Luiz Marcelo Sá Malbouisson

Assessment of PEEP-induced reopening of collapsed lung regions in acute lung injury: are one or three CT sections representative of the entire lung?

Abstract.Objectives: To study whether PEEP-induced reopening of collapsed lung regions – defined as the decrease in nonaerated lung volume measured on a single or three computerized tomographic (CT) sections – is representative of the decrease in overall nonaerated lung volume. Design: Review of 39 CT scans obtained in consecutive patients with Acute Lung Injury. Settings: Fourteen-bed surgical intensive care unit of a University Hospital. Measurements and results: PEEP-induced decrease in nonaerated lung volume was measured in 39 patients with ALI on a single juxtadiaphragmatic CT section, on three CT sections – apical, hilar, and juxtadiaphragmatic – and on contiguous apex-to-diaphragm CT sections. The percentage of decrease in nonaerated lung volume following PEEP, was compared between one, three and all CT sections using a linear regression analysis and Bland and Altmans method. The decrease in nonaerated lung volume measured on a single and three CT sections was significantly correlated with the decrease in nonaerated lung volume measured on all CT sections: R=0.83, P<0.0001 for one CT section and R=0.92, P<0.0001 for three CT sections. However, measurements performed on a single CT section were poorly representative of the overall lung: bias –6%, limits of agreement ranging between –37% and +25%. Measurements performed on three CT sections overestimated by 11% the overall decrease in nonaerated lung volume: bias –11%, limits of agreement ranging between –29% and +7%. Conclusions: PEEP-induced reopening of collapsed lung regions measured on a single or three CT sections sensibly differs from the reopening of collapsed lung regions measured on the overall lung. The inhomogeneous distribution of PEEP-induced reopening of collapsed lung regions along the cephalocaudal axis probably explains these discrepancies.

Terlipressin versus Norepinephrine in the Treatment of Hepatorenal Syndrome: A Systematic Review and Meta-Analysis

Background Hepatorenal syndrome (HRS) is a severe and progressive functional renal failure occurring in patients with cirrhosis and ascites. Terlipressin is recognized as an effective treatment of HRS, but it is expensive and not widely available. Norepinephrine could be an effective alternative. This systematic review and meta-analysis aimed to evaluate the efficacy and safety of norepinephrine compared to terlipressin in the management of HRS. Methods We searched the Medline, Embase, Scopus, CENTRAL, Lilacs and Scielo databases for randomized trials of norepinephrine and terlipressin in the treatment of HRS up to January 2014. Two reviewers collected data and assessed the outcomes and risk of bias. The primary outcome was the reversal of HRS. Secondary outcomes were mortality, recurrence of HRS and adverse events. Results Four studies comprising 154 patients were included. All trials were considered to be at overall high risk of bias. There was no difference in the reversal of HRS (RR = 0.97, 95% CI = 0.76 to 1.23), mortality at 30 days (RR = 0.89, 95% CI = 0.68 to 1.17) and recurrence of HRS (RR = 0.72; 95% CI = 0.36 to 1.45) between norepinephrine and terlipressin. Adverse events were less common with norepinephrine (RR = 0.36, 95% CI = 0.15 to 0.83). Conclusions Norepinephrine seems to be an attractive alternative to terlipressin in the treatment of HRS and is associated with less adverse events. However, these findings are based on data extracted from only four small studies.

The effect of excess fluid balance on the mortality rate of surgical patients: a multicenter prospective study

