Pain facts 7

1. Pain facts 7 Dr. S. Parthasarathy MD., DA., DNB, MD (Acu), Dip. Diab. DCA, Dip. Software statistics PhD (physio) Mahatma Gandhi medical college and research institute , puducherry – India

2. Patient controlled analgesia • The patient controls his own analgesia • the use of a sophisticated microprocessor-controlled infusion pump that delivers a preprogrammed dose of opioid when the patient pushes a demand button

3. Patient controlled analgesia • Any analgesic given by any route of delivery (i.e., oral, subcutaneous, epidural, peripheral nerve catheter) can be considered PCA if administered on immediate patient demand in sufficient quantities. • But routine is IV opioids

4. Background • The traditional approach of IM opioids given pro re nata (prn) results in at least 50% of patients experiencing inadequate pain relief after surgery. • Sechzer - the true pioneer of PCA evaluated the analgesic response to small IV doses of opioid given on patient demand by a nurse in 1968 and then by machine in 1971

5. We don’t want action after distress • Painnursedilutes prepares drug Analgesia Blood absor IM conc. PCA

7. MEAC

8. Indications • Acute post op pain • Trauma • Cancer • Labour • Burns • Sickle cell crisis • Sedation

9. Advantages • Better analgesia with same sedation • Better pulmonary results and less complications • Length of hospital stay • POCD is less • Patient satisfaction

10. Relative contraindications • Sepsis • Fluid electrolyte disturbance • Hepatic or renal disease ( severe disease ) • Sleep apnoea • Severe COPD

11. PCA system • Programmable electronic devices • Flexibility , • Display and memory, cost • Disposable fixed programme devices • Nonweight , hydrostatic pressure based • No alarms, rudimentary but cheap

12. How to use • Methods • Demand dose , • DD + basal infusion , • DD + tail • Adjustable infusions

13. Variables • Loading dose • Demand dose • Lock out interval • Basal infusion • 1 or 4 hourly maximum • Variables + drug = prescription

14. Loading dose • We should understand that PCA is a maintenance therapy • It needs loading dose.

15. Loading dose • HIGH LOADING DOSE • OPIOID BASED ANAESTHESIA • Correlated with less analgesic requirements • Morphine – 3 -5 fentanyl 50 mic • Pethidine – 25 tramadol 100

16. Basal infusion • Less fluctuation ,increased pt. satisfaction • Sleep more medication • Per hour doses • Morphine – 1 fentanyl 10 mic • Pethidine – 25 tramadol 12

17. Demand dose • The amount of drug injected as soon as the patient presses the button • Burp or tweek sound • dose is too small, they stop making demands • become frustrated with PCA, resulting in poor pain relief • Upto 5-6 doses / hour

18. Demand dose • Demand dose is too large, plasma drug concentration may eventually reach toxic levels- side effects ensue • Optimal dose • Morphine - 1 mg • Pethidine – 10 mg • Fentanyl – 10 mic

19. Lock out interval • Patient cant go on to press 10 times in half hour – get toxic doses • The time delay before the patient cannot go to the next dose • Onset of action of the drug • Fentanyl and morphine • Relative onset and duration ??

20. Classical times • Morphine – 8 min • Pethidine – 8 min • Fentanyl - 6 minutes • Short dose and lock out • Large dose and lock out • Fentanyl -- ?

21. Lock out ?? • Brain to blood • Blood to brain • Redistribution

22. Demand dose or lock out • Attempts • Sound • May deliver or not • Adjusted infusion

23. Nothing like this • One size fits all • Set and forget • The doses are only approximate Patient weight prevents toxicity but efficacy ?

24. Total dose • 1 hour • 4 hours

25. Assumptions • Side effects are produced at higher brain concentrations than the analgesic effect • Pain intensities are rarely constant • Pain relief is ideal in MEAC only

26. Ideal opioid • Rapid onset • Medium duration • Less side effects • No ceiling to analgesia • Morphine -- pethidine – fentanyl

27. Morphine - ? • Renal insuffiency • Bilirubin • Preeclampsia • Smooth muscle spasm

28. Pethidine • Seizures • Sickle cell crisis nor meperidine increased • Papillary necrosis in renal dysfunction

29. Fentanyl • Ideal for renal and hepatic dysfunction cases • But short duration should be in mind • Other drugs – hydromorphone, pentazocine and buprenorphine are used

30. Monitoring • Staff • ABG • Respiration • Sedation score • But pulse oximetry is accepted as the monitor for PCA

31. Side effects • Operator error • Patient error • Equipment malfunction

32. Side effects of opioids • Nausea and vomiting • No difference • 30 % Vs 25% - PCA Vs IM • Use of anti emetics – similar

33. Respiratory depression • PCA is more – wrong • Lot of studies – 0.5 – 0.9 % Vs • Old age , COPD, equipment failure, concomitant opioid admin by other routes, wrong doses

34. Colonic pseudoobstruction • Abd, distension • Nausea • Vomiting, • Flatus • Yes but 6/154 in a study of PCA -- not threatening

35. Others • Sedation - 20 % • Dizziness - 13 % • Pruritus - 20 % • In a study with PCA with hydromorphone

36. PCA adjuncts • Promethazine – • Droperidol • Metoclopramide • TDS scopolomine • Naloxone • NSAIDs • Clonidine • Paracetomol • Nerve blocks

37. Other methods - PCEA loading – basal – demand- lock out • Morph. 2 0.5 0.2 30 • Peth. 30 10 10 20 • Fentanyl 50 30 10 15

38. Subcutaneous (clysis) • 0.2 mg Loading with 0.2 mg demand SC 15 min. lock out of hydromorphone • Obesity • Edema • Vasculitis • But if no proper IV access – OK

39. Rare routes • Intramuscular PCA • Paediatric PCA • Intraspinal PCA • Ventricular implantable PCA • Oral PCA • PCA with ketoroloc, midazolam has been done

40. Mr. X • Mr X bought a scooter • He did not know driving • He was struggling • One friend came near to say don’t worry, it will normalize in three months • Mr. X put the scooter into the shed to try it after three months

41. To understand PCA • USE it • Make it available in your institutes

42. Thank you all