Minneapolis Veterans Administration Medical Center Research Articles

Risk of acute kidney injury in patients who undergo coronary angiography and cardiac surgery in close succession

Cardiac surgery and coronary angiography are both associated with risk of acute kidney injury (AKI). We hypothesized that the risk of post-operative AKI increases when coronary angiogram and cardiac surgery are performed in close succession, without sufficient time for recovery from the adverse effects of intravenous contrast. We included 2133 consecutive patients who underwent cardiac surgery at the Minneapolis Veterans Administration Medical Center from 2004 to 2010. Acute kidney injury was defined by the AKI network and the risk, injury, failure, loss, end-stage (RIFLE) criteria. Patients were 66 ± 10 years old. Mean pre-operative creatinine and estimated glomerular filtration rate were 1.1 ± 0.4 mg/dL and 75 ± 22 mL/min/1.73 m(2), respectively. Cardiac surgery was performed 14 days (range 0-235) after coronary angiography. Acute kidney injury occurred in 680 (32%) patients per AKI network, 390 (18%) patients per RIFLE risk, and 111 (5%) patients per RIFLE injury criteria. Age, body mass index, diabetes mellitus, New York Heart Association class III/IV, cardiopulmonary bypass time, and impaired pre-operative renal function were independent predictors of AKI. However, time between coronary angiogram and cardiac surgery was not a predictor (P = 0.41). AKI occurred in 35% of 433 patients operated within 3 days of coronary angiogram vs. 31% of 1700 patients operated after 3 days (P = 0.17). Results were the same in patients with impaired pre-operative renal function and those with contrast-induced nephropathy. Risk of AKI after cardiac surgery is not influenced by the time between coronary angiogram and cardiac surgery. These results do not support the notion of delaying cardiac surgery for the sole purpose of renal recovery after coronary angiogram.

Abstract 9401: Risk of Acute Kidney Injury is Not Higher in Patients Who Undergo Coronary Angiography and Cardiac Surgery in Close Succession

Background Cardiac surgery and coronary angiography are both associated with higher risk of acute kidney injury (AKI). We hypothesized that the risk of postoperative AKI increases when coronary angiogram and cardiac surgery are performed in close succession, without sufficient time to allow kidney function to recover from the adverse effects of intravenous contrast. Methods We included 2133 consecutive patients who underwent cardiac surgery at the Minneapolis Veterans Administration Medical Center from 2004 to 2010. The outcome variable was AKI as defined by the AKI network (increase in creatinine >0.3 mg/dl or >50% from baseline 48 hours after surgery or hemodialysis) and the Risk, Injury, Failure, Loss, End-stage (RIFLE) criteria. Estimated glomerular filtration rate (eGFR) was calculated by the Modification of Diet in Renal Disease (MDRD) method. Multivariable logistic regression analysis was used. Number of days between coronary angiogram and cardiac surgery was analyzed as a continuous variable. Results Patients were 66±10 years old. Mean preoperative creatinine and eGFR were 1.1±0.4 mg/dl and 75±22 ml/min/1.73 m 2 , respectively. Cardiac surgery was performed after a median 14 days (range 0-235) following coronary angiography. Of the 2133 patients, 680 (32%) met the AKI network definition, and 390 (18%) and 111 (5%) met the RIFLE risk and injury criteria of AKI, respectively. Age, body mass index, diabetes mellitus New York Heart Association class III/IV, cardiopulmonary bypass time, and impaired preoperative renal function (eGFR < 60 ml/min/1.73m 2 ) were independent predictors of AKI. However, the time between coronary angiogram and cardiac surgery was not associated with AKI in univariable and multivariable analyses. Frequency of AKI was 35% in 433 patients who were operated within 3 days of coronary angiogram vs. 31% in 1700 patients who were operated after 3 days (p=0.17). Results were the same in subgroups of patients with impaired preoperative renal function and those who had contrast-induced nephropathy. Conclusion Risk of AKI after cardiac surgery is not influenced by the time between coronary angiogram and cardiac surgery. There is no need to delay cardiac surgery for the sole purpose of renal recovery after coronary angiogram.

