Pediatric Respirology and Critical Care Medicine

: 2017  |  Volume : 1  |  Issue : 4  |  Page : 77--80

Comparison of ventilator-associated pneumonia in children using disposable and nondisposable ventilator circuits

Panida Srisan1, Kallayanee Meechaijaroenying2,  
1 Department of Pediatrics, Division of Pulmonology and Critical Care, Queen Sirikit National Institute of Child Health, College of Medicine, Rangsit University, Bangkok, Thailand
2 Department of Pediatrics, Paolo Memorial Hospital, Bangkok, Thailand

Correspondence Address:
Panida Srisan
Department of Pediatrics, Division of Pulmonology and Critical Care, Queen Sirikit National Institute of Child Health, College of Medicine, Rangsit University, 420/8 Rajavithi Road, Rajathevi, Bangkok 10400


Aims: The aim of the study was to compare the incidence of ventilator-associated pneumonia (VAP), mortality, and ventilator circuit-related cost associated with patients using disposable ventilator circuit to those associated with patients using nondisposable ventilator circuit. Setting and Design: A prospective randomized controlled study in a 10-bed Pediatric Intensive Care Unit at Queen Sirikit National Institute of Child Health between November 2011 and October 2012. Subjects and Methods: Children aged 1 month to 18 years who were ventilated >48 h were enrolled. Patients were randomized to be ventilated with a disposable or nondisposable heated wire ventilator circuit. Statistical Analysis Used: Statistical analysis was performed using SPSS version 17.0. The P < 0.05 was considered statistically significant. Results: Ninety-eight patients were enrolled. Of these, 48 were administered the disposable ventilator circuit, whereas 50 were administered the nondisposable ventilator circuit. The VAP rate was 20.53/1000 ventilator days for the former (n = 7) compared to 30.77/1000 ventilator days (n = 12) for the latter (odds ratio: 1.85; 95% confidence interval: 0.66–5.19, P = 0.24). The mortality rates were 2.1% in the disposable and 12% in the nondisposable circuit groups (P = 0.06). The unit cost of the disposable circuit (US dollar [USD] 51.60) was higher than that of the nondisposable circuit (USD 37.90). However, the total cost for the nondisposable group was higher due to the required use of more units (63 circuits for the disposable group vs. 95 circuits for the nondisposable group). Conclusions: The type of ventilator circuit is not likely to affect the VAP rate and mortality in children. The unit cost of a disposable circuit is higher than that of a nondisposable circuit. The total cost depends on the number of circuits used in each patient.

How to cite this article:
Srisan P, Meechaijaroenying K. Comparison of ventilator-associated pneumonia in children using disposable and nondisposable ventilator circuits.Pediatr Respirol Crit Care Med 2017;1:77-80

How to cite this URL:
Srisan P, Meechaijaroenying K. Comparison of ventilator-associated pneumonia in children using disposable and nondisposable ventilator circuits. Pediatr Respirol Crit Care Med [serial online] 2017 [cited 2023 Mar 22 ];1:77-80
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Full Text


Ventilator-associated pneumonia (VAP), the most important hospital-associated infection (HAI) in the Intensive Care Unit (ICU), is defined as pneumonia that occurs in a patient who is mechanically ventilated for at least 48 h.[1],[2],[3],[4],[5] It is associated with increased mortality, morbidity, length of stay, and health-related costs. The presence of an endotracheal tube (ETT) is the most important risk factor of VAP. Additional risk factors in children are underlying respiratory disease, longer duration of mechanical ventilation, genetic syndromes, immunodeficiency, continuous enteral feeding, the use of H2 antagonist, the use of narcotics or neuromuscular blocking agents, previous antibiotic exposure, gastroesophageal reflux, younger age, reintubation, and supine positions.[2],[3],[4]

The prevention of VAP is essential in all ventilated patients.[1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13] Several strategies with the aim of preventing microaspiration, the colonization of the respiratory or the gastrointestinal tract by pathogenic organisms, or the contamination of ventilator equipment have been proven to be effective in adults and children. The possibility of cross infections from improperly cleaned nondisposable ventilator circuits and humidifiers was previously documented.[10],[12],[14],[15] The use of disposable ventilator-related equipment is a standard practice in many developed countries because it involves a lower chance of infection and is more convenient to use. In contrast, the use of nondisposable ventilator circuits is more common in developing countries, including Thailand, due to their lower costs.[14] There have been no previous studies comparing the incidence of VAP across different types of ventilator circuits. Therefore, this study was conducted to compare the incidence of VAP in children administered a disposable ventilator circuit to that in children administered a nondisposable ventilator circuit. The ventilator circuit-related costs and mortality of both groups were also compared.

