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Design of the study: 

A retrospective cohort study designed to evaluate whether the use of long-axis view ultrasound guidance to place femoral central venous lines (CVL) in neonates with cardiac disease would facilitate an increased success rate with fewer attempts and complications compared to the landmark technique.

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Methods:

115 neonates with cardiac disease who had direct observation of femoral CVL placement were included in the study. Of these, 76 had US guided placement and 39 had CVL placement by the landmark technique. Patients were excluded if the line placement was not directly observed. The outcomes evaluated included success rate, number of attempts, inadvertent arterial puncture, the development of venous or arterial thromboses and central line associated blood stream infections. The groups were similar in age, weight, and RACHS-1 score.

Results: With regard to follow up, the outcomes being analyzed were all short-term outcomes and with regard to infection it was only followed within 48 hours of the line placement. Patients were analyzed in the groups to which they were randomized. Of note, 12 of the ultrasound events included in the analysis were preceded by multiple failed attempts of the landmark method. Technically, these would be considered cross-over’s, but since the primary outcome involves observations about the insertion itself this only minimally affects validity. They do analyze these outcomes differently than "fresh" US attempts. 

Conclusions:

The overall success rate of CVL placement was lower in the landmark method as compared to the US-guided technique (79.5% vs. 97.4%) with an absolute risk increase of success of 15.2%. Successful CVL placement was 1.2 times more likely with US guidance as compared to the landmark method (95% CI 1.02-1.35). This increase in success with US-guidance also held true when 1st attempt and less than or 2 attempt success rates were analyzed separately. First attempt success was 2.4 times more likely (95% CI 1.5-4.2) and < 2 attempt success was 1.8 times more likely (95% CI 1.3-2.3) in the US-guided group.

In terms of complications arterial puncture was more likely with the landmark method as compared to the US-guided technique and there was a decreased risk of DVT with the US method.



Other interesting points:

There were significantly more intubated patients in the landmark group (100%) vs. 32% of patients in the landmark group. We don't know why some of these patients did not get the line placed preop which is the usual practice at the institution where the study took place. This could be a difference in the patient population, systematic bias, but it cannot be determined based on the information presented. 

Take home message:​
Overall, these results can be applied to our patient population but it is important to note that one of the limitations of this study is that they did not consider the time to successful line placement.