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Objectives - Describe medication regulation in the United States and the schedule system.- Understanding pharmacology is paramount to the paramedic’s success. Dozens of medications are available that could remedy a patient’s condition and improve his or her condition long before arriving at the hospital. Medication Regulation In the 20th century, major laws affecting medication regulation in the United States were passed. Major U.S. Laws Regulating Medications
The Comprehensive Drug Abuse Prevention and Control Act led to the scheduling system (Table 2.2) that classifies all medications with a potential for abuse. Schedule System for Controlled Substances
Sources, Forms, and Names Medications are derived from multiple different sources beyond synthetic preparation in a laboratory. Medications such as atropine, digoxin, and morphine come from plant sources. Heparin and insulin are most commonly produced in and collected from animals. Many antibiotics are produced from microorganisms such as bacteria and molds. Minerals are essential to our diet and can be mined from the earth. Regardless of the source, however, by the time they reach the consumer, they have been put under rigorous quality control measures to ensure what the label says is what the patient gets.
Medications also can be delivered to the patient in a multitude of forms, which are as follows: - Tablet: powder compressed into a solid to be swallowed- - - Medications can be referred to by any of 3 names. Depending on the medication being requested, the typical person may use either the generic or trade name but never the chemical name. Medication Terms The following terms are used to describe medications: - Indications. Why a drug is given—the symptoms it is used to treat. - Contraindications. Reasons to not give a medication. There may be relative contraindications when a medication should be avoided in favor of another medication but may be given in extreme or emergent circumstances. Absolute contraindications are reasons the drug should never be given at any time, regardless of the circumstance. - Adverse Reactions or Side Effects. These are nontherapeutic effects that a medication has on the body. They are not desired and often can be severe enough for a person to stop taking the medication. Side effects range from annoying or bothersome to dangerous or life threatening. A patient may or may not experience 1 or all of a drug’s listed side effects.-
2. Physiology of Pharmacology Pharmacology is the study of medications and their effects on the body. This section addresses the pharmacodynamics and the pharmacokinetics of medications. Pharmacodynamics Pharmacodynamics is the process a drug performs to alter processes in the body to bring about a desired effect. It also includes the overall response of the body to a medication. Here, the discussion focuses on the ways a drug impacts the body as well as other responses to the medication. The human body contains many different receptors (Table 2.3) on its cells that allow it to respond naturally to changes in blood sodium, danger, or anxiety, to name a few. These receptors are there for endogenous chemicals, such as norepinephrine, dopamine, or acetylcholine, to carry out the effects these chemicals are produced to cause. Some medications are designed to stimulate or inhibit these receptors to produce certain effects. These are called exogenous chemicals because they originate outside the body, but for our purposes here, the term medications will be used. Agonist medications bind to these receptor sites and not only act like the endogenous chemical that would naturally stimulate that receptor but also initiate a magnified or enhanced cellular response than the endogenous chemical would produce. Antagonists, therefore, produce the opposite effect on the receptor as the agonist (think anti-agonist). These medications can work by either competitive inhibition or noncompetitive inhibition. In competitive inhibition, the medication binds to the exact same site as the endogenous chemical would use to exert its effects. Although this receptor is blocked, if that receptor’s agonist is increased, it can overpower and replace the antagonist. So, the inhibition of that site will continue until 1 of 2 things happen: the concentration of the antagonist falls or the concentration of the agonist increases and pushes out the antagonist. Noncompetitive inhibition can occur in 1 of 2 ways. First, the medication can bind to a site on the receptor at a location other than the active site, which is the location on the receptor to which the endogenous chemical would bind. This type of binding changes the shape of the area on the receptor to which the agonist chemical would attach; because it can no longer bind, it can no longer exert its agonist effects. The 2nd way noncompetitive inhibition occurs is when the antagonist binds irreversibly to the receptor site. The difference between this and competitive inhibition is that this variety is not influenced by the amount of agonist present; it will still exert its inhibitory effects. Perhaps it should be called irreversible competitive inhibition, which is a better description of it. Both styles of noncompetitive inhibition are irreversible. Receptors and Effects of Stimulation
Medications also exert their therapeutic effects in ways other than targeting the cell receptors. Antibiotics and antifungals are designed to attack certain features of a bacterium or fungus, respectively, which human cells do not possess, such as peptidoglycan on gram-positive bacteria. Chelating agents bind to heavy metals, such as lead, in the blood, which help remove the poison from the body. Electrolytes, such as sodium, magnesium, or calcium, increase the concentration of that electrolyte in the body, which can allow it to function better in all the ways that electrolytes affect the cells of the body. Responses to Medication Side effects and untoward effects were discussed earlier in this guide, both of which are undesired reactions to a medication beyond the medication’s desired therapeutic effect. The therapeutic effect is the desired effect of the medication on the body—why it is given in the first place. All medications have a therapeutic index, also called the therapeutic window, which is the range of concentrations in the body between the minimum amount of drug needed to generate a therapeutic response and the amount that is toxic or lethal. Some drugs have a wide therapeutic