this retrospective study was approved by the institutional review board of our hospital ( 2014 - 09 - 037 ) . between november 2011 and october 2014 , 245 patients in the icu underwent bedside pdt with a ciaglia blue rhino percutaneous tracheostomy set ( cook medical , bloomington , in , usa ) due to prolonged endotracheal tube insertion . pdt was not performed in patients aged under 18 years , those with any pulsation palpated over the tracheostomy site , patients with a history of surgery or radiotherapy in the cervical region , and those with coagulopathy ( increased prothrombin time , inr > 2 ) . the first four procedures were performed by two physicians and one nurse using the standard technique , with one physician operating the bronchoscope while the other performed pdt . the next 55 procedures were performed by one physician and one nurse , with the physician using the bronchoscope only to confirm and evaluate the proper depth for the endotracheal tube before performing pdt using the simplified method described below . the remaining 186 procedures were performed using the simplified technique after repositioning the endotracheal tube at the predetermined depth ( 17 cm for males and 15 cm for females at the incisor ) . all pdts were performed by a single physician and one nurse , both of whom fully understood the entire procedure . the nurse administered sedatives and analgesics , as well as repositioning the endotracheal tube . except for patients with limited neck extension , a small pillow was placed under the patient 's shoulders to slightly extend the neck . transverse markings were made at the cricothyroid membrane and 2.0 cm toward the sternal notch ( fig . was also made in the midline of the trachea by holding the trachea between the thumb and index finger . the middle of the vertical mark intersected with the transverse mark 2.0 cm below the cricothyroid membrane ( fig . if the cricothyroid membrane could not be palpated , ultrasonography was used to identify the anatomic structures . the cricoid cartilage and tracheal rings were identified by placing the linear probe 45 degrees from the sagittal plane , and the area between the second and third tracheal rings was marked with a skin marker ( figs . the linear probe was positioned vertical to the trachea to confirm its midline ( figs . fio2 was increased to 1.0 , and 57 cmh2o positive end - expiratory pressure was applied to all patients receiving ventilator care . in patients who were receiving oxygen supplementation via a hydro - trach t - piece , the pdt site was disinfected with povidone iodine solution and a sterile drape was used before subcutaneously injecting 2% lidocaine . a vertical skin incision ( 1.5 cm ) was made through the midline vertical marking , and the endotracheal tube was withdrawn until the tube depth was 17 cm for males and 15 cm for females ( fig . 1d ) using a 5 cm - introducer needle , included in the cook ciaglia blue rhino set , and proper needle position was confirmed by air regurgitation with a syringe containing normal saline . the remaining pdt procedure was performed using the previous standard method with a # 7 tracheostomy tube ( twist , tracoe , germany ) . a # 8 tube was used only in patients in whom bronchoscopic lavage was planned ( about 10 patients ) . however , all 3 patients were receiving either extracorporeal membrane oxygenation or continuous renal replacement therapy and had an abnormal coagulation status . bleeding in all three long - term ( > 7 days ) follow - up in 150 patients showed no late complications and no deaths related to pdt . although use of a fob during pdt has been recommended for precise positioning and to avoid complications , bronchoscopy itself can cause complications . also , an additional physician is required and additional costs may result from damage to the fob . thus , several studies have assessed the safety of pdt without a fob , including technical modifications   and simplified procedures . direct visualization of the larynx with a laryngoscope confirmed adequate endotracheal tube repositioning depth prior to pdt , while direct or indirect palpation of the trachea confirmed the proper tracheostomy site . although these simplified techniques have been shown to be safe , they have not been widely adopted . this study assessed the safety of a simplified pdt technique using the ciaglia blue rhino , by repositioning the existing endotracheal tube at a pre - determined depth and determining proper pdt site by superficial palpation . early complications of pdt include loss of airway , bleeding , conversion to open tracheostomy and death , with later complications including tracheostomy occlusion , tracheal stenosis and granulation . a retrospective study comparing early and late complications of pdt , with or without fob assistance , using the ciaglia blue rhino kit in 243 patients found no between group differences in early and late complications , but one patient experienced cardiac arrest during the use of a fob due to loss of airway . in this study , only 3 patients experienced bleeding after pdt , with all 3 receiving extracorporeal membrane oxygenation or continuous renal replacement therapy and having an abnormal coagulation status . however , we were unable to assess long - term complications in patients who were transferred to other facilities . precise positioning is critical when performing pdt , thus requiring use of a fob or direct palpation of the trachea . the biggest disadvantage of our modified percutaneous method was the inability to confirm the pdt site . in five patients , where the underlying structures could not be adequately palpated another disadvantage is the lack of precise endotracheal tube repositioning , which can be achieved with a laryngoscope . although a fob was used to determine the proper tube depth in 55 patients , the needle and guidewire entered the murphy eye of the tube twice . pdt was successfully performed by retracting the tube an additional 12 cm in both cases . although none of these patients experienced endotracheal cuff failure due to needle puncture , accidental cuff puncture may occur . moreover , in contrast to subcutaneous dissection , physicians using our modified technique may be unable to identify vessels between the skin and trachea . ultrasonography , which was used when anatomical structures were not readily identifiable , also has the advantage of screening such blood vessels . since all pdts were performed at a single center by two physicians , and the proper endotracheal tube depth was evaluated in a korean population , it may be difficult to generalize the safety of our simplified technique . another limitation was the absence of patients in which pdt is believed to be difficult , such as patients with severe obesity . although studies have suggested that pdt is safe in obese patients , use of additional equipment , such as a fob or ultrasonograph , has been recommended . we have not performed pdt in morbidly obese patients who may also require extra - long tracheostomy tubes . currently , therefore , a fob should be used when performing pdt in difficult situations , such as in patients with morbid obesity , anatomic alterations or neck stiffness . in conclusion , our results show that pdt with the ciaglia blue rhino technique can be safely performed without a bronchoscope and blunt dissection . this simplified technique is a relatively safe procedure that can be especially useful in situations of limited equipment and medical personnel .
when first introduced , percutaneous dilatational tracheostomy ( pdt ) was performed using a bronchoscope . 
 the bronchoscope itself , however , has several disadvantages , including interruption of ventilation . 
 modifications of the standard pdt technique have suggested that pdt can be safely performed without a bronchoscope . 
 however , the safety of these modifications is unclear and many modifications have yet to be widely adopted . 
 this study retrospectively evaluated the safety of a simplified pdt technique using the cook ciaglia blue rhino in 186 patients . after confirming the underlying structures by palpation 
 , pdt was performed without a bronchoscope or blunt dissection , 2.0 cm below the cricothyroid membrane . 
 ultrasonography was used only when palpation was difficult . except for bleeding in three patients with coagulopathy 
 , none of the patients experienced any early or late complications , and there were no deaths related to pdt . 
 these findings confirm that pdt can be safely performed using a simplified technique , which may be useful in situations with limited equipment and medical personnel .