Clinical application of perioperative evidence-based practice.

Practitioners today are seeing changes in our health care system, economic pressures related to decreased reimbursement, and the growth of managed care that are producing major adjustments in health professions' education, patient care, and research. Evidence-based practice (EBP) is considered by many to be the way of the future. This article describes factors affecting implementation of EBP in the clinical arena. It also gives some practical applications found when implementing EBP at one hospital.

An evidence-based evaluation of intradialytic parenteral nutrition.

Malnutrition is a well-recognized comorbid condition in dialysis patients that contributes to the increased mortality seen in these patients. Multiple interventions have been tried in an effort to decrease mortality. The most controversial of these is intradialytic parenteral nutrition. In an era of high costs and shrinking budgets, it is important to critically examine published data to determine the quality of the data and to determine whether the reported results are valid and clinically applicable. Using an evidence-based approach, all published literature concerning intradialytic parenteral nutrition was reviewed, quality of the data determined, number needed to treat (NNT) calculated, and potential costs of treatment determined. Twenty-four studies that met the search criteria were identified. Only three studies were randomized; one of these was a feasibility study, and the other two were only of level B quality. The remaining studies were either case reports or observational studies of level C quality. The absolute risk reduction in mortality with intradialytic parenteral nutrition (IDPN) usage ranged from 0.12 to 0.65; relative risk reduction ranged from 0.48 to 0.74; NNT ranged from 2 to 17; cost ranged from $150,000,000 to $877,500,000; and 588 to 9,750 patients might be expected to experience a decrease in mortality. The results of this review indicate that the data supporting the use of IDPN are weak and a clear recommendation cannot be made. IDPN use in hemodialysis patients seems to be associated with decreased mortality. IDPN should be available for use in patients who meet previously published guidelines and who are not normoalbuminemic.

The effect of changing the total parenteral nutrition order form on resident physician ordering behavior.

The quality assurance process at Scott and White Hospital, Temple, Texas, identified a marked variation in total parenteral nutrition (TPN) prescriptions compared with recommendations by the Nutrition Support Service (NSS). A TPN order form with additive guidelines was designed to assist physicians in ordering TPN specific to patient needs. The effect of the change was assessed by comparing 50 TPN patients using the old form (1990) with 50 patients for whom the new form (1992) was used. The groups demonstrated no difference in demographics, mortality, length of stay, or biochemical parameters and were reflective of all TPN patients treated (1990, n = 280; 1992, n = 392). A significant decrease was noted in overfeeding of kilocalories when resident orders were compared with NSS recommendations (125% +/- 24% versus 110% +/- 29%, p = .017; and amino acids (120% +/- 32% versus 105% +/- 29%, p = .071, mean +/- SD). This resulted in a decrease of 8% in the cost of delivering a patient-day of TPN. We conclude that changing the TPN order form to a teaching vehicle results in decreased overfeeding and costs.

Intradialytic parenteral nutrition: a useful therapy?

Malnutrition in hemodialysis patients is common and may affect as much as 40% of this population of patients. There are many causes of malnutrition and all must be considered before utilizing nutrition support to reverse the malnutrition. Intradialytic parenteral nutrition (IDPN) is a therapy that has become popular among US nephrologists despite the fact that there are no clear data that support its use or efficacy. A thorough review of published articles suggests a relationship between the use of IDPN and improved patient outcome measured by hospitalization rate and a decrease in mortality in certain subgroups. However, these studies have many confounding factors that prevent a definitive conclusion concerning the true efficacy of IDPN. This is very problematic since reimbursement changes for parenteral and enteral nutrition have been proposed by HCFA. The best recommendation that can be made for IDPN is that it may represent a useful form of nutrition support in the malnourished hemodialysis patient who has no other active disease processes, cannot ingest adequate nutrition by mouth, and has a contraindication to or a serious complication from enteral feeding. It is clearly not a therapy to be considered as the first line of nutrition support in these patients.

Comparison of four bedside indicators used to predict duodenal feeding tube placement with radiography.

