SPUTUM CULTURE EVALUATES COLONIZAITON IN BRONCHIECTASIS

An old technique—sputum culture—may be an effective way to determine whether a stable bronchiectasis patient has been colonized with potentially pathogenic micro-organisms (PPMs). As an alternative to bronchoscopy, sputum culture could provide an easier way to evaluate patients with risk factors for PPM colonization, such as early diagnosis of bronchiectasis, presence of varicose-cystic bronchiectasis, and a forced expiratory volume in one second (FEV1) less than 80% of predicted.

Angrill et al conducted a two-year prospective study of 77 patients with bronchiectasis. Sputum samples were taken from 71 of these patients using pharyngeal swabs; samples of spontaneous sputum were also collected from 62 patients using a protected specimen brush (PSB). In patients unable to cough, expectoration was induced using nebulized 3% hypertonic saline. Bronchoalveolar lavage (BAL) was then performed in 59 patients, with samples being taken from the most affected lobes.

Of the 77 patients, 38 (49%) were found to have an FEV1 below 80% of predicted; 30 (39%) had normal spirometric results. PSB results and sputum analysis agreed in 30 (75%) of the 40 patients subjected to both tests; 18 of the patients had evidence of PPM colonization on both tests, and 12 had negative results. PSB and BAL results agreed in 48 (80%) of the 60 patients subjected to both tests; 30 patients had positive findings on both tests, and 18 had negative findings. The researchers also found that patients colonized with PPMs had worse lung function scores, overall, than did the patients who had not been colonized.

Angrill J, Agusti C, de Celis R, et al. Bacterial colonisation in patients with bronchiectasis: microbiological pattern and risk factors. Thorax. 2002; 57:15-19.

OXYGEN THERAPY BENEFITS WITH PULMONARY HYPERTENSION

In patients with pulmonary hypertension, 100% oxygen may be a selective pulmonary vasodilator. A recent report indicates that this holds true even for patients who do not meet current national guidelines for long-term oxygen therapy. Furthermore, the efficacy of this treatment does not vary according to primary diagnosis, right ventricular function, or baseline oxygenation.

Roberts et al evaluated 23 adult patients who suffered from pulmonary arterial hypertension without left-heart failure. They treated these patients first with air and then with 100% oxygen.

The researchers found that oxygen administration increased arterial oxygen saturation from an average of 91% to an average of 99%, and it decreased mean pulmonary artery pressure from 56 to 53 mm Hg. Cardiac index increased from 2.1 to 2.5 L/min/m2, while mean pulmonary vascular resistance decreased from 14.1 to 10.6 Wood units. Furthermore, pulmonary vascular resistance (PVR) was favorably reduced in comparison with systemic vascular resistance, with the ratio dropping from 0.53 to 0.48. The magnitude of PVR response, however, was associated with decreasing patient age.

The researchers believe that raising arterial oxygen tension beyond the minimum goal of 60 mm Hg with supplemental oxygen could improve PVR and cardiac index, at least in the short term. They speculated that this could be due to release of hypoxic pulmonary vasoconstriction, but that other undefined mechanisms may also play a role.

Roberts DH, Lepore JJ, Maroo A, et al. Oxygen therapy improves cardiac index and pulmonary vascular resistance in patients with pulmonary hypertension. Chest. 2001;120:1547-1555.

RESEARCH SHEDS LIGHT ON UNEXPLAINED INFECTIOUS DISEASES

How often do unexplained deaths result from infectious causes? How many critically ill patients are infected by unrecognized rare or new organisms? To help answer these questions, Hajjeh et al used data gathered from four areas of the United States between May 1995 and December 1998 to define the incidence, epidemiologic features, and possible causes of such illnesses and deaths

The four areas of surveillance included 7.7 million people. The researchers defined a UNEX (for unexplained) case as illness in a patient who was previously healthy and who either died or was hospitalized as a result. The illness must have exhibited hallmarks of infection but could not be specifically diagnosed. Of the 525 possible UNEX cases initially identified, 137 met these criteria. The cases were identified a median of six days after hospital admission. In 41 cases (30%), the patients died.

The initial presentation suggested a neurologic syndrome in 39 cases (29%), a respiratory disorder in 36 cases (26%), and a cardiac condition in 28 cases (20%). The death rate was highest when cardiac involvement was suspected (46%) and lowest when a neurologic syndrome was suspected (18%). A specific diagnosis of an infectious disease could be made in 34 cases (25%).

Based on these results, the researchers estimate that 920 UNEX cases occur in this country each year.

Hajjeh R, Relman D, Cieslak P, et al. Surveillance for unexplained deaths and critical illness due to possibly infectious causes, United States, 1995-1998. Emerg Infect Dis. 2002;8:145-153.

CARETAKER STRESS LINKED TO INCREASED INFANT WHEEZE

Psychosocial stress affecting caretaker behavior may translate into similar stress for children. According to a recent report, the complex immunologic alterations that result may culminate in wheezing or other physiological signs and symptoms.

Wright et al evaluated 496 infants from families with histories of asthma or allergy. They were entered into the study within 48 hours of delivery, between September 1994 and July 1996. When each child was age 2 or 3 months, data were collected on home exposures to smoke or indoor allergens, sociodemographics, and caregiver stress. Six bimonthly telephone questionnaires followed, in which changes in caretaker stress, maternal smoking, and infant feeding were assessed and the incidence of respiratory illness in children was measured.

The researchers found that increased caregiver stress was associated with an increased risk for child wheezing when both were assessed during the same period. In prospective analysis, a similar trend was reported: Caregiver stress during the last month correlated with increased wheezing in the child during the two months that followed. No evidence was found that a child’s wheezing was the cause of a caretaker’s stress.

Furthermore, the link between caretaker stress and child wheezing was not explained by the child’s exposure to allergens, maternal smoking, lower respiratory tract infection, or breast-feeding. This suggested a more direct connection between airway inflammation and the immune system, the researchers said.

Wright R, Cohen S, Carey V, et al. Parental stress as a predictor of wheezing in infancy. Am J Resp Crit Care Med. 2002;165:358-365.