GP-Palliative Care Forum held on 16 November 2016
KEY LEARNING POINTS
BY DR M JOSEPH MBBS FRCP
TOPIC: MANAGING PAIN IN THE DYING STAGE
- In agonising pain in terminal cancer, absolute pain control takes precedence over undue concerns with regard to sedation. Nevertheless, the aim is to control pain adequately with minimal sedation as far as possible.
- In severe, complex pain particularly from cancer, there often exists a predominant neuropathic pain component. In this situation, the clinician should guard against inadvertent, opioid dose escalation, which has the potential to aggravate pain by the phenomenon of ‘opioid induced hyper-algesia’. This phenomenon is particularly significant with pure mu opioid agonists such as Morphine, Fentanyl in high doses.
- Once a predominant neuropathic pain component is identified, in addition to the opioid, co-analgesic adjuvants should be utilised in order to prevent opioid dose escalation, improve pain and reduce sedation.
- We have now recently realised the real analgesic benefit of using Phenobarbital in a separate, additional CSCI (continuous sub-cutaneous infusion) at a starting dose of 400mg/24 hours in patients with agonising pain in the dying stage, despite the use of an opioid (example, Diamorphine) , Benzodiazpine (Midazolam, anti-convulsant dose) and Phenothiazine (Levomepromazine, adequate dose) in a CSCI.
- Crucial pharmacological analysis of Phenobarbital revealed that it possess anti- Glutaminergic effect, anti-AMPA effect and Gaba-ergic effect which make it well suited for managing severe neuropathic pain. Of course, in addition, being a Barbiturate, it will provide a beneficial tranquilising effect in the dying stage much to the comfort of the relatives in their recollection during the bereavement process.