Technology and Clinical Applications Flashcards
Describe the composition and basic action of the heart.
The heart is basically a muscle, which means it expends energy by contraction. It is a hollow organ consisting of 4 compartments, with two different 2-sided pumps. The heart chamber called the right atrium passively receives deoxygenated blood from the body, either via the superior or inferior vena cava. After brief storage, the blood passes through the tricuspid valve, into the right ventricle, and then is ejected with positive pressure through the pulmonary valve. It then travels to the lungs by the pulmonary arteries where it becomes oxygen-rich. This oxygenated blood returns passively to the left atrium chamber of the heart via the pulmonary veins, passes through the mitral valve into the left ventricle, and is then pumped again through the aortic valve at higher pressure to other systems in the body.
Explain where and how the heartbeat is generated.
The heartbeat is an electrical response produced in the sinoatrial (SA) or sinus node. The sinus node is the part of the heart located at the junction between the superior vena cava (SVC), the vein that draws venous blood from the upper part of the body, and the right atrium chamber of the heart. Beats are usually generated at a rate of 60 to 100 beats a minute (bpm). The sinoatrial node is therefore the main pacemaker for the heart. Sympathetic and parasympathetic nerve fibers transmit electrical impulses to the SA.
Give a brief description of the parts of the systemic circulation.
Upon leaving the left ventricle of the heart, blood flows through the main artery of the body, the aorta. An artery is a vessel carrying blood from the heart under pressure. From the aorta, blood is carried into smaller arteries. Here the blood is bright red since it is oxygenated and it is pulsating. Arteries do not contain valves and most are located deep within tissue that is covered by muscle. Eventually these arteries terminate in smaller arterioles that form even thinner arterial capillaries. The arterial capillaries connect to venous capillaries to small veins, or venules. By this time the blood is dark because in the capillaries, an exchange of nutrients and oxygen has occurred between the blood and tissues and waste and carbon dioxide has been picked up. The venules unite to form larger veins, which eventually feed back to the heart by the superior or inferior vena cavas.
Explain the role of nerve conduction in the circulatory system.
Nerve conduction is a vital component in the operation of the circulatory system. In the heart itself, there is a system of atypical muscle fibers that transmit and synchronize the electrical impulses in the heart. This is why the right and left atria contract at the same time and later both ventricles do the same. The arteries are directly stimulated through sympathetic innervation controlling the contraction and relaxation of the vessels as well as indirectly by parasympathetic innervation. These signals are transmitted by release of the hormone norepinephrine and the compound acetylcholine respectively. Veins are controlled in a similar manner.
List the four anatomical parts of the brain and explain their primary functions.
The brain is basically a large mass of nervous tissue that occupies the cranium or skull. It is divided into four parts, the cerebrum, cerebellum, brain stem and ventricles. The cerebrum is by far the largest part of the brain. It is divided into four lobes or hemispheres named for their adjacent bones. These lobes are the frontal lobe, which controls higher intellectual and autonomic functions; the parietal lobe, affecting position, sense, touch and motor function; the occipital lobe, or vision center; and the temporal lobe, controlling most memory and perception of sounds. The cerebellum controls movement, equilibrium, muscle tonicity, and spatial relationships. The brain stem consists of three parts, the midbrain, the pons, and the medulla oblongata; their respective functions are to transmit stimuli from the spinal cord, to relay impulses to brain centers and lower spinal centers, and to control involuntary functions. The ventricles are spaces located deep within the brain that contain cerebrospinal fluid and connect with the fluid spaces in the spinal cord.
Briefly explain the structure and function of the spinal cord.
The spinal cord is a pathway to conduct impulses to and from the brain as well as a point of origin for spinal reflexes. The spinal cord consists of what is termed gray or unmyelinated matter and white or myelinated matter. The gray matter consolidates the cord’s reflexes, while the white matter that surrounds it is the impulse pathway linking the spinal cord and the brain. There are separate fiber tracts that either bring these impulses to the central nervous system (ascending) or carry sensory information from the brain to the spinal cord and other neurons (descending). There are also structures that protect the spinal cord such as the vertebral column and spinous processes. Spinal ligaments help hold the spinal vertebrae together. There are also three meninges or protective membranes covering the brain and spinal cord, the pia mater, the arachnoid mater and the dura mater.
