Shewhart control charts in relation to patient rehabilitation in healthcare

Source: [2] - W. Edwards Deming, “Out of the Crisis: A New Paradigm for Managing People, Systems and Processes” / “Out of the Crisis”, W. Edwards Deming. Correction of Russian translation (for greater clarity): Scientific Director of the AQT Center Sergey P. Grigoryev .

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After the operation, the patient must learn to walk again. The training takes place in a special room in a hospital in Osaka.

Figure 1 shows patient-specific data. The time taken to move the left leg from floor to floor with each step was recorded using an electrical signal. Ten consecutive steps (from the 21st to the 30th of 50 steps) give the mean X and range R of a subgroup of size n=10. Twenty such subgroups of patient observations form 20 mean X values ​​and 20 subgroup ranges.

The control limits for the X-map of mean subgroups with size n=10 are calculated in the usual way from the average range of 20 subgroups. The chart of subgroup ranges is not shown in the article.

Rice. 1. Average values ​​for a patient learning to walk after surgery. Source: Shunji Hirokawa and Hiroshi Sugiyama “Quantitative gain analysis”. – Osaka University Technical Report, Faculty of Technology 30, No. 1520 (1980).

The patient, as we see, before the start of classes was very far from a statistically controlled state; showed the best results after training for 10 days; improved previous indicators and is ready for discharge after training three weeks from the start of training, having reached a statistically controlled state.

A control chart used in this way is an important management tool in a hospital. The doctor teaches the patient until the teaching helps him, and stops teaching when his continuation no longer helps the patient.

In other words, the checklist takes the patient's best interests into account and ensures the best use of the physician's time. A good physiotherapist is a rarity in any country.

The state of statistical control has been achieved, but the output of the process is unsatisfactory. In this case, as in many others, the first step is to carefully study the control data.

For example, in manufacturing, a worker whose performance is unsatisfactory but within statistical control poses a problem. Attempts to retrain him usually turn out to be cost-effective. It is more expedient to transfer him to a new job, providing him with good training in the new place.

Advantages of Shewhart control charts for attending physicians

1. Visually maintaining a control chart directly by the attending physician helps to carry out objective operational monitoring of the patient’s condition and easily distinguish random changes in the patient’s condition from changes that require special attention (separation of signals from noise).

2. Control charts help track the effectiveness of rehabilitation procedures, allowing you to understand when the result of the applied methods has reached its maximum (stability) and the use of new rehabilitation methods will be required for further improvements. See description above (Figure 1).

3. Objective assessment of measuring systems for calculations and measurements used by doctors and laboratory technicians (stability, error, bias) to make a decision on the suitability of measuring systems (methodology, device, personnel qualifications) before monitoring the condition of patients with their help.

4. The results of controlled patient parameters, data from laboratory tests, computed tomography (CT), as well as data recorded by ventilators of intensive care patients can serve as a source of data for Shewhart control charts.

5. The attending physician can display all changes in treatment on a control chart, and the control chart will allow one to determine the identified, and not the expected, degree of their influence on the patient’s condition.