Risk Factors for Ventilator-Associated Pneumonia in Infants and Children: a Cross-sectional Cohort Study Denise Miyuki Kusahara, Camila da Cruz Enz, Ariane Ferreira Machado Avelar, Maria Angélica Sorgini Peterlini and Mavilde da Luz Gonçalves Pedreira Am J Crit Care 2014;23:469-476 doi: 10.4037/ajcc2014127 © 2014 American Association of Critical-Care Nurses Published online http://www.ajcconline.org Personal use only. For copyright permission information: http://ajcc.aacnjournals.org/cgi/external_ref?link_type=PERMISSIONDIRECT
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P ulmonary Critical Care
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FACTORS FOR VENTILATOR-ASSOCIATED PNEUMONIA IN INFANTS AND CHILDREN: A CROSSSECTIONAL COHORT STUDY ISK
By Denise Miyuki Kusahara, RN, PhD, CCRN, Camila da Cruz Enz, RN, Ariane Ferreira Machado Avelar, RN, PhD, Maria Angélica Sorgini Peterlini, RN, PhD, and Mavilde da Luz Gonçalves Pedreira, RN, PhD, CCRN
©2014 American Association of Critical-Care Nurses doi: http://dx.doi.org/10.4037/ajcc2014127
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Background The epidemiology of ventilator-associated pneumonia is well described for adults, but little information is available on risk factors for this disease in children. Objective To identify predisposing factors for ventilatorassociated pneumonia in children. Methods A cross-sectional prospective cohort study of 96 patients in a 9-bed pediatric intensive care unit was performed. Variables examined were demographic characteristics, inpatient care, medications, nutrition, invasive procedures, and characteristics of mechanical ventilation. Data were analyzed by using Pearson χ2 analysis, Fisher exact and Mann-Whitney tests, odds ratios, and forward stepwise logistic regression. Results Occurrence of ventilator-associated pneumonia correlated positively with use of nasoenteral tubes (odds ratio, 5.278; P < .001), intermittent administration of nutritional formula (odds ratio, 6.632; P = .005), emergency reintubation (odds ratio, 2.700; P = .02), use of vasoactive drugs (odds ratio, 5.108; P = .009), duration of mechanical ventilation (P < .001), and length of stay in the pediatric intensive care unit (P < .001) and in the hospital (P = .01). Conclusion Use of vasoactive drugs, presence of a nasoenteral tube, and duration of stay in the pediatric intensive care unit were independent risk factors for ventilator-associated pneumonia. (American Journal of Critical Care. 2014;23:469-476)
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V
entilator-associated pneumonia (VAP) is defined as inflammation of the pulmonary parenchyma due to the action of an infectious agent. VAP occurs up to 48 hours after the initiation of mechanical ventilation in patients who had tracheal intubation and did not have pneumonia at the time of intervention.1 Health care– associated infections occur in approximately 12% of patients in the pediatric intensive care unit (PICU), and pneumonia is the second most common type of nosocomial infection, accounting for 22.7% of the infections in the PICU. VAP occurs in 9% to 27% of intubated patients, and the risk for VAP increases 1% to 3% for each day of mechanical ventilation. The mortality rate for patients with VAP is high, from 33% to 71%.1,2
The pathogens that cause VAP are able to overcome the mechanical, hormonal, and/or cellular defenses of the body, thereby invading, colonizing, and establishing an infection within the lower part of the respiratory tract. Microbial access to the otherwise sterile lower part of the respiratory tract can occur via 4 mechanisms: aspiration of pathogencontaining oropharyngeal secretions from the gastric cavity or sinuses, dissemination of organisms from a contiguous area such as the pleura, inhalation of contaminated aerosols after the use of respiratory therapy devices, and hematogenous spread from remote infection sites to the lung.3,4 The epidemiology and prognosis of VAP are well described in adults; however, little information is available for VAP in infants and children, especially attributed risk factors and outcomes such as morbidity, mortality, and cost. The information available comes primarily from studies conducted in developed countries. Although the incidence of VAP has decreased significantly in developed countries since the 1990s as a result of improved clinical knowledge and the successful implementation of preventive strategies,
Data were collected in a pediatric intensive care unit at São Paulo Hospital in Brazil.
About the Authors Denise Miyuki Kusahara is a pediatric critical care nurse, Ariane Ferreira Machado Avelar is an adjunct professor, Maria Angélica Sorgini Peterlini and Mavilde da Luz Gonçalves Pedreira are associate professors, Pediatric Nursing Department, and Camila da Cruz Enz is a registered nurse and a former scientific initiation fellow, Escola Paulista de Enfermagem, Universidade Federal de São Paulo, São Paulo, Brazil. Corresponding author: Denise Miyuki Kusahara, RN, PhD, Nursing School, Escola Paulista de Enfermagem, Universidade Federal de São Paulo, Rua Napoleão de Barros, 754, Office 113, São Paulo, Brazil CEP 04024002 (e-mail: [email protected]).
CCRN,
470
the incidence still remains high.5 Thus, additional studies are needed to determine the risk factors for VAP in PICU patients. The results from these studies would contribute to improving the standard of care for children undergoing mechanical ventilation. In this context, the primary objective of this study was to identify risk factors for the development of VAP related either to the patient or to the care given in the PICU.
