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Vol. 23, No. 1, JANUARY 2006


Practice Alert:Deep Vein Thrombosis Prevention


The goal of the AACN Practice Alerts is to help nurses and other healthcare practitioners carry their bold voices to the bedside to directly impact patient care. Practice Alerts are directives from AACN that are supported by authoritative evidence to ensure excellence in practice and a safe and humane work environment.

Expected Practice
• Assess all patients upon admission to the ICU for risk factors of deep vein thrombosis (DVT) and anticipate orders for DVT prophylaxis based on risk assessment. Clinical eligibility and regimens for DVT prophylaxis include:

o Moderate-risk patients including medically ill and postoperative patients—on low dose unfractionated heparin or low-molecular-weight heparin (LMWH)
o Higher risk patients including major trauma or orthopedic surgery—LMWH
o Patients with high risk for bleeding—on mechanical prophylaxis including graduated compression stockings and/or intermittent pneumatic compression devices
o Mechanical prophylaxis may also be anticipated in conjunction with anti-coagulant based prophylaxis regimens.

• Review daily with the physician and during multidisciplinary rounds each patient’s current DVT risk factors including clinical status, necessity for central venous catheter (CVC), current status of DVT prophylaxis, risk for bleeding, and response to treatment.

• Maximize patient mobility whenever possible and take measures to reduce the amount of time the patient is immobile because of the effects of treatment (eg, pain, sedation, neuromuscular blockade, mechanical ventilation).

• Ensure that mechanical prophylaxis devices are fitted properly and in use at all times except when being removed for cleaning and/or inspection of skin.

Supporting Evidence
• Multiple medical and surgical risk factors leading to DVT formation have been identified.1 Iatrogenic risk factors for DVT include immobilization, sedation/neuromuscular blockade, CVCs, surgery, sepsis, mechanical ventilation, vasopressor administration, heart failure, stroke, malignancy, previous DVT, and renal dialysis; a vast majority of patients in critical care units have 1 or more major risk factors.1-4 In 5 prospective studies, the rate of DVT in patients in critical care not receiving prophylaxis ranged from 13% to 31%.5-8 Because signs and symptoms of DVT are frequently silent and can lead to fatal pulmonary embolism, AHRQ (Agency for Healthcare Research and Quality) and ACCP (American College of Chest Physicians) recommend DVT prophylaxis for at-risk patients.1,9-17

• Randomized trials indicate that both low dose unfractionated heparin and LMWH are efficacious in preventing DVT in moderate-risk critical care patients.5-8, 18 For patients at higher risk, such as those who have major trauma or have had orthopedic surgery, LMWH has been shown to provide superior protection over low dose unfractionated heparin.1 Direct thrombin inhibitors can be used in place of low molecular weight heparin or unfractionated heparin for patients with documented or suspected heparin induced thrombocytopenia.1, 19,20 Numerous studies suggest that aspirin alone is not an efficacious means of DVT prophylaxis for any patient group.21-25

• Although examined less rigorously than anticoagulant based methods, mechanical methods of prophylaxis (including graduated compression stockings, intermittent compression devices, and venous foot pumps) have been shown to reduce the risk of DVT.26-36 One study involving non-lower extremity trauma patients compared the efficacy of intermittent pneumatic compression devices and venous foot pumps. DVT rates among the venous foot pump group were 3 times greater when compared with the rates of the intermittent pneumatic compression group. The researchers concluded that intermittent pneumatic compression devices provided superior prophylaxis in this patient population.34

• In general, mechanical prophylaxis is less efficacious when compared to anticoagulation based therapy.31-33, 35,36 Reduction in risk of death or pulmonary embolism has not been attributed to mechanical methods of prophylaxis.1 In 1 study involving below-the-knee graded stockings, 98% of commercially available stockings failed to produce an ideal pressure gradient and 54% were found to produce a dangerous reverse pressure gradient. 37 Mechanical prophylaxis methods are a desirable option because they do not pose bleeding concerns.1 A combination of mechanical prophylaxis and chemoprophylaxis is thought to potentiate overall efficacy but this combination has not been tested in the critical care setting.38

