Analgesia: Word Breakdown Prefix “an-” means without Suffix “-algesia” means pain, sensitivity ANALGESIA: LACK OF SENSATIONS A deadening or absence of the sense of pain without the loss of consciousness.
Analgesics An analgesic (also known as a painkiller) is any member of the group of drugs used to relieve pain. The main pharmacological action of analgesics is on the cerebrum and medulla of the central nervoussystem.
Classes of Analgesics Paracetamol and NSAIDs The exact mechanism of action of paracetamol/acetaminophen is uncertain, but it appears to be acting centrally (in the brain rather than in nerve endings). Aspirin and the other non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenases, leading to a decrease in prostaglandin production. This reduces pain and also inflammation (in contrast to paracetamol and the opioids).
Classes of Analgesics (cont’d) COX-2 inhibitors These drugs have been derived from NSAIDs. Opiates and morphinomimetics Morphine, the archetypalopioid, and various other substances (e.g. codeine, oxycodone, hydrocodone, dihydromorphine, pethidine) all exert a similar influence on the cerebralopioid receptor system. Flupirtine Flupirtine is a centrally acting K+ channel opener with weak NMDA antagonist properties. It is used in Europe for moderate to strong pain and migraine and its muscle relaxant properties.
Specific Forms Combinations Found in paracetamol and codeine preparations found in many non-prescription pain relievers. Found in vasoconstrictor drugs such as pseudoephedrine for sinus-related preparations, or with antihistamine drugs for allergy sufferers. Topical or Systemic Topical analgesia is generally recommended to avoid systemic side-effects. Painful joints, for example, may be treated with an ibuprofen- or diclofenac-containing gel
Specific Forms (continued) Psychotropic Agents Tetrahydrocannabinol (THC) and some other cannabinoids, either from the Cannabis sativa plant or synthetic, have analgesic properties, although the use of cannabis derivatives is currently illegal in many countries. A recent study finds that inhaled cannabis is effective in alleviating neuropathy and pain resulting from e.g. spinal injury and multiple sclerosis.
Specific Forms (continued) Atypical and/or adjuventanalgestics Orphenadrine, cyclobenzaprine, scopolamine, atropine, gabapentin, first-generation antidepressants and other drugs possessing anticholinergic and/or antispasmodic properties are used in many cases along with analgesics to potentiate centrally acting analgesics such as opioids when used against pain especially of neuropathic origin and to modulate the effects of many other types of analgesics by action in the parasympathetic nervous system The use of adjuvant analgesics is an important and growing part of the pain-control field and new discoveries are made practically every year. Many of these drugs combat the side effects of opioid analgesics.
Patient Controlled Analgesia (PCA) Patient Controlled Analgesia (PCA) is a method of pain control that gives the patient the power to control their pain. Pain medication is administered through a computerized pump. The pump contains a syringe of pain medication as prescribed by a doctor that is connected directly to a patient’s intravenous (IV) line. The pump is set to deliver a small, constant flow of pain medication. Additional doses can be self-administered as needed by the patient pressing a button.
Safety of PCA Pumps PCA pumps have built in safety features. The total amount of analgesic (pain reliever) that a patient can self-administer is within a safe limit. Because of these features, there is no worry of overdose.
Who uses PCA? Patients recovering from surgery most often are equipped with PCA pumps. Patients coping with other kinds of pain can also use the PCA pump.
Advantages of PCA The physician determines the dosage based on the patient’s weight to prevent overdose. Narcotic addiction can be avoided because the drug is taken on a short-term controlled basis. Pain relief is available around the clock. The PCA unit is programmed to control the dosage; the unit “locks out” if the dosing frequency is exceeded. Most adults and children can use PCA
Disadvantages of PCA The button on the PCA pump can be accidentally pressed, delivering an unneeded dose of medication. If the PCA pump isn’t programmed properly, results include an under-dose or overdose in medicine.
Anesthesia Prefix “an-” means without. Suffix “-esthesia” means feeling, sensation. Anesthesia means without feeling or sensation. Local or general insensibility to pain with or without the loss of consciousness, induced by an anesthetic (drug that produces anesthesia).
Types of Anesthesia There are four main types: Local – numbs one small area of the body. You stay alert and awake Conscious or IV sedation - uses a mild sedative to relax you and pain medicine to relieve pain. You stay awake but may not remember the procedure afterwards. Regional anesthesia- blocks pain in an area of the body, such an arm or leg. Epidural anesthesia, which is sometimes used during childbirth, is a type of regional anesthesia. General anesthesia- affects your whole body. You go to sleep and feel nothing. You have no memory of the procedure afterwards.
Features of Anesthesia There are four features of anesthesia: The lack of motor response to instructions suppression of autonomic and skeletal responses to intraoperative stimuli such as incisions absence of retrospective awareness of pain postoperative amnesia for surgical events such as conversations among the medical team
How Does Anesthesia Work? It is currently unknown how anesthesia works, but there a number of plausible hypotheses. The most common accepted theory is that that general anesthetics operate directly on the central nervous system to temporarily inhibit synaptic transmission (the chemical means by which neural impulses are transmitted between adjacent neurons). This results in a general loss of consciousness that affects sensory awareness in all modalities and at all body loci.
Major Differences Between Analgesia and Anesthesia Analgesia is lack of pain, anesthesia refers to lack of sensation Anesthesia is usually accompanied by analgesia Patients are fully aware and awake while using analgesia; with anesthesia, patient can be either unconscious and asleep or awake and fully comprehensible. Analgesia is patient controlled, anesthesia is controlled by a person specializing in administration of anesthesia.