The used of KALINOX® (50% nitrous oxide and oxygen) inhalation has demonstrated analgesic efficacy in various procedures (obstetric, liver biopsy, transrectal ultrasound guided prostate biopsy, emergency…) associated with mild to moderate pain and it is technically simple to use. Early studies indicated that 30% nitrous oxide is equipotent to 10 to 15 mg. morphine. Except in patients with severe chronic obstructive pulmonary disease KALINOX® inhalation is a safe and acceptable method of sedation and analgesia. It is a nonirritant and is excreted unchanged from the lungs.