index, such as diphenhydramine, which are difficult to overdose; others have a narrow therapeutic index, such as atropine, making overdose easier to achieve. The minimum concentration in the blood needed to generate a therapeutic response is called the threshold. The potency of a medication is based on how much of the medication is needed to achieve the threshold. For example, the potency of fentanyl is about 100 times that of morphine sulfate, which is to say that a patient can receive 0.1 mg (100 mcg) of fentanyl and have the same pain relief as from 10 mg morphine. Efficacy is the ability of a medication to carry out the effects it was designed to do. In most cases and with continued use, efficacy tends to decrease as time progresses. This decline in efficacy indicates that the patient is building a tolerance to a medication, which means that the patient requires ever-increasing doses to achieve the same therapeutic effect. Tolerance is caused by the body actually reducing the number of receptors for a given chemical through a process known as down-regulation or increasing the ability to metabolize the medication faster to nontherapeutic forms. Cross-tolerance can be developed when a person develops tolerance for an entire class of medications. Through tolerance, patients can develop a dependence and thus abuse certain medications or classes of medications. The phenomenon of needing more and more medication to achieve the same effect is at least partially responsible for the problems of abuse and dependence, but in many cases, the euphoric or stimulant effects of medications can result in both psychological dependence and physical dependence. Factors Affecting Medication Responses The 1st and perhaps most obvious factor impacting how a medication affects an individual is weight. Weight-based dosing is common in prehospital for dopamine and other pressor medications and analgesics because the size of a person dictates circulating volume and, therefore, the concentration of the medication in the bloodstream. Delivering a dose based on weight answers this need to ensure the drug concentration—and therefore therapeutic threshold—is achieved. This is particularly true of medications that stimulate or inhibit receptors. When calculating a weight-based dose, remember to use the patient’s weight in kilograms, not pounds. The age of a patient plays a big role in how medications are absorbed in the body. Alterations in the fluid and fat percentages can change how much medication is needed. Metabolism at the extremes of ages also changes how much of a medication is available at any time and can slow elimination of a medication. Finally, paradoxical reactions also are more common at the extremes of ages; for example, particularly young people tend to get excited or agitated when sedatives are administered. Hypothermia has the effect of slowing metabolism. Therefore, medications are metabolized more slowly, meaning that medications that are typically repeated will need to be repeated less frequently. Also, because cellular metabolism is slower, the effect of the medication once it arrives at the site of action is slower to occur. Hyperthermia has the effect of accelerating metabolism, so, theoretically, the metabolism of a medication will be faster and the effect will be shorter in duration.
Pregnancy causes a host of changes in the mother that determine how medications affect the body. - Circulating blood volume increases along with cardiac output. - Hematocrit decreases because the circulating volume expands faster than the extra red cells can be produced. - Patients who are pregnant often are tachypneic because of both the reduced hematocrit and the reduced ability of the lungs to expand as the fetus grows larger in the later months of pregnancy. - Gastrointestinal motility decreases, whereas urinary output increases, which alters elimination patterns for medications. Pharmacokinetics Pharmacokinetics is the action of the body on a medication, specifically how a medication is absorbed, distributed, biotransformed, and eliminated. The onset of effect, and peak concentrations of the medication, are determined by how the medication is absorbed and distributed throughout the body. The duration of the medication’s effect is largely impacted by how much the body needs to do to the medication through biotransformation and how long it takes for the medication to be eliminated from the body. Some medications are not administered in the form that ultimately exerts the effect; in these cases, the medication needs to be biotransformed by the body’s existing enzymes before it can exert its therapeutic effect. The route of administration has the greatest impact on absorption, so selecting the best route of medication administration in the emergent situation is of paramount importance. Before the paramedic can administer any medication, he or she has a responsibility of ensuring that several items have thoroughly verified before going ahead and administering the medication. These are referred to as the 7 Rights of Medication Administration. Some texts and tests will refer to only 5 or 6 “rights,” often omitting the last 1 or 2 items. Remembering and verifying all 7 rights, however, is essential for the safe, appropriate administration of medication to patients. Seven Rights of Medication Administration
Routes of Administration For this section, there will be the type of route, for example, oral, followed by the acceptable abbreviation for administering medication via this route. This will then be followed with essential information about the route and any specific directions the paramedic must follow when using each method for medication administration. Finally, the section will conclude with medications in the paramedic’s repertoire that would be given that way. Enteral Enteral routes of administration use the digestive tract for absorption. Medications absorbed through the gut (stomach and intestines) are subject to first-pass metabolism. When a medication is absorbed through the digestive tract, it first enters hepatic circulation. During this first pass through the liver, a predictable amount of the medication is metabolized to a nontherapeutic form, which results in only a fraction of the medication available to the body for its therapeutic purpose. The amount of drug available for therapeutic effect is known as its bioavailability. Typically, medications administered sublingually or rectally, although still considered enteral routes, avoid first-pass metabolism.
