The aim of this observational study is to examine real-world clinical practice regarding the use of vasopressin as a second-line vasopressor in adult patients admitted to Intensive Care Units (ICUs) with septic shock.

The study focuses on critically ill adults (≥18 years) diagnosed with septic shock and treated with norepinephrine and vasopressin.

The main research questions are:

• Does early initiation of vasopressin-defined by the norepinephrine dose at the time of introduction-reduce mortality in patients with septic shock?
• What is the impact of vasopressin as a second vasopressor on renal function and the progression of organ dysfunction in septic shock patients?

Participants will:

• Be admitted to an ICU with a diagnosis of septic shock.
• Receive vasopressin as an adjunct to norepinephrine for hemodynamic support.
• Be monitored daily throughout their ICU stay, with data collected through a dedicated REDCap system.
• Have relevant clinical data pseudonymized and incorporated into the study database for statistical analysis.

Eligible patients for this study must comply with the following requirements.

• ICU admission with a septic shock diagnosis.
• Age 18 years or above at ICU admission.
• Use of vasopressin as an adjunct of norepinephrine.

For the purposes of this study, septic shock is defined by full compliance with the following criteria.

• Sustained arterial hypotension or serum lactate above 2 mmol/L.
• Adequate but unsuccessful fluid resuscitation.
• Vasopressor usage to maintain a mean arterial pressure above 65 mmHg.
• Probable or proven infectious etiology.

Patients with some of the following conditions will be automatically excluded.

• Pregnancy.
• Ischemic cardiogenic shock.
• Acute intestinal ischemia.
• Readmission to the Intensive Care Unit.

ICU-admitted patients treated at Spanish public hospitals participating in the study.

The study protocol agreed upon with the supervising authorities explicitly excludes the possibility of doing so.