Describing but not resolving several areas of ambiguity and conflicting authority in applying H&S Code 1799.110, this decision holds instead that a nurse anesthetist and trauma unit nurse lacked the specialized knowledge required to opine on the standard of care applicable to an intensive care unit neurosurgeon deciding whether a severe traumatic brain injury requires immediate surgical intervention, whether that standard of care was breached, or whether the delay caused the patient’s death. The nurse was the plaintiff’s only expert; hence, the trial court erred in denying the hospital summary judgment.