High‐frequency ventilation with the Dräger Babylog 8000plus: measuring the delivered frequency

Background: Ventilator frequency is one of the determinants of tidal volume delivery during high‐frequency ventilation. Clinicians increasingly use data on ventilator displays to inform their decisions. Aim: To measure the frequencies delivered by the Dräger Babylog 8000plus ventilator when used in high‐frequency mode. Methods: Ventilator waveforms using a test lung were recorded at the full range of settings 5–20 Hz using Spectra software at 1000 Hz. The changes in frequency produced by a 1‐ Hz change in set frequency were calculated. Actual and displayed frequencies were compared. Results: For settings up to 12 Hz, median (range) difference between set and delivered frequencies was 0 (?0.4 to +0.1) Hz. Above 12 Hz, delivered frequency varied by ?0.3 (?1.9 to +0.3) Hz. For 1‐ Hz changes in frequency settings, in the range 5–12 Hz, 1‐ Hz changes produced a change in delivered frequency of 1.0 (0.6–1.4) Hz. Above 12 Hz, the corresponding changes were 0.7 (0–2.9) Hz. The ventilator displays the set frequency during operation rather than the delivered frequency. Conclusion: At 12 Hz and below, the differences between set and delivered frequencies were relatively small compared with those at 13 Hz and higher. Above 13 Hz, the difference between set and delivered frequencies was up to 2.9 Hz. Some frequency setting changes did not result in a change in delivered frequency.     

Conceptual issues specifically related to health-related quality of life in critically ill patients

During recent years increasing attention has been given to the quality of survival in critical care. Health-related quality of life (HRQOL) is an important issue both for patients and their families. Furthermore, admission to the intensive care unit can have adverse psychological effects in critically ill patients. Recent studies conducted in critically ill patients have measured HRQOL. However, usually absent from such reports are evaluations of conceptual issues, addressing factors such as why HRQOL should be measured in critically ill patients, how to define and standardize domains of HRQOL, whether proxies can provide useful information about HRQOL in critically ill patients, whether response shift occurs in critically ill patients, and whether post-traumatic stress disorder (PTSD) occurs in critically ill patients. Some studies reported moderate agreement between patients and their proxies, although lower levels of agreement may be reported for psychosocial or physical functioning. Response shift (adaptation and change in perception) appears to be an important phenomenon and likely to be present, but it is seldom measured when estimating HRQOL in critically ill patients. Furthermore, vigilance for symptoms of PTSD and early interventions to prevent PTSD are needed.     

Pathway analysis of gene signatures predicting metastasis of node-negative primary breast cancer

Background  

Published prognostic gene signatures in breast cancer have few genes in common. Here we provide a rationale for this observation by studying the prognostic power and the underlying biological pathways of different gene signatures.     

Maternal HIV infection, drug use, and growth of uninfected children in their first 3 years

OBJECTIVE: To determine the separate effects of maternal HIV infection and drug use during pregnancy on growth of uninfected children in their first 3 years. DESIGN: Retrospective analysis of measurements from health visitor records made during routine child health surveillance at 6 weeks, 10 months, and 3 years of age. Multilevel analysis allowed for between-infant variation in fitted growth lines, and adjustment for other factors. Growth was described in terms of an intercept (z score at term) and growth slopes (change in z score per year) up to, and from, 4 months. SUBJECTS: 290 case babies delivered in Edinburgh hospitals to women who reported injection drug use by either themselves or their HIV infected partner, and 186 community controls. A total of 131 (45%) of the case babies were born to women who used drugs, predominantly opiates, during pregnancy and 93 (32%) to HIV infected women. The eight infected children were excluded from analysis. MAIN OUTCOME MEASURES: Age and sex standardised z scores for height, weight, and body mass index. RESULTS: 459 (96%) of the 476 records for cases and controls were traced, yielding 1432 weight and 939 height measurements. Maternal HIV infection was not found to affect growth; at 3 years the estimated effect on weight z score was 0.16 with 95% confidence interval (-0.25 to 0.57) and for height 0.18 (-0.19 to 0.55). Drug use during pregnancy was associated with lighter babies at 40 weeks followed by depressed growth in the first four months, these infants remaining just slightly smaller at 3 years with an estimated effect on z scores of -0.5 for weight with 95% confidence interval (-0.89 to -0.11) and -0.37 (-0.72 to -0.02) for height. CONCLUSIONS: Maternal HIV infection does not adversely affect growth in uninfected infants, and the effect of drug use during pregnancy is limited to small decrease in size at 3 years.     

