Journal Club
JOURNAL CLUB
COMMENTARIES BY MICHAEL G. BURKE, MD
Herniation and diagnostic LP in meningitis
A recent case report describes a 12-year-old thought to have bacterial meningitis who suffered a fatal cerebral hernia following a diagnostic lumbar puncture (LP). The boy came to a community hospital emergency department after having a single generalized tonic-clonic seizure, following two days of fever, headache, vomiting, and increasing somnolence. Examination revealed signs of meningitis. An unenhanced computed tomography (CT) scan of the brain did not indicate elevated intracranial pressure, so a diagnostic LP was performed. The opening pressure was not measured. Fifteen minutes after the LP, the patient became hypotensive and was promptly intubated, stabilized with mechanical ventilation, and given mannitol. He was transferred to the pediatric intensive care unit (PICU), deeply comatose. Despite vigorous resuscitation and therapy for presumed herniation, he died 12 hours after admission to the PICU
According to investigators, this is the second documented report of meningitis associated with herniation and death in a child with a normal head CT scan. The authors discourage relying entirely on CT scan for assessing intracranial pressure before LP. Instead they recommend considering progressive loss of consciousness, especially after a seizure, and other signs of increased ICP. Opening pressure during LP may allow early identification of markedly elevated ICP, allowing treatment to prevent herniation. Investigators recommend avoiding LP in children with suspected meningitis in whom there is clinical evidence of raised ICP or early herniation--even in the face of a normal CT scan (Shetty AK et al: Pediatrics 1999;103[6]:1284).
Commentary: The message here is that a normal CT scan in a child with possible meningitis is not completely reassuring, especially if findings in the physical examination or hints in the early clinical course suggest increased ICP. Any of these clues would justify delaying the LP until after initial therapy and stabilization. The next question is, does every child with suspected meningitis require a CT prior to LP? Dr. Robert Haslam wrote that CT is not routinely indicated in evaluation for meningitis (Pediatrics 1991;119:157). In our emergency room, we have moved away from that recommendation and do CT before nearly all LPs. Are there cases when this still is not required?
How common are GABHS carriers?
Contrary to other studies, a new investigation of Group A b-hemolytic streptococcus (GABHS)carriage found that only a small percentage of children seen in private pediatric practices who are well or who have apparent viral upper respiratory tract infections with sore throat are GABHS carriers. The study was conducted during a nine-month period at a private-practice pediatric group near Rochester, NY. Investigators cultured samples from children who were asymptomatic and well; children with either presumed or documented viral sore throats; and children who had completed a full antibiotic treatment course for acute GABHS throat infections. Of the 227 well children, 2.5% were GABHS carriers. Of the 296 children with sore throat believed to be viral, incidence was 4.4%, and among the 87 children with sore throat and documented viral illness it was 6.9%. As to the children treated for acute GABHS for 10 days, penicillin resulted in a higher GABHS carriage rate--11.3% of 718 children--than treatment with either cephalosporins (4.3% of 508) or macrolides (7.1% of 140) (Pichichero ME et al: Arch Pediatr Adolesc Med 1999;153:624).
Commentary: These rates are significantly lower than the 10% strep carrier rates that we have all accepted. In their discussion, the authors explain how differences in study design and culture technique may explain these differences. They make a strong argument that these new data reflect what you see in your practice.
Teen drinking and driving
As part of the Monitoring the Future project on drug and alcohol use, investigators estimated how often high school seniors drive after drinking or ride with a driver who has been drinking. They based their estimates on representative samples of about 17,000 12th graders in 135 schools selected each year to complete a confidential questionnaire. Though the project has been underway since 1975, questions about driving and drinking first were included in 1984.
Rates of adolescent driving after drinking and riding with a driver who had been drinking declined significantly from the mid-1980s to the early or mid-1990s, the research shows, but the declines have not continued in recent years. Prevalence of driving after drinking was 31.2% in 1984; it declined to 15% by 1995, then showed a nonsignificant increase to 18.3% by 1997. The prevalence of being a passenger in a car driven by a person who has been drinking declined from 44.2% in 1984 to 23.1% in 1995, followed by an nonsignificant increase to 26.1% in 1997. High school seniors who were male, white, and lived in the West or Northeast and in rural areas were more likely than other seniors to drive after drinking or to drive with someone who had been drinking. Alcohol-related driving or riding was associated with truancy, going out in the evening, and illicit drug use. Seniors with the highest grade-point average and strongest religious commitment had the lowest rates of alcohol-related driving or riding. The more miles the teen had driven in a week the greater the likelihood of driving after drinking (O'Malley PA et al: Am J Public Health 1999;89:678).
Commentary: The decline in drinking and driving was associated with an increase in the number of seniors who thought their friends would disapprove this combination. Although the study offers no proof of cause and effect, this may be an example of how peer pressure can benefit the health of adolescents.
