Structural Risk Factors for Hospital-Acquired Infections in Intensive Care Unit

Space

The presence of various medical devices such as hemodynamic monitoring equipment, ventilators and dialysis machines, pendants (supporting structures or beams) holding the intravenous infusion pumps, feeding pumps, temperature regulating machines, and the ICU bed can lead to a cluttered environment posing difficulties in adequate disinfection of high touch surfaces harboring multidrug-resistant organisms (MDROs; Rao et al., 2020). This congestion may be alleviated to some extent by the use of single patient rooms or cubicles (rather than multibed rooms or partitioned bays) with at least 200–250 sq. ft. per patient with adequate sunlight (“Facilities Management and Design,” 1992). Various societies have specified the minimum spacing requirements per patient: ESICM recommends 20 m² per patient in a multibed room and 25 m² per patient in a private room (Valentin & Ferdinande, 2011), and SCCM (Thompson et al., 2012) recommends 25 m² per patient in a multibed room and 28 m² per patient in a private room with optimal clearance of not less than 4 ft. at head end and foot end of the bed and not less than 6 ft. on each side of the bed (Rao et al., 2020). Apart from this, dedicated space is required for nursing station, dirty and clean utility, laboratories, storing equipment, pantry services, supply and service corridors, patient transportation routes along with lifts, heating ventilation air conditioning/heating ventilation and air conditioning system (HVAC) systems, electrical outlets, family support zones, and recreational zones (Ferdinande et al., 1997; Rao et al., 2020).

Single Room Versus Multioccupancy Rooms

Single bed rooms are strongly recommended from an infection control perspective in ICU where patients are likely to be harboring MDROs as they are easier to isolate and disinfect rather than in multioccupancy rooms (Joseph, 2006; Minimum requirements for infection prevention and control programmes , 2019). Few previous studies suggest that architectural modifications such as conversion of open rooms to enclosed isolation rooms with handwashing facilities in each room can reduce the rate of colonization and infections (Mulin et al., 1997).

Waste Disposal Systems

The ICU cubicles should be equipped with hopper systems for waste disposal and wash basins for hand wash inside the cubicle itself (Thompson et al., 2012). By reducing spillage of infective waste (stool, urine, nasogastric aspirates, and so on) to the dirty utility zone of the ICU complex, individual waste disposal systems curb infection spread in the ICU.

Surroundings Similar to Modular Operating Room (OR)

As critically ill patients who are on high organ supports (severe oxygenation failure on ventilator, high inotropic/vasopressor supports, renal replacement therapies) pose a tough challenge in getting transported to ORs and given the scarcity in OR availability, many operations can take place in the same ICU cubicle with all the armamentarium required for surgery accommodated in the same space. Therefore, each ICU cubicle should ideally be structured and designed as a “procedure ready ICU” or “modular ICU” resembling a modular OR (Regli & Takala, 2005).

Walls, Roof, and Floors

It is necessary to use construction materials (paints, varnishes, steel), with smooth, nonporous, and seamless finishing (Eileen Malone et al., 2011). Additionally, these should be tested for their compatibility with hospital-grade detergents, cleaners, and disinfectants used in ICU. Stainless steel (SS) of SS 304 and above is a preferred material for construction of the roof due to resistance to rust, moisture, and humidity that occur in ICU ( Medical Applications of Stainless Steel 304 [UNS S30400], n.d.). Epoxy or polyurethane-coated flooring can make the cleaning process of the floor easier, as these coatings offer seamless finishing and high mechanical strength and resistance to a large number of chemicals such as solvents and acids (Epoxy Flooring versus Polyurethane Flooring|Industrial Flooring by Reepol, n.d.). Further advantages include ease of cleaning and lower microbial adherence on the floor (Floor for Hospitals and Healthcare Facilities—Seal-Krete High Performance Coatings, n.d.).