Comparison of Risk Scores to Estimate Perioperative Mortality in Aortic Valve Replacement Surgery

Transaortic valve implantation has recently been introduced as an alternative to aortic valve replacement (AVR) for high-risk patients with aortic stenosis. However, accurate assessment of surgical risk is critical for appropriate patient selection. We compared the accuracy of The Society of Thoracic Surgeons (STS) risk score, the European System for Cardiac Risk Evaluation (EuroSCORE), and the Veterans Administration (VA) risk score in predicting perioperative mortality after AVR. We included 537 consecutive patients who underwent AVR for severe aortic stenosis at the Minneapolis VA Medical Center between 1997 and 2008. Observed and predicted perioperative (30-day) mortality rates were compared. Hosmer-Lemeshow goodness-of-fit test and receiver operating characteristic curves were performed to assess the performance of the scores. Perioperative mortality rate was 5.9% (n=32). Predicted mortality rates for the EuroSCORE, STS score, and VA score were 15.6%, 3.6%, and 6.7%, respectively (p=0.001). The EuroSCORE overestimated mortality in all patients, most notably among those with ejection fraction less than 35% (49% predicted versus 9% observed). The EuroSCORE had poor calibration (goodness-of-fit test p<0.008), whereas the STS and the VA scores were well calibrated. However, all three scores displayed good discrimination characteristics per the areas under the receiver operating characteristic curves: STS score 0.73 (95% confidence interval: 0.69 to 0.77); VA score 0.66 (95% confidence interval: 0.62 to 0.70); and EuroSCORE 0.68 (95% confidence interval: 0.64 to 0.72; p>0.05). The EuroSCORE substantially overestimates perioperative mortality risk in AVR, particularly in patients with low ejection fraction. These data have implications when deciding the appropriate intervention (transaortic valve implantation versus AVR) for high-risk aortic stenosis patients.

Dose-Dependent Effect of Statins on the Incidence of Acute Kidney Injury After Cardiac Surgery

Acute kidney injury (AKI) after cardiac surgery is associated with increased morbidity and mortality. We assessed whether statin treatment is associated with a lower incidence of postoperative AKI in 2,104 consecutive patients who underwent coronary artery bypass graft or valve surgery at the Minneapolis Veterans Administration Medical Center. Acute kidney injury was defined as absolute increase greater than 0.3 mg/dL or relative increase greater than 50% in serum creatinine from baseline, within 48 hours after surgery or requiring postoperative hemodialysis per AKI network. Propensity scores were utilized to adjust for the differences between the statin and the no-statin treatment groups. All statins were converted to equivalent-dose simvastatin and divided at the median to construct high-dose (≥40 mg) and low-dose (<40 mg) statin groups. Of the 2,104 patients, 1,435 (68%) were taking statins (638 high-dose) and 495 (24%) developed AKI (25% high-dose vs 40% low-dose vs 35% no-statin; p = 0.014). Estimated preoperative glomerular filtration rate (p = 0.003), diabetes mellitus (p=0.02), valve surgery with or without coronary artery bypass graft (p = 0.024), cardiopulmonary bypass time (p = 0.001), and intraaortic balloon pump (p = 0.055) were independent predictors of AKI. After propensity adjustment statin treatment was not associated with postoperative AKI (odds ratio 0.79; 95% confidence interval 0.59 to 1.06; p = 0.11 for high-dose v. no-statin). After full adjustment for all independent predictors of AKI, the results did not change. Statins also had no effect on the incidence of postoperative hemodialysis (0.8% high-dose vs 1.9% low-dose vs 1% no-statin; p = 0.15). Statin treatment is not associated with a lower incidence of AKI after cardiac surgery.

