Development of clinical tools to estimate the breathing effort during high-flow oxygen therapy: A multicenter cohort study.

INTRODUCTION AND OBJECTIVES: Quantifying breathing effort in non-intubated patients is important but difficult. We aimed to develop two models to estimate it in patients treated with high-flow oxygen therapy. PATIENTS AND METHODS: We analyzed the data of 260 patients from previous studies who received high-flow oxygen therapy. Their breathing effort was measured as the maximal deflection of esophageal pressure (ΔPes). We developed a multivariable linear regression model to estimate ΔPes (in cmH2O) and a multivariable logistic regression model to predict the risk of ΔPes being >10 cmH2O. Candidate predictors included age, sex, diagnosis of the coronavirus disease 2019 (COVID-19), respiratory rate, heart rate, mean arterial pressure, the results of arterial blood gas analysis, including base excess concentration (BEa) and the ratio of arterial tension to the inspiratory fraction of oxygen (PaO2:FiO2), and the product term between COVID-19 and PaO2:FiO2. RESULTS: We found that ΔPes can be estimated from the presence or absence of COVID-19, BEa, respiratory rate, PaO2:FiO2, and the product term between COVID-19 and PaO2:FiO2. The adjusted R2 was 0.39. The risk of ΔPes being >10 cmH2O can be predicted from BEa, respiratory rate, and PaO2:FiO2. The area under the receiver operating characteristic curve was 0.79 (0.73-0.85). We called these two models BREF, where BREF stands for BReathing EFfort and the three common predictors: BEa (B), respiratory rate (RE), and PaO2:FiO2 (F). CONCLUSIONS: We developed two models to estimate the breathing effort of patients on high-flow oxygen therapy. Our initial findings are promising and suggest that these models merit further evaluation.

Hemodynamic resuscitation with fluids bolus and norepinephrine increases severity of lung damage in an experimental model of septic shock / La resucitación hemodinámica con bolos de fluidos y noradrenalina incrementa la severidad del daño pulmonar en un modelo experimental de shock séptico

Objective Hemodynamic resuscitation is considered a cornerstone of the initial treatment of septic shock. However, there is growing concern about its side effects. Our objective was to assess the relationship between fluid administration and norepinephrine infusion and the development of lung injury. Design Randomized in vivo study in rabbits. Setting University animal research laboratory. Patients Eighteen New Zealand rabbits. Control group (SHAM, n=6), Sepsis group with or without hemodynamic resuscitation (ETX-R, n=6; ETX-NR, n=6). Interventions Sepsis was induced by intravenous lipopolysaccharide administration and animals were followed-up for 4h. Hemodynamic resuscitation with Ringer lactate (20mL·kg−1) was administered and later norepinephrine was initiated 3h after sepsis induction. At the end, the left lung was excised. Main variables of interestAn indwelling arterial catheter and an esophageal Doppler were placed. Lung mechanics were monitored with side stream spirometry. Lung damage was analyzed by histopathological examination. Results The SHAM group did not show hemodynamic or respiratory changes. Lipopolysaccharide administration aimed an increase in cardiac output and arterial hypotension. In the ETX-NR group, animals remained hypotensive until the end of the experiment. Resuscitation with fluids and norepinephrine reversed arterial hypotension. Compared to the ETX-NR group, the remaining lung of the ETX-R group showed greater accumulation of neutrophils and reactive type-II pneumocytes, thicker alveolar wall, alveolar hemorrhage and non-aerated pulmonary areas. Lung injury score was larger in the ETX-R group. Conclusions In our experimental study, following a strategy with bolus fluids and late norepinephrine used in the early phase of endotoxic septic shock has a negative influence on the development of lung injury. (AU)

