Reducing Pediatric Tracheostomy Wound Complications: An Evidence-Based Literature Review.

OBJECTIVE: To discuss prevention strategies that can mitigate the frequency of tracheostomy-related wound complications. DATA SOURCES: A systematic literature review of PubMed between 2010 and 2019. STUDY SELECTION: Full-text articles written in English language and studying human participants younger than 18 years. DATA EXTRACTION: The primary outcome was the rate of tracheostomy-related skin complications after implementation of a given intervention. Secondary outcomes included rates of accidental decannulation or other complications. DATA SYNTHESIS: A total of 348 studies were identified and 6 met inclusion criteria. There were 1,607 children included with interventions designed to reduce peristomal and cervical wound complications in 1,174 (73.1%). Strategies considered safe and effective included protective skin barriers, reducing prolonged pressure, and early wound identification protocols. CONCLUSIONS: Wound complications after pediatric tracheostomy can be reduced using a multifaceted approach by providers committed to making skin care a priority.

Surgical closure of the larynx for intractable aspiration pneumonia: cannula-free care and minimizing the risk of developing trachea-innominate artery fistula.

There is a risk of developing a fatal trachea-innominate artery fistula following laryngotracheal separation for the prevention of intractable aspiration pneumonia. We developed a novel technique of surgical closure of the larynx to avoid this complication and provide long-term cannula-free care.

Incentive spirometry for prevention of postoperative pulmonary complications in upper abdominal surgery.

BACKGROUND: This is an update of a Cochrane Review first published in The Cochrane Library 2008, Issue 3.Upper abdominal surgical procedures are associated with a high risk of postoperative pulmonary complications. The risk and severity of postoperative pulmonary complications can be reduced by the judicious use of therapeutic manoeuvres that increase lung volume. Our objective was to assess the effect of incentive spirometry compared to no therapy or physiotherapy, including coughing and deep breathing, on all-cause postoperative pulmonary complications and mortality in adult patients admitted to hospital for upper abdominal surgery. OBJECTIVES: Our primary objective was to assess the effect of incentive spirometry (IS), compared to no such therapy or other therapy, on postoperative pulmonary complications and mortality in adults undergoing upper abdominal surgery.Our secondary objectives were to evaluate the effects of IS, compared to no therapy or other therapy, on other postoperative complications, adverse events, and spirometric parameters. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 8), MEDLINE, EMBASE, and LILACS (from inception to August 2013). There were no language restrictions. The date of the most recent search was 12 August 2013. The original search was performed in June 2006. SELECTION CRITERIA: We included randomized controlled trials (RCTs) of IS in adult patients admitted for any type of upper abdominal surgery, including patients undergoing laparoscopic procedures. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality and extracted data. MAIN RESULTS: We included 12 studies with a total of 1834 participants in this updated review. The methodological quality of the included studies was difficult to assess as it was poorly reported, so the predominant classification of bias was 'unclear'; the studies did not report on compliance with the prescribed therapy. We were able to include data from only 1160 patients in the meta-analysis. Four trials (152 patients) compared the effects of IS with no respiratory treatment. We found no statistically significant difference between the participants receiving IS and those who had no respiratory treatment for clinical complications (relative risk (RR) 0.59, 95% confidence interval (CI) 0.30 to 1.18). Two trials (194 patients) IS compared incentive spirometry with deep breathing exercises (DBE). We found no statistically significant differences between the participants receiving IS and those receiving DBE in the meta-analysis for respiratory failure (RR 0.67, 95% CI 0.04 to 10.50). Two trials (946 patients) compared IS with other chest physiotherapy. We found no statistically significant differences between the participants receiving IS compared to those receiving physiotherapy in the risk of developing a pulmonary condition or the type of complication. There was no evidence that IS is effective in the prevention of pulmonary complications. AUTHORS' CONCLUSIONS: There is low quality evidence regarding the lack of effectiveness of incentive spirometry for prevention of postoperative pulmonary complications in patients after upper abdominal surgery. This review underlines the urgent need to conduct well-designed trials in this field. There is a case for large RCTs with high methodological rigour in order to define any benefit from the use of incentive spirometry regarding mortality.

Resection of the innominate artery to prevent an impending tracheoinnominate fistula and to permit tracheotomy in a patient with subglottic stenosis and high-riding innominate.

