The goal of this observational study is to examine the early hemodynamic effects and clinical outcomes of vasopressin use in patients with septic shock. The study aims to compare adult ICU patients who received norepinephrine alone versus those who received vasopressin in addition to norepinephrine.

The main question it aims to answer is:

Does adding vasopressin to norepinephrine improve blood pressure, lactate levels, and survival in patients with septic shock?

Researchers used retrospective medical records of patients treated between January and December 2024. Data such as blood pressure, heart rate, lactate levels, and mortality were collected and analyzed to assess treatment response and outcomes.

This is a single-center, retrospective observational cohort study designed to evaluate the clinical impact of adjunctive vasopressin therapy in adult patients with septic shock. The study protocol was developed to assess early hemodynamic responses and mortality outcomes associated with vasopressin use in real-world intensive care settings in Türkiye.

A total of 146 adult patients admitted to the intensive care unit (ICU) between January 1 and December 15, 2024, were included in the study. All patients fulfilled Sepsis-3 criteria for septic shock and received norepinephrine as the primary vasopressor agent. Among these, 33 patients received vasopressin in addition to norepinephrine, while the remaining patients were managed with norepinephrine alone.

The primary objective of the study is to describe early hemodynamic changes following vasopressin administration, specifically focusing on changes in:

Mean arterial pressure (MAP),

Heart rate (HR),

Serum lactate levels, and

Norepinephrine dose requirement,

within the first 6 and 24 hours of vasopressin initiation.

The secondary objective is to assess all-cause mortality among patients who received norepinephrine alone versus those treated with norepinephrine plus vasopressin.

All data were collected retrospectively from the institution's electronic health record system. Patients who received dopamine or epinephrine either prior to or concurrently with vasopressin were excluded to ensure homogeneity of the treatment groups. No randomization or prospective allocation was involved, and all treatment decisions were made by the clinical ICU team as part of routine medical care.

Statistical analyses will include descriptive and inferential methods to compare outcomes between the two groups, including Mann-Whitney U test, Chi-square test, Friedman's test, and Kaplan-Meier survival analysis. This study aims to describe the protocol and methodology of a real-world, retrospective analysis and does not intend to present prospective results at this stage.

The protocol was approved by the institutional ethics committee and adheres to international standards for human subject research.

Inclusion Criteria:

• Adult patients (≥18 years old) admitted to the intensive care unit (ICU)
• Diagnosed with septic shock according to Sepsis-3 criteria
• Treated with norepinephrine as the initial vasopressor
• Received norepinephrine alone or norepinephrine with adjunctive vasopressin
• Admitted between January 1 and December 15, 2024

Exclusion Criteria:

• Patients younger than 18 years
• Patients who received epinephrine or dopamine prior to or along with vasopressin
• Patients with incomplete clinical or hemodynamic data
• Readmitted ICU patients during the same hospitalization
• Patients with do-not-resuscitate (DNR) orders at ICU admission

Critically ill adult patients with septic shock admitted to the intensive care unit of a tertiary academic hospital in Türkiye. All participants received norepinephrine as a first-line vasopressor, and a subset received adjunctive vasopressin.

The dataset includes identifiable patient-level clinical data from a retrospective ICU cohort. Due to ethical and privacy considerations, individual participant data (IPD) will not be shared.