IntroductionIn some studies including small populations of patients undergoing specific surgery, an intraoperative liberal infusion of fluids was associated with increasing morbidity when compared to restrictive strategies. Therefore, to evaluate the role of excessive fluid infusion in a general population with high-risk surgery is very important. The aim of this study was to evaluate the impact of intraoperative fluid balance on the postoperative organ dysfunction, infection and mortality rate.MethodsWe conducted a prospective cohort study during one year in four ICUs from three tertiary hospitals, which included patients aged 18 years or more who required postoperative ICU after undergoing major surgery. Patients who underwent palliative surgery and whose fluid balance could change in outcome were excluded. The calculation of fluid balance was based on preoperative fasting, insensible losses from surgeries and urine output minus fluid replacement intraoperatively.ResultsThe study included 479 patients. Mean age was 61.2 ± 17.0 years and 8.8% of patients died at the hospital during the study. The median duration of surgery was 4.0 (3.2 to 5.5) h and the value of the Simplified Acute Physiology Score (SAPS) 3 score was 41.8 ± 14.5. Comparing survivors and non-survivors, the intraoperative fluid balance from non-survivors was higher (1,950 (1,400 to 3,400) mL vs. 1,400 (1,000 to 1,600) mL, P <0.001). Patients with fluid balance above 2,000 mL intraoperatively had a longer ICU stay (4.0 (3.0 to 8.0) vs. 3.0 (2.0 to 6.0), P <0.001) and higher incidence of infectious (41.9% vs. 25.9%, P = 0.001), neurological (46.2% vs. 13.2%, P <0.001), cardiovascular (63.2% vs. 39.6%, P <0.001) and respiratory complications (34.3% vs. 11.6%, P <0.001). In multivariate analysis, the fluid balance was an independent factor for death (OR per 100 mL = 1.024; P = 0.006; 95% CI 1.007 to 1.041).ConclusionsPatients with excessive intraoperative fluid balance have more ICU complications and higher hospital mortality.

Recomendações brasileiras de ventilação mecânica 2013. Parte I

Perspectives on invasive and noninvasive ventilatory support for critically ill patients are evolving, as much evidence indicates that ventilation may have positive effects on patient survival and the quality of the care provided in intensive care units in Brazil. For those reasons, the Brazilian Association of Intensive Care Medicine (Associacao de Medicina Intensiva Brasileira - AMIB) and the Brazilian Thoracic Society (Sociedade Brasileira de Pneumologia e Tisiologia - SBPT), represented by the Mechanical Ventilation Committee and the Commission of Intensive Therapy, respectively, decided to review the literature and draft recommendations for mechanical ventilation with the goal of creating a document for bedside guidance as to the best practices on mechanical ventilation available to their members. The document was based on the available evidence regarding 29 subtopics selected as the most relevant for the subject of interest. The project was developed in several stages, during which the selected topics were distributed among experts recommended by both societies with recent publications on the subject of interest and/or significant teaching and research activity in the field of mechanical ventilation in Brazil. The experts were divided into pairs that were charged with performing a thorough review of the international literature on each topic. All the experts met at the Forum on Mechanical Ventilation, which was held at the headquarters of AMIB in Sao Paulo on August 3 and 4, 2013, to collaboratively draft the final text corresponding to each sub-topic, which was presented to, appraised, discussed and approved in a plenary session that included all 58 participants and aimed to create the final document.

The effects of positive end-expiratory pressure on respiratory system mechanics and hemodynamics in postoperative cardiac surgery patients

We prospectively evaluated the effects of positive end-expiratory pressure (PEEP) on the respiratory mechanical properties and hemodynamics of 10 postoperative adult cardiac patients undergoing mechanical ventilation while still anesthetized and paralyzed. The respiratory mechanics was evaluated by the inflation inspiratory occlusion method and hemodynamics by conventional methods. Each patient was randomized to a different level of PEEP (5, 10 and 15 cmH2O), while zero end-expiratory pressure (ZEEP) was established as control. PEEP of 15-min duration was applied at 20-min intervals. The frequency dependence of resistance and the viscoelastic properties and elastance of the respiratory system were evaluated together with hemodynamic and respiratory indexes. We observed a significant decrease in total airway resistance (13.12 +/- 0.79 cmH2O l-1 s-1 at ZEEP, 11.94 +/- 0.55 cmH2O l-1 s-1 (P<0.0197) at 5 cmH2O of PEEP, 11.42 +/- 0.71 cmH2O l-1 s-1 (P<0.0255) at 10 cmH2O of PEEP, and 10.32 +/- 0.57 cmH2O l-1 s-1 (P<0.0002) at 15 cmH2O of PEEP). The elastance (Ers; cmH2O/l) was not significantly modified by PEEP from zero (23.49 +/- 1.21) to 5 cmH2O (21.89 +/- 0.70). However, a significant decrease (P<0.0003) at 10 cmH2O PEEP (18.86 +/- 1.13), as well as (P<0.0001) at 15 cmH2O (18.41 +/- 0.82) was observed after PEEP application. Volume dependence of viscoelastic properties showed a slight but not significant tendency to increase with PEEP. The significant decreases in cardiac index (l min-1 m-2) due to PEEP increments (3.90 +/- 0.22 at ZEEP, 3.43 +/- 0.17 (P<0. 0260) at 5 cmH2O of PEEP, 3.31 +/- 0.22 (P<0.0260) at 10 cmH2O of PEEP, and 3.10 +/- 0.22 (P<0.0113) at 15 cmH2O of PEEP) were compensated for by an increase in arterial oxygen content owing to shunt fraction reduction (%) from 22.26 +/- 2.28 at ZEEP to 11.66 +/- 1.24 at PEEP of 15 cmH2O (P<0.0007). We conclude that increments in PEEP resulted in a reduction of both airway resistance and respiratory elastance. These results could reflect improvement in respiratory mechanics. However, due to possible hemodynamic instability, PEEP should be carefully applied to postoperative cardiac patients.

