ACP 212 - Anesthetics & Analgesics Flashcards

General Principles of Medication Administration & Documentation

• Pre-Administration Patient Assessment & Safety Checks:

  • Assess whether the patient's presentation warrants medication intervention.

  • Obtain complete vital signs: Pulse, Respiratory Rate, $SpO_2$, End-Tidal $CO_2$ ($EtCO_2$), Blood Glucose, and Body Temperature.

  • Initiate continuous cardiac monitoring (12-Lead / 15-Lead ECG as indicated).

  • Complete a thorough SAMPLE history (Signs/Symptoms, Allergies, Medications, Past medical history, Last oral intake, Events leading up).

  • Verify the 6 Rights of Medication Administration: Right Patient, Right Drug, Right Dose, Right Time, Right Route, Right Documentation.

  • Verify the 3 C's and E: Color, Clarity, Concentration, and Expiry Date.

  • Confirm that all contraindications have been ruled out.

  • Prepare the patient, team, medication, and resuscitation equipment before drug administration.

• Post-Administration Reassessment Protocol:

  • Continuously assess Level of Consciousness (LOC), Airway, Breathing, and Circulation (ABCs).

  • Repeat full vital sign measurements (Pulse, RR, $SpO_2$, $EtCO_2$, Blood Glucose, Temperature).

  • Continue continuous cardiac monitoring (12-Lead / 15-Lead ECG).

  • Evaluate patient response and efficacy of the administered drug.

  • Make necessary equipment adjustments.

  • Complete detailed patient care record (PCR) charting.

• Patient Care Record (PCR) & Charting Requirements:

  • Detailed patient history and assessments serve as legal proof of the treatment plan.

  • Record all treatments performed in chronological order.

  • Document pre- and post-administration vital signs.

  • Chart SAMPLE history, including specific signs and symptoms.

  • Document specific drug administration parameters: Drug Name, Exact Dose, Route, Specific Rate of Administration, Drug Concentration, Diluent Solution used, Special Equipment utilized, Exact Time of Administration.

  • Narcotic wastage must be witnessed and documented according to federal regulations.

• Formulary Limitations & ACP Responsibilities:

  • Standard drug formularies provide brief overviews and often omit critical parameters such as Onset, Peak, Duration times, Adverse Reactions, Drug Interactions, and Pregnancy/Breastfeeding safety ratings.

  • Advanced Care Paramedics (ACPs) bear full professional responsibility to thoroughly research every drug, maintaining comprehensive knowledge of mechanisms of action, risks, adverse reactions, precautions, contraindications, and safe administration guidelines.

Local Anesthetics

• Chemical Classification:

  • Local anesthetics are divided into two major chemical classes: Esters and Amides.

  • Prototypic Amide: Lidocaine (contains an amine bond).

  • Prototypic Ester: Procaine (contains an ester bond).

• Mechanism of Action:

  • Stop axonal conduction by directly blocking voltage-gated sodium ($Na^+$) channels within the axonal membrane.

  • Prevent sodium influx during action potential generation, preventing nerve cell membrane repolarization and transmission of pain signals.

  • Function as nonselective modifiers of neuronal function: block all accessible action potentials.

  • Non-myelinated neurons are blocked more rapidly than large myelinated neurons.

• Sequential Order of Sensory and Motor Loss:

  • The order in which nerve fiber blockade occurs following local anesthetic administration is:

  1. Temperature sensation

  2. Pain sensation

  3. Touch / Pressure sensation

  4. Proprioception

  5. Motor function

  • Clinical Pearl: Feeling tactile pressure does not mean the local anesthetic has failed, as pain fibers are blocked prior to pressure fibers.

• Co-Administration with Vasoconstrictors:

  • Local anesthetics are sometimes formulated with vasoconstrictors (such as Epinephrine).

  • Vasoconstrictors reduce local blood flow, delaying systemic absorption and prolonging local anesthetic action.

  • Scope of Practice Warning: ACPs do not independently administer local anesthetics containing vasoconstrictors; these formulations are reserved for physician use.

• Local Anesthetic Systemic Toxicity (LAST):

  • Systemic absorption or accidental intravascular injection can cause severe systemic toxicity involving the cardiovascular and central nervous systems.

  • Cardiotoxicity: Bradycardia, heart blocks, reduction of myocardial contractile force, hypotension, and cardiac arrest.

  • CNS Toxicity: Neurological signs typically present first. Early signs include circumoral numbness, tongue numbness, lightheadedness, visual and auditory disturbances, and metallic taste. Progression leads to muscular twitching, unconsciousness, convulsions/seizures, respiratory depression, coma, and respiratory arrest.

• Lidocaine Specific Indications, Contraindications & Dosing Guidelines:

  • Mechanism: Local anesthetic blocking initiation and conduction of nerve impulses by decreasing neuronal membrane permeability to sodium ions.

  • Contraindications & Precautions: Severe heart blocks (AV block), severe SA node dysfunction, known hypersensitivity to amide-type local anesthetics, and caution in severe hepatic/renal impairment or cardiac failure.

  • Intraosseous (IO) Infusion Pain: Administered as a $2\%$ lidocaine preload prior to fluid/medication infusion in conscious adult and pediatric patients.

  • Urethral Anesthesia: Used as a $2\%$ Lidocaine Hydrochloride Jelly ($20\,\text{mg/mL}$) for male urinary catheterization.

