Sedation, Analgesia & Patient Controlled Analgesia

By Arshad Syahali

SedationDefinition

• Defined as reduction of irritability or agitation by administration of sedative drugs to facilitate a medical procedure or diagnostic procedure

• Among drugs used include– Propofol - Fentanyl– Etomidate - Midazolam– Ketamine -Lorazepam

SedationUses

• Procedures such as endoscopy, vasectomy, Rapid Sequence Intubation or minor surgery

• Also extensively used in the ICU so that patients who are being ventilated tolerate having an endotracheal tube in their trachea

SedationRoutes of Administration

• Intermittent IV as bolus- Midazolam, Lorazepam

• Continuous infusion- Propofol• Transdermal application- Fentanyl• Intramuscular or subcutaneous- Morphine• Regional blocks and epidural- Local

anaesthesia• Oral and rectal

Midazolam

• Short-acting benzodiazepines. • Anxiolytic, amnestic,hypnotic, anticonvulsant skeletal

muscle relaxant, and sedative properties• Fast recovery time, commonly used as premedication for

sedation, less commonly used for induction and maintenance of anesthesia

• Overdose tx is by flumazenil• Available in oral form, IV ,SC,buccal or intranasal and

PerRectal• Drawbacks include tolerance, withdrawal symptoms and

cognitive impairment

Lorazepam

• Short to intermediate acting benzodiazepine• Anxiolytic, amnesic, sedative/hypnotic, anticonvulsant,

antiemetic and muscle relaxant properties• used for the short-term treatment of anxiety, insomnia,

acute seizures including status epilepticus and sedation of hospitalized patients, as well as sedation of aggressive patients

• Overdose tx is by flumazenil• Available in oral form,IV, and IM• Drawbacks include hypotension; confusion, ataxia,

anterograde amnesia and hangover effects

Propofol

• A short-acting, intravenously administered hypnotic agent. Its uses include the induction and maintenance of general anesthesia, sedation for mechanically ventilated adults, and procedural sedation.

• Adverse effects include low blood pressure (mainly through vasodilatation) and transient apnea following induction doses, pain on injection (most frequent), especially in smaller veins. A more serious but rare side effect is dystonia.

Etomidate

• In emergency settings, etomidate is one of the most frequently used sedative hypnotic agents. It is used by physicians for conscious sedation and as a part of a rapid sequence induction to induce anaesthesia.

• It is used as an anaesthetic agent since it has a rapid onset of action and a safe cardiovascular risk profile, and therefore is less likely to cause a significant drop in blood pressure than other induction agents.

Fentanyl

• Intravenous fentanyl is extensively used for anesthesia and analgesia, most often in operating rooms and intensive care units. It is also administered in combination with a benzodiazepine, such as midazolam, to produce procedural sedation and is often used in the management of chronic pain including cancer pain.

SedationRisks

• Airway obstruction, apnea and hypotension are not uncommon during sedation and require the presence of health professionals who are suitably trained to detect and manage these problems.

SedationLevels of sedation

• The American Society of Anesthesiologists defines the continuum of sedation as follows:[2]

Minimal Sedation - Normal response to verbal stimuli.Moderate Sedation - Purposeful response to

verbal/tactile stimulation. (This is usually referred to as "conscious sedation")

Deep Sedation - Purposeful response to repeated or painful stimulation.

General Anesthesia - Unarousable even with painful stimulus.

SedationLevels of sedation

• The Ramsay sedation scale is used to assess the level of sedation of a hospitalized patient. It was described by Michael A. E. Ramsay.

• The scale, from 1 to 6, describes a patient as follows1-anxious and agitated or restless, or both2-co-operative, oriented, and calm3-responsive to commands only4-exhibiting brisk response to light glabellar tap or loud auditory

stimulus5-exhibiting a sluggish response to light glabellar tap or loud

auditory stimulus6-unresponsive

AnalgesiaDefinition

• also known as a painkiller) is any member of the group of drugs used to relieve pain

• In choosing analgesics, the severity and response to other medication determines the choice of agent; the WHO pain ladder, originally developed in cancer-related pain, is widely applied to find suitable drugs in a stepwise manner.