OBJECTIVE: This study aimed to determine the long-term viability of innominate artery resection and tracheotomy for a patient at high risk of developing a tracheoinnominate fistula (TIF) in the setting of subglottic stenosis and a high-riding innominate artery. METHODS: Chart review with 2-year follow-up. RESULTS: A 45-year-old diabetic man with obstructive sleep apnea and multiple admissions for coma and delirium tremens associated with alcohol abuse developed subglottic stenosis. He was found to have a palpable supraclavicular pulse during preoperative examination for a tracheotomy. Computed tomography examination revealed a high-riding innominate artery at the level of stenosis along with granulation tissue and disruption of the cartilaginous trachea, suggesting a high risk of impending TIF. The patient underwent a sternotomy-approach resection of the innominate artery with closure of the distal stump with a sternohyoid muscle flap. Intraoperatively, a plane of adhesions between the posterior innominate artery and trachea was dissected. The anterior tracheal wall appeared calcified but without evidence of erosion of either the trachea or the artery. Six weeks later, a tracheotomy was performed. Follow-up at 27 months did not identify complications from the innominate artery resection. CONCLUSION: Resection of the innominate artery is an option for some patients either to address the warning signs of TIF or to permit a tracheotomy to be performed in the presence of a high innominate artery.

[Endoscopic diagnosis, treatment and prevention of intubation related injuries of the larynx and trachea in neurosurgical patients].

The goal of the study was to assess of efficacy of endoscopic diagnosis, prevention and treatment of intubation related larynx and tracheal injuries in patients with acute neurosurgical pathology and prolonged mechanical ventilation. 199 patients with different neurosurgical pathology were enrolled in the study group. Mean age was 50 +/- 14. Control group consisted of 399 patient. Mean age was 43 +/- 12. Clinical state of patient from both group were similar. Endoscopic method in the study group included revision of airways via nasal route with tracheostomy tube inserted. Larynx and tracheal injuries by endoscopy were identified in 42 patients (33.6%) in the study group and in 12 patients (7.6) in the control group. Such injuries weren't mentioned in 83 patients in study group and in 146 patients of the control group. Tracheal stenosis was developed in the study group in 0,8% of patients, which is by 7,9 times lower than in the control group (6.3%). We consider that this result was achieved due to our approach to treatment and prevention of tracheal stenosis.

Reducing fistula rates following laryngotracheal separation.

OBJECTIVES: Laryngotracheal separation (LTS) is an uncommonly performed but highly effective procedure for intractable aspiration in patients with amyotrophic lateral sclerosis and other neurodegenerative conditions. Previously published series have noted rates of postoperative tracheocutaneous fistula formation as high as 1 in 3 patients. This report details the use of a muscle flap-reinforced imbrication technique to reduce the incidence of fistula formation after LTS surgery. METHODS: All patients who underwent LTS surgery at the reporting institutions between 2004 and 2010 were identified. The principal diagnosis, patient characteristics, the presence of a preexisting tracheotomy, and postoperative complications were recorded. We describe the technique for imbrication closure of the proximal stump with strap muscle reinforcement. RESULTS: Thirteen patients (10 male, 3 female; median age, 53 years; interquartile range, 45 to 66 years) underwent the LTS procedure; amyotrophic lateral sclerosis was the principal diagnosis in 8 of the 13 patients. Six patients had a preexisting tracheotomy. None developed tracheocutaneous fistula, hematoma, or wound infection. Two patients required stomaplasty at a later date. CONCLUSIONS: Strap muscle flap-reinforced imbrication closure of the proximal tracheal stump after LTS surgery allows for a low incidence of postoperative fistula formation.

[Survival analysis for patients with severe motor and intellectual disabilities following tracheotomy].

To investigate the survival rate and causes of death in patients with severe motor and intellectual disabilities (SMIDs) that necessitated tracheotomy, we retrospectively analyzed 90 patients who underwent tracheotomy between 1990 and 2009. Indications for tracheotomy in these patients were upper airway obstruction (44 patients), recurrent aspiration pneumonia (28 patients), retained secretions (23 patients), prolonged mechanical ventilation (18 patients), chronic respiratory failure (9 patients), central respiratory failure (5 patients), and gastroesophageal reflux (8 patients). Most of the patients underwent tracheotomy at the age of 0-5 years or 10-19 years. As of April 1, 2010, 28 patients had died. The survival rate was 0.91 at 1 year, 0.74 at 5 years, 0.59 at 10 years, 0.54 at 15 years, and 0.40 at 19 years after tracheotomy. Massive tracheal bleeding due to development of tracheo-innominate artery fistulas occurred in 5 patients, and 4 of them died. They were thirteen years of age or older when they underwent tracheotomy, and developed fistulas after 2 weeks or later. In contrast, 7 patients at high risk for fistula formation, including those that had developed severe tracheomalacia associated with granulation or warning hemorrhages, underwent preventive resection of the innominate artery, and all of them had survived. It is important to regularly evaluate patients with SMIDs who have undergone tracheotomy by using bronchofiberscopy to identify risk factors for tracheoinnominate artery fistulas, a preventable cause of death.

