Principles of Medication Administration (Clinical Essentials) (Paramedic Care) Part 3

Weight-Dependent Intravenous Drug Infusion

Some drugs are so potent that it is important to precisely infuse (i.e., titrate) the drug to the patient’s weight. As complicated as the process sounds, a weight-dependent intravenous drug infusion only adds the patient’s weight to the standard drug infusion calculations (Table 26-9).

Table 26-8 Calculation of Intravenous Drug Infusion Rate Using the Clock Method

Order = 3 mg per minute (3 mg/min)

Administration set = 60 drops per mL

Solution on-hand = 250 mL physiologic saline

Drug on-hand = 1 gram

Drip rate = X

Step 1: Calculate the concentration

1 gram in 250 mL = 2 milligrams per 1 milliliter

1,000 gram/250 mL = 2 mg/mL

(Conversion to common units makes calculations easier)

Step 2: Step up the clock

1 mg = 15 drops per min = 30 mL/hour

2 mg = 30 gtt/min = 30 mL/hr

3 mg = 45 gtt/min = 45 mL/hr

4 mg = 60 gtt/min = 60 mL/hr

Table 26-9 Weight Dependent Drug Infusion

Order = 5 microgram per kilogram per minute (5 mcg/kg/min)


Administration set = 60 drops per mL

Solution on-hand = 500 mL physiologic saline

Drug on-hand = 1 gram

Drip rate = X

Patient weight = 70 kg

Formula = Order X Solution X Patient’s weight (kilograms) X Drip rate of administration set Concentration of the drug

Step One: Calculate the concentration

1 gram in 500 mL = 2 milligrams per 1 milliliter

1,000 gram/500 mL = 2 mg/mL = 2,000 mcg/mL

Step Two: Set up the formula

Order X Drip factor X Patient weight Drug concentration


5 mcg/kg/min X 60 gtt/mL X 70 kg/2,000 mcg/mL = X

Step Three: Eliminate like units

5 X 60 gtt X 70 min/2,000 = X

25,000 gtt/min/2,000 = X

10.5 gtt/min = X

The Paramedic’s failure to convert a patient’s weight from pounds (household common) to kilograms (metric) is a source of error in some calculations. It is essential that all Paramedics convert all units to a common system before performing drug calculations.

Temperature Measurement

A patient’s body temperature has come to be regarded as a key indicator of a patient’s health or illness (i.e., a vital sign). A fever greater than 101°F, might indicate the presence of an infectious process inside a patient’s body or that the patient’s body has undergone a significant heat stress. A fever greater than 100.4°F but less than 101°F, may indicate an inflammatory response. Regardless of the source of a patient’s elevated (or depressed) temperature, the body can only tolerate a very narrow range of temperature change from its baseline and still function. Core temperatures above or below this range can lead to cessation of essential metabolic processes and chemical reactions critical to all organ function. Understanding the importance of body temperature as a vital sign, Paramedics often obtain a temperature using a red-dyed alcohol thermometer or, more recently, a tympanic membrane thermometer.

While Galileo Galilei invented the water thermometer in 1593, then called a thermoscope, the invention of the first accurate and functional mercury thermometer was attributed to a meteorologist named Daniel Gabriel Fahrenheit in 1714. Using a water and salt solution as a standard, he established a freezing point for the solution, at 0°F, then established the freezing of water alone (30°F) and temperature of the human body (90°F). These values (later adjusted to 32°F and 98.6°F, respectively), when obtained by thermometer, established a rapid and objective means of assessing a person’s body temperature.

Shortly after establishing the Fahrenheit scale, Anders Celsius, a Swedish astronomer, replaced the previously used salt solution with pure water and again froze and then boiled the pure water at sea level (standard atmospheric pressure). Using these measurements as a baseline, he evenly divided the difference into 100 increments, or a centigrade scale, with zero being frozen water and 100 being boiling water. This centigrade scale, also called the Celsius scale, was adopted by an international conference on weights and measures, held in 1948, as the official temperature scale.

