How much alcohol do you drink? Do you smoke? Do you consume more drugs? When doctors ask such questions, it can be uncomfortable for patients. Nevertheless, they should not gloss over anything and necessarily answer honestly. For drug use can significantly affect the required dosage of anesthetics.
Anyone who smokes cannabis regularly, for example, has a significantly higher need for anesthetics, US researchers report in the journal "The Journal of the American Osteopathic Association". The anesthetic Propofol may require more than three times the dose of regular cannabis users.
"Cannabis has some metabolic effects that we do not understand," says study leader Mark Twardowski of Western Medical Associates, Grand Junction, Colorado. "Patients need to know that their cannabis use may make other medicines less effective."
220 percent more propofol
For the analysis, the researchers randomly selected 250 patients who had to undergo gastroscopy between 2016 and 2017. One in ten said they regularly consume cannabis. The doctors each compared the amount of anesthetic used with the information provided by the patients on their drug use. In addition to cannabis products, the use of alcohol, opiates and benzodiazepines was also queried. The latter occur, for example, in psychotropic drugs.
The extent to which cannabis use had an effect on the dosage varied according to the anesthetic used. Fentanyl accounted for nearly 14 percent, midazolam more than 20 percent, and 220 percent propofol. Some even required more than a three-fold dose of propofol.
Although the number of study participants is not representative and relatively small, the study confirms previous analyzes. Therefore, the result is not surprising, says Götz Geldner, Medical Director of the Department of Anaesthesiology, Intensive Care Medicine, Emergency Medicine and Pain Management at the Hospital in Ludwigsburg, who was not involved in the study.
Drugs enhance detoxification function of life
The fact that patients taking psychoactive substances such as alcohol need more anesthetics has long been known among anesthesiologists. "If the liver often gets involved with cannabinoids or alcohol, it enhances its detoxification function," says Geldner. As a result, anesthetics would break down faster. In addition to drugs and alcohol, tranquilizers and other psychotropic drugs influence the effectiveness of anesthetics.
In a patient questionnaire recommended by the German Society for Anaesthesiology and Intensive Care Medicine, the question of drug use has been asked for about ten years. According to Geldner, more than 90 percent of German hospitals use a comparable questionnaire. However, this requires that patients respond honestly. Only with a blood test can physicians determine with absolute certainty how high the drug really is.