VASCULAR RINGS MAY MIMIC ASTHMA

Patients who appear to have developed asthma in adulthood may actually have congenital vascular rings compressing the trachea or esophagus, researchers reported in a recent case review. Particularly at risk for this condition are people with an abnormally flattened expiratory loop who have a reduced peak expiratory flow (PEF) rate.

Parker et al diagnosed four cases of symptomatic vascular rings in adults who had been unsuccessfully treated for asthma. These anomalies are caused by abnormal development of the primitive aortic arch. For example, in two of the patients, the vascular ring was formed by a right aortic arch with a persistent ligamentum arteriosum.

"Spirometric values were deceptively normal, except for reduced PEF," the researchers found. The key to the diagnosis was that all of the patients had an abnormally truncated expiratory flow loop. In each case, chest films showed a right aortic arch, and computed tomography or magnetic resonance imaging scans confirmed the diagnosis of a vascular ring.

While congenital vascular rings are well recognized in infants and children, this condition is not often considered as an alternative diagnosis to asthma in adults because adults are usually evaluated by physicians who are less familiar with congenital abnormalities. "Failure to consider this possibility may result in a misdiagnosis of asthma, with the use of ineffective and expensive medications," the researchers concluded.

Parker JM, Cary-Freitas B, Berg BW. Symptomatic vascular rings in adulthood: an uncommon mimic of asthma. J Asthma. 2000;37:275-280.

CATHETER-ASSOCIATED URINARY TRACT INFECTIONS ARE USUALLY ASYMPTOMATIC

Most cases of catheter-associated urinary tract infection (UTIs) are asymptomatic, according to data from a prospective trial. Furthermore, those symptoms that are related to catheter-associated UTIs are of little value in the diagnosis of these infections.

Tambyah and Maki evaluated 1,497 newly catheterized patients for signs and symptoms commonly associated with UTIs (fever, dysuria, urgency, or flank pain). For all patients, qualitative urine cultures and urine leukocyte counts were also performed.

The researchers identified 235 UTIs in 224 patients, 92.3% of whom were asymptomatic. Interestingly, the patients' physicians had diagnosed only 52% of the 235 infections. Only one of the catheter-associated UTIs was unequivocally associated with a secondary bloodstream infection.

Because many of the patients in the original cohort had another active infection unrelated to the urinary tract, the researchers also examined a subset of 1,034 patients with either no infection (n = 945) or catheter-associated UTIs (n = 89). These two groups were similar in regard to UTI signs and symptoms as well as mean peripheral leukocyte counts. The only significant difference between the two groups was a higher mean urine white blood cell count in the catheter-associated UTI group.

According to the researchers, asymptomatic UTIs "comprise a huge silent reservoir of antibiotic-resistant bacteria and yeasts." Thus, they recommend improved catheter care to prevent such infections.

Tambyah PA, Maki DG. Catheter-associated urinary tract infection is rarely symptomatic: a prospective study of 1,497 catheterized patients. Arch Intern Med. 2000;160:678-682.

RACIAL DIFFERENCES IN END-OF-LIFE DECISIONS

Elderly blacks are less likely than elderly whites to discuss or document their preferences for end-of-life care and are more likely to choose aggressive measures to prolong life, according to recent findings.

Hopp and Duffy studied survey responses from relatives of 540 people who died between the first (1993) and second (1995) waves of the Asset and Health Dynamics Among the Oldest Old study. The survey consisted of questions about advanced care planning and end-of-life decisions that were made about the deceased, all of whom were age 70 years or older in 1993.

Blacks were significantly less likely than whites to discuss treatment preferences before death, to complete a living will, or to designate a durable power of attorney for health care (Table 1). However, blacks were more likely than whites to choose aggressive forms of end-of-life care.

"The lower rate of advance care planning among blacks may be the result of previous experience with being denied medical care and distrust of the medical system," the researchers noted. Also, they added, blacks may believe that advance directives will limit the care they will receive rather than serve as a way of controlling care decisions that affect them.

Hopp FP, Duffy SA. Racial variations in end-of-life care. J Am Geriatr Soc. 2000;48:658-663.

COCAINE USE MAY INCREASE ASTHMA MORBIDITY

A relatively high prevalence of cocaine use was found among patients with asthma exacerbations in a recent study. The actual prevalence may be much higher, Rome et al noted, because 29% of the total group refused to submit urine samples.

Of 163 adults who presented to an inner-city emergency department with acute asthma exacerbations, 37 patients refused to participate; an additional 10 were excluded because of language barriers, psychiatric illness, or other logistical problems. Of the 116 remaining patients, complete urine samples were available for 103.

In 13 patients, urine samples were positive for cocaine; in six, they were positive for opiates. Patients with evidence of cocaine use had a greater frequency of hospital admissions than did those with negative results (38% vs 20%), but the difference was not statistically significant. Among those who were admitted to the hospital, cocaine-positive patients had a significantly longer length of stay than did cocaine-negative patients (5 vs 2.5 days). Furthermore, two of three patients who required intubation were cocaine-positive.

These findings suggest that cocaine use may be associated with more severe asthma exacerbations. Rome et al admitted that they were unable to control for potentially confounding factors, such as access to health care, tobacco smoking, and appropriate use of medications. The researchers also explained that it would have been helpful to compare the prevalence of cocaine use in this cohort with that among nonasthmatic control subjects.

Rome LA, Lippmann ML, Dalsey WC, et al. Prevalence of cocaine use and its impact on asthma exacerbation in an urban population. Chest. 2000;117:1324-1329.

COPD PATIENTS BENEFIT FROM ANTIBIOTIC THERAPY

Patients with acute exacerbations of chronic obstructive pulmonary disease (COPD) are less likely to experience a relapse if they are given certain antibiotics, according to a recent analysis. However, not all antibiotics are beneficial. In fact, patients given amoxicillin had the highest relapse rate--even higher than that among untreated patients.

