Vasileios Zochios

Extracorporeal membrane oxygenation in acute massive pulmonary embolism: a systematic review:

Massive pulmonary embolism (PE) can present with extreme physiological dysfunction, characterised by acute right ventricular failure, hypoxaemia unresponsive to conventional therapy and cardiac arrest. Consensus regarding the management of patients with persistent shock following thrombolysis is lacking. Our primary objective was to describe the application of extracorporeal membrane oxygenation (ECMO) in the treatment of acute massive PE. We were unable to identify any randomised controlled trials (RCTs) comparing ECMO with other support systems in the setting of massive PE. We reviewed case reports and case series published in the past 20 years to evaluate the mortality rate and any poor prognostic factors. Overall survival was 70.1% and none of the definitive treatment modalities was associated with a higher mortality (thrombolysis - OR - 0.99, P - 0.9, catheter embolectomy - OR - 1.01, P - 0.99, surgical embolectomy - OR - 0.44, P - 0.20). Patients who had ECMO instituted whilst in cardiorespiratory arrest had a higher risk of death. (OR - 16.71, P - 0.0004). When compared with other causes of cardiac arrest, patients who survived a massive PE presented a good neurological outcome (cerebral performance category 1 or 2).

Peripherally inserted central catheter (PICC)-related thrombosis in critically ill patients

Background Peripherally inserted central catheters (PICC) are being increasingly used in critical care setting. However, PICCs are associated with a number of complications, particularly upper extremity venous thrombosis (UEVT), leading to post-thrombotic syndrome, pulmonary embolism and increased risk of catheter-related infection. Objective To review the literature surrounding PICCs and highlight the epidemiology, pathophysiology, diagnosis and management of PICC-related thrombosis in critically ill patients. Data sources and extraction We performed an electronic literature search of the databases PubMed, EMBASE and Google scholar using set search terms, from their commencement date to the end of January 2014. Summary of review It has been shown that PICCs may double the risk of deep venous thrombosis compared with centrally inserted venous catheters, in critically ill patients. However, the incidence of PICC-related thrombosis in critically ill patients has not been quantified. Ultrasonography is the preferred diagnostic imaging modality. There are no randomized controlled trials (RCTs) on the best treatment of PICC-related thrombosis in the intensive care unit (ICU) setting and in most cohort studies, anticoagulation strategies with or without PICC removal have been used. Conclusions Decision to insert a PICC should be taken after careful risk stratification. There is lack of high-quality evidence assessing prevention strategies and management of PICC-related thrombosis in the ICU. Well-designed RCTs are required to estimate the prevalence of UEVT in ICU patients with PICCs and evaluate the efficacy and magnitude of clinical benefit and cost-effectiveness of therapeutic strategies.

Physiological controversies and methods used to determine fluid responsiveness: a qualitative systematic review.

Accurate assessment of intravascular fluid status and measurement of fluid responsiveness have become increasingly important in peri‐operative medicine and critical care. The objectives of this systematic review and narrative synthesis were to discuss current controversies surrounding fluid responsiveness and describe the merits and limitations of the major cardiac output monitors in clinical use today in terms of usefulness in measuring fluid responsiveness. We searched the MEDLINE and EMBASE databases (2002–2015); inclusion criteria included comparison with an established reference standard such as pulmonary artery catheter, transthoracic echocardiography and transoesophageal echocardiography. Examples of clinical measures include static (such as central venous pressure) and dynamic (such as stroke volume variation and pulse pressure variation) parameters. The static parameters measured were described as having little value; however, the dynamic parameters were shown to be good physiological determinants of fluid responsiveness. Due to heterogeneity of the methods and patient characteristics, we did not perform a meta‐analysis. In most studies, precision and limits of agreement (bias ±1.96SD) between determinants of fluid responsiveness measured by different devices were not evaluated, and the definition of fluid responsiveness varied across studies. Future research should focus on the physiological principles that underlie the measurement of fluid responsiveness and the effect of different volume expansion strategies on outcomes.