[Experience of 3 successfully treated cases of tracheo-innominate artery fistula and significance of preventive surgery].

Tracheo-innominate artery fistula (TIF) is a rare but fatal complication after tracheostomy. Necessary lifesaving measures include proper ventilation, temporary hemostasis, and surgery. Recently, we successfully managed 3 cases of TIF. Ventilation and temporary hemostasis were secured by a long endotracheal tube and overinflated cuff. Division of the innominate artery, restoration of the tracheal fistula with an autologous pericardial patch or direct closure, and aorto-innominate bypass grafting or extra-anatomical bypass grafting with a polytetrafluoroethylene (PTFE) graft were performed through an emergency median sternotomy. All 3 patients recovered with no problems. After TIF occurs, the patient's condition rapidly worsens, and the risk of bacterial contamination in the operative field may increase. Surgical intervention should be performed for patients with tracheal stenosis who are judged to be at high risk for TIF. This preventive surgery includes bypass grafting to divide the innominate artery and partial resection of the anterior bony thorax(upper sternum, medial part of clavicles, and anterior part of upper ribs if necessary). We believe that this procedure will improve tracheal stenosis and minimize the risk of TIF. Thus far, 10 patients have undergone this operation, and their mid-term results are satisfactory.

Endotracheal tube cuff pressures in pediatric patients intubated before aeromedical transport.

OBJECTIVES: Prolonged endotracheal tube cuff pressures (ETTCPs) greater than 30 cm H2O can cause complications. With increasing utilization of cuffed endotracheal tubes (ETTs) in pediatric patients comes the risk of overinflation. We evaluated the incidence of elevated ETTCP in pediatric patients intubated with cuffed ETTs, transported by a critical-care transport service and attempted to identify whether elevated ETTCP was associated with factors such as patient demographics, diagnostic category, and intubator credentials. METHODS: In this prospective study, assessment of ETTCP was made upon transport crew arrival at the bedside. The study focused on a consecutive sample of pediatric patients undergoing transport with cuffed ETTs placed before transport team arrival. All patients had cuff pressures assessed by the same cuff manometry device. Pressures found to be greater than 30 cm H2O were corrected immediately. RESULTS: Forty-one percent of cases met the a priori defined cutoff for elevated ETTCP of 30 cm H2O; 30% of those elevated cuff pressures were twice that cutoff (>60 cm H2O). There were no associations between high ETTCP and any of the following independent variables: demographics, physician versus nonphysician intubator, and intubation location (ie, scene vs emergency department vs intensive care unit). CONCLUSIONS: A significant number of pediatric patients transported by a critical-care transport service had elevated ETTCP. Furthermore, there was no clear risk factor for elevated cuff pressures. This is further evidence that cuff pressures should be measured in all patients. Further research should focus on the effect of educational intervention and on the possible clinical results of elevated ETTCPs.

Anesthesia management for emergency laparotomy in a pediatric patient with suspected hereditary angioedema.

Hereditary angioedema (HAE) is caused by complement factor 1 inhibitor (C1-INH) deficiency, and its mode of inheritance is autosomal dominant. We present a case of an 8-year-old patient who required emergency laparotomy after a traffic accident. General anesthesia with tracheal intubation was necessary. The patient's mother and maternal grandmother had been diagnosed with HAE. HAE is associated with high mortality when airway edema is caused by tracheal intubation. It was impossible to rule out HAE preoperatively in the patient. Therefore, we presumed that he had HAE and treated him with pasteurized C1-INH concentrate. The patient underwent laparotomy uneventfully. Several days after the operation, the laboratory data revealed that the perioperative plasma complement 1 q subunit (C1q) protein level and C1-INH function were not lowered. The diagnosis of HAE was not confirmed, but it was not possible to rule out the diagnosis either. The prophylactic use of a C1-INH in this case may be justified, because the procedure was an emergency and because of the high mortality associated with tracheal intubation in patients with HAE.

