The journal Anesthesia & Analgesia has announced the retraction of 22 papers by German Joachim Boldt on results of medical studies for which he had not obtained the required ethical approval.

The former chief anaesthesiologist of the Ludwighafen Hospital claimed to have developed a safe and effective method for anesthetising patients that keeps their blood circulating during surgery. The Medical Board of the state of Rheinland-Pfalz, which last month concluded an investigation into Boldt’s practices, found that he had conducted most studies involving patients without the necessary approval by an ethics committee.

According to the International Anesthesia Research Society a total of 89 papers could be affected, including the 22 papers Boldt published between 1999 and 2009 in Anesthesia & Analgesia.

“The serial misconduct of Joachim Boldt will result in a staggering number of retractions for lack of [ethical] approval,” the journals’ editors write in the current issue.

Meanwhile, a separate investigation in is ongoing at the Ludwigshafe Hospital on whether Boldt has also fabricated data for his studies. Boldt was dismissed from his post last November.