An expanded scoring system including an index of nutritional status for patients with cystic fibrosis.

Evaluation of success or failure of therapy for patients with cystic fibrosis (CF) commonly relies on the results of a single pulmonary function test (PFT). Most PFT measurements reflect different functional aspects of the lung. Although no single parameter can summarize all aspects of lung function, a combination of several may provide an advantage by reflecting the overall abnormality of lung function in one number. Cropp et al. (1982, Am Rev Respir Dis 126:211-216) developed a multiparameter pulmonary function score (PFS) using the results of six separate parameters obtained from a PFT. In CF, there is also the potential for declining nutritional status (NS), leading to malnutrition and skeletal muscle wasting. Our aim was to expand the PFS by including weighted information on NS, and to determine whether the expanded score (nutritional-pulmonary function score, NPFS) was more sensitive in detecting change in outcome variables than the PFS. Individual PFT parameters, percent ideal body weight (%IBW), and an index of anaerobic performance (AP) were measured in 21 patients on admission to the hospital and again at discharge. In the group as a whole, in-hospital therapy resulted in improvement (P < 0.01) in individual PFT parameters, %IBW, PFS, and NPFS, and no change in AP. While the PFS more effectively reflected improvement in lung function than did any single PFT parameter, the NPFS resulted in an even more sensitive index of change. Based on these results, we believe that the NPFS, which includes both lung and nutritional status, provides an effective and sensitive index of disease severity that can be used as a unifying measure to: 1) detect disease progression; 2) guide rehabilitation and training; 3) stratify patients for clinical trials; or 4) evaluate the effects of a therapeutic intervention.

An in-hospital evaluation of the sonic mist ultrasonic room humidifier.

It is generally recognized that nebulizers can be a source of nosocomial infection. 'Cold mist' room humidifiers are a particular problem because they are difficult to sterilize. We evaluated a new device, the Sonic Mist ultrasonic room humidifier, to determine how quickly it became contaminated during continuous use by a population of cystic fibrosis patients. In addition, the study was designed to test the effectiveness of placing a bacterial filter on the air inlet of the humidifier. We found that the entire humidifier could withstand repeated gas sterilization. Data obtained from 18 humidifiers involving cystic fibrosis patients indicate that the earliest humidifier contamination occurred after 5 days of continuous use. Although all patients had large numbers of gram-negative bacilli as predominant sputum flora, only 7 episodes of contamination were found during 34 humidifier-use periods. Three units equipped with filters became contaminated (5-7 days) and four unfiltered units became contaminated (6-11 days), indicating that the use of an inlet filter made no apparent difference. The organisms recovered from contaminated units were not found as sputum flora and would not generally be considered of clinical significance in cystic fibrosis sputum cultures. Probable sources of the organisms were room dust and hand contamination. A further test of the inlet filter was performed by exposing filtered and unfiltered units to mist from an intentionally contaminated humidifier. Again, the contamination rate was low and the filter apparently made no difference. These results indicate that the Sonic Mist humidifier may be appropriate for hospital use if adequate sterilization and contamination-monitoring practices are followed.

Decrease in airway pressure during high-frequency jet ventilation in infants with respiratory distress syndrome.

Using a crossover study design, we compared a system of high-frequency jet ventilation with appropriate humidification to pressure-limited conventional ventilation in 12 preterm infants with a birth weight of 1.9 +/- 0.6 kg and gestational age of 32 +/- 2 weeks who had severe respiratory distress syndrome. After a control period of conventional ventilation, high-frequency jet ventilation was administered for 1 to 3 hours at a constant rate (250/min) and inspiratory to expiratory time (1:3 or 1:4) in the same fraction of inspired oxygen as during conventional ventilation. Average peak inspiratory pressure decreased from 29 +/- 3 cm H2O during conventional ventilation to 20 +/- 4 cm H2O during high-frequency jet ventilation (P less than 0.001), whereas positive end expiratory pressure was unchanged, resulting in a reduction in mean airway pressure from 14 +/- 3 to 10 +/- 2 cm H2O (P less than 0.001). There was a simultaneous decrease in PaCO2 (39 +/- 4 to 34 +/- 4 mm Hg, P less than 0.01), but PaO2 did not change. These data indicate that short-term high-frequency jet ventilation maintains gas exchange in infants with respiratory distress syndrome despite a lower PIP and Paw, and results in smaller airway pressure swings than during conventional ventilation. Thus, high-frequency jet ventilation may offer hope for reducing barotrauma in this population.

Early echocardiographic and pulmonary function findings in idiopathic scoliosis.

Thirty-six children and adolescents with early stages of idiopathic scoliosis underwent evaluation by echocardiography and pulmonary function testing. Mildly increased pulmonary vascular resistance was inferred from an elevated ratio of right preejection period to right ventricular ejection time, an increased right ventricular dimension, and a decreased left ventricular dimension. Since neither decreased arterial oxygen saturation nor increased end-tidal expired carbon dioxide partial pressure was seen, desaturation and hypoventilation should not account for these abnormalities. Pulmonary function parameters showed no distinct patterns of abnormality. Even though the patients were divided into two groups by severity of spinal curvature, the cardiopulmonary measures did not correlate with thoracic deformity. Billowing of the mitral leaflets, termed mitral valve prolapse, was demonstrated in 25% of the subjects. Our findings suggest that cardiopulmonary and thoracic changes in idiopathic scoliosis may develop in parallel and may be expressions of a common collagen defect. However, study of sleep and exercise arterial saturation may be required to rule out intermittent hypoxemia as a precipitating factor of cor pulmonale in scoliosis.

A new patient-circuit adapter for use with high frequency jet ventilators.

Current techniques of connecting a patient's endotracheal tube to the delivery circuit of a high frequency jet ventilator have several disadvantages. We describe a rigid, interchangeable adapter with a built-in jet injector that connects to any type or size of endotracheal tube. The device is reusable and avoids some of the disadvantages, such as catheter kinking, difficulty in accommodating injectors of different diameters, and tracheal tube obstruction, inherent in other commonly used techniques. It has been used successfully on 44 patients ranging in size from premature infants to adults.

Mean airway pressure: theoretical considerations.

Several recent articles have suggested the use of mean airway pressure (Paw) as an index of the physiological effect of ventilating pressures. To facilitate the understanding of this parameter, operational formulas are derived by applying the explicit, mathematical definition of Paw to several clinically relevant pressure waveforms. These formulas are then generalized to apply to any wave shape. It is shown that any pressure waveform can be characterized by a waveform constant K, knowledge of which permits the estimation of Paw using information from either airway pressure recordings or the control settings and pressure gauges on conventional ventilators.

Computer analysis of slow vital capacity spirograms.

We have developed a digital computer program which evaluates the vital capacity and its subdivisions, expiratory reserve volume and inspiratory capacity. The algorithm examines the multibreath spirogram, a continuous record of quiet breathing interspersed among repeated slow, large volume maneuvers. Quiet breaths are recognized by comparing features of each breath to the respective average and variation of these features for all breaths. A self-scaling, iterative procedure is used to identify those end-tidal points that most likely represent the subject's functional residual capacity. A least-squared error baseline is then fit through these points to partition the vital capacity. Twenty-three spirograms from patients with documented pulmonary disease were independently analyzed by the computer, a pulmonary function technician, and the laboratory supervisor. No practical differences were found among the results. However, the computer's values, in contrast to those of the technician, were reproducible on repeated trials and free of computational and transcriptional errors.