Risk factors for mortality in ventilator-associated tracheobronchitis: a case-control study / Fatores de risco para mortalidade em traqueobronquite associada à ventilação mecânica: estudo caso-controle

ABSTRACT Objective To describe the microbiological characteristics and to assess the risk factors for mortality of ventilator-associated tracheobronchitis in a case-control study of intensive care patients. Methods This case-control study was conducted over a 6-year period in a 40-bed medical-surgical intensive care unit in a tertiary care, private hospital in São Paulo, Brazil. Case patients were identified using the Nosocomial Infection Control Committee database. For the analysis of risk factors, matched control subjects were selected from the same institution at a 1:8.8 ratio, between January 2006 and December 2011. Results A total of 40 episodes of ventilator-associated tracheobronchitis were evaluated in 40 patients in the intensive care unit, and 354 intensive care patients who did not experience tracheobronchitis were included as the Control Group. During the 6-year study period, a total of 42 organisms were identified (polymicrobial infections were 5%) and 88.2% of all the microorganisms identified were Gram-negative. Using a logistic regression model, we found the following independent risk factors for mortality in ventilator-associated tracheobronchitis patients: Acute Physiology and Chronic Health Evaluation I score (odds ratio 1.18 per unit of score; 95%CI: 1.05-1.38; p=0.01), and duration of mechanical ventilation (odds ratio 1.09 per day of mechanical ventilation; 95%CI: 1.03-1.17; p=0.004). Conclusion Our study provided insight into the risk factors for mortality and microbiological characteristics of ventilator-associated tracheobronchitis.

RESUMO Objetivo Descrever as características microbiológicas e avaliar os fatores de risco para mortalidade na traqueobronquite associada à ventilação mecânica em um estudo caso-controle de pacientes de terapia intensiva. Métodos Estudo realizado ao longo de 6 anos em uma unidade de terapia intensiva médico-cirúrgica de 40 leitos, em um hospital privado e de nível terciário em São Paulo, Brasil. O Grupo Caso foi identificado usando o banco de dados da Comissão de Controle de Infecção Hospitalar. O Grupo Controle foi pareado na proporção de 1:8,8 entre janeiro de 2006 e dezembro de 2011. Resultados Quarenta episódios de traqueobronquites associadas à ventilação foram avaliados em 40 pacientes na unidade de terapia intensiva, e 354 pacientes não apresentaram traqueobronquite Grupo Controle. Foram identificados 42 microrganismos (dos quais 5% foram infecções polimicrobianas), sendo que 88,2% de todos os microrganismos eram bactérias Gram-negativas. Usando um modelo de regressão logística, encontramos os seguintes fatores de risco independentes para mortalidade em pacientes com traqueobronquites associadas à ventilação: pontuação da Acute Physiology and Chronic Health Evaluation I (odds ratio 1,18 por uma unidade de pontuação; IC95%: 1,05-1,38; p=0,01) e duração da ventilação mecânica (odds ratio 1,09 por dia de ventilação mecânica; IC95%: 1,03-1,17; p=0,004). Conclusão Nosso estudo forneceu informações sobre os fatores de risco para mortalidade e características microbiológicas da traqueobronquite associada à ventilação mecânica.

Performance of ICU ventilators during noninvasive ventilation with large leaks in a total face mask: a bench study / Desempenho de ventiladores de UTI durante ventilação não invasiva com grandes vazamentos em máscara facial total: estudo em simulador mecânico

Objective: Discomfort and noncompliance with noninvasive ventilation (NIV) interfaces are obstacles to NIV success. Total face masks (TFMs) are considered to be a very comfortable NIV interface. However, due to their large internal volume and consequent increased CO2 rebreathing, their orifices allow proximal leaks to enhance CO2 elimination. The ventilators used in the ICU might not adequately compensate for such leakage. In this study, we attempted to determine whether ICU ventilators in NIV mode are suitable for use with a leaky TFM. Methods: This was a bench study carried out in a university research laboratory. Eight ICU ventilators equipped with NIV mode and one NIV ventilator were connected to a TFM with major leaks. All were tested at two positive end-expiratory pressure (PEEP) levels and three pressure support levels. The variables analyzed were ventilation trigger, cycling off, total leak, and pressurization. Results: Of the eight ICU ventilators tested, four did not work (autotriggering or inappropriate turning off due to misdetection of disconnection); three worked with some problems (low PEEP or high cycling delay); and one worked properly. Conclusions: The majority of the ICU ventilators tested were not suitable for NIV with a leaky TFM. .