The role of ultrasound as an adjunct to arterial catheterization in critically ill surgical and intensive care unit patients

Objective To review the evidence behind Ultrasound (US) guided placement of arterial cannulae and its use in the critically ill population. Data sources We performed a computer-aided literature search using set search terms and electronic data bases of PubMed and EMBASE from their commencement date through the end of July 2013. Summary of review Insertion of intra-arterial catheters is a commonly performed invasive procedure in the peri-operative and intensive care setting that facilitates invasive blood pressure and cardiac output monitoring as well as frequent blood sampling. Arterial catheterization can be particularly challenging in critically ill and high-risk surgical patients with circulatory collapse, low cardiac output state and peripheral edema, all of which can limit the ability to successfully palpate and cannulate the artery. There is a convincing body of evidence suggesting a decrease in complication rate and first-pass success rate in US guided central venous catheter (CVC) insertion compared with the landmark technique. While most intensivists and peri-operative physicians are familiar with US guided CVC placement, fewer use US to guide arterial access. Conclusions Most studies have demonstrated a higher success rate when using US guidance for arterial cannulation. Moreover, the technique permits more rapid access and establishment compared with the conventional palpation technique. However, there is evidence opposing the routine use of US to guide arterial cannula insertion. Further studies are required to ascertain the benefits and cost effectiveness of US guided arterial catheterization in peri-operative and critical care.

The Right Ventricle in ARDS

&NA; ARDS is associated with poor clinical outcomes, with a pooled mortality rate of approximately 40% despite best standards of care. Current therapeutic strategies are based on improving oxygenation and pulmonary compliance while minimizing ventilator‐induced lung injury. It has been demonstrated that relative hypoxemia can be well tolerated, and improvements in oxygenation do not necessarily translate into survival benefit. Cardiac failure, in particular right ventricular dysfunction (RVD), is commonly encountered in moderate to severe ARDS and is reported to be one of the major determinants of mortality. The prevalence rate of echocardiographically evident RVD in ARDS varies across studies, ranging from 22% to 50%. Although there is no definitive causal relationship between RVD and mortality, severe RVD is associated with increased mortality. Factors that can adversely affect RV function include hypoxic pulmonary vasoconstriction, hypercapnia, and invasive ventilation with high driving pressure. It might be expected that early diagnosis of RVD would be of benefit; however, echocardiographic markers (qualitative and quantitative) used to prospectively evaluate the right ventricle in ARDS have not been tested in adequately powered studies. In this review, we examine the prognostic implications and pathophysiology of RVD in ARDS and discuss available diagnostic modalities and treatment options. We aim to identify gaps in knowledge and directions for future research that could potentially improve clinical outcomes in this patient population.

Tropical diseases of the myocardium: a review

Cardiovascular diseases are widely distributed throughout the world. Human parasitic infections are ubiquitous. Tropical parasites are increasingly recognized as causes of cardiovascular diseases. In this review, we address the most frequently reported parasites that directly infect the myocardium, including Trypanosoma cruzi, the protozoal causative agent of American trypanosomiasis (Chagas disease), and Taenia solium, the cestode causative agent of taeniasis and cysticercosis. We also discuss tropical endomyocardial fibrosis, trichinellosis and schistosomiasis. Health systems, attitudes, the perceptions of both patients and physicians as well as socioeconomic factors should all be explored and recognized as crucial factors for improving the control of cardiovascular diseases in the tropics. Clinicians throughout the world must remain aware of imported parasites as potential causes of cardiac diseases.

Effect of High-Flow Nasal Oxygen on Pulmonary Complications and Outcomes After Adult Cardiothoracic Surgery: A Qualitative Review

IGH-FLOW NASAL OXYGEN (HFNO) therapy delivers low-level, flow-dependent positive airway pressure and may be tolerated better than continuous positive airway pressure (CPAP) or noninvasive bi-level positive airway pressure (BiPAP) and enhance washout of nasopharyngeal deadspace, thus improving oxygenation. 1,2 The apparatus is composed of an air/oxygen blender, an active heated humidifier, a single heated circuit, and a nasal cannula. At the air/ oxygen blender, the inspiratory fraction of oxygen (FIO2) is set from 0.21 to 1.0 at a flow of up to 60 L/min. The gas is heated and humidified with the active humidifier and delivered through the heated circuit. Theoretically, HFNO has a number of advantages over other respiratory support systems, including conventional nasal cannulae, face masks, or CPAP/BiPAP. First, because gas generally is warmed to 371C and completely humidified in HFNO circuits, mucociliary function remains intact and patients report minimal discomfort. Mechanical splinting of the nasopharynx prevents supraglottic collapse and decreases nasopharyngeal resistance, and at 60 L/min HFNO can generate positive end-expiratory pressure (PEEP) of 4 to 7.4 cmH2O, which may counterbalance auto-PEEP and reduce the work of breathing. 3,4 HFNO therapy has been gaining attention as an innovative form of respiratory support in various clinical settings. It is being used increasingly in critically ill patients and gaining favor in the perioperative period. HFNO has been used for multiple indications, including hypoxemic respiratory failure and cardiogenic pulmonary edema, to counterbalance autoPEEP in patients with chronic obstructive airway disease and as prophylactic therapy or treatment of respiratory failure after surgery and extubation. 5 It has been shown to be both safe and noninferior to conventional CPAP in providing prophylactic support to very preterm neonates after extubation. 6 In this same study, the incidence of nasal trauma also was significantly lower in the nasal cannulae group than in the CPAP group. Little clinical experience has been reported on the use of HFNO in the cardiothoracic surgical patient population. Patients undergoing cardiothoracic surgery are at significant risk of postoperative pulmonary complications, and these complications may increase morbidity and mortality and lead to prolonged intensive care unit and hospital length of stay. 7 The incidence of pulmonary complications ranges from 8% to 79% after cardiac surgery and has been reported to be as high as 50% after lung resection surgery. 8 Postoperative pulmonary complications manifest early as arterial hypoxemia, during the later course as pneumonia, and in rare cases also as acute respiratory distress syndrome. 9 The pathogenesis of

