Clinical engineering Lecture (8)

Safety program Types of hazards present in hospitals: The clinical engineer is a key figure in establishing a safe environment in the hospital. While physicians, nurses, and other medical personnel are busily serving patients under their care, the clinical engineer must focus on hazards that may disrupt or destroy the life-saving efforts of this medical staff.

The hazards present in the hospital are widespread and complex: Electrical hazards Mechanical hazards Environmental hazards Biological hazards Radiation hazards

Electrical hazards Electrical hazards are insidious and pervasive. Electrical energy, if allowed to flow to sensitive body organs at current levels below 20 micro A. Aside from shock hazards, electrical energy is an ignition source for fires in the hospital.

Mechanical hazards Mechanical devices are necessary for many treatments in hospitals. These devices include mobility aids, transfer devices, mechanical assist devices, and patient support equipment. Each of these devices embodies numerous threats to the life of patients and hospital staff. These devices must be subject to careful design review, failure indication, and the establishment of complete specifications for safe use.

Environmental hazards The environment within the hospital is critical for life support and rapid patient recovery. Such elements as solid wastes, noise, utilities (natural gases, water), and structural aspects of the hospital building must be carefully controlled and managed to reduce hazards from the spread of infection as well as injury from physical objects.

Beyond this, the hospital must exist in the community environment and solid wastes and air pollution are a significant output requiring the attention of the entire hospital staff with advice and recommendations from the clinical engineer.

Biological hazards Infection control is obviously a major factor in hospital safety. Infection control is approached by a sampling and evaluation program to identify exposures followed by identification and elimination of sources. Sterilization is a primary tool in infection control, and it must be carefully evaluated in clinical engineering programs.

Radiation hazards Radiation and radioactive materials have assumed a broad role in medical treatment. The health hazard of these devices and substances requires the establishment of programs to control the use of diagnostic machines and therapy devices to prevent the unwanted release of ionizing radiation.

Waste control is especially critical with radiological substances because of the extended periods during which these substances remain hazardous. The clinical engineer must have knowledge of the physics of ionizing radiation and its control to formulate and supervise control systems.

Principles of electrical safety The effects of the electrical current on the human body are a function of the resistive paths of the body. the frequency of the applied voltage or current, the current path, the length of time that the current flows through the body, and finally the overall physical condition of the person.

Macro shock: In the case of macro shock, currents greater than 0.5mA passing through the body. Large currents cause paralysis of the respiratory muscles due to continuous contraction of the chest muscles, respiratory failure due to damage of the central nervous system or neural inhibition.

Micro shock: Micro shock is defined as currents normally less than 1mA that enter the body at the heart through an invasive device. The primary reaction that can occur is circulatory failure due to ventricular fibrillation (unsynchronized contraction of the muscle fibers).

Procedures that make a patient susceptible to micro shock include: The insertion of a catheter from an external pacemaker. Insertion of an electrode into a heart chamber for intra-cardiac ECG measurements