Implementing a negative-pressure isolation ward for a surge in airborne infectious patients

Abstract

Background: During a large-scale airborne infectious disease outbreak, the number of patients needing hospital-based health care services may exceed available negative-pressure isolation room capacity.

Methods: To test one method of increasing hospital surge capacity, a temporary negative-pressure isolation ward was established at a fully functioning hospital. Negative pressure was achieved in a 30-bed hospital ward by adjusting the ventilation system. Differential pressure was continuously measured at 22 locations, and ventilation airflow was characterized throughout the ward.

Results: The pressure on the test ward relative to the main hospital hallway was -29 Pa on average, approximately 10 times higher than the Centers for Disease Control and Prevention guidance for airborne infection control. No occurrences of pressure reversal occurred at the entrances to the ward, even when staff entered the ward. Pressures within the ward changed, with some rooms becoming neutrally or slightly positively pressurized.

Conclusions: This study showed that establishing a temporary negative-pressure isolation ward is an effective method to increase surge capacity in a hospital.

Keywords: Airborne infection isolation room; Biodefense; Bioterrorism; Pandemic preparedness; Respiratory infection control; Surge capacity.

Fig 1

Isolation ward layout and instrument locations. PC, personal computer; TEC, the energy conservatory; UV, ultraviolet.

Fig 2

Smoothed pressure time series of (A) outer envelope and isolation room pressure differentials and (B) internal pressure differentials. Vertical lines split pretest, ramp-up, demonstration, ramp-down, and posttest time periods. ANT, temporary anteroom; BED1, bedroom 1; BED2, bedroom 2; BED3, bedroom 3; BED4, bedroom 4; BTH1, bathroom 1; BTH2, bathroom 2; BTH3, bathroom 3; ISA, isolation anteroom; ISB, isolation bathroom; ISR, isolation room; IWH, isolation ward hallway; MHH, main hospital hallway; STR1, stairwell 1; STR2, stairwell 2; UTL, utility closet. Note. Duplicate datasets are noted with subscripts 1, 2.

Fig 3

Static pressure time series (blue markers), door opening events (red markers, gray line), trimmed mean time series (black line), and door opening event identification boundaries (green lines) for the outer pressure envelope during the negative-pressure demonstration. (A) IWH-MHH₁ (across fire doors) pressure time series. (B) IWH-MHH₂ (across anteroom) pressure time series. (C) ANT-MHH pressure time series. (D) ANT-STR1 pressure time series. (E) IWH-STR2 pressure time series. (F) ISR-IWH pressure time series. ANT, temporary anteroom; ISR, isolation room; IWH, isolation ward hallway; MHH, main hospital hallway; STR1, stairwell 1; STR2, stairwell 2. Note. Duplicate datasets are noted with subscripts 1, 2.

Fig 4

Door opening event maximum pressures and event lengths, with markers colored by the median pressure measured during the event. (A) IWH-MHH₁ (across anteroom). (B) IWH-MHH₂ (across anteroom). (C) ANT-MHH. (D) ANT-STR1. (E) IWH-STR2. (F) ISR-IWH. (G) ISR-ISA. (H) ISB-ISR. ANT, temporary anteroom; ISA, isolation anteroom; ISB, isolation bathroom; ISR, isolation room; IWH, isolation ward hallway; Max, maximum; MHH, main hospital hallway; Press., pressure; STR1, stairwell 1; STR2, stairwell 2. Note. Duplicate datasets are noted with subscripts 1, 2.