title: The effect of intravenous morphine on the level of spinal anesthesia with lidocaine.
abstract: One of the major concerns in spinal anesthesia with lidocaine is its short duration of action. Enhancement is necessary in some situations during surgery, because surgeons encounter with unexpected events and need more time. Therefore there is a need to increase anesthesia duration in these situations. Many studies investigated various additives with different administration routes to enhance spread and duration of spinal block with lidocaine. Because we only have morphine sulfate in our clinics and the sulfate compounds are neurotoxic, we cannot prescribe it by intrathecal route; for this reason we investigated effects of intravenous morphine on the spinal anesthesia with lidocaine.
  
  
  METHODS
  This double blinded randomized clinical trial study was performed on 36 patients who were allocated to two groups. All patients underwent spinal anesthesia with lidocaine by the same method. Patients in the case group received morphine plus midazolam intravenously as the additive medication and in the control group received normal saline plus midazolam. Duration, spinal block level, recovery time, sedation score and adverse effects were compared between the two groups.
  
  
  RESULTS
  This study showed that although intravenous morphine can provide better safe sedation (p-value < 0.01), it has no effect on the level (p-value: 0.42) and duration of spinal block (p-value: 0.26). Although heart rate and blood pressure had significant decrease in the case group (p-value < 0.01 and < 0.05 respectively) but the need for administration of ephedrine was completely similar in both groups.
  
  
  CONCLUSIONS
  Although some studies had proved the efficacy of systemic use of other opioids including fentanyl and sufentanil, morphine had no effect on the level and duration of spinal block. It can be due to differences in the chemical structures of these substances. However, intravenous morphine as an additive to spinal anesthesia with lidocaine can provide acceptable sedation with no major side effects.
authors.affiliation: Department of Anesthesiology and Critical Care, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Masoudifar
authors.forename: Omid
authors.initials: O
authors.lastname: Aghadavoudi
authors.forename: Mehran
authors.initials: M
authors.lastname: Rezvani
authors.forename: Neda
authors.initials: N
authors.lastname: Mashayekhi
mesh_terms: D000759:Adjuvants, Anesthesia / Q000008:administration & dosage*; D000328:Adult; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000775:Anesthesia, Spinal; D000779:Anesthetics, Local / Q000008:administration & dosage*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008012:Lidocaine / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage*; D055815:Young Adult
chemical_list: D000759:Adjuvants, Anesthesia; D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D009020:Morphine; D008012:Lidocaine