Novel bed integrated ventilation method for hospital patient rooms

This study presents a novel method for advanced ventilation of hospital wards leading to improved air quality at reduced ventilation rate. The idea is to evacuate the bio-effluents generated from patients’ body by local exhaustion before being spread in the room. This concept was realized by using a mattress having a suction opening from which bio-effluents generated from human body are exhausted. Experiments were conducted in a full-scale two-bed hospital room mock-up, 4.7 x 5.3 x 2.6 m3 (W x L x H). Only one of the patients’ beds was equipped with the ventilated mattress. The room was air conditioned via mixing total volume ventilation system supplying air through a ceiling mounted diffuser. All experiments were performed at room air temperature of 23ºC. A thermal manikin was used to simulate a polluting patient on the bed equipped with the ventilated mattress. Two heated dummies were used to simulate an exposed patient and a doctor. Bio-effluents from the body were simulated by tracer gases released from manikin’s armpits, groin region and feet. Contaminants’ distribution in the occupied zone was analyzed. The performance of the ventilated mattress was assessed based on pollution concentration in the breathing zone of the exposed patient and the doctor. Various experiments were performed at three background ventilation rates, namely 27, 55 and 109 L/s (1.5, 3 and 6 air change rates, ACH). Two openings in the mattress, located at the feet and the pelvic region, were used to exhaust the air through the mattress at 1.5 L/s. The obtained results showed that the use of the advanced ventilation together with background ventilation rate of 1.5 ACH significantly improved the air quality in the room compared to the air quality in the case of 6 ACH background ventilation only.