MEDICATIONS

Anesthesia techniques used in non-operating room anesthetizing locations range from no anesthesia, to sedation/analgesia, to general anesthesia. The choice of personnel to deliver the anesthesia care depends on the desired level of anesthesia, the patient's underlying medical condition, and the procedure to be performed. Medications used to provide sedation/analgesia result in a continuum of depth of sedation ranging from anxiolysis to general anesthesia.^[6] Sedation/analgesia is defined as the level of anesthesia in which patients are able to tolerate unpleasant procedures through relief of anxiety, discomfort, or pain and in which uncooperative patients are able to tolerate procedures requiring that they not move. Moderate sedation/analgesia is defined as the level of anesthesia in which the patient retains purposeful responses to stimulation, requires no airway intervention, and can maintain adequate ventilation and cardiovascular function. Nonanesthesia personnel may care for patients undergoing procedures that require minimal to moderate sedation/analgesia, provided that they are trained to rescue patients from deep sedation/analgesia. Deeper levels of sedation or general anesthesia or the presence of complex underlying patient conditions require the presence of adequately trained anesthesia personnel. Most procedures conducted in non-operating room anesthetizing locations can be performed under minimal to moderate sedation/analgesia.

Combinations of sedative and analgesic medications, such as benzodiazepines and opioids, provide effective moderate sedation (also see Chapter 68 ).^[6] It is recommended that the drugs be administered individually and the doses carefully titrated to achieve the desired effect in a given patient while recognizing that combinations of sedative and analgesic agents may cause more than additive respiratory depression. Patients receiving intravenous sedation/analgesia should have intravenous access maintained throughout the procedure. Otherwise, the need for intravenous access needs to be individually assessed according to the patient's condition, as well as the procedure planned. When oral agents are used (e.g., benzodiazepines, chloral hydrate), adequate time must be given to allow full drug uptake before supplementation can be considered. Repeat nonintravenous dosing of sedative/analgesics is specifically not recommended because of variability in drug absorption. Combinations of benzodiazepines (e.g., midazolam, diazepam) and opiates (e.g., fentanyl, sufentanil, morphine) have been the mainstay of intravenous sedation/analgesia. These agents are titratable, and antagonists are available: flumazenil for antagonism of benzodiazepine-induced sedation and naloxone for antagonism of opiate effects. These antagonists should be reserved for emergency use only because their administration can result in patient discomfort, as well as adverse side effects. The ASA has noted that the use of methohexital or propofol for analgesia/sedation can result in rapid onset of general anesthesia and that these agents are best reserved for the use of trained anesthesia personnel. Ketamine may alter the signs of anesthetic depth, as well as cause airway obstruction and pulmonary aspiration, and this agent should also be reserved for the use of anesthesia personnel.