  • Subdermal Infiltration (e.g., Suturing):

  • Concentration: $0.5\% - 1\%$

  • Maximum Dose: $4\,\text{mg/kg}$

  • Techniques:

    • Static Technique: Insert needle, aspirate to ensure no blood return, inject local volume, withdraw needle.

    • Continuous Technique: Insert needle, aspirate to confirm no blood return, continuously inject solution while slowly retracting the needle.

• Topical Anesthetic - EMLA (Eutectic Mixture of Local Anesthetics):

  • Composition: Mixture of Lidocaine (lignocaine) $25\,\text{mg/g}$ ($2.5\%$   ) and Prilocaine $25\,\text{mg/g}$ ($2.5\%$   ) available as a $5\%$    cream or dermal patch ($25\,\text{mg}$    lidocaine / $25\,\text{mg}$    prilocaine per patch).

  • Application: Requires clean, intact skin. Apply $5 - 10\,\text{g}$    of cream under an occlusive dressing for $20\,\text{minutes}$    prior to vascular access or minor superficial procedures.

• Topical Ophthalmic Anesthetic - Tetracaine:

  • Class: Ester-type topical local anesthetic.

  • Mechanism: Blocks sodium channels during axonal conduction, preventing repolarization and pain signal transmission from ocular nerve endings.

  • Dosing: Adult and Pediatric: $1 - 3\,\text{drops}$    of $0.5\%$    solution ($0.5\%\,\text{w/v}$    eye drops).

  • Procedure: Contact lenses must be removed prior to instillation.

Sedation Levels, MFI, and General Anesthesia

• Continuum of Sedation:

  • Minimal Sedation (Anxiolysis): Normal response to verbal stimulation. Airway, spontaneous ventilation, and cardiovascular functions remain completely unaffected.

  • Moderate Sedation / Analgesia ("Conscious Sedation"): Purposeful response to verbal or tactile stimulation. No airway intervention required; spontaneous ventilation is adequate; cardiovascular function is maintained.

  • Dissociative Sedation: Induced by agents like Ketamine, characterized by cataleptic state, profound analgesia, and amnesia while retaining protective airway reflexes.

  • Deep Sedation / Analgesia: Purposeful response only after repeated or painful stimulation. Airway intervention may be required; spontaneous ventilation may be inadequate; cardiovascular function is usually maintained.

  • General Anesthesia: Unarousable even with painful stimuli. Airway intervention is often required; spontaneous ventilation is frequently inadequate; cardiovascular function may be impaired. Complete loss of consciousness.

  • Clinical Warning: Always be prepared for a patient to slip into a deeper level of sedation than planned; advanced airway management equipment must be immediately available.

• Balanced Anesthesia:

  • Combination of drugs to achieve safe, controlled anesthesia with loss of consciousness and loss of pain sensitivity. Consists of a Sedative, an Analgesic, and a Neuromuscular Blocking Agent (NMBA).

• Medication Facilitated Intubation (MFI) & Rapid Sequence Intubation (RSI):

  • RSI Definition: Rapid Sequence Intubation, where rapid execution is primary.

  • MFI Definition: Planned, controlled intubation using strategic medication administration steps in a timely manner. Note that a placed endotracheal tube alone does not classify a successful intubation if patient safety and physiological parameters are not maintained.

  • Drug Classes Used: Sedative and anesthetic agents, with or without Neuromuscular Blocking Agents (NMBAs / Paralytics).

  • Indications for Paralytic Administration: Inability to intubate after appropriate sedation and analgesia within approximately $3\,\text{minutes}$, tight jaw rigidity, or persistent diaphragmatic respiratory effort.

  • Crucial Rule: Neuromuscular blocking agents produce muscle paralysis ONLY. They possess zero analgesic or anesthetic properties.

• Malignant Hyperthermia (MH):

  • Pathophysiology: Rare, life-threatening hypermetabolic crisis triggered by volatile inhalational anesthetics or depolarizing muscle relaxants (e.g., Succinylcholine) in genetically susceptible individuals with heat-hypersensitive mutant calcium channel proteins.

  • Mechanism: Gene mutations in ryanodine receptors ($RyR1$) lead to uncontrolled release of calcium ($Ca^{2+}$) from the sarcoplasmic reticulum into the cytoplasm, driving continuous muscle contraction, extreme thermogenesis, and rapid temperature rise.

• Signs & Symptoms: Rapidly rising body temperature, severe muscle rigidity, hypercapnia (elevated $EtCO_2$), tachycardia, arrhythmia, metabolic acidosis.

• Treatment Protocol:

  1. Immediately stop the triggering agent.

  2. Follow ACLS management guidelines.

  3. Administer Dantrolene Sodium (Dantrium, Revonto, Ryanodex).

  • Dantrolene Dosing:

• Malignant Hyperthermia Initial Dose: $1\,\text{mg/kg}$ IV push; repeat up to a cumulative maximum dose of $10\,\text{mg/kg}$.

• Maintenance: Reconstitute and administer $1\,\text{mg/kg}$ every $6\,\text{hours}$ (up to $10\,\text{mg/kg/day}$).

• Neuroleptic Malignant Syndrome (unlabeled use): $1 - 2.5\,\text{mg/kg}$.

Sedative-Hypnotic & Anesthetic Agents

• GABA Receptor Physiology:

  • Gamma-Aminobutyric Acid (GABA) is the principal inhibitory neurotransmitter in the Central Nervous System.

  • Agents such as Benzodiazepines, Barbiturates, Propofol, Volatile Anesthetics, and Etomidate enhance GABA activity at the $GABA_A$ receptor, opening chloride channels and causing neuronal hyperpolarization.