Methods The study was a cross-sectional prospective cohort investigation. The study is part of a randomized clinical trial to test the effectiveness of oral care with 0.12% chlorhexidine in decreasing VAP in critically ill children. In the clinical trial, use of 0.12% chlorhexidine did not significantly modify the incidence of VAP in a sample of children.6 Site and Study Sample The data were collected in a 9-bed PICU at São Paulo Hospital, a 700-bed tertiary care nonprofit hospital affiliated with the Federal University of São Paulo, São Paulo, Brazil. All the patients and/or their legal representatives who consented to participate in a prospective, randomized controlled trial study (Clinical Trials Identifier: NCT01083407) were recruited for the study. Children were included in the sample if they were expected to remain intubated and treated with mechanical ventilation for more than 24 hours. Patients were excluded if they were newborns, had a tracheostomy, had a diagnosis of pneumonia on admission to the PICU, had been intubated longer than 24 hours before admission to the PICU, or declined consent. The sample comprised 96 children who fulfilled inclusion criteria. The data were prospectively collected from June 2005 to June 2008 onto a standardized form. At the time of data collection, the VAP prevention protocol in the PICU included
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Table 1 Agreement between the Centers for Disease Control and Prevention/National Healthcare Safety Network (CDC/NHSN) criteria and the Clinical Pulmonary Infection Score (CPIS) for diagnosis of ventilator-associated pneumonia (VAP)
elevation of the head of the bed 30º, interventions to prevent peptic ulcer disease, and standardized oral care. Site-specific algorithms for clinically or bacteriologically defined pneumonia, including serial chest radiographs, signs and symptoms, and laboratory findings were followed. Study Variables The outcome variable was defined as the occurrence of VAP. Development of VAP was quantified by using the Clinical Pulmonary Infection Score (CPIS) and confirmed by using the alternative pneumonia clinical criteria for infants and children defined by the Centers for Disease Control and Prevention and the National Healthcare Safety Network (CDC/NHSN). The CPIS is a clinical score of 0 to 12 based on the following 6 variables: temperature, blood leukocyte count, tracheal secretions, radiological pulmonary imaging, oxygenation, and microbiological data. Scores of 6 or greater are considered indicative of VAP.7 The CDC/NHSN diagnosis is based on serial chest radiographs, changes in body temperature, blood leukocyte count, oxygenation, lung auscultation, and characteristics of the pulmonary secretions.8 A physician determined these scores. When the CPIS and the CDC/NHSN scores did not agree, a second expert analyzed the data to determine the final diagnosis. Each episode of VAP was characterized as early or late onset. Early-onset VAP occurs during the first 4 days of mechanical ventilation and late-onset VAP develops 5 or more days after initiation of mechanical ventilation.1 Variables examined were intrinsic and extrinsic risk factors as described in the literature and included demographic characteristics, PICU hospitalization, drugs used, nutritional and intensive therapies, invasive procedures, pulmonary mechanical ventilation, and intubation characteristics. Statistical Analysis Categorical variables were analyzed by using both absolute and relative frequencies; continuous variables were analyzed on the basis of the median. Pearson χ2 and Fisher exact tests were used to compare the categorical variables. Numerical variables were analyzed by using the nonparametric MannWhitney test. The odds ratio with a 95% CI were calculated for the variables associated with a risk for VAP; these variables were identified as those with P ≤ .05 in the univariate analysis. These same variables were selected for inclusion in a stepwise forward logistic regression model. Variables that were not significant (ie, P > .05) when analyzed jointly were not included in the final analysis.
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VAP according to CDC/NHSNa VAP according to CPIS Absent Present a
Absent
Present
64 (67) 1(1)
4 (4) 27 (28)
Values in second and third column are number (%) of cases. κ = 0.878, P < .001.
Results Among the 96 children in the sample, VAP developed in 31 (32%), with an incidence of 16.4 episodes per 1000 days of mechanical ventilation. A strong agreement existed between the CDC/NHSN criteria and CPIS for the VAP diagnoses (κ statistic, 0.878; P < .001). The concordance was present in 91 analyses (95%; Table 1). Early-onset VAP was identified in 19 of the 31 children (61%) and late-onset VAP in 12 (39%). The mean CPIS scores were 3.8 (SD, 0.70) for the 68 VAP-free patients and 6.2 (SD, 0.70) for the 31 patients who had VAP. Mean total leukocyte count was significantly higher (P = .005) in children with VAP (17 000/μL; SD, 9644/μL) than in VAP-free children (10 796/μL; SD, 5238/μL). The primary causative bacterial species detected in samples of oropharyngeal and tracheal secretions were Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Enterobacter sp, Escherichia coli, and Staphylococcus aureus. No instances of VAP caused by fungi were identified in this sample of children. The median age of all patients was 28 months (range, 1-201 months), and most of the children were boys (64%). At the time of admission to the PICU, the median of the Nine Equivalents of Nursing Manpower Use Score was 31.5. The children were admitted to the PICU mainly after cardiac surgery (25%); gastrointestinal surgery (17%); trauma, brain injury, or neurological problems (17%), renal conditions (16%), respiratory diseases (9%), hematological disorders (10%), and endocrinologic disorders (6%). Of the 96 children, 34 (35%) had an enteral feeding tube, and 58 (60%) had a nasogastric tube (55% for feeding and 45% for gastric decompression). All 96 children had the head of the bed elevated at least 30º and had no clinical evidence of aspiration during the study period. Only 30 of the 96 children (31%) had a cuffed tracheal tube. The distribution frequencies and univariate analysis of the demographic characteristics upon admission to the PICU; drug, nutritional, and intensive therapies; invasive procedures; duration of mechanical ventilation; and endotracheal intubation for the 2 groups are given in Table 2.
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Table 2 Frequency distribution and univariate analysis of children with and without ventilator-associated pneumonia (VAP) No. (%) of patients Without VAP (n = 65)
Variable Age, months Mean (SD) Median Minimum-maximum
With VAP (n = 31)
Odds ratio
95% CI
P .07a
57.0 (58.2) 30.0 1-192
35.0 (48.1) 12.5 1-165
Male sex
44 (68)
17 (55)
Nutritional conditional Malnutrition Normal
31 (48) 34 (52)
17 (55) 14 (45)
Hospitalization within preceding 30 days
16 (25)
7 (23)
.74b
6 (9)
3 (10)
>.99c
Chronic disease
33 (51)
17 (55)
.88b
Emergency admission to pediatric intensive care unit
42 (65)
13 (42)
.06b
Diagnosis on admission Medical Surgical Infectious
45 (69) 39 (60) 24 (37)
21 (68) 18 (58) 16 (52)
.64b .66b .11b
Injured gums and oral mucosa
4 (6)
5 (16)
.15c
Abnormal, decayed, missing, and filled teeth index
9 (14)
3 (10)
.74c
Oral care with chlorhexidine digluconate 0.12%
31 (48)
15 (48)
.95b
Invasive procedures Central venous catheterization Transcardiac catheterization Arterial catheterization Intracranial monitoring Thoracentesis Bronchoscopy Thoracic drainage Hemodialysis
55 (85) 11 (17) 30 (46) 11 (17) 4 (6) 3 (5) 18 (28) 7 (11)
26 (84) 7 (23) 10 (32) 2 (6) 0 (0) 1 (3) 8 (26) 1 (3)
Tracheal intubation Orotracheal intubation Emergency reintubation Elective reintubation Uncuffed tracheal tube
65 (100) 11 (17) 10 (15) 42 (65)
31 (100) 11 (35) 07 (23) 24 (77)
Mechanical ventilation, h Mean (SD) Median Minimum-maximum
134.0 (84.3) 120 14-40
349.5 (277.0) 264 15-35
.001a
Transportation
36 (55)
18 (58)
.34b
Nutritional therapy Postpyloric tube Nasogastric tube To prevent gastric distention To provide nutritional support Continuous administration of diet Intermittent administration of diet
15 41 18 23 1 38
(23) (63) (44) (56) (2) (58)
19 (61) 17 (55) 8 (47) 9 (52) 1 (3) 28 (90)
Drug and intravenous therapy Antibiotic Sedative Analgesic Neuromuscular blocker Immunosuppressant Corticosteroids Antacids Vasoactive drugs Hemoderivatives
65 (100) 56 (86) 61 (94) 4 (6) 2 (3) 26 (40) 58 (89) 37 (57) 39 (60)
31 (100) 31 (100) 30 (97) 5 (16) 2 (6) 17 (55) 28 (90) 27 (87) 23 (74)
Previous pulmonary disease
.29b .66b
>.99b .27b .31b .40c .55c .99c .87b .42c
2.700
1.012-7.200
5.278
2.093-13.310
6.632
1.827-24.070
5.108
1.602-16.286
>.99b .02b .20b .40b
.001b .30b .82b >.99c .005b .33b .26b >.99b .16c .60c .17b .73b .009b .29b Continued
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Table 2 Continued No. (%) of patients Without VAP (n = 65)
Variable Mortality
c
P
95% CI
.07c
17 (26)
3 (10)
7.55 (4.6) 7 1-21
24.5 (26.5) 17 4-150 .01a
Length of hospitalization Mean (SD) Median Minimum-maximum
b
Odds ratio
.001a
Length of stay in pediatric intensive care unit Mean (SD) Median Minimum-maximum
a
With VAP (n = 31)
24.1 (23.3) 16.5 3-132
59.3 (70.4) 35 2-380
Nonparametric Mann-Whitney test. χ2 test. Fisher exact test.