Accuracy of the minimal leak test for endotracheal cuff pressure monitoring.

OBJECTIVES: To determine the accuracy of the minimum leak test as a surrogate for target endotracheal cuff pressure of 20-30 cm H2 O in intubated patients. METHODS: Cuff pressures were measured at the University of Miami Hospital using the minimum leak test on every intubated patient once per shift, then cuff pressure was reevaluated using handheld numerical manometers and recorded pressures above or below the target range, readjusting the pressure as needed. This assessment was repeated throughout each patient's intubation for up to 6 days. The readjustment rate of the test and the probability of a patient needing at least one adjustment were determined. RESULTS: One hundred twenty-two patients were evaluated. Median age was 67 years (range 29-95), 52% were male, 48% were female. Patients were followed for an average of 4.7 days. Seven hundred twenty-two minimum leak tests were performed. Of these, 170 required readjustment into the target range (24% readjustment rate). Of the tests outside target range, 66% of cuffs were overinflated and 34% were underinflated. Fifty-five percent of patients required at least one adjustment. CONCLUSION: Despite ubiquitous use of the minimum leak test for endotracheal cuff pressure adjustment, the test has an unacceptably high error rate resulting in cuff pressures above or below the target range. Most patients will require at least one adjustment throughout an intubation, putting them at risk for tracheal injury, stenosis, or leak and aspiration. The minimum leak test is not sufficiently accurate for endotracheal cuff pressure monitoring. Formal manometry is superior and should be used to optimize patient outcomes. LEVEL OF EVIDENCE: 4 Laryngoscope, 130:1646-1650, 2020.

Clinical review: post-extubation laryngeal edema and extubation failure in critically ill adult patients.

Laryngeal edema is a frequent complication of intubation. It often presents shortly after extubation as post-extubation stridor and results from damage to the mucosa of the larynx. Mucosal damage is caused by pressure and ischemia resulting in an inflammatory response. Laryngeal edema may compromise the airway necessitating reintubation. Several studies show that a positive cuff leak test combined with the presence of risk factors can identify patients with increased risk for laryngeal edema. Meta-analyses show that pre-emptive administration of a multiple-dose regimen of glucocorticosteroids can reduce the incidence of laryngeal edema and subsequent reintubation. If post-extubation edema occurs this may necessitate medical intervention. Parenteral administration of corticosteroids, epinephrine nebulization and inhalation of a helium/oxygen mixture are potentially effective, although this has not been confirmed by randomized controlled trials. The use of non-invasive positive pressure ventilation is not indicated since this will delay reintubation. Reintubation should be considered early after onset of laryngeal edema to adequately secure an airway. Reintubation leads to increased cost, morbidity and mortality.

Incentive spirometry for prevention of postoperative pulmonary complications in upper abdominal surgery.

BACKGROUND: Upper abdominal surgical procedures are associated with a high risk of postoperative pulmonary complications. The risk and severity of postoperative pulmonary complications can be reduced by the judicious use of therapeutic manoeuvres that increase lung volume. Our objective was to assess the effect of incentive spirometry (IS) compared to no therapy, or physiotherapy including coughing and deep breathing, on all-cause postoperative pulmonary complications and mortality in adult patients admitted for upper abdominal surgery. OBJECTIVES: To assess the effects of incentive spirometry compared to no such therapy (or other therapy) on all-cause postoperative pulmonary complications (atelectasis, acute respiratory inadequacy) and mortality in adult patients admitted for upper abdominal surgery. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2006, Issue 3), MEDLINE, EMBASE, and LILACS (from inception to July 2006). There were no language restrictions. SELECTION CRITERIA: We included randomized controlled trials of incentive spirometry in adult patients admitted for any type of upper abdominal surgery, including patients undergoing laparoscopic procedures. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality and extracted data. MAIN RESULTS: We included 11 studies with a total of 1754 participants. Many trials were of only moderate methodological quality and did not report on compliance with the prescribed therapy. Data from only 1160 patients could be included in the meta-analysis. Three trials (120 patients) compared the effects of incentive spirometry with no respiratory treatment. Two trials (194 patients) compared incentive spirometry with deep breathing exercises. Two trials (946 patients) compared incentive spirometry with other chest physiotherapy. All showed no evidence of a statistically significant effect of incentive spirometry. There was no evidence that incentive spirometry is effective in the prevention of pulmonary complications. AUTHORS' CONCLUSIONS: We found no evidence regarding the effectiveness of the use of incentive spirometry for prevention of postoperative pulmonary complications in upper abdominal surgery. This review underlines the urgent need to conduct well-designed trials in this field. There is a case for large randomized trials of high methodological rigour in order to define any benefit from the use of incentive spirometry regarding mortality.