• Written policies for DVT prophylaxis in conjunction with either preprinted or computerized ICU admission orders have been shown to increase compliance with prophylaxis measures. 39 One study found that implementation of a daily goals form, which included DVT prophylaxis in the ICU, resulted in a significant improvement in the percentage of residents and nurses who understood the patient’s daily goals for care and decreased ICU length of stay by 1.1 days.40

• The presence of a CVC is an independent risk factor for upper extremity DVT in the general population.41

• Several studies involving a variety of patient populations with diagnostically confirmed DVT have identified immobility either as a comorbidity or independent risk factor.42-44

• Improperly fitted graduated compression stockings producing a reversed pressure gradient were associated with a statistically significantly higher incidence of DVT compared with stockings that produced a proper gradient.35 Studies evaluating compliance with intermittent pneumatic compression devices demonstrated rates of non-compliance ranging from 22% to 81% in at-risk patients.37,45-46

What You Should Do
• Ensure that your unit has a written policy for DVT prophylaxis that is updated regularly to reflect emerging evidentiary findings in addition to preprinted or computerized ICU admission orders.

• Ensure that your unit has an organized process for developing and communicating patient goals (which include DVT prophylaxis) to members of the multidisciplinary team.

• Establish a process to educate and routinely evaluate all staff in the use of mechanical prophylaxis devices.

• Review orders of patients discharged from the ICU to ensure that transfer orders include a plan for DVT prophylaxis.

• Monitor your unit’s compliance with DVT prophylaxis policies and rates of DVT and pulmonary embolism. Initiate quality improvement initiatives involving a multidisciplinary team as necessary.

Need More Information or Help?
Call the AACN Practice Resource Network at (800) 394-5995, ext. 217. Practice Alerts are available online at www.aacn.org > Clinical Practice.

