Ultrasound Use in Cardiothoracic Surgery

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Home Study Program ULTRASOUND USE IN CARDIOTHORACIC SURGERY

he article “Ultrasound use in cardiothoracic surgery” is the basis for this AORN Journal independent study. The behavioral objectives and examination for this program were prepared by Helen Starbuck Pashley, RN, MA, CNOR, contributing editor, with consultation from Eileen J. Ullmann, RN,MHS, CNOR, professional education specialist, Center for Perioperative Education. A minimum score of 70% on the multiple-choice examination is necessary to earn 3.5 contact hours for this independent study. Participants receive feedback on incorrect answers. Each applicant who successfully completes this study will receive a certificate of completion. The deadline for submitting this study is Jan 30, 2004. Send the completed application form, multiple-choice examination, learner evaluation, and appropriate fee to AORN Customer Service c/o Home Study Program 2170 S Parker Rd, Suite 300 Denver, CO 8023 1-5711 Or fax the information with a credit card number to (303) 750-3212

BRHAWORAL OBJECTIVES

After reading and studying the article on ultrasound use in cardiothoracic surgery, the nurse will be able to ( 1 ) discuss cardiovascular disease, (2) describe the anatomy and physiology of the vascular system, (3) discuss the use of ultrasound in coronary artery bypass (CABG) procedures, and (4) describe the care of the patient undergoing a CABG procedure.

This program meets criteria for CNOR and CRNFA recertification, as well as other continuing education requirements.

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Ultrasound Use in Cardiothoracic Surgery ardiovascular disease is the leading cause of death in the United States and has been every year since 1900, with the exception of 1918. According to the American Heart Association, in 1997, 953,110 deaths in the United States were the result of cardiovascular disease. This represents 41.2% of all deaths in 1997. Of these, 49% were attributable to coronary artery disease.' In a patient with cardiovascular disease, the coronary arteries supplying the heart with blood become narrowed by fatty deposits or plaques and cause decreased blood flow, oxygen deprivation, and ultimately, cardiac tissue damage. If a coronary artery becomes so clogged that part of the heart muscle dies, the patient suffers myocardial infarction. The plaques that form in the coronary arteries are composed primarily of cholesterol, lipids, and cellular debris. The development of arterial plaque is known as atherosclerosis. Fatty deposits build up in the lining of the arteries.

The risk of developing coronary artery disease is increased if the patient smokes, has a history of hypertension, has developed high blood cholesterol, is obese, has a family history of coronary artery disease, or has diabetes. Treatment of coronary artery disease includes lifestyle adjustments, medication, or invasive procedures (eg, cardiac catheterization with balloon angioplasty, coronary artery bypass surgery). Cardiothoracic surgery requires multiple levels of vessel identification and location. During a coronary artery bypass grafting (CABG) procedure, it becomes necessary to locate and identify the saphenous vein for harvest; the radial artery for invasive blood pressure monitoring or harvesting; and the internal jugular for central line access, pulmonary artery catheter monitoring line access, and epiaortic (ie, outer layer or outside the aorta) ultrasound for plaque before cross clamp placement. When using traditional methods for identifying and locating these vessels, the RN fiist assistant (RNFA) has relied on knowledge of anatomy and physiology, plus experience. A common way of A B S T R A C T With the advent of minimally invasive surgical techniques, finding the proximal end of the patients in the United States currently are undergoing safer, more saphenous vein has been to meascomfortable surgical procedures than in the past. Traditionally, ure two finger widths medial of the saphenous vein harvesting techniques involved open surgical tech- iliac crest and two finger widths niques that could become sources of postoperative complications, inferior. To find the saphenous including pain, poor wound healing, increased length of hospital stay, vein at the distal end, the RNFA and higher costs for the patient and hospital. These complications applies pressure to the saphenous were the impetus for developing minimally invasive techniques for vein just above the medial malleovein harvesting. Minimally invasive saphenous vein harvesting is per- lus and gently strokes the leg formed through small incisions and subcutaneous tunnels. The pro- downward or distally along the cedure offers an atraurnatic conduit for the coronary artery bypass posterior tibia with one finger. procedure and decreases the number of leg wound complications. This allows the RNFA to note the Ultrasound devices currently offer a quick, accurate method for locat- vein filling, and direction, as well ing veins before harvest, thereby avoiding wound complications and as to obtain a size estimate. The use of newer technology injuries. AORN J 73 (Jan 2001) 144-165. ROD HECKMAN, H N 144 AORN JOURNAL

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involving ultrasound provides a safer surgical experience for patients undergoing a cardiovascular procedure. Ultrasound offers a safe, noninvasive method of identifying multiple arteries and veins before beginning invasive surgical procedures, thereby saving the patient additional discomfort, time, and increased supply and instrument expenses. ANATOWAND PHySlOuHiY

Human understanding of the venous system has developed slowly. Early attempts to describe the vascular system began with Galen in the second century, were advanced by Leonard0 da Vinci during the Renaissance, and were advanced further by William Harvey in the 1600s. Human understanding has grown enormously and has allowed medical science pioneers (eg, DeBakey, Bamaard) not only to document what happens in the vascular system, but to surgically alter it when necessary. When compared to the structure of arteries, veins appear to be thin-walled and weak. Under normal conditions, however, they are quite strong and durable. Veins, like arteries, comprise three tissue layers (ie, tunica intima, tunica media, tunica adventitia). Veins contain smaller amounts of collagen, muscle, and elastic tissue than arteries. Endothelial cells comprise the intimal layer and are supported by a thin membrane and an elastic lamina. The endothelium of a vein may be no more than one cell thick. The intima appears to be a simple physical structure, but it is biologically active and mediates many blood clotting activities. Endothelial cells for example, produce fibrinolysis activators in larger quantities than arteries. Prostaglandins, especially prostacyclin, are secreted in all veins and have a distinct antiplateletaggregating property. These substances also are inhibitors of thromoxane, which is a platelet aggregator derived from the platelets themselves. Clotting factor VIII also is produced by the endothelium of veins. Muscle fibers arranged in various striae form the tunica media of veins, for example, in medium-sized vessels. The configuration depends on the size and function of the vein. Elastic fibers and connective tissue support and separate the layers, usually three in number. The muscular layers create vein contractility, which maintains venous tone. The outer layer of veins comprises the tunica adventitia. This layer primarily is supportive. It derives its strength from interwoven collagen whose fibers run in different directions. Prominent in larger veins, elastic tissue permits the distensibility

