Renin, Angiotensin II, and the Journey to Evidence-based Individual Treatment Effects

Angiotensin II treatment is associated with improved oxygenation in ARDS patients with refractory vasodilatory shock

BACKGROUND

The physiological effects of renin-angiotensin system modulation in acute respiratory distress syndrome (ARDS) remain controversial and have not been investigated in randomized trials. We sought to determine whether angiotensin-II treatment is associated with improved oxygenation in shock-associated ARDS.

METHODS

Post-hoc subgroup analysis of the Angiotensin Therapy for High Output Shock (ATHOS-3) trial. We studied patients who met modified Berlin ARDS criteria at enrollment. The primary outcome was PaO2/FiO2-ratio (P:F) at 48-h adjusted for baseline P:F. Secondary outcomes included oxygenation index, ventilatory ratio, PEEP, minute-ventilation, hemodynamic measures, patients alive and ventilator-free by day-7, and mortality.

RESULTS

Of 81 ARDS patients, 34 (42%) and 47 (58%) were randomized to angiotensin-II or placebo, respectively. In angiotensin-II patients, mean P:F increased from 155 mmHg (SD: 69) at baseline to 265 mmHg (SD: 160) at hour-48 compared with no change with placebo (148 mmHg (SD: 63) at baseline versus 164 mmHg (SD: 74) at hour-48)(baseline-adjusted difference: + 98.4 mmHg [95%CI 35.2-161.5], p = 0.0028). Similarly, oxygenation index decreased by - 6.0 cmH2O/mmHg at hour-48 with angiotensin-II versus - 0.4 cmH2O/mmHg with placebo (baseline-adjusted difference: -4.8 cmH2O/mmHg, [95%CI - 8.6 to - 1.1], p = 0.0273). There was no difference in PEEP, minute ventilation, or ventilatory ratio. Twenty-two (64.7%) angiotensin-II patients had sustained hemodynamic response to treatment at hour-3 versus 17 (36.2%) placebo patients (absolute risk-difference: 28.5% [95%CI 6.5-47.0%], p = 0.0120). At day-7, 7/34 (20.6%) angiotensin-II patients were alive and ventilator-free versus 5/47(10.6%) placebo patients. Day-28 mortality was 55.9% in the angiotensin-II group versus 68.1% in the placebo group.

CONCLUSIONS

In post-hoc analysis of the ATHOS-3 trial, angiotensin-II was associated with improved oxygenation versus placebo among patients with ARDS and catecholamine-refractory vasodilatory shock. These findings provide a physiologic rationale for trials of angiotensin-II as treatment for ARDS with vasodilatory shock.

TRIAL REGISTRATION

ClinicalTrials.Gov Identifier: NCT02338843 (Registered January 14th 2015).

Angiotensin II: A Review of Current Literature

Up to one-third of all patients admitted to intensive care units carry a diagnosis of shock. The use of angiotensin II is becoming widespread in all forms of shock, including cardiogenic, after the U.S. Food and Drug Administration's (FDA's) initial approval for vasoplegic shock in 2017. Here, the authors review the literature on angiotensin II's mechanism of action, benefits, and future therapeutic opportunities.