Hyperkalemia in outpatients using angiotensin-converting enzyme inhibitors. How much should we worry?

BACKGROUND: Hyperkalemia is a potentially life-threatening complication resulting from the use of angiotensin-converting enzyme (ACE) inhibitors; data to guide the intensity of monitoring for or responding to hyperkalemia in outpatients are limited. METHODS: Case-control methodological procedures were used to identify risk factors for hyperkalemia. Outpatients prescribed ACE inhibitors during 1992 and 1993 at a Veterans Affairs medical center general medicine clinic were identified. Case patients had a potassium level higher than 5.1 mmol/L on the day of clinic visit while using an ACE inhibitor; controls had a potassium level lower than 5.0 mmol/L on the day of clinic visit while using an ACE inhibitor and had no elevated potassium level during the study period. Predictor variables measured included type and dosage of ACE inhibitor; serum chemistries; comorbidities; concurrent drug use; and age. Case patients were followed up for 1 year after the index episode of hyperkalemia. Follow-up variables included changes in therapy with ACE inhibitor, maximum potassium for each change, and mortality. RESULTS: Of 1818 patients using ACE inhibitors, 194 (11%) developed hyperkalemia. Results of laboratory studies indicating a serum urea nitrogen level higher than 6.4 mmol/L (18 mg/dL), creatinine level higher than 136 mumol/L (1.5 mg/dL), congestive heart failure, and long-acting ACE inhibitors were independently associated with hyperkalemia; concurrent use of loop or thiazide diuretic agent was associated with reduced risk. After 1 year of follow-up, 15 (10%) of 146 case patients remaining on a regimen of an ACE inhibitor developed severe hyperkalemia (potassium level > 6.0 mmol/L). A serum urea nitrogen level higher than 8.9 mmol/L (25 mg/dL) and age more than 70 years were independently associated with subsequent severe hyperkalemia. CONCLUSIONS: Mild hyperkalemia is common in medical outpatients using ACE inhibitors, especially in those with renal insufficiency or congestive heart failure. However, once hyperkalemia is identified during the use of ACE inhibitors, subsequent severe hyperkalemia is uncommon in patients younger than 70 years with normal renal function.

Understanding racial variation in the use of coronary revascularization procedures: the role of clinical factors.

BACKGROUND: Black patients undergo coronary artery bypass grafting and percutaneous transluminal coronary angioplasty less often than white patients. It is unclear how racial differences in clinical factors contribute to this variation. METHODS: A retrospective cohort study was performed of 666 male patients (326 blacks and 340 whites), admitted to 1 of 6 Veterans Affairs hospitals from October 1, 1989, to September 30, 1995, with acute myocardial infarction or unstable angina who underwent cardiac catheterization. The primary comparison was whether racial differences in percutaneous transluminal coronary angioplasty and coronary artery bypass grafting rates persisted after stratifying by clinical appropriateness of the procedure, measured by the appropriateness scale developed by the RAND Corporation, Santa Monica, Calif. RESULTS: Whites more often than blacks underwent a revascularization procedure (47% vs 28%). There was substantial variation in black-white odds ratios within different appropriateness categories. Blacks were significantly less likely to undergo percutaneous transluminal coronary angioplasty (odds ratio, 0.30; 95% confidence interval, 0.14-0.63 [P<.01]) when the indication was rated "equivocal." Similarly, blacks were less likely to undergo coronary artery bypass grafting (odds ratio, 0.44; 95% confidence interval, 0.23-0.86 [P<.01]) when only coronary artery bypass grafting was indicated as "appropriate and necessary." Differences in comorbidity or use of cigarettes or alcohol did not explain these variations. Using administrative data from the Veterans Health Administration, we found no differences in 1-year (5.2% vs 7.4%) and 5-year (23.3% vs 26.2%) mortality for blacks vs whites. CONCLUSION: Among patients with acute myocardial infarction or unstable angina, variation in clinical factors using RAND appropriateness criteria for procedures explained some, but not all, racial differences in coronary revascularization use.

