WASHINGTON, D.C.—Managing the patient in cardiogenic shock can be daunting, according to Peter M. DeBlieux, MD, FACEP, director of resident and faculty development, emergency medicine at the Louisiana State University School of Medicine in New Orleans. Part of the issue is the lack of definitive information central venous pressure measurements provide. Data show that pulse pressure variation (PPV) measurements coupled with point-of-care ultrasound can provide much more relevant and accurate data in determining the best course of emergency care. In several studies, adding limited point-of-care echocardiography to standard care procedures produced better outcomes in undifferentiated vasopressor dependent shock.
Managing cardiogenic shock is directed toward identifying defects with the tank (depleted fluid status), the pump (poor ejection fraction), and/or the hose (inadequate peripheral systemic resistance). Ideally, problem areas should be addressed simultaneously.
Measuring PPV via an arterial line or noninvasive arterial pressure monitoring and recording a 15 percent change blood pressure during the respiratory cycle is a sign of volume depletion. Similarly, passively raising the legs and recording a change of 12–15 percent in systolic blood pressure is an indication of fluid responsiveness. In the presence of preserved LV fraction, serial boluses of 250 mL crystalloid fluid every 15 minutes are indicated in these situations.
Dr. DeBlieux recommends ordering a vasopressor (norepinephrine) and an inotrope (dobutamine) to the patient’s bedside early. They are inexpensive and infusions can begin as soon as the condition of the heart can be determined. It is safe to administer vasopressors through peripheral intravenous access. Retrospective studies have shown low rates of extrasavation and sequelae.
Point-of-care ultrasound can rapidly differentiate between massive pulmonary embolism, right heart failure, pericardial effusion, and sepsis due to community-acquired pneumonia, all of which can result in elevated troponin and B-type natriuretic peptide. If ejection fraction (EF) is reduced, begin treatment with an inotrope such as dobutamine, avoiding more cardiotonic vasopressors such as epinephrine or dopamine. If EF is preserved, administer a serial bolus of crystalloid fluid and blood transfusion. If systemic vascular resistance is low, norepinephrine is administered until mean arterial blood pressure rises to above 65 mmHg. Norepinephrine can be added to dobutamine for persistent hypotension in the setting of reduced EF.
Positive pressure ventilation also has benefit in the setting of elevated preload and reduced EF. Reducing preload enhances EF in acute decompensated congestive heart failure. The use of noninvasive airway procedures such as bag-valve mask, humidified high-flow nasal cannula, and bi-level positive airway pressure are recommended, as the chances of crashing the hypotensive patient with intubation is higher than in other critically ill patients. Dr. DeBlieux recommends that if the patient’s situation will improve over the next 15 minutes during care, then resuscitate first. If not, then rapid sequence intubation is indicated.