Children with VAP tended to be younger than those without VAP, but the difference was not statistically significant (P = .07). Children with VAP did not differ significantly from children without VAP for the variables related to baseline characteristics and hospitalization. The 2 groups also did not differ significantly for nutritional status (according to the z score), previous hospitalization, previous pulmonary or chronic disease, and the type of diagnosis at admission. Similarly, the 2 groups did not differ significantly in use of invasive procedures (eg, central or peripheral venous catheterization, thoracic drainage, bronchoscopy, hemodialysis). Moreover, no significant difference was detected between the groups for intrahospital transfers; slightly more than half of the children with VAP required transportation during their stay in the PICU. In contrast, the 2 groups differed significantly for factors related to intensive treatment. Compared with children without VAP, a higher percentage of children with VAP received vasoactive drugs (P = .009), required an emergency reintubation (P = .02), or were fed via a postpyloric tube (P < .001) with intermittent administration of nutritional formula (P = .005). Compared with children without VAP, children with VAP had significantly greater duration of mechanical ventilation (P < .001) and significantly longer stays in both the PICU (P < .001) and the hospital (P = .01). Independent variables associated with the outcome variable were further analyzed to determine the odds ratio (Table 2). Use of vasoactive drugs, use of postpyloric tubes for nutritional therapy, and intermittent
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Table 3 Logistic regression model for the development of ventilator-associated pneumonia among critically ill children Coefficient
P
Odds ratio
Lower limit
Upper limit
Use of postpyloric feeding tube
1.19
.04
3.29
1.05
10.28
Use of vasoactive drugs
1.26
.05
3.52
1.01
12.25
Length of stay in pediatric intensive care unit
0.02
.04
1.02
1.00
1.04
Variable
administration of enteral feeding increased the risk for VAP 5- to almost 7-fold, and children who required emergency reintubation had an almost 3-fold greater risk for VAP than did children who did not require reintubation. In order to verify the combined influence of these variables on the development of VAP, variables that were significantly different (P ≤ .05) according to the univariate analysis were entered into an initial logistic regression model and then analyzed by using the forward stepwise method. Use of a postpyloric feeding tube, use of vasoactive drugs, and length of stay in the PICU were retained for the final logistic regression model (Table 3). The logistic regression coefficients revealed VAP was approximately 3 times more likely to develop in patients who were given vasoactive drugs or had a postpyloric feeding tube than in other patients. Moreover, each additional day of PICU hospitalization incrementally increased the probability of acquiring VAP by 2% (odds ratio, 1.02). These characteristics were considered independent risk factors for VAP.
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Discussion Studies that define risk factors for nosocomial infections have become increasingly relevant because they assist in the provision of subsidies relevant for establishing effective prevention programs, particularly for infants and children. Our analyses revealed that emergency reintubation, use of vasoactive drugs, presence of a nasoenteral tube, intermittent administration of enteral feeding, and prolonged hospitalization in the PICU are correlated with the development of VAP. We investigated several risk factors for VAP identified in other studies,9-14 such as genetic syndromes; interhospital transport; bronchoscopy; thoracentesis; use of immunosuppressors, corticosteroids, sedatives, and neuromuscular blockers; blood transfusions; and the presence of multiple catheters, but these risk factors were not associated with factors that were independently associated with VAP. Most of the children admitted to our PICU had severe underlying diseases, such as liver diseases, chronic pulmonary disease, renal failure, and primary or secondary immunodeficiency along with postoperative complications, particularly after cardiac and neurosurgical procedures. The severity of the patients’ conditions could explain the high rates of VAP. Other factors that could explain the rates observed are high rate of use of invasive procedures, presence in the PICU of professionals in training, shortage of proper material for procedures and surgeries, and the long mean length of stay in the PICU.15 The demographics, medical history, and hospitalization characteristics did not differ between the groups of children with and without VAP; however, we detected a trend toward an inverse association between infection and age. This result differs from the findings of studies conducted in developed countries but confirms the results found in studies in Brazil13 and Pakistan.14 According to Principi and Esposito,5 medications most frequently associated with the development of VAP are total parenteral nutritional formulas, steroids, and H2-receptor blockers. Additionally, many drugs, including antihypertensives, antihistamines, anticonvulsants, antineoplastics, sympathomimetics, and diuretics, can cause changes in salivary flow, the swallowing reflex, the ability to deliver self-care, systemic and local immune system functioning, and the physical and chemical properties of the microbial flora by modifying the microbial colonization
Several risk factors identified in other studies were not associated with ventilatorassociated pneumonia here.