• Glutamate & NMDA Receptor Physiology:

  • Glutamate is the primary excitatory neurotransmitter in the CNS, activating NMDA (N-methyl-D-aspartate) receptors to regulate alertness, wakefulness, motor function, and coordination.

  • Balance between GABA (inhibitory) and Glutamate (excitatory) governs central nervous system arousal.

• Midazolam:

  • Class: Short-acting Benzodiazepine ($GABA_A$ receptor agonist).

  • Properties: Sedative, anxiolytic, amnestic. Midazolam has NO analgesic properties and must be co-administered with an analgesic (e.g., Fentanyl) when treating painful conditions.

  • Administration Requirements: Administer undiluted or diluted with D5W, $0.9\%$ NaCl, or Lactated Ringer's. Inject slowly over at least $2 - 5\,\text{minutes}$. Always verify drug concentration before administration. Monitor LOC and vitals for $2 - 6\,\text{hours}$ post-administration. If patient becomes agitated, hyperactive, or combative after initial dose, select an alternative agent.

  • Pediatric Note: Ketamine is preferred over Midazolam for pediatric MFI.

  • Contraindications & Precautions: Acute narrow-angle glaucoma, severe hypotension.

  • Adult Dosing:

  • Procedural Sedation: Require Systolic $\text{BP} > 100\,\text{mmHg}$.

  • MFI Induction / Post-MFI Maintenance: Require Systolic $\text{BP} > 90\,\text{mmHg}$.

  • Pediatric Dosing:

  • MFI / Maintenance / Procedural Sedation: Require Systolic $\text{BP} > 70 + (2 \times \text{age})\,\text{mmHg}$.

  • Time/Action Profile (Sedation):

  • Intranasal (IN): Onset $5\,\text{min}$; Peak $10\,\text{min}$; Duration $30 - 60\,\text{min}$.

  • Intramuscular (IM): Onset $15\,\text{min}$; Peak $30 - 60\,\text{min}$; Duration $2 - 6\,\text{hr}$.

  • Intravenous (IV): Onset $1.5 - 5\,\text{min}$; Peak rapid; Duration $2 - 6\,\text{hr}$.

• Propofol:

  • Class: Intravenous sedative-hypnotic agent.

  • Properties: Highly lipid-soluble emulsion formulated with egg phospholipids, soybean oil, and glycerol. High risk of bacterial growth; open vials must be used within $6\,\text{hours}$. May be administered IV push undiluted or as an infusion diluted in D5W ($2\,\text{mg/mL}$). Injecting into larger forearm or antecubital veins reduces injection site pain. Propofol has NO analgesic properties and must be paired with an analgesic (e.g., Fentanyl).

  • Propofol Infusion Syndrome (PRIS): Rare, high-mortality syndrome associated with high-dose prolonged infusions ($> 5\,\text{mg/kg/hr}$ for $> 48\,\text{hours}$) or large short-term surgical doses. Characterized by severe metabolic acidosis, hyperkalemia, lipemia, rhabdomyolysis, hepatomegaly, cardiac failure, and renal failure.

  • Contraindications: Hypersensitivity to drug or emulsion (egg phospholipids, soybean oil, glycerol); pregnancy/breastfeeding (crosses placenta, causes neonatal depression); pediatric patients $< 18\,\text{years}$ receiving infusions lasting longer than $3\,\text{hours}$ (Health Canada safety warning regarding intellectual, learning, and developmental disabilities).

  • Precautions: Hypovolemia, shock (lower induction/maintenance doses required), severe hypotension (due to direct arterial vasodilation), increased ICP or compromised cerebral perfusion pressure. Caution in elderly or patients with impaired renal, hepatic, or severe cardiac/respiratory disease. Concomitant fentanyl in pediatrics may induce bradycardia.

  • Adult Dosing:

  • MFI / RSI Induction: $0.5 - 1.5\,\text{mg/kg}$ IV; administer $20\,\text{mg}$ every $10\,\text{seconds}$ until induction achieved.

  • Maintenance Infusion: $25 - 75\,\mu\text{g/kg/min}$ IV (typical range $1 - 3\,\text{mg/kg/hr}$), titration increments of $5\,\mu\text{g/kg/min}$.

  • Procedural Sedation: $0.5 - 1\,\text{mg}$ every $3 - 5\,\text{min}$ at $0.25 - 0.5\,\text{mg/kg}$.

  • Pediatric Dosing:

  • MFI / RSI Induction: $1 - 2\,\text{mg/kg}$ IV; administer $20\,\text{mg}$ every $10\,\text{seconds}$.

  • Maintenance Infusion: $15 - 50\,\mu\text{g/kg/min}$ IV ($1 - 3\,\text{mg/kg/hr}$).

  • Procedural Sedation: $1 - 2\,\text{mg}$ every $3 - 5\,\text{min}$ at $0.5\,\text{mg/kg}$.

  • Time/Action Profile (Loss of Consciousness):

  • Intravenous (IV): Onset $40\,\text{sec}$; Peak unknown; Duration $3 - 5\,\text{min}$.

• Ketamine:

  • Class: Schedule I controlled substance; NMDA-type glutamate receptor antagonist, partial $\mu$-opioid agonist, and minor muscarinic inhibitor.

  • Mechanism: Produces a state of dissociative anesthesia (the patient feels detached from their environment). Possesses sympathomimetic properties (increases/maintains heart rate and blood pressure, preserves airway reflexes and respiratory drive, causes bronchodilation).

