What is the normal haemodynamic response to passive leg raise? A study of healthy volunteers.

OBJECTIVE: Passive leg raise (PLR) is used as self-fluid challenge to optimise fluid therapy by predicting preload responsiveness. However, there remains uncertainty around the normal haemodynamic response to PLR with resulting difficulties in application and interpretation in emergency care. We aim to define the haemodynamic responses to PLR in spontaneously breathing volunteers using a non-invasive cardiac output monitor, thoracic electrical bioimpedance, TEB (PLR-TEB). METHODS: We recruited healthy volunteers aged 18 or above. Subjects were monitored using TEB in a semirecumbent position, followed by PLR for 3 min. The procedure was repeated after 6 min at the starting position. Correlation between the two PLRs was assessed using Spearman's r (rs). Agreement between the two PLRs was evaluated using Cohen Kappa with responsiveness defined as ≥10% increase in stroke volume. Parametric and non-parametric tests were used as appropriate to evaluate statistical significance of baseline variables between responders and non-responders. RESULTS: We enrolled 50 volunteers, all haemodynamically stable at baseline, of whom 49 completed the study procedure. About half of our subjects were preload responsive. The ∆SV in the two PLRs was correlated (rs=0.68, 95% CI 0.49 to 0.8) with 85% positive concordance. Good agreement was observed with Cohen Kappa of 0.67 (95% CI 0.45 to 0.88). Responders were older and had significantly lower baseline stroke volume and cardiac output. CONCLUSION: Our results suggest that the PLR-TEB is a feasible method in spontaneously breathing volunteers with reasonable reproducibility. The age and baseline stroke volume effect suggests a more complex underlying physiology than commonly appreciated. The fact that half of the volunteers had a positive preload response, against the 10% threshold, leads to questions about how this measurement should be used in emergency care and will help shape future patient studies.

The haemodynamic dilemma in emergency care: Is fluid responsiveness the answer? A systematic review.

BACKGROUND: Fluid therapy is a common and crucial treatment in the emergency department (ED). While fluid responsiveness seems to be a promising method to titrate fluid therapy, the evidence for its value in ED is unclear. We aim to synthesise the existing literature investigating fluid responsiveness in ED. METHODS: MEDLINE, Embase and the Cochrane library were searched for relevant peer-reviewed studies published from 1946 to present. RESULTS: A total of 249 publications were retrieved of which 22 studies underwent full-text review and eight relevant studies were identified. Only 3 studies addressed clinical outcomes - including 2 randomised controlled trials and one feasibility study. Five articles evaluated the diagnostic accuracy of fluid responsiveness techniques in ED. Due to marked heterogeneity, it was not possible to combine results in a meta-analysis. CONCLUSION: High quality, adequately powered outcome studies are still lacking, so the place of fluid responsiveness in ED remains undefined. Future studies should have standardisation of patient groups, the target response and the underpinning theoretic concept of fluid responsiveness. The value of a fluid responsiveness based fluid resuscitation protocol needs to be established in a clinical trial.

The role of 64/128-slice multidetector computed tomography to assess the progression of coronary atherosclerosis.

OBJECTIVES: We studied the progression of coronary atherosclerosis over time as detected by multidetector computed tomography (MDCT) in relation to risk factors and plaque composition. BACKGROUND: Studies using MDCT are limited to the assessment of the degree of stenosis without taking into consideration the plaque composition that is seen by MDCT. METHODS: This study included 200 patients, complaining of chest pain and referred to do 64/128-contrast-enhanced MDCT for the second time, and both studies were retrieved and evaluated for the presence of plaque, plaque type, vessel wall remodeling, percent area, and diameter stenosis and compared in both studies. Plaque progression over time and its association with risk factors were determined. RESULTS: We included 200 patients, and 348 plaques were detected by 64/128 MDCT. The duration between follow-up and baseline studies was 25.9 ± 19.2 month. In all, 200 plaques showed progression (57.47%), 122 were stable (35.06%), and 26 regressed (7.47%). In longitudinal regression analysis, the presence of history of diabetes mellitus and dyslipidemia and the absence of intraplaque calcium deposits were independently associated with plaque progression over time (P < 0.0001). CONCLUSION: Coronary plaque burden of patients with chest pain and no history of acute coronary syndrome significantly increased over time. Progression is dependent on plaque composition and cardiovascular risk factors. Larger studies and longer follow-up period are needed to confirm the determinant factors for plaque progression.