AnalgesiaMajor Classes

• Paracetamol and NSAIDs• COX-2 inhibitors• Opiates and morphinomimetics• Flupirtine• Specific agents

Paracetamol & NSAIDs

• PCM acts centrally rather than peripherally• 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

• Paracetamol has few side effects and is regarded as safe, although intake above the recommended dose can lead to liver damage, which can be severe and life-threatening, and occasionally kidney damage.

• NSAIDs predispose to peptic ulcers, renal failure, allergic reactions, and occasionally hearing loss, and they can increase the risk of hemorrhage by affecting platelet function.

• The use of aspirin in children under 16 suffering from viral illness has been linked to Reye's syndrome, a rare but severe liver disorder.

• These drugs have been derived from NSAIDs. The cyclooxygenase enzyme inhibited by NSAIDs was discovered to have at least 2 different versions: COX1 and COX2. Research suggested that most of the adverse effects of NSAIDs were mediated by blocking the COX1 (constitutive) enzyme, with the analgesic effects being mediated by the COX2 (inducible) enzyme.

• The COX2 inhibitors were thus developed to inhibit only the COX2 enzyme (traditional NSAIDs block both versions in general). These drugs (such as rofecoxib and celecoxib) are equally effective analgesics when compared with NSAIDs, but cause less gastrointestinal hemorrhage in particular.

• However, post-launch data indicated increased risk of cardiac and cerebrovascular events with these drugs; this is probably due to an imbalance in blood coagulation

Opiates & Morphinomimetics

• Morphine, the archetypal opioid, and various other substances (e.g. codeine, oxycodone, hydrocodone, dihydromorphine, pethidine) all exert a similar influence on the cerebral opioid receptor system

• Tramadol is structurally closer to venlafaxine than to codeine and delivers analgesia by not only delivering "opiate-like" effects (through mild agonism of the mu receptor) but also by acting as a weak but fast-acting serotonin releasing agent and norepinephrine reuptake inhibitor

• Opioids, while very effective analgesics, may have some unpleasant side-effects. Patients starting morphine may experience nausea and vomiting (generally relieved by a short course of antiemetics such as phenergan)

• Pruritus (itching) may require switching to a different opioid. Constipation occurs in almost all patients on opioids, and laxatives (lactulose, macrogol-containing or co-danthramer) are typically co-prescribed

• When used appropriately, opioids and similar narcotic analgesics are otherwise safe and effective, however risks such as addiction and the body becoming used to the drug (tolerance) can occur.

Flupirtine

• Flupirtine is a centrally acting K+ channel opener with weak NMDA antagonist properties.

• Used in Europe for moderate to strong pain and migraine and its muscle relaxant properties

• It has no anticholinergic properties and is believed be devoid of any activity on dopamine, serotonin or histamine receptors. It is not addictive and tolerance usually does not develop

Specific agents

• Tricyclic antidepressants, especially amitriptyline, have been shown to improve pain in what appears to be a central manner.

• The exact mechanism of carbamazepine, gabapentin and pregabalin is similarly unclear, but these anticonvulsants are used to treat neuropathic pain with differing degrees of success

Specific forms and uses

• Combinations- eg,PCM plus codeine– significant adverse events, including accidental

overdoses, most often due to confusion which arises from the multiple (and often non-acting) components of these combination

• Topical or systemic-eg ibuprofen or diclofenac containing gel.Capsaicin also used topically. Lidocaine, an anesthetic, and steroids may be injected into painful joints for longer-term pain relief.

Patient Controlled AnalgesiaDefinition

• PCA is any method of allowing a person in pain to administer their own pain relief

• The infusion is programmable by the prescriber.

• If it is programmed and functioning as intended, the machine is unlikely to deliver an overdose of medication

Patient Controlled AnalgesiaRoutes of aministration

• Oral-The most common form of patient-controlled analgesia is self-administration of oral over-the-counter or prescription painkillers.For example, if a headache does not resolve with a small dose of an oral analgesic, more may be taken.

Patient Controlled AnalgesiaRoutes of aministration

• IV-In a hospital setting, a PCA refers to an electronically controlled infusion pump that delivers an amount of intravenous analgesic (usually an opioid) that is set by the patient.Used commonly

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