necessary to accommodate changes in venous volume without changing venous pressure. The adventitia is attached loosely to the surrounding tissues. Nourishment is provided to the vein wall by vasovasora, which enter through the adventitial layer. In the normal state, the thin-walled construction of veins permits compression in response to muscular contraction and distension to compensate for volume changes. The fragility and lack of surrounding tissue support, however, render veins vulnerable to increased blood volume and venous hypertension. Vessels used in cardiothoracic surgery. Veins taken from other sites in the patient’s body traditionally have been used to replace diseased or blocked vessels supplying blood to the heart. Greater saphenous vein. The greater saphenous vein takes its origin from the medial limb of the dorsal arch and runs from the foot to the groin on the inner surface of the leg (Figure 1). As the major superficial collecting and transport vein of the leg, it also is the longest vein in the body. Its accessibility and inherent strength make it a favorite choice for CABG and other vascular substitution procedures. From the ankle, the saphenous vein ascends the calf along the border of the gastrocnemius muscle. It is in

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Figure 1 The greater saphenous vein takes its origin from the medial limb of the dorsal arch and runs from the foot to the groin on the inner surface of the leg. (Illustration by Mark Katnik, Denver)

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its most superficial position as it passes over the medial condyles of the tibia and femur. It continues in front of the popliteal crease and, on an oblique path, directly up the thigh on the medial border of the sartorius muscle, where it measures 3 mm to 5 mm in diameter. As it ascends, it lies directly on the muscular fascia and beneath the superficial fascia. It joins the femoral vein approximately 2 cm to 3 cm lateral to and 2 cm to 3 cm inferior to the pubic tubercle. The saphenofemoral junction lies in the center of the femoral triangle, also known as Scarpa’s mangle. Lesser saphenous vein. Another leg vein used for CABG is the lesser saphenous vein. It originates as the lateral limb of the dorsal venous arch and receives blood from marginal veins in the sole in the foot. It also shares branching with the anterior arch vein, and it shares drainage with the great saphenous vein by way of large intersaphenous bridges located on the medial calf and smaller tributaries that cross the Achilles tendon. From the lateral foot, it runs beneath the lateral malleolus, ascends in the groove between the malleolus and Achilles tendon, and a few centimeters higher, turns to the center of the calf and runs

Figure 2 The radial artery lies on the lateral aspect of the forearm and runs from the proximal branching point off the brachial artery distally toward the lateral wrist and hand. (Illustfufion by Mufk Kufnik, Denveij

subcutaneously over the tendon. At midcalf, the lesser saphenous vein enters an intrafascial envelope between the bellies of the gastrocnemius muscles, penetrates the envelope in the upper-calf, and runs beneath the muscular fascia to enter the popliteal fossa. Its usual diameter is between 3 mm and 5 mm throughout its course. Radial artery. The radial artery lies on the lateral aspect of the forearm and runs from the proximal branching point off the brachial artery distally toward the lateral wrist and hand (Figure 2). A continuous palmar arch exists that connects the ulnar and radial arteries in the palm or anterior of the hand. An Allen’s test allows the RNFA to test for artery dominance by detecting the pulse of both radial and ulnar arteries, observing the patient’s capillary refill times, and occluding flow through the radial artery. Another test used to determine artery dominance is the pulse oximetry. Pulse oximetry allows identification of perfusion throughout the hand and fingers. If the patient is u l n a dominate, the ulnar artery will continue to provide tissue perfusion to the hand and fingers, and the radial artery can be harvested. If the patient is radial dominate, the RNFA notifies the surgeon that the radial is not a possible donor artery. A Doppler also can be used to provide the same information. After acquiring Doppler sounds at the palmar arch, the RNFA occludes the radial artery flow. If the sounds continue without lessened volume, changes, or loss of signal, the radial is a good donor artery. Arm veins. Arm veins are a good conduit, especially for patients who are having procedures redone and whose saphenous veins were used in previous CABG surgery. The lesser saphenous vein, arm veins, and radial artery grafts also are available for use.’ The intermediate or median antebrachial vein of the anterior forearm offers a conduit 2 mm to 4 mm in width and is long enough to graft most target coronary arteries (Figure 3). The median vein runs from the wrist just proximal to the palm and continues to the antecubital fossa. At this point, it branches into the cephalic vein on the lateral aspect of the biceps muscle and the basilic vein on the medial side of the muscle. Other vessels requiring access. Anesthesia care providers must identify and locate the internal jugular veins for pulmonary artery catheter line placement. The internal jugular veins are the principal vessels draining the venous sinuses. The right internal jugular is the vein of choice because it offers a direct route for line insertion through the right heart and placement into the pulmonary artery.