  • Emergence Reactions: Occur in approximately $12\%$ of patients upon awakening (hallucinations, vivid dreams, confusion, agitation). Can be prevented or treated by co-administering Versed (Midazolam).

  • Hypersalivation: Induces tracheobronchial secretions; maintain suction equipment ready. Treat excessive secretions with Atropine $0.02\,\text{mg/kg}$ IV (maximum single dose $1\,\text{mg}$).

  • Rapid Injection Risk: Rapid IV push can trigger transient apnea, aspiration, or laryngospasm.

  • Pediatric MFI: Agent of choice for pediatric MFI.

  • Administration Routes: IV push undiluted; IV infusion mixed with NS or D5W to a concentration of $1 - 2\,\text{mg/mL}$.

  • Time/Action Profile: Onset $30\,\text{seconds}$; Peak unknown; Duration $5 - 10\,\text{minutes}$.

  • Dosing Parameters:

  • MFI Induction (Adult & Pediatric): $1.5 - 2\,\text{mg/kg}$ IVP or $4 - 5\,\text{mg/kg}$ IM.

  • Maintenance Sedation Post-MFI: $0.5 - 1\,\text{mg/kg}$ IVP PRN or infusion at $1 - 3\,\text{mg/kg/hr}$.

  • Procedural Sedation / Violent Patient Control: $1 - 2\,\text{mg/kg}$ IVP over $1\,\text{min}$ or $2 - 4\,\text{mg/kg}$ IM.

  • Acute Pain Management (Adult & Pediatric): $0.2 - 0.5\,\text{mg/kg}$ SIVP/IO PRN every $5\,\text{minutes}$, or continuous infusion at $0.1 - 0.2\,\text{mg/kg/hr}$ (for transport $> 30\,\text{minutes}$; mix $200\,\text{mg}$ in $100\,\text{mL}$ NS/D5W = $2\,\text{mg/mL}$).

Pain Physiology & Opioid Analgesics

• Pain Concepts & Assessment:

  • Pain Definition: An unpleasant sensory and emotional experience associated with actual or potential tissue damage.

  • Pain Threshold: The minimum intensity of a noxious stimulus required for a person to perceive pain.

  • Pain Tolerance: The maximum duration or intensity of pain that a person is willing to endure.

  • Perform OPQRST assessment (Onset, Provocation, Quality, Radiation, Severity, Timing) and use standardized pain rating scales (e.g., Wong-Baker FACES 0–10 scale) before and after administering analgesics.

• Pain Classification:

  • By Duration:

  • Acute Pain: Intense, sudden onset, sharp, well-localized.

  • Persistent / Chronic Pain: Lasts $3 - 6\,\text{months}$ or longer; dull, aching, persistent.

  • By Source / Anatomical Origin:

  • Superficial Pain: Arises from skin or mucous membranes.

  • Deep Pain: Occurs in deep tissues, joint structures, or bones.

  • Vascular Pain: Originates from vascular structures.

  • Referred Pain: Perceived at a location distant from the site of origin.

  • Somatic Pain: Arises from skeletal muscles, ligaments, or joints.

  • Visceral Pain: Originates from internal organs or smooth muscle tissue.

  • Phantom Pain: Pain perceived in an anatomical structure that has been surgically or traumatically amputated.

  • Central Pain: Caused by dysfunction or lesion within the CNS.

  • Cancer Pain: Complex pain syndrome secondary to tumor infiltration or treatment.

• Gate Control Theory of Pain Transmission:

  • Four Primary Processes:

  1. Transduction: Tissue injury triggers chemical release (prostaglandins, bradykinin, serotonin, substance P, histamine, potassium) from injured cells, converting mechanical/thermal/chemical stimuli into electrochemical action potentials.

  2. Transmission: Pain signals travel along peripheral nerve fibers:

     • $A\delta$ Fibers: Large, myelinated fibers carrying fast, sharp, harm-related pain; stimulation closes the spinal "gate."

     • C Fibers: Small, unmyelinated fibers carrying slow, dull, poorly localized aching pain; stimulation opens the spinal "gate."

     • Signals travel up the ascending spinothalamic tract through the dorsal horn to the thalamus and cerebral cortex.

  3. Perception: Subjective conscious experience of pain processed in the CNS ($\mu$-opioid receptors involved).

  4. Modulation: Descending spinal pathways release endogenous neurotransmitters (enkephalins, endorphins, dynorphins, serotonin, norepinephrine, GABA) which bind to opioid receptors in the dorsal horn, closing the gate and inhibiting pain impulse transmission.

• Opioid Receptor Physiology & Endogenous Peptides:

  • Endogenous Peptides: Three families exist in the body: Enkephalins, Endorphins, and Dynorphins.

  • $\mu$ (Mu) Receptors: Responsible for CNS and PMS analgesia, respiratory depression, euphoria, sedation, physical dependence, and decreased GI motility.

  • $\kappa$ (Kappa) Receptors: Responsible for spinal analgesia, sedation, decreased GI motility, and dysphoria.

  • Opioid Classes by Receptor Function:

  • Pure Opioid Agonists (Morphine, Codeine, Meperidine, Fentanyl): Agonists at both $\mu$ and $\kappa$ receptors; potent analgesics.

  • Agonist-Antagonist Opioids (Pentazocine, Nalbuphine, Butorphanol): $\mu$ receptor antagonists and $\kappa$ receptor agonists; weaker analgesics.

