Examination of Changes in Infection Rates in a Restructured Anaesthesia Intensive Care Unit: A Retrospective Study

Abstract

Objective

This retrospective study aimed to evaluate the effect of a restructured anaesthesia intensive care unit (ICU) on changes in infection rates and infections.

Methods

Organisational restructuring was done in the anaesthesia ICU of Firat University Hospital after it was relocated on 14 March 2012. This study was designed to investigate the effect of restructuring on infection rates through a comparison of periods encompassing one year before relocation and one year after relocation. Nosocomial infections were diagnosed according to modified Centers for Disease Control and Prevention (CDC) criteria. In total, 406 patients who were over 18 years old and admitted to the ICU were included; they were hospitalised for 48 h or longer and had non-infectious diseases according to physical examination, laboratory and culture results on admission. The data of 214 patients (Group A) and 192 patients (Group B) were examined.

Results

Parameters such as age, gender, primary diagnosis and mean GCS score at admission and mean duration of hospitalisation showed no effect on the rates of infection, but rates of total infection (41.1% vs. 25%), urinary (18.7% vs. 10.4%) and VIP (32.7% vs. 14.6%) were detected in Groups A and B. Statistically significant differences were found for the causative pathogens Pseudomonas (15.4% vs. 6.8%), Acinetobacter (18.2% vs. 12%) and Escherichia (8.9% vs. 2.1%); the mean duration of mechanical ventilation (15.01±16.681 vs. 12.22±17.595) and discharge with improvement (31.8% vs. 44.3%).

Conclusion

We detected that restructuring (such as acclimatization, educated staff, hepa filter) caused a significant decline in infection rates. Because ICU staff may be a major cause of infection, we believe that providing education and conducting effective surveillance programs will be the most important factors for reducing infection rates.

Introduction

Nosocomial infections still remain to be an important public health concern despite all control measures taken all over the world (1). They cause prolonged hospitalization and increased mortality, morbidity and treatment costs (2). According to the definitions of The Centers for Disease Control and Prevention’s (CDC’s) and National Nosocomial Infections Surveillance (NNIS), nosocomial infections acquired in the intensive care unit (ICU) do not exist at the time of admission to the hospital, but they occur after hospitalization or in 48 hours after discharge from ICU (3). Although the number of beds in ICU constitutes mostly 10% of all hospital beds, approximately 20–25% of all nosocomial infections are the infections acquired in ICU (4). The patients followed in ICU are those who have one or more organ failure as well as a life- threatening primary disease, use broad spectrum antibiotics, and can undergo all kinds of medical and surgical interventions and monitorization. Therefore, the patients in ICU are more susceptible to nosocomial infections, which can be an important cause of mortality and morbidity in ICU.

Standard precautions that are taken for the control of nosocomial infections include washing hands, wearing gloves, wearing a mask and apron, sterilizatin or disinfection of patient care instruments, measures for environmental control, collecting sharp objects, and appropriate placement of patients (6). In addition, while designing and planning the facilities in ICU where high-risk patients are hospitalized, adequate and safe water supply, air-conditioning suitable for the division and aim, proper hygiene, sufficient area for beds, distance between beds, handwashing facilities, isolation rooms, and appropriate conditions based on scientific foundations should be taken into consideration. The frequency of infections and spread of resistant microorganisms are seen at higher rates in ICU that is not structured under suitable conditions (7).

In this study, it was aimed to investigate the effect of reconstructed ICU on the rates of nosocomial infections acquired in ICU retrospectively and to evaluate this reconstruction.

Methods

After receiving ethical approval from the Non-Invasive Research Ethics Committee at Fırat University (dated April 08, 2014 and numbered 07-06), records and files of the patients who were hospitalized in the Department of Anaesthesia and Intensive Care at Fırat University between March 14, 2011 and March 14, 2013 were examined retrospectively.