Changes in Doppler ultrasound sonagrams at varying distances from stenoses.

The effect of different degrees of arterial stenosis on Doppler ultrasound sonagrams recorded from various distances downstream has been investigated in a canine model. It has been found that even mild stenoses give rise to considerable disturbances close to the stenosis, and that more severe stenoses give rise to greater disturbances which propagate further downstream. The distance the disturbances travelled was not related to stroke volume, and it was only for stenoses of 88% area reduction and greater that such disturbances ever propagated beyond one stroke-length. Quantitative assessment of moderate degrees of proximal stenosis using continuous wave Doppler ultrasound will not be reliable unless the distance between the major stenosis and the recording site is known.

Frequency of adverse reactions after influenza vaccination.

PURPOSE: Although concern about side effects constitutes a major deterrent to patient compliance with recommendations for influenza vaccination, there is a paucity of data about the frequency of adverse reactions to newer trivalent vaccines. Our aim was to determine the frequency of adverse reactions to influenza vaccine in older, chronically ill persons, many of whom are at high risk for influenza-related morbidity. PATIENTS AND METHODS: We conducted a telephone survey of 40% of the patients who were vaccinated at a walk-in flu shot clinic. The subjects were randomly assigned to two groups. To determine postvaccine symptom rates, Group I was interviewed seven days after vaccination. Group II was interviewed 21 days after vaccination in order to control for baseline symptom rates. Both groups were queried about fever, disability, and flu-like illness in the week preceding the interview. RESULTS: Of 816 patients selected, 650 (79.6%) completed the interview. The mean age of the subjects was 63, and more than two thirds were at risk for influenza-related morbidity. The frequencies of self-reported fever (5.3% versus 5.1%, p = 0.91) and disability (10.4% versus 9.3%, p = 0.65) were similar in the two groups. However, a significantly higher proportion of Group I subjects reported a flu-like illness compared to the Group II subjects (14.2% versus 8.7%, p = 0.03). Although Group I subjects were more likely to report flu-like illness within two days of vaccination compared to a similar time interval for Group II subjects, there was no corresponding clustering of disability after vaccination. CONCLUSION: We conclude that the overall frequency of symptoms in both groups was low; however, the absolute risk of a flu-like illness was 5.5% higher during the first week following influenza vaccination when compared with the third week after the injection. These symptoms did not result in a decreased ability to perform usual daily activities.

Deciding to restrain medical patients.

To determine when and why patients are placed in mechanical restraints, we surveyed the nurse and physician caring for each of 102 restrained patients from the general medical floors of an acute-care hospital. Ninety-three percent of the questionnaires were completed. Nursing questionnaires indicated that over half of patients were restrained during the evening shift. Nurses initiated the use of restraints in 75% of cases. Fifteen percent of the patients' physicians were unaware that the patient had been restrained. In the majority of cases, the nurse and physician believed that restraint was the best alternative for managing the patient although more physicians (11%) than nurses (2%) thought an alternative intervention would be better (P less than .02). As a group, physicians and nurses restrained patients for similar reasons, most often to prevent falls from bed (69%) or to protect medical devices (36%). However, there was poor agreement between the nurse and physician as to the reason for restraint in an individual patient (kappa statistic range from .02 to .43). These findings suggest that nurse and physician communication regarding restraint is poor. We recommend that acute-care hospitals adopt policies to promote communication between nurses and physicians concerning restraints to ensure that use of this potentially hazardous intervention is used only when necessary.

Preoperative laboratory testing: should any tests be "routine" before surgery?

Routine preoperative testing of all patients before elective surgery is unjustified. The frequency of unanticipated abnormalities or abnormalities shown to change patient management is too low to justify a practice pattern of testing all patients. Furthermore, little evidence exists that test result abnormalities are associated with perioperative morbidity. Table 12 lists a compilation of the findings from this article and recommendations regarding routine testing.