Oral. Oral medications are the most commonly prescribed medications for patients to use at home. In the prehospital world, very few medications are administered via this route because many oral medications are subject to first-pass metabolism, which protracts the time to bioavailability and the onset of therapeutic effect. Oral administration often is the slowest administration to onset of action time. To administer anything via the oral route, the patient must be conscious, able to protect his or her own airway, and able to swallow. Ideally, the paramedic should be fairly certain that unconsciousness is not imminent. Baby aspirin, activated charcoal, and Insta-Glucose are given this way. - Wear gloves and ensure that the patient does not have any allergies to the medication about to be received. - Obtain medical direction for administration of the medication through either standing or online orders. - Verify the 7 rights of medication administration. - Ask the patient to lift his or her tongue to the roof of the mouth while keeping the mouth open wide. Demonstration goes a long way to success with this. - Deposit the tablet under the tongue or deliver 1 spray to that area. - Advise the patient that this may taste unusual and may even burn. Also advise the patient not to chew or swallow the tablet. - Monitor the patient and document the administration. Buccal. This is the space between the gum and the cheek, typically on the lower jaw. In the prehospital realm, paramedics can deliver glucose gel this way, although the patient usually swallows it. Follow these directions: - Wear gloves and ensure that the patient does not have any allergies to the medication about to be received. - Obtain medical direction for administration of the medication either through standing or online orders. - Verify the 7 rights of medication administration. - Deposit the medication between the cheek and the gum. Some paramedics find it helpful to place the medication on a tongue depressor first and then place the tongue depressor between the cheek and the gum. - Advise the patient to try not to chew or swallow the medication. - Monitor the patient and document the administration. Orogastric and Nasogastric Tubes. Paramedics do not commonly use these routes for medication administration; however, it is possible that one will be inserted during patient contact. These routes are ideal for administering activated charcoal, particularly in the patient who is obtunded. After confirming gastric placement as indicated), draw up the appropriate amount of medication into a syringe and administer it through the tube. Flush the tube with 30–60 mL of warmed saline or sterile water into the tube to ensure the medication has entered the stomach. Close and clamp the tube. - Wear gloves and ensure that the patient does not have any allergies to the medication about to be received. - Instruct the patient to relax and not bear down. - If using a suppository, lubricate it with a water-soluble gel and insert it into the rectum about 1 to 1.5 inches beyond the anal sphincter. - For medications that are liquid, draw them up into a syringe in the appropriate dose. - Attach a large-bore intravenous catheter to the end of the syringe. - Insert the catheter into the rectum about 1 to 1.5 inches beyond the anal sphincter and slowly depress the plunger, observing for any leakage of the fluid out. If this happens, insert the catheter deeper and continue. - Monitor the patient’s condition and document the administration. Parenteral, Invasive The following routes of administration are via the parenteral route, which means outside the digestive tract. Some are used frequently in emergency medical services (EMS), whereas others are rarely used and are indicated as such. Intradermal. This is rarely used by a paramedic and is most commonly used to administer purified protein derivative testing for tuberculosis (TB). In this procedure, a small amount of liquid medication is delivered in between the layers of the skin to form a wheal, a raised area with a pool of medication resembling a mosquito bite. The needle is typically a 25–27 gauge needle, and the volume of medication does not exceed 0.5 mL. The rate of absorption is extremely slow because of the lack of superficial vasculature in the areas used for injection, so this method does not lend itself well to the emergent administration of medications. - Wear gloves and ensure that the patient does not have any allergies to the medication about to be received. - Obtain medical direction for administration of the medication through either standing or online orders. - Verify the 7 rights of medication administration and collect the needed equipment to perform the skill: an alcohol swab and a 1–3 mL syringe with a 24–26 gauge needle to draw up the medication. - Subcutaneous injections often are given in the upper arm, buttocks, anterior thigh, or abdomen. Cleanse the selected spot with alcohol, starting in the center of the injection spot and clean from the inside out in concentric circles. - Pinch the skin around the cleansed area, advise the patient of the stick and possible discomfort in the area and insert the needle at approximately a 45° angle. - Inject the medication and remove the needle. You may rub the area after the injection to not only distribute the medication but also ease localized pain from the injection. - Immediately dispose of the needle in a sharps container without recapping. - Monitor the patient’s condition and document the administration. Intramuscular. This technique is highly similar to subcutaneous injections; however, the muscle can handle up to 5 mL of fluid at a time. Absorption rates are about the same for both subcutaneous and intramuscular injections. The deltoid muscle of the lateral shoulder, the vastus lateralis muscle of the lateral upper leg, the rectus femoris muscle of the anterior thigh, and the lateral superior area of the gluteus maximus muscle are ideal locations for intramuscular injections. It is important to stay in