The patients that were included in the study were put into two groups based on the reconstruction date (March 14, 2012) of ICU. They were grouped as those who were hospitalized in ICU in the year before March 14, 2012 (Group A) and those who were hospitalized in ICU in the year after March 14, 2012 (Group B). The diagnosis of nosocomial infection was established in accordance with modified CDC criteria as follows (8). Urinary system infection was diagnosed by considering clinical findings of infection and the growth (>10⁵/mL) of the same microorganism in successive two cultures in patients with urinary catheter. For other nosocomial infections, the presence of clinical findings and one positive microbiological culture were considered as nosocomial infection and colonisations were also determined. Collecting bacteriological cultures before the initiation of new antibiotics was our routine procedure.

The follow-up protocols of the patients were prepared for evaluating patients’ data on age, gender, Glasgow Coma Scale (GCS) at admission, primary reasons for hospitalization, frequency of infection, assessment of infection frequency according to age groups, factors causing infections, types of infections, the distribution of infection factors according to the types of infections, the distribution of infection types according to the diagnoses for hospitalization, duration of hospitalization in ICU, duration of mechanical ventilation, and discharge from ICU. Based on these recordings, the places where infection occurred in hospital and their frequencies were compared.

For reconstruction, the location of ICU was completely changed. In the old building of ICU, there was an entrance with barriers following a corridor that was located just after the main gate and the families of patients were used to be informed in a room at this corridor. On the other hand, in the new ICU, there is a sliding door following the main gate and corridor and the families of patients are mostly informed in an area designed for this aim. The differences between the old ICU and reconstructed ICU are presented in Table 1. With restructuring, the beds in ICU were placed in two units that were separated with a window wall for meeting the criteria stated in the “Notification for Procedures and Principles Regarding the Implementation of Intensive Care Services in Health Facilities Providing Inpatient Treatment”, which was published in the Official Gazette dated July 20, 2011.

Table 1.

Differences between old and new ICUs

	Old ICU	New ICU
Numbers of beds and ventilators	16 beds-14 ventilators	17 beds -17 ventilators
Distance between patient beds	Mean 1.5 m	Mean 2.0 m
Isolated rooms but only 2 are active.	Normal patient room, 3 rooms in different places filters and are entered through an automatic door	Rooms with window walls, which have specific hepa
Design of ICU	A single large saloon that is passively separated one has 9 beds and the other has 8 beds.	Two different saloons separated with window,
Entry of ICU	An entrance with barriers after an automatic door sliding door with a sensor.	An entry after the automatic door, with a different
Air-conditioning and hepa filter	2 saloon type air conditioners their exhausts- air-conditioning that can be automatically controlled	A total of 20 filters and Hepa filter system including
Number of nurses  Shifts: 3 nurses on average	12 nurses on average Shifts: 4 nurses on average	16 nurses on average
Nursing training	No regular training	Regular in-service trainings
Preparation of medication and storing	Available medications are prepared bedside	A separate section for storing and preparing medications
Number of available hand basins	4	7
Patient bathing	Each patient is given a bath in bed	There is a special section for giving a patient bath.
Toilets	A single common toilet where urines of patients are emptied.	Urines of patients are emptied into a separate place. Apart from that, there are two toilets.

ICU: intensive care unit

Statistical analysis

Descriptive statistics of the obtained data were presented as number, percentage, and mean ± standard deviation. Square test was used for determining categorical risk factors. Numerical data were analysed by using independent t-test for comparing two groups and by using variance analysis for comparing groups more than two. Statistical analyses were performed by using IBM Statistical Package for the Social Sciences version 21.0 (IBM SPSS Statistics; Armonk, NY, USA) software and the value of p<0.05 was accepted as the significance level.

Results

This study included patients who were older than 18 years, stayed in our ICU for longer than 48 hours, and had no infection according to the results of physical examination and culture and laboratory analyses performed at admission. Of totally 1101 patients, 695 patients were excluded from the study because of lack of data, age younger than 18 years, duration of hospitalization shorter than 48 hours, and the presence of infection at admission and 406 patients that met the inclusion criteria were included in the study (214 patients in Group A and 192 patients in Group B) (Figure 1).