 Subjects and Methods

This research was a prospective randomized controlled study in the 10-bed-multidisciplinary pediatric ICU (PICU) of the Queen Sirikit National Institute of Child Health. The study was approved by the Institutional Review Board.

All the pediatric patients aged 1 month to 18 years who were intubated and mechanically ventilated for at least 48 h between November 2011 and October 2012 were enrolled. The exclusion criteria were ventilation for >48 h before admission to the PICU, postelective surgery, prior palliative care, and refusal of consent of a parent or a guardian.

The patients were randomly allocated to be ventilation with a disposable or a nondisposable ventilator circuit. The disposable circuit in this study was a dual heated wire breathing circuit (Evaqua TM 1, Fisher and Paykel Healthcare Ltd., Auckland, New Zealand). The nondisposable heated wire circuit came equipped with the ventilator having been sold to the hospital. The frequency of a ventilator circuit change was every 7 days for the former (Evaqua TM 1 user instruction) and every 5 days for the latter (our hospital policy). The disinfection process for the nondisposable circuit included wash with soap and clean water, chemical disinfection with sodium dichloroisocyanurate (Mediklean ™), hot-air drying, and ethylene oxide gas sterilization, which was approximately 7 h.

The data collected included age, sex, weight, underlying disease, the pediatric risk of mortality (PRISM) III score, the risk factors of VAP, the duration of mechanical ventilation (number of ventilator days), the length of PICU stay, and mortality. VAP was diagnosed using the Centers for Disease Control and Prevention definition of nosocomial pneumonia.[16] That is, the incidence of VAP refers to the number of VAP cases per 1000 ventilator days. Ventilator utilization was expressed as a ratio of ventilator days to a PICU stay. The semi-quantitative culture of blood, sputum, or tracheal aspirate was used in this study.

The total ventilator circuit-related cost is the sum of material, labor, and maintenance costs. The labor cost is the total wage incurred on preparing, providing, and disinfection a ventilator circuit. The maintenance cost is calculated from the equipment and the depreciation cost of the disinfection process. All the costs were calculated in Thai Baht together with its equivalent in US dollars (USDs).

The sample size was calculated based on the VAP rate of 26.0/1000 ventilator days in nondisposable circuits (our previous VAP incidence) at the estimated VAP rate reduction of 30%. The result was 49 cases in each group.

All descriptive data were expressed as mean ± standard deviation or number (percentage). Categorical variables were analyzed using the Chi-square or the Fisher's exact test. The unpaired t-test or the Mann–Whitney U-test was used to compare continuous variables. The P < 0.05 was considered statistically significant. Statistical analyses were performed using the SPSS Statistical software version 17.0 (SPSS: International Business Machines Corp., New York, USA) (


Ninety-eight patients were enrolled. Of these, 50 (51%) were in the nondisposable circuit group, while 48 (49%) were in the disposable circuit group. The patient demographic data, the PRISM III scores, and the underlying diseases were not significantly different between the two groups. The most common underlying diseases in the disposable and the nondisposable circuit groups were cardiovascular diseases and genetic syndromes, respectively. The risk factors of VAP, including previous antibiotic exposure, retained nasogastric or orogastric tube, the use of H2 antagonist, sedation, open suction system, and reintubation, were not significantly different between the two groups [Table 1]. The most common cause of intubation was pneumonia with acute respiratory failure.{Table 1}

From the results, VAP occurred in 19 patients, 7 in the disposable circuit group and 12 in the nondisposable circuit group. The total VAP rate was 26.0/1000 ventilator days. The VAP rate was 14.6% and 20.53/1000 ventilator days in the disposable circuit group compared to 24% and 30.77/1000 ventilator days in the nondisposable circuit group (odds ratio [OR]: 1.85; 95% confidence interval [CI]: 0.66–5.19, P = 0.24). There were no significant differences in ventilator days, PICU stays, and ventilator utilization between the two groups [Table 2]. The organisms isolated from the tracheal aspirates were Acinetobacter baumannii (50%), Pseudomonas aeruginosa (40%), and Klebsiella pneumoniae (10%).{Table 2}

Of all the cases, there were 7 deaths, 1 in the disposable circuit group (only in the non-VAP group) and 6 in the nondisposable circuit group (3 in the non-VAP group and 3 in the VAP group). The mortality rate in the disposable circuit group (2.1%) was not significantly different from that in the nondisposable circuit group (12%) (OR: 0.16; 95% CI: 0.02–1.35, P = 0.06). Such deaths were caused mainly by severe sepsis (5/7), followed by pulmonary hemorrhage (1/7) and chronic lung disease (1/7). The OR for VAP death in the nondisposable circuit group was 3.9 [Table 2].