Name some components of the peripheral nervous system.
Cranial and spinal nerves form the peripheral nervous system. In the brain area, there are 12 cranial nerves, which have either motor fibers, sensory fibers, or both. These nerves control voluntary muscular functions and the autonomic sensory abilities to see, hear, smell and taste. There are 31 different pairs of spinal nerves originating from different segments of the spinal cord. The cervical plexus and brachial plexus are complexes of nerve fibers supplying sensory and motor responses to the head and neck area and upper extremities respectively. Other spinal nerves include the thoracic, lumbar, sacral and cockerel nerves.
Briefly explain what the autonomic nervous system is and how it works.
The autonomic nervous system is the part of the peripheral nervous system that controls the involuntary internal functions in the body. These functions include the operation of internal organs, involuntary fibers, and glands. Portions of the hypothalamus, the brain stem and the spinal cord activate the autonomic nervous system. There are two types of nerves comprising the autonomic nervous system, sympathetic and parasympathetic. Sympathetic nerves respond to external stressors by releasing norepinephrine and transmitting impulses that increase blood pressure and heart rate and vasoconstrict peripheral blood vessels. Parasympathetic nerves operate when an individual is at rest or relaxed to maintain normal bodily functions.
List the arteries that can be used for vascular access.
A few arteries are sometimes appropriate for vascular access. The radial artery, which is a continuation of the brachial artery below the bend of the forearm extending to the wrist, is a site of choice. It is relatively close to the skin and if it is utilized at the wrist, it can be stabilized. The ulnar artery is larger but less superficial than the radial artery and is thus more difficult to stabilize. It is actually the terminus of the brachial artery and it extends below the elbow on the medial side of the forearm. The largest accessible artery is the femoral artery, but care must be taken to maintain dry dressings, apply digital pressure, and observe for thrombosis. The femoral artery is located halfway between the anterior superior spine of the ilium and the symphysis pubis. Sometimes the pulmonary arteries are used for vascular access. Blood can be drawn at the same time for arterial blood gases if arteries are accessed but the threat of circulatory problems or infections limit their use.
List the veins that can be used for peripheral infusion therapy.
A number of veins in the hand and forearm can be utilized for infusion therapy. The digital veins, which are those along the sides of the fingers and not that widely used, combine to form three metacarpal veins in the hand that are often used initially. This is because for later infusions, less distal sites can be accessed without pain or inflammation. These metacarpal veins form a large vein called the cephalic vein, which begins in the hand and flows higher along the radial border of the forearm. The cephalic vein is an excellent choice for infusion therapy. Another choice is the basilic vein, which runs along the ulnar or inner side of the forearm; this is the vein that becomes prominent when the arm is flexed and bent at the elbow. Other possible choices include the median antebrachial vein, the median cephalic vein, or the median basilic vein. The cephalic and basilic veins extend up the arm and can sometimes be used for central intravenous therapy.
List the central veins that are appropriate for central infusion therapy.
There are two different jugular or neck veins that are utilized for central infusion therapy, the internal jugular vein and the external jugular vein. The external jugular vein is the one easily observed on the side of the neck, and it is usually the vein of choice because of its easy access. When either jugular vein is accessed, there is a threat of air being pulled into the vascular system if the administration set becomes accidentally disconnected. The vein of choice for central vascular access devices is the subclavian vein, which is located under the collarbone. As a last resort, the health care provider could use the femoral vein.
Give examples of scalp veins that are used for infusion therapy.