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of the oral cavity, thus predisposing patients to VAP.16 We investigated several medications used routinely in intensive care; however, unlike other investigators,7-11 we did not detect an association between the use of any such medication and the development of VAP (with the sole exception of vasoactive drugs). Interestingly, we did not find any previously reported association between the use of vasoactive drugs and the occurrence of VAP. We assume that use of these drugs reflects the unstable clinical status that necessitates relatively long periods of mechanical ventilation and admission to the PICU, which themselves are factors that favor the occurrence of pneumonia. Other than emergency reintubation and enteral tube placement, none of the procedures done during hospitalization in the PICU were positively associated with the occurrence of VAP. Several researchers9-13 also consider invasive procedures to be risk factors for infection. Endotracheal tubes facilitate bacterial colonization of the tracheobronchial tree, the aspiration of contaminated secretions from the upper part of the airway, the accumulation of contaminated secretions above the cuff of the tracheal tube, and suppression of the cough reflex. Early-onset VAP may be related to the introduction of colonizing species from the oropharynx into the trachea during intubation.17 Researchers have described reintubation as a risk factor for VAP, and aspiration of gastrointestinal contents during this procedure is the most likely mechanism of infection.9,10 Additionally, use of aseptic technique may not be possible during emergency invasive procedures because of the critical nature of the situation.18 In a study in India,19 reintubation within 72 hours of extubation was asssociated with an increased tendency for the development of VAP. In our study, emergency reintubation was a significant risk factor for VAP. Development of a respiratory infection prolongs the duration of mechanical ventilation, and vice versa. According to Foglia et al,11 the incidence of VAP increases in patients who are intubated for a prolonged period. Among the children in our study, the ones in whom VAP developed received mechanical ventilation longer than did those in whom the disease did not develop. This finding was similar to results of recent studies done in India19 and Pakistan.14 This finding highlights the need to implement bundles to prevent VAP in the PICU. In a recent study,20 implementation of a multidimensional infection control program was associated with a significant reduction in the VAP rate in PICUs in developing countries. Components included in
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the program were active surveillance for VAP, adherence to hand hygiene guidelines, keeping patients in a semirecumbent position (30º-45º head-of-bed elevation), daily assessment of readiness to be weaned from mechanical ventilation and use of weaning protocols, regular oral care with an antiseptic solution, use of noninvasive ventilatory support whenever possible, minimizing the duration of mechanical ventilation, preference for orotracheal intubation over nasotracheal intubation, maintaining endotracheal cuff pressure at 20 cm H2O at least, removing condensate from ventilator circuits, keeping the ventilator circuit closed during removal of condensate, changing the ventilator circuit only when the circuit was visibly soiled or malfunctioning, avoiding gastric overdistention, avoiding use of H2-receptor blocking agents and proton pump inhibitors, and using sterile water to rinse reusable respiratory equipment.20 Similarly, VAP has been associated with an increased length of stay in the hospital and the PICU, a finding confirmed in our study. In a cohort study in a PICU,21 VAP was associated with a 56% increase in the PICU length of stay and a 43% increase in the total hospital length of stay. In our study, most likely VAP increased the PICU length of stay rather than the length of stay increasing the incidence of VAP. Nutritional support has become an essential component in the care of critically ill patients, because malnutrition increases morbidity and mortality rates and the hospital length of stay.22 Enteral nutrition is generally preferred over parenteral nutrition because the former reduces the risk for infectious complications related to the use of central venous catheters. However, use of gastric and postpyloric feeding tubes leads to an increased risk for gastric reflux, bronchoaspiration, sinusitis, and a high growth rate of pathogens, leading to the subsequent development of respiratory infections, including pneumonia.1 To date, no consensus exists among researchers on the most appropriate method to administer enteral feedings in patients at risk for VAP. Continuous administration of feedings may cause lasting changes in gastric pH, thereby predisposing the patient to the proliferation of bacteria (in particular, gram-negative bacteria), whereas intermittent administration can lead to gastric distension, gastric reflux, and bronchoaspiration because of the larger volume of nutritional formula given.1 In our study, both intermittent administration of nutritional formula and the presence of a enteral tube were risk factors for VAP. Risk factors for VAP in infants and children vary widely depending on the study. The factors common to most studies are usually extrinsic to the
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patient and occur subsequent to the implementation of intensive therapy. However, nearly all studies have indicated that the occurrence of VAP increases the duration of mechanical ventilation and increases the duration of both the PICU and the hospital stay, thereby resulting in increased health care costs and increased stress and trauma for the children and their families. In this regard, VAP is a major challenge that intensive care professionals face in their daily practice. Therefore these professionals need to determine the most efficient and safe care for their patients and to adopt measures that will narrow the gap between new theories and practice. The main limitations of our study were concomitant entry of the sample in a clinical trial, the size of the sample, and use of patients from a single PICU. Thus, the results could reflect characteristics specific to our sample. However, few data are available on infants and children, especially data on attributed VAP risk factors and outcomes in developing countries. Furthermore, we identified risk factors for the development of VAP in a PICU with professionals in training and with a shortage of basic material for procedures, as occurs in other developing countries. Comparisons of the structural factors of health care systems that can compromise patient safety have become increasingly relevant.
These data highlight the need to implement prevention bundles surveillance in the pediatric intensive care unit.
Conclusions We determined risk factors for VAP in infants and children. Univariate analysis revealed a significant association between the occurrence of VAP and the use of a nasoenteral tube, intermittent administration of nutritional formula, emergency reintubation, use of vasoactive drugs, duration of mechanical ventilation, and length of stay in both the PICU and the hospital. Logistic regression analysis indicated that use of vasoactive drugs, presence of a nasoenteral tube, and PICU length of stay were independent risk factors for VAP in infants and children. ACKNOWLEDGMENTS The work was performed at Hospital São Paulo and Pediatric Nursing Department, Escola Paulista de Enfermagem, Universidade Federal de São Paulo. We thank the children and their legal representatives for the children’s participation in this study. We also thank Prof Werther Brunow de Carvalho, Lucio F.P. Lima, and Marcelo L. Abramczyk for their cooperation in the study and their support in making VAP diagnoses, and the medical and nursing staff in the PICU.
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FINANCIAL DISCLOSURES This study was funded in part by grant 04-13361-2 from Fundação de Amparo a Pesquisa do Estado de São Paulo. eLetters Now that you’ve read the article, create or contribute to an online discussion on this topic. Visit www.ajcconline.org and click “Responses” in the second column of either the full-text or PDF view of the article.