Aplicabilidade do escore fisiológico agudo simplificado (SAPS 3) em hospitais brasileiros

JUSTIFICATIVA E OBJETIVOS: O sistema prognostico SAPS 3 (Simplified Acute Physiology Score 3) e composto de 20 variaveis, representadas por escore fisiologico agudo e avaliacao do estado previo, visando estabelecer indice preditivo de mortalidade para pacientes admitidos em unidades de terapia intensiva (UTI). O estudo teve objetivo de validar este sistema e verificar o poder discriminatorio deste indice em pacientes cirurgicos do Brasil. METODO: Estudo prospectivo, realizado em duas UTI especializadas em pacientes cirurgicos de dois diferentes hospitais, no periodo de um ano, excluiuse pacientes com idade inferior a 16 anos, que permaneceram tempo inferior a 24 horas na UTI, readmitidos e aqueles admitidos para procedimento dialitico. A habilidade preditiva do indice SAPS 3 em diferenciar sobreviventes e nao sobreviventes foi verificada utilizando curva ROC e a calibracao pelo teste Hosmer-Lemeshow goodness-of-fit. RESULTADOS: Foram incluidos no estudo 1.310 pacientes. Operacoes gastrintestinais foram predominantes (34,9%). O menor valor do indice SAPS 3 foi 18 e o maior 154, media de 48,5 ± 18,1. A mortalidade hospitalar prevista e real foi de 10,3% e de 10,8%, respectivamente, razao de mortalidade padronizada (SMR) foi 1,04 (IC95% = 1,03-1,07). A calibracao pelo metodo Hosmer e Lemeshow mostrou X2 = 10,47 p = 0,234. O valor do escore SAPS 3 que melhor discriminou sobreviventes e nao sobreviventes foi 57, com sensibilidade de 75,8% e especificidade de 86%. Dos pacientes com indice SAPS 3 maior que 57, 73,5% nao sobreviveram versus 26,5% de sobreviventes (OR = 1,32 IC95% 1,23 - 1,42, p < 0,0001). CONCLUSOES: O sistema SAPS 3 e valido na populacao brasileira de pacientes cirurgicos, sendo util para indicar pacientes graves e determinar maiores cuidados neste grupo.

Applicability of the simplified acute physiology score (SAPS 3) in brazilian hospitals

BACKGROUND AND OBJECTIVES The SAPS 3 (Simplified Acute Physiology Score 3) prognostic system is composed of 20 parameters, represented by an acute physiology score and assessment of the previous status, aimed at establishing a predictive mortality index for patients admitted to intensive care units (ICU). The objective of this study was to validate this system and determine its discriminatory power in surgical patients in Brazil. METHODS This is a prospective study undertaken in two surgical ICUs of two different hospitals over a one-year period; patients younger than 16 years, who stay at the ICU for less than 24 hours, readmitted to the unit, and those admitted for dialysis were excluded from the study. The predictive ability of the SAPS 3 index to differentiate survivors and non-survivors was determined by the ROC curve and calibration by the Hosmer-Lemeshow goodness-of-fit test. RESULTS One thousand three-hundred and ten patients were included in the study. Gastrointestinal surgeries predominated (34.9%). Eighteen was the lower SAPS 3 index and the highest was 154, with a mean of 48.5 +/- 18.1. The predicted and real hospital mortality was 10.3% and 10.8%, respectively; the standardized mortality ratio (SMR) was 1.04 (95%CI = 1.03-1.07). Calibration by the Hosmer and Lemeshow method showed X(2) = 10.47 p = 0.234. The SAPS 3 score that better discriminated survivors and non-survivors was 57, with sensitivity of 75.8% and specificity 86%. Among the patients with SAPS 3 index higher than 57, 73.5% did not survive versus 26.5% who survived (OR= 1.32, 95%CI 1.23-1.42, p < 0.0001). CONCLUSIONS The SAPS 3 system is valid for the Brazilian population of surgical patients, being a useful indicator of critical patients and to determine greater care in this group.

