Clinical question: Does the use of arterial catheters (AC) improve hospital mortality in ICU patients requiring mechanical ventilation?
Background: AC are used in 40% of ICU patients, mostly to facilitate diagnostic phlebotomy (including arterial blood gases) and improve hemodynamic monitoring. Despite known risks (limb ischemia, pseudoaneurysms, infections) and costs necessary for insertion and maintenance, data regarding their impact on outcomes are limited.
Study design: Propensity-matched cohort analysis of data in the Project IMPACT database.
Setting: 139 ICUs in the U.S., with larger and urban hospitals providing the majority of the data.
Synopsis: Of 60,975 medical patients who required mechanical ventilation, 24,126 (39.6%) patients had an AC. Propensity score matching yielded 13,603 pairs of patients who did not have an AC with patients who did have an AC. For many variables that could influence mortality in such patients, there were no significant differences between the two groups. No association between AC use and hospital mortality in medical ICU patients who required mechanical ventilation was noted. This was confirmed in analyses of eight of nine secondary cohorts. In one cohort (patients requiring vasopressors), AC use was associated with an 8% increase in the odds of death. More blood transfusions were administered in the AC group, although this finding did not reach statistical significance.
Despite the rigorous and complex statistical analysis used in this study, residual confounders remained. It is still possible, but unlikely, that patients with an AC could have had a higher expected mortality, which the use of the AC ameliorated. This study raises an important question that should ideally be addressed by randomized trials.
Bottom line: Arterial catheters used in mechanically ventilated patients in the ICU are not associated with lower mortality and should therefore be used with caution, weighing the risks and benefits, until more studies are performed.
Citation: Gershengorn HB, Wunsch H, Scales DC, Zarychanski R, Rubenfeld G, Garland A. Association between arterial catheter use and hospital mortality in intensive care units. JAMA Intern Med. 2014;174(11):1746-1754.