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unit in Saudi Arabia: a 30-month prospective surveillance. Infect Control Hosp Epidemiol. 2004;25(9):753-758. Foglia E, Meier MD, Elward A. Ventilator-associated pneumonia in neonatal and pediatric intensive care unit patients. Clin Microbiol Rev. 2007;20(3):409-425. Srinivasan R, Asselin J, Gildengorin G, Wiener-Kronish J, Flori HR. A prospective study of ventilator-associated pneumonia in children. Pediatrics. 2009;123(4);1108-1115. Casado RJ, de Mello MJ, de Aragão RC, de Albuquerque Mde F, Correia JB. Incidence and risk factors for health care-associated pneumonia in a pediatric intensive care unit. Crit Care Med. 2011;39(8):1968-1973. Hamid MH, Malik MA, Masood J, Zia A, Ahmad TM. Ventilator-associated pneumonia in children. Coll Physicians Surg Pak. 2012;22(3):155-158. Abramczyk ML, Carvalho WB, Carvalho ES, Medeiros EA. Nosocomial infection in a pediatric intensive care unit in a developing country. Braz J Infect Dis. 2003;7(6):375-380. McNeill HE. Biting back at poor oral hygiene. Intensive Crit Care Nurs. 2000;16(6):367-372. Pedreira MLG, Kusahara DM, Carvalho WB, Núñez SC, Peterlini MAS. Oral care interventions and oropharyngeal colonization in children receiving mechanical ventilation. Am J Crit Care. 2009;18(4):319-328. Pyrek KM. Environmental services personnel can help break the chain of infection. Infection Control Today. November 1, 2002. http://www.infectioncontroltoday.com/articles/2002/11 /environmental-services-personnel-can-help-break-t.aspx. Accessed August 11, 2014. Awasthi S, Tahazzul M, Ambast A, Govil YC, Jain A. Longer duration of mechanical ventilation was found to be associated with ventilator-associated pneumonia in children aged 1 month to 12 years in India. J Clin Epidemiol. 2013;66(1):62-66. Rosenthal VD, Álvarez-Moreno C, Villamil-Gómez W, et al. Effectiveness of a multidimensional approach to reduce ventilator-associated pneumonia in pediatric intensive care units of 5 developing countries: International Nosocomial Infection Control Consortium findings. Am J Infect Control. 2012;40(6):497-501. Morrow BM, Argent AC. Ventilator-associated pneumonia in a paediatric intensive care unit in a developing country with high HIV prevalence. J Paediatr Child Health. 2009; 45(3):104-111. Artinian V, Krayem H, DiGiovine B. Effects of early enteral feeding on the outcome of critically ill mechanically ventilated medical patients. Chest. 2006;129(4):960-967.
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P ulmonary Critical Care
R
FACTORS FOR VENTILATOR-ASSOCIATED PNEUMONIA IN INFANTS AND CHILDREN: A CROSSSECTIONAL COHORT STUDY ISK
By Denise Miyuki Kusahara, RN, PhD, CCRN, Camila da Cruz Enz, RN, Ariane Ferreira Machado Avelar, RN, PhD, Maria Angélica Sorgini Peterlini, RN, PhD, and Mavilde da Luz Gonçalves Pedreira, RN, PhD, CCRN
©2014 American Association of Critical-Care Nurses doi: http://dx.doi.org/10.4037/ajcc2014127
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Background The epidemiology of ventilator-associated pneumonia is well described for adults, but little information is available on risk factors for this disease in children. Objective To identify predisposing factors for ventilatorassociated pneumonia in children. Methods A cross-sectional prospective cohort study of 96 patients in a 9-bed pediatric intensive care unit was performed. Variables examined were demographic characteristics, inpatient care, medications, nutrition, invasive procedures, and characteristics of mechanical ventilation. Data were analyzed by using Pearson χ2 analysis, Fisher exact and Mann-Whitney tests, odds ratios, and forward stepwise logistic regression. Results Occurrence of ventilator-associated pneumonia correlated positively with use of nasoenteral tubes (odds ratio, 5.278; P < .001), intermittent administration of nutritional formula (odds ratio, 6.632; P = .005), emergency reintubation (odds ratio, 2.700; P = .02), use of vasoactive drugs (odds ratio, 5.108; P = .009), duration of mechanical ventilation (P < .001), and length of stay in the pediatric intensive care unit (P < .001) and in the hospital (P = .01). Conclusion Use of vasoactive drugs, presence of a nasoenteral tube, and duration of stay in the pediatric intensive care unit were independent risk factors for ventilator-associated pneumonia. (American Journal of Critical Care. 2014;23:469-476)
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V
entilator-associated pneumonia (VAP) is defined as inflammation of the pulmonary parenchyma due to the action of an infectious agent. VAP occurs up to 48 hours after the initiation of mechanical ventilation in patients who had tracheal intubation and did not have pneumonia at the time of intervention.1 Health care– associated infections occur in approximately 12% of patients in the pediatric intensive care unit (PICU), and pneumonia is the second most common type of nosocomial infection, accounting for 22.7% of the infections in the PICU. VAP occurs in 9% to 27% of intubated patients, and the risk for VAP increases 1% to 3% for each day of mechanical ventilation. The mortality rate for patients with VAP is high, from 33% to 71%.1,2
The pathogens that cause VAP are able to overcome the mechanical, hormonal, and/or cellular defenses of the body, thereby invading, colonizing, and establishing an infection within the lower part of the respiratory tract. Microbial access to the otherwise sterile lower part of the respiratory tract can occur via 4 mechanisms: aspiration of pathogencontaining oropharyngeal secretions from the gastric cavity or sinuses, dissemination of organisms from a contiguous area such as the pleura, inhalation of contaminated aerosols after the use of respiratory therapy devices, and hematogenous spread from remote infection sites to the lung.3,4 The epidemiology and prognosis of VAP are well described in adults; however, little information is available for VAP in infants and children, especially attributed risk factors and outcomes such as morbidity, mortality, and cost. The information available comes primarily from studies conducted in developed countries. Although the incidence of VAP has decreased significantly in developed countries since the 1990s as a result of improved clinical knowledge and the successful implementation of preventive strategies,
Data were collected in a pediatric intensive care unit at São Paulo Hospital in Brazil.
About the Authors Denise Miyuki Kusahara is a pediatric critical care nurse, Ariane Ferreira Machado Avelar is an adjunct professor, Maria Angélica Sorgini Peterlini and Mavilde da Luz Gonçalves Pedreira are associate professors, Pediatric Nursing Department, and Camila da Cruz Enz is a registered nurse and a former scientific initiation fellow, Escola Paulista de Enfermagem, Universidade Federal de São Paulo, São Paulo, Brazil. Corresponding author: Denise Miyuki Kusahara, RN, PhD, Nursing School, Escola Paulista de Enfermagem, Universidade Federal de São Paulo, Rua Napoleão de Barros, 754, Office 113, São Paulo, Brazil CEP 04024002 (e-mail: [email protected]).
CCRN,
470
the incidence still remains high.5 Thus, additional studies are needed to determine the risk factors for VAP in PICU patients. The results from these studies would contribute to improving the standard of care for children undergoing mechanical ventilation. In this context, the primary objective of this study was to identify risk factors for the development of VAP related either to the patient or to the care given in the PICU.
