In the United States, we are all familiar with the obesity epi-demic. Not only do we deal with health complications associatedwith high BMI, such as diabetes, hypertension, hyperlipidemiaand degenerative joint disease, but also challenges for nursingcare of bariatric patients fromadequate sized gowns, beds,wheelchairs and other equip-ment to proper drug dosing,vascular access and special-ized skin care. There arenumerous studies describingthe risks for postop complications for general surgery patientswith high BMI, but does that translate to cardiac surgery? Youmay be surprised to learn the answer is, “not necessarily.”

Most studies that have looked at the association betweenobesity and CABG risk have mined extensive patient databasesretrospectively. In addition to the U.S., research has also beendone in Saudi Arabia, Canada, and Taiwan. This process is verycomplicated and requires sophisticated data modeling to differ-entiate the effect of BMI separate from the complicationsassociated with weight. For example, are postop wound infec-tions related to diabetes that occurs with obesity, or the obesityand body habitus itself?

Retrospective StudiesBaslaim et al looked at 462 cardiac surgery cases done over

4 years; 147 (32%) had BMI ≥ 30.1 Obese patients were olderand more likely to have diabetes and hypertension. There wasno difference in operative or in-hospital mortality in obesepatients, nor was BMI a predictor of any major complication fromIABP, wound infection, and reoperation to respiratory complica-tions, CVA, renal failure, or ICU / hospital readmission.

Bhamidipati et al reviewed 742 CABG patients who had off-pump surgery over 7 years; 340 (46%) had BMI ≥ 30.2 As withBaslaim et al, BMI did not influence adjusted odds of any com-plication, and risk-adjusted models for mortality were similaramong all BMI. In addition, there was no significant difference inoperative procedure or resource utilization by obese patients.

Thourani et al examined 4247 patients who had valve sur-gery with or without CABG over 8 years; 436 (10%) had BMI ≥35, 2284 (54%) had BMI 25-35, and 1527 (36%) had BMI ≤ 24.3Researchers discovered obese patients had longer pump times,longer crossclamp times, a higher rate of IABP, longer ICU andhospital length of stay. But, there was no increase in in-hospitalmortality. These researchers found significantly greater in-hospi-tal and long-term mortality in those patients with low BMI,regardless of surgical procedure.

Del Prete et al looked at 1163 CABG patients over 10 years;472 (41%) had BMI ≥ 30.4 While obese patients were youngerand less likely to smoke, there was no difference in short- orlong-term risk-adjusted mortality.

Resource UtilizationThree other studies examined resource utilization. Choi et al

compared 56 morbidly obese (BMI ≥ 40) CABG patients with168 matched controls over 10 years at a VA hospital.5 Obesepatients had, on average, 29 minute longer surgery, 1.9 daylonger ICU stay and 4.7 day longer hospital stay. There was nodifference in outcomes. Rough costs for additional OR time arebetween $450 and $1500 (room charge only) and for additionalICU days, $9000. The authors note that Medicare does not con-sider obesity a condition that qualifies for increasedreimbursement.

Turer et al reviewed 22,877 catheterized patients over 18years, separating into three groups: 7737 (34%) had PCI,7258 (32%) had CABG, and 7882 (34%) were managed withmedication alone.6 Across all BMI, CABG had the highest sur-vival. There were 711 (3%) with BMI ≥ 40; in this group 32%had medications only, 43% had PCI and 25% CABG. Eventhose with left main or 3-vessel disease had lower rates ofCABG if they were obese, even though CABG is associatedwith better long-term survival regardless of weight. Theresearchers question whether there is a bias against offeringsurgery to morbidly obese patients, perhaps due to erroneousthinking that it is much riskier.

A Canadian study examined a database of 27,460 personswho had a cardiac cath over 3 years; 6601 (24%) had BMI 18.5-24.9, 11,386 (42%) had BMI 25-29.9, and 9473 (35%) had BMI>30.7 Overweight and obese patients had higher rates of PCIand CABG, but CABG decreased as BMI increased. When BMIwas ≥ 35, there was significantly less PCI or CABG.

At the Cell LevelObesity-related changes include alterations in the vascular

endothelium and changes in ventricular load and efficiency.Adipose tissue acts as an endocrine organ. Persons with BMI ≥25 had significantly higher triglycerides, H/H, and albumin andsignificantly lower levels of adiponectin, high-sensitivity CRP,and NT-proBNP.8 These lower levels may be the mediating fac-tors protecting obese patients. Higher inflammatory mediatorsmay lead to cardiac cachexia, in which nutritional intake doesnot meet the increased metabolic demands of CAD and heartfailure; this exacerbates the catabolic stress of cardiac surgery.In addition, low BMI is associated with greater hemodilution dur-ing bypass and greater postoperative coagulopathy.3

BMI and Cardiac Surgery Risk

Clinical Update is edited by Patricia Carroll, MS, RN-BC, CEN, RRT, andsupported by an educational grant from Atrium Medical Corporation.