the lateral superior area of the gluteus maximus to avoid the even remote possibility of hitting the sciatic nerve in the medial areas of the buttocks. Follow these directions: - Wear gloves and ensure that the patient does not have any allergies to the medication about to be received. - Obtain medical direction for administration of the medication through either standing or online orders. - Verify the 7 rights of medication administration and collect the needed equipment to perform the skill: an alcohol swab and 1–5 mL syringe with a 20–24 gauge needle to draw up the medication. The needle should be at least 1 inch long to ensure entrance into the muscle and not remain in the subcutaneous space. - Cleanse the selected spot with alcohol, starting in the center of the injection spot and clean from the inside out in concentric circles. - Stretch the skin around the cleansed area to further minimize the amount of subcutaneous area between the skin and the muscle, advise the patient of the stick and possible discomfort in the area, and insert the needle at a 90° angle. - Aspirate (pull back on the needle plunger) and check for blood. If blood is present, abandon the site, discard the needle and syringe immediately into a sharps container, and prepare another syringe of medication. Blood means you may have inadvertently entered a blood vessel, which is not desirable in this method. - If you do not get anything back with aspiration, inject the medication and remove the needle. You may rub the area after the injection to not only distribute the medication but also ease localized pain from the injection, although this is not necessary. - Immediately dispose of the needle in a sharps container without recapping. - Monitor the patient’s condition and document the administration. Intravenous Bolus. When it comes to emergency medication administration, intravenous administration is the granddaddy of all methods. The intravenous route is the fastest of all routes at the paramedic’s disposal and is the most likely method for administering medications. Bolus means a single dose given all at once, versus intravenous piggyback or drip (discussed next), which is slower and given during an extended time frame. Follow these directions: - Wear gloves and ensure that the patient does not have any allergies to the medication about to be received. - Obtain medical direction for administration of the medication through either standing or online orders. - Verify the 7 rights of medication administration and collect the needed equipment to perform the skill: an alcohol swab and a 3–10 mL syringe with an 18–24 gauge needle to draw up the medication only. Most intravenous line medication ports no longer require needles to draw up the medication. - Verify that the established intravenous line is still patent by flushing it with approximately 10 mL of saline. Abandon the site if the line will no longer flush or you see bruising or infiltration around the intravenous site in the patient’s arm. - Cleanse the selected medication administration port with alcohol and attach the syringe to the medication port. - Pinch the tubing between the selected medication port and the bag to prevent the medication from flowing backward away from the patient and into the bag. - Inject the medication and disconnect the syringe from the medication port. Release the pinch on the tubing and allow the line to flow. - Dispose of the syringe in a sharps container immediately without recapping. - Monitor the patient and document the administration. Intravenous Piggyback. Occasionally, paramedics will be required to give a medication infusion that is a small dose of medication given for a period of time, usually to maintain therapeutic levels of a drug in the bloodstream. The medication is injected into a bag of intravenous solution that is then connected—piggybacked—to a maintenance line of normal saline or lactated Ringer solution instead of directly into the vein. Paramedics may initiate only 1 or 2 such piggybacked lines, but they may be required to monitor many more during complex interfacility transports. It is highly recommended to use a mechanical pump for administering these medications so that the precise amount of medication is delivered; under- or overdosing patients with these medications can have disastrous effects on a patient’s condition. Intraosseous. This route has absorption rates nearly identical to that of intravenous administration. Initiation of intraosseous lines is discussed later in this guide. Any medication that can be given intravenously can be given intraosseously. Fluid does not typically flow well through an intraosseous line and may require a pressure infusion, which can be achieved by taking a blood pressure cuff and inflating it until the desired drip rate is achieved. Occasionally, the pressure may need to be increased as fluid drains from the bag. Pressure infusion bags are available and achieve the same result. Follow these directions: - Wear gloves and ensure that the patient does not have any allergies to the medication about to be received. - Obtain medical direction for administration of the medication through either standing or online orders. - Verify the 7 rights of medication administration and collect the needed equipment to perform the skill: an alcohol swab and a 3–10 mL syringe with an 18–24 gauge needle to draw up the medication. Most intravenous line medication ports no longer require needles to draw up the medication. - Verify that the established intraosseous line is still patent by flushing it with approximately 10 mL of saline. Abandon the site if the line will no longer flush or you see bruising or infiltration around the intraosseous site. - Cleanse the selected medication administration port with alcohol and attach the syringe to the medication port. - Pinch the tubing between the selected medication port and the bag to prevent the medication from flowing backward away from the patient and into the bag. - Inject the medication and disconnect the syringe