Analogous to the duality of household common and metric measurement systems, the public (particularly in English-speaking countries) adopted the Fahrenheit scale whereas the scientific community adopted the Celsius scale.

While many thermometers produced have both Celsius and Fahrenheit scales imprinted on the glass cylinder, in some instances a Paramedic may be asked to convert Fahrenheit to Celsius or vice versa. The most apparent difference between these two scales is that one is based upon 180 even divisions between freezing and boiling, whereas the other is based upon 100 even divisions. Therefore, any conversions will necessarily involve a 9/5 or a 5/9 adjustment to make the scales equal.

Similarly, the Fahrenheit scale does not have water freezing at zero degrees but at 32 degrees. Therefore, to balance the two scales 32 must be either added or subtracted from the result. To convert Fahrenheit to Celsius (medical standard temperature measurement) the EMS provider must first subtract 32 from the number and then multiply the Fahrenheit temperature by 5/9. For example, for a temperature of 103°F, subtract 32 and multiply the result by 5/9 to get the temperature on the Celsius scale—(103 — 32) 5/9 = (71)5/9 = 39.4°C. The opposite would be true to convert Celsius to Fahrenheit.

Administration of Medication

The administration of medications may be one of the greatest responsibilities that a Paramedic has to perform. Because of the nature of a medical emergency, Paramedics are permitted to administer powerful and potentially lethal drugs. When given correctly, these medications can help to improve a patient’s condition or relieve some suffering. Given incorrectly, the Paramedic may make a bad situation worse. Therefore, Paramedics are ever mindful of their responsibilities whenever drugs are being administered. Like nurses, Paramedics practice the five rights of medication administration (right person, medication, dose, route, and time). The five rights simply represent an intelligence, a way of thinking, that decreases the potential for medication errors.

The first right refers to the right patient. Although this is an infrequent request, the Paramedic may be asked to assist in giving medications to patients with whom he is not familiar, such as during a mass casualty incident, while practicing in an expanded role, or while acting within an emergency department as part of the staff. In those instances, the Paramedic would be expected to identify the patient. If the patient is awake, alert, and able to communicate, then a personal identification may be attempted. If the patient is part of a system where personal identification, usually in the form of an identification band, is provided, then the Paramedic may check the band to verify the patient’s identity as well as identify the patient personally.

The remaining rights refer to the actual administration of the medication. At the beginning, the Paramedic will check to be sure that the right medication is being given. Generic medications can have names that either sound alike or are spelled similarly. Careful attention to detail, such as the spelling in the order and the spelling on the medicine container, will prevent a medication error.

It is good practice to verify a medication’s name when it is obtained from stock (whether that is a drug box or medicine cart), when it is being measured, and then finally when it is being administered. This triple check of the medication’s identity is expanded to include verification of the drug’s expiration as well as the clarity of the medication in the container. If there is any suspicion of potential contamination, then the drug should be immediately and safely discarded and a new supply of the drug obtained from stock.

As a drug is being prepared for administration, the Paramedic should be attentive to the next right, the right dose. While measuring a dose of medicine, the Paramedic may be at greatest risk of committing an error.

As previously mentioned, most emergency drugs are prepared so that one prefilled ampoule will be the correct dose for the average 70-kg patient. Unfortunately, patients do not always weigh 70 kg, so adjustments must be made. Furthermore, almost all pediatric medications, a large number of medications for the elderly, and an ever-increasing number of adult medications require weight specific dosing.

Calculating a weight-dependent dose, described earlier in this topic, is often difficult in the out-of-hospital setting. Poor lighting as well as patient urgency can lead to unintended errors. The creation of drug charts and use of personal digital assistants (PDA) have helped alleviate some of the difficulty of calculating the correct dose. Nevertheless, responsible Paramedics typically confirm—and then re-confirm—a drug calculation with another Paramedic. If another provider is not immediately available, then communication with the hospital emergency department is advocated. A colleague, such as a registered nurse or physician’s assistant, seated in a well-lit room with abundant resources at hand (including a calculator) can offer reassurance to a Paramedic who is alone calculating a critical medication dose.

