Which of the following characterizes the washout phase of shock?

The washout phase of shock is characterized by systemic acidosis. During this phase, the body's ability to maintain homeostasis is compromised as tissue hypoperfusion leads to anaerobic metabolism. This results in an accumulation of lactic acid in the bloodstream, contributing to a decreased pH and creating a state of acidosis.

As shock progresses, cellular metabolism transitions from aerobic to anaerobic processes, which are less efficient and produce acidic byproducts. This shift can lead to a significant drop in systemic pH, resulting in systemic acidosis. Recognizing this phase is vital for healthcare providers, as it indicates an advanced level of shock that requires immediate medical intervention.

In contrast, metabolic alkalosis is less likely during shock because the body's compensatory mechanisms are typically exhausted. Increased heart rate often occurs as an early response to shock but does not define the washout phase. A decreased respiratory rate may be present, yet it can vary among patients; typically, respiratory efforts are increased as the body attempts to compensate for acidosis. Thus, systemic acidosis serves as the definitive characteristic of the washout phase of shock.