References
1. Geerts WH, Pineo GF, Heit JA, et al. Prevention of venous thromboembolism: the seventh ACCP conference on antithrombotic and thrombolytic therapy. Chest. 2004;126(Suppl):338S-400S.
2. Geerts W, Cook D, Selby R, et al. Venous thromboembolism and its prevention in critical care. J Crit Care. 2002;17,95-104.
3. Cook D, Attia J, Weaver B, et al. Venous thromboembolic disease: an observational study in medical-surgical intensive care unit patients. J Crit Care. 2000;15,127-132.
4. Cook DJ, Crowther M, Meade M, et al. Deep venous thrombosis in medical-surgical ICU patients: prevalence, incidence and risk factors [abstract]. Crit Care. 2003;7(Suppl):S54.
5. Cade JF. High risk of the critically ill for venous thromboembolism. Crit Care Med. 1982;10:448-450.
6. Fraisse F, Holzapfel L, Couland JM, et al. Nadroparin in the prevention of deep vein thrombosis in acute decompensated COPD. Am J Respir Crit Care Med. 2000;161:1109-1114.
7. Kapoor M, Kupfer YY, Tessler S. Subcutaneous heparin prophylaxis significantly reduces the incidence of venous thromboembolic events in the critically ill [abstract]. Crit Care Med. 1999;27(Suppl):A69.
8. Goldhaber SZ, Kett DH, Cusumano CJ, et al. Low molecular weight heparin versus minidose unfractionated heparin for prophylaxis against venous thromboembolism in medical intensive care unit patients: a randomized controlled trial [abstract]. J Am Coll Cardiol. 2000;35(Suppl):325A.
9. Lindblad B, Eriksson A, Bergqvist D. Autopsy-verified pulmonary embolism in a surgical department: analysis of the period from 1951 to 1968. Br J Surg. 1991;78:849-852.
10. Sandler DA, Martin JF. Autopsy proven pulmonary embolism in hospital patients: are we detecting enough deep vein thrombosis? J R Soc Med. 1989;82:203-205.
11. Geerts WH, Heit JA, Clagett GP, et al. Prevention of venous thromboembolism. Chest. 2001;119(Suppl):132S-175S.
12. Prevention of fatal pulmonary embolism by low doses of heparin; International Multicentre Trial. Lancet. 1975;2:45-51.
13. Sevitt S, Gallagher NG. Prevention of venous thrombosis and pulmonary embolism in injured patients: a trial of anticoagulant prophylaxis with phenindione in middle-aged and elderly patients with fractured necks of femur. Lancet. 1959;ii:981-989.
14. Sagar S, Massey J, Sanderson JM. Low-dose heparin prophylaxis against fatal pulmonary embolism. BMJ. 1975;2:257-259.
15. Halkin H, Goldberg J, Modan M, et al. Reduction of mortality in general medical inpatients by low-dose heparin prophylaxis. Ann Intern Med. 1982;96:561-565.
16. Collins R, Scrimgeour A, Yusuf S, et al. Reduction in fatal pulmonary embolism and venous thrombosis by perioperative administration of subcutaneous heparin: overview of results of randomized trials in general, orthopedic, and urologic surgery. N Engl J Med. 1988;318:1162-1173.
17. Agency for Healthcare Research and Quality. Making health care safer: a critical analysis of patient safety practices. Evidence Report/Technology Assessment No. 43. Available at: http://www.ahrq.gov/clinic/ptsafety/. Accessed December 9, 2005.
18. Iorio A, Agnelli G. Low-molecular-weight and unfractionated heparin for prevention of venous thromboembolism in neurosurgery: a meta-analysis. Arch Intern Med. 2000;160:2327-2332.
19. Heit JA. The potential role of direct thrombin inhibitors in the prevention and treatment of venous thromboembolism. Chest. 2003;124(Suppl):40S-48S.
20. DiNisio M, Middeldorp S, Buller HR. Direct thrombin inhibitors. N Engl J Med. 2005; 353:1028-1040.
21. Pulmonary Embolism Prevention Trial. Prevention of pulmonary embolism and deep vein thrombosis with low dose aspirin. Lancet. 2000;355:1295-1302.
22. Butterfield WJ, Hicks BH, Ambler AR, et al. Effect of aspirin on postoperative venous thrombosis. Lancet. 1972;2:441-445.
23. McKenna R, Galante J, Bachmann F, et al. Prevention of venous thromboembolism after total knee replacement by high-dose aspirin or intermittent calf and thigh compression. BMJ. 1980;280:514-517.
24. Powers PJ, Gent M, Jay RM, et al. A randomized trial of less intense postoperative warfarin or aspirin therapy in the prevention of venous thromboembolism after surgery for fractured hip. Arch Intern Med. 1989;149:771-774.