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The surgeon also has the opportunity to view the carotid arteries while performing an ultrasound examination of the neck. In older patients undergoing cardiovascular and vascular procedures, there is a risk of stroke due to unrecognized carotid d i ~ e a s e . ~ Performing a noninvasive ultrasound examination of the carotid arteries makes the surgeon and team members aware of potential problems and thereby reduces the risk of stroke for the patient. When the pericardium is opened and exposed, the aorta can be examined directly. Initial examination and digital inspection enables the surgeon to evaluate the aorta’s status, but further examination is needed to avoid the possibility of stroke. Approximately 10% to 20% of patients who suffer strokes after surgery are believed to have experienced an embolic stroke from the heart or ascending aorta: The branches of the aortic arch are unimpaired except for the coronary arteries and sinuses. When patients present with occlusive disease of the ascending aorta, it takes the form of atherosclerotic lesions with associated fronds (ie, light, floating, feathery) of tissue floating in the bloodstream. These fronds of athero- Figure 3 The intermediate (median) antebrachial sclerotic and thrombotic material, known as athero- vein runs from the wrist just proximal to the palm and ma, may embolize and cause strokes or distal continues to the antecubital fossa. At this point, it ischemic damage. When patients who suffer strokes branches into the cephalic vein on the lateral aspect of are screened by transesophageal echocardiography, the biceps muscle and the basilic vein on the medial atheroma are found in the ascending aorta and con- side of the muscle. (///ustrotionby Murk Kutnik, sidered the likely source for the stroke. The develop- Denver) ment of calcification often is preceded by a history of radiation or inflammatory disease (eg, rheumatoid arthritis, severe arthntis). If calcium is identified in percent of blockage will determine exactly which arteries require bypass grafts, the aorta, the surgeon can alter his or her approach to the number of vein or artery conduits needed, cannulation and proximal graft sites by cannulating in the configuration of those bypasses (ie, arterial or a noncalcified area, cannulating in the femoral vesvein conduits), and sels, or grafting to the left subclavian artery. T-grafts needed for artery-to-artery, vein-to-vein, or sequential grafting using the artery or vein for SYMPTOMS AND DIAGNOSTICTESTING more than one anastomosis site. The symptoms of coronary artery disease Sequential grafting is accomplished by using the include dyspnea, diaphoresis, weakness, anxiety, electrocardiogram (ECG) changes demonstrating same conduit for two or more target coronary arteries. depressed or elevated ST segments and elevated T- Additional preoperative examinations include a comwave changes, nausea, pallor, cardiac enzyme eleva- plete blood count (CBC), urinalysis, chemical analytion, and chest pain unrelieved by rest or medication. sis, protime (PT), partial thromboplastin time (PTT), Patients often complain of pain in the chest, jaw, platelet count, and pregnancy testing, if applicable. These laboratory tests give surgical team members a neck, one or both arms, and the back.> Diagnostic testing for coronary artery disease chance to detect potential bleeding and coagulation usually includes a baseline ECG, stress testing for problems, the presence of infection, or any electrolyte further cardiac function information, and cardiac imbalance. A posterior, anterior, and lateral chest xcatheterization to identify the blocked arteries. The ray; carotid Doppler studies; pulmonary function testlocations of the coronary lesions or blockages and the ing; and type and cross matching for two to four units 147 AORN JOURNAL

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saphenous veins by slightly turning the legs outward while elevating them. It also offers relief to the patient’s lower back during the extended period of PREOPERATIW PHASE Preoperatively, the patient is given instructions time spent on the OR bed. A presurgical check sheet has been developed at to shower using an antiseptic scrub preparation the night before and morning of surgery. He or she also is our facility that allows the surgeon or RNFA to desprescribed a sleeping medication. Patients undergo- ignate specific needs for the procedure. Position of ing elective CABG procedures arrive at the same day the patient, incision type and location, anesthesia surgery department the morning of the procedure, and type, perfusion needs, and equipment are listed as the surgeon obtains the consent. The anesthesia care options for each procedure. The choice of conduits provider starts an IV line of lactated Ringer’s solution also can be communicated to surgical staff members. and administers preoperative medications, including For the CABG procedure, the patient is placed in a an antibiotic. The nurse takes the patient’s height and supine position with a medium-sized, padded support weight, records them, and confirms that the patient under the shoulders to extend the chest forward. The incision is usually a sternotomy, and general anesthehas been NPO since midnight. The perioperative nurse pays special attention to sia is used. Radial arterial lines, a pulmonary artery the preoperative surgical patient due to the amount of catheter, and IV lines also are required. Perfusion anxiety present. Physiologic and psychologic factors options include routine setup, off-pump or standby, often affect the patient’s anxiety regarding surgery active venous drainage, and multiple choices of canand his or her perceived self-confidence about post- nulae. Conduits include the left or right internal operative recovery. The RNFA must help the patient mammary artery, a radial artery, saphenous vein, lessunderstand his or her disease process and the steps er saphenous vein, arm vein, or gaswoepiploic artery. Equipment varies according to each patient’s needed to continue medical and nursing treatment during the preoperative, intraoperative, and postoper- specific needs. Equipment can include thoracoscopes ative phases of the CABG procedure. Psychosocial for minimally invasive procedures, an ultrasonic assessment often reveals this anxiety and fear and scalpel for internal mammary harvesting, temperature behaviors correlating to the severity of the procedure. regulating blankets to be used under the patient or on The patient is informed of the risks involved in sur- nonsurgical areas of the body, camera equipment for recording the procedure, and special instrumentation gery, including a 2% to 5% possibility of stroke or death, (eg, retractors, longer instruments) for minimally a 2% to 5% risk of infection and wound healing invasive procedures. Nursing diagnoses. The risk for infection relatproblems, a 1 in 500,000 chance of contracting HIV, and ed to surgical intervention and invasive monitoring a 1 in 100,000 chance of contracting hepatitis lines exists with CABG procedures. Interventions that assess the patient’s risk for infection and preserve from blood transfusions.6 Operating room preparation. We use a custom- skin integrity are important. Strict aseptic technique, made cardiothoracicpack as well as extra supplies and proper skin preparation, and controlling the number instruments specific to the procedure. The circulating of personnel in the OR are essential. The patient is at nurse and scrub person have the supplies assembled risk for hypothermia related to exposure to the cold on a cardiac procedure cart. As the supplies are used OR environment and extensive skin exposure during for procedures, perioperative staff members will pick the CABG procedure. This risk is assessed by nursing another procedure cart and have it ready for any emer- staff members when planning for temperature regugencies or for the next day’s procedures. While the lating blankets during the procedure, warm blankets scrub person opens the pack and supplies, the circu- during induction and immediately postoperatively, lating nurse gathers patient comfort equipment and fluid-warming devices for use by the anesthesia care supplies (eg, padding for the arms, heels, and head). A provider, and a heater-cooler device for use by the roll is placed under the patient’s shoulders to elevate perfusionist. Fluid and electrolyte imbalances are a risk for and level his or her stemurn. Also required for cardiothoracic surgery is a padded bolster placed under the any patient during coronary bypass. In addition to the thighs to help secure the patient’s legs in a frog-leg patient’s preoperative status and the amount of time position. This bolster facilitates the harvesting of on the bypass pump, frequent blood testing to monitor of packed red blood cells also are performed.

