While doctors know how hiccups work, they don't really know why hiccups happen. The way they work is your diaphragm -- the muscle between your abdomen and chest used for breathing -- suffers a sudden spasm. Then you gasp, and the glottis shuts your vocal cords and traps the air there. The noise of the shutting vocal cords is the hiccup.
Some hiccup triggers have been identified, and anesthesia is one of them. However, hiccups caused by anesthesia are usually of the chronic type. Hiccups can be short-term and last just a few minutes or hours. They go away on their own or via one of the home remedies people like to try, like holding your breath. However, hiccups that last more than 48 hours are called persistent hiccups, and those that last longer than a month are said to be intractable. Anesthesia, along with central nervous system problems and metabolic problems, can cause long-term hiccups.