25. Westrich GH, Sculco TP. Prophylaxis against deep venous thrombosis after total knee arthroplasty: pneumatic planter compression and aspirin compared with aspirin alone. J Bone Joint Surg Am. 1996;78:826-834.
26. Coe NP, Collins RE, Klein LA, et al. Prevention of deep vein thrombosis in urological patients: a controlled, randomized trial of low-dose heparin and external
pneumatic compression boots. Surgery. 1978;83:230-234.
27. Turpie AG, Hirsh J, Gent M, et al. Prevention of deep vein thrombosis in potential neurosurgical patients: a randomized trial comparing graduated compression stockings alone or graduated compression stockings plus intermittent pneumatic compression with control. Arch Intern Med. 1989;149:679-681.
28. Vanek VW. Meta-analysis of effectiveness of intermittent pneumatic compression devices with a comparison of thigh-high to knee-high sleeves. Am Surg. 1998;64:1050-1058.
29. Warwick D, Harrison J, Glew D, et al. Comparison of the use of a foot pump with the use of low-molecular-weight heparin for the prevention of deep-vein thrombosis after total hip replacement. J Bone Joint Surg Am. 1998;80:1158-1166:
30. Agu O, Hamilton G, Baker D. Graduated compression stockings in the prevention of venous thromboembolism. Br J Surg. 1999;86:992-1004.
31. Freedman KB, Brookenthal KR, Fitzgerald RH, et al. A meta-analysis of thromboembolic prophylaxis following elective total hip arthroplasty. J Bone Joint Surg Am. 2000;82:929-938.
32. Westrich GH, Haas SB, Mosca P, et al. Meta-analysis of thromboembolic prophylaxis after total knee arthroplasty. J Bone Joint Surg Br. 2000;82:795-800.
33. Amarigiri SV, Lees TA. Elastic compression stockings for prevention of deep vein thrombosis [abstract]. Cochrane Database Syst Rev. Available at: http://www.update-software.com/abstracts/ab001484.htm. Accessed December 9, 2005.
34. Elliot CG, Dudney TM, Egger M, et al. Calf-thigh sequential pneumatic compression compared with plantar venous pneumatic compression to prevent deep-vein thrombosis after non-lower extremity trauma. J Trauma. 1999;47(1):25-32.
35. Hull RD, Raskob GE, Gent M, et al. Effectiveness of intermittent pneumatic leg compression for preventing deep vein thrombosis after total hip replacement. JAMA. 1990;263:2313-2317.
36. Blanchard J, Meuwly JY, Leyvraz PF, et al. Prevention of deep-vein thrombosis after total knee replacement: randomised comparison between a low-molecular-weight heparin (nadroparin) and mechanical prophylaxis with a foot-pump system. J Bone Joint Surg Br. 1999;81:654-659.
37. Best AJ, Williams S, Crozier A, et al. Graded compression stockings in elective orthopaedic surgery: an assessment of the in vivo performance of commercially available stockings in patients having hip and knee arthroplasty. J Bone Joint Surg Br. 2000;82:116-118.
38. Geerts WH, Selby R. Prevention of venous thromboembolism in the ICU. Chest. 2003;124(Suppl):357S-363S.
39. Levi D, Kupfter Y, Seneviratne C, et al. Computerized order entry sets and intensive education improve the rate of prophylaxis for deep vein thrombophlebitis [abstract]. Chest. 1998;114(Suppl):280S.
40. Pronovost P, Berenholtz S, Dorman T, Lipsett PA, Simmonds T, Haraden C. Improving communication in the ICU using daily goals. J Crit Care. 2003;18(2):71-5.
41. Heit JA, Silverstein MD, Mohr DN, et al. Risk factors for deep vein thrombosis and pulmonary embolism: a population-based case-control study. Arch Intern Med. 2000;160:809-815.
42. Goldhaber SZ, Tapson VF. Prospective registry of 5,451 patients with ultrasound confirmed deep vein thrombosis. Am J Cardiol. 2004;15;93(2):259-62.
43. Weill-Engerer S, Meaume, S, Lahlou A, et al. Risk factors for deep vein thrombosis in inpatients aged 65 and older: a case-control multicenter study. J Am Geriatr Soc. 2004;52(8):1299-304.
44. Landefeld CS, McGuire E, Cohen
AM. Clinical findings associated with acute proximal deep vein thrombosis: a basis for quantifying clinical judgment. Am J Med. 1990;88(4):382-8.
45. Cornwell EE, Chang D, Velmahos G, et al. Compliance with sequential compression device prophylaxis in at-risk trauma patients: a prospective analysis. Am Surg. 2002;68:470-473.
46. Comerota AJ, Katz ML, White JV. Why does prophylaxis with external pneumatic compression for deep vein thrombosis fail? Am J Surg. 1992;164:265-268.