Is aortography in lower limb ischaemia still abused?

A study in 1980 revealed that 38% of aortograms performed in a series had been referred for inappropriate reasons and only 49% had been clearly indicated. Recommendations were made to reduce the number of inappropriate investigations. An audit has been carried out of the aortography referrals made in this unit recently. This has shown that, despite changes in the management of peripheral vascular disease in the intervening years, by following the recommendations made in the previous paper, the number of inappropriate aortograms has been reduced to a minimum. The recommendations are endorsed.

Successful resection of a massive hepatic artery aneurysm.

Hepatic artery (HA) aneurysms are seen infrequently, but many eventually rupture, often with a fatal outcome. With modern diagnostic technology, aneurysms can be identified at an earlier stage, providing the opportunity for intervention. This review outlines the case of a patient with a massive, leaking hepatic artery aneurysm and discusses the aetiology and management of these lesions.

The salvage of occluded Dacron grafts.

The technical details of unblocking occluded Dacron grafts in 8 patients are described. The early results in 4 grafts in 8 patients are described. The early results in 4 unilaterally occluded bifurcation aortic grafts and 1 unilateral iliofemoral graft are encouraging with all 5 grafts patent 8-16 months postoperatively (mean 9 months). We recommend this operation as the procedure of choice in symptomatic patients presenting with a graft occlusion of this type before resorting to the insertion of a new prosthesis, and emphasize the importance of improving the outflow, usually by a profundaplasty. Only 1 out of 5 axillofemoral grafts remains patent at 8 months in spite of vigorous attention to operative detail. In this situation, an alternative procedure is suggested in the long term.

Outpatient internal medicine preoperative evaluation: a randomized clinical trial.

The purpose of this study was to evaluate the effect on resource use of a program outpatient internal medicine preoperative evaluation in a two arm parallel design randomized clinical trial. In a tertiary care teaching Veterans Affairs hospital, 355 patients (179 inpatient arm, 176 outpatient arm)(mean age 65.5 years) were referred for internal medicine preoperative evaluation before elective surgery. Outpatient internist preoperative evaluation was performed 2 to 3 weeks before admission for surgery in the experimental arm with preoperative laboratory and radiology testing performed during the visit. The control arm was admitted for surgery without outpatient evaluation. The main outcome measure was the length of stay. Preoperative length of stay was significantly reduced from 2.9 days in the inpatient arm to 1.6 days in the outpatient arm (P < 0.001, 95% confidence interval of the difference, -0.8 to -1.8 days). Postoperative length of stay in the outpatient arm (3.6 days) was slightly but not significantly longer than the inpatient arm (3.0 days) (95% confidence interval of the increase, -0.6 to 1.8 days). Total length of stay showed no significant difference between the outpatient (5.5 days) and inpatient (6.0 days) arms (95% confidence interval of the difference, -2.0 to 1.1 days). Unnecessary admissions, defined as patients admitted who were admitted but did not undergo surgery, were decreased significantly comparing the inpatient arm (12.3%) to the outpatient arm (5.7%) (95% confidence interval of the difference, 0.5% to 12.7%). Measures of resource use showed no difference between arms including laboratory tests (95% C.I. of the difference, -3.0 to 6.8 tests), imaging tests (95% C.I. of the difference, -0.5 to 0.8 tests) were administered. A significant increase in the use of consultants between the outpatient arm (1.3 consultations) and inpatient arm (0.9 consultations) was discovered (95% C.I. of the difference, 0.2 to 0.6). Patients health status after discharge and satisfaction with care were not different between the two arms of the investigation. A program of outpatient internal medicine preoperative evaluation significantly reduced preoperative length of stay with a lesser effect on total length of stay. Unnecessary admission of patients for elective surgery were reduced by this program.

Common femoral artery Doppler wave-forms: a comparison of three methods of objective analysis with direct pressure measurements.