  • Partial Agonists / Agonist-Antagonists (Buprenorphine): Partial agonist/antagonist at $\mu$ and $\kappa$ receptors.

  • Pure Opioid Antagonists (Naloxone): Antagonist at both $\mu$ and $\kappa$ receptors; reverses opioid-induced depression.

• Opioid-Induced Neurotoxicity (OIN):

  • Caused by toxic metabolite accumulation during prolonged or high-dose opioid therapy due to impaired clearance.

  • Clinical Presentation: Delirium, severe agitation, myoclonus, hyperalgesia, and paradoxical worsening of pain despite escalating opioid doses.

  • Distinction: Classic opioid overdose presents with CNS and respiratory depression; OIN presents with agitation, myoclonus, and worsening pain.

• Morphine Sulfate:

  • Prototype Pure Opioid Agonist: Binds primarily to $\mu$ receptors (and $\kappa$ receptors) in the CNS; reduces intracellular calcium influx, inhibiting neurotransmitter release from peripheral nociceptive neurons.

• Indications: Moderate to severe acute or chronic pain (dull constant pain, or sharp pain at high doses); Acute Coronary Syndrome (ACS) chest pain unresponsive to nitrates. Relieves pain without affecting other senses or causing loss of consciousness within therapeutic range. Provides beneficial sedation, euphoria, and anxiety reduction.

• Adverse Effects: Hypotension (caused by histamine release and blunted baroreceptor reflex via venous/arteriolar dilation), severe respiratory depression (enhanced by concurrent alcohol, barbiturates, or benzodiazepines), nausea/vomiting (direct stimulation of the medullary chemoreceptor trigger zone), constipation, acute urinary retention (increased bladder sphincter tone, especially in benign prostatic hypertrophy), local skin flushing/itching/wheal formation at injection site.

• Pharmacokinetics: Extensive hepatic first-pass metabolism; oral doses must be substantially larger than parenteral doses. Inactivated metabolites excreted by kidneys. Prolonged action in hepatic/renal impairment.

• Special Populations: Increases birth defect risk by $2 - 3\times$ in early pregnancy; suppresses uterine contractions and causes neonatal respiratory depression during labor. Extreme sensitivity in neonates, pediatric, and elderly patients.

• Contraindications: Hypersensitivity, MAO inhibitor / tricyclic / phenothiazine use within 14 days (risk of Serotonin Syndrome), acute severe bronchial asthma, severe respiratory/CNS depression, hypotension (Systolic $\text{BP} < 90\,\text{mmHg}$).

• Precautions: RV infarction (extreme caution), head trauma (increased ICP), severe renal/hepatic/pulmonary disease, hypothyroidism, bowel obstruction, prostatic hypertrophy.

• Adult Dosing:

  • Pain Control: $0.1\,\text{mg/kg}$ or $5\,\text{mg}$ SIVP.

  • ACS: $2 - 5\,\text{mg}$ SIVP every $5 - 10\,\text{min}$.

• Pediatric Dosing:

  • Pain Control: $0.1\,\text{mg/kg}$ SIVP (dilute $10\,\text{mg/mL}$ ampoule with $9\,\text{mL}$ Normal Saline to yield $1\,\text{mg/mL}$); maximum single dose $5 - 10\,\text{mg}$.

• Time/Action Profile (Analgesia):

  • Oral (PO): Onset unknown; Peak $60\,\text{min}$; Duration $4 - 5\,\text{hr}$.

  • Oral Extended-Release (PO-ER): Onset unknown; Peak $3 - 4\,\text{hr}$; Duration $8 - 24\,\text{hr}$.

  • Intramuscular (IM): Onset $10 - 30\,\text{min}$; Peak $30 - 60\,\text{min}$; Duration $4 - 5\,\text{hr}$.

  • Subcutaneous (Subcut): Onset $20\,\text{min}$; Peak $50 - 90\,\text{min}$; Duration $4 - 5\,\text{hr}$.

  • Rectal (Rect): Onset unknown; Peak $20 - 60\,\text{min}$; Duration $3 - 7\,\text{hr}$.

  • Intravenous (IV): Onset rapid; Peak $20\,\text{min}$; Duration $4 - 5\,\text{hr}$.

  • Fentanyl Citrate:

• Synthetic Opioid Agonist: High affinity for $\mu$ receptors; approximately $100\times$ more potent than Morphine. Minimal $\kappa$ receptor action and less hypotensive effect than Morphine. Metabolized in liver; $10 - 25\%$ excreted unchanged by kidneys.

• Indications: Moderate to severe acute pain, breakthrough pain in opioid-tolerant/cancer patients, balanced anesthesia, procedural sedation, MFI induction, and post-MFI maintenance sedation.

• Rigid Chest Syndrome: Rare, severe complication involving respiratory muscle spasm, severe dyspnea, elevated airway pressures, and inability to ventilate.

  • Causes: High doses ($> 5\,\mu\text{g/kg}$), rapid IV injection, or rapid flushing of IV line.

  • Prevention: Administer SIVP over $2 - 5\,\text{minutes}$; flush lines slowly; dilute with NS ($100\,\mu\text{g}$ in $10\,\text{mL}$ NS = $10\,\mu\text{g/mL}$).

  • Management: Not reversible with Naloxone (Narcan). Assist/manage ventilation (may require intubation) and switch to Ketamine for analgesia.

