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

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

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

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

We don’t want action after distress Pain nurse dilutes prepares drug Analgesia Blood absor IM conc. PCAPCA

MEAC

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

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

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

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

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

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

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

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

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

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

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

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 ??

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

Lock out ?? Brain to blood Blood to brain Redistribution

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

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

Total dose 1 hour 4 hours

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

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

Morphine - ? Renal insuffiency Bilirubin Preeclampsia Smooth muscle spasm

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

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

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

Side effects Operator error Patient error Equipment malfunction

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

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

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

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

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

Other methods - PCEA loading – basal – demand- lock out Morph Peth Fentanyl

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

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

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

To understand PCA USE it Make it available in your institutes

Thank you all