TWO IS BETTER THAN ONE IN APNEA DETECTION

Because apnea-hypopnea and microarousal indexes vary from night to night, a second polysomnographic recording may be required to detect apnea in patients with negative findings on first testing.

A total of 243 patients suspected of having sleep apnea underwent polysomnography on two consecutive nights. A classic first-night effect was found; patients had a shorter sleep period time and total sleep time, less sleep efficiency, longer sleep-onset latency, more wake time after sleep onset, a higher awakening index, less rapid eye movement (REM) sleep time, and a longer REM sleep latency on night 1 than on night 2. These differences were statistically significant. The nonrespiratory microarousal index was also markedly higher on night 1 than on night 2.

In terms of sleep respiratory events, the polysomnographic recording on night 1 showed significantly less evidence of obstructive apnea, total apnea, hypopnea, and combined apnea-hypopnea than did the recording on night 2 (Table 1). The number of desaturations of 3% or more was lower on night 1, while the index of desaturations of 3% or more was lower on night 2.

Sixty-two patients had higher apnea-hypopnea indexes on night 2; only 32 had higher numbers on night 1. "This finding underscores the larger proportion of subjects having more severe respiratory events on night 2," Le Bon et al reported. The study researchers also found that severe apnea-hypopnea indexes occurred more often on night 2--when sleep quality was better.

Le Bon O, Hoffmann G, Tecco J, et al. Mild to moderate sleep respiratory events: one negative night may not be enough. Chest. 2000;118:353-359.

INTRANASAL MIDAZOLAM FOR FEBRILE SEIZURES

Intranasal midazolam is a safe and effective treatment for febrile seizures in children and may be used in general practice as well as by parents at home, according to the results of a recent study. While time from administration to seizure control was faster with intravenous diazepam than with intranasal midazolam, the latter treatment (which is administered more quickly) showed a faster time to cessation of seizures.

Lahat et al compared the effects of 0.2 mg/kg intranasal midazolam and 0.3 mg/kg intravenous diazepam in the treatment of 52 prolonged febrile seizures (ie, those lasting 10 minutes or more) in 44 children age 6 months to 5 years. The patient groups had similar clinical characteristics.

The proportion of seizures that responded to treatment was similar in both groups (88% with midazolam and 92% with diazepam). Time to cessation of seizure after receipt of the drug was significantly faster among children who received diazepam than among those who were given midazolam (2.5 minutes vs 3.1 minutes, respectively).

On the other hand, time to cessation of seizure after arrival at the hospital was significantly faster among those patients who received midazolam than among those who were given diazepam (6.1 minutes vs 8.0 minutes, respectively). "This is because midazolam was administered earlier and the administration of diazepam requires an intravenous line," explained Gideon Koren, MD, in an accompanying editorial.

None of the children developed side effects. "In conclusion, intranasal midazolam could be provided not only in medical centres but, with appropriate instruction, by the parents of children with febrile seizures at home," Lahat et al noted.

Koren G. Intranasal midazolam for febrile seizures. A step forward in treating a common and distressing condition. BMJ. 2000;321:64-65.
Lahat E, Goldman M, Barr J, et al. Comparison of intranasal midazolam with intravenous diazepam for treating febrile seizures in children: prospective randomised study. BMJ. 2000;321:83-86.

DO SIBLINGS, DAY CARE REDUCE RISK OF ASTHMA?

Children who attend day care in the first six months of life or who have older siblings may be at reduced risk for developing asthma and frequent wheezing later in childhood, Ball et al have found. The researchers hypothesized that greater acquisition of respiratory infections during infancy may in some way protect against asthma and wheezing later in life.

The researchers followed a total of 1,035 children from birth to age 13 years. The subjects' parents completed questionnaires concerning their children's respiratory status at age 6, 8, 11, and 13 years. Children who had been diagnosed with asthma and who had experienced an asthma exacerbation in the previous year were categorized as having asthma. Frequent wheeze was defined as the occurrence of four or more wheezing episodes in the previous year.

Children living with one or more siblings had a significantly lower risk of developing asthma than did those with no siblings. In fact, each additional older sibling equated to a 20% reduction in the adjusted relative risk of asthma. Children who attended day care in the first six months of life had a significantly lower risk of asthma than did those who did not attend day care (adjusted relative risk, 0.4).

The presence of siblings and attendance at day care during the first six months of life were associated with a 40% increase in the risk of frequent wheezing at age 2 years, according to Ball et al. However, these two factors were associated with a 20% decrease in the risk of frequent wheezing at age 6 years, a 40% decrease at age 8 years, a 60% decrease at age 11 years, and a 70% decrease at age 13 years. Similar relationships were found when each variable was examined separately.

Ball TM, Castro-Rodriguez JA, Griffith KA, et al. Siblings, day-care attendance, and the risk of asthma and wheezing during childhood. N Engl J Med. 2000;343:538-543.

STEROID WITHDRAWAL IN COPD PATIENTS

Patients with chronic obstructive pulmonary disease (COPD) who stop taking oral corticosteroids on a daily basis do not appear to experience an increase in COPD exacerbations or a worsening of dyspnea, subjective health ratings, or spirometric values, according to a recent placebo-controlled trial. The findings showed that discontinuation of daily corticosteroids reduced the patients' total exposure to systemic corticosteroids and their body weight.

Thirty-eight male COPD patients who had been taking oral prednisone at a dosage of 5 mg/d or higher for at least six months were randomized to continue with their usual prednisone dosage or to taper off prednisone at a rate of 5 mg/wk. Patients in both groups were given prednisone as needed for COPD exacerbations. The two groups were similar in regard to age, spirometric values, bronchodilator response, duration and dose of prior oral corticosteroid treatment, and use of inhaled corticosteroids.