• Contraindications: Hypersensitivity, MAO inhibitors within 14 days, Systolic $\text{BP} < 90\,\text{mmHg}$.

• Precautions: Elderly/pediatric caution, head injury, cardiac arrhythmias, severe renal/hepatic impairment, diabetes, alcoholism, adrenal insufficiency, hypothyroidism, breastfeeding.

• Adult Dosing:

  • Analgesia: $0.5 - 1\,\mu\text{g/kg}$ SIVP/IO/IM every $5\,\text{min}$ PRN (single max dose $100\,\mu\text{g}$, total max dose $250\,\mu\text{g}$).

  • ACS: $25\,\mu\text{g}$ SIVP every $5 - 10\,\text{min}$ PRN (total max dose $250\,\mu\text{g}$).

  • MFI: $1 - 2\,\mu\text{g/kg}$ IVP single max dose $100\,\mu\text{g}$.

  • Maintenance Sedation: $0.5 - 1\,\mu\text{g/kg}$ SIVP/IO/IM every $5 - 10\,\text{min}$ (max $100\,\mu\text{g}$) OR Infusion $1 - 2\,\mu\text{g/kg/hr}$ ($50 - 200\,\mu\text{g/hr}$; mix $500\,\mu\text{g}$ in $100\,\text{mL}$ NS/D5W = $5\,\mu\text{g/mL}$).

  • Procedural Sedation: $0.5 - 1\,\mu\text{g/kg}$ SIVP every $10\,\text{min}$ PRN (max $100\,\mu\text{g}$).

• Pediatric Dosing:

  • Analgesia (IV/IM): $0.5 - 1\,\mu\text{g/kg}$ slow IVP/IM every $5 - 10\,\text{min}$ PRN (single max dose $50\,\mu\text{g}$, total cumulative max $150\,\mu\text{g}$).

  • Analgesia (IN): $2\,\mu\text{g/kg}$ Intranasal ($50\,\mu\text{g}$ per nostril) every $15\,\text{min}$ PRN (single max dose $100\,\mu\text{g}$, total cumulative max $150\,\mu\text{g}$).

  • MFI: $1 - 2\,\mu\text{g/kg}$ IVP single max dose $50\,\mu\text{g}$.

  • Maintenance Sedation: $0.5 - 1\,\mu\text{g/kg}$ every $5 - 10\,\text{min}$ (max $50\,\mu\text{g}$) OR Infusion $0.5 - 2\,\mu\text{g/kg/hr}$.

  • Procedural Sedation: $0.5 - 1\,\mu\text{g/kg}$ (max $50\,\mu\text{g}$).

• Time/Action Profile (Analgesia):

  • Intramuscular (IM): Onset $7 - 15\,\text{min}$; Peak $20 - 30\,\text{min}$; Duration $1 - 2\,\text{hr}$.

  • Intravenous (IV): Onset $1 - 2\,\text{min}$; Peak $3 - 5\,\text{min}$; Duration $0.5 - 1\,\text{hr}$.

  • Hydromorphone (Dilaudid):

• Potency Equivalent: $2\,\text{mg}$ IV Hydromorphone is equivalent to $10\,\text{mg}$ IV Morphine.

• Administration: Give SIVP over $2 - 5\,\text{minutes}$ undiluted or diluted with $4 - 5\,\text{mL}$ NS. IM injection is not recommended due to variable absorption rates.

• Formulation Duration: Prolonged-release (PR) PO tablets have a $24\text{-hour}$ repeat time; Controlled-release (CR) PO tablets have a $12\text{-hour}$ repeat time.

• Contraindications: Hypersensitivity to drug/sulphites, MAO inhibitors/tricyclics within 14 days, severe asthma/COPD/emphysema, cor pulmonale, GI/ileus obstruction, severe respiratory depression, pregnancy/breastfeeding.

• Adult Dosing (Medical Direction Required in AB):

  • Immediate Release Oral: $2 - 4\,\text{mg}$ PO q4h PRN.

  • Parenteral IV: $0.25 - 1\,\text{mg}$ SIVP q2-3h PRN.

  • Continuous Infusion: $0.5 - 3\,\text{mg/hr}$ or $7 - 15\,\mu\text{g/kg/hr}$ (concentration $200 - 1000\,\mu\text{g/mL}$).

  • SC / IM: $2 - 4\,\text{mg}$ q4-6h PRN.

  • Elderly / Renal / Hepatic Failure: Reduce dose by $0.2\,\text{mg}$ in elderly; reduce dose by $25\%$ to $50\%$ in renal/hepatic failure.

• Pediatric Dosing ($< 50\,\text{kg}$):

  • Oral: $0.03 - 0.06\,\text{mg/kg}$ PO q4h PRN (max $4\,\text{mg}$).

  • IV: $15\,\mu\text{g/kg}$ ($0.015\,\text{mg/kg}$) SIVP q3-6h PRN.

  • Continuous Infusion: $200\,\mu\text{g/hr}$ ($0.2\,\text{mg/hr}$); concentrations $10\,\mu\text{g/mL}$ or $40\,\mu\text{g/mL}$.

• Pediatric Dosing ($> 50\,\text{kg}$):

  • Oral: $2 - 4\,\text{mg}$ PO q4h PRN.

  • IV: $200 - 600\,\mu\text{g}$ ($0.2 - 0.6\,\text{mg}$) SIVP q2-4h PRN.

  • Infusion: $300\,\mu\text{g/hr}$ ($0.3\,\text{mg/hr}$).

