Sedation, (as opposed to general anaesthesia) creates hypnotic, sedative, anxiolytic, amnesic, anticonvulsant, and centrally produced muscle-relaxing properties. From the perspective of the person giving the sedation, the patient will appear sleepy, relaxed and forgetful, allowing unpleasant procedures to be more easily completed. Since there are little pain relief effects, sedatives (such as benzodiazepines) are often mixed with narcotics, or local anesthetics or both.

From the perspective of the person receiving sedative, the effect is to a state of general relaxation, forgetfulness and time passing quickly. Many drugs can produce a sedative effect including benzodiazepines, propofol, thiopental, ketamine and inhaled general anaesthetics. The advantage of sedation over a general anaesthetic is that it generally doesn't require support of the airway or breathing (no tracheal intubation or mechanical ventilation) and has less of an effect on the cardiovascular system which adds a greater margin of safety in some patients.

When pain is blocked using local anaesthetics from a part of the body, it is generally referred to as regional anaesthesia. There are many types of regional anaesthesia either by injecting into the tissue, infusing it through veins that feed the area or by blocking the nerves that supply sensation to the area. Nerve blocks are divided into peripheral or central nerve blocks.

When local anaesthetic is injected around a larger diameter nerve, that transmits sensation from an entire region, it is referred to as a nerve block. They are commonly used in dentistry, when the mandibular nerve is blocked for procedures on the lower teeth. With larger diameter nerves (such as the interscalene block for upper limbs or psoas compartment block for lower limbs) the nerve and position of the needle is localized with ultrasound or electrical stimulation. Using ultrasound, improves the speed of onset for the block and decreases the number of needle passes required. Because of the large amount of local anaesthetic required to affect the nerve, the maximum dose of local anaesthetic has to be considered. Nerve blocks are also used as a continuous infusion, following major surgery such as knee, hip and shoulder replacement surgery and are associated with improved outcomes. Nerve blocks are associated with a lower risk of neurologic complications when compared to neuraxial blocks.

Injecting local anaesthetic around the spinal cord is called central neuraxial anaesthesia and is used to provide analgesia in the abdomen, pelvis and lower extremities. It is divided into either spinal (injection into the subarachnoid space, epidural (injection outside of the subarachnoid space into the epidural space) and caudal (injection into the caudal/tail end of the spinal cord). Spinal and epidural are the most commonly used forms of central neuraxial blockade.

Spinal anaesthesia is a "one-shot" injection that provides rapid onset and profound sensory anaesthesia with lower doses of anaesthetic and is usually associated with neuromuscular blockade (loss of muscle control). Epidural anaesthesia uses larger doses of anaesthetic and through a catheter that is left in place during the procedure and can be topped-up. Epidural anaesthesia typically does not affect muscle control.

Because central neuraxial blockade causes arterial and vasodilation there is an expected drop in blood pressure. Since 75% of the blood volume is on the venous side of the circulatory system, so the effect on the venous vasculature largely dictates the degree of the drop. The physiologic affects are much greater when the block is placed about the 5th thoracic vertebrae. An ineffective block is usually due to inadequate anxiolysis or sedation rather than a failure of the block itself.