Introduction. We systematically evaluated the use of transthoracic echocardiography in the assessment of dynamic markers of preload to predict fluid responsiveness in the critically ill adult patient. Methods. Studies in the critically ill using transthoracic echocardiography (TTE) to predict a response in stroke volume or cardiac output to a fluid load were selected. Selection was limited to English language and adult patients. Studies on patients with an open thorax or abdomen were excluded. Results. The predictive power of diagnostic accuracy of inferior vena cava diameter and transaortic Doppler signal changes with the respiratory cycle or passive leg raising in mechanically ventilated patients was strong throughout the articles reviewed. Limitations of the technique relate to patient tolerance of the procedure, adequacy of acoustic windows, and operator skill. Conclusions. Transthoracic echocardiographic techniques accurately predict fluid responsiveness in critically ill patients. Discriminative power is not affected by the technique selected.

SummaryWe examined systematically all controlled and cross-over randomised trials in patients with acute exacerbations of asthma and chronic obstructive pulmonary disease comparing Heliox against air-oxygen mixtures. Fourteen studies were identified. In asthma studies, peak expiratory flow rate (PEFR) was increased by an average of 29.6% (95% CI 16.6-42.6) by Heliox-driven nebulisers, or by 13.3 l.min )1 (95% CI 3.71-22.81) absolute. In studies of patients with chronic obstructive pulmonary disease receiving non-invasive ventilation the arterial carbon dioxide tension (P a CO 2 ) and respiratory rate were unchanged: weighted mean difference for P a CO 2 )0.29kPa (95% CI ) 0.64-0.07) favoured Heliox, and for respiratory rate 1.6 breaths.min )1 (95% CI ) 0.93, 4.14) favoured control. Heliox minimally reduced the work of breathing in intubated patients, and reduced intrinsic positive end expiratory pressure (iPEEP). The use of Heliox to drive nebulisers in patients with acute asthma slightly improves airflow measures. We were unable to determine whether this improved recovery. Helium is an inert and pharmacologically inactive gas with a density one eighth that of nitrogen. Helium (70-80%) blended with oxygen (Heliox) has a density one-third that of room air. In the first to tenth generations of human airways, gas flow is predominantly turbulent due to the branching structure of the bronchial tree. Resistance to gas flow is densitydependent and so gases with a lower density than air should reduce the work of breathing. Gas flow beyond the tenth generation is laminar and hence is densityindependent [1].Heliox was first used in patients with acute asthma and upper airway obstruction by Barach in 1934, who observed some relief of dyspnoea [2]. However, despite the theoretical benefits of Heliox where the work of breathing overloads respiratory capacity, such as acute exacerbations of asthma and chronic obstructive pulmonary disease (COPD), it has not been widely adopted in the seven decades since its clinical use was first described. Our aim was to determine whether this was due to a lack of evidence or a lack of efficacy. Systematic reviews of the use of Heliox include a Cochrane review in spontaneously breathing patients, without artificial airways, with exacerbations of asthma. That review combines adult and paediatric data and was last updated in 2002 [3]. A Cochrane review was also carried out for Heliox use in exacerbations of COPD in 2000 [4]. Only two studies were included due to a lack of data availability. Further studies on this subject have since been published.We therefore report an up-to-date systematic review of the use of Heliox in adult patients presenting with exacerbations of asthma and COPD. MethodsWe searched Medline, EMBASE and the National Research Register in November 2005. Search terms Anaesthesia, 2007Anaesthesia, , 62, pages 34-42 doi:10.1111Anaesthesia, /j.1365Anaesthesia, -2044Anaesthesia, .2006.04897. x ....................................................................................

Background Anorexia nervosa affects most organ systems, with 80% suffering from cardiovascular complications. Aims To define echocardiographic abnormalities in anorexia nervosa through systematic review and meta-analysis. Method Two reviewers independently assessed eligibility of publications from Medline, EMBASE and Cochrane Database of Systematic Reviews registries. Studies were included if anorexia nervosa was the primary eating disorder and the main clinical association in described cardiac abnormalities. Data was extracted in duplicate and quality-assessed with a modified Newcastle–Ottawa scale. For continuous outcomes we calculated mean and standardised mean difference (SMD), and corresponding 95% confidence interval. For dichotomous outcomes we calculated proportion and corresponding 95% confidence interval. For qualitative data we summarised the studies. Results We identified 23 eligible studies totalling 960 patients, with a mean age of 17 years and mean body mass index of 15.2 kg/m2. Fourteen studies (469 participants) reported data suitable for meta-analysis. Cardiac abnormalities seen in anorexia nervosa compared with healthy controls were reduced left ventricular mass (SMD 1.82, 95% CI 1.32–2.31, P < 0.001), reduced cardiac output (SMD 1.92, 95% CI 1.38–2.45, P < 0.001), increased E/A ratio (SMD −1.10, 95% CI −1.67 to −0.54, P < 0.001), and increased incidence of pericardial effusions (25% of patients, P < 0.01, 95% CI 17–34%, I2 = 80%). Trends toward improvement were seen with weight restoration. Conclusions Patients with anorexia nervosa have structural and functional cardiac changes, identifiable with echocardiography. Further work should determine whether echocardiography can help stratify severity and guide safe patient location, management and effectiveness of nutritional rehabilitation.

The British Society of Echocardiography has previously outlined a minimum dataset for a standard transthoracic echocardiogram, and this remains the basis on which an echocardiographic study should be performed. The importance of ultrasound in excluding critical conditions that may require urgent treatment is well known. Several point-of-care echo protocols have been developed for use by non-echocardiography specialists. However, these protocols are often only used in specific circumstances and are usually limited to 2D echocardiography. Furthermore, although the uptake in training for these protocols has been reasonable, there is little in the way of structured support available from accredited sonographers in the ongoing training and re-accreditation of those undertaking these point-of-care scans. In addition, it is well recognised that the provision of echocardiography on a 24/7 basis is extremely challenging, particularly outside of tertiary cardiac centres. Consequently, following discussions with NHS England, the British Society of Echocardiography has developed the Level 1 echocardiogram in order to support the rapid identification of critical cardiac pathology that may require emergency treatment. It is intended that these scans will be performed by non-specialists in echocardiography and crucially are not designed to replace a full standard transthoracic echocardiogram. Indeed, it is expected that a significant number of patients, in whom a Level 1 echocardiogram is required, will need to have a full echocardiogram performed as soon as is practically possible. This document outlines the minimum dataset for a Level 1 echocardiogram. The accreditation process for Level 1 echo is described separately.

JICS 128 the critically ill. Further studies should concentrate on Doppler-based assessments. The scene is now set for the development of this valuable non-invasive tool.