Sources: Ian Holman, MD resident anaesthesiologist, Colorado State University, Anschutz Medical Campus, Aurora; David Dickerson, MD. But marijuana owners with heart or lung problems may be at risk in an operating room, depending on how much additional anesthesia they need during surgery, Holman added. During the operation, marijuana users need not only more inhaled sevoflurane anesthetics, but also higher doses of hydromorphic anesthetics, the researchers found. “Will there be changes in our neurophysiology or nervous system that will make us more excited, cause more pain after injury or during surgical recovery, or actually increase the amount of anesthesia that will make us sleep or deeper than sleep?” said Dickerson. Cannabis users who undergo surgery on a broken leg need higher doses of Sevoflurane, an inhaled anesthetic that would allow them to sleep during the surgery. Dickerson said there may be another unknown variable among people who choose to use cannabis, which requires higher levels of anesthesia, and what was found here is simply a connection without a direct causal link. In any case, Holman and Dickerson agree that more research is needed on the effect of marijuana on anesthesia. “Chronic alcoholics, who often did not drink alcohol before entering the operating room, also need a higher level of anesthesia,” Holman said. Marijuana can also change a person’s nervous system response to pain and painkillers, Dickerson said. Dr. Holman said the results are consistent with previous studies and indicate that patients using marijuana initially need more anesthesia to pass it. Marijuana users simply need to be honest with their doctors about the use of marijuana to be more accurate in choosing the dosage of anesthesia, Dickerson said. Using marijuana can change the way anesthesia and pain are treated in the body, Dickerson said. For this study, Holman and his colleagues reviewed data from 118 patients who had surgery at the University of Colorado Hospital for a shin fracture. Holman found that alcohol consumption clearly changes the amount of drugs a person needs. They also reported that after the surgery the pain level was higher and that higher doses of opiate analgesics were needed to suppress it.