Figure 1.

Distribution of patients according to the groups

While the mean age was found to be significantly lower in Group B (p<0.05), there was no significant difference between the groups in terms of gender and GCS at admission (p>0.05) (Table 2).

Table 2.

Mean values of patients’ ages, genders, and GCS according to the groups

	Group A	Group B
Age	60.94±18.919	55.61±20.502*
Gender
Male	122	124
Female	92	68
GCS	5.546±2.76041	5.322±2.87249

^*(p<0.05).

GCS: Glasgow Coma Scale

The primary reasons for hospitalization in ICU were frequently trauma, postoperative respiratory distress, and cerebrovascular disease in both groups, but there was no statistically significant difference (p>0.05) (Figure 2).

Figure 2.

Distribution of primary diagnoses for hospitalization in intensive care unit according to the groups

CVD: cerebrovascular disease; Intox: intoxication

In patients in Group B, the rates of infections were detected to be significantly lower (p=0.001) (Table 3). In the evaluation of the groups with regard to patients’ ages, no statistically significant difference was found for the frequency of infections (p=0.202).

Table 3.

Distribution of infection rate according to the groups

Infection		Group A	Group B	Total
Existent	n	88	48*	136
	%	41.1%	25.0%	33.5%
Non-existent	n	126	144	270
	%	58.9%	75.0%	66.5%
Total	n	214	192	406
	%	100.0%	100.0%	100.0%

^*p<0.05

The most common infectious agent was found to be Acinetobacter in both groups. When the groups were compared in terms of the frequencies of infectious agents, Acinetobacter, Pseudomonas, and Escherichia coli were detected to be at significantly lower rates in Group B (p=0.049, p=0.004, p=0.002) (Table 4).

Table 4.

Distribution of infectious agents according to the groups

	Group A		Group B
	Number	%	Number	%	p
Acinetobacter	39	18.2	23	12.0	0.049*
Pseudomonas	33	15.4	13	6.8	0.004*
Escherichia coli	19	8.9	4	2.1	0.002*
Klebsiella	11	5.1	7	3.6	0.314
Staphylococci	6	2.8	9	4.7	0.229
Enterococci	6	2.8	5	2.6	0.574

^*p<0.05

While the most common infection was found to be ventilator-associated pneumonia (VAP) in both groups, wound site infection was detected to be the least frequent. The rates of urinary system infection and VAP were significantly lower in Group B (p=0.019, p=0.000) (Table 5).

Table 5.

Distribution of infection types according to the groups

		Group A	Group B
VAP	Number	70	28*	0.000
	%	32.7	14.6
Urinary infection	Number	40	20*	0.019
	%	18.7	10.4
Catheter-associated infection	Number	26	21	0.703
	%	12.1	10.9
Wound site infection	Number	10	9	0.994
	%	4.7	4.7

^*p<0.05

The most common VAP agents were observed to be firstly Acinetobacter and then Pseudomonas. For urinary system infection, Pseudomonas was the most common agent. It was followed by Acinetobacter and Escherichia. Acinetobacter was determined to be the most frequent agent for catheter-associated infection and wound site infection. In our ICU, Acinetobacter for VAP was found to be at a significantly higher rate compared to other infectious agents (p<0.05) (Figure 3).

Figure 3.

Distribution of infectious agents according to infection types

VAP: ventilator-associated pneumonia. *p<0.05

There was no statistically significant difference between the primary diagnoses of the patients for hospitalization in ICU and the frequencies of infection types (p>0.05) (Table 6).

Table 6.

