Highlight
– Refractory septic shock defined by high vasopressor dose plus persistent tissue hypoperfusion predicts markedly higher 28-day mortality compared to vasopressor dose alone.
– Combining capillary refill time and lactate trends with norepinephrine equivalent dose at 6 hours improves prognostic accuracy.
– Patients meeting both tissue hypoperfusion criteria had a 73.6% mortality rate, significantly exceeding that of patients classified by vasopressor dose alone.
– This biomarker-integrated risk stratification may guide early aggressive interventions and clinical trial enrichment.
Study Background
Septic shock remains a leading cause of mortality in intensive care units worldwide, characterized by distributive shock and profound circulatory failure. Despite advances in sepsis management, refractory septic shock—where patients remain hemodynamically unstable despite adequate fluid resuscitation and escalating vasopressor support—has an especially poor prognosis. Identifying patients at highest risk for death early remains challenging but crucial for tailoring therapeutic strategies and clinical trial designs.
Traditionally, refractory septic shock is operationalized by vasopressor dose thresholds, such as norepinephrine equivalent dose (NEE) exceeding 0.5 µg/kg/min. However, vasopressor dose alone does not fully capture tissue-level perfusion abnormalities which may drive organ failure and mortality. Persistent tissue hypoperfusion, reflected by non-normalizing lactate levels and prolonged capillary refill time (CRT), signals ongoing microcirculatory impairment that can worsen outcomes.
The ANDROMEDA-SHOCK-2 trial previously explored resuscitation guided by capillary refill time and lactate clearance. This secondary analysis investigates whether integrating persistent tissue hypoperfusion criteria with vasopressor dose enhances mortality risk stratification in patients with early septic shock beyond reliance on vasopressor dose alone.
Study Design
This exploratory secondary analysis included 1363 patients enrolled in the ANDROMEDA-SHOCK-2 randomized multicenter trial. Patients with septic shock underwent protocolized hemodynamic resuscitation focused on optimizing tissue perfusion parameters during the initial 6 hours.
Refractoriness was defined at 6 hours post-resuscitation as NEE >0.5 µg/kg/min combined with persistent tissue hypoperfusion. Two tissue hypoperfusion criteria were used: abnormal capillary refill time (>3 seconds) and non-decreasing blood lactate (failure to decrease on serial measurements). Patients were stratified using two approaches:
1. Both hypoperfusion criteria present (CRT >3 s and non-decreasing lactate).
2. At least one hypoperfusion criterion present (CRT >3 s or non-decreasing lactate).
The primary outcome was 28-day mortality, with secondary outcomes including days alive and free from life support.
Key Findings
Of 1363 patients analyzed, 188 (13.8%) had a NEE >0.5 µg/kg/min at 6 hours with a high mortality rate of 47.9%. When applying tissue hypoperfusion criteria, two classifications emerged:
- With both hypoperfusion criteria present, 53 patients (3.9%) were identified as having refractory septic shock, exhibiting an alarmingly high 28-day mortality of 73.6% versus 23.7% in non-refractory patients (adjusted hazard ratio [aHR] 4.68; 95% CI 3.31–6.64; p < 0.001).
- When using the criterion of at least one hypoperfusion marker, 124 patients (9.1%) were classified as refractory, with 55.0% mortality compared to 22.7% for those non-refractory (aHR 2.62; 95% CI 1.90–3.46; p < 0.001).
Patients classified as refractory under either hypoperfusion-based approach had significantly fewer days alive without life support, indicating greater morbidity.
Importantly, combining vasopressor dose with tissue hypoperfusion markers substantially improved prognostic enrichment for 28-day mortality. The two-hypoperfusion criteria model showed a positive likelihood ratio (LR+) of 8.12 (95% CI 4.70–14.03), markedly outperforming the vasopressor threshold alone (LR+ 2.71; 95% CI 2.10–3.50; p < 0.001).
Expert Commentary
This secondary analysis provides compelling evidence that integrating persistent tissue hypoperfusion assessment with vasopressor requirement better characterizes refractory septic shock early in the disease course. The use of accessible bedside measures such as capillary refill time complements biochemical lactate monitoring, together providing a more comprehensive picture of microcirculatory status than vasopressor dose alone.
From a pathophysiological standpoint, vasopressors restore macrocirculation but do not guarantee tissue perfusion normalization. Persistent hypoperfusion despite high-dose vasopressors signals microcirculatory failure and cellular dysoxia, which drive organ dysfunction and mortality. Identifying these patients can prompt consideration of adjunctive therapies and individualized hemodynamic targets.
Limitations of this study include its post hoc exploratory nature, potential variability in CRT measurement, and the confined timepoint of assessment at 6 hours which may not capture dynamic perfusion changes. External validation in independent cohorts and prospective interventional studies are needed to confirm whether this combined definition translates into clinical benefit by enabling earlier and more aggressive interventions.
Conclusion
In patients with early septic shock, combining persistent tissue hypoperfusion—characterized by prolonged capillary refill time and stagnant lactate clearance—with high vasopressor dose improves mortality risk stratification beyond vasopressor dose alone. This approach identifies a high-risk subset with markedly increased 28-day mortality and fewer days free from life support. These results support the clinical relevance of tissue perfusion assessment in conjunction with vasopressor requirements and encourage incorporation of bedside perfusion markers into definitions and management strategies for refractory septic shock. Further validation studies are essential to establish clinical utility and impact on therapeutic decision-making.
Funding and Clinical Trial Registration
The ANDROMEDA-SHOCK-2 trial and its subsequent analyses were conducted by the ANDROMEDA-Research Network with funding sources not specified in the original report. The original trial registration and detailed funding information can be accessed through the corresponding clinical trial registry and published protocol.
References
- Kattan E, Ospina-Tascón GA, Orozco N, et al. Persistent tissue hypoperfusion improves risk stratification beyond vasopressor dose in refractory septic shock: a secondary analysis of the ANDROMEDA-SHOCK-2 trial. Intensive Care Med. 2026 Jul 15; PMID: 42467247.
- Vincent JL, De Backer D. Circulatory shock. N Engl J Med. 2013 Jan 17;368(6):558-69.
- Jansen TC, van Bommel J, Schoonderbeek FJ, et al. Early lactate-guided therapy in ICU patients: a multicenter, open-label, randomized controlled trial. Am J Respir Crit Care Med. 2010 May 1;182(6):752-9.
- Hernandez G, Ospina-Tascón GA, Damiani LP, et al. Effect of a Resuscitation Strategy Targeting Peripheral Perfusion Status vs Serum Lactate Levels on 28-Day Mortality Among Patients With Septic Shock: The ANDROMEDA-SHOCK Randomized Clinical Trial. JAMA. 2019 Jan 8;321(7):654-664.