Twins and twin families. A practical guide to outpatient management

Little has been written of a practical nature to guide the health professional in providing advice and support to families with twins in the practice setting. This article provides an overview of issues and concerns specific to twins and provides practical guidelines for caring for twins and their families.     

Correlation of nasopharyngeal and conjunctival cultures with middle ear fluid cultures in otitis media. A prospective study

Eighty children with acute otitis media (AOM) were prospectively studied to determine the correlation and clinical usefulness of nasopharyngeal (NP), conjunctival (CONJ), and middle ear fluid (MEF) cultures. NP cultures correlated more accurately with MEF (p less than 0.01) than did CONJ cultures (p less than 0.05) for both Streptococcus pneumoniae and Haemophilus influenzae (H. flu). The positive predictive value of NP cultures for positive MEF was only 47%, but the negative predictive value was 87 percent. NP cultures, therefore, appear to have significant predictive clinical value only when negative in identifying children likely to have sterile MEF. High correlation of NP, CONJ, and MEF in children with H. flu conjunctivitis (p less than 0.01) suggests that early systemic rather than topical antibiotic treatment for H. flu conjunctivitis in small children may avert subsequent occurrence of the "conjunctivitis-otitis" syndrome.     

Respiratory syncytial virus infection in children with bronchopulmonary dysplasia

Little is known about the risk of severe illness from respiratory syncytial virus infection in children with bronchopulmonary dysplasia. A prospective study was done of the natural history of respiratory syncytial virus infection in 30 children less than 2 years of age with bronchopulmonary dysplasia who were in a home oxygen program. Surveillance to identify children with acute respiratory symptoms was done by weekly telephone interview. Symptomatic children were examined, oxygen saturation was determined by oximetry, and nasopharyngeal lavage fluid was collected for virus cultures and rapid respiratory syncytial virus antigen tests. During the 4-month study period (December to April), 27 children had one or more acute respiratory illnesses, and respiratory syncytial virus developed in 16/27 (59%). Passive smoking and greater than or equal to four members in the home increased the risk of symptomatic respiratory syncytial virus (P less than .01 and P less than .03, respectively). Of 16 children, 11 (69%) required hospitalization. Of the 11 hospitalized children with respiratory syncytial virus, nine were either still receiving oxygen at home or required oxygen therapy within the previous 3 months v none of five nonhospitalized children (P less than .005). Five of the hospitalized children were greater than 12 months of age and five had respiratory syncytial virus infection previously that had been confirmed by culture results. Hospitalizations were prolonged and complicated. Seven of 11 children were hospitalized for greater than 1 week; four were admitted to the intensive care unit; four were treated with ribavirin aerosol, and two needed mechanical ventilation. There were no deaths.(ABSTRACT TRUNCATED AT 250 WORDS)     

Identification of the human P450 enzymes involved in the in vitro metabolism of the synthetic steroidal hormones Org 4060 and Org 30659

1. The type of human P450 enzymes involved in the in vitro metabolism of Org 4060 and Org 30659, two synthetic steroidal hormones currently under clinical development by NV Organon for use in oral contraceptive and hormone replacement therapy, was investigated. 2. Both steroids were mainly hydroxylated at the 6beta-position in incubations with human liver microsomes. 3. The results from experiments with supersomes, correlation studies as well as inhibition studies with ketoconazole, a selective inhibitor of CYP3A, strongly suggest that the CYP3A family plays a significant role in the 6beta-hydroxylation of both steroids. 4. Measurements of kinetic parameters of P450 enzymes that could metabolize both steroids, combined with the fact that CYP3A4 is known to be the most abundant P450 enzyme in the human liver, indicate that CYP3A4 will be of major importance for the in vivo human metabolism of Org 4060 and Org 30659.