Predicting the depth of insertion of central venous catheters using a bronchoscopy-based carinal measurement technique or the Peres' formula-based method in adults undergoing cardiac surgery: A randomised comparative double-blind study

Background and aims: Various methods are used to predict the depth of insertion of central venous catheters (CVCs). We evaluated a bronchoscopy-based carinal measurement technique to predict this depth.

Methods: We randomised adults undergoing cardiac surgery into a bronchoscopy group or the Peres' formula-based method group. CVCs were inserted through the right internal jugular vein. The skin insertion reference point was at the level of the cricoid cartilage lateral to the carotid artery. In the bronchoscopy group, the depth of insertion was determined by the total length from the carina to the proximal end of the tracheal tube (TT) (measured with a flexible bronchoscope) minus (the sum of the distances from the skin insertion reference point to the TT and the length of the TT outside the mouth). In the Peres' group, height (cm)/10 determined the depth of insertion. Confirmation of CVCs' distal tip position was done with transoesophageal echocardiography. The area from 2 cm proximal to 1 cm distal to the superior vena cava-right atrium junction was considered ideal. The primary outcome was the proportion of correct CVC placements. The secondary outcome was the alignment of the CVCs.

Results: Forty-one patients in the bronchoscopy group and 40 patients in the Peres' group were enroled. A greater proportion of CVCs was placed correctly in the bronchoscopy group (87.8% vs. 37.5%; P = 0.001). A more significant proportion of CVC tips was abutting the vessel wall in the Peres' group (45% vs. 19.5%; P = 0.014).

Conclusion: Bronchoscopy-based carinal measurement technique results in more accurate placement of CVCs compared to the Peres' method.