During six months of follow-up, the groups had a similar number of COPD exacerbations per patient (2.5 with continuous treatment and 2.7 following treatment cessation). Measurements of dyspnea, quality of life, forced expiratory volume in one second, and forced vital capacity were similar in the two groups and did not change significantly from baseline levels.

Patients who continued daily treatment gained a mean of 0.5 kg, while patients who took prednisone only during exacerbations lost a mean of 4.8 kg; this difference was statistically significant. In addition, the mean daily systemic corticosteroid dosage was significantly higher in the former group than in the latter group (10.7 mg vs 6.3 mg).

Rice KL, Rubins JB, Lebahn F, et al. Withdrawal of chronic systemic corticosteroids in patients with COPD. A randomized trial. Am J Respir Crit Care Med. 2000;162:174-178.

AIRWAY STRUCTURE IN FATAL ASTHMA

Smooth muscle contraction and production of an inflammatory mucus exudate play a role in fatal asthma attacks, new findings suggest. The data also support the hypothesis that the duration of asthma is associated with progressive airway wall remodeling, reported Bai et al.

The researchers examined lung tissue from 27 randomly selected cases of fatal asthma. Fourteen subjects were age 17 to 23 years at the time of death, and 13 were age 40 to 49 years. Airway dimensions from the patients with fatal attacks were compared with those from 11 controls (five young and six older subjects who died in motor vehicle accidents).

The average wall area was similar among young and older controls. Among those with fatal asthma, however, it was about three times higher in the older than in the young patients. This difference was mainly caused by a greater adventitial area in the older patients.

Regardless of age, patients with fatal asthma had greater connective tissue matrix around smooth muscle cells than did control patients. However, smooth muscle area was only twofold larger in the young asthma patients than in the young controls--but fourfold larger in the older asthma patients than in the older controls.

Both age and asthma influenced the extent of airway narrowing. Among those with fatal asthma, airway narrowing was more marked in the older than in the young patients, but both subgroups had increased airway narrowing compared with age-matched controls.

In addition, both subgroups of asthma patients also had significantly greater intraluminal obstruction (from luminal mucus-debris) and subepithelial collagen thickness than did control subjects, but this effect did not vary by age. In fact, the findings suggest that "it is very uncommon to die [of asthma] without substantial luminal obstruction," the researchers concluded.

Overall, wall dimensions were not significantly different between young patients with fatal asthma and age-matched controls but were significantly increased in older asthma patients versus older controls, the researchers reported. "These results suggest that with increased duration of asthma there is ongoing remodeling with an increase in airway tissue" and that factors other than airway dimensions contribute to the pathogenesis of fatal asthma in young patients, according to the study authors.

Bai TR, Cooper J, Koelmeyer T, et al. The effect of age and duration of disease on airway structure in fatal asthma. Am J Respir Crit Care Med. 2000;162:663-669.

TB PREVENTION IN HIV PATIENTS

Many tuberculosis (TB) programs miss opportunities for preventing active TB among people infected with the human immunodeficiency virus (HIV) who are in close contact with patients with active TB, new findings suggest.

Researchers examined common practices at public health clinics in 11 major urban areas and found HIV status was unknown for 87% of 6,225 people who were close contacts of infectious TB patients. One quarter of the 109 contacts with known HIV infection were not screened completely for TB. Furthermore, of 95 known HIV-infected contacts without active TB, only a third started--and a sixth completed--preventive treatment for TB infection.

These findings indicate a need for increased awareness among health care providers and HIV-infected people of the importance of adequate TB screening and benefits of treatment for latent TB infection, according to the authors. The study also points out the need for TB programs to make HIV counseling and testing services available to all close contacts of TB patients, and to ensure that preventive treatment is started and completed.

Missed opportunities for prevention of tuberculosis among persons with HIV infection--selected locations, United States, 1996-1997. MMWR Morb Mortal Wkly Rep. 2000;49:685-687.

MONOXIDINE EFFECTIVE FOR HYPERTENSION AND PULMONARY DISEASE

The new antihypertensive agent moxonidine has been found to be as effective as ramipril in the treatment of patients with hypertension and obstructive pulmonary disease, according to research by Feuring et al. However, moxonidine does not appear to have any effect on lung function.

The researchers randomized 104 adults to eight weeks of treatment with either moxonidine (0.2 or 0.4 mg/d) or the angiotensin-converting enzyme inhibitor ramipril (2.5 or 5 mg/d). All of the patients had essential hypertension in addition to bronchitis or moderate chronic airway obstruction.

Both groups experienced small changes in arterial oxygen tension. Forced expiratory volume in one second remained constant in the moxonidine group but decreased slightly in the ramipril group. The drugs achieved a similar reduction in systolic and diastolic blood pressure. Treatment with moxonidine did not alter any other indexes of lung function or blood gases.

Furthermore, a similar proportion of patients in each group experienced drug-related adverse effects (13.5% with moxonidine and 11.5% with ramipril). Both drugs were generally well tolerated.

"The results of this study suggest that moxonidine may be recommended as an effective antihypertensive drug in the long-term therapy of patients with arterial hypertension and concomitant pulmonary disease," the researchers concluded.

Feuring M, Cassel W, Thun B, et al. Moxonidine and ramipril in patients with hypertension and obstructive pulmonary disease. Clin Drug Invest. 2000;20:19-24.