AACN Beacon Award Recipients Shine Through


The latest recipients of the Beacon Award for Critical Care Excellence have been announced. Achieving the designation are:

• Intensive Care Unit, Munroe Regional Medical Center, Ocala, Fla.
• Medical Intensive Care Unit, University Hospitals of Cleveland, Cleveland, Ohio
• Medical Intensive Care Unit, Lynchburg General Hospital, Lynchburg, Va.
• Adult Intensive Care Unit, Dartmouth Hitchcock Medical Center, Lebanon, N.H.
• 7200 CCU, Duke University Hospital, Durham, N.C.
• MSICU, Harrisburg Hospital, Harrisburg, Pa.
• Intensive Care Unit, Baptist Hospital East, Louisville, Ky.
• CCU, Piedmont Hospital, Atlanta, Ga.
• SICU-TCCU, Grant Medical Center, Columbus, Ohio
• CCU/OHICU, Grant Medical Center, Columbus, Ohio
• CCU, Mount Carmel West, Columbus, Ohio
• MSICU, Inova Fairfax Hospital, Falls Church, Va.

The AACN Beacon Award gives national recognition to units that exhibit high standards for overall quality and exceptional patient care in healthy, humane and healing work environments. In the application process, units are asked to assess themselves in six areas: recruitment and retention, education, training and mentoring, evidence-based practices, patient outcomes, healing environments, and leadership-organizational ethics. These assessments are then evaluated on a quarterly basis. Awards are granted twice a year.
“We hope the most recent Beacon units inspire other units across the United States to use the Beacon Award mechanism to measure their progress against evidence-based, national criteria for high standards in patient care and work environment,” said Debbie Brinker, RN, MSN, CCRN, CCNS. “Congratulations to this group of recipients. You are an inspiration to
others to achieve this level of excellence.”

AACN membership is not required to apply for or receive the Beacon Award. Applications must be submitted online. Complete application information and requirements are available at www.aacn.org > Beacon Award.

The Credentialing Portfolio Helps APNs Organize Paperwork


By Ellen M. Prewitt, RN-BC, MSN, CCRN, ARNP
Advanced Practice Work Group

As advanced practice nurses gain acceptance, their need to obtain credentials and acquire privileges will increase. With the intention of ensuring safe healthcare to the public, various federal and state agencies have developed criteria shaping the credentialing process that must be met by licensed independent practitioners, such as APNs.

To meet these criteria, APNs must obtain two components from hospitals and other payers: credentialing, which is the process of verifying licensure, certification and education, and privileging, which defines the services the licensed independent practitioner seeks permission to perform. For APNs to be considered, credentialing documentation must support the privileges requested. As APNs become eligible to receive reimbursement for professional services, they will need to more frequently complete credentialing forms requesting privileges. To make the process easier and to eliminate gaps in the ability to provide service, APNs should maintain a structured file or portfolio of important documentation. Organizing this valuable information makes completing paperwork easier. Sample folders are explained below.

Education
One of the first folders should be “Educational Information.” In this folder, include dates of school attendance, transcripts, copies of diplomas, and addresses and phone numbers of schools of nursing attended. These documents are typically submitted only with the initial application to each hospital or agency. Institutions verify the information and keep it on file. Therefore, it is important to give accurate information. If APNs attended an educational institution under a different name, such as a maiden name, this information should be included to assist with verification. Educational information does not need to be resubmitted when renewing institutional credentialing, a process that happens at least biannually.

Licensure
A “State/Federal Licensure” folder should include the RN license, advanced practice license, certificate to prescribe and Drug Enforcement Agency documentation when applicable. If a list of collaborating physicians is submitted to the state board of nursing, keeping a current copy in this folder is wise. Also important is correspondence with the state board of nursing that informs of changes in the collaborating physicians list. Copies of any license must have “copy” written across them, along with the APN’s signature. It is also recommended that APNs write the date of expiration for both state licensure and DEA on the folder, along with the amount of lead time they will need to complete the renewal process. This step will serve as a quick reminder of when to start the institutional credentialing renewal.

Certification
A “National Certification” folder should include a copy of the wallet card or certificate. Again, including the date of renewal on the folder will help APNs remember to seek renewal. Most certification organizations require that applications be submitted a minimum of 60 days prior to expiration of the current certification. If the state in which an APN is practicing requires a current national certification to practice as an advanced practice nurse, keeping certification current is necessary to prevent lapses. A copy of the application submitted should always be kept in the file.

