CAUSES OF RECURRENT PEDIATRIC PNEUMONIA

Most children with recurrent pneumonia have an underlying illness--often, oropharyngeal incoordination leading to aspiration, Owayed et al found in a recent retrospective review.

The researchers evaluated medical records from 238 children younger than age 18 years. Each child had had at least two pneumonia episodes within one year or at least three episodes in his or her lifetime.

Almost all of the patients (92%) had an underlying illness, including aspiration syndrome secondary to oropharyngeal muscle incoordination (48%), immune disorders (10%), congenital cardiac defects (9%), bronchial asthma (8%), pulmonary anomalies (8%), gastroesophageal reflux (5%), and sickle cell anemia (4%). Cerebral palsy accounted for almost half of the cases of aspiration disorders.

In 81% of cases, the underlying illness had been diagnosed before the first case of pneumonia occurred. Aspiration disorders, immune disorders, and congenital heart disease tended to be diagnosed before the first case of pneumonia, whereas asthma, respiratory tract anomalies, and gastroesophageal reflux were often not recognized until later. Of these, asthma was the most common undiagnosed illness.

Owayed et al noted that the following can be considered clinical clues to diagnosis in children with pneumonia:

• Immune disorders: Recurrent infections at other locations and failure to thrive.
• Underlying pulmonary pathology: Recurrences involving the same location.
• Gastroesophageal reflux: The association of respiratory symptoms with feeding.
• Asthma: Recurrent wheezing.

Owayed AF, Campbell DM, Wang EEL. Underlying causes of recurrent pneumonia in children. Arch Pediatr Adolesc Med. 2000;154:190-194.

IDIOPATHIC ENVIRONMENTAL INTOLERANCE AND PANIC

Patients with idiopathic environmental intolerance (IEI)--formerly known as multiple chemical sensitivity--display high anxiety sensitivity like that of patients with panic disorder, according to findings by Poonai et al. Both conditions include symptoms of chest tightness, breathlessness, palpitations, apprehension, and avoidance of situations in which the symptoms occur.

Thirty-six patients with IEI and 37 healthy control subjects inhaled carbon dioxide, which is known to reproduce panic symptoms in patients with panic disorders. Their vital signs were then measured, and they were asked to rate sensations of panic and fear on a questionnaire.

A significantly greater proportion of the IEI group (71%) experienced panic symptoms after carbon dioxide inhalation, compared with the control group (26%). However, the two groups were similar in terms of changes in breathing rate, heart rate, and other physical measures. The rate of panic in the IEI group was similar to that found among patients with panic disorders, Poonai et al noted.

In addition, patients with IEI scored significantly higher than control subjects on the Anxiety Sensitivity Index (ASI), which is a self-reported measure of panic-related anxiety. Furthermore, the IEI patients who panicked after the carbon dioxide inhalation had a mean ASI score consistent with social phobia.

"The response to carbon dioxide suggests a tendency to overreport and possibly catastrophically misinterpret physical symptoms among IEI patients," Poonai et al noted, adding that this is also a consistent finding among patients with panic disorder. Furthermore, given that 67% of the IEI group fulfilled the criteria for a mood or anxiety disorder, the researchers suggested that a psychological assessment may be warranted for all patients with IEI.

Poonai N, Antony MM, Binkley KE, et al. Carbon dioxide inhalation challenges in idiopathic environmental intolerance. J Allergy Clin Immunol. 2000;105:358-363.

IS S AUREUS RESISTANT TO VANCOMYCIN?

Staphylococcus aureus may be developing resistance to vancomycin, warned the Centers for Disease Control and Prevention (CDC) in a report of the fourth known case of vancomycin-resistant S aureus. This is somewhat alarming because nosocomial methicillin-resistant S aureus (MRSA) is already common, and vancomycin is the last line of defense against it.

The case involved a 63-year-old woman with end-stage renal disease who had a history of frequent hospitalizations and intermittent treatment with vancomycin. Her most recent hospitalization (in April 1999) was for MRSA bacteremia, which had developed despite nearly two weeks of vancomycin therapy.

The patient continued to receive vancomycin during her stay in the hospital. Nevertheless, a blood culture 13 days after admission grew S aureus organisms with a minimum inhibitory concentration (MIC) of 4 µg/mL. The patient's median serum vancomycin concentration was 12.7 µg/mL at that time. Three subsequent blood cultures over the next three days grew S aureus with MICs of 8 µg/mL.

The patient died from endocarditis 10 days after the first culture. Subsequent testing found that her S aureus isolate was susceptible to vancomycin at a MIC of 4 to 8 µg/mL, depending on the test method that was used.

The CDC confirmed these findings and concluded that the isolate had an intermediate level of vancomycin resistance. No such S aureus isolates were recovered from other sites on the patient's body, nor was there evidence of transmission to her family members, health care workers, or other patients.

The Centers for Disease Control and Prevention. Staphylococcus aureus with reduced susceptibility to vancomycin--Illinois, 1999. MMWR Morb Mortal Wkly Rep. 2000;48:1165-1166.

TOPICAL LIDOCAINE MAY EXAGGERATE LARYNGOMALACIA

Application of topical lidocaine to the larynx may cause an increase in laryngeal collapse and stridor among some infants and children undergoing bronchoscopy. This change may exaggerate the severity of laryngeal dysfunction and possibly lead to overly aggressive treatment.

Nielson et al examined 156 infants and children referred for flexible fiberoptic bronchoscopy for a variety of indications--most commonly, wheezing, cough, and stridor. Each subject was sedated with midazolam and nalbuphine, and topical lidocaine was applied to the nasal passage to increase comfort as the bronchoscope was inserted.

The researchers scored the signs of laryngomalacia (ie, the magnitude of collapse of the arytenoids and folding of the epiglottis during inspiration) before and after spraying 1 mL of preservative-free 2% lidocaine solution onto the larynx and vocal cords. Additional doses of lidocaine were applied as necessary to achieve adequate topical anesthesia.

The laryngomalacia score was significantly more likely to increase than decrease after application of topical lidocaine. Subjects less than 100 weeks old were more likely to have laryngomalacia at baseline and to experience an increased laryngomalacia score after application of topical lidocaine than were older children.

To determine if the laryngeal changes were caused by lidocaine's anesthetic properties rather than by other nonspecific effects, 10 additional infants or children with a history and physical findings consistent with laryngomalacia were evaluated at baseline, after a topical dose of normal saline, and after a topical dose of lidocaine. While the laryngomalacia score did not change with the saline spray, it increased after the lidocaine administration.

Recurrent croup, stridor, and wheezing were all positive predictors of laryngomalacia. Nielson et al believe that each child should be considered within the clinical context. "A child who exhibits some signs of malacia after topical anesthesia, but who has no history of stridor or other abnormal breath sounds, probably does not have significant laryngomalacia," they noted.

Nielson DW, Ku PL, Egger M. Topical lidocaine exaggerates laryngomalacia during flexible bronchoscopy. Am J Respir Crit Care Med. 2000;161:147-151.