Vasoconstrictors in Spinal Anesthesia with Tetracaine???A Comparison of Epinephrine and Phenylephrine

Mechanisms for the Anti-nociceptive Actions of the Descending Noradrenergic and Serotonergic Systems in the Spinal Cord

“…Adrenaline is widely used clinically for spinal anesthesia with local anesthetics with an expectation of a reduction in the clearance of local anesthetics from the subarachnoid space by the constriction of blood vessels (46,47). However, adrenaline produces analgesia when administered intrathecally in the absence of local anesthetics (48,49); in fact, they do not significantly alter the clearance of local anesthetics from the subarachnoid space (50,51) In addition, clonidine, an α 2 agonist without vasoconstrictive effects, prolongs the duration of analgesia (52).…”

Addition of epinephrine to intrathecal tetracaine augments depression of the bispectral index during intraoperative propofol sedation

“…Although epinephrine has been employed for many years, few clinical studies have been conducted to investigate its effect on sedation. Epinephrine produces vasoconstriction, potentially decreasing vascular absorption of the local anesthetic and increasing the concentration of local anesthetic in the spinal cord, and epinephrine also stimulates the α2-adrenoceptor in the descending pathways of the spinal cord, which inhibits the transmission of pain signals [4][5][6][7]. Possibly through these mechanisms, epinephrine improves the quality of subarachnoid block.…”

“…BIS has been shown to be simple and sensitive for assessing the level of consciousness during propofol sedation [13][14][15]. We determined the amount of epinephrine and propofol from past studies [4][5][6][7].…”

“…Tverskoy et al [2] reported that subarachnoid blockade decreased the hypnotic requirements of sedative drugs. Epinephrine has been added to local anesthetic agents used for spinal anesthesia to prolong the duration of anesthesia [4][5][6][7]. Epinephrine stimulates α-adrenoceptors in the decending pathways of the spinal cord, which then inhibit the transmission of pain signals [8,9], and it is known that α2-adrenoceptor agonists have a central inhibitory effect [10][11][12].…”

Neuraxial Blocks: Spinal and Epidural Anesthesia

“…However, the signifi cant prolongation is observed when vasoconstrictors are added to tetracaine, when compared with their use along with lignocaine or bupivacaine [ 127 ]. The recommended dose range of intrathecal epinephrine is 0.2-0.3 mg and that of phenylephrine is 2-5 mg. Due to delay in return of sacral autonomic function causing delay in the ability to void and increased risk of urinary retention, the use of vasoconstrictors is not recommended in ambulatory surgery [ 111 ].…”