from the medication port. Release the pinch on the tubing and allow the line to flow. - Dispose of the syringe in a sharps container immediately without recapping. - Monitor the patient’s condition and document the administration. Parenteral, Noninvasive The following routes of medication administration are still parenteral but are noninvasive. Transdermal. With this route, medications are absorbed into the bloodstream after passing through the skin. The medication must be fat soluble and small enough to pass through the skin. This route acts similarly to an intravenous piggyback, where the medication is delivered slowly across time and at the same rate. Follow these directions: - Wear gloves and ensure that the patient does not have any allergies to the medication about to be received. - Obtain medical direction for administration of the medication through either standing or online orders. - Verify the 7 rights of medication administration. - Cleanse the selected spot with alcohol, starting in the center of the injection spot and cleaning from the inside out in concentric circles. Dry the area thoroughly. - If the medication is a cream in a tube, apply the appropriate amount to the application paper and apply to the skin. If it is a premedicated patch, peel the patch from the backing and then apply to the skin. - Monitor the patient’s condition and document the medication administration. Inhalation. The inhalation route has several methods of delivery; in guide 3, information about O2 delivery devices is given. Patients will have metered dose inhalers (MDIs) for beta-agonists such as albuterol and other medications that exert their effects when breathed into the bronchial tree. Paramedics and EMTs can help their patients administer inhaled beta-agonists from MDIs. Follow these directions: - Wear gloves and obtain medical direction for administration of the medication through either standing or online orders. Because it is the patient’s MDI, you already know that the patient does not have an allergy to the medication. - Verify the 7 rights of medication administration, paying particular attention to whether the patient has taken any medication recently within the prescriber’s window, usually within the past 5–10 minutes. - Shake the canister and have the patient exhale completely. - Have the patient put his or her lips around the opening of the canister. As the patient begins to inhale, have the patient squeeze the plunger. If the patient uses a spacer, have the patient continue to use it. - Direct the patient to hold his or her breath as long as is comfortable before exhaling. - After a couple of breaths, repeat the process until the prescribed dose is completely given. That is, if the prescription says to take 2 puffs every 5 minutes, you can administer a 2nd puff right away. Remember, it is only 1 squeeze of the canister per breath. - Monitor the patient’s condition and document the administration. Inhaled medication also may be given via nebulizer, as follows: - Wear gloves and ensure that the patient does not have any allergies to the medication about to be received. - Obtain medical direction for administration of the medication through either standing or online orders. - Verify the 7 rights of medication administration and collect the needed equipment to perform the skill: a nebulizer kit and an inhaled bronchodilator. - Add the medication to the chamber of the nebulizer without the O2 connected to it. - Assemble the nebulizer. - Connect the O2 tubing and start the flow of O2 at between 6 and 10 L per minute to produce a fine mist. - Have the patient securely hold the mouthpiece in his or her mouth. - Coach the patient to take deep breaths and hold his or her breath as long as comfortable before exhaling each time to give the medication a chance to work. Tap the sides of the chamber occasionally to knock down condensate on the sides of the chamber. Continue until no fluid remains in the chamber of the nebulizer and no mist is produced. - Monitor the patient throughout administration and watch for side effects. Advise the patient that he or she will possibly feel jittery during the treatment. Tip: If the patient is unable to hold the mouthpiece in his or her mouth or is unable to hold the nebulizer with his or her hand, you can remove the bag from the mask of a non-rebreather and insert the chamber of the nebulizer into the hole where the bag came out. Just ensure that the chamber remains upright so that the medication can be nebulized and does not spill. In other words, this route of administration cannot be done in a patient who must remain supine. - Wear gloves and ensure that the patient does not have any allergies to the medication about to be received. - Obtain medical direction for administration of the medication through either standing or online orders. - Verify the 7 rights of medication administration. - Draw up the appropriate dose of the medication in a syringe, generally 2–2.5 times the usual intravenous dose of the medication. - Attach the mucosal atomization device to the syringe. - Spray half the volume into each nostril. - Immediately discard the syringe and mucosal atomization device into the sharps container. - Monitor the patient’s condition and document the administration. - Wear gloves and ensure that the patient does not have any allergies to the medication about to be received. - Obtain medical direction for administration of the medication through either standing or online orders. - Verify the 7 rights of medication administration. - Deliver the medication, usually double the intravenous dose, into the ETT and ventilate the patient briskly to deliver the medication out of the tube and into the bronchial tree. How Medications Are Supplied Medication packaging varies depending on the stability of the medication and the method in which it will be given to a patient. The 3 types of medication packages are ampules, vials, and prefilled syringes. Ampules are sealed glass containers that contain a sterile solution of medication