STREET SMART

To decrease confusion and errors, medication orders of fractions of a whole are documented as 0.X instead of .X (e.g., 0.5 instead of .5). When given orally, they are said as "zero point X." By adhering to this practice, when an order for a one-half milligram dose of a drug is heard, it will not be mistaken for 5 milligrams of the drug. Similarly, whole numbers are listed as the digit (i.e., 1 is 1, not 1.0) and thereby prevent the accidental administration of 10 mg of a drug.

The next right, the right route, may seem at first blush to be obvious, as Paramedics usually administer drugs intravenously. Even when a drug is given intravenously, however, if the drug is not followed by a bolus to clear it from the intravenous administration set, or external chest compressions are not performed to circulate the drug, then the drug will not get to the target organ. In other instances, medications administered subcutaneously to a hypoperfused patient will not be absorbed and the patient will not benefit from the medication. The Paramedic should give heed to the warning (right route) and consider the method of which he is about to administer a medication in terms of its efficiency and effectiveness.

The final right, the right time, speaks to the administration of drugs on a repetitive schedule. At first blush, this might seem inapplicable to EMS. However, some drugs are given repeatedly in the field in order to obtain and maintain a certain therapeutic effect. For example, epinephrine is usually repeated every three to five minutes during a cardiac arrest until there is a return of spontaneous circulation (ROSC).12-14 In other situations, medications need to be given in a specific order (i.e., at the right time). For example, during a cardiac arrest, vasopressin or epinephrine always precedes an antidysrhythmic and paralytic drugs follow pre-induction medications.

After being given a drug, the patient is re-evaluated to see if the drug was effective. No exceptions should be made. Even the benefit of a seemingly innocent drug such as oxygen must be followed up with a re-evaluation of the patient’s condition. This re-evaluation, and subsequent documentation of patient response to medication, is so important that some Paramedics refer to it as the sixth right, the right documentation.

The initials DARE, a simple mnemonic, can help Paramedics remember the elements of documentation for every medication administration. First, what was the data (D) that was obtained and what action (A) was taken in response to that data? The documentation of the action, if it was a medication administration, should include the drug’s name, the exact dose of the drug, and the administration route, as well as the time of administration. After an appropriate interval, usually determined by the drug’s onset of action and peak effect, the patient’s response (R) to the drugs is assessed, both subjective and objective information obtained, and an evaluation (E) of the efficiency made. In some instances, the drug may be effective and further treatment is not indicated, while in other cases the drug has to be repeated.

Medication Routes

Practical necessity generally determines the route that a medication is given. If time is of the essence and it is important to get a precise dose to a target organ, without risk of first pass metabolism, then the intravenous route is preferred. If a local effect (e.g., skin preparation for a large bore intravenous needle) is needed, then a topically applied cream or subcutaneous injection would be appropriate. Each medication route offers specific advantages as well as disadvantages over other medication routes. Therefore, the route of medication administration is chosen with an express advantage or specific purpose in mind.

Preparation for Medication Administration

Regardless of the route of medication administration, whether it is a local route or a systemic route, the Paramedic must prepare both the patient and himself. The patient has the right to know what is being done and what medications are being given. A review of the discussion on informed consent is advised if the Paramedic is unsure of whether—and under what conditions—a patient can give informed consent.

The process of obtaining an informed consent from a competent patient can be summarized by the mnemonic AIR. First, the Paramedic must ask the patient if he has any allergies (A), particularly to the medication that is to be given. Then the patient should be advised of the intended (I) effect of the medication. Finally, the patient must be advised of reasonable (R) risks associated with the procedure and the medication. After obtaining the patient’s consent, the Paramedic should practice medical asepsis, including hand washing and donning gloves.

STREET SMART

When asking about allergies, the Paramedic should specifically ask the patient about allergies to latex, since a significant number of patients with chronic medical illnesses or healthcare workers have developed an allergy to latex. The Paramedic may find it difficult to differentiate whether the patient’s allergic symptoms were from the medication itself or the latex within products used to administer that medication. If the patient advises the Paramedic that he is latex-sensitive/allergic, then non-latex products must be used during care. Manufacturers are increasingly removing latex from their products for this reason.

