Dynamic monitoring tools for patients admitted to the emergency department with circulatory failure: narrative review with panel-based recommendations.

Intravenous fluid therapy is commonly administered in the emergency department (ED). Despite the deleterious potential of over- and under-resuscitation, professional society guidelines continue to recommend administering a fixed volume of fluid in initial resuscitation. Predicting whether a specific patient will respond to fluid therapy remains one of the most important, but challenging questions that ED clinicians face in clinical practice. Surrogate parameters (i.e. blood pressure and heart rate), are widely used in usual care to estimate changes in stroke volume (SV). Due to their inadequacy in estimating SV, noninvasive techniques (e.g. bioreactance, echocardiography, noninvasive finger cuff technology), have been proposed as a more accurate and readily deployable method for assessing flow and preload responsiveness. Dynamic monitoring systems based on cardiac preload challenge and assessment of SV, by using noninvasive and continuous methods, provide more accurate, feasible, efficient, and reasonably accurate strategy for prediction of fluid responsiveness than static measurements. In this article, we aimed to analyze the different methods currently available for dynamic monitoring of preload responsiveness.

Fluid therapy in the emergency department: an expert practice review.

Intravenous fluid therapy is one of the most common therapeutic interventions performed in the ED and is a long-established treatment. The potential benefits of fluid therapy were initially described by Dr W B O'Shaughnessy in 1831 and first administered to an elderly woman with cholera by Dr Thomas Latta in 1832, with a marked initial clinical response. However, it was not until the end of the 19th century that medicine had gained understanding of infection risk that practice became safer and that the practice gained acceptance. The majority of fluid research has been performed on patients with critical illness, most commonly sepsis as this accounts for around two-thirds of shocked patients treated in the ED. However, there are few data to guide clinicians on fluid therapy choices in the non-critically unwell, by far our largest patient group. In this paper, we will discuss the best evidence and controversies for fluid therapy in medically ill patients.

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.

Thoracic electrical bioimpedance versus suprasternal Doppler in emergency care.

OBJECTIVE: There are a number of cardiac output (CO) monitors that could potentially be used in the ED. Two of the most promising methods, thoracic electrical bioimpedance and suprasternal Doppler, have not been directly compared. The aim of this study was to investigate the feasibility of CO monitoring using suprasternal Doppler and bioimpedance in emergency care and compare haemodynamic data obtained from both monitors. METHODS: Haemodynamic measurements were made on the same group of patients using bioimpedance (Niccomo, Medis, Germany) and suprasternal Doppler (USCOM, Sydney, Australia). RESULTS: Usable CO data were obtained in 97% of patients by suprasternal Doppler and 87% by bioimpedance. The median CO obtained by Doppler was 3.4 L/min lower than bioimpedance. The stroke volume median was lower by 51 mL in Doppler. CONCLUSIONS: These two methods of non-invasive cardiac monitoring are not interchangeable. The results suggest that the choice of non-invasive cardiac monitor is important, but the grounds on which to make this choice are not currently clear.

Valsalva using a syringe: pressure and variation.

BACKGROUND: The Valsalva manoeuvre is commonly used in EDs to terminate supraventricular tachycardia by the patient blowing into a syringe. AIM: To identify whether a specific syringe size can be recommended for use in the ED. RESULTS: 20% of syringes 'stuck' and required high pressures to move. In the remaining 80% of syringes, a 20 mL syringe was the most appropriate size to achieve the recommended 40 mm Hg. Once 'released' plunger position did not make a difference. CONCLUSIONS: Use of a syringe of any size cannot be recommended if a consistent pressure is required.