Noninferiority of Deferring Early Arterial Catheterization in Shock Management: Insights from a Multicenter RCT

Highlight

• Deferring early arterial catheter insertion in shock patients is noninferior to early invasive monitoring regarding 28-day mortality.
• Noninvasive automated brachial cuff blood pressure monitoring was effective and safe, allowing delayed catheterization as needed.
• Arterial catheter-related complications such as hematoma and hemorrhage were significantly reduced with a noninvasive-first strategy.
• Patient discomfort related to monitoring devices was slightly higher in the noninvasive group but clinically manageable.

Study Background

Shock is a life-threatening condition characterized by inadequate tissue perfusion leading to organ dysfunction. Continuous and accurate hemodynamic monitoring, particularly arterial blood pressure measurement, is critical for managing shock effectively. The current clinical guidelines often recommend invasive arterial catheterization (arterial line) as the gold standard for blood pressure monitoring in critically ill shock patients due to its real-time accuracy and reliability. However, invasive monitoring carries risks such as bleeding, hematoma, infection, and patient discomfort. The potential exists for automated noninvasive blood-pressure monitoring devices, such as brachial cuffs, to serve as initial monitoring tools, deferring or avoiding early arterial catheter insertion. Yet, whether this practice compromises patient outcomes remains unclear, representing an important clinical question balancing safety, efficacy, and resource utilization in critical care.

Study Design

This was a pragmatic, multicenter, open-label, randomized controlled noninferiority trial conducted across intensive care units (ICUs). Eligibility criteria included adult patients admitted within 24 hours requiring shock management. Patients were randomized to two strategies:

• Invasive strategy: Early insertion of an arterial catheter within 4 hours of randomization.
• Noninvasive strategy: Initial monitoring with automated brachial cuff blood pressure measurement, with arterial catheter insertion deferred unless prespecified safety criteria were met subsequently.

The primary outcome was all-cause mortality at day 28, with a noninferiority margin set at 5 percentage points. Secondary outcomes included safety events related to blood-pressure-monitoring device use (e.g., hematoma, hemorrhage), and patient-reported pain or discomfort associated with the monitoring device. Both intention-to-treat and per-protocol analyses were performed to assess the robustness of results.

Key Findings

A total of 1010 patients were randomized, with 504 assigned to the noninvasive strategy group and 502 to the invasive strategy group. Notably, 14.7% (74 patients) in the noninvasive group required arterial catheter insertion later due to clinical indications, whereas 98.2% (493 patients) in the invasive group had early catheter insertion as per protocol.

Primary Outcome – Mortality: At day 28, mortality occurred in 34.3% of patients in the noninvasive group versus 36.9% in the invasive group. The adjusted risk difference was -3.2 percentage points with a 95% confidence interval ranging from -8.9 to 2.5, meeting the criteria for noninferiority (P = 0.006). Per-protocol analyses yielded consistent findings.

Device-Related Adverse Events and Patient Comfort: Hematoma or hemorrhage related to arterial catheter insertion occurred significantly more in the invasive group (8.2%) compared to the noninvasive group (1.0%). Conversely, pain or discomfort associated with the ongoing presence of the blood pressure monitoring device was somewhat higher in the noninvasive group (13.1%) versus the invasive group (9.0%), possibly reflecting cuff inflation discomfort or frequent noninvasive measurements.

These findings indicate that early deferral of arterial catheterization with a noninvasive monitoring-first approach is safe and does not increase mortality risk in patients with shock. Importantly, this strategy reduces catheter-related mechanical complications without compromising hemodynamic monitoring effectiveness in most cases.

Expert Commentary

This robust, high-quality trial addresses a pivotal question in shock management, challenging the longstanding clinical paradigm that early arterial catheter insertion is mandatory. The preservation of survival with a noninvasive-first strategy suggests that many patients can be monitored safely without early invasiveness, reserving arterial catheterization for those who clinically deteriorate or meet safety criteria. Such an approach may minimize iatrogenic harms, reduce ICU workload related to catheter care, and improve patient comfort.

Limitations include the open-label design, which is unavoidable due to the nature of interventions, and potential variability in threshold criteria for delayed catheter insertion. Further subgroup analyses could explore specific shock etiologies or severity strata. Moreover, the trial was conducted in specialized tertiary centers, which may affect generalizability to other settings.

These findings align with a growing emphasis on minimizing unnecessary invasive procedures in critical care when feasible and safe, promoting a tailored monitoring approach balanced with patient-centered outcomes.

Conclusion

In critically ill patients with shock, a strategy of deferring early arterial catheterization in favor of initial noninvasive automated blood pressure monitoring is noninferior to early invasive arterial catheter insertion in terms of 28-day mortality. This approach effectively reduces arterial catheter-related complications without compromising patient safety, supporting a shift towards more conservative invasive monitoring use guided by clinical needs and safety criteria.

Funding and ClinicalTrials.gov

This study was funded by the French Ministry of Health. ClinicalTrials.gov identifier: NCT03680963.

References

Muller G, Contou D, Ehrmann S, Martin M, Andreu P, Kamel T, Boissier F, Azais MA, Monnier A, Vimeux S, Chenal A, Nay MA, Salmon Gandonnière C, Lascarrou JB, Roudaut JB, Plantefève G, Giraudeau B, Lakhal K, Tavernier E, Boulain T; CRICS-TRIGGERSEP F-CRIN Network and the EVERDAC Trial Group. Deferring Arterial Catheterization in Critically Ill Patients with Shock. N Engl J Med. 2025 Oct 29. doi: 10.1056/NEJMoa2502136. Epub ahead of print. PMID: 41159885.