Long‐Term Mortality and Pacing Outcomes of Patients with Permanent Pacemaker Implantation after Cardiac Surgery

Approximately 20,000 permanent pacemakers (PPMs) are implanted annually for bradycardia or atrioventricular (AV) block after cardiac surgery. Little is known about the long-term pacing and mortality outcomes and the temporal trends of these patients. We examined 6,268 consecutive patients who underwent cardiac surgery at the Minneapolis Veterans Administration Medical Center between 1987 and 2010. Patients who had a PPM within 30 days of cardiac surgery were identified. Pacemaker interrogation records were retrospectively reviewed and mortality was ascertained. Overall, 141 (2.2%) patients underwent PPM implantation for high-degree AV block (55%) and bradycardia (45%), 9 ± 6 days after surgery. Age, diuretic use, cardiopulmonary bypass time (CPBT), and valve surgery were independent predictors of PPM requirement. After 5.6 ± 4.2 years of follow-up, 40% of the patients were PPM dependent. Longer CPBT (P = 0.03), PR interval >200 ms (P = 0.03), and QRS interval > 120 ms (P = 0.04) on baseline electrocardiogram predicted PPM dependency . In univariable analysis, PPM patients had a higher long-term mortality than those without PPM (45% vs 36%; P = 0.02). However, after adjusting for age, sex, type of surgery, and CPBT, PPM requirement was not associated with long-term mortality (hazard ratio 1.3; 95% confidence interval 0.9-1.9; P = 0.17). Compared to before, incidence of PPM implantation increased after the year 2000 (1.9% vs 2.6%; P = 0.04). The majority of patients who require PPM after cardiac surgery are not PPM dependent in the long term. Requiring a PPM after surgery is not associated with long-term mortality after adjustment for patient-related risk factors and cardiac surgical procedure.

The A, B, BI, and Cs ofClostridium difficile

The study by Belmares et al (1) is the most comprehensive, longitudinal study of the molecular epidemiology of Clostridium difficile infection to date. This study is impressive not only because restriction endonuclease analysis typing was performed on three-quarters of C. difficile isolates from 908 cases of C. difficile infection (CDI) at the Minneapolis Veterans Administration Medical Center (MVAMC) collected over a 10 year period, but also because the investigators recognized the importance of conducting this study despite the 18 year time span from the collection of the C. difficile isolates to publication. This study confirms what other less systematic and/or comprehensive studies have suggested, the molecular epidemiology of C. difficile in healthcare facilities is frequently both diverse and dynamic (2–8). This study must be interpreted in conjunction with knowledge of the other studies performed and activities that took place during the same time period at the MVAMC that may have affected C. difficile transmission (9–15). Infection control policies, changes in healthcare delivery, and interventions that took place over the 10 year period included: 1) placing patients with CDI in private rooms only if incontinent and unable to use a bedpan, 2) using a quaternary ammonium disinfectant for cleaning all hospital rooms, 3) authorizing nurses to send diarrheal stool for C. difficile testing without a physician order, 4) restricting the use of clindamycin starting September 1985, 5) donning gloves as the standard for handling all body fluids starting April 1988, and 6) moving all patients into a new building in June 1988. Although this study contributes significantly to our knowledge of C. difficile, it also highlights the need for more studies combining molecular epidemiology with CDI prevention efforts in order to understand the effectiveness of CDI prevention practices.

Restraining the “One-Point Restraint”? Foley Catheter Use Improvement Efforts at Minneapolis Veterans Administration Medical Center (MVAMC)

ISSUE: Foley catheters are useful tools in health care; however they can also harm patients (pt) by causing infection, discomfort, trauma, restraint, and loss of dignity. Unfortunately, Foleys are used inappropriately, as documented in the literature and observed at MVAMC. Providers are unaware which of their pt have a Foley in place, and these “forgotten Foleys” are apt to be clinically non-indicated. Problems identified included verbal orders for Foleys without a Computerized Patient Record System (CPRS) order and Foleys not removed despite an order to discontinue (d/c).

