Reading Understanding the Complete Blood Count With Differential

Download Reading Understanding the Complete Blood Count With Differential

Post on 14-Apr-2018

212 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

<ul><li><p>7/27/2019 Reading Understanding the Complete Blood Count With Differential</p><p> 1/22</p></li><li><p>7/27/2019 Reading Understanding the Complete Blood Count With Differential</p><p> 2/22</p><p>marrow, which include disorders such as ane-mia, leukemia, polycythemia, thrombocytosis,and thrombocytopenia. The CBC also evaluatesmedical conditions that secondarily affect theblood and bone marrow resulting in hemato-logic manifestations such as infection, inflam-mation, coagulopathies, neoplasms, and toxicsubstance exposure. In many instances, specificsymptomatology of a medical condition maynot be present and hematologic changes on theCBC may be the only finding present. These</p><p>changes prompt investigation to then identifythe medical condition.</p><p>To foster the understanding of the usefulness ofthe CBC, the function and life cycle of thevarious cells are introduced. Test indications,characteristics, abnormal findings, and applica-tions for the perianesthesia nurse are discussed.</p><p>Screening</p><p>Screening usually refers to testing patients</p><p>who are asymptomatic and have no physicalsigns of disease. However, symptoms or physi-cal signs may be very insensitive indicators ofsome diseases. In the perianesthesia setting, theuse of the CBC as a screening tool constantlyundergoes revision. Factors such as the preva-lence of disease in a population, the medicalandfinancial impact of missing a problem, thecost per problem found, financial reimburse-</p><p>ment, and societal judgments determine whenscreening tests are indicated. Medicare does notsupport the use of the CBC as a screening tool;to be cost effective, the CBC should only be</p><p>ordered when indicated.2</p><p>Indications</p><p>Preoperative evaluation should include a his-tory, a physical examination, laboratory tests,and an assessment of surgical risk to identifycoexisting diseases and complicating condi-tions. To decrease the risk of morbidity andmortality in the perianesthesia setting, the CBCis used to assist with the identification of pa-tients who are at risk for complications of inad-</p><p>equate tissue perfusion during the procedureand those with a possible infectious or inflam-matory process.3,4</p><p>General indications for a CBC that are consid-ered medically reasonable and are accepted byMedicare are as follows:</p><p> The hemogram should be evaluated forany patient with signs, symptoms, orconditions associated with anemia or</p><p>polycythemia. See Table 2 for specifi</p><p>csigns, symptoms, and conditions. The platelet count should be evaluated</p><p>for patients with findings or conditionsassociated with increased or decreasedplatelet production, destruction, or dys-function (Table 2). The platelet count isusually obtained as part of the hemo-gram.</p><p> The WBC differential should be evalu-ated for any patient with signs, symp-toms, or conditions associated with in-</p><p>fections, inflammatory processes, bonemarrow alterations, and immune disor-ders (Table 2). The WBC count has alsobeen recently identified as a possible riskstratification tool for mortality in acutecoronary syndromes.5</p><p> A hemoglobin and hematocrit (H&amp;H)alone may be appropriate if there is onlya need to assess the oxygen-carrying ca-</p><p>Table 1. Complete Blood Count</p><p>WBC 4,500 to 11,000/L</p><p>Differential white cell count See Table 7</p><p>RBC 4.0 to 6.2 million/L</p><p>HctWomen 35% to 47%</p><p>Men 8 to 64 yr 39% to 50%</p><p>Men 65 to 74 yr 37% to 51%</p><p>Hgb</p><p>Women 12 to 16 g/dL</p><p>Men 14 to 18 g/dL</p><p>RBC indices</p><p>Mean corpuscular volume 82 to 93 m3</p><p>Mean corpuscular Hgb 26 to 34 pg</p><p>Mean corpuscular Hgb concentration 31% to 38%</p><p>Platelet count 150,000 to 400,000 L</p><p>Data from Chernecky et al.1</p><p>UNDERSTANDING THE CBC WITH DIFFERENTIAL 97</p></li><li><p>7/27/2019 Reading Understanding the Complete Blood Count With Differential</p><p> 3/22</p><p>pacity of blood before surgery for pa-tients who do not have the previouslylisted signs, symptoms, or conditions(Table 2). The H&amp;H may be helpful in</p><p>the intraoperative and postoperativephase of care to assess and track forblood loss but can be misleading becauseof the intercompartmental fluid shiftsthat occur during surgery and because ofthe dilutional effects of crystalloid ther-apy.