In the July issue of Critical Care Medicine, Fragou et al present data from a prospective, unblinded, single-center randomized trial examining the use of real-time ultrasound for cannulation of the subclavian vein. The study included 401 patients receiving mechanical ventilation who required subclavian central venous cannulation (SCV). Patients were being treated at a tertiary multidisciplinary intensive care unit (ICU) in Athens, Greece. The experimental group consisted of 200 patients who had SCV cannulation under real-time ultrasonographic (US) guidance versus 201 patients cannulated using the traditional landmark method. Patients converted from the control group to the US group during the study were excluded from the primary analysis.

The US group had a statistically significantly higher success rate (100% vs. 87.5%, p< 0.05), shorter access time (26.8 minutes vs. 44.8 minutes, p< 0.05), and fewer complications. There were no pneumothoraces or hemothoraces in the US group; the number needed to treat to prevent one pneumothorax or inadvertent arterial puncture was 20 (0% in US group vs. 4.9% in landmark group). The mean number of attempts was lower in the US group (1.1 ± .3 vs. 1.9 ± .7). Catheter misplacement was not significantly different between the two groups.

Limitations to this work include a limited sample size and no description of a priori power calculations for each of the outcome measures. The incidence of pneumothorax with SCV cannulation using landmark techniques varies in the literature and was observed to be 4.9% in this study, which many would consider to be moderately high. The US approach may have been associated with fewer complications since the insertion site was more lateral, and the axillary vein, rather than the SCV, might have been the initial insertion site for some of the patients. Although all cannulations were performed by physicians with at least six years of ICU experience, US-guided SCV cannulation was deemed to be technically difficult as assessed by a postprocedural semiquantitative scale.

While US-guided internal jugular cannulation has become a standard of care in many ICUs, US-guided SCV cannulation has yet to be validated and accepted as a routine technique. Results of this study suggest that US-guided SCV cannulation is feasible (although technically difficult), and it may help prevent complications, including pneumothorax.

Concise Critical Appraisal is a regular feature in the Society of Critical Care Medicine’s eNewsletter. Authored by Samuel M. Galvagno Jr., DO. Each installment highlights journal articles most relevant to the critical care practitioner.