Objetivo: O desconforto e a falta de adaptação às interfaces de ventilação não invasiva (VNI) são obstáculos ao sucesso da VNI. A máscara facial total (MFT) é uma interface de VNI considerada muito confortável. No entanto, devido a seu grande volume interno e, consequentemente, ao aumento da reinalação de CO2, a MFT tem orifícios que permitem vazamentos proximais para melhorar a eliminação de CO2. É possível que os ventiladores usados na UTI não compensem esse vazamento adequadamente. Neste estudo, buscamos determinar se ventiladores de UTI com módulo de VNI podem ser usados com MFT com grandes vazamentos. Métodos: Estudo em simulador mecânico conduzido em um laboratório universitário de pesquisa. Oito ventiladores de UTI equipados para realizar VNI e um ventilador específico para VNI foram conectados a uma MFT com grandes vazamentos. Todos foram testados com dois níveis de positive end-expiratory pressure (PEEP, pressão expiratória final positiva) e três níveis de pressão de suporte. As variáveis analisadas foram disparo do ventilador, ciclagem, vazamento total e pressurização. Resultados: Dos oito ventiladores de UTI, quatro não funcionaram (autodisparo ou desligamento inapropriado por detecção incorreta de desconexão), três funcionaram com alguns problemas (valores baixos de PEEP ou grande atraso na ciclagem do ventilador) e apenas um funcionou adequadamente. Conclusões: A maioria dos ventiladores de UTI testados mostrou-se inadequada para VNI com MFT com grandes vazamentos. .

Evaluation of staff education on ventilator bundle compliance in university Kebangsaan Malaysia medical centre [UKMMC] intensive care unit [ICU]

Ventilator associated pneumonia [VAP] has been associated with high morbidity and mortality rates especially in critically ill patients. Implementing the "ventilator bundle" series of interventions serves a pivotal role in reducing the incidence of VAP. This study was carried out to review compliance of the staff in UKMMC ICU towards ventilator bundle from August 2010 to March 2011. All medical and nursing staffs in ICU were given education by means of lectures, pamphlets, posters, and refresher sessions which were implemented in between two periods of assessment Compliance was assessed on daily basis at random throughout a 140-day course divided into 70 pre-educational days and 70 post-educational days. Pre-educational overall compliance achieved was 38.4%. Compliance of individual component was: [1] head of bed [HOB] > 30 degrees: 43.6%, [2] Peptic ulcer disease [PUD] prophylaxis: 88.6% [3] Deep venous thrombosis [DVT] prophylaxis: 86.7% [4] Sedation vacation: 98.1% [5] Oral care: 96.7%. Post-educational overall compliance achieved was 65.0% with each individual component achieving 67.6%, 97.7%, 89.6%, 97.4%, and 99.0% respectively. There were statistically significant increases [p<0.05] in overall compliance and 3 individual components i.e. HOB elevation, PUD prophylaxis and oral care. Implementation of education had resulted in improved compliance of some, but not all components of the ventilator bundle. Continuous staff education is recommended to ensure further improvement and maintenance in compliance amongst the multidisciplinary team who manage patients in ICU

Avaliação do desempenho de diferentes interfaces para ventilação não invasiva em modelo mecânico simulando paciente com DPOC / Performance of different interfaces for noninvasive ventilation (NPPV) in a lung model simulating a COPD patient

Ventilação mecânica não invasiva (VNI) é medida de suporte ventilatório comumente utilizada em pacientes com Doença Pulmonar Obstrutiva Crônica (DPOC). O objetivo deste estudo é comparar o desempenho de três interfaces para VNI em termos de sincronia paciente-ventilador. Utilizamos um simulador mecânico de pulmão alimentado e acoplado a uma cabeça de manequim para simular um paciente com DPOC em VNI. Três máscaras com volumes internos de 366, 550 e 1500 mL foram testadas. Os resultados mostraram que as máscaras com menor volume interno tiveram menor vazamento e consequentemente melhor sincronia com o simulador, com atraso de disparo mais curto (131 e 128ms vs 153ms) e aceleração de fluxo mais rápida (138 e 143ms vs 161ms). Concluímos que o tipo de interface usado para VNI tem impacto na sincronia e sua escolha pode ser guiada pela maior necessidade de aliviar o trabalho respiratório.