and typically contain a single dose of medication. Epinephrine 1:1,000 dilution often comes packaged this way. To extract the medication, follow these steps: - Flick the ampule with your finger to get all the fluid into the bottom section. - Grip the ampule by the top between your thumb and forefinger on your dominant hand and the bottom in the fist of your other hand and break the top off at the narrowed neck. - Insert a filter needle into the bottom portion and draw up the medication. It is important to use a filter needle whenever possible in case some small glass shards fall into the medication. Immediately discard the ampule in the sharps container. - With the needle pointed upward, tap the barrel of the syringe to get air in the fluid to bubble up to the top. Expel the air from the syringe, remove the needle, and place the needle into the sharps container. - The syringe is now ready to attach to an intravenous medication port. Alternatively, you can attach another needle for administration via the intramuscular or subcutaneous route. Vials are more common than ampules and are easier to use. Vials are glass or plastic bottles with a rubber stopper that is covered with a plastic breakaway cap. They may contain single or multiple doses of a medication. Many medications come in a ready-to-use solution; however, some may need to be reconstituted. To reconstitute a medication, press the top of the vial down; the center stopper that separates the liquid from the solid pellet in the bottom will dislodge, allowing the liquid and solid to mix. Shake until completely dissolved and use promptly. Follow these steps to withdraw the medication from the vial: - Remove the cover and wipe the rubber stopper with an alcohol swab. - Draw up air into a syringe with a needle attached equal to or slightly more than the volume of fluid you will need from the vial for the dose. - Insert the needle through the center of the stopper (the edges are much thicker) and inject the air into the vial. - Invert the vial. With the tip of the needle below the level of the liquid, allow the pressure of the air that was just injected to force the liquid into the syringe. Draw up the remaining fluid to slightly more than what you would need for the dose. - Remove the needle from the vial and then from the syringe (unless being used as an intramuscular or subcutaneous injection) and discard immediately. The syringe is now ready to be connected to a medication port on the intravenous line. Prefilled syringes are ready-to-use syringes that come with a set amount of medication already in a needleless system. Simply screw the plunger piece into the barrel containing the fluid, connect to the medication port on an intravenous line, and deliver the appropriate amount to the patient. Remember, not all the medication in a prefilled syringe may be needed as a single bolus, so be sure to know the dose before connecting. Distribution of Medication The 2nd component of pharmacokinetics is the distribution of medication after it has been absorbed into the bloodstream. Distribution involves getting not only the drug to the cells in which it will exert its effects but also the medication into the cells as needed. Several methods are available for this. Medications that attach to receptors do not need to enter the cell, necessarily, but they frequently do need to leave the bloodstream to get to the receptors. Small molecules that are nonionic, or uncharged, and molecules that are lipophilic, which means fat loving or fat soluble (and therefore hydrophobic or water hating), can pass through cells with relative ease and can easily cross cell membranes to do so. Larger molecules and molecules that are hydrophilic, which means water loving (and therefore fat hating) have a harder time crossing the cellular barrier. Once inside, the molecule can move about freely; it is just crossing the membrane that presents the issue. These types of molecules need help, which can happen in any of 3 ways. Pinocytosis is where the cell buds small vesicles to bring it inside. The 2nd way is through facilitated diffusion, where proteins that stretch from side to side in the membrane provide a pathway for the molecule to enter. Finally, active transport requires the use of cellular energy to move the molecule across the membrane. Biotransformation Most of the medications prescribed require some form of metabolism once in the body, a process called biotransformation. From this process, either active or inactive metabolites are formed. Active metabolites can be the active form of a drug, which is the one that actually exerts its effects on the body. Active metabolites also are an active form if they are harmful to the body. Active just means it is actually doing something in the body. Inactive metabolites are exactly that: inactive—essentially waste. Finally, biotransformation also may play a role in converting a substance to another metabolite that is easier for the body to eliminate. - The cytochrome P-450 system in the liver is the site of most biotransformation. - Medications taken orally often are biotransformed by bacteria in the gut. - The kidneys, skin, and the lungs also have the ability to biotransform medications, typically for elimination. Medication Elimination Medications that are absorbed after being taken orally most often are removed from the body by the kidneys. Some oral medications never even see the bloodstream and are eliminated in their original form in solid waste. The 2 distinct ways in which the medication gets removed are zero-order elimination and first-order elimination. Half-Life Calculations
