Another alternative to universal certodyn adaptor.

Sir,

Central venous catheter (CVC) placement using endocavitary electrocardiogram (ECG) is a reliable method for correct insertion length estimation without increasing the insertion time.[1] It facilitates correct placement while avoiding complications related to over insertion. Such a placement requires a specific Certodyn adapter which is attached to a J-tipped CVC ensheathed guide wire. Institutional policies and financial constraints related to purchase of specific instrument/adapter for this technique limit its use by the willing anaesthesiologist.

We have designed an assembly at our institute which is simple to use, does not require a costly adapter, and gives reasonably good results. We have used an ethylene oxide sterilized copper wire to transduce the ECG from the ensheathed J-tip of the guide wire. Two ECG electrodes are stuck together by their sticky side. The ECG leads of the monitor are attached to the surface electrodes in a usual pattern except for the right arm lead, which is attached to the metallic tip on one side of the stuck electrodes of the electrode wire assembly. The electrode wire assembly is formed by interposing the copper wire between the stuck ECG electrodes and the din-pin of the electrode cable available with CVC set. One end of the copper wire is rounded and fitted to the metallic tip of the stuck electrodes, opposite to the attachment of right arm lead and the other end is fitted into the dinpin of the CVC electrode cable [Figure 1]. The guide wire length at which the J-tip is just outside the CVC is measured and marked using a sterile marker. The CVC catheter is inserted as per the recommended Seldinger's technique. The CVC is inserted up to the 14-15 cm mark over the guide wire. The guide wire was then gently withdrawn till the measured mark, marked using a sterile marker prior to insertion of introducer needle, was at the connector end of the distal port of CVC. The clip of the electrode cable is then applied on the guide wire at the measured mark to complete the assembly [Figure 2]. The CVC catheter along with the guide wire was now adjusted as guided by the P wave morphology on ECG in lead II. The CVC along with the guide wire was gently withdrawn when peaked P waves were seen in the monitor and fixed at a point when P wave morphology became normal. All ports were aspirated for blood and ease of flushing of saline was assessed. Correct placement of CVC catheter was defined as the tip of the catheter lying at +/−0.5 cm from the carina in the vertical plane as assessed by post-procedural chest x-ray.

Figure 1

Copper wire cable assembly. Black arrow pointing at the two electrocardiogram electrodes stuck together. White arrow pointing at the copper wire attached at one end to the snap end and at the other end to the din-pin of the electrode cable

Figure 2

Predetermination of length of guide wire at which the clip of electrocardiogram cable is to be applied. Black arrow pointing at the J tip of the guide wire protruding from the proximal CVC catheter port. White arrow pointing at the sterile marker used to mark the point of application of the clip

We have used this assembly in 14 consecutive cases to guide CVC insertion. We were successful in correct placement of CVC catheter tip in 13 out of 14 patients.

The principle of our assembly is similar to the Certodyn adapter. The Certodyn adapter is replaced here by the electrode wire assembly attached to the electrode cable. Presence of peaked P waves indicates presence of Jtip in the right atrium and gentle withdrawal till P waves become normal indicate its tip just above the right atrium, above the cephalic limit of pericardial reflection.[2]

A similar assembly has been devised by Jain et al.,[3] who mentioned the alternative to Certodyn adapter as a steel paper clip. We have used a copper wire, which being a better conductor of current (conductivity >30 times more than that of steel)[4] is possibly a better alternative. Also, they had kept the tip of guide wire at the tip of the CVC, while the Certodyn adapter technique recommends keeping the J-tip outside the CVC so that proper stimulation can be observed. The authors fixed the CVC at arbitrary 2 cm less than the site of appearance of normal P wave morphology which has not been justified. Also postprocedural confirmation using chest x-ray was not done.

Our preliminary report suggests that the described assembly may be a useful alternative to the costly Certodyn® Universal Adapter B. Braun Melsungen AG adapter in institutions where this is not readily available and helps in accurate placement of the CVC avoiding any complications due to overinsertion.

We would like to say again that ours is an experimental exercise and we recommend further evaluation of this technique against established methods based on anatomical landmarks and length of insertion, that are well-established in practice, for ease of insertion, time taken, and accuracy of placement.