  • IM / SC: $800 - 2000\,\mu\text{g}$ ($0.8 - 2.0\,\text{mg}$) q4-6h PRN.

  • Oxycodone (Oxycontin):

• Long-acting oral opioid agonist. $15 - 20\,\text{mg}$ Oral Oxycodone is equivalent to $10\,\text{mg}$ Subcutaneous Morphine ($10\,\text{mg}$ SC Oxycodone is equivalent to $15\,\text{mg}$ SC Morphine). "Cotin" denotes continuous release formulation. Adult dosing only.

  • Meperidine (Demerol):

• Strong $\mu$ and $\kappa$ agonist. Depresses pain impulse transmission at spinal cord level. Not recommended for routine pain control due to toxic metabolite (normeperidine) accumulation. Dilute with $10\,\text{mL}$ NS to $10\,\text{mg/mL}$ and administer slowly over $5\,\text{minutes}$. Rapid push causes respiratory depression or apnea.

  • Buprenorphine:

• Partial agonist at $\mu$ receptors, partial antagonist at $\kappa$ receptors. Used for acute pain, severe chronic pain, suppression of opioid withdrawal symptoms, and pain management in patients with a history of opioid addiction.

Non-Opioid Analgesics, NSAIDs, and Inhalational Agents

• Cyclooxygenase (COX) Isoenzymes:

  • COX-1 (Constitutive): Present in all tissues. Protects gastric mucosa (reduces acid, increases bicarbonate/mucus), promotes platelet aggregation via Thromboxane $A_2$ ($TXA_2$), maintains renal submucosal blood flow.

  • COX-2 (Inducible): Produced at tissue injury sites. Promotes inflammation, sensitizes pain nociceptors, mediates fever in the brain, promotes renal vasodilation, mediates uterine contractions.

• Inhibition Consequences:

  • Inhibiting COX-1: Causes gastric mucosal erosion/ulceration, bleeding risks (inhibits $TXA_2$), renal impairment. Provides protection against MI/stroke via reduced platelet aggregation.

  • Inhibiting COX-2: Suppresses inflammation, relieves pain, reduces fever. Can cause renal impairment and increased cardiovascular risk (MI/stroke) due to suppressed vasodilation.

• Ibuprofen:

  • Class: Non-selective COX-1 and COX-2 inhibitor NSAID.

  • Indications: Mild to moderate pain (musculoskeletal, dysmenorrhea, dental, arthritis); Fever reduction for body temperature over $39^\circ\text{C}$.

  • Health Canada Warning: High doses ($> 2400\,\text{mg/day}$) or prolonged use carry serious cardiovascular thrombotic risks (MI and stroke).

  • Contraindications: Active GI bleeding or ulcers, hemorrhages/coagulation disorders, cerebral bleeding, CABG perioperative pain, recent MI, severe heart failure, 3rd trimester pregnancy ($> 30\,\text{weeks}$ gestation), infants $< 6\,\text{months}$ of age.

  • Precautions: Asthma, aspirin intolerance, renal/hepatic disease, dehydration, concurrent antihypertensives/diuretics. Avoid between 20–30 weeks gestation if possible.

  • Adult Dosing: $200 - 400\,\text{mg}$ PO every $4\,\text{hours}$ PRN; maximum daily dose $1200\,\text{mg/day}$.

  • Pediatric Dosing: $10\,\text{mg/kg}$ PO every $4 - 6\,\text{hours}$ PRN; maximum single dose $400\,\text{mg}$; maximum daily dose $40\,\text{mg/kg/day}$ up to $1200\,\text{mg/day}$.

  • Time/Action Profile:

  • PO (Antipyretic): Onset $0.5 - 2.5\,\text{hr}$; Peak $2 - 4\,\text{hr}$; Duration $6 - 8\,\text{hr}$.

  • PO (Analgesic): Onset $30\,\text{min}$; Peak $1 - 2\,\text{hr}$; Duration $4 - 6\,\text{hr}$.

  • PO (Anti-inflammatory): Onset $\le 7\,\text{days}$; Peak $1 - 2\,\text{wk}$; Duration unknown.

• Ketorolac (Toradol):

  • Class: Potent non-selective COX-1 and COX-2 inhibitor NSAID with analgesic efficacy comparable to Morphine.

  • Indications: Moderate to severe acute pain (kidney stones/renal colic, cholecystitis, musculoskeletal injuries, vascular headaches).

  • Ceiling Effect: Doses above recommended levels do not increase efficacy but significantly increase side effects ($10\,\text{mg}$ IM is as effective as $30\,\text{mg}$ IM; $15\,\text{mg}$ IV is as effective as $30\,\text{mg}$ IV).

  • DRESS Warning: Monitor for Drug Reaction with Eosinophilia and Systemic Symptoms (fever, rash, lymphadenopathy, facial swelling); discontinue immediately if observed.

  • Contraindications: Active peptic ulcer disease, recent GI bleeding, planned major surgery, CABG pain, active cerebrovascular bleeding, advanced renal impairment or volume depletion, pregnancy/labor/delivery, breastfeeding, concurrent Pentoxifylline or Probenecid.

  • Adult Dosing: $10 - 30\,\text{mg}$ SIVP IV or IM every $6\,\text{hours}$; maximum daily dose $120\,\text{mg/day}$.

  • Elderly ($> 65\,\text{years}$) / Weight $< 50\,\text{kg}$ / Moderate Renal Impairment: $10 - 15\,\text{mg}$ SIVP IV every $6\,\text{hours}$; maximum daily dose $60\,\text{mg/day}$.