Adams et al compared the outcomes of 173 people who had a total of 362 office visits for acute exacerbations of COPD. Each visit was analyzed separately.

Antibiotics were most likely to be administered when the exacerbation was severe; in fact, almost all (95%) of the 154 severe exacerbations were treated with antibiotics, while less than half (40%) of 88 mild cases were so treated. Despite the association between antibiotic use and disease severity, the 14-day relapse rate was significantly higher for untreated exacerbations than for treated exacerbations (32% vs 19%).

Interestingly, the highest relapse rate was found among patients treated with amoxicillin (54%). Adams et al suggested that this increased incidence may be related to the relatively high rate of resistance to amoxicillin at the study hospital. All of the other antibiotics studied decreased the relapse rate; however, patients treated with macrolides or ciprofloxacin were somewhat more likely to suffer relapses than were patients given cephalosporins, trimethoprim-sulfamethoxazole, or amoxicillin-clavulanate.

Adams SG, Melo J, Luther M, Anzueto A. Antibiotics are associated with lower relapse rates in outpatients with acute exacerbations of COPD. Chest. 2000;117:1345-1352.

IS DETECTION OF SMALL LUNG CANCER TUMORS USEFUL?

Detection of small lung cancer tumors may have no impact on survival, according to a study by Patz et al. The researchers believe that by the time a lesion has grown to 5 mm (close to the detectable range of a computed tomography [CT] scan), the cancer is already late in the biology of the disease.

The study involved 510 patients with surgically resected pathological stage IA non-small-cell lung cancer. Of this group, 38% had squamous cell carcinoma, 46% had adenocarcinoma, 9% had bronchoalveolar cell carcinoma, and 7% had large cell carcinoma.

As shown in Table 2, tumor size did not influence survival. Even when the authors divided tumor size into deciles, the groups had similar survival rates. Thus, it appears that the size of lung cancer nodules does not necessarily correspond to the biological behavior of the disease.

In an accompanying editorial, William C. Black, MD, noted that the findings "force us to think hard about screening with CT and remind us that survival statistics can be very misleading." He also believes that "we should not rush headlong into screening before its effectiveness has been demonstrated by randomized clinical trials."

Patz EF Jr, Rossi S, Harpole DH Jr, et al. Correlation of tumor size and survival in patients with stage IA non--small cell lung cancer. Chest. 2000;117:1568-1571.
Black WC. Unexpected observations on tumor size and survival in stage IA non--small cell lung cancer. [editorial] Chest. 2000; 117:1532-1534.

MDI VERSUS NEBULIZER IN THE DELIVERY OF BRONCHODILATORS

A metered-dose inhaler (MDI) with a metal spacer was as effective as aerosol nebulization in the delivery of albuterol (salbutamol) to small children in a study by Mandelberg et al.

Forty-two children (age 10 months to 4 years) who presented to an emergency department with acute wheeze were randomized to 2.5 mg nebulized albuterol or four puffs (400 mg) of inhaled albuterol delivered through an MDI with a metal, nonelectrostatic spacer and a face mask. All patients received a total of three treatments given at 20-minute intervals.

The overall percent fall in the respiratory rate from baseline was similar in the MDI and nebulizer groups (17.9% and 18.6%, respectively). In fact, the groups showed similar rates of decline at each 20-minute time interval. In addition, the percent fall in clinical scores did not differ at any time point. Overall, these scores fell 23.2% and 24.7%, respectively.

Furthermore, the method of delivery did not affect the hospitalization rate, the pulse rate, or the saturation of oxyhemoglobin while the patient was breathing room air. No adverse effects were reported in either group. The researchers reported similar findings in a study of adults treated for severe airflow limitation.

"Wet nebulization is more expensive and time-consuming for patients and practitioners, with little or no added benefit," noted Charles W. Callahan, DO, in an accompanying editorial. He added that clinical and physiologic evidence supports the use of MDI therapy in the place of nebulization.

Mandelberg A, Tsehori S, Houri S, et al. Is nebulized aerosol treatment necessary in the pediatric emergency department? Chest. 2000;117:1309-1313.

SHOULD CANCER PATIENTS BE ADMITTED TO THE ICU?

Reluctance to admit cancer patients to the intensive care unit (ICU) is not justified, according to data from a retrospective cohort study. While the findings suggest that ICU admission is associated with a poor prognosis in these patients, the rate of ICU mortality in cancer patients is comparable with that in severely ill patients without cancer.

Staudinger et al followed 414 cancer patients admitted to an ICU as well as two control groups: 2,772 cancer patients not admitted to the ICU and 1,362 patients admitted to the ICU with noncancer diagnoses. The subjects were followed for one to 5.5 years after ICU admission.

The cancer patients treated in the ICU had the highest one-year crude mortality rate (77% vs 44% for cancer patients not admitted and 37% for noncancer patients). However, according to the authors, the 77% mortality rate is similar to or lower than that found in studies involving severely ill patients with pneumonia, respiratory distress syndrome, sepsis, or renal or multiple organ failure, as well as patients who require cardiopulmonary resuscitation.

Age, neutropenia, and underlying disease were not significant predictors of outcome. APACHE III scores correlated positively with mortality but were not accurate predictors of individual outcome. "Scoring systems alone should not be used to make decisions about prolongation of resource-consuming treatment; rather, they serve to define patients at high risk who should be treated intensively and early," Staudinger et al believe.

Staudinger T, Stoiser B, MŸllner M, et al. Outcome and prognostic factors in critically ill cancer patients admitted to the intensive care unit. Crit Care Med. 2000;28:1322-1328.