Hospital maintenance engineers are responsible for maintaining the extensive heating, air-conditioning, refrigeration, and ventilation systems in hospitals...... They start up, regulate, shut down, or repair this equipment. They manually operate equipment, make adjustments, and regularly check safety devices.
You may call them simply doctors. But most doctors have extra expertise in one type of medicine or another. In fact, there are several hundred medical specialties and subspecialties. Here are the most common types of doctors you'll likely see.