Analgesic Drugs Analgesics Medications that relieve pain without causing loss of consciousness o Moderate to severe pain Painkillers Opioid analgesics Adjuvant analgesic drugs o Enhance effect or to assist with pain relief Pain An unpleasant sensory and emotional experience associated with actual or potential tissue damage A personal and individual experience Whatever the patient says it is Exists when the patient says it exists Nociception Pain results from stimulation of sensory nerve fibers called nociceptors These receptors transmit pain signals from various body regions to the spinal cord and brain Pain Threshold Level of stimulus needed to produce the perception of pain A measure of the physiologic response of the nervous system Pain Tolerance The amount of pain a person can endure without it interfering with normal function Varies from person to person Subjective response to pain not a physiologic function Varies by attitude environment culture ethnicity Classification of Pain by Onset and Duration Acute pain o Sudden onset o Usually subsides once treated Chronic pain o Persistent or recurring o Lasts 3 to 6 months o Often difficult to treat Classification of Pain Somatic muscle skeletal Visceral organ pain Superficial sharp tingly Deep deep somatic pain Vascular neuropathy like a constant pin prick Referred common in hospital pain appendicitis gall stones Neuropathic stroke pt sharp Phantom in an extremity that has been amputated Cancer anywhere Central CNS pain pins and needles Gate Theory of Pain Transmission Most common and well described theory Uses the analogy of a gate to describe how impulses from damaged tissues are sensed in the brain Many current pain management strategies are aimed at altering this system Pain Transmission Tissue injury causes the release of o Bradykinin o Histamine o Potassium o Prostaglandins o Serotonin These substances stimulate nerve endings starting the pain process The nerve impulses enter the spinal cord and travel up to the brain The point of spinal cord entry or the gate is the dorsal horn This gate regulates the flow of sensory impulses to the brain Closing the gate stops the impulses If no impulses are transmitted to higher centers in the brain there is no pain perception Body has endogenous neurotransmitters o Enkephalins o Endorphins Produced by body to fight pain Bind to opioid receptors Inhibit transmission of pain by closing gate Rubbing a painful area with massage or liniment stimulates large sensory fibers Result o Closes gate o Reduces pain sensation Treatment of Pain in Special Situations PCA and PCA by proxy Patient comfort vs fear of drug addiction Opioid tolerance Use of placebos Recognizing patients who are opioid tolerant Breakthrough pain Synergistic effect Adjuvant Drugs Assist primary drugs in relieving pain o NSAIDs o Antidepressants o Anticonvulsants sedatives o Corticosteroids if the inflammation is causing the pain Example Adjuvant drugs for neuropathic pain o amitriptyline antidepressant o gabapentin or pregabalin anticonvulsants Opioid Drugs Synthetic drugs that bind to the opiate receptors to relieve pain Very strong pain relievers Opioid Ceiling Effect Drug reaches a maximum analgesic effect Analgesia does not improve even with higher doses o pentazocine o Nalbuphine Mimic opioid safe to use in pt that are addicted Partial antagonists Synthetic Opioid Analgesics Examples o codeine sulfate o meperidine HCl Demerol potential to cause more side effects o methadone HCl Dolophine rehab of subs abuse pts o morphine sulfate use IV o hydromorphone o fentanyl Duragesic most potent o oxycodone o Others Mechanism of Action o Three classifications based on their actions Agonist produce response Partial agonist partial response Antagonist counteract the opioid Indications o Main use to alleviate moderate to severe pain o Often given with adjuvant analgesic drugs to assist primary drugs with pain relief o Opioids are also used for Cough center suppression codeine Treatment of diarrhea Balanced anesthesia Contraindications o Known drug allergy o Severe asthma Itching is a normal side effect o Use with extreme caution in patients with Respiratory insufficiency Elevated intracranial pressure Don t give narcotics Morbid obesity and or sleep apnea Paralytic ileus bowel that is not moving Can cause constipation Pregnancy Crosses placental barrier Adverse Effects o CNS depression Leads to respiratory depression Most serious adverse effect o Nausea and vomiting o Urinary retention o Diaphoresis and flushing o Pupil constriction miosis o Constipation o Itching Tolerance o A common physiologic result of chronic opioid treatment o Result larger dose is required to maintain the same level of analgesia Physical Dependence o Physiologic adaptation of the body to the presence of an opioid o Opioid tolerance and physical dependence are expected with long term opioid treatment and should not be confused with psychologic dependence addiction Psychologic Dependence o A pattern of compulsive drug use characterized by a continued craving for an opioid and the need to use the opioid for effects other than pain relief Toxicity and Management of Overdose o naloxone Narcan o naltrexone ReVia o Regardless of withdrawal symptoms when a patient experiences severe respiratory depression an opioid antagonist should be given o Opioid withdrawal opioid abstinence syndrome o Manifested as Anxiety irritability chills and hot flashes joint pain lacrimation rhinorrhea diaphoresis nausea vomiting abdominal cramps diarrhea confusion Interactions o Alcohol number one o Antihistamines the ones that cause drowsiness o Barbiturates o Benzodiazepines o Monoamine oxidase inhibitors Nursing Implications o Oral forms should be taken with food to minimize gastric upset o Ensure safety measures such as keeping side rails up to prevent injury o Withhold dose and contact physician if there is a decline in the patient s condition or if vital signs are abnormal especially if respiratory rate is less than 10 to 12 breaths min o Check dosages carefully o Follow proper administration guidelines for IM injections including site rotation o Follow proper guidelines for IV administration including dilution rate of administration and so on o Constipation is a common adverse effect and may be prevented with adequate fluid and fiber intake o Instruct patients to follow directions for administration carefully and to keep a record of their pain experience and response to treatments