Mechanical Ventilator Malfunctions: A Descriptive and Comparative study of 6 Common Ventilator Brands

Abstract

Background

Estimates suggest that there are as many as 50,000 mechanical ventilators in use in the United States alone. Yet, the medical literature is nearly devoid of information describing or dis- cussing the issue of ventilator malfunctions. The purpose of this study was to investigate how and what types of mechanical ventilator malfunctions occur, whether there are significant differences in the malfunction rates of 6 common ventilator brands, and whether there are differences in ventilator purchase prices and long-term maintenance costs. MATERIALS AND

Methods

A retrospective review was done using hospital repair, maintenance, and billing records between July 1, 1991, and January 3, 1999. A total of 75 individual ventilators of 6 different brands were followed: 13 Bear Medical Cub ventilators (CUB), 11 Mallinckrodt Nellcor Puritan Bennett Infant Star ventilators (STAR), 8 Bird VIP ventilators (VIP), 11 Bird 6400ST ventilators (6400ST), 16 Bird 8400STi ventilators (8400 STi), and 16 Mallinckrodt Nellcor Puritan Bennett 7200ae ventilators (7200ae). The dependent variable was the operating time before malfunction, which was determined by the difference between hours logged on each ventilator's hour meter at the time of malfunction and that recorded at the outset of the study. Thereafter (when applicable), the time before malfunction was the difference in hours at successive malfunctions. Malfunctions were of 2 types: mechanical failures and operator errors. Price and main- tenance information was obtained by personal communication.

Results

In 2,201,771 hours of ven- tilator operation, only 282 malfunctions were reported; of these, 176 were classified as mechanical failures, 106 as operator errors. There were no documented instances of long-term patient harm sec- ondary to any type of ventilator malfunction. There were significant differences between some of the ventilator brands in the frequency of mechanical failures, operator errors, and the number of overall malfunctions experienced. There were also small differences in long-term maintenance costs, while purchase prices showed a considerably larger range. Curiously, modern ventilators may not suffer an increasing rate of malfunction as they age. Finally, if these 75 ventilators are representative of ventilators in general, modern ventilators may be as prone to human errors as were their predecessors.

Conclusions

The data suggest that modern mechanical ventilators are rugged and safe, but not necessarily easier to use. Comparing differences in malfunction rates, maintenance costs, and purchase price offers hospitals a pow- erful tool for reducing the costs associated with mechanical ventilation. Furthermore, if the trend toward fewer malfunctions as a ventilator ages is validated, hospitals might wish to consider maintaining ventilators longer before replacing them.