Winter 2013

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BMI Classification• Underweight = <18.5• Normal weight = 18.5-24.9 • Overweight = 25-29.9 • Obesity = 30 or greater Source: National Institutes of Health

In the LiteratureSatisfied Nurses = Satisfied Patients

A nurse researcher from the University of Rochester (NY) hasprovided an important analysis of the relationship between patientsatisfaction (n=1532) and the health of the work environment forcritical care nurses (n=671). Overall quality of nursing care was4.5/5 with the highest scores for friendliness and courtesy, followedby willingness to listen to concerns. Comparing 4 ICUs, nurses’favorable perception of the nurse manager correlated to higherpatient satisfaction. This is a must-read to understand the far-reach-ing effects of unit-level nursing leadership – for good or ill.Source: Boev C: The relationship between nurses’ perception of work environ-ment and patient satisfaction in adult critical care. Journal of NursingScholarship 2012;44(4):368-375. PubMed Citation

Where Has That Stethoscope Been?The current issue of the American Journal of Infection Control

has research on pediatric health care providers’ behavior towardstethoscope disinfection. While 79% of those responding agreedthat scopes should be disinfected after each use, only 24% report-ed doing so. This is an interesting examination of why professionalsdo not follow through with actions they believe are optimal practice. Source: Muniz J, et al: Predictors of stethoscope disinfection among pediatrichealth care providers. American Journal of Infection Control 2012; 40: 922-925.PubMed Citation

A Peek in the Crystal BallThe current issue of Nursing EconomicS provides a comprehen-

sive analysis of the readiness of the national nursing workforce forthe challenges and opportunities that will come with the full imple-mentation of the Affordable Care Act. The authors provide resultsfrom the National Survey of Registered Nurses and discuss therelationships between where we are and where we need to be tooptimize the ACA and the 2010 IOM report The Future of Nursing.This is a great preview of what can be positive, exciting changes fornursing practice in the coming years.Source: Buerhaus PI et al: Are nurses ready for health care reform? A decadeof survey research. Nursing Economic$ 2012; 30(6):318-330.

Markers Can Spread InfectionWith increased awareness of wrong site procedures, we mark

areas to confirm the correct site and keep the Joint Commissionhappy. The FDA does not require approval of markers, so facilitiesneed to do a little more homework to determine which type of mark-er is best and then how to use it correctly. The current issue ofOrthopaedic Nursing provides a review of the literature with dos anddon’ts and best practices for optimal skin marking.Source: Driessche AM: Surgical site markers: potential source for infection.Orthopaedic Nursing 2012 31(6):344-347. PubMed Citation

Surgery Tools

The STS Risk Calculator for cardiac surgery is online:http://tiny.cc/a33ipw Enter patient data and the siteautomatically calculates risks relating to the proceduresuch as mortality, length of stay, prolonged ventilation,and renal failure. A PDF of variables and backgroundinformation is here http://tiny.cc/od4ipw

UCLA has a collection of cardiothoracic surgery toolsincluding operative forms, calculators, and educationmodules for adult and congenital surgery athttp://tiny.cc/g83ipw

CTSNet provides a collection of apps for iPhone andiPad at http://tiny.cc/ls3ipw

iMedicalApps is a site dedicated to reviews of apps forApple devices and Android, for and by medical profes-sionals http://www.imedicalapps.com/

Top 10 free iPad apps http://tiny.cc/7m4ipw

Top 20 free iPhone apps http://tiny.cc/7o4ipw

Top 15 Android apps http://tiny.cc/io4ipw

Winter 2013

Called the “obesity paradox,” additional weight is thought toprovide nutritional and metabolic reserves needed to meet themetabolic demands of CABG recovery; the lower levels of inflam-matory mediators also help protect these patientspostoperatively. In fact, higher hsCRP (high sensitivity CRP)preop correlated with adverse events postop.8

Are We Missing Something?Even as our societal focus has been on obesity, researchers

are increasingly looking at low BMI and low serum albumin levelsas greater risks for postoperative morbidity and mortality.3,6,8,9

While studies use different BMI cut-offs (243, 258, or 266), the

increased risk is clear. This is particularly interesting given theNIH uses 18.5 as the marker for underweight. Going forward,researchers will need to clarify if there are differences among lowBMI, malnutrition, hypoalbuminemia, and frailty and which hasthe greatest effect on outcomes.Sources1. Baslaim G, J Bashore, K Alhoroub: Impact of obesity on early outcomes after cardiacsurgery: experience in a Saudi Arabian center. Ann of Thorac and Cardiovasc Surg2008;14(6):369-375. PubMed Citation2. Bhamidipati CM, KA Seymour, N Cohen, R Rolland, KA Dilip, CJ Lutz: Is body massindex a risk factor for isolated off-pump coronary revascularization? J Card Surg2011;26(6):565-571. PubMed Citation3. Thourani VH, WB Keeling, PD Kilgo, et al.: The impact of body mass index on morbid-ity and short- and long-term mortality in cardiac valvular surgery. J Thorac CardiovascSurg 2011;142(5):1052-1061. PubMed Citation4. Del Prete JC, FG Bakaeen, TK Dao, et al.: The impact of obesity on long-term survivalafter coronary artery bypass grafting. J Surg Res 2010;163(1):7-11. PubMed Citation5. Choi JC, FG Bakaeen, LD Cornwell, et al.: Morbid obesity is associated with increasedresource utilization in coronary artery bypass grafting. Ann Thorac Surg 2012;94(1):23-28. PubMed Citation6. Turer AT, KW Mahaffey, E Honeycutt, et al.: Influence of body mass index on the effi-cacy of revascularization in patients with coronary artery disease. J Thorac CardiovascSurg 2009;137(6):1468-1474. PubMed Citation7. King KM, DA Southern, J Cornuz, A Maitland, ML Knudtson, WA Ghali: Elevated bodymass index and use of coronary revascularization after cardiac catheterization. Am J Med2009;122(3):273-280. PubMed Citation8. Sung SH, TC Wu, CH Huang, SJ Lin, JW Chen: Prognostic impact of body massindex in patients undergoing coronary artery bypass surgery. Heart 2011;97(8):648-654.PubMed Citation9. Bhamidipati CM, DJ LaPar, GS Mehta, et al.: Albumin is a better predictor of outcomesthan body mass index following coronary artery bypass grafting. Surgery 2011;150:626-634. PubMed Citation

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