Anesthesiology and Intensive Care

Anatomical Sites of Action General anaesthetic agents affect both brain and spinal cord to account for physiological responses to nociception, loss of consciousness and inhibition of explicit memory. Auditory and sensory evoked potential data implicate the thalamus as the most likely primary target, but secondary sites such as the limbic system (associated with memory) and certain cortical areas are also

    Etomidate is a hypnotic agent. It is a short-acting intravenous anaesthetic agent used for the induction of general anaesthesia and sedation. Of all of the available intravenous induction agents, etomidate consistently demonstrates the least direct myocardial depression in several in vitro models. Two well-designed studies using adult human atrial and ventricular tissue demonstrated no effect of etomidate on myocardial contractility in concentrations seen in clinical use.     Dosing . Initial: 0.2 to 0.6 mg/kg IV over 30-60 seconds for induction of anesthesia; maintenance: 5-20 mcg/kg/minute. Beneficial effects of etomidate are: rapid onset of action safe cardiovascular risk profile easy dosing profile slight suppression of ventilation lack of histamine liberation protection from myocardial and cerebral ischemia able to decrease intracranial pressure and maintain a normal arterial pressure in cases of traumatic brain inju...

Different clinical scenarios lend themselves to the use of certain induction agents when rapid sequence intubation (RSI) is needed. Head injury or stroke   —  In the patient with potentially elevated intracranial pressure (ICP) from head injury or stroke or other conditions, adequate cerebral perfusion pressure must be maintained to prevent secondary brain injury. This means avoiding elevations in ICP and maintaining adequate mean arterial pressure. For these reasons, etomidate or ketamine are used for induction of these patients. If the patient is hypertensive at the time of induction, etomidate is preferable, as it will not further elevate the blood pressure. In normotensive or hypotensive patients, either agent can be used. In the severely hypotensive patient, ketamine is preferable. Ketamine's analgesic effects minimize the adverse sympathetic stimulation of laryngoscopy, while etomidate lacks such effect. Pretreatment with a low do...