Parental report of pediatric tracheostomy care.

OBJECTIVE: There are little data on the actual care given pediatric tracheostomy patients in their homes. Information on the use of supplies and on techniques and frequency of care is valuable for a better understanding of the needs of this population. DESIGN: Questionnaires were distributed by mail or at clinic visits from May 1995 to June 1996 to a convenience sample of tracheotomized patients at the University of Michigan Pediatric Physical Medicine and Rehabilitation clinic. SETTING: Tertiary care clinic. RESULTS: Clean technique for suctioning was reported by 96.7% of subjects and the rest reported sterile technique. Fifty percent of subjects reported reusing suction catheters. Cleaning solutions used to clean suction catheters for reuse varied. Tracheostomy tube reuse was reported by 55% of subjects. Sixty percent of those who reused tracheostomy tubes had had pneumonia within the previous year, whereas only 25% of those who never reused the tracheostomy tube had pneumonia in the same time period. CONCLUSIONS: Suctioning frequency, suction catheter, and tracheostomy tube reuse and cleaning methods are variables that warrant further investigation of safety and efficacy.

Cryptogenic fibrosing alveolitis with preserved lung volumes.

BACKGROUND: Cryptogenic fibrosing alveolitis (CFA) is an uncommon disorder of unknown aetiology characterised by interstitial fibrosis which typically shows a restrictive pattern on pulmonary function testing. Some patients with CFA and relative preservation of lung volumes have been described and it has been suggested that their volume preservation may be due to concomitant emphysema. In a retrospective study the relative frequency of preserved lung volumes in CFA, its relationship to emphysema determined by CT scanning, its clinical features, and its subsequent natural history were investigated. METHODS: Using predefined characteristics 48 patients with CFA were identified from pulmonary function records over a three year period. Volume preservation was defined as a forced vital capacity (FVC) of > 80% predicted at presentation. Patients with relative volume preservation were compared with those with more typical pulmonary restriction and clinical data at presentation, and details of their subsequent prognosis, treatment and loss of lung function with time were obtained. Where available, computed tomographic (CT) scans for the two groups were compared in a blinded fashion to score the extent of fibrosis and the presence of concomitant emphysema. RESULTS: Twenty one (44%) of the patients with CFA had a FVC of > 80% predicted. They were more likely to be male (76% versus 48%) and to be current smokers (57% versus 22%) with a heavier life time cigarette consumption than the restricted patients (mean (SE) 38 (4.6) versus 25 (4.5) pack years). There were no significant differences in prognosis and subsequent treatment between the groups. Comparable HRCT scans were available in 23 subjects (seven preserved, 16 restricted). They showed no difference in extent of the pulmonary fibrosis but patients with volume preservation were more likely to show concomitant emphysema (86% versus 19%). Patients with emphysema on HRCT scans were heavier smokers (41(10) versus 21(17) pack years) than those without emphysema but there was no difference in the extent of CFA score between the two groups. CONCLUSIONS: In this area of high smoking prevalence a significant number of patients with CFA presented with relative preservation of lung volumes and FEV1/FVC ratio. In many of these subjects this appears to reflect coincidental emphysema. This may make interpretation of gas transfer factor used to monitor progression in CFA difficult. However, there was no evidence that lung volumes at presentation were of prognostic significance.

Role of charge suppression and ionic strength in free zone electrophoresis of proteins.

The free zone electrophoretic mobility of proteins can be predicted from the protein's amino acid content by applying a model based on the Debye-Hückle-Henry theory and Henderson-Hasselbalch equation. Calculated mobilities are always greater than actual mobility but a pH-independent proportionality (described by the constant FZ) is found between the two. Thus, determination of a protein's mobility at one pH allows, with the use of the model and FZ, calculation of its mobility at other pH conditions. This leads directly to optimum conditions for the electrophoretic resolution of proteins in capillary zone electrophoresis. The fundamental nature of FZ is examined and found to be a function of a proteins molecular weight, charge, and solution ionic strength. This work aids in explaining the form of previously proposed empirically based equations for peptide and protein mobility.