Noninvasive ventilation (NPPV) is frequently used in Chronic Obstructive Pulmonary Disease (COPD). The aim of this study is to compare the performance of three NPPV interfaces interms of patient-ventilator synchrony. We used a lung simulator attached to a mannequin head to simulate a COPD patient on NPPV. Three interfaces with inner volumes of 366, 550 and 1500 mL were tested. Results showed that the interface with larger inner volume had higher air leakage, while smaller inner volume interfaces had better synchrony with the simulator, with shorter trigger delay (131 e 128ms vs 153ms) and faster flow acceleration (138 e 143ms vs 161ms). We conclude that the type of interface used for NPPV has an impact on synchrony, and the choice of the interface may be based on the need to or unload respiratory muscles.

Characterisation of aerobic bacteria isolated from endotracheal aspirate in adult patients suspected ventilator associated pneumonia in a tertiary care center in Mangalore

Despite advances in antimicrobial therapy, better supportive care modalities and use of a wide range of preventive measures, ventilator-associated pneumonia [VAP] continues to be an important cause of morbidity and mortality in intensive care unit [ICU]. VAP requires a rapid diagnosis and initiation of appropriate antibiotic treatment, to prevent mortality and morbidity. Inappropriate and inadequate antibiotic treatment causes emergence of drug resistance in pathogens and poor prognosis in patients. Early detection of pathogens causing VAP helps to control their spread by administration of suitable antibiotics and proper infection control measures. The study was conducted to know the pathogens causing VAP in Fr. Muller Medical College Hospital, Mangalore, and their susceptibility pattern. A total of 100 patients, on mechanical ventilation for more than 48 h, who were suspected to have VAP were included in the study between December 2008 and November 2009. Their endotracheal aspirates [ETAs] were collected and processed. From 100 ETA, 138 isolates of count >10[5] CFU/ mL were characterized and antibiogram was determined using standard antibiotics regime. Incidence of VAP was found to be 44.2% among the mechanically ventilated patients. Klebsiella pneumoniae [34%] was the most common pathogen isolated, followed by Pseudomonas aeruginosa [20%]. Among them, most of the K. pneumoniae and P. aeruginosa isolates were resistant to penicillins, cephalosporins, fluoroquinolones was observed but were sensitive to piperacillin/tazobactum, cefaperazone/sulbactum, and carbapenems. All isolates were sensitive to amikacin. The present study shows prevalence of multidrug-resistant organisms in the study region. Klebsiella species was the most common pathogen isolated in ETA. Acinetobacter species were the most resistant pathogens prevailing in our ICU setup, leading to the increased mortality in the ventilated patients. Patients with chronic obstructive pulmonary disease is the most common predisposing factor for VAP in the study group

Device-associated infection rates and bacterial resistance in the intensive care units of a Turkish referral hospital

To determine device-associated infection [DAT] rates, and the microbiological and antibiotic resistance profiles of infecting pathogens in our hospital. Prospective surveillance of healthcare-associated infections was performed from January 2007 to March 2010 in 4 different intensive care units [ICUs] of SB Diskapi Yildirim Beyazit Training and Research Hospital, Ankara, Turkey. During the study period, 6,005 patients were followed-up in ICUs for a total of 46,355 patient-days. The total number of DATs was 969. Catheter-associated urinary tract infection [CAUTI] was the most common DAI [55.3% of DAIs; 11.9 cases per 1000 catheter-days], followed by ventilator-associated pneumonia [VAP] [38.9% of DAIs; 21.2 cases per 1000 ventilator-days], and central line-associated blood stream infection [CLABSI] [5.8% of DAIs; 2.8 cases per 1000 central line-days]. The most frequently isolated pathogens in patients with VAP were Acinetobacter species [24.5%] and Escherichia coli in CAUTI [24.2%]. Coagulase negative Staphylococci and Candida species were the leading pathogens in patients with CLABSI. We observed considerably high rates of VAP and CAUTI and a high rate of CLABSI in our ICUs when compared with the National Healthcare Safety Network data. These findings emphasize the need to improve infection control practices and management of invasive device use in our hospital

