Cerebral Hemodynamic and Metabolic Responses to Anesthesia and Vasopressors in Adult Shoulder Surgery: A 2 × 2 Factorial Design Randomized Controlled Trial with Light-based Neuromonitoring (CHEM-FACT Study).

In 30 seconds

The CHEM-FACT study was a 2 × 2 factorial randomized controlled trial of 40 adults undergoing shoulder surgery in the beach chair position; 39 were analyzed. It compared propofol with sevoflurane and phenylephrine infusion with ephedrine boluses, measuring relative cerebral tissue oxygenation and oxygen metabolism during the first 30 min after positioning. Neither anesthetic nor vasopressor had a significant overall effect on average outcomes. Over time, phenylephrine was associated with a 9% greater decline in oxygenation and a 70% increase in relative cerebral metabolic rate compared with ephedrine.

Key findings

• Neither anesthetic nor vasopressor choice significantly affected average relative tissue oxygenation or cerebral oxygen metabolic rate during the 30-min observation period.
• Relative tissue oxygenation declined over time (β = -0.005 per minute; χ2 (1) = 10.2; P = 0.001), while relative cerebral metabolic rate increased (β = 3.2 per minute; χ2 (1) = 35.2; P < 0.001).
• Compared with ephedrine, phenylephrine was associated with a 9% greater oxygenation decline and a 70% increase in relative cerebral metabolic rate during 30 min.

Why it matters

The findings suggest that cerebral oxygenation and metabolic responses may evolve during beach-chair shoulder surgery, even when average values do not differ by anesthetic or vasopressor strategy. The observed time-dependent differences associated with phenylephrine highlight the value of considering trends, rather than only average measurements, when studying intraoperative cerebral physiology.

What to keep in mind

Only 39 patients were analyzed, and outcomes were assessed for the first 30 min after positioning using relative optical measures; the abstract does not report clinical neurologic outcomes.