Doppler maximum frequency wave-forms recorded from the femoral arteries of 50 patients with arterial disease have been submitted to three methods of objective analysis in an attempt to quantify the degree of proximal narrowing. The methods were compared with direct femoral artery pressure measurements at rest and during hyperaemia. There was marked overlap between the results of both pulsatility index and Laplace transform damping when compared with pressure assessment. Principal component analysis, however, produced significantly better agreement than Laplace transform damping (chi 2 = 5.8, P less than 0.02) and in addition was found to be sensitive to the presence or absence of disease in the superficial femoral artery. Principal component analysis appears to be the most powerful method of Doppler wave-form analysis so far described and may have a place in the non-invasive assessment of the aorto-iliac segment.

Testicular teratoma and peripheral neurofibromatosis.

Peripheral neurofibromatosis (Von Recklinghausen's disease) has been previously reported in association with a number of tumours and recently with aqueductal stenosis. We report a case which had both aqueductal stenosis and a testicular teratoma, which has not previously been reported in this condition.

Preoperative screening: value of previous tests.

OBJECTIVE: To determine the frequency of tests done in the year before elective surgery that might substitute for preoperative screening tests and to determine the frequency of test results that change from a normal value to a value likely to alter perioperative management. DESIGN: Retrospective cohort analysis of computerized laboratory data (complete blood count, sodium, potassium, and creatinine levels, prothrombin time, and partial thromboplastin time). SETTING: Urban tertiary care Veterans Affairs Hospital. PATIENTS: Consecutive sample of 1109 patients who had elective surgery in 1988. MEASUREMENTS AND MAIN RESULTS: At admission, 7549 preoperative tests were done, 47% of which duplicated tests performed in the previous year. Of 3096 previous results that were normal as defined by hospital reference range and done closest to the time of but before admission (median interval, 2 months), 13 (0.4%; 95% CI, 0.2% to 0.7%), repeat values were outside a range considered acceptable for surgery. Most of the abnormalities were predictable from the patient's history, and most were not noted in the medical record. Of 461 previous tests that were abnormal, 78 (17%; CI, 13% to 20%) repeat values at admission were outside a range considered acceptable for surgery (P less than 0.001, frequency of clinically important abnormalities of patients with normal previous results with those with abnormal previous results). CONCLUSIONS: Physicians evaluating patients preoperatively could safely substitute the previous test results analyzed in this study for preoperative screening tests if the previous tests are normal and no obvious indication for retesting is present.

Is aortography abused in lower-limb iscaemia?

Request for aortography on 82 patients in one hospital in 1978 were assessed to determine the effect of the investigation on the patient's subsequent management. In 49% of cases the request was fully justified. In the remaining 51% of patients, none of whom had reconstructive surgery, the request was considered either inappropriate (38%) or of marginal value (13%). The reasons for this high porportion of unnecessary aortograms were related to the clinical specialty and the level of experience of the doctor making the request. A simple algorithm which may be helpful when deciding to perform an aortogram is suggested. It is concluded that aortography should be requested only by experienced medical staff and only after a decision has been taken to offer the patient operative treatment.

Digital ischaemia: an unusual presentation of dysbarism.

Dysbaric symptoms following ascent from a scuba dive are due to symptomatic nitrogen or air emboli with clear patterns of associated injury. This case report highlights an unusual presentation of dysbaric injury treated successfully with a prostacyclin analogue.

Pyogenic liver abscess: a study of forty-four cases in two centres.

44 patients with pyogenic liver abscess, 22 each from Leicester, UK, and Göteborg, Sweden, presenting between 1972 and 1980 have been reviewed. 29 patients were diagnosed prior to specific treatment with 3 deaths (10%); 15 patients were first discovered at autopsy resulting in an overall mortality of 41%. The presentation, pathogenesis, and treatment are discussed in detail. It is concluded that the continuing high mortality of this condition largely relates to the difficulty in establishing the diagnosis. Reduced morbidity (and perhaps mortality) might be achieved with wider use of percutaneous methods of drainage.