Validation of a Risk Score for Dying Within 1 Year of an Admission for Heart Failure

Background Development of heart failure greatly reduces life expectancy. Accurate estimates of the risk of dying are needed in clinical practice and for risk adjustment in observational studies. A relatively simple risk score has been developed to determine the risk of dying within 1-year of an admission for heart failure. We wanted to evaluate the risk score's predictive validity. Methods and Results Data were abstracted from the electronic medical records of 769 patients admitted to the Minneapolis Veterans Administration medical center with a primary diagnosis of heart failure. Mortality within 1 year of admission was 25%. The c-index for the risk score was 0.71 (95% confidence interval 0.67–0.76). Similar to the original derivation cohort, mortality in risk score groups was 7% for a score lower than 60 (n = 44), 14% for 61 to 90 (n = 246), 26% for 91 to 120 (n = 222), 51% for 121 to 150 (n = 106), and 50% for scores greater than 150 (n = 8). Conclusion A previously developed risk score for 1-year mortality after an admission for heart failure provided a moderate degree of discrimination in a validation cohort from a different setting. Mortality in risk score groups was consistent with the original patient cohort. These results support the validity of the risk score and its application to a different patient population.

Recent quitters' interest in recycling and harm reduction

Many smoking cessation attempts are followed by failure or relapse. The optimal time to initiate a new quit attempt is not known. Administrative databases documenting recent use of a pharmacological aid for smoking cessation provide access to a population of smokers recently in the action phase of quitting. This study describes interest in further treatment among this population. A total of 2,340 smokers from the Minneapolis Veterans Administration Medical Center received prescriptions for a smoking cessation aid during an 18-month period. We conducted a cross-sectional survey of a random sample of this population a minimum of 3 months following the prescription, using a structured telephone interview (N=391). The response rate was 75.8%. The 1-month point-prevalent abstinence rate was 19.7%. Of continuing smokers, 98% were willing to make another quit attempt--50% immediately, and 28% within 1 month. There was no relationship between time since the last quit attempt and interest in trying again immediately. Some 95% of continuing smokers were willing to try a reduction strategy. Of these, 82.7% were interested in using nicotine replacement therapy (NRT) to accomplish this goal. Most cessation programs do not systematically approach participants who relapse. These data suggest that this population would welcome further help in quitting or reducing smoking shortly following failure, and that smokers do not commonly relapse to a precontemplation stage of change.

Impervious wound-edge protector to reduce postoperative wound infection: a randomised, controlled trial

Surgical wound infections are a major source of postoperative morbidity and additional cost of postoperative care. During a 10-year infection-surveillance programme at Minneapolis Veterans Administration Medical Center in the USA, there was a 2·5% overall postoperative wound infection rate, consistent with previous reports.1 Davey et al report an additional cost of US$2106 per patient with a postoperative wound infection after colonic surgery.2 It has been shown that the use of a plastic wound drape does not reduce wound contamination or infection.

Haloperidol treatment of behavioral disturbances in alzheimer patients : M.W. Dysken, S.S. Skare, L. Holden, and G. Vatassery. Geriatric Research, Education, and Clinical Center (GRECC), Minneapolis Veterans Administration Medical Center, One Veterans Drive, Minneapolis, MN 55417, USA

Haloperidol treatment of behavioral disturbances in alzheimer patients : M.W. Dysken, S.S. Skare, L. Holden, and G. Vatassery. Geriatric Research, Education, and Clinical Center (GRECC), Minneapolis Veterans Administration Medical Center, One Veterans Drive, Minneapolis, MN 55417, USA

Toward Smoke-Free VA Hospitals

To the Editor. — The letter by Drs Joseph and Korn 1 in the Sept 16 issue of JAMA discusses the attitudes of veterans toward smoking restrictions in a Veterans Administration (VA) hospital and the feasibility of smoke-free VA hospitals. We were encouraged and delighted to hear that the Minneapolis VA Medical Center has become a totally smoke-free hospital. All other VA hospitals, on the other hand, still allow smoking by patients and staff in a number of areas. The number of places where smoking is allowed in the Denver VA Medical Center has been reduced significantly in the last few years, but further efforts to restrict smoking have met with considerable resistance. To determine the extent of this resistance among patients, we gave a questionnaire (June through August 1987) to outpatients awaiting primary care clinic appointments. Completed questionnaires were received from 84% (468/553); 40% were current smokers, 45% were

Characterization of a nosocomial Clostridium difficile outbreak by using plasmid profile typing and clindamycin susceptibility testing.