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hemoglobin, hematocrit, and electrolytes during the postoperative stay, and manage costs are evident. procedure increase the risk of fluid and electrolyte Minimally invasive vein harvesting is less traumatic imbalance. The RNFA and surgical staff members to the extremities, yields fewer complications, and must pay close attention to the patient's response to improves patient satisfaction. pertinent questions about his or her medical history. Lower leg incisions frequently are a source of Surgical team members must assess the patient for inadequate healing and wound complications that any previous surgical procedures that might affect the lead to patient discomfort and dissatisfaction. Minor harvesting of conduits. In addition, team members wound complications include hematomas, ecchymomust assess the patient for use of cardiac, antiarrhyth- sis, erythema, and edema. Major complications mic, or anticoagulant medications; antiplatelet agents; include suppurative bacterial infection, cellulitis, and the presence of allergies, smoking, activity intoler- dehiscence. Leg infections are a known complication ance; and any concurrent medical problems. Any of of saphenous vein harvesting, occumng at a rate these can affect the course of surgery and may require between 1% and 24% and are associated with a change of planned interventions. increased morbidity and increased costs for the Nursing care plans often are developed from the patient." Despite an absence of demonstrable complipathophysiologic aspect of the patient's care. There is cations, patients frequently complain of postoperative a pronounced effect on the physical and emotional discomfort, pain, or dysesthesias, especially around integrity of the person with cardiovascular disease; the knee and ankle areas. Although saphenous vein therefore, many nursing diagnoses apply to the cardiac harvesting often is considered to be of secondary patient. Table 1 identifies nursing diagnoses, interven- importance, the patient often complains more about tions, and outcomes applicable to the care of patients leg wounds than chest wounds after a CABG. Also, undergoing cardiac procedures using ultrasound. cosmetic results of saphenous vein harvesting are variable, with poorer resuIts in obese and diabetic PROCEDURE patients." Vein harvesting is a complicated and intricate Hawesting the saphenous vein. Minimally part of the CABG procedure. It also is associated with invasive saphenous vein harvesting is performed its own set of complications and postoperative mor- through small incisions and subcutaneous tunnels. bidity.' The saphenous vein first was used for coro- Atraumatic harvest of the conduit is of maximum nary revascularization in 1962.8 In May 1967, sur- importance. Excessive traction is not necessary and, geons began using reversed saphenous vein bypass if applied, will disrupt the endothelial integrity of the grafting. Multiple successful bypasses were per- vein, possibly causing accelerated atherosclerosis of formed using multivessel revascularizationduring the the endothelium that is breached. next few years. The saphenous vein then was used for The surgeon can perform the dissection by a multiple sequential bypass in 1972.9The saphenous sweeping the areolar tissue away from the conduit. vein is easy to handle, in abundant supply, and He or she allows the vein to lay undisturbed until all demonstrates superior flow rates to those of the inter- other tissue has been dissected and uses Metzenbaum nal mammary artery. The removal or harvest of the scissors to push the areolar tissue sideways until a saphenous vein is relatively easy compared to the branch is identified. It is imperative that each side internal mammary artery. In emergency situations branch of the saphenous vein be identified and bleed(eg, procedures involving patients with poor ventric- ing be controlled before division. Even small branchular function, older adult patients), the saphenous es that are torn or cut will quickly retract into the arevein is preferred. The saphenous vein remains a good olar fat causing hematomas and ecchymosis during choice of conduit for CABG. heparinization. After division of the branch, the surTraditional saphenous vein harvesting tech- geon moves the conduit in a lateral sweeping maneuniques create incisions that are common sources of ver forward until the conduit is freed. He or she lifts postoperative complications. Many attempts have the vein gently and sharply divides any remaining been made to reduce this morbidity. Several specialty adhesions. The success of minimally invasive vein companies either have or are developing products to harvesting relies on control of the bleeding, as well as aid in performing vein harvesting via minimally inva- atraumatic harvesting. Any bleeding into the tunnel sive techniques. The need to reduce pain, decrease spreads through the entire wound. Accumulation of a wound healing complications, decrease the length of hematoma causes not only pain but also extremity 149 AORN JOURNAL

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Table 1 m n m CARE PLAN Intervention Implements aseptic technique.

CARDI~~ORACIC UURASOUND

Nursing diagnosis Risk for infection related to surgical intervention and invasive monitoring.

Assesses susceptibility for infection; classifies surgical wound (eg, class I).

Outcome The patient is free from signs and symptoms of infection.

Performs skin preparations Minimizes length of invasive procedure by planning care and obtaining necessary equipment. Initiates traffic control. Surveillance Administers prescribed prophylactic treatments; administers prescribed antibiotic therapy as appropriate. Administers care to invasive device sites Dresses wound at completion of procedure. Risk for perioperative positioning injury related to need for surgical site exDosure.

Identifies physical alterations that may affect procedure-specific positioning. Positions the patient (eg, roll beneath

The patient is free from signs and symptoms of injury related to positioning,

shoulders, frog-leg, elevate hip). Evaluates for signs and symptoms of injury as a result of positioning.

Risk for injury related to extraneous objects and use of electrical, chemiGal, mechanical, or thermal sources.

Confirms patienrs identity before procedure; verifies allergies, NPO status, consent signed for planned procedure. Implements protective measures to prevent skin and tissue injury due to thermal, electrical, mechanical, or chemical sources; demonstrates knowledge of correct line placement; The RN first assistant (RNFA) performs meticulous, gentle dissection; avoids mechanical trauma during vein harvest; avoids hypothermic exposure of the vein. Performs required counts Uses supplies and equipment within safe parameters. Records devices implanted during operative or invasive procedure (eg, pacemaker, IV lines, chest tubes). Evaluates for signs and symptoms of injury to skin and tissue.

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The patient is free from signs and symptoms of injury related to physical injury or injury from extraneous objects or electrical, chemical, mechanical, Or thermal sources.

