Background: anesthesia and sedation are an essential part of surgical operations and treatment in the intensive care unit. Sedation in the ICU is essential to keep patients well while they are intubated, mechanically ventilated, or agitated. It is also a cornerstone when they undergo any kind of invasive procedures. Most patients who require anesthesia are in generally bad health condition, such as failed kidney or liver, putting them at a greater danger of the complication of anesthesia itself. Newer agents, however, are trying to overcome these challenges. Aim of the Work: our aim in this study is to understand the mechanism of action of inhaled anesthesia, study their common adverse effects and complication and explore how to prevent them. Material and Methods: we conducted this review using a comprehensive search of MEDLINE, PubMed, and EMBASE, January 1987, through March 2017. The following search terms were used: anesthesia, complication of anesthesia, inhaled anesthesia, overcoming challenges in surgery Conclusion: inhaled anesthetics are a basis in both surgical operations and sedation within the intensive care unit and are used for sedation or anesthesia. Most patients who require the use of anesthetics are critically ill, and may have renal dysfunction, hepatic dysfunction, or both. Therefore, the administration of safe anesthetic agent is essential to prevent the occurrence of severe adverse events. Newer agents have been reported to be safer.