The validity of four indicators to predict successful duodenal feeding tube placement was evaluated in a prospective trial. Data were collected on each indicator at prepyloric (< or = 65 cm) and postpyloric (> or = 75 cm) feeding tube lengths. Feeding tubes were placed in 106 patients. Eighteen feeding tubes were located in the stomach, and 88 were in the duodenum. Auscultation (progression of loudest sound locations from the left to the right abdomen) had a positive predictive value of 85% (negative predictive value, 31%). The vacuum effect (a change from 40 mL of aspirated air to < or = 10 mL after 60 mL of air instillation) had a positive predictive value of 86% (negative predictive value, 45%) and was significantly correlated with duodenal placement (p = .02). Aspirate was present at prepyloric and postpyloric lengths in 35 cases. Ten of these 35 cases had the defined change in pH from < or = 4.0 to > or = 6.0 (positive predictive value, 100%; negative predictive value, 28%). The positive predictive value of color (a change to yellow) was also 100% (n = 11); the negative predictive value was 29%. The low negative predictive values of the indicators suggest that the absence of defined changes is of no assistance in discriminating between stomach and duodenal placement. A positive auscultation or vacuum effect test is not conclusive for duodenal placement. A positive pH or color change test may obviate the need for a confirmatory radiograph.(ABSTRACT TRUNCATED AT 250 WORDS)

Accuracy of enteral pumps: in vitro performance.

There are few data on the accuracy of pumps used to deliver enteral formulas. Enteral pump manufacturers claim that accuracy is within 10% of the selected flow rate. We evaluated 15 pumps: Flexiflo Companion (n = 5), Travenol 2100 (n = 5), and Kangaroo 324 (n = 5). Three types of formula at room temperature were infused at 10, 100, and 300 mL/h. The formulas used were Jevity, Ensure Plus, and Suplena with added Promod. The Flexiflo Companion and Kangaroo 324 pumps delivered 90% to 110% of the expected volume using the ready-to-feed formulas. The Travenol 2100 pumps averaged less than 90% of the selected flow rates for the three formulas infused. All three pumps delivered less than 90% of the expected volume using a formula with an added powder, but the Travenol 2100 delivered the highest volume of this same formula. There was no significant difference in the delivery of Jevity with the Flexiflo Companion (104% +/- 5% SD) and the Kangaroo 324 pumps (99% +/- 4% SD), but the flow rate was significantly lower with the Travenol 2100 pumps (80% +/- 6% SD). There was no significant difference in the flow rate of Ensure Plus with the Kangaroo 324 (95% +/- 7% SD) and the Travenol 2100 pumps (89% +/- 4% SD). The flow rate of Ensure Plus with the Flexiflo Companion pumps was significantly higher (107% +/- 4% SD).(ABSTRACT TRUNCATED AT 250 WORDS)

Improved left ventricular contractility with cool temperature hemodialysis.

Cool temperature dialysis (CTD) has been shown to sharply decrease the frequency of intradialytic hemodialysis hypotension, but the mechanism of this hemodynamic protection is unknown. Therefore, we performed two-dimensional echocardiographic studies of left ventricular contractility in six stable hemodialysis patients before and after hemodialysis at 37 degrees C (RTD) and 35 degrees C (CTD). Left ventricular function was assessed by plotting the rate-corrected velocity of circumferential fiber shortening (Vcfc) against end-systolic wall stress (sigma es) at four different levels of afterload. Linear regression was used to calculate Vcfc at a common afterload of 50 g/cm2. Changes in weight and dialysis parameters were similar following RTD and CTD. Mean arterial pressure and heart rate did not change significantly following RTD or CTD. The Vcfc - sigma es relation was shifted upward in each patient after CTD, indicating increased contractility as compared to RTD or pre-dialysis baseline. Pre-dialysis Vcfc at an afterload of 50 g/cm2 was similar during RTD and CTD (0.94 +/- 0.24 circ/sec vs. 0.92 +/- 0.22 circ/sec). Postdialysis Vcfc at an afterload of 50 g/cm2 was significantly higher for CTD than for RTD (1.13 +/- 0.29 circ/sec vs. 0.98 +/- 0.30 circ/sec, P = 0.0004). Thus, cool temperature dialysis increases left ventricular contractility in hemodialysis patients, which may be a potential mechanism whereby hemodynamic tolerance to the dialysis procedure is improved.

The use of cardiopulmonary resuscitation: how nephrologists and internists differ.