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Table 1 CARDIOTHORACK ULTRASOUNDpAnw CARE PLAN (CONTINUED)

Nursing diagnosis Risk for impaired skin or tissue integrity related to surgical intervention, medical condition, patient behaviors (eg, smoking)

Intervention Identifies baseline tissue perfusion; inspects skin and identifies alterations before surgery. Assesses for preexisting conditions that predispose patient to inadequate tissue perfusion.

outcome The patient has wound and tissue perfusion consistent with or improved from baseline levels established preoperatively.

Collaborates in fluid management. Administers blood product therapy as prescribed. Evaluates postoperative tissue perfusion.

Risk far fluid volume deficit related to loss of fluids.

Recognizes and reports deviation in diagnostic study results; performs frequent blood testing. Collaborates in maintenance and corrective therapy; monitors heparin and protamine dosage.

The patient's fluid, electrolyte, and acid-base balance is consistent with or improved from baseline levels established preoperatively.

Monitors physiologic parameters (eg, "on pump" time, frequent blood testing; assesses laboratory values), Performs venipuncture; establishes IV occess; administers IV fluid therapy. Decreased cardiac out. put related to physical health status.

Identifies baseline cardiac function. Identifies and reports presence of implantable cardiac devices (eg, pacemaker).

The patient's cardiac function is consistent with or improved from baseline levels established preoperatively.

Evaluates postoperative cardiac function Fear related to physiologic and psychologic factors associated with cardiac disease, surgical procedure, and unfamiliarity with information resources.

Identifies physiologic and psychologic barriers to communication Determines knowledge level based on physiologic and psychologic status

The patient demonstrates knowledge of the physiologic and psychologic responses to the operative or other invasive procedure.

Assesses readiness to learn based on physiologic and psychologic status Assesses coping mechanisms based on physiologic and psychologic status Evaluates responses to instruction, elicits perceptions of surgery

Risk for hypothermia related to exposure to cold environment and extensive skin exposure.

Implements thermoregulation measures (eg, warm blankets, thermoregulating devices for patient, anesthesia care providers, and perfusionists) Monitors body temperature Evaluates response to thermoregulation measures 151 AOKN JOURNAI.

The patient is at or returning to normothermia at the conclusion of the immediate postoperative period.

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edema and drainage. All of the advantages of minimally invasive saphenous vein harvesting are lost if bleeding occurs. If all side branches are controlled, these wounds are so innocuous that the patient often is unaware of their presence. Traditionally, the saphenous vein has been harvested through a long continuous incision, a technique that preserves the vein from intimal disruption and prevents early or late closure, which is important. Major complications of the large wound, such as skin loss or purulent infections, result in a significant morbidity for an estimated 1% to 5% of patients. These require prolonged hospitalization. Minor complications (eg, saphenous nerve damage, hematomas, prolonged lymphatic drainage, fat necrosis with cellulitis, chronic edema) can occur at a much higher rateas much as 20%.**Research has shown that leg infections are a complication of saphenous vein harvesting that “occur at a rate between 1% and 24% and are associated with extra morbidity and increased costs for patients.”” Some basic guidelines are required to reduce vein harvesting complications regardless of how vein harvesting is performed. The following must be considered to reduce complications. Preoperativeplanning must allow for patients with obesity, diabetes mellitus, severe peripheral artery disease, and preexisting venous stasis changes. Techniques that prevent the development of large skin flaps must be used (eg, tracking the direction of the vein using scissors to tunnel on top of the vein before a large incision is made may prevent the development of large skin flaps that could then lose their blood supply and cause a tissue slough). The leg wound must be closed after the heparin has been reversed. The incision must be made over the vein with a knife and continued with scissors. Electrosurgery must be used for hemostasis and not cutting tissue, which prevents vein damage due to electrosurgical heat exposure. Lower extremity wounds in patients who are obese must be closed with interrupted absorbable sutures, and loose tissue must be debrided to reduce the cellulitis produced by fat necrosis. The saphenous nerve and its branches below the knee must be avoided with meticulous dissection and careful closure techniques that avoid pulling nerve tissue into the closure. Elastic wraps should be avoided after the first

24 hours due to constriction, which further causes swelling. Waiting to close leg incisions until the heparin has been reversed is particularly important for the thigh incision and will assist in reducing hematoma formation. The systemic dose of heparin, which is in the range of 20,000 to 35,000 units, will cause bleeding at the arteriole end points seen in the leg incision. Heparin inhibits normal coagulation factors and prevents clot formation. If the incision is closed and generalized bleeding or oozing occurs, a hematoma can form causing tissue damage and leaving open or dead spaces that can be a source of infection or complication. When protamine sulphate has been infused at a therapeutic level (ie, 1 mg per 1,000 units of heparin), it acts as an antagonist toward the heparin and causes a reversal of the anticoagulant activity of heparin; thus the leg wound will have less arteriole bleeding and hematoma formation. One of the advantages of minimally invasive vein harvesting is the absence of deep lateral flaps in the leg. Flaps occur when a large incision is made only to discover the vein is quite a distance away. Large subcutaneous flaps, the result of extensive dissection of the vein far from the initial skin incision, are notorious for poor healing, infection, and dermatolysis. When minimally invasive techniques are used, these flaps do not occur. The surgeon tracks the vein visually allowing the RNFA to remain directly on top of the conduit at all times. This reduces flaps and subcutaneous tissue division, decreases blood loss, and maintains higher postoperative hematocrit levels. Graft injury to any conduit used for revascularization of the coronary arteries is of special concern. Anticoagulation, procoagulation, immune function, vasorelation, and vasoconstriction are necessary if the vein is to function properly. These functions, when preserved and in balance, not only may prevent early thrombosis but also could inhibit the later development of fibrointimal hyperplasia and atherosclerosis. To minimize injury and assure graft resistance to acute thrombosis as much as possible in the early postoperative period, proper graft preparation is invaluable and should include principles, such as meticulous dissection to avoid crushing or stretching the graft; gentle distention using 1,000 units heparin to 100 mL saline solution, Hank’s solution (ie, cell culture with phenol red and without calcium or magnesium), or papaverine HCL solution 90 mg

