What are the causes and management of post-cardiac arrest hypotension?

From the Guidelines

Post cardiac arrest hypotension should be treated promptly with a target mean arterial pressure (MAP) of at least 65 mmHg to ensure adequate organ perfusion, as supported by the most recent guidelines 1. Begin with an initial fluid bolus of 1-2 L of crystalloids (normal saline or lactated Ringer's) to address potential hypovolemia. If hypotension persists after fluid resuscitation, start vasopressors, with norepinephrine as the first-line agent at 0.1-0.5 mcg/kg/min, titrated to achieve the target MAP, as recommended by recent studies 1. Alternatively, epinephrine (0.05-0.5 mcg/kg/min) or vasopressin (0.01-0.04 units/min) can be used. Dobutamine (2-20 mcg/kg/min) may be added for patients with reduced cardiac contractility. Some key points to consider in the management of post cardiac arrest hypotension include:

• Continuous cardiac monitoring, frequent blood pressure checks, and assessment of tissue perfusion are essential.
• The underlying cause of hypotension should be identified and addressed, which may include myocardial stunning, systemic inflammatory response, or ongoing bleeding.
• Echocardiography can help evaluate cardiac function and guide therapy.
• Hypotension after cardiac arrest is associated with worse neurological outcomes, as the post-arrest brain is particularly vulnerable to hypoperfusion, making prompt and effective blood pressure management crucial for improving survival and neurological recovery, as highlighted in recent guidelines 1. It is also important to note that the optimal strategy to achieve a BP above the threshold level, and whether a BP target or another marker of end organ perfusion is the most appropriate target, are still areas of ongoing research and debate 1. However, based on the most recent and highest quality evidence, the use of norepinephrine as the first-line vasopressor, with a target MAP of at least 65 mmHg, is the recommended approach for managing post cardiac arrest hypotension 1.

From the FDA Drug Label

To maintain systemic blood pressure during the management of cardiac arrest, LEVOPHED is used in the same manner as described under Restoration of Blood Pressure in Acute Hypotensive States. After observing the response to an initial dose of 2 mL to 3 mL (from 8 mcg to 12 mcg of base) per minute, adjust the rate of flow to establish and maintain a low normal blood pressure (usually 80 mm Hg to 100 mm Hg systolic) sufficient to maintain the circulation to vital organs

The treatment for post cardiac arrest hypotension involves administering norepinephrine (IV) to maintain a low normal blood pressure (usually 80 mm Hg to 100 mm Hg systolic) sufficient to maintain the circulation to vital organs 2.

• The initial dose is 2 mL to 3 mL (from 8 mcg to 12 mcg of base) per minute.
• The rate of flow should be adjusted based on the patient's response.
• The average maintenance dose ranges from 0.5 mL to 1 mL per minute (from 2 mcg to 4 mcg of base) 2.
• High dosage may be necessary in some cases, but occult blood volume depletion should always be suspected and corrected when present 2.

From the Research

Post Cardiac Arrest Hypotension

• Post cardiac arrest hypotension is a critical condition that requires immediate attention and management.
• According to 3, current guidelines recommend targeting a mean arterial pressure (MAP) of higher than 65-70 mmHg using fluid resuscitation and the use of vasopressors.
• The management strategies for post cardiac arrest hypotension may vary based on the setting, such as pre-hospital versus in-hospital phase.
• Epidemiological data suggest that some degree of hypotension requiring vasopressors occurs in almost 50% of patients, as stated in 3.

Blood Pressure Targets

• The optimal blood pressure target for post cardiac arrest patients is still a topic of debate.
• A higher MAP could theoretically increase coronary blood flow, but on the other hand, the use of vasopressors may result in an increase in cardiac oxygen demand and arrhythmia, as mentioned in 3.
• An adequate MAP is paramount for maintaining cerebral blood flow, and in some cardiac arrest patients, the cerebral autoregulation may be disturbed, resulting in the need for higher MAP to avoid decreasing cerebral blood flow.

Fluid Resuscitation

• The choice of fluid for resuscitation in post cardiac arrest hypotension is also important.
• Studies such as 4 and 5 compared the use of lactated Ringer's solution and normal saline for initial fluid resuscitation in critically ill patients, including those with sepsis-induced hypotension.
• The results of these studies suggest that lactated Ringer's solution may be associated with improved survival and outcomes compared to normal saline.

Predictors of Mortality

• Lactate levels and the need for vasopressors after in-hospital cardiac arrest have been identified as predictors of mortality, as stated in 6.
• Elevated lactate levels and the need for vasopressors within 3 hours after return of spontaneous circulation (ROSC) were associated with higher mortality rates.
• A multivariable model that includes lactate levels, age, body mass index, race, and history of arrhythmia, cancer, and/or liver disease may be helpful in stratifying mortality risk in patients requiring mechanical ventilation after in-hospital cardiac arrest.