Assessing the utility of ultrasound guided vascular access placement with longer catheters in critically ill pediatric patients
August 2023 by Dr K C Law
This is a retrospective single-center cohort study looking at using ultrasound to place longer length peripheral intravenous cannulae to prolong its indwelling life-span and use, increase placement success rate, and decrease need for multiple further cannulation events.
The 187 study sample came from Pediatric Critical Care Department, Pediatric Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA, which is a tertiary 25-bed mixed cardiac and pediatric intensive care unit. 88 patients received standard cannulae which were 1.9cm 24G, 2.5cm 22G, and 3.2cm 20G, and these were placed ‘traditionally’ using landmarks, vein palpation, and use of vein illuminator device. The other 99 patients were identified by ICU nurses as difficult cannulation at their discretion, often after two failed attempts using traditional cannulation approach; these patients had a longer length cannula placed using ultrasound (US) guidance done by vascular access team or intensivists with cannulae used being one of 3.2cm 24G, 4.4cm 22G, or 4.4cm 20G.
The majority of traditional approach placement sites were on the hand (31 cases), forearm (23 cases) and foot (20 cases), while the majority of the US-guided placements were on the forearm (55 cases) and upper arm (36 cases). Interestingly, the median age for the traditional group was 10 months, and for US group were 58 months, with 33 months as median age for the overall sample.
The median catheter in-dwelling time for the longer cannulae was 219 hours versus 108 hours for the traditional cannulae. Patients in the traditional group were also more likely to have their cannulae “fail”, needing further cannulation when adjusted to length of hospital stay. However, there are cannulae in both groups that survived over 300 hours. Reasons for cannulae removal included therapy completion, infiltration, impaired catheter integrity, site tenderness, catheter leak, accidental removal, occlusion, and bleeding at insertion site. Complication rates and need for central line placements were similar between the two groups.
Take Home Message / Commentary
This is an interesting study that looked at intravenous cannulation, which is inarguably one of the commonest invasive procedure performed in hospital. The study is laudable for raising questions on technique, possible improvement indicators, and inquiring on the patient experience dimension.
The stated study limitations include a lack of measurable criteria used to identify difficult venous access, lack of documentation on number of attempts before successful cannulation, potential bias from the (perhaps surprisingly) greater number of older-aged children in the US group, the absence of causal-relationship analysis between the type of medication/infusion with cannulae longevity, and potential operator bias from the separate vascular access team being wholly responsible for traditional cannulation and the US group mainly done by intensivists.
In addition to these stated study limitations, it would be useful to know if other factors influence cannula longevity such as make and design of cannulae used; the length or portion of cannulae inside the vessel; the size of vessel relative to diameter of cannulae used and its association, if any, with thrombosis; influence of type of cannulae care such as interrupted flushing technique with saline after cannula access; and patient/carer satisfaction. These data would help cannulation decision with regards to factors like type of cannula, site, approach, and aftercare needed.
Overall, this is a useful paediatric study lending weight to the argument for incorporating routine use of ultrasound for vascular access. The routine use of midline cannulae to increase cannulae longevity is less clear-cut due to other potential confounders not being accounted for in this study, but nevertheless, is useful as reflection to look for methods to further improve peripheral venous cannulation.