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per 90 mL of normal saline to prevent endothelial cell rupture; avoiding mechanical trauma during harvest; avoiding disruption of versa vastum; use of blood rather than crystalloid solutions of low oncotic pressure to maintain the viability of endothelial cells; avoiding prolonged hypothermic exposure of the vein, which may cause endothelial cell detachment; and use of antiplatelet medications to improve shortand long-term patency. TECHNOLOGY DESCRIPTION AND DESIGN

The saphenous vein easily can be mapped using an ultrasound device (Figure 4), and the RNFA can mark the vein on the skin surface with an indelible, waterproof marker as he or she follows the vein the length of the leg. After the vein is identified, the RNFA uses a harvesting scope to follow the vein like a road map and to prevent flaps and devitalized tissue. The diameter of the vein is noted at various levels. This technique allows the FWFA to make the initial incision directly over the course of the vein. Skin flaps caused by making the incision to the right or left of the vein, shallow underlying tissue dissection, and inappropriate dissection into the deep recess of the leg are avoided completely. Current noninvasive venous testing methods provide precise information about the anatomic and physiologic changes discovered in the venous system.

The use of ultrasound for determining blood flow depends on the Doppler principle, which f i s t was described in the mid-nineteenth century when the apparent change in frequency of sound or light waves emitted or reflected from a moving object was noted.I4 When a moving interface (eg, red blood cells) travels toward the ultrasound beam, the reflected waves seemingly increase in frequency. In actuality, the frequency of transmission does not change, but the waves are packed together as the object moves toward the beam of sound. Conversely, the reflected waves’ frequencies decrease as blood travels away from the beam. The apparent change in frequency is called the Doppler shift and is proportional to the velocity of the moving blood. Ultrasound is used for vascular testing in two ways. The most common technique is to determine venous blood flow by using a Doppler. This technique is similar to sonar or radar and determines blood flow by measuring the difference between transmitted and reflected ultrasound waves. Another common method is to use ultrasonography to determine topographic anatomy. Ultrasonography procedure two-dimensional images are displayed on a tele-vision screen by analyzing the collected reflections of millions of ultrasound waves transmitted through the skin. Most ultrasound instruments contain a hand-held probe. The probe is fitted with piezoelectric crystals. When energized by an electric current, piezoelectric crystals vibrate, creating sound waves. Conversely, piezoelectric crystals produce an electrical current

Figure 4 The greater saphenous vein as seen on ultrasound.

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when stimulated by an external force. Another set of crystals in the probe is designated as the receiver. As the ultrasound energy is transmitted through the tissue by the sending crystal, some is dissipated, some refracted, and some reflected back to the receiving crystal. The receiving crystal is excited by the reflected waves causing it to vibrate, which in turn, creates an electrical current. The current is processed by the instrument and reported in a variety of forms. An aqueous coupling gel is placed on the skin, and the scrub person places the probe in the gel for better penetration of sound waves through the skin surface because sound waves are poorly transmitted through the air. The instrument processes reflected ultrasound signals. The signal is represented acoustically and can be converted to an optical or graphic format. The process of examining a particular area of the blood vessel with the ultrasound beam is termed insinuation or interrogation. It has long been noted that invasive monitoring is the most accurate manner of blood pressure monitoring in that it offers the clinician a beat by beat assessment of the pressure. An example of the use of ultrasound in monitoring is the pressure wave form. The up slope of the pressure wave form relates to and shows the movement of myocardial contractility. At the point of the highest degree of contractility, the slope peaks. Arrhythmias and their hemodynamic consequences are recognized easily, pressure changes with respiration indicate volume status, and an indwelling arterial catheter facilitates frequent

Figure 5

measurements of blood chemistry. The fist attempt to establish intraarterial access usually is performed by direct cannulation of the artery with a catheter. The radial artery is the most commonly cannulated vessel because the ulna artery usually provides less than 90% of all blood flow to the hand. The Allen’s test evaluates adequate collateral flow through the ulnar artery with the radial artery occluded. There are many indications for placing an arterial catheter, including major procedures with large fluid shifts; intracranial and cardiac procedures; patients with severe cardiovascular diseases, dysrhythmias, or chronic obstructive pulmonary disease; procedures requiring hypotensive technique; massive trauma, or shock; thoracic surgery; abdominal aneurysms; patients requiring frequent blood sampling; or patients whose blood pressure cannot be measured noninvasively (ie, patients who are morbidly obese or bum victims). Most ultrasound devices on the market today are equipped with a depth marker, power, and gain. Minimal technical training is required, and use of the devices can be learned within minutes. Arteries can be distinguished from veins in the transverse scan because of the collapsing property of the vein when pressure is applied by the scanning probe; pulsatile vessels also are identified more easily (Figure 5). Two sizes of probes (ie, 7.5 MI&, 9 MHz) are the standard. The probe tip is equipped with a built-in mechanical standoff that moves the ultrasonic transducer away from the surface, allowing for sharp focus and detail

The radial artery as seen on ultrasound.

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8

Figure 6 The left coronary artery bulb as seen on ultrasound.

of structures very close to the device tip. The 9 MHz probe provides greater resolution. A snap-on clip that attaches to the center of the probe and acts as a guide for the exploring needle is included. After the vessel is seen on the screen, the passage of the needle can be seen on the screen. The needle renders an acoustic showing that is present in the form of a vertical line. The device also may be used as an epiaortic ultrasound probe in preventing stroke during cardiac surgery. Aortic wall plaques in the ascending aorta are easily distinguishable, thus preventing cross clamp placement, which would disturb these plaques. Aortic valves and leaflets also may be identified. This offers the surgeon a chance to examine the aortic valve in those cases of sclerosis without stenosis where the cardiologist is not sure of the tightness of the valve. The surgeon also can see the just completed aortic valve prosthesis in real time. Although the mitral valve cannot be reached with the currently marketed probe, the bicuspid easily is seen, as is the atrial septum. The frequency of surgical technique modification due to aortic plaque discovered by epiaortic ultrasound is approximately 20%.15 Saphenous vein mapping is done quickly and noninvasively. The ultrasound device locates and maps the vein, allowing the RNFA to find veins in any patient’s leg. With this preoperative examination, the RNFA may decide which vein segment is too small or too large or eliminate legs with dual systems or absent veins. This saves time exploring a leg in which the vein is not adequate for grafting. In mini-