Interação paciente ventilador nas diferentes fases do ciclo ventilatório em ventilação por pressão de suporte / Patient-ventilator interaction on different phases of mechanical breath in pressure support ventilation

Introdução: O principal objetivo da ventilação mecânica é a diminuição do trabalho respiratório. Para que isto ocorra, o ciclo mecânico deveria coincidir com o tempo inspiratório neural do paciente. A assincronia paciente ventilador ocorre por fatores relacionados ao paciente e aos parâmetros ventilatórios e podem prolongar o tempo de suporte mecânico e permanência em unidades de terapia intensiva. Objetivos: Revisar a assincronia nas diferentes fases do ciclo respiratório, sua avaliação através dos gráficos e as intervenções capazes de melhorar a interação paciente ventilador em ventilação por pressão de suporte. Resultados/ Discussão: Através de busca em base de dados científicos, foram incluídos 26 artigos que abordavam o tema proposto. Os diferentes tipos de assincronia podem ser observados através de esforços ineficientes, atrasos no disparo, disparos automáticos, disparos duplos, presença de PEEP intrínseca, términos prematuro ou prolongado da inspiração e curvas diferentes do padrão usual. Conclusão: A correta identificação e ajustes conforme a demanda do paciente são pontos importantes na interação paciente ventilador e podem contribuir para a melhora do prognóstico destes pacientes.(AU)

Introduction: The main reason of mechanical ventilation is the decrease the work of breathing. To achieve it, the mechanical breath should coincide with the neural inspiratory time. Patient-ventilator asynchrony may be secondary for the facts related to the patient´s condition or ventilatory settings and may prolong support and UTI stay. Objectives: Review asynchrony in different phases of mechanical breath, the evaluation through ventilator waveforms and the proper settings to improve patient-ventilator interaction in pressure support ventilation. Results/ Discussion: Through research on scientific basis, 26 studies that match the theme were included. Asynchrony may be seen as inefficient efforts, trigger delay, auto-triggering, double triggering, presence of auto-PEEP, premature termination, delayed termination or unusual waveforms. Conclusion: Proper identification and adjustments that coincides with patient´s demand are critical points in patient ventilator interaction and may contribute to improve their prognosis.(AU)

Eficacia de la tinción de gram de muestras respiratorias para la predicción de la neumonía asociada al respirador, y su utilidad en la selección de la terapéutica antibiótica empírica / Effectiveness of the tinción of gram of respiratory samples for the prediction of the pneumonia associated to the respirator, and its utility in the selection of the therapeutic empirical antibiotic

Introducción. La neumonía asociada a la ventilación (NAV) es una complicación frecuente de la (VM) y se asocia a alta mortalidad. Su adecuado manejo se basa en detección precoz y terapia con antibióticos (ATB) empirica eficaz, siendo esenciales los métodos que permitan predecir la NAV y ayuden a seleccionar los ATB. Objetivo. Valorar la eficacia del exámen directo por tinción de Gram de muestras obtenidas del tracto respiratorio en la detección de NAV y como ayuda a la selección ATB. Material y Métodos. Se incluyeron prospectivamente 95 episodios de sospecha de NAV en 69 pacientes, considerando sólo los casos sin modificación ATB por más de 48hs o sin ATB. Las muestras fueron obtenidas por medio de lavado bronquioloalveolar a través de Fibrobroncoscopia (BAL) o miniBal por catéter envainado, a ciegas (miniBal). La confirmación se efectuó por el análisis bacteriológico cuantitativo (>10(4) y > 10(3) para el Bal y miniBal). Se calculó la sensibilidad (S), especificidad (E), valor predictivo positivo (VPP) y negativo (VPN) de la técnica de tinción directa de Gram, considerando como referencia el resultado microbiológico del cultivo del BAL o miniBal. Se comparó además la concordancia entre el tipo de germen observado en la tinción directa de Gram, bacilo Gram negativo (BGN) o coco Gram positivo (CGP) y el tipo de bacteria aislada en el cultivo. Se analizaron tambien las variables predictivas específicas o cualitativas, esto es la eficacia del Gram en predecir VAP po CGP o por BGN. Resultados. Se diagnosticó NAV en 52 casos. La S de la tinción de Gram fue de 60%, E: 100%, VPP Positivo: 100%, VPN: 67%. En cuanto a la eficacia para predecir NAV por BGN se observó: S: 52%, E: 100%, VPP: 100%, VPN: 72%. Para CGP: S: 91%, E: 100%, VPP 100% y VPN: 99%. Conclusión. Si bien un examen bacteriológico directo con tinción de Gram predice presencia de NAV, su VPN es bajo por lo que un directo negativo no implica ausencia de NAV. Sin embargo si ese examen....