  • Pediatric Dosing ($2 - 16\,\text{years}$, $< 50\,\text{kg}$): $0.4 - 1\,\text{mg/kg}$ SIVP IV or IM every $6\,\text{hours}$ (routine single dose $0.5\,\text{mg/kg}$; max single dose $15\,\text{mg}$ IV or $30\,\text{mg}$ IM).

  • Time/Action Profile:

  • Oral (PO): Onset $0.5 - 1\,\text{hr}$; Peak $1 - 3\,\text{hr}$; Duration $3 - 8\,\text{hr}$.

  • Intramuscular / Intravenous (IM/IV): Onset $10\,\text{min}$; Peak $1 - 2\,\text{hr}$; Duration $6\,\text{hr}$.

• Acetaminophen (Tylenol):

  • Class: Non-opioid central analgesic and antipyretic. Selectively inhibits COX in the CNS. Lacks peripheral anti-inflammatory activity, does not inhibit platelets, and does not cause gastric erosion or renal impairment.

  • Metabolism: $85 - 95\%$ liver metabolism; toxic levels lead to hepatic necrosis and acute liver failure. Excreted via kidneys.

  • Indications: Mild to moderate pain; Fever reduction for body temperature over $38^\circ\text{C}$.

  • Contraindications: Severe active liver disease or hepatic impairment, Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency, hypersensitivity to additives (e.g., alcohol, aspartame, saccharin, sugar, or tartrazine/yellow #5 dye in coated tablets).

  • Adult Dosing:

  • Oral (PO): $325 - 1000\,\text{mg}$ PO every $4 - 6\,\text{hours}$ PRN.

  • Rectal (PR): $325 - 650\,\text{mg}$ PR every $4 - 6\,\text{hours}$ PRN.

  • Maximum Daily Dose: Healthy adults: $4\,\text{g/24hr}$ ($4000\,\text{mg}$); Geriatric, hepatic impairment, or chronic alcohol use: $2\,\text{g/24hr}$ ($2000\,\text{mg}$).

  • Pediatric Dosing: $10 - 15\,\text{mg/kg}$ PO or PR every $6\,\text{hours}$ PRN (single max dose $1000\,\text{mg}$; maximum 5 doses in $24\,\text{hours}$).

  • Time/Action Profile:

  • Oral (PO): Onset $0.5 - 1\,\text{hr}$; Peak $1 - 3\,\text{hr}$; Duration $3 - 8\,\text{hr}$.

  • Rectal (Rect): Onset $0.5 - 1\,\text{hr}$; Peak $1 - 3\,\text{hr}$; Duration $3 - 4\,\text{hr}$.

• Methoxyflurane (Penthrox):

  • Class: Volatile inhalational agent (halogenated hydrocarbon); enhances GABA inhibitory pathways in the brain and spinal cord, reducing post-synaptic neurotransmitter release/re-uptake.

  • Indications: Short-term relief of moderate to severe acute trauma pain or medical procedures in conscious adults.

  • Packaging & Delivery: $3\,\text{mL}$ bottle containing $99.9\%$ Methoxyflurane poured into a hand-held vaporized inhaler device for patient self-administration. Onset $1 - 5\,\text{minutes}$; analgesia lasts $25 - 30\,\text{minutes}$.

• Safety & Dosing Limits:

  • Covering the dilutor hole on the inhaler chamber increases vapor concentration for stronger analgesia.

  • Maximum daily dose: $6\,\text{mL/day}$ ($2\,\text{vials}$); maximum weekly dose: $15\,\text{mL/week}$. Doses higher than $5\,\text{MAC}$ per hour lead to clinical toxicity.

  • Occupational Safety: Paramedic exposure limit is maximum 3 doses ($9\,\text{mL}$) per $24\,\text{hours}$ in an enclosed space. When used in an ambulance, high vehicle ventilation and exhaust fans must be active, and cab partition closed.

  • Do not use if temperature exceeds $40^\circ\text{C}$. Do not shake bottle; rotate gently.

• Contraindications: Age $< 18\,\text{years}$, altered LOC, head injury, significant renal or hepatic impairment, personal/family history of malignant hyperthermia, hemodynamic instability/shock, respiratory depression, concurrent CNS depressants or opioids.

  • Nitrous Oxide ($N_2O$):

• Class: Inhalational gas blend ($50\% N_2O / 50\% O_2$); potent analgesic, weak anesthetic. Inhaling $20\%$ Nitrous Oxide provides analgesia equivalent to $5 - 7\,\text{mg}$ IV Morphine.

• Indications: Musculoskeletal pain (fractures, dislocations), transcutaneous pacing, burns, BLS suspected ischemic chest pain, active labor in pregnancy.

• Administration: Self-administered via demand valve mask until pain relief is achieved or patient drops the mask.

• Contraindications: Inability to follow commands, altered LOC, severe COPD, traumatic chest injuries, suspected pneumothorax, bowel obstruction (abdominal pain with distension), decompression sickness (scuba diving within last $48\,\text{hours}$), pregnancy outside active labor.

• Precautions & Special Operations: Use in well-ventilated area. Caution in pulmonary hypertension (possesses pulmonary vasoconstrictor and cardiac depressant properties). May cause nausea and vomiting. Invert tank 3 times prior to use. Do not use outdoors if ambient temperature is below $-6^\circ\text{C}$ or if frost forms on the cylinder.