Intravenous Therapy One of the most common procedures a paramedic will perform is the initiation of intravenous therapy. Frequently, establishing an intravenous line is done primarily as a route of access for medication administration. Other times, it will provide fluid resuscitation for the patient who is at risk of developing shock. Fluids The body, as seen in guide 1, is in a very delicate state of balance. Although the body has many compensatory mechanisms to maintain that state of balance, a very important mechanism the body has to work through is the salt balance. If sodium and potassium ions exchange places for too long, death can result. Potassium needs to stay inside the cells, and sodium needs to remain outside the cells. Water follows sodium, so if the body does a poor job at removing excess sodium, fluid overload can result, putting an excess workload on the heart. When fluid is administered, some stays in the vasculature, some moves into the intercellular fluid, and some moves into the cells, all based on where these ions, or solutes, are located. Solute is that which is dissolved and can refer to sugars or salts. A solvent is the item, frequently water, into which something dissolves. The body has an overall solute concentration within the cells of approximately 0.9%, which is about 9 g of solute in about 1,000 mL of fluid. Most fluids that are administered are isotonic, which means that they have approximately the same solute concentration as the plasma and intercellular fluid. These fluids include 0.9% saline solution, referred to as normal saline solution (NSS). NSS is the most commonly used prehospital fluid because it is designed to be harmonious with the body’s natural salt balance. Lactated Ringer solution also is isotonic, resulting in no net movement of water into or out of the cells. Figure: Water moves from areas of low-solute (high-water) concentration to high-solute (low-water) concentration. Establishing an Intravenous Line Before even preparing to break skin, select the intravenous solution. Most prehospital providers prefer to go with the saline lock and flush, unless the patient is dehydrated, in shock, or bleeding and a fluid bolus is needed. The saline lock and flush provides the necessary access for potential medication administration without being cumbersome or making extrication more difficult, such as an intravenous line and bag can. To establish an intravenous fluid drip, NSS is most common, although lactated Ringer solution is the optimal choice in trauma. When selecting the fluid, ensure that the fluid is clear and not expired. Equally important is choosing which administration set to use. Generally speaking, administration sets come in microdrip or macrodrip setups. The microdrip setup forms smaller droplets than the macrodrip setup, thus allowing finer control of fluid administration, which is essential in fluid-overloaded patients. The microdrip setup also is the administration set of choice for most medication infusion drips. The microdrip takes 60 drops (gtt) to make 1 mL, which is written 60 gtt/mL. The macrodrip administration set is used in all other situations, especially when large volumes of fluids may need to be given, such as in cases of bleeding, dehydration, and burns. Macrodrips typically can deliver 10 gtt/mL or 15 gtt/mL and are occasionally used for medication infusions. It has been decided that the patient needs an intravenous line, and the fluid has been chosen and prepped. Where should the line be established? Some options are better than others, and certain things are worth considering. First, try to find the straightest, biggest vein; even if it is not necessary, start the largest bore intravenous line possible. The vein will be spongy or springy when palpated, which will enhance the chances of success. From a patient’s perspective, the least painful spot in which to start an intravenous line is the anterior forearm; the dorsum of the hand and antecubital area can be the most painful, though they usually harbor the finest veins. The anterior wrist just proximal to the palm of the hand should be avoided despite tempting veins because this is the most sensitive area of the arm. Paramedics also can use the external jugular (EJ) vein as an intravenous insertion site on either side of the neck, but this location is preferable only in patients who are unconscious or in extremely dire circumstances. Some guiding principles for intravenous establishment include starting distally and working proximally to minimize the chances of proximal missed intravenous site infiltrate, or bleeding into the soft tissue surrounding them, when the intravenous line is run. Next, pull traction on the selected site to anchor the vein in place, which can be done by either pulling the skin of the hand distally and over the first knuckle or stretching the skin away from the vein.
To cannulate the vein found on the lateral wrist, flex the wrist medially to anchor it. For the EJ vein, when a cervical spine injury is not suspected, push the head to the side opposite the side selected for cannulation; this will provide most of the anchoring. Select the intravenous catheter that represents the purpose for establishing the intravenous line. For example, if the primary purpose of the access is to provide a medication route, then a 20-gauge catheter should be sufficient. If the line could potentially be used to administer blood or blood products in the hospital, it is recommended to start with an 18-gauge line or larger. Finally, for aggressive fluid resuscitation in trauma and burns, a 16-gauge or larger line should be initiated. Of course, all these options are determined by the size of the optimal vein; not all veins will accept what the patient really needs. Perhaps a patient’s vein will take only a 22- or 24-gauge catheter. In such cases, establishing a patent intravenous line of any size is first and foremost. At this point, all the necessary decisions that need to be made have been made regarding the intravenous site, the fluid type, and catheter size. Now it is time to actually perform the procedure. Nothing is more important when performing any procedure than gathering all the equipment you could possibly need, which includes preparing for success as well as failure. Some intravenous start kits come complete with everything needed for either case in one neat little package, but this equipment should be on a mental checklist.