mally invasive and endoscopic vein harvesting, the RNFA can locate the saphenous vein at the knee within a few seconds and know exactly where to make the incision and how deep the main vein lies. For open vein harvesting, knowing the exact course of the vein reduces the tendency to create flaps and improves wound healing. When coronary arteries are not clearly visible or palpable, the ultrasound device may be used to locate these vessels (Figure 6).This is especially true for an intramyocardial left anterior descending (LAD) artery. By using the ultrasound device intraoperatively to more readily locate coronary arteries, the patient is spared extended cardiopulmonary perfusion pump time and surgery. CASE glvW

h4r K is a 76-year-old man with coronary artery disease. Right and left heart catheterization with coronary angiography revealed serial lesions of the LAD artery, which had a 90% blockage, as did the circumflex artery. The first obtuse marginal branch of the circumflex artery (OM-1) had a 60% blockage, the right circumflex artery (RCA) was 70% to 80% blocked, and the distal right coronary branch had a 70% to 80% stenosis with a normal ejection fraction of 60%. Eight years earlier, Mr K had a myocardial infarction, after which he developed a significant ventricular arrhythmia. Mr K underwent electrophysiologic ablation of those arrhythmias. This was followed by treatment with long-acting beta-blocker

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medication. The plan was to perform five CABGs using the left internal mammary artery to revascularize the LAD artery and using saphenous vein grafts for the remaining vessels. Mr K arrived in the preoperative holding area for insertion of IV lines and prepping of surgical sites. The RNFA reviewed the patient's chart carefully and checked his current medical complaints, past medical and surgical history, informed consent, and all diagnostic test results. The circulating nurse and FWFA met with Mr K and family members before surgery and explained the perioperative process. They answered questions for the patient and his family members. The RNFA gave a brief review of the procedure, explained what the patient and family members could expect postoperatively, and explained the expected times necessary for the procedure, recovery, and length of stay. The patient was taken to the OR suite, placed on the OR bed, and offered comfort measures. First the anesthesia care provider used the ultrasound device to locate the internal jugular for central line and pulmonary artery catheter line placement. By applying conductive gel to the inside of the sterile probe sleeve, the anesthesia care provider maintained a sterile field for line insertions. The probe was used to locate and identify the different vessels of the neck (Figures 7, 8, and 9). Each was identified according to position, relationship to other vessels, and structure integrity. With a small amount of pressure applied by the ultrasound probe, the anesthesia care provider was able to identify veins as well as arteries. The collapsing quality of the veins was noticeable readily, and the arteries remained somewhat more intact and slightly inflexible. A small amount of plaque in the carotid artery also was discovered. After locating the jugular vein, the anesthesia care provider held the position of the probe while inserting the 18-g locating needle. The needle is identified easily, and the anesthesia care provider moved the needle into the jugular vein. With blood return in the needle, the anesthesia care provider proceeded with the usual wire placement, catheter insertion, and pulmonary artery catheter placement. When Mr K was anesthetized, the RNFA placed a padded bolster under his thighs to assist with proper positioning and access for vein harvesting. The RNFA placed conductive gel and the ultrasound device on the patient's right thigh, midway between the knee and groin. The RNFA selected the initial search site from his or her past experience and

Figure 7 * Right carotid artery bulb as seen on ultrasound.

a

Figure 9

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Right common carot'd artery as Seen on

Right Carotid artery as seen on ultrasound.

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knowledge of anatomical landmarks. Immediately, the ultrasound device identified internal structures. The device identified depth markers on the screen, which allowed the RNFA to determine the depth and lumen size of the vein. This helped identify appropriately sized veins with no abnormalities. Additionally, veins located in an extremely shallow position in the tissues pose a safety risk. If the RNFA has foreknowledge of saphenous vein position, extra care can be used during harvest to avoid accidental injury to the vessel. The RNFA marked the skin at the location of the vein with an indelible marker and moved the probe either proximally or distally to follow the vein. The saphenous vein was observed easily on the ultrasound device’s screen. Following the vein, the RNFA continued to mark the patient’s skin every 5 cm with the skin marker noting the direction and distance. The RNFA also was able to mark distinguishing characteristics (eg, branches, varicosities). The RNFA watched for branching veins that give the appearance of a widening or elongation of the main vein and, within millimeters, move away from the main vein. The RNFA marked the direction of these branches for harvest purposes. The RNFA also was alert for the presence of varicosities and noticed if the vein structure changed significantly, which indicates a large, distorted vessel. The RNFA marked the skin location of these varicosities to avoid traumatic injury when harvesting the vein. The RNFA easily noted the depth and size of the vein because of the depth markers incorporated into the ultrasound device screen. This allowed the RNFA to measure the vein’s depth in the tissue and prevent inadvertent injury. The RNFA calculated the size of the vein by using the on-screen markers and noted which portion of the vessel was the appropriate size. This eliminated exploring for a vein that was poorly sized and prevented Mr K from receiving an extended incision or additional incisions on another donor site. The RNFA used different skin marking symbols to distinguish size changes in the vein and repeated these steps on the opposite leg and other possible donor sites. The RNFA marked donor sites already prepared. When additional or alternative sites were not required, the marks were removed at the end of the procedure. The RNFA used the ultrasound device on the sterile field to reconfii the vein’s direction during harvest. Sterile sleeves and gel were used during the procedure. By inserting the gel into the sleeve and fit-

