Clinical indicators of systemic tissue hypoperfusion (‘shock’): A protocol for a systematic review and qualitative analysis of the literature

Review question / Objective: The objective of this review is to identify the current scientific evidence on the value of clinical signs to indicate systemic tissue hypoperfusion or shock. Condition being studied: In the literature and clinical studies, shock has traditionally been defined by a drop in arterial blood pressure under a critical threshold, e.g., a systolic blood pressure of 90 mmHg, a mean arterial blood pressure <65 mmHg or a relative drop in systolic blood pressure of ≥40 mmHg. From a pathophysiologic point of view, shock relates to an imbalance between tissue oxygen delivery as well as cellular oxygen consumption and utilization. In most cases, shock results from systemic tissue hypoperfusion with consequent decreased tissue oxygen delivery (commonly referred to as circulatory shock). Impaired cellular oxygen consumption and utilization appear to play contributory roles in specific disease states (e.g., sepsis) or conditions (e.g., intoxications).