A systems analysis approach to postoperative wound infections
Merrill A. Ritter, M.D.
Jack B. Hart, Ph.D.
Morris L. V. French, Ph.D.
Harold E. Eitzen, Ph.D.
Is the environment a significant factor in a postoperative wound infection, and if so, is laminar air flow an effective control? A problem of this magnitude can only be solved by the amalgamation of three basic interdisciplinary sciences: engineering, microbiology, and medicine. Working together, a systems analysis approach was developed to solve just such a problem.
A conventional 20 by 20 foot operating room was first equipped with a horizontal wall-less laminar air flow unit.* This unit was selected because of the relatively low cost and ease of installation and modification. The floor of the operating room was marked with locating spots at the nodes of 1 foot squares. Planar air velocities were measured with a single wire constant temperature, hot wire anemometer (DISA S & B Inc., Model 55D01). The anemometer probe was mounted in an indexing head attached to a locating stand. The anemometer was calibrated before and after each set of data was obtained. Ten readings, each separated by five time constants, were recorded over each locating spot with the indexing head set at each setting of —45°, neutral, and +45°. The same readings were obtained for each locating spot throughout the room. All measurements were at the 4-foot level (wound height). The results showed, that with the room empty there was a 6-foot wide area in which the air was directed away from the filter module, and at a speed of about 300 feet per minute (Fig. 1). When the room was manikin staged, the. . .