General Anaesthesia - Preanaesthetic Evaluation

Preanaesthetic Evaluation

Prior to planned operation or procedure, the anaesthetist reviews the medical record and/or interviews the patient to determine the best combination of drugs and dosages and the degree to which monitoring will be required to ensure a safe and effective procedure. Key factors of this evaluation are the patient's age, body mass index, medical and surgical history, current medications, and fasting time. Thorough and accurate answering of the questions is important so that the anaesthetist can select the proper anaesthetic drugs and procedures. For example, a patient who consumes significant quantities of alcohol or illicit drugs could be undermedicated if s/he fails to disclose this fact. This in turn could then lead to anaesthesia awareness or dangerously high blood pressure. Commonly used medications (e.g., sildenafil) can interact with anaesthesia drugs; failure to disclose such usage can also increase the risk to the patient. There are some situations (where patients are on a certain medication and must undergo a given procedure) in which local anaesthesia or regional anaesthesia can be given, but instead general anaesthesia is chosen, though this is not extremely common due to the fact that general anaesthesia is by nature more dangerous and the agents used react with many more medications.

An important aspect of the preanaesthetic evaluation is that of the patient's airway, involving inspection of the mouth opening and visualisation of the soft tissues of the pharynx. The condition of teeth and location of dental crowns and caps are checked, neck flexibility and head extension observed. If a tracheal tube is indicated and airway management is deemed difficult, then alternative methods of tracheal intubation, such as fibreoptic intubation, may be required as part of the anaesthetic management.