Eficacia de la tinción de Gram de muestras respiratorias para la predicción de la neumonía asociada al respirador y su utilidad en la selección de la terapéutica antibiótica empírica / Efficacy of the Gram stain in respiratory samples for the prediction of ventilation associated pneumonia and its utility in the selection of the initial empiric antibiotic therapy

Introducción: La neumonía asociada a la ventilación (NAV) es una complicación frecuente de la ventilación mecánica (VM) y se asocia a alta mortalidad. Su adecuado manejo se basa en detección precoz y terapia con antibióticos (ATB) empírica eficaz, siendo esenciales los métodos que permitan predecir la NAV y ayuden a seleccionar los ATB. Objetivo: valorar la eficacia del examen directo por tinción de Gram de muestras obtenidas del tracto respiratorio en la detección de NAV y como ayuda a la selección de ATB. Materiales y Métodos: Se incluyeron prospectivamente 95 episodios de sospecha de NAV en 69 pacientes, considerando sólo los casos sin modificación de los ATB por más de 48 hs o sin ATB. Las muestras fueron obtenidas por medio de Lavado bronquioloalveolar a través de Fibro- broncoscopia (BAL) o minibal por catéter envainado a ciegas (miniBal). La confirmación se efectuó por el análisis bacteriológico cuantitativo (> 10 elevado a la cuarta y > 10³ para el BAL y minibal respectivamente). Se calculó la sensibilidad (S), especificidad (E), valor predictivo positivo (VPP) y negativo (VPN) de la técnica de tinción directa de Gram, considerando como referencia el resultado microbiológico del cultivo del BAL o mini-BAL. Se comparó además la concordancia entre el tipo de germen observado en la tinción directa de Gram, bacilo Gram negativo (BGN) o coco Gram positivo (CGP) y el tipo de bacteria aislada en el cultivo. Se analizaron también las variables predictivas específicas o cualitativas, esto es la eficacia del Gram en predecir VAP por CGP o por BGN. Resultados: Se diagnosticó NAV en 52 casos. La S de la tinción de Gram fue de 60%, E: 100%, VPP Positivo: 100%, VPN: 67%. En cuanto a la eficacia para predecir VAP por BGN se observó: S: 52%, E: 100%, VPP: 100%, VPN: 72%. Para CGP: s: 91 %, E: 100%, VPP 100% y VPN: 99%. Conclusión: Si bien un examen bacteriológico directo por tinción de Gram predice presencia de VAP, su VPN es bajo por lo que un directo negativo...

Introduction: Ventilator Associated Pneumonia (VAP) is a frequent complication in mechanically ventilated patients, and is associated with a high mortality. Early diagnosis and appropriate use of empiric antibiotic therapy (ATB) is essential to its treatment. Tests that help to make an early diagnosis and select the initial ATB are useful. Objective: to evaluate the accuracy of the Gram stain examination of respiratory tract samples in the prediction of VAP and its potential role in the selection of empiric ATB. Materials and methods: prospective evaluation of 95 episodes in 69 patients with clinical suspicion of VAP who had not had any changes in the ATB for more than 48 hours or had not been treated with ATB. Samples were taken by bronchoalveolar lavage (BAL) through flexible bronchoscopy or blind mini bronchoalveolar lavage with protected catheter. VAP was confirmed when the quantitative cultures showed =10 to the fourth ufc/ml for BAL and =10³ ufc/ml for mini BAL. A comparison was made between the type of bacteria observed by the direct Gram staining (Gram negative bacteria or Gram positive bacteria) and the type of bacteria isolated by culture. Specific or qualitative predictive variables were analyzed to determine the value of Gram staining to predict a Gram-negative VAP or Gram-positive VAP. Results: VAP was confirmed in 52 cases. The sensitivity of the Gram stain for VAP was 60%, specificity 100%; positive predictive value: 100% and negative predictive value: 67%. The sensitivity of Gram negative bacteria for VAP was: 52%; specificity: 100%; positive predictive value: 100%; negative predictive value: 72%. The sensitivity of Gram positive bacteria for VAP was: 91 %; specificity: 100%; positive predictive value: 100%; negative predictive value: 99%. Conclusions: A positive finding in the Gram staining examination of respiratory tract samples was highly predictive of VAP but a negative result did not mean absence of VAP, because the negative...

