The purpose of the present trial is therefore to assess effects of arginine vasopressin vs. saline placebo on hospital admission rate (primary end point), as well as hemodynamic variables, fluid resuscitation requirements and hospital discharge rate (secondary study end points) in presumed traumatic hemorrhagic shock patients with a systolic arterial blood pressure <90 mm Hg after 10 min of standard shock treatment. Accordingly, the study reflects an add-on design to standard traumatic shock therapy.

The hypothesis is that both arginine vasopressin and saline placebo have comparable effects on hemodynamic variables, fluid resuscitation requirements, and hospital admission and discharge rate. The alternative hypothesis is that arginine vasopressin has more beneficial effects on hemodynamic variables, fluid resuscitation requirements, and hospital admission and discharge rate than saline placebo.

The study will be designed as a multicenter, randomized, placebo-controlled clinical trial with blinded assessment of the outcome in a study network with helicopter emergency medical service units in Austria, Germany, Switzerland, Italy, Czech Republic and the Netherlands.

The protocol, information and consent procedure will be approved by the institutional review board of each participating center. Since this is a study randomizing unconscious patients who are unable to give informed consent at the time of randomization (§43a Emergency study), the requirement of informed consent is planned to be waived in accordance with the ethical standards of national legislation in Germany, Austria, Switzerland, Italy, Czech Republic and the Netherlands and the guidelines for good clinical practice of the European Agency for the Evaluation of Medicinal products. Depending on the patient's outcome, either the surviving patient, or the patient's family in case of death of the patient or in case that the patient survives but remains mentally handicapped will be informed about the trial (see appendix for patient information sheet); the protocol specifies that if there are any objections, the patient will be withdrawn from the study.

Treatment assignments of blinded study drugs will be randomly generated by computer in blocks of two, with stratification according to center. Before the start of the trial, staff at participating centers will be informed about the rationale of the protocol and the study; participating centers will be subsequently contacted and visited to ensure proper enrollment.

Inclusion Criteria:

• Adult trauma patients presenting with presumed traumatic hemorrhagic shock (systolic arterial blood pressure <90 mm Hg) that does not respond to the first 10 min of standard shock treatment [endotracheal intubation, crystalloid-, colloid-, and hypertonic saline (up to 4 ml/kg) fluid resuscitation, and catecholamine (ephedrine, phenylephrine, norepinephrine, epinephrine) vasopressors].

Exclusion Criteria:

• Terminal illness
• No intravenous access
• Age < 18 years
• Injury > 60 min before randomization
• Known pregnancy
• Cardiac arrest before randomization
• Presence of a do-not-resuscitate order
• Untreated tension pneumothorax
• Untreated cardiac tamponade
• Participation in another clinical study.