Pedro Vitale Mendes

Extracorporeal membrane oxygenation for severe respiratory failure in adult patients: A systematic review and meta-analysis of current evidence

BACKGROUND Extracorporeal membrane oxygenation (ECMO) for acute respiratory failure is still a matter of debate. METHODS We performed a structured search on Pubmed, EMBASE, Lilacs, and the Cochrane Library for randomized controlled trials and observational case-control studies with severity-paired patients, evaluating the use of ECMO on severe acute respiratory failure in adult patients. A random-effect model using DerSimonian and Laird method for variance estimator was performed to evaluate the effect of ECMO use on hospital mortality. Heterogeneity between studies was assessed with Cochrans Q statistic and Higgins I(2). RESULTS Three studies were included on the metanalysis, comprising 353 patients in the main analysis, in which 179 patients were ECMO supported. One study was a randomized controlled trial and two were observational studies with a propensity score matching. The most common reason for acute respiratory failure was influenza H1N1 pneumonia (45%) and pneumonia (33%). ECMO was not associated with a reduction in hospital mortality (OR = 0.71; CI 95% = 0.34 - 1.47; P = 0.358). If alternative severity-pairing method presented by the two observational studies was included, a total of 478 cases were included, in which 228 received ECMO support. In the former analysis, ECMO had a benefit on hospital mortality (OR = 0.52; CI 95% = 0.35 - 0.76; P < 0.001). CONCLUSION Extracorporeal membrane oxygenation benefit on hospital mortality is unclear. Results were sensitive to statistical analysis, and no definitive conclusion can be drawn from the available data. More studies are needed before the widespread use of ECMO can be recommended.

Comparison between ultrasound- and bronchoscopy-guided percutaneous dilational tracheostomy in critically ill patients: a retrospective cohort study.

INTRODUCTION Percutaneous dilational tracheostomy (PDT) is routinely performed in the intensive care unit with bronchoscopic guidance. Recently, ultrasound (US) has emerged as a new safety adjunct tool to increase the efficacy of PDT. However, the available data are limited to case series without any control group. Hence, a retrospective cohort study was designed to evaluate the efficacy of US-guided PDT compared with bronchoscopy-guided PDT. METHODS All patients who were submitted to PDT after the standardization of US-guided PDT technique in our institution were analyzed. Demographic and procedure-related variables, complications, and clinical outcomes were collected and compared in patients undergoing US- or bronchoscopy-guided PDT. RESULTS Sixty patients who had been submitted to PDT were studied, including 11 under bronchoscopy guidance and 49 under US guidance. No surgical conversion was necessary in any of the procedures, and bronchoscopy assistance was only required in 1 case in the US group. The procedure length was shorter in the US group than in the bronchoscopy group (12 vs 15 minutes, P = .028). None of the patients had any major complications. The minor complication rates were not significantly different between the groups, nor was the probability of breathing without assistance within 28 days, intensive care unit length of stay, or hospital mortality. CONCLUSION Ultrasound-guided PDT is effective, safe, and associated with similar complication rates and clinical outcomes compared with bronchoscopy-guided PDT.

First-year experience of a Brazilian tertiary medical center in supporting severely ill patients using extracorporeal membrane oxygenation

OBJECTIVES: The aim of this manuscript is to describe the first year of our experience using extracorporeal membrane oxygenation support. METHODS: Ten patients with severe refractory hypoxemia, two with associated severe cardiovascular failure, were supported using venous-venous extracorporeal membrane oxygenation (eight patients) or veno-arterial extracorporeal membrane oxygenation (two patients). RESULTS: The median age of the patients was 31 yr (range 14–71 yr). Their median simplified acute physiological score three (SAPS3) was 94 (range 84–118), and they had a median expected mortality of 95% (range 87–99%). Community-acquired pneumonia was the most common diagnosis (50%), followed by P. jiroveci pneumonia in two patients with AIDS (20%). Six patients were transferred from other ICUs during extracorporeal membrane oxygenation support, three of whom were transferred between ICUs within the hospital (30%), two by ambulance (20%) and one by helicopter (10%). Only one patient (10%) was anticoagulated with heparin throughout extracorporeal membrane oxygenation support. Eighty percent of patients required continuous venous-venous hemofiltration. Three patients (30%) developed persistent hypoxemia, which was corrected using higher positive end-expiratory pressure, higher inspired oxygen fractions, recruitment maneuvers, and nitric oxide. The median time on extracorporeal membrane oxygenation support was five (range 3–32) days. The median length of the hospital stay was 31 (range 3-97) days. Four patients (40%) survived to 60 days, and they were free from renal replacement therapy and oxygen support. CONCLUSIONS: The use of extracorporeal membrane oxygenation support in severely ill patients is possible in the presence of a structured team. Efforts must be made to recognize the necessity of extracorporeal respiratory support at an early stage and to prompt activation of the extracorporeal membrane oxygenation team.

