United States General Anaesthetic Drug Market Report, by Drugs (Isoflurane, Desflurane, Sevoflurane, Ketamine, Thiopental, Opioids, Propofol), Route of Administration (Intravenous Anaesthetic, Inhaled Anaesthetic), End User (Hospitals, Speciality Clinics, Ambulatory Surgical Centres)- United States Market Share, Trend, Analysis & Forecast