A Random Survey of Anesthesia Machines and Ancillary Monitors in 45 Hospitals

Abstract

One hundred sixty-nine anesthesia machines and ancillary monitors were tested in 45 hospitals, randomly selected to assure a sample of hospitals with a wide range of anesthesia workload. The machines ranged in age from 1 to 28 years (8 ± 6, mean ± SD), with 47.3% manufactured since 1980, 39.1% between 1970 and 1980; and 13.6% before 1970. Regular maintenance was provided for 112 machines (66.2%) by the manufacturer, whereas 55 machines (32.5%) were maintained by independent contractors. Two machines designated as backup machines received no maintenance. There was no source of oxygen to back up oxygen piped from a central source on five machines. Thirteen machines had leaks over 500 ml/min distal to the common gas outlet, the most common sites being the carbon dioxide absorber, dome valves, and oxygen monitor sensor adaptors. Another two machines had leaks over 500 ml/min proximal to the common gas outlet. Forty-two of the 169 machines did not have an oxygen analyzer; another 18 had oxygen analyzers that did not function properly. Only 29 (23.5%) of 123 machines equipped with a ventilator had a working high-pressure alarm, whereas functioning low-pressure alarms were available on 104 machines (84.5%). Fourteen of the 383 vaporizers tested for calibration did not meet the calibration standard recommended by the manufacturers. None of the 32 liquid anesthetic samples collected and analyzed during the survey showed contaminants. Only four (8.8%) hospitals utilized a written anesthesia machine checklist. There was no correlation between the number of malfunctions observed and ages of the machines, although the older machines tended to lack the basic monitoring devices and safety features. Equipment inadequacies encountered during the survey period ranged in degree of severity. All such inadequacies were pointed out to the facilities involved. Those inadequacies considered to be major in nature have been rectified.