The scalp vein that is most frequently utilized for infusion therapy is the frontal, or supraochlear, vein. This vein is on the forehead and the section running down the middle of the forehead is also called the metopic vein. In the pediatric patient, the superficial temporal vein is often used because it is easily visualized; this vein is on the side of the head and originates from a large network of veins on the scalp. Less frequently used scalp veins include the parietal vein and the occipital vein, which are found in front of and behind the ear respectively.
Give examples of some veins that are used in unique circumstances for infusion therapy.
The umbilical vein, which is actually located inside the umbilical cord traveling through the navel to the liver and ductus venous, is often utilized to administer infusions to newborns. There is, however, a high risk of septicemia using this route. In infants and children, a vein called the great saphenous vein is sometimes used for infusion. This vein runs along the medial portion of the leg originating at the ankle, and typically the lower portion above the ankle is used. The threat of thrombosis resulting in possible pulmonary emboli that can occur when using veins in the upper extremities is diminished.
List reasons to initiate infusion therapy.
Infusion is usually initiated for therapeutic reasons but sometimes it is done for diagnostic purposes. When a patient cannot sustain adequate uptake independently, therapeutic infusion is started to maintain levels of water, electrolytes, nutrients or nitrogen or to reequilibrate the acid-base balance. Medications, whole blood or its components, anesthetics, or pain relievers, if needed, constitute the main reasons to begin infusions. Infusion may also be started in order to administer some type of diagnostic reagent or to monitor hemodynamic function. In emergency situations, infusion is sometimes begun just to maintain unblocked vascular access.
Describe the components of patient assessment necessary before initiating infusion therapy.
Prior to administering infusion therapy, the health care professional must be armed with a variety of information. Some of this information is knowledge of the patient’s history, including primary and secondary diagnoses, conditions responsive to the therapy, possible side effects or allergies, and prior history of respiratory or coagulation issues, previous transfusions or fluid/ electrolyte imbalances. A variety of laboratory data should be obtained prior to therapy. In particular, evaluations of renal function such as blood urine nitrogen (BUN); electrolyte levels; complete blood count (CBC) and percentages of its components; coagulation issues such as platelet levels and prothrombin time; and respiratory state if needed determined by drawing arterial blood gases. Physical assessment of the patient should be done including vital signs, fluid taken in and excreted, skin and tongue turgor, observations of fluid volume deficit, presence of swelling, and changes in body weight.
Describe how dressings are used in infusion therapy.
Dressings are of two types, either sterile gauze or transparent semipermeable membrane (TSM) dressings. These dressings are aseptically applied after site insertion over the site and replaced whenever they appear damp, loose, or visibly soiled. The edges of gauze dressing should always be taped, but tape may compromise the properties of TSM dressings and interfere with the ability to see the site. When used together, the gauze dressing is usually covered with a TSM dressing. When changing dressings applied to central vascular sites, sterile gloves and a mask should be worn.
Name areas of the body that should be avoided when selecting infusion sites.
In general in adults, veins in the lower extremities should be avoided as infusion sites. This is because these veins have numerous interconnecting networks and also because they are distally located relative to the heart which makes them more susceptible to becoming inflamed, forming blood clots, or developing thrombophlebitis. Therefore, distal areas of the upper extremities are preferred. Arteries normally should only be tapped for to follow hemodynamics or to draw samples such as arterial blood gases, and not to administer medication because arterial spasm can occur which cuts off the blood supply to that area. Elderly patients often have areas of very thin skin that will not support a catheter. Areas with lesions, cellulitis, or weeping tissues should be avoided as well as injured veins. In patients who have had a mastectomy or axillary dissection, veins in those areas are generally avoided.
Describe how and why a catheter might be inserted into the ventricular reservoir.
Sometimes a receptacle attached to a catheter is surgically inserted into the lateral ventricle of the brain and then connected to the spinal space. By inserting a 25-gauge or smaller needle into this reservoir, two-way access to the brain or cerebrospinal fluid (CSF) is provided. Fluid can be injected or removed and medication can be delivered into the CSF. The need for repeated lumbar punctures is obviated with this technique. The drawbacks to this application are that infection or clogging can occur and strict sterile technique must be employed.
