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Intrathecal Narcotics for Post-operative Analgesia. Kristopher R Davignon, MD Dept of Anessthesia Grand Rounds March 2007. Intrathecal Narcotics. Opioids were know to the ancient Sumerians as of 4000 B.C. 1971 Opioid receptor discovered 1973 Receptors found in the brain
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Intrathecal Narcotics for Post-operative Analgesia Kristopher R Davignon, MD Dept of Anessthesia Grand Rounds March 2007
Intrathecal Narcotics • Opioids were know to the ancient Sumerians as of 4000 B.C. • 1971 Opioid receptor discovered • 1973 Receptors found in the brain • 1976 Receptors found in the spinal cord • 1979 Early reports of intrathecal opioids producing analgesia
Intrathecal Narcotics • Thoracic and Upper Abdominal Procedures • Elective Total Hip Arthroplasty • 350,000 Procedures per year in the US • + 5 min to consent • + 15 min for procedure
Overview and Goals • Anatomy, Physiology & Pharmacology • Complications • Evidence Based Practice • Dose-Response • Future Directions
Anatomy, Physiology & Pharmacology • Drug disposition depends primarily on lipid solubility • Any drug rapidly redistributes • opioid is detectable in the cisterna magna within 30 min of lumbar intrathecal administration
Opiods Morphine Meperidine Hydromorphone Sufentanil & Fentanyl Methadone Non Opiods Clonidine Neostigmine Adenosine Epinephrine Ketorolac Midazolam Anatomy, Physiology & Pharmacology Preservative
Anatomy, Physiology & Pharmacology • Lipophilic opioids • Rapidly traverse the dura; sequestered in epidural fat (and enter systemic circulation) • Rapidly penetrate the spinal cord and bind receptors and nonspecific sites
Anatomy, Physiology & Pharmacology • Hydrophilic opiods • Limited binding to epidural fat and nonspecific receptors • Slower transfer to systemic circulation • Higher CSF concentrations accounting for rostral spread
“Complications” • Pruritus • Mechanism unclear – likely opiod receptor mediated (not histamine) • Incidence 30-100% • Rx: Antihistamines, 5-HT3 antagonist, opiod antagonists (or agonist-antagonists), propofol
“Complications” • Urinary Retention • Not dose dependent • Can last 14-16 hours • Most frequent with Morphine • 35 % incidence • Mechanism related to sacral parasympathetic outflow inhibition • Allows increase in maximal bladder capacity
“Complications” • Nausea and Vomiting • Incidence 30 % • Most profound with Morphine • Likely due to cephalad migration of drug to area postrema
“Complications” • Respiratory Depression • Incidence is dose dependent • Very Rare 0.09% to 0.4% • Likely no more clinically relevant than for IV narcotics • Monitoring for 18-24 hours when using lipophilic opiods
“Complications” • PDPH • Age, Gender, History of PDPH, Obesity • Multiple dural puncture, Needle size, Needle design
“Complications” • PDPH • Rx: • hydration • Caffeine • Sumatriptan • ACTH • EBP
“Complications” • Neuropraxia/Paralysis • Epidural hematoma • Epidural abcess
Evidence Based Practice • What types of surgery is amenable to intrathecal narcotics? • What doses should we use? • What outcomes can we affect?
Types of Surgery • Thoracic • Including Cardiac • Intra-abdominal • Including C/S, AAA, Open Cholecystectomy • Lower Extremity • Including THA & TKA
Narcotic Only (worst) • Narcotic + LA (best) • LA Only
“the Dose” • 1) Optimal dose depends on the surgical procedure • 2) Incidence of side effects increases in proportion to dose (especially with doses > 300 ųg)
Dosing for THA • Use lowest dose possible! • Studies have used doses as low as 0.025 mg • Older studies used doses as high as 0.5mg • Ideal dose seems to be 0.1 mg • Lower doses don’t provide good analgesia • Higher doses plagued with pruritis
Future Directions • Anticoagulants • Use of stents and anti-platelet agents • Aggressive DVT prophlaxis • Absence of laboratory evidence of these agents • Sustained release neuraxial narcotic • Depodur
Future Directions • Depodur (morphine sulfate extended release liposome injection)
Future Directions • Better Pain Scores for 48 hours • Studied in Hip Arthroplasty, Cesarean Section, Lower Abdominal Surgery • No significant difference in side effects from IV narcotic
Conclusions • Pain management in the in-patient setting is becoming a priority for adminstrative organizations • A majority of in-patient pain management is post-operative • Neuraxial narcotics consistently reduce patient’s VAS