Jeffrey R. Budd

Feasibility and compliance studies of a home measurement monitoring program for cystic fibrosis

A home measurement monitoring system has been developed for assessing progress and planning changes in care for patients with cystic fibrosis. Daily diary recording of specified measurements, quantitative symptom data, and free text are to be used for early detection of deteriorating trends before serious complications develop. Daily measurements made at home are lung capacity, body weight, breathing rate, and pulse. The program has been in place for the past two years, and has maintained a 75-80% consistent diary response rate among the 111 patients initially committed to the program. Measurements are easy to perform, equipment design is simple and rugged, and data handling routines designed for the program using the INSIGHT clinical data base system perform satisfactorily. Checking for data entry errors and validity checks of home measurements are a regular part of the data handling activity. Patient acceptance and long-term compliance in this program agrees very favorably with reports of other diary programs in chronic disease. Diary compliance was significantly greater among younger patients and those who lived long distances from the hospital. This study has demonstrated that home monitoring is a feasible program for patients with cystic fibrosis. It presents the possibility of detecting adverse health trends earlier than is now practical, so that patients can be treated before serious complications develop, thereby preventing the large fluctuations in health status that often accompany CF.

A medical information relational database system (MIRDS)

A medical information relational database system (MIRDS) which is resident on a relational database machine and is accessed via microcomputers has been created for a pediatric pulmonary division of a research hospital. The power and flexibility of MIRDS has permitted the integration of clinical tasks, research interests, and laboratory functions. Procedures have been devised to assure data integrity, allow flexibility in data retrievals, produce standardized report formats, and permit data access for users with a wide range of query expertise. There are few impediments to the integration of additional clinical, research, and laboratory functions as the system evolves.

A rule for the early detection of chronic changes in cystic fibrosis patient status

A statistical decision-making system has been developed which will predict the clinical status of a patient with cystic fibrosis based on daily self measurements obtained at home. The data for the study were collected from CF patients within 7-12 years of age. Thirty-two participants recorded four daily measurements (weight, vital capacity, breathing rate, and resting pulse) and one weekly measurement (height). In addition to the 4 daily measured values, the clinical status of each patient at his/her most recent previous clinic visit was used as a predictor variable. The measured values were used as the basis for the development of a discriminant rule. The goal of the rule was to determine whether each patients clinical status was deteriorating, stable, or improving at the time of the most recent set of weekly measurements. Three types of analysis were performed: linear discriminant analysis, quadratic discriminant analysis, and nearest neighbor. Quadratic discriminant analysis provided the best discrimination due to the differences in the covariance matrices among the populations. The rule was able to correctly classify 77% of the 103 cases in the learning set. To further evaluate the rule, both a weighted classification percentage and weighted kappa statistic were calculated for the rule. Bootstrapping was used to predict the performance of the rule on the population with results of 77% correctly classified overall.

An Evaluation of Incentive Inspirometers for Following Pulmonary Function by Self-Measurement in the Home

Measurements of inspired vital capacity made with two commercially available, inexpensive incentive inspirometers (Voldyne, Volurex) have been compared to standard expired forced vital capacity (FVC) measured by spirometry in the pulmonary function laboratory. Reliability of self-measurement made at home with these devices was also studied. There were 119 subjects in this study with an average age of 14.1 years, (4-44 years). Home and clinic Voldyne measurements were highly correlated (r = 0.96). There were no statistically significant differences between paired measurements. Although differences between inspired vital capacity using either device and FVC were significant (p 0.001), inspired vital capacity was strongly correlated with FVC (r = 0.83 for Voldyne, r = 0.90 for Volurex). Subjects can make reliable measurements of lung capacity at home with inexpensive devices. These measurements are linearly related to standard FVC and can thus provide trend information on lung function over long time periods from an ambulatory setting. Such measurements have been used for tracking lung function in cystic fibrosis, and may be applicable in other chronic pulmonary diseases.

Automation in high frequency chest compression

The high frequency chest compression (HFCC) device was designed to aid in mucous clearance for cystic fibrosis (CF) patients It consists of a large variable volume variable frequency air pulse delivery system and a non-stretchable inflatable vest (BDV) worn by the patient. A software package to tune this device baa been implemented in C. The new software has automated the tuning process by its capacity to automatically control the frequency of the alternating frequency device (pump). Calibration of frequency control has been automated with a view of keeping the tuning routine independent of the pump controller in use, given that the controllers operating characteristic was linear.

Measuring gas exchange and gas mixing in children

A pulmonary function test has been created to measure gas mixing, gas exchange, and flow parameters during tidal volume breathing (TVB) in patients from preschool age to adulthood. This short, effort independent TVB test was made possible by applying a simple lung model, using a multigas analyzer, eliminating valve dead space, dynamically adjusting for flow-gas lag and response time, and correcting for some of the problems of testing children.<<ETX>>