Ventilators designed to provide automated ventilatory support to patients during interhospital or intrahospital transport and in emergency situations. The operation and control of these ventilators are intentionally simplified; they are compact, lightweight (i.e., less than 5 kg), rugged devices. Most transport ventilators provide mandatory breaths at preset intervals (control mode), not allowing the patients to breathe spontaneously; operation in assist/control and/or synchronized intermittent mandatory ventilation (SIMV) modes is available in some models. These ventilators usually include an airway pressure monitor and low- and high-pressure alarms. Transport ventilators may be used in vehicles, ambulances, and in field hospitals for medium-term ventilation.