Methods The study was a cross-sectional prospective cohort investigation. The study is part of a randomized clinical trial to test the effectiveness of oral care with 0.12% chlorhexidine in decreasing VAP in critically ill children. In the clinical trial, use of 0.12% chlorhexidine did not significantly modify the incidence of VAP in a sample of children.6 Site and Study Sample The data were collected in a 9-bed PICU at São Paulo Hospital, a 700-bed tertiary care nonprofit hospital affiliated with the Federal University of São Paulo, São Paulo, Brazil. All the patients and/or their legal representatives who consented to participate in a prospective, randomized controlled trial study (Clinical Trials Identifier: NCT01083407) were recruited for the study. Children were included in the sample if they were expected to remain intubated and treated with mechanical ventilation for more than 24 hours. Patients were excluded if they were newborns, had a tracheostomy, had a diagnosis of pneumonia on admission to the PICU, had been intubated longer than 24 hours before admission to the PICU, or declined consent. The sample comprised 96 children who fulfilled inclusion criteria. The data were prospectively collected from June 2005 to June 2008 onto a standardized form. At the time of data collection, the VAP prevention protocol in the PICU included
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Table 1 Agreement between the Centers for Disease Control and Prevention/National Healthcare Safety Network (CDC/NHSN) criteria and the Clinical Pulmonary Infection Score (CPIS) for diagnosis of ventilator-associated pneumonia (VAP)
elevation of the head of the bed 30º, interventions to prevent peptic ulcer disease, and standardized oral care. Site-specific algorithms for clinically or bacteriologically defined pneumonia, including serial chest radiographs, signs and symptoms, and laboratory findings were followed. Study Variables The outcome variable was defined as the occurrence of VAP. Development of VAP was quantified by using the Clinical Pulmonary Infection Score (CPIS) and confirmed by using the alternative pneumonia clinical criteria for infants and children defined by the Centers for Disease Control and Prevention and the National Healthcare Safety Network (CDC/NHSN). The CPIS is a clinical score of 0 to 12 based on the following 6 variables: temperature, blood leukocyte count, tracheal secretions, radiological pulmonary imaging, oxygenation, and microbiological data. Scores of 6 or greater are considered indicative of VAP.7 The CDC/NHSN diagnosis is based on serial chest radiographs, changes in body temperature, blood leukocyte count, oxygenation, lung auscultation, and characteristics of the pulmonary secretions.8 A physician determined these scores. When the CPIS and the CDC/NHSN scores did not agree, a second expert analyzed the data to determine the final diagnosis. Each episode of VAP was characterized as early or late onset. Early-onset VAP occurs during the first 4 days of mechanical ventilation and late-onset VAP develops 5 or more days after initiation of mechanical ventilation.1 Variables examined were intrinsic and extrinsic risk factors as described in the literature and included demographic characteristics, PICU hospitalization, drugs used, nutritional and intensive therapies, invasive procedures, pulmonary mechanical ventilation, and intubation characteristics. Statistical Analysis Categorical variables were analyzed by using both absolute and relative frequencies; continuous variables were analyzed on the basis of the median. Pearson χ2 and Fisher exact tests were used to compare the categorical variables. Numerical variables were analyzed by using the nonparametric MannWhitney test. The odds ratio with a 95% CI were calculated for the variables associated with a risk for VAP; these variables were identified as those with P ≤ .05 in the univariate analysis. These same variables were selected for inclusion in a stepwise forward logistic regression model. Variables that were not significant (ie, P > .05) when analyzed jointly were not included in the final analysis.
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VAP according to CDC/NHSNa VAP according to CPIS Absent Present a
Absent
Present
64 (67) 1(1)
4 (4) 27 (28)
Values in second and third column are number (%) of cases. κ = 0.878, P < .001.
Results Among the 96 children in the sample, VAP developed in 31 (32%), with an incidence of 16.4 episodes per 1000 days of mechanical ventilation. A strong agreement existed between the CDC/NHSN criteria and CPIS for the VAP diagnoses (κ statistic, 0.878; P < .001). The concordance was present in 91 analyses (95%; Table 1). Early-onset VAP was identified in 19 of the 31 children (61%) and late-onset VAP in 12 (39%). The mean CPIS scores were 3.8 (SD, 0.70) for the 68 VAP-free patients and 6.2 (SD, 0.70) for the 31 patients who had VAP. Mean total leukocyte count was significantly higher (P = .005) in children with VAP (17 000/μL; SD, 9644/μL) than in VAP-free children (10 796/μL; SD, 5238/μL). The primary causative bacterial species detected in samples of oropharyngeal and tracheal secretions were Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Enterobacter sp, Escherichia coli, and Staphylococcus aureus. No instances of VAP caused by fungi were identified in this sample of children. The median age of all patients was 28 months (range, 1-201 months), and most of the children were boys (64%). At the time of admission to the PICU, the median of the Nine Equivalents of Nursing Manpower Use Score was 31.5. The children were admitted to the PICU mainly after cardiac surgery (25%); gastrointestinal surgery (17%); trauma, brain injury, or neurological problems (17%), renal conditions (16%), respiratory diseases (9%), hematological disorders (10%), and endocrinologic disorders (6%). Of the 96 children, 34 (35%) had an enteral feeding tube, and 58 (60%) had a nasogastric tube (55% for feeding and 45% for gastric decompression). All 96 children had the head of the bed elevated at least 30º and had no clinical evidence of aspiration during the study period. Only 30 of the 96 children (31%) had a cuffed tracheal tube. The distribution frequencies and univariate analysis of the demographic characteristics upon admission to the PICU; drug, nutritional, and intensive therapies; invasive procedures; duration of mechanical ventilation; and endotracheal intubation for the 2 groups are given in Table 2.
