Morphological evaluation of the dilational tracheostomy procedure site and its impact on complications assessed by ultrasonography and fiberoptic bronchoscopy

Introduction: The term tracheostomy is used to create an opening in the trachea and secure the edges of the opening to the skin of the neck. 'Percutaneous' means 'through the skin.' The percutaneous method is a procedure performed at the bedside to provide an airway opening and ventilate the patient. The most common reason for tracheostomy in critically ill patients is the need for prolonged mechanical ventilation. Previous studies have often reported the intervention site as the 2nd to 4th tracheal cartilage intervals. Evaluation of the intervention site with Doppler ultrasound (USG) before percutaneous tracheostomy is recommended to prevent complications. The use of fiberoptic bronchoscopy (FOB) during the procedure can prevent possible misapplications and complications, but it is known to carry risks such as prolonged procedure time, hypoxemia, tracheal trauma, and bleeding. The primary aim of our study was to evaluate the impact of individuals' morphological structure on the intervention site and complications following percutaneous dilatational tracheostomy (PDT) using forceps dilatation method, guided by FOB and USG after determining the guide wire entry site based on anatomical landmarks. Our secondary aim was to determine optimal tracheostomy opening levels in patients with different morphological features and their relationship with complications. Materials and Methods: Our study was prospectively planned as an observational study. Patients aged 18 and older scheduled for PDT were included. Patients who refused to participate or provide consent for PDT, those with masses in the operation area, skin infections, coagulopathies, and oxygenation problems (positive end-expiratory pressure [PEEP] >15 cm H2O, fraction of inspired oxygen [FiO2] >0.80) were excluded. Neck perimeter measurements were taken from the thyroid prominence level and bilateral clavicular head levels while the patient's neck was in a neutral position before the procedure. After giving the patient the standard PDT position, anatomical measurements were performed with a flexible ruler. The intervention site was evaluated with USG, measuring the distance between the patient's skin and tracheal rings and the coronal diameter of the trachea during inspiration. The intervention site was determined by the operator based on standard anatomical marking. FOB was used for intratracheal observation during the PDT procedure. Procedure time, intervention site and number, complications during and after the procedure were recorded. All PDT procedures were performed by an intensive care specialist or an anesthesiology resident with at least 2 years of experience. All USG and FOB procedures were performed by the same anesthetist. Statistical analyses were conducted using SPSS 24.0, and a p-value less than 0.05 was considered statistically significant. Results: A total of 104 patients were evaluated for the study, but nine did not meet the inclusion criteria and the PDT procedure was cancelled in 4 patients. Consequently, data from 91 patients were collected and analyzed according to the study protocol. The average age was 57.3±19.7 years, with males comprising 72.5% of the patients. The average duration of mechanical ventilation before tracheostomy was 11.2±5.8 days. None of the demographic or neck measurement values were found to be decisive to provide consistency of USG presumption and FOB visualization for the tracheal space used. ROC analyses for anatomical measurements were performed based on the consistency of levels determined by FOB and USG. No ROC analyses were statistically significant, and none of the measurements were identified as a good predictor of the consistency between USG and FOB. In simple linear regression analyses comparing anatomical measurements with tracheostomy opening levels confirmed by FOB, statistically significant positive linear relationships were found between the tracheostomy opening level and the distances of cricoid cartilage-anatomical landmark, cricoid cartilage-jugular notch, mentum-jugular notch, and thyroid protuberance-jugular notch. A statistically significant negative linear relationship was found between the tracheostomy level and neck circumference measured from the level of the thyroid prominence. Regression formulas were created for tracheostomy levels based on anatomical measurements. Conclusion: In conclusion, the morphological features of patients influence the level of tracheostomies opened from the anatomical landmark level. As neck length increases, tracheostomy openings tend to be at more caudal levels, and as neck thickness increases, this level shifts cranially. There was significant discrepancy between the level presumed by USG and the level determined by FOB during the procedure. Using FOB during tracheostomy may create awareness in terms of complications and ensures midline and near-midline puncture. However, considering the risks of hypercarbia associated with respiratory acidosis, the use of bronchoscopy during PDT should be evaluated for each patient after assessing the risks and benefits. Cartilage fracture detected by FOB is a significant complication due to its potential to cause long-term tracheal stenosis. In our study, unlike many others, the most frequently observed intraoperative complication was noted to be cartilage fracture but not minor bleeding. Despite detailed research on morphological features associated with cartilage fracture, procedural practices, and practitioner experience, factors influencing the frequency of this complication could not be identified. Further studies are needed to evaluate the clinical significance of cartilage fracture. Considering the success rate of midline puncture (63.7%), the chance to ensure mid-line cannulation with repetetive punctions, the use of 2nd and 3rd intercartilageous spaces in a ratio of 74% and the absence of complications resulting from the site of trachea cannulation we believe that the anatomical landmark chosen, based on an imaginary line connecting the superior ends of both clavicle bones on the sternal side, can be used as a reliable method for PDT when USG or FOB guidance is not available.