Have the following items within arm’s reach before inserting the needle through the skin: - The intravenous catheter, appropriately sized for the patient’s needs and vein size - The intravenous administration set with fluid completely run through or a primed saline lock - Tape, at least 3 strips torn into 3–4-inch lengths and the roll nearby When all the supplies are present, insert the catheter. The following steps will guide successful placement: - Place the tourniquet on the upper arm tight enough to occlude the veins but not hamper arterial blood flow. Although it should go without saying, if using the EJ vein, do not put a tourniquet around the neck. As noted earlier, tape for securing the line (or gauze if the site needs to be abandoned) should be torn and within arm’s reach. - Next, palpate the vein that is suitable for the purpose. Ensure you know the relative pathway of the vein. - Cleanse the site, starting from the point you anticipate inserting the catheter and working in concentric circles outward. Allow to air dry or dry with a sterile gauze pad. Do not palpate the vein in this area again without cleansing the area again. Tip: Sometimes, if you know a vein cannot be anchored, that is, it rolls around under the skin, it is helpful to start alongside the vein and then redirect the needle into the vein from the side rather than from the top. Because the vein rolls, the needle will push the vein until it cannot roll any further and invariably enter the lumen of the vein. You also can use this technique if you know it will be painful for the patient. This technique will allow you to enter the skin faster without puncturing the vein right away. Because this is the most painful part of the procedure, take your time to cannulate the vein. Complications Although starting an intravenous line is perhaps the most routine, innocuous procedure that paramedics perform, it is not free of complications, some of which are potentially lethal, that need to be weighed when contemplating the potential benefit of starting the line. Although it is possible to tell the difference between a vein and tendon, ligament, and nerve structures simply by palpating, occasionally the sight or feel for the vein is lost and one of these structures is hit. If one of these structures is hit with the needle, remove the needle and catheter and try again elsewhere, after profusely apologizing to the patient. Occasionally, particularly in the area of the antecubital fossa where the vein and artery are very close, an artery rather the vein can be punctured. After arterial puncture, it is possible for the line to flow normally in these cases; however, sometimes the blood pressure is high enough that blood starts pulsing up the line. If an artery is struck, abandon the site and apply direct pressure to the site for at least 5 minutes; a longer period of direct pressure is requires for patients who are anticoagulated. Occasionally, even bags without leaks become contaminated, yet still appear clear. This contamination is then injected into the patient, causing pyrogenic reactions and generating a high fever usually within 30 minutes of the initiation of the intravenous line. Such reactions will then rapidly progress to what is essentially septic shock with hypotension, tachycardia, and an altered mental status with an extremely high fever. Stop the infusion and remove that intravenous line. Establish another line and treat the patient for the resulting shock, in addition to what the patient had beforehand that initially necessitated the intravenous line. Thrombophlebitis is inflammation of the vein that was catheterized and is strongly related to poor aseptic technique. Irritating medications or infusions also can be a cause. If redness develops at the insertion site or the patient complains of pain and itching along the route of the vein, stop any infusion and discontinue the intravenous line. Warm compresses will help reduce the pain. An air embolus results from the introduction of large amounts of air directly into the vein. Properly flushing an intravenous line prior to initiation will prevent this issue. Intraosseous Therapy If you are unable to start an intravenous line or if the patient is in cardiac arrest, initiating an intraosseous line is a suitable alternative. Although this has been done for decades in children, it become an option for adults only within the last decade. Intraosseous lines are quick to establish and provide for administration-to-clinical-effect times for all medications that are similar to those for intravenous administration. The needle is driven through the outer compact bone and into the highly vascular marrow. The intraosseous line should not be started in cases of tibial fracture or if there are burns or a skin infection, such as cellulitis, overlying the site of entry. An intraosseous line can be started in any patient who would otherwise get an intravenous shot and is in a critical, life-threatening situation.
Contraindications to initiating an intraosseous administration include the following: - Osteoporosis - Osteogenesis imperfecta, a genetic condition in which bone does not form properly - Fracture in the same extremity into which the intraosseous needle would be placed - Previous attempts in the same bone - Infection or burn over the insertion site - Cleanse the site, starting at the point you anticipate inserting the needle and working in concentric circles outward. Allow to air dry or dry with a sterile gauze pad. Do not palpate the vein in this area again without cleansing the area again. - Attach the needle to the driver. - Insert the needle at a 90° angle to and through the skin directly against the bone without activating the driver. Once against the bone, turn on the driver by squeezing fully on the trigger and applying very gentle pressure, letting the spinning needle do the work.- - - - Secure with a commercial stabilizing device from the manufacturer, or similar to any impaled object, with bulky dressings around the needle and a lot of tape or roller gauze. Complications to intraosseous therapy are much less likely than with intravenous therapy. Aside from pain being reported only during the infusion, and rarely during the actual insertion, the biggest complication of intraosseous insertion is infiltration. If the site is infiltrating and the infusion is not stopped, compartment syndrome can occur, leading to necrosis (death) of muscle and tissues surrounding the bone. Particularly in small or fragile bones, such as those found in osteogenesis imperfecta or osteoporosis, fracture is a possibility. An extremely rare complication is osteomyelitis, which is inflammation of the bone and muscle surrounding it caused by infection. To prevent osteomyelitis, avoid any area of skin that appears red or inflamed near or over the insertion site.
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