Explain what intraosseous administration is and why it might be performed.
Intraosseous administration is the process of infusing right into the bone marrow. It is usually done for short periods during emergencies when an intravenous insertion proves difficult. Since the internal marrow of the bones manufactures the red blood cells, this procedure provides an indirect route. Longer bones such as the distal tibia, proximal tibia, distal femur or iliac crest are typically used. 16 to 18 gauge needles are employed, strict sterile procedures followed, and the infusion should be removed within 24 hours. Since the bones used are all in the leg or ankle, conditions such as fractured or traumatized legs, osteoporosis, or burns or cellulitis in the area contraindicate use of intraosseous administration.
Describe the procedures involved in the removal of a catheter.
A physician’s order is needed to discontinue infusion therapy and can depend on a number of factors. The general guidelines are outlined in the Infusion Nursing Standards of Practice. For a short peripheral catheter, the health care provider should use good aseptic technique and apply pressure and a dry sterile bandage. Midline peripheral catheters may have had a dwell time as long as 4 weeks, so additional precautions are necessary including immediate removal if contamination or complications are suspected and applying antiseptic ointments. For arterial sites, pressure with the fingers needs to be applied upon removal until hemostasis occurs before applying dressings. When removing peripherally inserted central catheters, it is important to take precautions against development of air embolism. This is also true for central devices that were neither tunneled nor implanted. On the other hand, both tunneled central vascular access devices and implanted central vascular access ports should be removed by a physician, not the nurse.
List the basic types of solution containers and administration sets and their interrelationship.
Solution containers are of two types:
· The first type, glass bottles, depends on air for flow and thus creates open systems. Because the glass bottle does not collapse as solution flows, venting is required. This necessitates the type of administration kit that allows air to enter or in some cases a vented spike adaptor is used.
· Plastic bags provide another type of container, which is a closed system. The plastic bag collapses during solution flow preventing exposure to the air and the possibility of air emboli. Nonvented administration sets are used with plastic bags. There are also administration sets that have dual vented/ nonvented applications as the cap can be opened or kept closed.
Discuss the following vein location devices for infusion therapy, including indications for use: Transillumination and ultrasound.
Finding veins to access can be difficult for patients with small or very fragile veins (such as children and older adults). Vessels should be 2 to 3 times the diameter of a catheter, so transillumination devices help to locate appropriate sites for placement. Two different types of devices help to identify the position and size of veins: ·
Transillumination: These devices, such as the Venoscope ® and Transillumination Vein Locator ®, utilize high intensity LED lights in a handheld device. The lights illuminate and shine through the subcutaneous tissue, allowing visualization of the veins. While still illuminated, the vein can be anchored by the nurse to prevent rolling before needle insertion. · Ultrasound: Ultrasound-guided peripheral IV (USGPIV) placement is utilized for difficult to access veins, such as in patients with hypovolemia, severe edema, obesity, or scarred vessels. The probe should be covered with a sterile transparent dressing before applying sterile gel. The vein may be located with or without a tourniquet in place. The vein and the needle are tracked on a monitor, which can guide insertion into the vein.
List the different ways administration sets are constructed and their uses.
Some administration sets are designed just to deliver a single primary solution or medication.
· Straight sets, which may not have an injection port, are used for this purpose.
· Other types of sets permit administration of secondary medications or solutions, commonly referred to as “piggyback solutions”. There are a number of these types of sets, including the check-valve set, the secondary set, or a Y-type set. The check valve set has an integrated valve that allows a secondary solution to be injected through it and administered without cross-mixing when the height of the primary solution is lowered. The secondary set is a very short set that is attached above the check valve through a Y-configured port. The Y-type set is used with a filter or integrated hand pump.
· Other variations include a controlled-volume set, which contains a vented calibrated chamber, a retrograde set primarily used for children and neonates, and a dedicated set, which is always used with a specific device.
