Problems with saline flush for arterial lines

Gupta and Cook's case report 1 highlighting neuroglycopenia due to accidental use of a glucose-containing arterial flush solution questions the effectiveness of the 2008 National Patient Safety Agency (NPSA) recommendations 2. Leslie et al.'s related national survey, in which 30% of respondents were aware of a local incident concerning incorrect arterial flush solution, reinforces these concerns 3. However, the NPSA recommendation to use only saline 0.9% as a flush solution may also result in morbidity for patients in intensive care units (ICUs) by prohibiting the use of heparinised solutions to only 4.6% of UK adult ICUs 3. The North Western Learning and Development Group of the Association of North-Western Intensive Care Units (ANWICU kNOWLEDGe) performed a prospective observational study at eight member hospitals in 2012. Data from 445 arterial catheters inserted over one calendar month in unselected medical and surgical patients in ICU showed that catheters flushed with heparinised solutions (n = 151; 34%) had a significantly increased median lifespan of 102 h, compared with 72 h for saline-only flushed catheters (n = 294; 64%, p < 0.01). There was a significant decrease in the likelihood of the need to remove a line due to blockage in the heparinised group (n = 12; 7.9%) compared with the saline group (n = 121; 41.2%, p < 0.0001). Using multiple logistic regression analysis, the odds ratio for the likelihood of blockage when using saline was 19.9 (95% CI 6.6–59.8), with line survival as demonstrated in Fig. 2. Our simple study has methodological limitations, but the results clearly highlight what most units in our region report anecdotally: changing to saline-only flushed lines leads to more arterial line failures. This is important because catheter thrombosis may lead to inaccurate blood pressure measurement, patient discomfort due to repeated reinsertion, damage to local structures and even distal ischaemia. Previous evidence in this area is limited; the largest study 4, which included over 5000 patients, supported a beneficial effect of heparin although it was methodologically unsound, with no blinding. Smaller studies have shown contradictory results 5-7. We suggest that there is justification for further detailed investigation of the effects of heparinised arterial flush solutions on thrombosis rates. An Association of Anaesthetists of Great Britain and Ireland Working Party has examined some of the patient safety issues highlighted concerning incorrect arterial flush solutions 8. The debate should also focus on what the correct flush solution should be, as saline-based solutions may well be causing significant problems of their own.