The crashing patient: hemodynamic collapse

Abstract

Purpose of review: Rapid restoration of tissue perfusion and oxygenation are the main goals in the resuscitation of a patient with circulatory collapse. This review will focus on providing an evidence based framework of the technological and conceptual advances in the evaluation and management of the patient with cardiovascular collapse.

Recent findings: The initial approach to the patient in cardiovascular collapse continues to be based on the Ventilate-Infuse-Pump rule. Point of care ultrasound is the preferred modality for the initial evaluation of undifferentiated shock, providing information to narrow the differential diagnosis, to assess fluid responsiveness and to evaluate the response to therapy. After the initial phase of resuscitative fluid administration, which focuses on re-establishing a mean arterial pressure to 65 mmHg, the use of dynamic parameters to assess preload responsiveness such as the passive leg raise test, stroke volume variation, pulse pressure variation and collapsibility of the inferior vena cava in mechanically ventilated patients is recommended.

Summary: The crashing patient remains a clinical challenge. Using an integrated approach with bedside ultrasound, dynamic parameters for the evaluation of fluid responsiveness and surrogates of evaluation of tissue perfusion have made the assessment of the patient in shock faster, safer and more physiologic.

Figure 1

The concept of preload responsiveness represented on the cardiac function curve describing the Frank–Starling law of the heart. The increment in enddiastolic volume or preload by administration of a bolus of fluid will result in a significant increase in stroke volume (* on Y axis) and cardiac output only if the ventricular function is in the steep portion of the Frank–Starling curve of the heart (gray, thick line). The magnitude of the increase in cardiac output that is considered significant is most frequently set between 10 and 15%. Conversely, a bolus of fluid (same volume), which expands the end-diastolic volume in the same proportion as the previous example, will not result in an increment of more than 10–15% (# on Y axis) of the cardiac output if the ventricle is operating in the flat portion of the Frank–Starling curve (black, thick line).