Atelectasis during anesthesia: pathophysiology and treatment

JUSTIFICATIVA Y OBJETIVOS: El colapso pulmonar intraoperatorio es una complicacion de elevada incidencia en pacientes sometidos a la intervencion quirurgica bajo anestesia general con relajamiento/paralisis de la musculatura. Esta complicacion esta asociada al empeoramiento de los cambios de gas en el intraoperatorio y en algunos casos, necesidad de soporte respiratorio prolongado en el periodo postoperatorio. Los objetivos de este estudio fueron los de revisar los aspectos fisiopatologicos de la formacion de atelectasias durante anestesia general y las posibles maniobras terapeuticas para prevenir y tratar esa complicacion. CONTENIDO: En esta revision, los conceptos sobre la incidencia de atelectasias intraoperatorias, los factores relacionados a su desarrollo, tanto mecanicos como los relacionados al ajuste del respirador durante el procedimiento quirurgico, los aspectos del diagnostico y las estrategias de prevencion y tratamiento fueron abordados de manera sistematica. CONCLUSIONES: La comprension de los mecanismos relacionados al desarrollo del colapso pulmonar durante el periodo intraoperatorio, como tambien su tratamiento, pueden contribuir para la reduccion de la incidencia de complicaciones pulmonares postoperatorias, el tiempo de recuperacion y los costes de las internaciones en los hospitales.BACKGROUND AND METHODS The incidence of intraoperative pulmonary collapse is elevated in patients undergoing surgery under general anesthesia with muscle relaxation/paralysis. This complication is associated with worsening intraoperative gas exchange and, in some cases, the need for prolonged postoperative respiratory support. The objective of this report was to review the pathophysiological aspects of atelectasis during general anesthesia and possible therapeutic maneuvers that could prevent and treat this complication. CONTENTS This review discusses the concepts about the incidence of intraoperative atelectasis, factors that influence their development, both mechanical and those related to mechanical ventilator settings during the surgery, diagnostic criteria, and strategies to prevent and treat this complication. CONCLUSIONS Understanding of the mechanisms related with the development of intraoperative pulmonary collapse, as well as its treatment, can contribute to reduce the incidence of postoperative pulmonary complications, the length of recovery and hospital costs.

Hypoxemia after myocardial revascularization: analysis of risk factors

JUSTIFICATIVA E OBJETIVOS: Hipoxemia grave e uma complicacao frequente no pos-operatorio imediato de revascularizacao do miocardio (RM), promovendo aumento da duracao da ventilacao mecânica, da incidencia de infeccoes pulmonares, dos custos e da mortalidade. O objetivo desse estudo foi identificar fatores preditivos de hipoxemia grave em pacientes submetidos a RM. METODO: Foram estudados 481 pacientes adultos submetidos a RM eletiva entre outubro de 2003 e marco de 2004. Considerou-se hipoxemia grave uma relacao PaO2/FiO2 0,2 para exclusao da variavel do modelo de RL e p < 0,1 como sendo significativo. RESULTADOS: O tempo para extubacao dos pacientes com hipoxemia grave foi maior que nos outros pacientes (p < 0,001). Na analise multivariada, as variaveis idade (p = 0,081), peso (p = 0,001), necessidade de CEC prolongada (p = 0,033) e disfuncao ventricular esquerda (p = 0,082) foram identificadas como preditores independentes para hipoxemia grave. CONCLUSOES: Pacientes com idade e peso elevados, disfuncao ventricular esquerda e necessidade de CEC apresentaram risco aumentado para hipoxemia grave apos RM. Nesses pacientes, o uso de estrategias ventilatorias perioperatoria com pressoes positivas expiratorias mais elevadas e manobra de recrutamento alveolar devem ser consideradas tendo como objetivo a prevencao da disfuncao pulmonar pos-operatoria.BACKGROUND AND OBJECTIVES Severe hypoxemia is complication frequently seen in the immediate postoperative period of myocardial revascularization (MR), increasing the duration of mechanical ventilation, the incidence of pulmonary infections, hospital costs, and mortality. The objective of this study was to identify predictive factors of severe hypoxemia in patients undergoing MR. METHODS Four-hundred and eighty-one adult patients undergoing elective MR between October 2003 and March 2004 were enrolled in this study. Severe hypoxemia was defined as PaO2/FiO2 < 150 upon admission to the ICU. The Chi-square test, Students t or Wilcoxon test, followed by multivariate analysis and logistic regression (LR) for parameters with p < 0.25 in the univariate analysis, were used for the statistical analysis. A p > 0.2 was required to exclude the parameter from the LR model, and a p < 0.1 was considered significant. RESULTS Time for extubation was greater in patients with severe hypoxemia (p < 0.001). Multivariate analysis identified age (p = 0.081), weight (p = 0.001), need of prolonged CBP (p = 0.033), and left ventricular dysfunction (p = 0.082) as independent predictors of severe hypoxemia. CONCLUSIONS Older and overweighted patients, those with left ventricular dysfunction, and those who needed CPB presented an increased risk of severe hypoxemia after MR. In those patients, the use of perioperative ventilatory strategies, with elevated positive expiratory pressures and alveolar recruitment maneuver should be considered to prevent postoperative pulmonary dysfunction.