ting it over the ultrasound probe, the device helped the RNFA redirect the harvest without making additional incision sites or creating skm flaps and trauma. After the heart was exposed, the surgeon used the ultrasound device as an epiaortic probe to identify plaque locations. By locating these sites before applying cross clamps, the risk of breaking off small particles of plaque (ie, atheromas) is greatly diminished. Alternate cross clamp sites then could be located. The RNFA also used the ultrasound device for femoral line placement. When the radial arterial line could not be located easily, the RNFA located the femoral vessels for femoral arterial line placement. To do this, the RNFA placed sterile gel in the end of the sterile sleeve, placed the probe in the sleeve, and placed the probe in the groin area with a small amount of pressure. When vessel structures were located, the RNFA decreased and increased pressure alternately to distinguish veins from arteries. An aspirating needle attached to a 10-mL syringe was directed by the probe’s needle guiding tip and inserted in the vessel at approximately a 45-degree angle. The vessel wall showed a slight depression just before the needle penetration. With the aspiration of arterial blood, the RNFA proceeded with the line placement in the usual manner. The RNFA harvested the saphenous vein without incident, irrigated the leg wound with antibiotic solution, inserted a 19-Fr drain in the incision site from the upper thigh to just above the knee, and closed Mr K’s leg using 2-0 and 3-0 polyglactin suture on a curved atraumatic needle for the deeper subcutaneous tissues and 3-0 polyglycolic acid or polyglactin suture on a cutting needle for the skin. The RNFA then assisted the surgeon with the anastomosis of the grafts to the coronary arteries. The left internal mammary artery (LIMA) was anastomosed to the LAD artery while the OM-1 and circumflex arteries each were grafted with saphenous vein segments. The right coronary artery and distal right coronary artery were grafted sequentially with another segment of saphenous vein. Mr K was weaned from cardiopulmonary bypass, and the surgeon removed the cannulae. After protamine was administered to reverse the heparin, the surgeon inserted two 28-Fr chest tubes from the subxyphoid into the mediastinal space. The surgeon attached pacing wires to the ventricle and atrium and closed the sternum with #5 stainless steel wire and the subcutaneous layers with #1 polyglycolic suture. The subcuticular layer was closed with 3-0 polyglycolic suture.

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Dressings were applied to the chest and graph site incisions. Mr K was transferred to an intensive care unit (ICU) bed, and his chest tubes were connected to drainage systems. The anesthesia care provider, the RNFA, and the circulating nurse transferred Mr K to the ICU directly from the OR. The patient was monitored with ECG, pulse oximetry for oxygen saturation, and radial arterial line pressure and ventilated with an Ambu bag with oxygen at a flow of 10 L per minute. Mr K was placed on a ventilator on arrival in the ICU. The anesthesia care provider, RNFA, and circulating nurse gave the ICU nurses reports concerning Mr K’s condition. The RNFA also wrote a progress note concerning the procedure and orders for postoperative care. The ICU nurses assessed Mr K’s level of pain, vital signs, pacing wires, and drainage from chest tubes; administered medications as ordered; and checked his dressings. Mr K was weaned from the ventilator within four hours of his arrival in the ICU, and nurses removed his invasive monitoring lines at that time. They transferred Mr K to the surgical floor on his second postoperative day. The remainder of Mr K’s postoperative course was uneventful, with chest tubes, pleural drains, and pacing wires removed on the third postoperative day. He was discharged on postoperative day five and seen in the cardiothoracic clinic a week later. The surgeon discharged Mr K from care a month later. The use of the ultrasound device saved Mr K extended vein harvesting incisions and anesthesia NOTES 1. “Centers for Disease Control

and Preventioflational Centers for Health Statistics and the American Heart Association, National Health and Nutrition Examination Survey III ( ” E S III) 1998-1994.” Available from http://www.americanheart.o&atistics/biostats/biohbp. htm. Accessed 25 April 2000. 2. R K Grooters, N Hiroshi, eds, Alternative Bypass Conduits and Methodr for Surgical Coronary Revascularization ( b o n k ,I W Futura Publishing, 1994) 13. 3. M M Levinson, “Intraoperative monitoring during cardiac surgery: Some observations,” The Heart Surgery Forum no 1999-2858 (May 1,1999) 111-114.

time. By using the ultrasound device, the surgeon located a grade 11 plaque in the ascending aorta approximately 4 cm from the arch. Although this location was not in the immediate cross clamp site, it was noted and avoided. CONCLUSION

The use of the ultrasound device provides a safer surgical procedure for cardiothoracic patients. New and more technically challenging surgical procedures require advanced equipment. With a relatively low capital cost, use of this device can help prevent long hospital stays, infections, hematomas, and strokes. Each of these complications represents a tremendous cost to the patient, hospital, and medical system. With the use of minimally invasive surgical techniques to remove the saphenous vein, ultrasound devices will become standard equipment in the cardiac setting. These minimally invasive techniques are less painful and have fewer complications than conventional procedures used to harvest veins. Patients no longer are satisfied with a second and often painful surgical site resulting in a long scar. The RNFA will need to learn more advanced techniques to locate and harvest vessels for cardiac revascularization. By doing so, the RNFA will be able to offer the patient a safer, less costly, and more efficient method of care. A

Rod Heckman, RN, MBA, CRNFA, CNOR, is a cardiac first assistant at Hutchinson Hospital, Hutchinson, Kan.

4. P Amarenco et al, “The prevalence of ulcerated plaques in the aortic arch in patients with stroke,” New England Journal of Medicine 326 (Jan 23, 1992) 221-225. 5. Grooters, Hiroshi, eds, Alternative Bypass Conduits and Methodsfor Surgical Coronary Revascularization, 13. 6. Levinson, “Intraoperative monitoring during cardiac surgery: Some observations,” 111-114. 7. T Z Hayward, lII, et al, “Endoscopic versus open saphenous vein harvest: The effect on postoperative outcomes,” Annals of Thoracic Surgery 68 (December 1999) 21072111. 8. Grooters, Hiroshi, eds, Alternative Bypass Conduits and

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Methodsfor Surgical Coronary Revascularization,13. 9. T D Bartley et al, “Aortocoronary bypass grafting with multiple sequential anastomoses to a single vein,” Archives of Surgery 105 (December 1972) 915-917. 10. Ibid. 11. Ibid. 12. Hayward, III, et al, “Endoscopic versus open saphenous vein harvest: The effect on postoperative outcomes,” 2107-2111. 13. Ibid. 14. L L Tretbar, VenousDisorders of the Legs: Principles and Practice (London: Springer-Verlag, 1999) 41. 15. Levinson, “Intraoperative monitoring during cardiac surgery: Some observations,” 111-114.