</p><p>Specific perianesthesia indications for the CBCalso take into account the level of surgical com-</p><p>plexity for a given procedure. In general, minor</p><p>procedures are those with very low risk of large</p><p>fluid shifts or significant blood loss. Minor pro-</p><p>cedures include soft tissue and eye procedures;</p><p>minor ortho; as well as ear, nose, and throat andurologic procedures, among others. Keep in</p><p>mind that a minor procedure may turn into a</p><p>moderately complex procedure as complica-</p><p>tions are identified or develop. Major proce-</p><p>dures are those that are often prolonged, often</p><p>with high risk of large fluid shifts or signifi-</p><p>cant blood loss. They often involve major body</p><p>cavities. These include major abdominal, vascu-</p><p>Table 2. Signs, Symptoms, and Conditions That May Warrant a CBC or Parts of a CBC</p><p>Hemogram</p><p>(Findings Related to Anemia)</p><p>Hemogram</p><p>(Findings Related to Polycythemia)</p><p>Hemogram</p><p>(Findings Related to Platelet Dysfunction) WBC With Differential</p><p>PallorWeakness</p><p>Fatigue</p><p>Weight loss</p><p>Bleeding</p><p>Acute or suspected blood loss</p><p>from injury</p><p>Hematuria</p><p>Hematemesis</p><p>Hematochezia</p><p>Positive fecal occult</p><p>Neuropathy</p><p>Malnutrition</p><p>Tachycardia</p><p>Known malignancy</p><p>Systolic heart murmurCongestive heart failure</p><p>Dyspnea</p><p>Angina</p><p>Postural dizziness</p><p>Syncope</p><p>Nailbed deformities</p><p>Known malignancy</p><p>Jaundice</p><p>Hepatomegaly</p><p>Splenomegaly</p><p>Lymphadenopathy</p><p>Ulcers of the lower extremities</p><p>FeverChills</p><p>Ruddy skin</p><p>Conjunctival redness</p><p>Cough</p><p>Wheezing</p><p>Cyanosis</p><p>Clubbing of the fingers</p><p>Orthopnea</p><p>Heart murmur</p><p>Headache</p><p>Memory changes</p><p>Sleep apnea</p><p>Weakness</p><p>Pruritus</p><p>DizzinessExcessive sweating</p><p>Massive obesity</p><p>Gastrointestinal bleeding</p><p>Paresthesias</p><p>Myocardial infarction</p><p>Stroke</p><p>Thromboembolism</p><p>Hepatomegaly</p><p>Splenomegaly</p><p>COPD</p><p>Diastolic hypertension</p><p>Congenital heart disease</p><p>Transient ischemic attack</p><p>Visual symptoms</p><p>Gastrointestinal bleedGenitourinary tract bleed</p><p>Bilateral epistaxis</p><p>Thrombosis</p><p>Ecchymosis</p><p>Purpura</p><p>Jaundice</p><p>Petechiae</p><p>Fever</p><p>Heparin therapy</p><p>Suspected DIC</p><p>Shock</p><p>Preeclampsia</p><p>Massive transfusion</p><p>Recent platelet transfusion</p><p>Cardiopulmonary bypassRenal diseases</p><p>Hypersplenism</p><p>Neurologic abnormalities</p><p>Viral or other infection</p><p>Thrombosis</p><p>Exposure to toxic agents</p><p>Excessive alcohol ingestion</p><p>Autoimmunue disorders</p><p>(SLE, RA)</p><p>Hepatomegaly</p><p>Splenomegaly</p><p>Lymphadenopathy</p><p>FeverChills</p><p>Sweats</p><p>Shock</p><p>Fatigue</p><p>Malaise</p><p>Tachycardia</p><p>Tachypnea</p><p>Heart murmur</p><p>Seizures</p><p>Altered consciousness</p><p>Pain such as headache</p><p>Abdominal pain</p><p>Arthralgia</p><p>Odynophagia</p><p>DysuriaRedness/swelling of skin soft</p><p>tissue or joint</p><p>Ulcers of skin or mucous</p><p>membrane</p><p>Gangrene</p><p>Bleeding</p><p>Thrombosis</p><p>Pulmonary infiltrate</p><p>Jaundice</p><p>Diarrhea</p><p>Vomiting</p><p>Opportunistic infections as</p><p>oral candidiasis</p><p>Hepatomegaly</p><p>SplenomegalyLymphadenopathy</p><p>Abbreviations: COPD, chronic obstructive pulmonary disease; DIC, disseminated intravascular coagulation; SLE, systemic lupus erythematosus; RA,rheumatoid arthritis.</p><p>Data from Centers for Medicare and Medicaid Services (CMS). Available at www.cms.hhs.gov/ncd/searchdisplay.asp?NSD_ID61&amp;NCD_vrsn_num1.