Severe hypoxemia during veno-venous extracorporeal membrane oxygenation: exploring the limits of extracorporeal respiratory support

OBJECTIVE: Veno-venous extracorporeal oxygenation for respiratory support has emerged as a rescue alternative for patients with hypoxemia. However, in some patients with more severe lung injury, extracorporeal support fails to restore arterial oxygenation. Based on four clinical vignettes, the aims of this article were to describe the pathophysiology of this concerning problem and to discuss possibilities for hypoxemia resolution. METHODS: Considering the main reasons and rationale for hypoxemia during veno-venous extracorporeal membrane oxygenation, some possible bedside solutions must be considered: 1) optimization of extracorporeal membrane oxygenation blood flow; 2) identification of recirculation and cannula repositioning if necessary; 3) optimization of residual lung function and consideration of blood transfusion; 4) diagnosis of oxygenator dysfunction and consideration of its replacement; and finally 5) optimization of the ratio of extracorporeal membrane oxygenation blood flow to cardiac output, based on the reduction of cardiac output. CONCLUSION: Therefore, based on the pathophysiology of hypoxemia during veno-venous extracorporeal oxygenation support, we propose a stepwise approach to help guide specific interventions.

Blood flow/pump rotation ratio as an artificial lung performance monitoring tool during extracorporeal respiratory support using centrifugal pumps.

Objective To analyze the correlations of the blood flow/pump rotation ratio and the transmembrane pressure, CO2 and O2 transfer during the extracorporeal respiratory support. Methods Five animals were instrumented and submitted to extracorporeal membrane oxygenation in a five-step protocol, including abdominal sepsis and lung injury. Results This study showed that blood flow/pump rotations ratio variations are dependent on extracorporeal membrane oxygenation blood flow in a positive logarithmic fashion. Blood flow/pump rotation ratio variations are negatively associated with transmembrane pressure (R2 = 0.5 for blood flow = 1500mL/minute and R2 = 0.4 for blood flow = 3500mL/minute, both with p < 0.001) and positively associated with CO2 transfer variations (R2 = 0.2 for sweep gas flow ≤ 6L/minute, p < 0.001, and R2 = 0.1 for sweep gas flow > 6L/minute, p = 0.006), and the blood flow/pump rotation ratio is not associated with O2 transfer variations (R2 = 0.01 for blood flow = 1500mL/minute, p = 0.19, and R2 = - 0.01 for blood flow = 3500 mL/minute, p = 0.46). Conclusion Blood flow/pump rotation ratio variation is negatively associated with transmembrane pressure and positively associated with CO2 transfer in this animal model. According to the clinical situation, a decrease in the blood flow/pump rotation ratio can indicate artificial lung dysfunction without the occurrence of hypoxemia.

The economic effect of extracorporeal membrane oxygenation to support adults with severe respiratory failure in Brazil: a hypothetical analysis.

Objective: To analyze the cost-utility of using extracorporeal oxygenation for patients with severe acute respiratory distress syndrome in Brazil. Methods: A decision tree was constructed using databases from previously published studies. Costs were taken from the average price paid by the Brazilian Unified Health System ( Sistema Unico de Saude; SUS) over three months in 2011. Using the data of 10,000,000 simulated patients with predetermined outcomes and costs, an analysis was performed of the ratio between cost increase and years of life gained, adjusted for quality (cost-utility), with survival rates of 40 and 60% for patients using extracorporeal membrane oxygenation. Results: The decision tree resulted in 16 outcomes with different life support techniques. With survival rates of 40 and 60%, respectively, the increased costs were R

Challenges in patients supported with extracorporeal membrane oxygenation in Brazil

=-301.00/-14.00, with a Part of a document submitted to the Brazilian Network for Health Technology Assessment (Rede Brasileira de Avaliacao de Tecnologias em Saude), Ministry of Health. ABSTRACT

Is There a Role for Balanced Solutions in Septic Patients

After the influenza A H1N1 epidemics, the use ofextracorporeal membrane oxygenation (ECMO) has increasedworldwide. The goal of respiratory ECMO support is toimprove hypoxemia and hypercapnia, allowing protectivemechanical ventilation to avoid further ventilator-associatedlung injury (1). The current literature supports improvedoutcomes using ECMO in severe lung injury patients. InBrazil, few hospitals are able to provide respiratory ECMOsupport, and there is no transfer system (2).The aim of this manuscript was to present and discusstwo cases of severe respiratory failure supported withECMO.

