Which antagonist (nondepolarizing) neuromuscular blocker is specifically used to treat multisystem organ failure?

Cisatracurium is the correct choice because it has unique pharmacokinetic properties that make it particularly suitable for patients with organ failure, including those with multisystem organ failure. Unlike some other nondepolarizing neuromuscular blockers, cisatracurium undergoes a process called "spontaneous degradation" via a non-specific plasma enzyme pathway known as ester hydrolysis. This means that its metabolism is not significantly affected by liver or kidney function, which is critical in cases of organ failure where these organs may not be operating efficiently.

This characteristic allows for more predictable dosing and minimizes the risk of prolonged neuromuscular blockade, which can occur with other agents whose clearance is reliant on hepatic or renal function. Therefore, in a clinical setting where a patient is experiencing multisystem organ failure, cisatracurium is favored because it reduces the likelihood of accumulation and adverse effects, making it a safer option for neuromuscular blockade in these vulnerable patients.