Resistencia antimicrobiana en la neumonía asociada al ventilador / Antimicrobial resistance in ventilator associated pneumonia

Se realizó un estudio descriptivo transversal para conocer el comportamiento de la resistencia antimicrobiana en la neumonía asociada al ventilador en la Unidad de Cuidados Intensivos del Hospital Clínico Quirúrgico Docente Amalia Simoni de la provincia de Camagüey. El universo estuvo representado por la totalidad de pacientes con neumonía nosocomial relacionada con la ventilación en el período comprendido entre enero de 2002 a diciembre de 2004. Para la determinación de la sensibilidad los cultivos fueron procesados por la técnica de Baver-Kirby. Los microorganismos más frecuentes en la investigación fueron el Acinetobacter y el Enterobacter spp., siendo la Tetraciclina (12.8 por ciento) y el Azlocillín (0.3 por ciento) los antimicrobianos de mayor y menor resistencia, respectivamente. La Gentamicina constituyó el antimicrobiano más resistente a los diferentes gérmenes

Sinusitis nosocomial en terapia intensiva / Nosocomial sinusitis in intensive care

La fiebre sin foco clínico aparente es un cuadro frecuente el el paciente crítico. Dentro de las probables causas, debe considerarse a la infección de los senos paranasales como causa de fiebre de origen desconocido en pacientes con ventilación mecánica. La incidencia global de sinusitis nosocomial es muy variable (0-100%) y se encuentra determinada por la población estudiada y el criterio diagnóstico utilizado para definirla. La SN se desarrolla a partir de una sumatoria de factores de riesgo, y parece no ser uno más importante que el otro de acuerdo a nuestra experiencia. Para su diagnóstico es fundamental discernir entre sinusitis radiológica mediante tomografía, de sinusitis infecciosa mediante la toma de muestra por punción-aspiración de los senos paranasales con cultivo positivo y presencia de reacción inflamatoria en el examen directo. Los microorganismos más comúnmente involucrados son los bacilos gramnegativos. Dentro de las complicaciones, la más común es la neumonía, no hallada en nuestra serie de pacientes. No existe un consenso en relación al tratamiento, pero sí recomendaciones sugeridas.

Risk factors associated with development of ventilator associated pneummonia

To assess the risk factors associated with development of ventilator associated pneumonia [VAP]. A case control study. Intensive Care Unit [ICU] at the Aga Khan University Hospital, Karachi, between January 1999 and June 2000. All patients with assisted mechanical ventilation were assessed for the development of VAP. Risk factors associated with development of VAP were determined. Adult patients who developed pneumonia, 48 hours after ventilation, were called cases while those who did not develop pneumonia were called controls. Seventy [28%] out of 250 mechanically ventilated patients developed VAP [rate of VAP was 26 cases per 1000 ventilator days]. Shock during first 48 hours of ventilation [odds ratio [OR], 5.95; 95% confidence interval [CI], 2.83-12.52], transport out of ICU during mechanical ventilation [OR, 6.0; 95% CI, 2.92-12.37], re-intubation [OR, 4.23; 95% CI, 2.53-9.85], prior episode of aspiration of gastric content [OR, 3.07; 95% CI, 1.35-7.01], and use of antibiotics prior to intubation [OR,2.55; 95% CI, 1.20-5.41] were found to be independently associated with a higher risk of developing VAP. Gram negative organisms and Staphylococcus aureus were responsible for over 90% of cases. Patients with VAP had higher crude mortality rate [57.1%] compared with controls [32.2%]. Ventilator associated pneumonia is associated with a high mortality. This study has identified risk factors associated with VAP

Controle automático da ventilação mecânica para minimizar a lesão pulmonar induzida pela ventilação / Automatic control of the mechanical ventilation for minimizing the ventilation induced lung injury