In terms of costs, the unit cost of a ventilator circuit was USD 51.60 for the disposable circuit compared to USD 37.90 for the nondisposable circuit. Nevertheless, due to its use of more circuits, the nondisposable circuit incurred a higher total cost of USD 3600 (95 circuits) compared to USD 3250 for the disposable circuit (63 circuits) [Table 3].{Table 3}


VAP has been reported to occur in approximately 20% of all HAIs in PICU, with the range of 1–63/1000 ventilator days.[2],[3] The incidence of VAP in this study (26.0/1000 ventilator days) was similar to that in our previous study in 2008 (26.0/1000 ventilator days) (unpublished data). In contrast, VAP rates in children have varied greatly depending on surveillance definitions, PICU settings, and national income levels.[1],[2],[3],[10],[16],[17],[18] Several studies from Asia, including Thailand, reported VAP rates between 8 and 70/1000 ventilator days with the mortality between 5% and 23%.[3],[18],[19] The pathogenesis of VAP involves the complex interactions between the presence of ETT, VAP risk factors, the virulence of bacteria, and host immunity. Pathogenic organisms can originate from either endogenous or exogenous sources. The aspiration of contaminated oropharyngeal secretion into the lower airway is a prerequisite for VAP development. The colonization of ETT, ventilator circuit, humidifier, nebulizer, or other respiratory equipment can also lead to lower airway contamination. VAP is rarely caused by hematogenous spread.[1],[5],[6],[10],[11],[12],[13],[14],[15] The most common causative organisms are Gram-negative pathogens such as P. aeruginosa, A. baumannii, and Enterobacteriaceae with increasing reports of multidrug-resistant strains in Asia.[3],[5],[15],[18],[19]

Recommendations for VAP prevention in children and adults include hand hygiene, head of bed elevation, oropharyngeal cleansing, sterilization or disinfection of respiratory equipment, no routine change of ventilator circuit, daily sedation interruption and assessment of readiness for weaning, active surveillance of VAP, and education of health-care staff.[1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13],[14] Multiple VAP preventive strategies are already implemented in our PICU, which may explain the comparable VAP rates between disposable and nondisposable circuits in this study.

From the findings, the main cost of a disposable circuit is material cost, whereas the costs of a nondisposable circuit predominantly involve both material and labor ones. In our hospital, the nondisposable circuit is usually used until it is broken (2–3 years). Despite its high cost, disposable circuits are increasing popular due to their elimination of cross infections and ease of use. However, a number of other factors need to be taken into consideration, especially labor availability, wage rates, and circuit change intervals. Labor shortage is currently an important issue worldwide, including in developing countries. A rise in wage rates will increase the labor and the unit costs of nondisposable circuits. Besides, if the circuit change interval can be extended, the number and costs of ventilator circuits will be decreased. Clinical practice guidelines recommend that ventilator circuits should not be changed routinely for infection control purposes. Although the maximum duration that circuits can be used safely is unknown, previous studies demonstrated that the extension of a ventilator circuit change interval for children from 3 to 7 days did not increase VAP rates and was cost-effective.[1],[6],[11],[12],[18] The reason for the difference in the number of circuits was the use of a high-frequency oscillator required for some patients in the nondisposable circuit group.

There was a trend toward mortality in the nondisposable group (12%), compared to the disposable group (2.1%) (P = 0.06). In the nondisposable circuit group, VAP death was 25% (3/12) and non-VAP death was 7.9% (3/38), with the OR of 3.9. If the number of patients was increased, the significant difference in mortality between disposable and nondisposable circuit groups might be demonstrated, included the difference between VAP and non-VAP death in the disposable circuit group.

VAP-related cost was not considered in this study as there was no difference in VAP rates between both groups. Nevertheless, VAP caused by multidrug-resistant bacteria is an emerging global problem, resulting in higher mortality and healthcare-related costs.[3],[20]


Our study suggests that the VAP rates between children using disposable and nondisposable ventilator circuits are not different. In addition, the ventilator circuit-related costs of disposable circuits are likely to be high.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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