</p><p>GEORGE-GAY AND PARKER98</p></li><li><p>7/27/2019 Reading Understanding the Complete Blood Count With Differential</p><p> 4/22</p><p>lar, cardiothoracic, orthopedic, gynecologic/urologic, head and neck, and neurologic proce-dures. Levels of surgical complexity from level 1(minor) to level 5 (major) are described in Table3. The American Society of Anesthesiologists(ASA) physical status classification system is an-other tool that can be used to assess the pa-tients current health status and overall periop-erative risk (Table 4). Although imprecise, it is away to predict the patients anesthetic/surgicalrisks. The higher the ASA class, the greater therisks.</p><p>For the patient who is asymptomatic and activewith a reliable benign history and undergoing aminor procedure, an H&amp;H assessment may beall that is necessary or may not be indicated atall. For those patients undergoing major proce-dures, a CBC with platelets should be com-pleted. The CBC is indicated for elderly patients</p><p>(65 years of age) as part of their preoperativeassessment because of the comorbidities associ-ated with this age group as it may uncoverclinical problems that were not picked up onphysical examination.6 Patients classified withan ASA score of 3 or greater should have a CBCbefore their surgical procedure. In addition tothe general indications for CBC in Table 2,situations requiring a CBC before a surgicalprocedure are listed in Table 5.</p><p>Optimally efficient testing entails considerationof a combination of factors including the age,gender, and reliability of the patient; the surgi-cal procedure; and the type of anesthesia beingused. Older or less reliable patients may bemore likely to have an unsuspected abnormalitypicked up by a screening test. Major proce-dures are associated with significant physiologicstress. Existing medical conditions, which may</p><p>Table 3. Levels of Surgical Complexity</p><p>Level 1</p><p> Minimal risk to the patient independent of anesthesia</p><p> Minimally invasive procedures with little or no blood loss</p><p> Often performed in an office setting with the operating room principally for anesthesia and monitoring Includes breast biopsy, removal of minor skin or subcutaneous lesions, myringotomy tubes, hysteroscopy, cystoscopy, fiberoptic</p><p>bronchoscopy</p><p>Level 2</p><p> Minimal to moderately invasive procedure</p><p> Blood loss less than 500 mL</p><p> Mild risk to patient independent of anesthesia</p><p> Includes diagnostic laparoscopy, dilatation and curettage, fallopian tubal ligation, arthroscopy, inguinal hernia repair, laparoscopic lysis of</p><p>adhesions, tonsillectomy/adenoidectomy, umbilical hernia repair, septoplasty/rhinoplasty, percutaneous lung biopsy, extensive super ficial</p><p>procedures</p><p>Level 3</p><p> Moderate to significantly invasive procedure</p><p> Blood loss potential 500 to 1,500 mL</p><p> Moderate risk to patient independent of anesthesia</p><p> Includes hysterectomy, myomectomy, cholecystectomy, laminectomy, hip/knee replacement, major laparoscopic procedures,</p><p>resection/reconstructive surgery of the digestive tract; excludes open thoracic or intracranial proceduresLevel 4</p><p> Highly invasive procedure</p><p> Blood loss greater than 1,500 mL</p><p> Major risk to patient independent of anesthesia</p><p> Includes major orthopedic-spinal reconstruction, major reconstruction of the gastrointestinal tract, major vascular repair without postoperative</p><p>ICU stay</p><p>Level 5</p><p> Highly invasive procedure</p><p> Blood loss greater than 1,500 mL</p><p> Critical risk to patient independent of anesthesia</p><p> Usual postoperative ICU stay with invasive monitoring</p><p> Includes cardiothoracic procedure; intracranial procedure; major procedure on the oropharynx; major vascular, skeletal, neurologic repair</p><p>UNDERSTANDING THE CBC WITH DIFFERENTIAL 99</p></li><li><p>7/27/2019 Reading Understanding the Complete Blood Count With Differential</p><p> 5/22</p><p>be of little concern during a brief and minorprocedure, may cause problems during and af-ter a long and complex surgery. Preoperativeevaluation should reflect this need for an in-creased level of preparedness and monitoring.</p><p>Timing of the CBC</p><p>A CBC completed within 2 months of a proce-dure is acceptable unless a change is suspectedas a consequence of disease, medication, ortreatment. Repeat testing is indicated for abnor-mal results or for patients with normal resultswho have conditions in which there is a con-</p><p>tinued risk for the development of hematologic</p><p>abnormalities.