Intrathecal Fentanyl

Fentanyl and sufentanil are far more lipid soluble than morphine. thus the risk of delayed respiratory depression from rostral spread of intraspinally administered narcotic to respiratory centers is greatly reduced (Tucker, AP., Mezzatesta, J., Nadeson, R., and Goodchild, CS., 2004).
Remifentanil was developed in an effort to create an analgesic with a more rapid onset and predictable termination of effect. The potency of remifentanil is approximately equal to that of fentanyl. The pharmacological properties of remifentanil are similar to those of fentanyl and sufentanil (Ross AK, Davis PJ, Dear GL, et al., 2001). They have similar incidences of nausea, vomiting, and dose-dependent muscle rigidity. Nausea, vomiting, itching, and headaches have been reported when remifentanil has been used for conscious analgesia for painful procedures (Egan TD., 2000). Intracranial pressure changes are minimal when ventilation is controlled. Seizures after remifentanil administration have been reported. Remifentanil has a more rapid onset of analgesic action than fentanyl or sufentanil (Saravanakumar K, Garstang JS, Hasan K., 2007). Analgesic effects occur within 1 to 1.5 minutes. Remifentanil is unique in that it is metabolized by plasma esterases. Elimination is independent of hepatic metabolism or renal excretion, and the elimination half-life is 8 to 20 minutes (Owen MD, Poss MJ, Dean LS, et al., 2002). There is no prolongation of effect with repeated dosing or prolonged infusion (Olufolabi AJ, Booth JV, Wakeling HG, et al., 2000). Age and weight can affect clearance of remifentanil, requiring that dosage be reduced in the elderly and based on lean body mass. Remifentanil hydrochloride is useful for short, painful procedures that require intense analgesia and blunting of stress responses (Volmanen P, Akural EI, Raudaskoski T, et al., 2002). The titratability of remifentanil and its consistent, rapid offset make it ideally suited for short surgical procedures where rapid recovery is desirable. Remifentanil also has been used successfully for longer neurosurgical procedures, where rapid emergence from anesthesia is important (Blair JM, Hill DA, Fee JP., 2001). However, in cases where postprocedural analgesia is required, remifentanil alone is a poor choice (Babenco HD, Conard PF, Gross JB., 2000).
Fournier and co-workers in their study published in Anesthesia Analgesia compare the postoperative analgesic effects of intrathecal fentanyl and sufentanyl with the set end points being the parameters of onset, quality, and duration of action. The authors undertake a detailed literature review, where the reader understands the perspectives and aim of this study in a clear manner. Intrathecal opioid analgesia with lipophilic opioids is a well accepted anesthetic procedure for postoperative and labour pain (Cowan, CM, Kendall, JB., Barclay, PM., and Wilkes, RG., 2002). Drugs like sufentanil and fentanyl are widely used for pain relief during labor, and they have predictable onset and end points of action. However, these drugs are not often used for postoperative analgesia (Meininger, D. et al., 2003). This study has investigated the use of continuous spinal anesthesia as the mode of