Furniture

Porous materials and exposed wood surfaces retain moisture and support the growth of microorganisms. Furniture with embellishments (drawer pulls, multilevel surfaces) are difficult and time-consuming to clean thoroughly (Eileen Malone et al., 2011). Likewise, seams trap microbes and are inherently difficult to clean. The disinfection of furniture components and other decor in ICU is essential for the prevention of HAI as these can potentially carry a huge bioload of microorganisms (“Facilities Management and Design,” 1992). Metal and hard plastic-based furniture with copper or nano coating to reduce the antimicrobial adherence are preferred as they are easy to clean and less likely to support the growth of microorganisms. (Eileen Malone et al., 2011).

Role of Intelligent Materials

Traditional construction materials such as partition glass are associated with various problems such as transparency (disturbs patient privacy), cleaning issues, and visual issues due to glare. In the case of concrete, efflorescence and mold discoloration can cause cosmetic, allergic, and internal structural issues due to excess humidity. Likewise, false ceilings and cladding material can occasionally release toxic substances. Recent advancements in this area are the use of “intelligent” materials in construction, labeled as “welfare”: a technology enhancing patient well-being, by improving the surroundings in a heathcare building (Mohamed & Shiha, 2019). Intelligent materials have the ability to perform sensing and actuating functions, similar to living systems. With external stimuli, the sensor will deliver the input to the material which affects its internal energy and alters its microstructure, which results in the change in the materials property. A typical example of such material is the partition glass which can transform from opaque to transparent based on electronic command. Apart from these, recent advancements in nanotechnology include application of nano coatings made of silver, titanium oxide, zinc oxide, and cero-oxide offering antibacterial properties (Mohamed & Shiha, 2019; Webster & Taylor, 2011). These materials also offer easy cleaning and disinfection, providing a healing environment and a structural guard for the most vulnerable patients (Huisman et al., 2012).

Microclimatic Factors

Various microclimatic parameters such as relative humidity, temperature, and airflow pattern play key role in pathogen transmission and are controlled by the HVAC system (Curtis, 2008; Saran et al., 2020).

Air Change Rate

Various society guidelines suggest that maintaining full fresh flow with at least 20 air changes per hour (ACH) and laminar air pattern from clean to dirty zones is preferable to recirculation type HVAC is preferable to recirculation type HVAC with 6–8 ACH and can reduce HAIs including pneumonias (Saran et al., 2020).

Maintenance of Ventilation Systems

Many infections like Aspergillus, MRSA, and Clostridium difficile have been linked to poorly functioning HVAC systems. Microorganisms were isolated from cooling ducts, air filters named as “filter forensics” (Saran et al., 2020). Regular maintenance of high-efficiency particulate air filters (HEPA) and HVAC plant as per prescribed standards is essential.

Special Air Distribution Systems

It is advisable to isolate patients with pulmonary tuberculosis, coronavirus disease 2019 (COVID-19), and those harboring MDROs in “negative pressure isolation rooms” to minimize spread of infections to other patients and healthcare workers and to isolate heavily immunosuppressed patients (on cancer chemotherapy, posttransplant) in “positive pressure isolation rooms” to prevent spread of infections from others. Also, frequent IAQ testing should be carried out to ensure planned preventive maintenance of HVAC system (Saran et al., 2020). During the current pandemic of COVID-19, a severe scarcity of negative pressure rooms or air-borne infection isolation rooms (AIIRs) has been noted. Various stopgap measures have been sought to combat the scarcity of AIIRs to create temporary negative pressure isolation rooms by altering supply air to a lesser value than the sum of return and exhaust air (SA < [RA + EA]) by retrofitting: fitting a high-power exhaust (Ahlawat et al., 2020) or by using portable HEPA-filtered forced air units (Saran et al., 2020).

Intelligent HVAC Systems

These systems can sense the interaction between user and the environment and modify it according to the needs, minimizing energy consumption (Allen et al., 2015; Reijula et al., 2013).

The components of structural risk factors that we have discussed pertain mainly to the designing phase of ICUs, and although guidelines from various societies do mention the role of such risk factors, they need to be incorporated more stringently in practice (Guidelines for Environmental Infection Control in Health-Care Facilities: Recommendations of CDC and the Healthcare Infection Control Practices Advisory Committee (HICPAC), n.d.; Yokoe et al., 2014).