SIDS message needs reinforcement
Parents often change the sleep positions of their infants in the first six months of life, even when the parents have received "back to sleep" information, according to a recent study from the Children's National Medical Center Pediatric Research Network. This group of practice-based pediatricians began following 348 infants soon after birth, when they instructed parents to avoid placing their babies on their stomachs to sleep and gave them an American Academy of Pediatrics "Back to Sleep" brochure. Parents were telephoned at one week and then monthly to remind them to record their infants' sleep position in a study log but were not given any further advice on sleep position as part of the study. When each infant was 6 months old, investigators saw the parents' sleep log data for the first time and questioned parents about why they chose their baby's initial sleep position and reasons for making any changes.
At 1 week of age, 12.2% of infants were put on their stomachs to sleep; this number increased to 32.9% at 6 months. Supine sleeping also increased, from 28.3% to 48.2%, while side sleeping decreased from 57.1% to 14.3%. Most parents who changed their infants' sleep position did so because they thought their baby slept better or was more comfortable in a different position. Others had no reason , and a few cited a specific medical indication, media exposure, advice from a health-care provider or from a relative or friend, or previous experience. Certain factors were associated with prone sleeping: in the baby, male sex, having siblings, and black race, and in the mother, lower education level and single marital status.
Only one third of pediatricians discussed sleep position beyond the newborn period, and few distributed the "Back to Sleep" brochure in their offices, except to those enrolled in the study. Investigators concluded that pediatricians need to consistently reinforce the "Back to Sleep" message when infants are 2 to 4 months old--the time they are most likely to be switched to their stomachs and the highest risk period for sudden infant death syndrome (Ottolini MC et al: Arch Pediatr Adolesc Med 1999;153:512).
Commentary: All of the parents in this study received initial advice and literature about sleep position. It would be interesting to know how many of them remembered that advice but put their babies on their stomachs, anyway.
Many children exposed to firearms at home
Investigators surveyed more than 5,000 households to estimate the national prevalence of firearms and compare storage practices in homes with and without children. Using a random-digit dialing phone survey of English- and Spanish-speaking adults throughout the country, they determined that one third of households had at least one firearm in the home or a vehicle.
Of the 1,598 households that had one or more firearms and could categorize their storage practices, 21.5% kept at least one gun loaded and unlocked in the home, and 30% stored all firearms unloaded and locked. The remaining 48.5% of households followed "intermediate" storage practices. Households with children were much more likely than those without children to store all firearms unloaded and locked--29.8% compared with 11.1%. Southern households were more likely (17.6%) to store at least one firearm loaded and unlocked than households in the rest of the country (7.0%) (Stennies G et al: Arch Pediatr Adolesc Med 1999;153:586).
Commentary: The authors estimate that 1.6 million US homes have both children and an unlocked, loaded gun. Ask about this issue during health maintenance visits. You may be surprised at the answers you hear.
Also of note
Pertussis IGIV for treating severe pertussis in infancy. Investigators studied the safety of using intravenous pertussis immunoglobulin (P-IGIV) in infants with confirmed pertussis and got a preliminary look at the treatment's clinical effects. The study subjects, 26 children younger than 2 years with laboratory-confirmed pertussis, were divided into three treatment groups. Those who received the largest P-IGIV doses--1,500 mg/kg--showed a four-fold rise in peak geometric mean titers of pertussis toxin IgG antibodies. Children in the 750 and 250 mg/kg treatment groups had three-fold and two-fold rises, respectively, in these antibodies. No adverse effects were associated with P-IGIV, except that one child had transient hypotension, which responded to a decrease in the infusion rate. In all three treatment groups, paroxysmal coughing, desaturations, and bradycardic episodes rapidly improved within 72 hours of infusion. The authors believe that data from this study can be the basis for a randomized, controlled efficacy trial (Bruss JB et al: Pediatr Infect Dis J 1999;18:505).
Effective approach to diagnosing iron deficiency. Investigators evaluated a relatively new parameter for diagnosing iron deficiency and iron deficiency anemia in children: reticulocyte hemoglobin content (CHr). They collected blood samples from 210 children with a mean age of 2.9 years; 43 of the children were classified as iron deficient and 24 of those 43 had iron-deficiency anemia. In addition to being checked for CHr levels, blood samples were analyzed for traditional hematologic and biochemical indicators of simple iron deficiency, including hemoglobin, transferrin, transferrin saturation, and ferritin. The children with iron deficiency and iron-deficiency anemia had markedly different hemoglobin levels than children who were healthy and their CHr was significantly decreased. Plasma ferritin, which traditionally is used in adults to estimate iron stores, was not substantially different in these two groups compared with healthy children, however. Investigators concluded that CHr is a strong predictor of iron deficiency and iron-deficiency anemia in children (Brugnara C et al: JAMA 1999;281:2225).
DR. BURKE, Section Editor for Journal Club, is Chairman of the Department of Pediatrics at Saint Agnes Hospital, Baltimore.
Marian Freedman. Journal Club. Contemporary Pediatrics 1999;8:141.