Distribution of infection types according to primary diagnosis for hospitalization

	Urinary infection		VAP		Catheter-associated infection		Wound site infection
Diagnosis for hospitalization	A	B	A	B	A	B	A	B
Trauma	5	5	19	7	7	6	1	4
Cardiopulmonary Arrest	4	1	7	4	2	4	1	0
CVD	10	8	14	5	5	3	3	0
Postop respiratory distress	6	3	9	10	4	4	1	3
Intoxication	0	1	0	0	1	1	0	0
Cardiac failure	2	1	4	0	2	1	1	0
Respiratory failure	8	1	11	1	3	1	0	2
Renal failure	1	1	3	0	1	0	0	0
Other reasons	3	0	3	1	2	1	3	0
Total	40	20	70	28	26	21	10	9

CVD: cerebrovascular disease

With regard to the mean duration of hospitalization in ICU, no statistically significant difference was found between Group A (16.96±17.484 days) and Group B (16.63±19.092 days) (p=0.43). The mean length of mechanical ventilation was significantly shorter in Group B (12.22±17.595 days) than in Group A (15.01±16.681 days) (p=0.001).

The number of patients discharged with recovery was statistically significantly higher in Group B and the number of exitus patients was significantly lower in Group B (p<0.05) (Figure 4).

Figure 4.

Patients’ discharge state

*p<0.05

Discussion

The number of studies on the frequencies of infections in ICU has been increasing in recent years. While many of them have been published in USA, studies are more restricted in other countries. In most of these studies, the importance of comparing data about qualified care services in ICUs and prevention of infections is emphasized (9). Therefore, in this study, it was aimed to investigate the effect of reconstructed ICU on the rates of nosocomial infections acquired in ICU and changes in infection rates retrospectively.

The rates of infections in ICU are high because of using invasive tools, prolonged hospitalization, variety of underlying diseases, and characteristics of intensive care (1). Infection criteria can be different among various studies. We used modified CDC criteria (8). Time interval between admission to ICU and the development of a nosocomial infection can vary between 0 and 72 hours (10). In our study, 48-hour interval, which is commonly used, was preferred. The rates of infections were evaluated in 406 of 1101 patients, who met the criteria, in two-year study period. While infection rate was 41.1% in the old ICU, it was found to be 25% in the newly reconstructed ICU. Infection rate was high in the old ICU, but the rate in the restructured unit was consistent with rates in literature (11, 12).

Despite studies showing that age is not a risk factor for infection in ICUs (13, 14), there are also some other studies reporting that age above 60 years is a risk factor for ICU infections (15, 16). In the literature, no relationship has been reported between primary diagnoses for hospitalization in ICU and the frequencies of infection types (13). Similarly, in our study, there was no relationship between age and primary diagnoses for hospitalization and the rates of infections.

In many studies, it has been reported that there is a positive correlation between the duration of hospitalization in ICU and all infection rates and this increases mortality as well as the rates of infections (13, 15, 17, 18). Nosocomial infection increases the length of hospitalization in ICU by 1–4 days for urinary system infection and 7–30 days for pneumonia (17). In our study, the durations of hospitalization and ventilation were found to be shorter in our reconstructed ICU and concordantly, mortality was detected to be lower.

Types and rates of ICU infections vary among different studies. Pneumonia, urinary system infections, and bloodstream infections constitute approximately 68–77% of all nosocomial infections (19, 20). In a multicentre study, pneumonia (39.7%), urinary system infections (20,5%), and wound site infection (13.3%) were reported to be the most common nosocomial infections in ICUs (20). In another study, the most frequent ICU infections were found to be wound site infection (34%), pneumonia (26%), bloodstream infections (17%), and urinary system infections (10%) (13). In a study conducted on 1417 intensive care patients from 17 countries in the Western Europe, pneumonia (46.9%), lower respiratory tract infection (17.8%), urinary system infections (17.6%), and bloodstream infections (12%) were reported as the most frequently seen nosocomial infections (21). In our study, these frequent diseases were detected to be pneumonia (32.7%/14.6%), urinary system infection (18.7%/10.4%), catheter-associated infection (12.1%/10.9%), and wound site infection (4.7%/4.7%) in Group A and Group B, respectively.