Local Routes

Local routes of medication administration are intended to target a specific organ or function and confine the effects of the medication used to that area. For example, medications topically applied to the eyes are called optic medications. Paramedics occasionally apply a local anesthetic (e.g., pilocaine) to the eyeball to anesthetize it in preparation for irrigation. The eye is an important sense organ and administration errors can lead to blindness. Strict adherence to medical asepsis can decrease the potential for this complication.

When a medication is an ointment or gel, then a ribbon of the medicine is placed along the inside of the lower lid. To gain access to the inside of the lower lid, the Paramedic should first withdraw the eyelid from the eyeball and then roll the eyelid over a cotton swab, inverting the eyelid in the process. The ribbon of medication should then be applied from the inner canthus, proximal to the bridge of the nose, outward.

To avoid the risk of cross-contamination and infection, optic drops, ointments, and disks are single-patient use only. After use, the medication should be immediately discarded to avoid any opportunity for re-use.

Otic Medication

Medications applied into the ear are called otic medications. While it is rare for a Paramedic to instill medications into a patient’s ear, if the occasion should arise the patient should be instructed to tilt the head so that the affected ear is facing upward. After the correct volume of medicine has been drawn into the medicine dropper, the Paramedic would approach the patient. With the ear canal exposed and no visible drainage or obstruction noted, the Paramedic would place the dorsum of the dominant hand on the patient’s temple with the ear dropper firmly held in the hand and poised over the ear opening. This position prevents the ear dropper from being inadvertently dropped into the patient’s ear if the patient should startle and jerk. Grasping the pinna of the ear with the nondominant hand and pulling upward and outward, the medicine can be safely instilled into the ear. If the patient is incapable of cooperating with care, then consider placing the patient in the lateral recumbent position. If drainage is desired afterward, simply have the patient roll over to the opposite side.

Local Nasal Medication

The inner mucosa of the nostrils has a rich capillary bed that is an excellent route for the administration of systemic medications, discussed later in this topic. However, this same quality also makes the nose prone to bleeding (a nosebleed is called an epistaxis).

Epistaxis is an all-too-common event whenever a nasal pha-ryngeal airway or an endotracheal tube is introduced into the nostril. Subsequent bleeding can drain back into the hypophar-ynx and into the stomach, inducing nausea and possible regurgi-tation. To decrease the incidence of epistaxis, many Paramedics prepare the nostril with a topically applied vasoconstrictor, such as phenylephrine (Neosynephrine®). Placing the tip of an atomizer into the intended nostril, the atomizer bulb is given one or two squeezes, propelling the medicine against the mucosa.

Following this application of a local vasoconstrictor, some Paramedics lubricate the patient’s nares with a topical anesthetic, such as lidocaine gel. Using a nasal pharyngeal airway as an introducer, the Paramedic would liberally coat the airway and then insert the airway as usual. It is important that the Paramedic ascertain if the patient has any allergies to these medications before use. Alternatively, a water-based gel can be used to lubricate the nare. Under no conditions should a petroleum-based gel, such as Vaseline®, be used to lubricate the nostril prior to introduction of the airway device.

Phenylephrine and epinephrine (1:10,000) are also used in the treatment of severe epistaxis prior to packing. Approximately 90% of nosebleeds are anterior nosebleeds. Topical application of these potent vasoconstrictors provides local vasoconstriction that helps to decrease bleeding.

Local Oral Medications

Like the nose, the mouth has a capillary-rich mucosa that will rapidly absorb any medicine and distribute it systemi-cally. Systemic medications are typically placed in the buccal pocket of the cheek or underneath the tongue in the sublingual space. This route of medication administration is discussed in further detail later in the topic. However, the implication is clear. Large doses of topical oral medication can have a systemic effect and the patient should always be monitored carefully for untoward effects.

Various forms of topical oral medications are available. Gargles, such as a salt-water gargle, can be used to cleanse the mouth of contaminations, such as a blood splash, as well as dilute any potential pathogens. Hard lozenges and troches are designed to dissolve in the mouth, extending the duration of contact that the medicine has with the mucosa, perhaps to sooth ulceration.

