Advanced Hemodynamic and Cardiopulmonary Ultrasound for Critically Ill Patients in the Emergency Department
Focused echocardiography, advanced hemodynamic, and cardiopulmonary point-of-care ultrasound studies provide time-sensitive evaluation of critically ill patients, guiding and facilitating earlier implementation of life-preserving treatment and supportive therapies.
Brachial Artery Peak Velocity Variation
In the search for easily accessible alternatives to cardiac and aortic flow, brachial artery peak velocity variation (BAPVV) was found to be useful for predicting volume responsiveness.75 To perform this study, the brachial artery is imaged in the long axis view using a linear transducer. Doppler gating should be adjusted to ensure an angle of less than 60°. The patient’s BAPVV is calculated as the difference between maximum and minimum peak velocity divided by the mean peak velocity. A variability in peak velocity of more than 10% predicts volume responsiveness.75
Common Carotid Artery Flow
Similarly, CCA flow has attracted attention as a potential surrogate to assess SV response to preload challenge.76,77 The CCA is large, easily accessible and does not require specialized training to assess (Figure 12).78
Even though cardiopulmonary interaction assessment has excellent performance for predicting volume responsiveness, limitations do exist. For example, cardiopulmonary interactions may be exaggerated or diminished—thus decreasing the reliability of this assessment—in patients on mechanical ventilation who have spontaneous breathing, high positive end-expiratory pressures or a high minute ventilation, low TV, dysrhythmias, external compression of extra- or intrathoracic vessels (eg, intra-abdominal hypertension, pericardial tamponade, COPD/asthma exacerbations); and in patients who have decreased arterial elastance, or high RV afterload causing RV dysfunction or failure.
Conclusion
The advanced ultrasound techniques described in this review provide several useful tools to rapidly evaluate and manage cardiopulmonary interactions and assess the hemodynamic profile of critically ill patients. With these bedside techniques added to basic POCUS examinations, a new era in noninvasive critical care management is now available.
As we enter the days of precision medicine, these examinations will enable EPs to optimize the care of this high-risk patient population. Moreover, future research by the emergency ultrasound and critical care communities on morbidity and mortality associated with resuscitation strategies in the ED will undoubtedly incorporate cardiopulmonary and hemodynamic ultrasound.