The mean number of cases of Clostridium difficile diarrhea at the Minneapolis Veterans Administration Medical Center increased to 17.3 per month in June-August 1985, compared with 7.1 per month in the previous 17 mo. Plasmid profiles and clindamycin susceptibility were used as markers to evaluate the increase in cases. Ninety clindamycin-resistant and 22 clindamycin-susceptible isolates of C. difficile from 1985 were examined for plasmids. A clindamycin-resistant organism contained a cryptic plasmid of 3.1 kilobases (kb). None of the clindamycin-susceptible isolates contained the 3.1-kb plasmid, as compared with 40 of 90 clindamycin-resistant isolates (P less than .005). Restriction endonuclease digestion and Southern blot hybridization were used to confirm the identity of the 3.1-kb plasmid between strains. Isolates retained clindamycin resistance after plasmid curing. It could not be determined if the organism responsible was an indigenous C. difficile strain that acquired a plasmid or was a new strain introduced from outside the hospital.

Assessment and Treatment of the Elderly Neuropsychiatric Patient

This book constitutes the fourth volume in an outstanding series edited by a Minneapolis Veterans Administration Medical Center neurologist and Baylor University neuropsychologist. One reason that the previous volumes were so well done was that they were focused:<i>The Aging Nervous System, Behavioral Assessment and Psychopharmacology</i>, and<i>The Aging Motor System</i>. A lack of focus plagues the present volume, which should have been titled<i>An Introduction to Geriatric Psychiatry</i>. Chapters cover intake and assessment of dementia, with an emphasis on medical laboratory workups (Larson and Featherstone), neuroleptic indications and side effects (Dysken, Miles, and Schenck), antidepressants (Janowsky), psychodynamic psychotherapy (Newton and Lazarus), family therapy (Maletta), cognitive psychotherapy (Gallagher and Thompson), psychosocial and environmental milieus (Bourstrom, Chock, and Rosenberg), bereavement (Gallagher), and Belgian health care provision (Baro and Dom). This reviewer has several criticisms of this present volume. First, although most of the authors are authorities within their respective areas, there is little that is new in this volume, for the authors have made their points before

In vitro activity of efrotomycin, ciprofloxacin, and six other antimicrobials against Clostridium difficile

The susceptibility of 69 clinical isolates of Clostridium difficile from the Minneapolis Veterans Administration Medical Center and 29 C. difficile strains from other hospitals to efrotomycin, ciprofloxacin, and six other antimicrobials was tested in vitro by agar dilution. Ciprofloxin (MIC 50 and MIC 90 = 8 mcg/ml) was only moderately active whereas efrotomycin (MIC 50 = 0.125, MIC 90 = 0.25 mcg/ml) was highly active against C. difficile .

Frequency of aminoglycoside 6'-N-acetyltransferase among Serratia species during increased use of amikacin in the hospital

The incidence of tobramycin-resistant, gentamicin-susceptible Serratia species at the Minneapolis Veterans Administration Medical Center decreased from an average 42.1 to 2.5% (P less than 0.001) during a 4.5-year period despite the predominant use of amikacin. These organisms were shown to express a 6'-N-acetyltransferase-modifying enzyme (EC 2.3.1.82). Resistance was not shown to be plasmid mediated.

Resistance surveillance programs and the incidence of gram-negative bacillary resistance to amikacin from 1967 to 1985

Data relating to amikacin resistance among gram-negative bacilli were obtained by means of a review of published literature and resistance surveillance studies. Data from the first several years of amikacin use are difficult to interpret because the 10-μg disk used for Kirby-Bauer susceptibility testing resulted in apparent greater resistance than the present 30-μg disk. A large United States susceptibility surveillance program that monitors antibiotic use has shown a trend since 1977 of greater susceptibility of Serratia species and greater resistance among Pseudomonas aeruginosa for all the aminoglycosides. Pseudomonas resistance to amikacin has shown the smallest increase of any aminoglycoside. Several hospitals (Strong Memorial Hospital, University of Maryland Cancer Center, and Minneapolis Veterans Administration Medical Center) have reported either no significant change or a decrease in resistance to amikacin when it was the most frequently used aminoglycoside. In a large, 14-center, prospective study, high-level use of amikacin resulted in a significant decrease in resistance to gentamicin and tobramycin (p <0.01) and a marginal increase (p <0.05) in amikacin resistance. Significantly increased amikacin resistance has been reported from two institutions, neither of which used amikacin as the predominant aminoglycoside. Overall, the high-level use of amikacin in large multi-center surveillance programs for as long as five years has not resulted in a significant increase in amikacin resistance rates at any of the individual institutions surveyed.