Ultrasound-guided percutaneous dilatational tracheostomy: Going deep into the sea

ABSTRACT The use of fluid bolus infusion is the cornerstone for hemodynamic resuscitation of critically ill patients. Recently, the clinical use of colloids has lost strength with the publication of several trials suggesting no benefit, and possible harm of its use. On the other hand, the so-called balanced solutions, with low chloride concentrations, have emerged as an alternative with potential physiological benefits over traditional saline solution. Normal saline carries a high amount of chloride which has been associated with an increased incidence of metabolic acidosis, renal vasoconstriction, and reduced urine output. Recent observational studies associated the use of saline with acute kidney injury, which was not observed in a single prospective randomized controlled trial. The present review summarizes available literature regarding the potential clinical and laboratorial benefits of balanced solutions in septic patients.

Early Versus Late Initiation of Renal Replacement Therapy in Critically Ill Patients: Systematic Review and Meta-Analysis.

We have read with greatinterest theletter from Dr. Yavuz regarding our paper. The author recently published a randomized clinical trial comparing ultrasound (US)-guided percutaneous dilatational tracheostomy (PDT) with the conventional landmark-based PDT; and in the letter, he makes an interesting comparison between the patients submitted to US-guided PDT in his trial [1] and ours [2]. The author still raises several questions we are pleased to provide answers. In our study, the procedures were performed according to standardized practices following hospital routines, available in supplemental materials published with the paper. So, as described in supplemental materials, “in ultrasound-guided PDT, a physician using aseptic technique determines the probable puncture site using anatomical landmarks. Sterile ultrasound is performed by an intensivist accompanied by an intensive care medicine resident. Cervical ultrasound is performed with a linear probe, followed by a color Doppler examination to evaluate the vascular anatomy of the anterior neck region and identify the thyroid isthmus, cricoid cartilage, and first 3 tracheal rings. The midline distance between the skin and the trachea and the tracheal diameter are measured at the second ring level. The vessels between the skin and tracheal rings are identified and avoided. The orotracheal tube is then identified and pulled under direct ultrasound guidance until the cuff is at the cricoid cartilage level to avoid cuff puncture. The puncture site is marked between the second and third tracheal rings with the ultrasound probe in the longitudinal plane and compared with the previously defined puncture site based on anatomical landmarks. The trachea is then punctured under ultrasound guidance with the probe in the transverse plane at the midline, with a catheter-overthe-needle device connected to a 10-mL syringe half-filled with distilled water. As soon as air aspiration is observed in the syringe, the catheter is advanced into the trachea and the needle is removed. A flexible guide wire is then gently introduced into the catheter, which is removed after this step. The ultrasound is then repeated to verify the adequate positioning of the guide wire. Thereafter, the procedure is completed as previously described by Griggs et al [3] or Ciaglia et al [4] according to senior physician preference and experience.” Ultrasound-guided PDT proved to be an effective method because no surgical conversion was necessary in any of the procedures and only 1 caserequired bronchoscopy assistance after early guide wire withdrawal. In this patient, the tracheal puncture was performed under US guidance, as previously described; and the trachea was dilated using the technique of Griggs et al [3]. After tracheal dilation, the guide wire was unintentionally removed along with the forceps; and the responsible physicianrequestedbronchoscopyassistancejusttoinsertthetracheostomy cannula to avoid tracheostomy misplacement. Thus, this patient was counted as 1 of the 49 patients managed with US guidance. None of the patients was described as having thyroidal pathologies or tracheal deviations. Although actively searched during US examination as part of tracheal puncture site definition, anatomical abnormalities were considered present only if previously described in patients’ imaging examinations or reported in patients’ charts. However, the retrospective nature and small sample may have limited the evaluation of anatomical abnormalities in our study.