Like the rates and types of infections, isolated microorganisms can vary among ICUs. While Enterobacteriaceae (25.9%), Pseudomonas aeruginosa (17.2%), Staphylococcus aureus (10.9%), and MR-CNS (methicillin resistant coagulase-negative staphylococci) (4.1%) are reported to be the most common isolated infectious agents in a study (20), Enterobacteriaceae (34.4%), Staphylococcus aureus (30.1%), Pseudomonas aeruginosa (28.7%), MR-CNS (19.1%), and their fungi (17.1%) are shown to be more frequent in another study (21). Acinetobacter, Pseudomonas, E. coli, Klebsiella, Staphylococci, and Enterococcus were found to be the most common isolated microorganisms in both groups in our study (Table 4).

In some studies, Staphylococcus aureus (17%), Pseudomonas aeruginosa (15.6%), and Enterobacteriaceae (10.9%) were reported to be the most isolated microorganisms for pneumonia (19). On the other hand, in other studies, Pseudomonas aeruginosa, Staphylococcus aureus and Acinetobacter spp. were shown to be the most isolated pathogens in ICU (22, 23). Acinetobacter and Pseudomonas were detected to be the causes of pneumonia in our ICU, which is consistent with other studies in literature.

In our study, Acinetobacter was found to be the most common infectious agent for wound site infection and Pseudomonas, Acinetobacter and Escherichia coli were found to be the most common isolated urinary system microorganisms. These findings were consistent with the literature (19, 24, 25).

There are some studies reporting that trauma, mechanical ventilation, and cerebrovascular disease increases the risk for infection in ICU (13, 20). Coma, trauma, and mechanical ventilation due to respiratory failure were found to be independent risk factors for infection in our ICU.

The number of staff working at ICU and patient/nurse ratio play an important role in the control of infection. For the patient/nurse ratios of 1.2, 1.5, and 2, the odds ratios for infection were found to be 3.95, 16.6, and 61.5, respectively (26). While total number of nurses was 12 in our old ICU, it was increased to 16 in our reconstructed ICU and the mean number of nurses on call elevated with this change. Considering that the rate of infection is associated with patient/nurse ratio, a significant decrease of infection rates in Group B even with this small change suggests that more intensive care nurses are needed to reach the targeted infection rates.

The crux of the problem for nosocomial infections is the inability to provide healthy conditions in the ICUs of many hospitals. Examples of these unhealthy conditions include poor architectural structures, insufficient isolation conditions, problems related to air-conditioning, medical waste and biological hazardous waste in patient rooms of ICU, dirty treatment and common fields, and faecal residue in ICU patient toilets. Others are leakages on walls and contaminated cupboards, damaged floor coverings, trash and holes that generate dirt on the floor, and foreign bodies on window ledges. In addition, some of ICU staff are not aware of that invasive interventions such as the establishment of vascular access cause infections to spread and they do not have knowledge about how to decrease the rates of these infections (27).

For the prevention of infection due to particles smaller than 5 μm, which are exposed through inhalation, the environment should be ventilated by using a special ventilation system. In such a case, negative pressure and 6–12 air changes per hour should be provided in a single room. Particles larger than 5μm do not stay suspended in the air and they cannot travel the distances farther than one meter. Because droplets do not spread and stay suspended in the air, ventilation of the environment with special ventilation systems is ineffective for preventing infection. In such situations, droplet isolation should be applied in addition to standard precautions (28).

Conclusion

Restructuring comes with a lot of changes and leads to decreased infection rates. However, considering that many parameters can cause this decrease, it is difficult to determine which change is the major factor. Particularly the staff working in ICU can be a source of these infections. Therefore, it is important to provide continuing training and efficient surveillance practices for decreasing infections. Physical conditions of our ICU was improved (location, air-conditioning, hepa filter ventilation). In addition to trainings given in intensive care, more comprehensive studies are needed in order to determine the roles of other factors in preventing infections.