Prolonged standing in the OR: a Dutch research study

AORN Journal,  Sept, 2007  by Paul Meijsen,  Hanneke J.J. Knibbe

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One characteristic of work in the OR is the necessity to stand for long periods of time. (1,2] Long periods of standing are viewed as a risk factor for development of musculoskeletal disorders (MSDs), especially of the legs, knees, and lower back. (3-6) Most explanations about MSDs caused by standing hypothesize that damage occurs in muscles that are placed under tension for long periods. (3) In postures adopted during standing work, many muscles, including the back muscles, are placed under continuous tension. In these muscles, the intramuscular pressure is higher than the blood pressure. While they are under tension and working, the muscles do not receive sufficient blood supply and will acidify. (7) Fatigue and muscle pain are the short-term effects that can occur in only a few minutes, but an individual can reduce these effects by interrupting the static posture or changing the posture. If limits are exceeded on a regular basis, however, over time, irreversible changes may occur in the muscle tissue and tolerance for pain and fatigue can become lower. (8)

During prolonged standing, continuous concentrated compression on small, load-bearing regions of the knee and hip cartilage also can cause local disruptions to the blood supply and wear and tear on the cartilage. When static postures are maintained for long periods, synovial fluid is pressed out between the surfaces of the joints. This means that when one moves again, there is, temporarily, less lubrication of the joint. The chance of wear thereby increases. (3)

This article describes one of three studies in a research program on physical stress among operatieassistenten in Dutch hospitals. The first study in this project was an investigation of the nature and scope of MSDs among operatieassistenten. (9) In a cross-sectional survey of 463 participants in 16 Dutch hospitals, a high prevalence of MSDs was observed in comparison to MSDs in the general population. The relationship between work in the OR and MSD incidence was perceived to be strong.

Because lengthy periods of standing and awkward positions were seen as the main causes of the MSDs, two follow-up studies were planned, with the goal of being able to develop a targeted injury prevention policy. This article describes the second study in the project: a cross-sectional, multicenter study on prolonged standing in the OR.

STANDING GUIDELINES

In the Netherlands, considerable attention is given to working conditions in hospitals. Among other things, a package of practical guidelines for reducing exposure to physical stress has been developed. These guidelines are supported by the results of scientific research, and they were originally derived from international standards and directives from the European Commission. (4) The guidelines are not compulsory but are strongly recommended and are becoming more widely known. The Dutch Labour Inspectorate performs inspections based on these guidelines.

One guideline pertains to standing work. This practical guideline was developed as a stoplight model that makes a distinction between three levels of risk (ie, green, amber, red). The stoplight model comprises two constituent standards relating to uninterrupted standing time and to total standing time:

* not standing for longer than one uninterrupted hour and

* not standing for more than four hours in total per working day (Table 1). Green indicates that continuous and total standing times are within the guidelines, and there is no risk to speak of. Exceeding one of the constituent standards results in an amber classification. Amber indicates that there is a slightly enhanced risk of strain and a slightly enhanced health risk. If both standards are exceeded (ie, the red level) there is an enhanced risk of strain and an enhanced health risk, and measures to reduce the strain should be taken immediately.

If a standard is exceeded, the most effective approach is to handle the problem at the source (10) (eg, by reducing standing time immediately). Handling the issue at the source also is stated as the first-choice solution in the Dutch Occupational Health and Safety Act. (11) Traditional solutions, such as posture training, and aids, such as pressure stockings, are second-choice solutions that may only be deployed after the stress has been decreased to an acceptable level or when a source-based approach is not reasonably feasible. After all, using these aids could even lead a person to increase his or her standing time, even though the stress placed on the muscles is seldom reduced using these measures. The preventive effects of other measures aimed at reducing excessive static stress at work, such as corporate fitness or sports programs, have not been proven. (12,13)

PURPOSE OF THE STUDY

The purpose of this study was to gain insight into the stress caused by standing work. In particular, this study sought to determine the extent to which the practical guideline concerning standing is exceeded. With the help of the data collected, possible solutions can be explored. The practical guidelines were introduced one year earlier, and at the time of the research study, they were not widely known among operatieassistenten.