Hipoxemia após revascularização miocárdica: análise dos fatores de risco

JUSTIFICATIVA E OBJETIVOS: Hipoxemia grave e uma complicacao frequente no pos-operatorio imediato de revascularizacao do miocardio (RM), promovendo aumento da duracao da ventilacao mecânica, da incidencia de infeccoes pulmonares, dos custos e da mortalidade. O objetivo desse estudo foi identificar fatores preditivos de hipoxemia grave em pacientes submetidos a RM. METODO: Foram estudados 481 pacientes adultos submetidos a RM eletiva entre outubro de 2003 e marco de 2004. Considerou-se hipoxemia grave uma relacao PaO2/FiO2 0,2 para exclusao da variavel do modelo de RL e p < 0,1 como sendo significativo. RESULTADOS: O tempo para extubacao dos pacientes com hipoxemia grave foi maior que nos outros pacientes (p < 0,001). Na analise multivariada, as variaveis idade (p = 0,081), peso (p = 0,001), necessidade de CEC prolongada (p = 0,033) e disfuncao ventricular esquerda (p = 0,082) foram identificadas como preditores independentes para hipoxemia grave. CONCLUSOES: Pacientes com idade e peso elevados, disfuncao ventricular esquerda e necessidade de CEC apresentaram risco aumentado para hipoxemia grave apos RM. Nesses pacientes, o uso de estrategias ventilatorias perioperatoria com pressoes positivas expiratorias mais elevadas e manobra de recrutamento alveolar devem ser consideradas tendo como objetivo a prevencao da disfuncao pulmonar pos-operatoria.BACKGROUND AND OBJECTIVES Severe hypoxemia is complication frequently seen in the immediate postoperative period of myocardial revascularization (MR), increasing the duration of mechanical ventilation, the incidence of pulmonary infections, hospital costs, and mortality. The objective of this study was to identify predictive factors of severe hypoxemia in patients undergoing MR. METHODS Four-hundred and eighty-one adult patients undergoing elective MR between October 2003 and March 2004 were enrolled in this study. Severe hypoxemia was defined as PaO2/FiO2 < 150 upon admission to the ICU. The Chi-square test, Students t or Wilcoxon test, followed by multivariate analysis and logistic regression (LR) for parameters with p < 0.25 in the univariate analysis, were used for the statistical analysis. A p > 0.2 was required to exclude the parameter from the LR model, and a p < 0.1 was considered significant. RESULTS Time for extubation was greater in patients with severe hypoxemia (p < 0.001). Multivariate analysis identified age (p = 0.081), weight (p = 0.001), need of prolonged CBP (p = 0.033), and left ventricular dysfunction (p = 0.082) as independent predictors of severe hypoxemia. CONCLUSIONS Older and overweighted patients, those with left ventricular dysfunction, and those who needed CPB presented an increased risk of severe hypoxemia after MR. In those patients, the use of perioperative ventilatory strategies, with elevated positive expiratory pressures and alveolar recruitment maneuver should be considered to prevent postoperative pulmonary dysfunction.