Topical Medications

While a variety of options are used to apply medicine to the skin, such as liniments and lotions, and for a wide variety of purposes, from muscle aches to sunburn, Paramedics typically do not apply many topical medications. The exception may be the application of a topical antibiotic at the insertion site of an intravenous catheter.

Other Local Routes

For completeness, both douches and enemas should be mentioned. Paramedics rarely perform either of these procedures unless they are acting in an extended role. Both douches (solutions introduced into the vagina via an apparatus) and enemas (solutions similarly introduced into the anus via an apparatus) instill these solutions into those body cavities. Adding a medication to these solutions can provide a local therapeutic effect, such as when treating a yeast infection.

Routes for Systemic Medications

Medications can have a local effect or they can have a systemic effect (i.e., an impact on more than one internal organ system). Medications that are intended to have a systemic effect may be given via the gastrointestinal tract or via an injection. The first route, also referred to as the enteral route, is more common and includes taking oral medications, in the form of pills, as well as suppositories. The second route bypasses the gastrointestinal system and is called the parenteral route. The parenteral route is preferred during an emergency because of the rapidity of onset of the medication’s action as well as predictability of the drug levels.

The next section reviews the enteral route of drug administration, from head to toe, followed by a discussion of the parenteral routes of medication administration by inhalation and injection.

Enteral Drug Administration Sublingual Route

The first enteral route to be discussed is the sublingual route. The lingual space is an area inferior to the tongue. The floor of the sublingual space has abundant capillaries which can rapidly absorb medications. It drains into the lingual vein and then into the systemic circulation, sometimes at levels comparable to intravenous injection.

A distinctive advantage of sublingual medication administration is that it bypasses the liver and thus avoids hepatic first pass metabolism.15 Some medications are extremely sensitive to this first pass metabolism; for example, a healthy liver inactivates approximately 90% of oral nitroglycerine.16 Furthermore, variations in blood flow, including hypotension-induced shock-liver, as well as variations in hepatic enzyme activity, secondary to competition, make the drug’s metabolism in the liver unpredictable.

Sublingual medication can be given as either a liquid or a solid (pill). The Paramedic starts by lifting the tongue (assistance with a tongue blade is helpful) and depositing the medicine into the sublingual space. If the medication is a tablet or pill, it must dissolve to be effective. If the patient lacks saliva, a squirt from a pearl of sterile water can provide the needed solvent to accomplish liquefaction of the medication.

Patients who have received sublingual medication should be discouraged from smoking immediately afterward. Nicotine present in the smoke will produce vasoconstriction, hindering the absorption of the medication.

Buccal Route

Administering medications using the buccal route is similar to administering medications sublingually. In cases in which the patient has difficulty with lifting the tongue to the roof of the mouth (e.g., following a stroke), then the medication can be placed in the buccal pocket created by the cheek. Placing drugs in the buccal pocket has been a common practice since antiquity. Peruvian Indians used to stuff chewed coca leaves into their buccal pockets, thus absorbing the stimulant directly into the bloodstream. Tobacco has also been placed in the buccal pocket, as tobacco chew, and the nicotine absorbed into the central circulation.

Oral Route

Clearly, the vast majority of medications that are self-administered are swallowed. The medication—solid pill, capsule, or liquid—is then absorbed into the gastrointestinal tract where it is passed, via the portal circulation, through the liver and on into the central circulation. The image of a nurse passing pills in a paper medicine cup, also called a souffle cup, leaps to mind when one thinks of hospital care. However, Paramedics seldom use this route to administer medicine.

First, the absorption of medications via the gastrointestinal route can be protracted and erratic. Local conditions such as the presence or absence of food, stomach acidity, gastric motility, and mesenteric blood flow all influence drug absorption. Perhaps more importantly from an EMS perspective, the patient must be able to maintain the airway independently and swallow the medication. Paramedics are often called to the scene of a patient who is semiconscious, making this route impractical.

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