Care Agreement
If the state in which the APN is licensed requires a “Standard Care Arrangement,” a folder should be designated for this document. Many states require that this agreement be reviewed and re-signed annually. This is another important date that needs to be recorded. When APNs renew their institutional credentialing, a copy of a current standard care arrangement, including signatures, must be submitted.

Insurance
A “Liability Insurance” folder should include the policy and current statement of coverage. Documentation on any issues that involve liability should also be included.


Employment
An “Employment History” folder includes the name of each employer with dates of hire, address and phone number, and name of department hired under for each separate employer. This folder should also include a list of other institutions where the APN has privileges, with addresses and phone numbers. If the APN’s name has changed, be sure to list the last name at the time of employment. A copy of applications for credentialing and delineation of privileges request forms can be kept here as well.

Health
A “Health Information” folder includes copies of health forms and immunization records, including last tetanus, rubella immunity, hepatitis B vaccinations and TB testing results.

Curriculum Vitae
A “Curriculum Vitae” folder includes a current curriculum vitae and source documents to assist in any updates. As articles are published or lectures given, APNs can add a copy of the article, flyer on the lecture, thank-you letter for the lecture or other documentation to the folder.

CEU Credit
A “CEU” folder includes certificates for CEUs obtained. A copy of CEU requirements for state licensure and for national certification can also be maintained there.

Other
An “Other” folder includes information on other certifications, such as ACLS and BCLS, as well as a list of memberships in professional organizations, and offices held in those organizations. Placing a card at the front of the file listing deadlines for items to be renewed is helpful. (See sample below.)


Renewal ItemDate of ExpirationDeadline for Submittal
RN/APN/CTP8/31/076/30/07
ACNP
DEA
12/30/06
6/30/06
10/30/06
3/30/06
ACLS
BCLS
12/15/05
12/05/05
12/15/06
12/05/06
Malpractice Insurance7/06 6/06
Standard care arrangement 7/06 7/06

These folder titles cover most of the information needed to ensure organization of the documents needed for credentialing. By maintaining these files, the task of completing applications for initial and renewal credentialing will be less stressful and more efficient.

Bibliography
Hravnak M, Baldisseri M. Credentialing and privileging: Insight into the process for acute care nurse practitioners. AACN Clin Issues. 1997;8:108-115.
Kamajian MF, Mitchell SA, Fruth RA. Credentialing and privileging of advanced practice nurses. AACN Clin Issues. 1999;10: 316-336.
Klein CA. The scoop on credentialing. The Nurse Practitioner. 2003;28:54.
Joint Commission on Accreditation of Healthcare Organizations. Medical staff. 2004 Automated CAMH Refreshed Core. Oakbrook Terrace IL: Joint Commission Resources Inc; 2004.


Public Policy Update


AACN Joins Call for Increased Funding
AACN has joined other nursing organizations in signing a letter urging President Bush to increase funding for the Nursing Workforce Development programs authorized by Title VIII of the Public Health Service Act.

“While we acknowledge the fact that the country is facing some severe budget constraints, Title VIII funding is required now to educate and prepare the nursing workforce needed to provide our citizens with nursing care on a daily basis, as well as during major emergencies and disasters,” the letter stated.

The organizations pointed to Hurricane Katrina and the prospect of a pandemic avian flu outbreak as examples of the importance of critical care nurses in responding to major emergencies and disasters.

“Nurses are a vital resource for our nation, and yet federal funding lags far below the need,” the letter continued. “Today’s nursing shortage is very real and very different from shortages in the past.”

The current nursing shortage is further complicated by the fact that schools of nursing continue to suffer from a growing shortage of faculty, which prevents these institutions from admitting more students. According to recent statistics from the National League for Nursing, an estimated 125,000 applications were turned away from nursing programs at all levels for the academic year 2003-2004. Insufficient faculty is the top reason cited by nursing schools for not accepting all qualified applicants into their programs.

Without an infusion of funding that can really make a difference, the nursing and nursing faculty shortages will continue at the expense of the health and well-being of this country’s citizens.