List some special considerations to observe when using administration sets.
Special considerations when selecting and utilizing an administration set include:
· Some administration sets contain latex parts and should not be used for patients with latex sensitivity.
· Sets made of polyvinyl chloride cannot be used with certain medications, notably Taxol.
· The set diameter and consequent drip rate must be taken into consideration.
· The injection and access ports should be needleless and should be located beyond the drip chamber close to distal end of the set.
· Sets should be changed if contamination occurs or if any changes in the product are suspected.
· When lipid emulsions or blood products are being administered, the sets should be changed every 24 or 4 hours respectively.
· The solution should be changed as well when symptoms in the patient suggesting infection or cardiac response are observed.
Describe the preferred type of connectors for administration sets and catheters. List other types of add-on or junction securement devices.
The preferred type of connecter in infusion is the Luer-Lok. It allows an administration kit to be connected to an additional device or catheter with minimal possibility of accidental disconnections that might put the patient at risk. This is accomplished by inserting the male Luer of the administration kit into the female Luer of the other device with a locking clasp. A similar Luer slip without the locking device is not as good because it can pull apart. Add-on devices can include extension sets, stopcocks, injection or access ports for administration of intermittent or short-term therapy, devices that keep catheters in place, vented spike adaptors, caps, and other devices.
List the three types of filters often used in conjunction with infusions and give their advantages and disadvantages.
Three types of filters often utilized in infusion therapy include the following:
Some administration sets have filters directly uncorroborated into the design, known as “in-line.” In this case, there is very little risk of contamination because the filter cannot separate from the set. On the other hand, these are usually located in the upper part of the set and do not filter lower add-ons and if they clog the whole set must be changed.
· An add-on filter can be placed anywhere, particularly at the distal end of the set, which is preferable, and it can be easily changed if clogged or defective. However, it can become separated from the administration set.
· Sometimes, if a medication is to be given as a large single dose, a filter needle that may retain particles from 1 to 5 microns in size may be utilized.
Describe the structural and retentive properties of different types of filters.
Membrane filters are screen-type filters possessing uniformly sized pores or holes. They keep any particle larger than the pore size on the membrane, and thus they are usually the type of filter used to retain and filter out bacteria, fungi, or unique contaminants. The 0.2-micron pore size is routinely used to filter bacteria out of intravenous solutions. It should not be utilized for blood products, lipids, intravenous push, or with some medications. Larger filters with pore sizes of 1 or 5 microns filter out particulate matter. A special size of 1.2 microns is generally used to administer total nutrition admixtures. Other types of filters are called depth filters, consisting of irregularly sized fibers and used to filter particulates only, and hollow fiber filters, which are made of fibers that withstand high pressure.
Describe the filters used for administration of blood products.
Blood filters are integrated right into some administration sets and are designed to remove either particulate matter or specific blood components from the blood or its components. Standard blood filters have a much bigger pore size than those used for intravenous solutions, ranging from 170 to 260 microns. Microaggregate blood filters have a smaller pore size of only 20 to 40 microns and are really only used during heart bypass surgery or for repeated transfusions because their small pore size slows the flow rate. There are also two types of leukocyte-reduction filters available, one that removes leukocytes from red blood cells and another that removes leukocytes from platelets.
Describe how the two different classes of electronic infusion devices work.
Electronic infusion devices are either controllers or positive-pressure infusion pumps. ·
A controller is an electronically controlled device that dispenses fluids merely by the aid of gravity. A desired flow rate is set on the device and the tubing pressure is regulated by counting the drops. In this case, the solution must be placed about 3 feet above the catheter insertion site to aid gravity.
Another type of device, the positive-pressure infusion pump actually exerts pressure to circumvent resistance. It is used to administer medications especially complex therapies, when large volumes are given, or when great attention is necessary since these pumps should be more accurate. The average pressure delivered is about 5 to 10 pounds per square inch (psi).