A Computed Tomographic Assessment of Tracheostomy Tube Placement in Patients with Chronic Neurological Disorders: The Prevention of Tracheoarterial Fistula.

Objective Tracheoarterial fistula (TAF) is a rare but devastating complication of tracheostomy caused by pressure necrosis from the elbow, tip, or over-inflated cuff of the tracheostomy tube. The incidence of TAF is reportedly higher in patients with neurological disorders than in those without such disorders. To evaluate the incidence of and factors contributing to the misalignment of tracheostomy tubes in bedridden patients with chronic neurological disorders. Methods We retrospectively assessed three-dimensionally reconstructed serial computed tomography (CT) images to see if the tip of the tube made contact with the tracheal wall and if the main arteries were running adjacent to the tube's elbow, tip or cuff. Results The tip of the tube was in contact with the tracheal wall in 14 of the 30 patients assessed. Among them, the tip was adjacent to the innominate artery in eight, the aortic arch in three and an aberrant right subclavian artery in one. In one patient with the tube tip adjacent to the aortic arch and the other four patients, the cuff of the tube was adjacent to the innominate artery across the tracheal wall. Patients with the tube tip in contact with the anterior tracheal wall had a significantly greater cervical lordosis angle than those without contact (p<0.05). Conclusion More than half of tracheostomized patients with chronic neurological disorders had a latent risk of TAF. The variability in the location of the innominate artery, anomalies of the aortic arch, and skeletal deformities may therefore be contributing factors.

[Delineation of the anatomical relationship of innominate artery and trachea by respiratory-gated MR imaging with true FISP sequence in patients with severe motor and intellectual disabilities].

Tracheoinnominate artery fistula is a well-known complication that arises on using a cannula. Therefore, routine examination of the anatomical relationship of the innominate artery and trachea should be carried out. We evaluated the usefulness of magnetic resonance imaging in 5 patients with severe motor and intellectual disabilities (SMID) using a combination of true-fast imaging of steady-state precession (true-FISP) sequences and two-dimensional prospective acquisition correction (2D-PACE). For all patients, the trachea and the innominate artery were identified without sedation and contrast media. In one patient, the innominate artery was observed to be pressing on the trachea. In three patients, the trachea and innominate artery were brought very close each other, and in the other patient the anatomical relationship of the trachea and surrounding structure was delineated before tracheotomy. The validity of true-FISP sequences combined with the respiratory-gated technique was confirmed useful for the patients who are difficult to lie quietly and to hold their breath voluntarily.

Recognition and Management of Life-Threatening Tracheovascular Fistulae and How to Prevent Them.

Formation of a fistula between trachea and a major artery or vein in the root of the neck threatens life quickly from combination of major external bleeding and hemorrhagic shock, and asphyxiation from flooding of the proximal airways with blood. This complication can occur after cervical tracheostomy open or percutaneous, tracheal resection, cervical exentration and anterior mediastinal tracheostomy, and laryngectomy. The recognition of its occurrence is clinical based on a high index of clinical suspicion. The life-saving operation for this complication carries potential risk for ischemic stroke. Impairment of arterial perfusion to the right arm and ischemia is another potential complication.

Tracheal Injuries Complicating Prolonged Intubation and Tracheostomy.

Respiratory care advances such as the introduction of ventilatory assistance have been associated with postintubation airway stenosis resulting from tracheal injury at the site of the inflatable cuff on endotracheal or tracheostomy tubes. Low-pressure cuffs have significantly reduced this occurrence. Loss of airway stability at the site of a tracheostomy stoma may result in tracheal stenosis. Subglottic stenosis may result from a high tracheostomy site at, or just inferior to, the cricoid arch, or to malposition of an endotracheal tube cuff. Awareness of these complications and their causes is essential to prevent their occurrence.

