIC ACID VAPORS

This study was designed to characterize the acute nasal vasodilatory responses to the sensory irritants acetaldehyde and acetic acid. For this purpose, the upper respiratory tract of the urethane-anesthetized male F344 rat was isolated by insertion of an endotracheal cannula, and irritant-laden air was drawn continuously through that site at a flow rate of 100 ml/min for 50 min. Vascular function was monitored by measuring inert vapor (acetone) uptake throughout the exposure. Both acetaldehyde and acetic acid induced an immediate concentration-dependent vasodilation as indicated by increased steady-state acetone uptake rates. This response was observed at exposure concentrations of 25 ppm or 130 ppm or higher for acetaldehyde or acetic acid, respectively. The response to either vapor was significantly diminished in rats pretreated with the sensory nerve toxin capsaicin (50 mg/kg, 7 days prior to exposure), providing evidence that sensory nerves play a role in the response. Acetaldehyde is metabolized by aldehyde dehydrogenase to acetic acid. Pretreatment with the aldehyde dehydrogenase inhibitor cyanamide (10 mg/kg, 1 h prior to exposure) reduced the vasodilatory response to 200 ppm but not to 50 ppm acetaldehyde. These results suggest that formation of acetic acid is important in the sensory nerve-mediated vasodilatory response to high, but perhaps not to low, concentrations of acetaldehyde.