Hospital distribution, persistence, and reintroduction of related gentamicin R plasmids.

A single plasmid clone was predominantly responsible for gentamicin resistance at the Minneapolis Veterans Administration Medical Center (MVAMC) for 9 years, although two unrelated R plasmids were found. Epidemiological data and restriction endonuclease analysis of 25 plasmid isolates suggested that the clonally derived plasmid population had persisted at the hospital. However, one case of reintroduction of the original epidemic plasmid from a hospital in another state was documented 4 years after the introduction of the original plasmid to the MVAMC. Resistance by the clonally derived plasmid population was not localized geographically within the MVAMC but rather was a hospital-wide problem. Furthermore, previously described classes of DNA rearrangement of the original plasmid were also widely disseminated in the hospital, implying that spread of strains bearing index-related plasmids was relatively unimpeded within the MVAMC despite extensive barrier isolation and cohorting measures. Potential environmental reservoirs of the plasmids were identified in hospital sinks and drains, but their relation to continued patient infection is not known.

Preoperative endoscopic retrograde cholangiopancreatography in the surgical management of pancreatic pseudocysts

Preoperative ERCP was performed on 39 patients treated surgically for pancreatic pseudocysts from 1970 to 1982 at the Minneapolis Veterans Administration Medical Center. ERCP-related sepsis was rare (4 percent of patients) and only occurred when surgery was delayed for more than 24 hours. The primary benefit of preoperative ERCP was to provide detailed information on pancreatic and biliary ductal anatomic characteristics other than those specifically related to the pancreatic pseudocyst. These data influenced the choice of operation in 49 percent of the patients. Specific preoperative surgical planning was facilitated and intraoperative pancreatography and cholangiography were obviated. Major postoperative complications occurred in 21 percent of the patients (0 percent mortality) but none were considered to be related to preoperative ERCP. ERCP before operation is a safe and important adjunct to surgical management of pancreatic pseudocysts. We strongly believe, however, that the interval from ERCP to surgery should not exceed 24 hours.

Aminoglycoside resistance in gram-negative bacilli during increased amikacin use: Comparison of experience in 14 United States hospitals with experience in the Minneapolis Veterans Administration Medical Center

Resistance to amikacin, gentamicin, and tobramycin was surveyed prospectively during controlled aminoglycoside usage in 14 hospitals. Following an initial baseline period (minimum, three months) during which gentamicin use predominated, gentamicin and tobramycin were placed on restrictive control, establishing amikacin as the aminoglycoside of general use (86 percent of total aminoglycoside usage). During an average of 35 months' restriction of gentamicin and tobramycin, significant reductions in gram-negative resistance to gentamicin (8.4 to 7.0 percent, p <0.001) and tobramycin (6.0 to 5.3 percent, p <0.01) were observed. The most significant decreases in resistance to gentamicin and tobramycin (p <0.001) were found for Pseudomonas aeruginosa, Klebsiella species, Serratia species, and Proteus species. Amikacin resistance among gram-negative bacilli was observed to increase marginally from 1.4 to 1.7 percent (p <0.05) during the surveillance period, primarily due to a significant increase in resistance among P. aeruginosa (3.0 to 3.9 percent, p = 0.05). These data were compared with data from a similar surveillance program at the 700-bed Minneapolis Veterans Administration Medical Center. Over a period of 54 months, both gentamicin and tobramycin resistance decreased significantly when amikacin was used (p <0.001), then increased with reintroduction of gentamicin (p <0.05), and decreased significantly with reintroduction of amikacin (p <0.001). Despite predominant amikacin use for a total of 38 months, amikacin resistance did not increase and actually decreased significantly (p <0.05) in the last 12 months.