Current state of glycemic control in critically ill subjects in a general intensive care unit

Critically ill patients are predisposed to stress-induced hyperglycemia. Recent evidence suggests that uncontrolled hyperglycemia is associated with poor outcomes within the population of surgical and medical intensive care units. We retrospectively audited our practice in the management of hyperglycemia in the critically ill, in order to identify reasons and periods of time that deviations in blood glucose control are most likely, and to make recommendations on how to improve this. Our study showed poor compliance with the current recommendations for glycemic control in the critically ill and highlighted the need for a successful protocol for glycemic control in our institution. That should be carefully coordinated with the level of nutritional support and metabolic status of the acutely ill patient.

Re-examining Permissive Hypercapnia in ARDS: A Narrative Review

&NA; Lung‐protective ventilation (LPV) has become the cornerstone of management in patients with ARDS. A subset of patients is unable to tolerate LPV without significant CO2 elevation. In these patients, permissive hypercapnia is used. Although thought to be benign, it is becoming increasingly evident that elevated CO2 levels have significant physiological effects. In this narrative review, we highlight clinically relevant end‐organ effects in both animal models and clinical studies. We also explore the association between elevated CO2, acute cor pulmonale, and ICU mortality. We conclude with a brief review of alternative therapies for CO2 management currently under investigation in patients with moderate to severe ARDS.

Stridor in adult patients presenting from the community: An alarming clinical sign

Following our recent management of an adult patient with stridor, we performed a systematic review of published case reports and case series of adult patients presenting to the emergency department with stridor. The aim of our search was to outline the underlying causes of stridor in adults and we present our findings below. Our experience also emphasises the need for immediate management using a multi-disciplinary approach. We performed a PubMed literature search from January 1951 to September 2014 using the following medical subject heading terms: ‘stridor’ OR ‘stridorous’ OR ‘stridors’ [Title], in English. Stridor was reported in 249 patients from 99 publications (87 were single-patient case reports). We excluded reports on children and hospital acquired stridors (as a complication of tracheal intubation/general anaesthesia, thyroidectomy, pneumonectomy, nerve injury or other) as their management follows different pathways. Malignant obstruction was reported in 15 patients. Fifty six percent of the reported patients were female. Approximately 50% of patients required definitive airway management, invasive ventilation and admission to the intensive care unit (ICU). The overall mortality rate was 6.4%. The identified aetiologies of the cases are summarised in Table 1. The commonest systemic cause of stridor was neurological (65 patients from 13 papers). The commonest neurological cause was multiple system atrophy (53 patients) followed by myasthenia gravis (five patients). The commonest local causes were vocal cord conditions (27 patients from 10 papers). Fifty-three patients from three reports had psychogenic stridor, a diagnosis of exclusion. The number of reported local causes for stridor was 59 versus 40 systemic causes. Subgroup analysis of obscure laryngeal causes of stridor revealed: redundant aryepiglottic fold (seven patients), focal dystonia (six patients), functional dyskinesia (six patients), paradoxical motion (five patients), laryngocele (one patient), subglottic stenosis (one patient) and tracheomalacia (one patient). Regardless of cause, stridor implies critical airway obstruction of at least 50% of the airway lumen. Patients with stridor are at high risk of respiratory failure and death and require initial stabilisation to maintain ventilation and oxygenation, if this is consistent with the goals of care. The degree of respiratory distress depends on whether partial airway obstruction has developed gradually (e.g. laryngeal tumour) or rapidly (e.g. acute epiglottitis). Unless resolved promptly in the emergency department, Table 1. Causes of stridor in adults presenting from the community as identified from a review of published case reports and case series.