</p><p>Blood</p><p>The average adult has approximately 5.5 L of</p><p>blood, consisting of plasma and cells. Plasmamakes up 55% of the blood components and</p><p>consists of proteins, water, and some waste</p><p>products. Cells, of which there are 3 main</p><p>types, make up the other 45%. They consist of</p><p>(1) WBCs (leukocytes), of which there are sev-</p><p>eral subtypes; (2) RBCs (erythrocytes); and (3)</p><p>platelets (thrombocytes).</p><p>All blood cells are produced in the bone mar-</p><p>row from a mother cell called the pluripotential</p><p>(multipotential) stem cell (PSC). This PSC un-dergoes stages of differentiation until it be-</p><p>comes committed to either the erythrocyte,</p><p>thrombocyte, or one of the leukocyte subtypes</p><p>(Fig 1). Under normal conditions, only mature</p><p>blood cells should be found circulating in the</p><p>blood. Alterations in the production and func-</p><p>tion of these blood cells provide information</p><p>about the patients diagnosis, prognosis, re-</p><p>Table 4. ASA Classification</p><p>Class Description Examples</p><p>1 A normal healthy patient with no systemic illness Healthy with good exercise tolerance</p><p>2 A patient with well-controlled systemic illness, butwithout functional restrictions</p><p>Well-controlled hypertension, diabetes, without systemic effects; noevidence of COPD, anemia, or obesity</p><p>3 A patient with significant degree of systemic effects that</p><p>limits activities</p><p>Controlled heart failure, stable angina, or history of myocardial</p><p>infarction; diabetes with systemic sequela; uncontrolled</p><p>hypertension; morbid obesity</p><p>4 A patient with severe systemic illness associated with</p><p>significant dysfunction and a constant potential threat</p><p>to life</p><p>Unstable angina, symptomatic heart failure, renal failure requiring</p><p>dialysis</p><p>5 A patient in critical condition, who is at substantial risk</p><p>of death within 24 hours with or without operative</p><p>procedure</p><p>Multiple organ dysfunctions, hemodynamically unstable sepsis,</p><p>poorly controlled coagulopathy</p><p>6 A patient declared brain dead undergoing organ removal</p><p>for donor purposes</p><p>E This symbol is added to any of the above classes to</p><p>designate an emergency</p><p>Data from www.asahq.org, www.nurse-anesthesia.com/generalanesthesia.htm, and www.vh.org/adult/provider/anesthesia/proceduralsedation/asapatientclassification.html.Accessed December 2002.</p><p>Table 5. Situations Requiring Preoperative CBCEvaluation</p><p> Abnormal bleeding ( platelets)</p><p> Heavy ETOH use ( platelets) Potentially toxic medications (eg, which cause bone marrow</p><p>depression)</p><p> Infection ( differential)</p><p> ASA score of3</p><p> Vascular surgery</p><p> Anticipate prosthetic device or hardware placement</p><p> Anticipate 500 mL blood loss, invasive monitoring, or ICU (</p><p>platelets)</p><p> Level 4 or 5 surgery</p><p>Abbreviation: ETOH, alcohol.</p><p>GEORGE-GAY AND PARKER100</p></li><li><p>7/27/2019 Reading Understanding the Complete Blood Count With Differential</p><p> 6/22</p><p>sponse to therapies, and their recovery. Thelaboratory procedure that gives us this informa-tion is the CBC.</p><p>Obtaining the Blood Sample</p><p>The blood sample is obtained via venipunctureand is collected in a lavender top tube, which isthe nationally accepted color standard. Theblood sample will remain useable for analysis atroom temperature for up to 10 hours, afterwhich time the sample deteriorates and is not to</p><p>be considered reliable. The blood sample canalso be kept refrigerated and remain useable foras long as 18 hours. The sample should never befrozen. The patient should ideally be at rest for10 to 15 minutes before obtaining the sample.Automated electronic devices perform enumer-ation of the blood cells. Blood cell counts arereported per microliter. Morphology is deter-mined by stained smears.</p><p>The WBC Count With Differential</p><p>The WBC count with differential determinesthe total number...</p></li></ul>