Do pressors (vasopressors) help in traumatic hypotension?

From the Guidelines

Pressors are not recommended as the primary treatment for traumatic hypotension, and their use should be carefully considered after addressing the underlying cause of shock and ensuring adequate volume resuscitation. The current approach to managing traumatic hypotension emphasizes restricted volume replacement and permissive hypotension, aiming to achieve a reduced systolic blood pressure of 80–90 mmHg in patients without traumatic brain injury (TBI) or spinal injury, as supported by recent meta-analyses of RCTs 1. This strategy is based on the concept that aggressive fluid resuscitation can lead to increased mortality, coagulopathy, and multiorgan failure, as demonstrated by several retrospective studies 1.

Key considerations in the management of traumatic hypotension include:

• Rapid bleeding control to prevent further volume loss
• Restricted volume replacement to avoid over-resuscitation and its associated complications
• Permissive hypotension to maintain a balance between tissue perfusion and the risk of exacerbating bleeding
• Careful consideration of the patient's underlying conditions, such as TBI, spinal injury, or chronic arterial hypertension, which may require a different approach

If pressors are considered necessary after adequate volume resuscitation has failed to restore hemodynamic stability, norepinephrine is typically the preferred agent, starting at 0.05-0.1 mcg/kg/min, titrated to effect, due to its balanced alpha and beta effects with less reduction in splanchnic blood flow 1. However, the use of pressors should be guided by invasive hemodynamic monitoring and a thorough understanding of the patient's underlying physiology to avoid compromising tissue perfusion.

From the FDA Drug Label

1 INDICATIONS & USAGE Vasopressin injection is indicated to increase blood pressure in adults with vasodilatory shock who remain hypotensive despite fluids and catecholamines.

12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Vasopressin causes vasoconstriction by binding to V1 receptors on vascular smooth muscle coupled to the Gq/11-phospholipase C-phosphatidyl-inositol-triphosphate pathway, resulting in the release of intracellular calcium.

In patients with vasodilatory shock vasopressin in therapeutic doses increases systemic vascular resistance and mean arterial blood pressure and reduces the dose requirements for norepinephrine.

The use of pressors like vasopressin may help increase blood pressure in patients with vasodilatory shock who remain hypotensive despite fluids and catecholamines. However, the provided drug labels do not directly address the use of pressors in traumatic hypotension.

• The labels specifically mention vasodilatory shock, not traumatic hypotension.
• There is no direct information on the effectiveness of pressors in traumatic hypotension. 2 2

From the Research

Traumatic Hypotension and Pressors

• The use of pressors in traumatic hypotension is a topic of interest, with various studies examining their effects on spinal cord perfusion and patient outcomes 3, 4, 5, 6.
• A study published in 2015 found that vasopressor usage in patients with acute traumatic central cord syndrome was associated with complication rates similar to those reported in the literature for spinal cord injury, with dopamine being associated with a higher risk of complications in patients over 55 years old 3.
• Another study published in 2021 suggested that norepinephrine may be the vasopressor of choice for augmenting spinal cord perfusion in patients with acute traumatic spinal cord injury, and that the combination of mean arterial pressure elevation and cerebrospinal fluid drainage may improve neurologic outcome more than either intervention alone 4.
• A porcine model study published in 2018 found that norepinephrine promoted better restoration of blood flow and oxygenation to the traumatically injured spinal cord compared to phenylephrine 5.
• A retrospective cohort study published in 2014 found that vasopressor usage was associated with increased complications in patients with spinal cord injury, with dopamine and phenylephrine being the most commonly used vasopressors 6.
• In the context of emergency department evaluation and management, hypotension can be a sign of significant underlying pathology, and treatment should be targeted at the underlying etiology, with expedited bedside evaluation and rapid initiation of treatment being paramount 7.

Pressor Usage and Complications

• The use of pressors in traumatic hypotension is associated with various complications, including cardiogenic complications, ventricular tachycardia, troponin elevation, atrial fibrillation, and heart rate abnormalities 3, 6.
• Dopamine and phenylephrine are the most commonly used vasopressors in this context, with dopamine being associated with a higher risk of complications in patients over 55 years old 3.
• Norepinephrine may be a safer alternative to dopamine and phenylephrine, with studies suggesting that it promotes better restoration of blood flow and oxygenation to the traumatically injured spinal cord 4, 5.

Clinical Implications

• The use of pressors in traumatic hypotension should be carefully considered, with attention to the potential risks and benefits of different vasopressors 3, 4, 5, 6.
• Further prospective studies are needed to determine the optimal mean arterial pressure goals and vasopressor administration strategies for patients with traumatic hypotension and spinal cord injury 3, 4, 6.