Funding to Nursing Student Loan Programs Should Not Be Cut
The American Hospital Association and eight other healthcare organizations have urged congressional appropriators to protect the Nursing Student Loan and Nursing Education Loan Repayment programs from fiscal year 2006 funding cuts proposed by the president to offset spending on Hurricane Katrina relief. They said the programs provide the primary financial support for nursing education, recruitment and retention to meet the nation’s future healthcare needs. For more information, go to http://www.aha.org/aha/advocacy-grassroots/advocacy/hillletters/2005/051114Hillet_nursingworkforce.html.

OIG Issues Guidance on Part D Patient Assistance Programs
A special advisory bulletin was recently issued by the Health and Human Services Department Office of Inspector General providing guidance on the application of fraud and abuse laws to patient assistance programs (PAPs). These programs offer assistance in obtaining outpatient prescription drugs to financially needy Medicare beneficiaries who enroll in the Medicare Part D drug benefit.

According to the bulletin, arrangements through which a pharmaceutical manufacturer would use a PAP it operates or controls to subsidize its own products that will be payable by Medicare Part D present a heightened risk of fraud and abuse. However, there are other options manufacturers can consider to assist financially needy Part D enrollees in obtaining outpatient prescription drugs, the bulletin notes. For more information, go to http://www.oig.hhs.gov/publications/docs/press/2005/patientassistancesabrelD.pdf

Practice Resource Network


Q:

What is the current practice for correlating arterial blood pressure with manual blood pressures?

A:

Invasive arterial blood pressure monitoring is a direct method of measuring blood pressure. It is accomplished by inserting a cannula in the radial, femoral or dorsalis paedis artery and connecting it to a zeroed and calibrated transducer that converts pressure energy into electrical signals. It is considered the "gold standard" of blood pressure monitoring, provided the technical factors are optimal. The technical factors include appropriate leveling and zeroing; intact system integrity; optimal dynamic response characteristics; and absence of artifact.1 Indirect methods of measuring blood pressure include palpation, auscultation and oscillotonometry.

There is no absolute relationship between the two different measurements, because they follow different laws of physics and physiology.2 Direct methods measure pressure and indirect methods measure flow; therefore, different results should be expected. In addition, differences occur because the location of measurement used is generally not identical in both methods (brachial artery for manual blood pressure vs. radial artery for invasive arterial pressure monitoring). More specifically, correlation between the indirect (oscilloscope) and the arterial pressure monitoring system is not a gauge for the proper functioning of the pressure monitoring system.3

Q:

How do you assess the arterial monitoring system for accuracy?

A:

An optimally damped system is needed to reproduce waveforms without distortion for accurate reproduction of the arterial pressure. This is assessed by performing a dynamic response test (square wave test). The AACN arterial pressure monitoring protocol recommends that this response test is done every eight to 12 hours, whenever the system is opened to air (after zeroing) and whenever the accuracy of pressure measurement is in question.1

Both the AACN Procedure Manual ( #128150) and Protocols for Practice: Arterial Pressure Monitoring ( #170701) include figures and descriptions of how to perform a dynamic response test.1,4

References
1. Imperial-Perez F, McRae M. AACN Protocols for Practice: Arterial Pressure Monitoring. American Association of Critical-Care Nurses. Aliso Viejo, Calif. 1998.
2. McGhee BH, Bridges EJ, Monitoring arterial blood pressure: What you may not know. Crit Care Nurse. 2002;22(2):60-79.
3. Bridges EJ, Middleton R. Direct arterial vs. oscillometric monitoring of blood pressure: stop comparing and pick one (a decision-making algorithm), Crit Care Nurse. 1997;17(3): 58-97.
4. Lynn-McHale Wiegand D. Carlson K. AACN Procedure Manual for Critical Care. 5th ed. Elsevier Inc. St. Louis, Mo. 2005.

Do you have a practice question? Call the AACN Practice Resource Network at (800) 394-5995, ext. 217.
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