Certified Surgical First Assistant (CSFA) Practice Test 2025 - Free CSFA Practice Questions and Study Guide

The earliest sign of malignant hyperthermia (MH) is an increase in end-tidal CO2. This is an important indicator because it reflects the metabolism within the muscles during an MH crisis. In malignant hyperthermia, there’s an uncontrolled release of calcium from the sarcoplasmic reticulum of skeletal muscle, leading to hypermetabolism. This hypermetabolism results in increased carbon dioxide production, which is detected as an elevation in end-tidal CO2.

Monitoring end-tidal CO2 concentrations is a critical aspect during anesthesia, as it can signal early changes in metabolic status before more severe signs of MH, like elevated body temperature or increased heart rate, become evident. Therefore, recognizing the increase in end-tidal CO2 allows for early intervention, which is essential in managing this potentially life-threatening condition.

While elevated body temperature and changes in heart rate are key symptoms of MH, they often occur later in the process as the condition progresses. Decreased urine output can result from metabolic changes and renal impairment due to severe hyperthermia, but it is not an early indicator of the condition itself. Thus, the increase in end-tidal CO2 stands out as the first measurable change signaling the onset of malignant hyperthermia.