Single-dose versus two-dose dexamethasone effects on lung inflammation and airway reactivity in meconium-instilled rabbits.

Two doses of the corticosteroid dexamethasone may alleviate meconium-induced acute lung injury more effectively than a single dose. Meconium-instilled rabbits intravenously received dexamethasone (0.5 mg/kg) at one dose 0.5 hours after meconium instillation or at two doses 0.5 hours and 2.5 hours after meconium instillation or were left without treatment, and were oxygen-ventilated for additional 5 hours. At the end of experiment, lungs and trachea were excised. Two doses of dexamethasone effectively diminished meconium-induced lung edema, tracheal hyperreactivity to histamine, neutrophil count in bronchoalveolar lavage fluid, and decreased oxidative modifications of proteins and lipids in lung homogenate compared with the non-treated group. Single-dose dexamethasone also reduced lung edema, lung neutrophils, and tracheal hyperreactivity to histamine, but these effects were weaker than those after two-dose dexamethasone. We conclude that two-dose dexamethasone is superior to single-dose dexamethasone in prevention lung injury in meconium-instilled rabbits.

Interferon-gamma knockout fails to confer protection against obliteration in heterotopic murine tracheal allografts.

BACKGROUND: Interferon-gamma, produced by T-helper cells, activates macrophages and increases expression of major histocompatibility complex (MHC) products in acute and chronic rejection. We investigated the role of interferon-gamma in murine heterotopic tracheal allografts. METHODS: Tracheas from BALB/c mice were heterotopically transplanted to BALB/c (12 isografts: 2 weeks [n = 6] and 4 weeks [n = 6], C57BL/6 (12 allografts: 2 weeks [n = 6] and 4 weeks [n = 6]) and C57BL/6 interferon-gamma knockout mice (12 interferon-gamma knockout allografts: 2 weeks [n = 4] and 4 weeks [n = 8]). BALB/c interferon-gamma knockout tracheas were transplanted to C57BL/6 mice (reverse knockout: 4 weeks [n = 6]) and BALB/c interferon-gamma knockout mice (4 weeks [n = 2]). C57BL/6 tracheas were transplanted to Bm12 mice (MHC Class II mismatch allografts: 4 weeks [n = 6]). Conventional histology and immunohistochemistry for CD4, CD8 and CD11b were performed. RESULTS: Minimal (<20%) obliteration was seen at 2 weeks in the allograft groups. No obliteration was seen in the isograft groups. However, all allografts were completely obliterated at 4 weeks. Interferon-gamma knockout allograft combinations displayed severe rejection characterized by intense intra- and extraluminal infiltration by CD4-, CD8- and CD11b-labeled cells. The MHC Class II mismatch allograft group showed normal epithelium and mild sub-epithelial infiltration by CD4+ cells at 4 weeks (CD8-, CD11b-). CONCLUSIONS: Absence of interferon-gamma does not protect the allograft from obliteration. Epithelial destruction by cytotoxic T cells appears to be an important mechanism in the development of obliteration in murine heterotopic tracheal allografts.

Intratracheal infection as an efficient route for testing vaccines against Chlamydia abortus in sheep.

Pregnant ewes have been widely used to test vaccines against Chlamydia abortus. However, this model entails many disadvantages such as high economic costs and long periods of pregnancy. The murine model is very useful for specific studies but cannot replace the natural host for the later stages of vaccine evaluation. Therefore, a non-pregnant model of the natural host might be useful for a vaccine trial to select the best vaccine candidates prior to use of the pregnant model. With this aim, two routes of infection were assessed in young non-pregnant sheep, namely, intranasal (IN) and intratracheal (IT). In addition, groups of non-vaccinated sheep and sheep immunised with an inactivated vaccine were established to investigate the suitability of the model for testing vaccines. After the experimental infection, isolation of the microorganism in several organs, with pathological and immunohistochemical analyses, antibody production assessment and investigation by PCR of the presence of chlamydia in the vagina or rectum were carried out. Experimental IT inoculation of C. abortus induced pneumonia in sheep during the first few days post-infection, confirming the suitability of the IT route for testing vaccines in the natural host. The course of infection and the resulting pathological signs were less severe in vaccinated sheep compared with non-vaccinated animals, demonstrating the success of vaccination. IN infection did not produce evident lesions or demonstrate the presence of chlamydial antigen in the lungs and cannot be considered an appropriate model for testing vaccines.