We performed a national survey to explore the circumstances under which general internists and nephrologists discuss cardiopulmonary resuscitation (CPR) with patients and the factors influencing physician decisions to open such discussions. We wondered whether nephrology fellowship training and/or formal exposure to an ethics course during training altered physicians' use of CPR. Significantly more nephrologists than internists responded to the study (nephrologists, 174/467; internists, 92/380; P less than 0.01). Few of the respondents participated in an ethics course during training (9% of nephrologists, 15% of internists; P = NS), and fewer than half (26% of nephrologists, 37% of internists; P = NS) had engaged in formal discussions about initiating and withdrawing life-sustaining treatment during their training. Nephrologists spent significantly more time caring for patients in intensive care units (ICUs) (29% v 21% of time, P less than 0.05), and more often discussed CPR during their first meeting with a patient (7% of nephrologists v 1% of internists; P less than 0.05). Twenty-eight percent of nephrologists and 19% of internists thought CPR should be offered to all patients. Both nephrologists and internists rated neurologic dysfunction as the most important and age the least important factor influencing decisions to terminate CPR. Nephrologists were less comfortable than internists with healthy dialysis patients' decisions to refuse CPR. We conclude that nephrologists are more inclined than internists to use CPR in dialysis patients, in patients with impaired functional status, and in all patients. Training in medical ethics did not account for the differences among nephrologists and internists.

Nephrologists' reported attitudes about factors influencing recommendations to initiate or withdraw dialysis.

A nationwide survey of nephrologists was performed to learn which patient factors and characteristics of nephrology fellowship training they reported as influencing their decisions to start or stop dialysis. One hundred seventy-four of 482 responses were received. Most respondents were men in private practice living in large communities (41% in communities over 1,000,000 population). Most had completed a 2-yr fellowship (88%) at a medical school hospital (75%). Few (9%) received formal instruction in medical ethics during fellowship training, and only one quarter had informally discussed life-sustaining treatments during training. Neurological status was the most, and age the least, important patient factor reported to influence decisions to start or stop dialysis. No respondent demographic factors correlated with ranking of patient factors in decisions to initiate or forego dialysis. Family wishes and preexisting medical conditions were significantly more important considerations in initiating than in stopping dialysis. Insights about the factors practicing nephrologists reportedly weigh most heavily in making the difficult decisions to withhold or withdraw dialysis are provided by this study. Additional study of the actual practices of nephrologists in decisions to initiate or withdraw dialysis and the factors influencing those decisions are needed. Formal instruction in these and other ethical problems confronting nephrologists should perhaps be included in fellowship programs.

The utility of a structured evaluation of elderly patients for continuous peritoneal dialysis.

The elderly comprise an increasing proportion of chronic dialysis patients. Recruiting them for continuous peritoneal dialysis (CPD) would help CPD programs maintain a patient population. We retrospectively studied the ability of a prospective evaluation to predict success with CPD in elderly (age greater than 60 years) patients. PD nurses and a renal social worker assigned scores in 10 categories, which were then averaged to obtain an over-all evaluation score. Scores were from 1-5 with 1 = good, 5 = poor, and 3 = average. Thirty-four elderly patients began CPD during the study period. Evaluation scores were available for 28 of these patients before they began dialysis. Evaluation scores less than 3 predicted success with CPD (2.2 +/- 0.2 versus 3.2 +/- 0.4 in patients transferring to hemodialysis, p less than 0.02). Patient motivation and preference were the categories that predicted success with CPD. Elderly patients were more likely than younger patients (those less than 60 years of age) to decline CPD for social reasons (46% versus 4% respectively, p less than 0.001). Elderly patients required more CPD training time than young patients (4.9 +/- 0.7 days versus 3.3 +/- 0.8 days respectively, p less than 0.01). We conclude that a prospective assessment of elderly patients can predict success with CPD and provide information important to individual structuring of CPD training and follow-up.

Use of a silicone dual-lumen catheter with a Dacron cuff as a long-term vascular access for hemodialysis patients.

We evaluated our experience over a 4-year period with a silicone dual-lumen catheter with a Dacron cuff (SDLCDC) to determine if the catheter represents an alternative to the polytetrafluoroethylene graft for long-term vascular access for hemodialysis patients. Records of 131 patients who used 168 catheters were reviewed for catheter function, duration of use, and occurrence and response to treatment of complications. Eighty-five percent of catheters functioned adequately until their use was no longer required or the end of the study. One-year catheter survival estimate was 65% and median survival estimate was 18.5 months. Mean blood flow rate achieved was 243 mL/min and recirculation was 7.5%. Exit-site infection occurred in 21% of patients and bacteremia in 12%. There were significantly more exit-site infections in diabetics than nondiabetics (33% v 11%, P less than 0.02). Exit-site infections resolved with parenteral antibiotic therapy in 90% and bacteremia in 25% of cases without catheter removal. Unresolved bacteremia was the most common cause of catheter removal and led to the loss of 7% of catheters. Thrombotic complications occurred in 46% of catheters. Urokinase instillation successfully treated catheter occlusion in 81% of cases. When urokinase instillation failed, streptokinase infusion restored catheter patency 97% of the time. The literature on the polytetrafluoroethylene (PTFE) graft was reviewed, and the SDLCDC was found to be similar to the graft in function, duration of use, and frequency of infectious and thrombotic complications. We conclude that the catheter represents an alternative to the graft for long-term vascular access in hemodialysis patients. Because of the frequent complications with both accesses, neither should be considered optimal. Further research is required to improve vascular access for patients in whom placement of an arteriovenous fistula is not possible.