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Table 2 Frequency distribution and univariate analysis of children with and without ventilator-associated pneumonia (VAP) No. (%) of patients Without VAP (n = 65)
Variable Age, months Mean (SD) Median Minimum-maximum
With VAP (n = 31)
Odds ratio
95% CI
P .07a
57.0 (58.2) 30.0 1-192
35.0 (48.1) 12.5 1-165
Male sex
44 (68)
17 (55)
Nutritional conditional Malnutrition Normal
31 (48) 34 (52)
17 (55) 14 (45)
Hospitalization within preceding 30 days
16 (25)
7 (23)
.74b
6 (9)
3 (10)
>.99c
Chronic disease
33 (51)
17 (55)
.88b
Emergency admission to pediatric intensive care unit
42 (65)
13 (42)
.06b
Diagnosis on admission Medical Surgical Infectious
45 (69) 39 (60) 24 (37)
21 (68) 18 (58) 16 (52)
.64b .66b .11b
Injured gums and oral mucosa
4 (6)
5 (16)
.15c
Abnormal, decayed, missing, and filled teeth index
9 (14)
3 (10)
.74c
Oral care with chlorhexidine digluconate 0.12%
31 (48)
15 (48)
.95b
Invasive procedures Central venous catheterization Transcardiac catheterization Arterial catheterization Intracranial monitoring Thoracentesis Bronchoscopy Thoracic drainage Hemodialysis
55 (85) 11 (17) 30 (46) 11 (17) 4 (6) 3 (5) 18 (28) 7 (11)
26 (84) 7 (23) 10 (32) 2 (6) 0 (0) 1 (3) 8 (26) 1 (3)
Tracheal intubation Orotracheal intubation Emergency reintubation Elective reintubation Uncuffed tracheal tube
65 (100) 11 (17) 10 (15) 42 (65)
31 (100) 11 (35) 07 (23) 24 (77)
Mechanical ventilation, h Mean (SD) Median Minimum-maximum
134.0 (84.3) 120 14-40
349.5 (277.0) 264 15-35
.001a
Transportation
36 (55)
18 (58)
.34b
Nutritional therapy Postpyloric tube Nasogastric tube To prevent gastric distention To provide nutritional support Continuous administration of diet Intermittent administration of diet
15 41 18 23 1 38
(23) (63) (44) (56) (2) (58)
19 (61) 17 (55) 8 (47) 9 (52) 1 (3) 28 (90)
Drug and intravenous therapy Antibiotic Sedative Analgesic Neuromuscular blocker Immunosuppressant Corticosteroids Antacids Vasoactive drugs Hemoderivatives
65 (100) 56 (86) 61 (94) 4 (6) 2 (3) 26 (40) 58 (89) 37 (57) 39 (60)
31 (100) 31 (100) 30 (97) 5 (16) 2 (6) 17 (55) 28 (90) 27 (87) 23 (74)
Previous pulmonary disease
.29b .66b
>.99b .27b .31b .40c .55c .99c .87b .42c
2.700
1.012-7.200
5.278
2.093-13.310
6.632
1.827-24.070
5.108
1.602-16.286
>.99b .02b .20b .40b
.001b .30b .82b >.99c .005b .33b .26b >.99b .16c .60c .17b .73b .009b .29b Continued
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Table 2 Continued No. (%) of patients Without VAP (n = 65)
Variable Mortality
c
P
95% CI
.07c
17 (26)
3 (10)
7.55 (4.6) 7 1-21
24.5 (26.5) 17 4-150 .01a
Length of hospitalization Mean (SD) Median Minimum-maximum
b
Odds ratio
.001a
Length of stay in pediatric intensive care unit Mean (SD) Median Minimum-maximum
a
With VAP (n = 31)
24.1 (23.3) 16.5 3-132
59.3 (70.4) 35 2-380
Nonparametric Mann-Whitney test. χ2 test. Fisher exact test.
Children with VAP tended to be younger than those without VAP, but the difference was not statistically significant (P = .07). Children with VAP did not differ significantly from children without VAP for the variables related to baseline characteristics and hospitalization. The 2 groups also did not differ significantly for nutritional status (according to the z score), previous hospitalization, previous pulmonary or chronic disease, and the type of diagnosis at admission. Similarly, the 2 groups did not differ significantly in use of invasive procedures (eg, central or peripheral venous catheterization, thoracic drainage, bronchoscopy, hemodialysis). Moreover, no significant difference was detected between the groups for intrahospital transfers; slightly more than half of the children with VAP required transportation during their stay in the PICU. In contrast, the 2 groups differed significantly for factors related to intensive treatment. Compared with children without VAP, a higher percentage of children with VAP received vasoactive drugs (P = .009), required an emergency reintubation (P = .02), or were fed via a postpyloric tube (P < .001) with intermittent administration of nutritional formula (P = .005). Compared with children without VAP, children with VAP had significantly greater duration of mechanical ventilation (P < .001) and significantly longer stays in both the PICU (P < .001) and the hospital (P = .01). Independent variables associated with the outcome variable were further analyzed to determine the odds ratio (Table 2). Use of vasoactive drugs, use of postpyloric tubes for nutritional therapy, and intermittent
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Table 3 Logistic regression model for the development of ventilator-associated pneumonia among critically ill children Coefficient
P
Odds ratio
Lower limit
Upper limit
Use of postpyloric feeding tube
1.19
.04
3.29
1.05
10.28
Use of vasoactive drugs
1.26
.05
3.52
1.01
12.25
Length of stay in pediatric intensive care unit
0.02
.04
1.02
1.00
1.04
Variable
administration of enteral feeding increased the risk for VAP 5- to almost 7-fold, and children who required emergency reintubation had an almost 3-fold greater risk for VAP than did children who did not require reintubation. In order to verify the combined influence of these variables on the development of VAP, variables that were significantly different (P ≤ .05) according to the univariate analysis were entered into an initial logistic regression model and then analyzed by using the forward stepwise method. Use of a postpyloric feeding tube, use of vasoactive drugs, and length of stay in the PICU were retained for the final logistic regression model (Table 3). The logistic regression coefficients revealed VAP was approximately 3 times more likely to develop in patients who were given vasoactive drugs or had a postpyloric feeding tube than in other patients. Moreover, each additional day of PICU hospitalization incrementally increased the probability of acquiring VAP by 2% (odds ratio, 1.02). These characteristics were considered independent risk factors for VAP.
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Discussion Studies that define risk factors for nosocomial infections have become increasingly relevant because they assist in the provision of subsidies relevant for establishing effective prevention programs, particularly for infants and children. Our analyses revealed that emergency reintubation, use of vasoactive drugs, presence of a nasoenteral tube, intermittent administration of enteral feeding, and prolonged hospitalization in the PICU are correlated with the development of VAP. We investigated several risk factors for VAP identified in other studies,9-14 such as genetic syndromes; interhospital transport; bronchoscopy; thoracentesis; use of immunosuppressors, corticosteroids, sedatives, and neuromuscular blockers; blood transfusions; and the presence of multiple catheters, but these risk factors were not associated with factors that were independently associated with VAP. Most of the children admitted to our PICU had severe underlying diseases, such as liver diseases, chronic pulmonary disease, renal failure, and primary or secondary immunodeficiency along with postoperative complications, particularly after cardiac and neurosurgical procedures. The severity of the patients’ conditions could explain the high rates of VAP. Other factors that could explain the rates observed are high rate of use of invasive procedures, presence in the PICU of professionals in training, shortage of proper material for procedures and surgeries, and the long mean length of stay in the PICU.15 The demographics, medical history, and hospitalization characteristics did not differ between the groups of children with and without VAP; however, we detected a trend toward an inverse association between infection and age. This result differs from the findings of studies conducted in developed countries but confirms the results found in studies in Brazil13 and Pakistan.14 According to Principi and Esposito,5 medications most frequently associated with the development of VAP are total parenteral nutritional formulas, steroids, and H2-receptor blockers. Additionally, many drugs, including antihypertensives, antihistamines, anticonvulsants, antineoplastics, sympathomimetics, and diuretics, can cause changes in salivary flow, the swallowing reflex, the ability to deliver self-care, systemic and local immune system functioning, and the physical and chemical properties of the microbial flora by modifying the microbial colonization
Several risk factors identified in other studies were not associated with ventilatorassociated pneumonia here.
