However, problems can still arise. It is vital the dental staff are appropriately trained and qualified in dealing with complications and medical emergencies. Administering oxygen is of highest importance in an emergency situation. If patient is showing signs of oversedation, the concentration of nitrous oxide should be immediately reduced, and the oxygen concentration should be increased. All patients undergoing treatment under sedation should be continually assessed in the following: Respiratory rate Heart rate Oxygen saturation Colour of skin Level of consciousness Any deviation from the normal values should prompt the dental clinician to lighten the sedation.The dental clinician can recognise and deal with the following sedation related complications: Vasovagal attack (faint). It is more common in severely anxious patients and can be indicated by nausea and vomiting, pallor and a rapid pulse. Management of this patient involves lying patient supine, maintaining the airway and administering oxygen through a face mask. Airway obstruction. Sedation can hinder the patient's gag reflex. Therefore, patients can find it difficult to remove a foreign body lost in the mouth during dental treatment. If this occurs, the patient should be encouraged to cough. In more serious cases of airway obstruction, up to 5 back blows and abdominal thrusts should be given while the patient is leaning forward. Severe hypotension. Nitrous oxide causes a decrease in blood pressure due to a reduction in sympathetic function. However, significant hypotension may occur, if a patient sits up too quickly from the supine position or becomes oversedated, which can be potentially dangerous. To manage this complication, the dental treatment should be stopped. The patient should be laid back and basic life support initiated. Oxygen should be administered and the concentration of nitrous oxide reduced. Nausea and vomiting. This is an undesirable effect of sedation, rather than a secondary complication. It indicates the level of sedation is too high and the concentration of nitrous oxide should be reduced. There are some downsides relating to the use of nitrous oxide. It can present as a potential hazard to the operator in charge of administering the gas. It has been shown that continual exposure to nitrous oxide can result in illnesses, such as haematological disorders and reproductive problems. Thus, active or passive scavenging is essential to remove nitrous oxide from the environment. Another disadvantage can be the risk of mouth breathing. Inhalation sedation requires the patient to breath through the nose, which can