Ultrasound as a tool in the diagnosis and management of exit-site infections in patients undergoing continuous ambulatory peritoneal dialysis.

Ultrasonographic examination of the subcutaneous course and exit site of the Tenckhoff catheter in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) was performed to evaluate catheter-related infections. Real-time ultrasound studies were performed in 24 patients with initial exit-site infections; clinically suspected tunnel infections were excluded from analysis. A peri-catheter sonolucent fluid collection, considered a positive study, was demonstrated in 13 ultrasound examinations and tended to be organism-specific; eight of 12 Staphylococcus aureus exit-site infections and three of four gram-negative exit-site infections had positive studies. Only two of seven Staphylococcus epidermidis exit-site infections were initially positive on ultrasound examination. Nine of 13 patients with positive ultrasound studies ultimately lost their catheters to infection despite weeks of parenteral antibiotic therapy and local incision and drainage. There were 11 negative ultrasound studies. Only one of these patients' catheters was lost because of infection. In some episodes of CAPD-associated exit-site infections, especially those caused by S aureus and gram-negative organisms, ultrasound examination of the catheter course may be useful to diagnose unsuspected tunnel infections, direct early therapy, and confirm resolution or persistence of the infections.

Parathyroid hormone and anaemia--an erythrocyte osmotic fragility study in primary and secondary hyperparathyroidism.

Parathyroid hormone (PTH) has been shown in vitro to enhance erythrocyte osmotic fragility (EOF) and has been incriminated as a factor in the anaemia seen in patients with primary hyperparathyroidism and in patients with renal disease and secondary hyperparathyroidism. Enhanced EOF has also been shown in patients with chronic renal failure but did not correlate with PTH levels. We studied a group of patients with primary hyperparathyroidism with and without anaemia, and patients with secondary hyperparathyroidism and anaemia. We found that EOF studies in these patients did not differ from normal control groups and that there was no relation between PTH, EOF, and haematocrit in either study group. We conclude that PTH over a range of concentrations seen in vivo does not affect erythrocyte osmotic fragility or cause anaemia.

Calcium citrate, a nonaluminum-containing phosphate-binding agent for treatment of CRF.

Calcium citrate was evaluated as a dietary phosphate binder in 81 patients with end-stage renal disease. These patients were grouped as follows: Group 1, 43 patients who were treated with calcium citrate; and Group 2 (the control group), 38 patients who were treated with aluminum-containing compounds. Blood chemistries were measured monthly and medications adjusted to maintain the following levels: serum calcium, greater than 9 mg/dl; serum phosphorus, less than 5.5 mg/dl; and total CO2 content, greater than 22 mmol/liter. At the end of the treatment period, the following serum values were obtained in Groups 1 and 2, respectively: calcium, 9.6 +/- 1.2 mg/dl (mean +/- SD) versus 8.9 +/- 0.8 mg/dl (P less than 0.001); phosphorus 5.5 +/- 1.9 mg/dl versus 7.0 +/- 2.3 mg/dl (P less than 0.005); and calcium-phosphate product, 52 +/- 18 versus 61 +/- 21 (P less than 0.05). Differences in alkaline phosphatase, total CO2 content, and C-terminal parathyroid hormone (C-PTH) values were not statistically significant between the two groups. Fifteen patients in Group 1 were then switched to aluminum-containing compounds and chemistries were compared one month later. During calcium citrate therapy, serum calcium was significantly higher, while C-PTH and serum alkaline phosphatase were significantly reduced. No difference was noted in serum phosphorous and total CO2 content. A questionnaire completed by 17 patients in Group 1 documented excellent patient tolerance to calcium citrate. Hypercalcemia (greater than 10.5 mg/dl) was the only significant complication, but only one patient became symptomatic. We conclude that, as a phosphate binder, calcium citrate is at least as effective as aluminum-containing compounds.