O ajuste de parâmetros dos ventiladores mecânicos pulmonares para evitar a reabertura cíclica de unidades alveolares e pequenas vias aéreas, assim como a hiperdistensão dos septos alveolares, tem sido motivo de atenção nos últimos anos. Este trabalho utiliza um modelo de lesão pulmonar aguda (ALI) em suínos para testar um controlador de ventiladores em malha fechada baseado em regras e modelos discutidos na literatura. Utiliza-se um modelo polinomial da cursa pressão-volume do sistema respiratório para o ajuste da pressão positiva ao final da expiração (PEEP), visando evitar a reabertura cíclica de unidades alveolares, e o ajuste do volume corrente, visando evitar a hiperdistensão pulmonar. Um índice de hiperdistensão baseado na identificação de uma elastância não linear para o sistema respiratório permite o uso do controlador com qualquer forma de onda de ventilação constrolada. Os resultados do controlador proposto foram confrontados com resultados obtidos na ventilação de um grupo controle, manualmente ventilados com base nas mesmas premissas. Como resultado, o controlador automático obteve valores de PEEP dentro da faixa de valores obtidos no grupo controle, porém com menor dispersão. O índice de hiperdistensão calculado ficou abaixo do limiar de hiperdistensão em 5 dos 6 animais do grupo ventilado automaticamente, e em 3 dos 6 animais ventilados do grupo controle. O controlador se comportou de forma estável e os resultados recomendam seu uso em ALI.

Ventilator-associated pneumonia in a newborn intensive care unit.

A prospective observational study was conducted in a neonatal intensive care unit to identify factors associated with the development of ventilator-associated pneumonia (VAP) in 170 infants aged less than 30 days who required mechanical ventilation for longer than 48 hours. VAP occurred in 85 infants (50 cases per 100 mechanically-ventilated infants) or 70.3 cases per 1,000 ventilator days. Stepwise logistic regression analysis identified 3 factors independently associated with VAP: umbilical catheterization [adjusted odds ratio (AOR)=2.5; 95% confidence interval (CI)=1.3 to 4.7; p=0.007]; respiratory distress syndrome (AOR=2.0; 95% CI=1.0 to 3.9; p=0.03); and insertion of orogastric tube (AOR=3.0; 95% CI=1.3 to 7.2; p=0.01). Infants with VAP had longer duration on ventilator (14.2 days vs 5.9 days; p<0.001) and longer hospital stay (28.2 days vs 13.8 days; p<0.001). Organisms were isolated in 42 specimens (49.4%) from endotracheal aspirate culture and in 17 specimens (20.0%) from hemoculture; Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter spp were predominant. Polymicrobial infection was found in 11 specimens (12.9%) from endotracheal aspirate culture. Leukocytosis and blood gas values could not predict the presence of VAP. The mortality of infants with VAP (29.4%) did not differ significantly from that of infants without VAP (30.6%) (p=0.87). Certain clinical interventions might potentially affect the incidence of VAP and outcome associated with VAP.

Neumonía asociada a ventilación mecánica: enfoque actual / Pneumonia associated with mechanical ventilation: current approach

La neumonía asociada a la ventilación mecánica (NAVM) es la complicación infecciosa más importante que afecta a los pacientes conectados a ventilación mecánica con una mortalidad que fluctúa entre 30 a 70 por ciento. La falta de especificidad del diagnóstico clínico puede inducir a un sobretratamiento de la NAVM, de modo que es imprescindible la toma de muestras respiratorias para cultivo y que éste debe ser cuantitativo, resultados por debajo de los límites sugeridos no descartan necesariamente el diagnóstico pero lo hacen menos probable y permite ajustar el tratamiento antibiótico e incluso acortar los plazos de antibioterapia. Muchos factores han sido asociados a una mayor mortalidad de la NAVM, no obstante, el tratamiento antibiótico inadecuado y el retraso en su inicio son los únicos factores que pueden ser modificados para reducir su mortalidad. El tratamiento antibiótico debe ser empírico y tradicionalmente se basa en los días de ventilación mecánica, considerándola precoz si ocurre los primeros cuatro días. Este enfoque puede ocasionar hasta 30 por ciento de tratamientos antibióticos inadecuados. Por este motivo se ha introducido el concepto de terapia de desescalamiento que implica un esquema antibiótico empírico de amplio espectro que se ajusta posteriormente de acuerdo a los hallazgos microbiológicos.