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of the oral cavity, thus predisposing patients to VAP.16 We investigated several medications used routinely in intensive care; however, unlike other investigators,7-11 we did not detect an association between the use of any such medication and the development of VAP (with the sole exception of vasoactive drugs). Interestingly, we did not find any previously reported association between the use of vasoactive drugs and the occurrence of VAP. We assume that use of these drugs reflects the unstable clinical status that necessitates relatively long periods of mechanical ventilation and admission to the PICU, which themselves are factors that favor the occurrence of pneumonia. Other than emergency reintubation and enteral tube placement, none of the procedures done during hospitalization in the PICU were positively associated with the occurrence of VAP. Several researchers9-13 also consider invasive procedures to be risk factors for infection. Endotracheal tubes facilitate bacterial colonization of the tracheobronchial tree, the aspiration of contaminated secretions from the upper part of the airway, the accumulation of contaminated secretions above the cuff of the tracheal tube, and suppression of the cough reflex. Early-onset VAP may be related to the introduction of colonizing species from the oropharynx into the trachea during intubation.17 Researchers have described reintubation as a risk factor for VAP, and aspiration of gastrointestinal contents during this procedure is the most likely mechanism of infection.9,10 Additionally, use of aseptic technique may not be possible during emergency invasive procedures because of the critical nature of the situation.18 In a study in India,19 reintubation within 72 hours of extubation was asssociated with an increased tendency for the development of VAP. In our study, emergency reintubation was a significant risk factor for VAP. Development of a respiratory infection prolongs the duration of mechanical ventilation, and vice versa. According to Foglia et al,11 the incidence of VAP increases in patients who are intubated for a prolonged period. Among the children in our study, the ones in whom VAP developed received mechanical ventilation longer than did those in whom the disease did not develop. This finding was similar to results of recent studies done in India19 and Pakistan.14 This finding highlights the need to implement bundles to prevent VAP in the PICU. In a recent study,20 implementation of a multidimensional infection control program was associated with a significant reduction in the VAP rate in PICUs in developing countries. Components included in
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the program were active surveillance for VAP, adherence to hand hygiene guidelines, keeping patients in a semirecumbent position (30º-45º head-of-bed elevation), daily assessment of readiness to be weaned from mechanical ventilation and use of weaning protocols, regular oral care with an antiseptic solution, use of noninvasive ventilatory support whenever possible, minimizing the duration of mechanical ventilation, preference for orotracheal intubation over nasotracheal intubation, maintaining endotracheal cuff pressure at 20 cm H2O at least, removing condensate from ventilator circuits, keeping the ventilator circuit closed during removal of condensate, changing the ventilator circuit only when the circuit was visibly soiled or malfunctioning, avoiding gastric overdistention, avoiding use of H2-receptor blocking agents and proton pump inhibitors, and using sterile water to rinse reusable respiratory equipment.20 Similarly, VAP has been associated with an increased length of stay in the hospital and the PICU, a finding confirmed in our study. In a cohort study in a PICU,21 VAP was associated with a 56% increase in the PICU length of stay and a 43% increase in the total hospital length of stay. In our study, most likely VAP increased the PICU length of stay rather than the length of stay increasing the incidence of VAP. Nutritional support has become an essential component in the care of critically ill patients, because malnutrition increases morbidity and mortality rates and the hospital length of stay.22 Enteral nutrition is generally preferred over parenteral nutrition because the former reduces the risk for infectious complications related to the use of central venous catheters. However, use of gastric and postpyloric feeding tubes leads to an increased risk for gastric reflux, bronchoaspiration, sinusitis, and a high growth rate of pathogens, leading to the subsequent development of respiratory infections, including pneumonia.1 To date, no consensus exists among researchers on the most appropriate method to administer enteral feedings in patients at risk for VAP. Continuous administration of feedings may cause lasting changes in gastric pH, thereby predisposing the patient to the proliferation of bacteria (in particular, gram-negative bacteria), whereas intermittent administration can lead to gastric distension, gastric reflux, and bronchoaspiration because of the larger volume of nutritional formula given.1 In our study, both intermittent administration of nutritional formula and the presence of a enteral tube were risk factors for VAP. Risk factors for VAP in infants and children vary widely depending on the study. The factors common to most studies are usually extrinsic to the
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patient and occur subsequent to the implementation of intensive therapy. However, nearly all studies have indicated that the occurrence of VAP increases the duration of mechanical ventilation and increases the duration of both the PICU and the hospital stay, thereby resulting in increased health care costs and increased stress and trauma for the children and their families. In this regard, VAP is a major challenge that intensive care professionals face in their daily practice. Therefore these professionals need to determine the most efficient and safe care for their patients and to adopt measures that will narrow the gap between new theories and practice. The main limitations of our study were concomitant entry of the sample in a clinical trial, the size of the sample, and use of patients from a single PICU. Thus, the results could reflect characteristics specific to our sample. However, few data are available on infants and children, especially data on attributed VAP risk factors and outcomes in developing countries. Furthermore, we identified risk factors for the development of VAP in a PICU with professionals in training and with a shortage of basic material for procedures, as occurs in other developing countries. Comparisons of the structural factors of health care systems that can compromise patient safety have become increasingly relevant.
These data highlight the need to implement prevention bundles surveillance in the pediatric intensive care unit.
Conclusions We determined risk factors for VAP in infants and children. Univariate analysis revealed a significant association between the occurrence of VAP and the use of a nasoenteral tube, intermittent administration of nutritional formula, emergency reintubation, use of vasoactive drugs, duration of mechanical ventilation, and length of stay in both the PICU and the hospital. Logistic regression analysis indicated that use of vasoactive drugs, presence of a nasoenteral tube, and PICU length of stay were independent risk factors for VAP in infants and children. ACKNOWLEDGMENTS The work was performed at Hospital São Paulo and Pediatric Nursing Department, Escola Paulista de Enfermagem, Universidade Federal de São Paulo. We thank the children and their legal representatives for the children’s participation in this study. We also thank Prof Werther Brunow de Carvalho, Lucio F.P. Lima, and Marcelo L. Abramczyk for their cooperation in the study and their support in making VAP diagnoses, and the medical and nursing staff in the PICU.
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FINANCIAL DISCLOSURES This study was funded in part by grant 04-13361-2 from Fundação de Amparo a Pesquisa do Estado de São Paulo. eLetters Now that you’ve read the article, create or contribute to an online discussion on this topic. Visit www.ajcconline.org and click “Responses” in the second column of either the full-text or PDF view of the article.
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