Objetivo La resucitación hemodinámica es considerada piedra angular en el tratamiento inicial del shock séptico. Sin embargo, existe creciente preocupación sobre sus efectos indeseables. Nuestro objetivo fue evaluar la relación entre la administración de fluidos e infusión de noradrenalina y el desarrollo de lesión pulmonar. Diseño Estudio aleatorizado en animales vivos. Ámbito Laboratorio universitario de investigación. Participantes Dieciocho conejos de raza New Zealand White. Grupo control (SHAM, n=6), grupo séptico con o sin resucitación hemodinámica (ETX-R, n=6; ETX-NR, n=6). Intervención La sepsis fue inducida tras administración intravenosa de lipopolisacárido, y los animales fueron seguidos durante 4h. La resucitación hemodinámica mediante suero Ringer lactato (20ml·kg-1) y posterior noradrenalina fue iniciada a las 3h de ser inducida la sepsis. Al final del estudio, el pulmón izquierdo fue extraído. Principales variables de interés Fueron empleados catéter arterial y doppler esofágico. La mecánica pulmonar fue monitorizada con sensor de flujo. El daño pulmonar fue analizado mediante examen histopatológico. Resultados El grupo control no mostró cambios hemodinámicos ni respiratorios. La administración del lipopolisacárido produjo un incremento del gasto cardíaco e hipotensión arterial. En el grupo ETX-NR, los animales permanecieron hipotensos hasta el final del estudio. La resucitación con fluidos y noradrenalina revirtió la hipotensión arterial. Comparados con el grupo ETX-NR, en el grupo ETX-R el estudio histopatológico mostró mayor acumulación de neutrófilos, así como mayor presencia de neumocitos activados tipo II, engrosamiento de la pared alveolar, hemorragia alveolar y zonas pulmonares no aireadas. La escala final de daño pulmonar fue mayor en el grupo ETX-R. Conclusiones En nuestro estudio experimental ... (AU)

Hemodynamic resuscitation with fluids bolus and norepinephrine increases severity of lung damage in an experimental model of septic shock.

OBJECTIVE: Hemodynamic resuscitation is considered a cornerstone of the initial treatment of septic shock. However, there is growing concern about its side effects. Our objective was to assess the relationship between fluid administration and norepinephrine infusion and the development of lung injury. DESIGN: Randomized in vivo study in rabbits. SETTING: University animal research laboratory. PATIENTS: Eighteen New Zealand rabbits. Control group (SHAM, n=6), Sepsis group with or without hemodynamic resuscitation (ETX-R, n=6; ETX-NR, n=6). INTERVENTIONS: Sepsis was induced by intravenous lipopolysaccharide administration and animals were followed-up for 4h. Hemodynamic resuscitation with Ringer lactate (20mL·kg-1) was administered and later norepinephrine was initiated 3h after sepsis induction. At the end, the left lung was excised. MAIN VARIABLES OF INTEREST: An indwelling arterial catheter and an esophageal Doppler were placed. Lung mechanics were monitored with side stream spirometry. Lung damage was analyzed by histopathological examination. RESULTS: The SHAM group did not show hemodynamic or respiratory changes. Lipopolysaccharide administration aimed an increase in cardiac output and arterial hypotension. In the ETX-NR group, animals remained hypotensive until the end of the experiment. Resuscitation with fluids and norepinephrine reversed arterial hypotension. Compared to the ETX-NR group, the remaining lung of the ETX-R group showed greater accumulation of neutrophils and reactive type-II pneumocytes, thicker alveolar wall, alveolar hemorrhage and non-aerated pulmonary areas. Lung injury score was larger in the ETX-R group. CONCLUSIONS: In our experimental study, following a strategy with bolus fluids and late norepinephrine used in the early phase of endotoxic septic shock has a negative influence on the development of lung injury.

Ten answers to key questions for fluid management in intensive care.

This review focuses on fluid management of critically ill patients. The topic is addressed based on 10 single questions with simplified answers that provide clinicians with the basic information needed at the point of care in treating patients in the Intensive Care Unit. The review has didactic purposes and may serve both as an update on fluid management and as an introduction to the subject for novices in critical care. There is an urgent need to increase awareness regarding the potential risks associated with fluid overload. Clinicians should be mindful not only of the indications for administering fluid loads and of the type of fluids administered, but also of the importance to set safety limits. Lastly, it is important to implement proactive strategies seeking to establish negative fluid balance as soon as the clinical conditions are considered to be stable and the risk of deterioration is low.

Rationale and evidence on the use of tocilizumab in COVID-19: a systematic review.

BACKGROUND: Tocilizumab is an IL-6 receptor-blocking agent proposed for the treatment of severe COVID-19. The aim of this systematic review was to describe the rationale for the use of tocilizumab for the treatment of COVID-19 and to summarize the available evidence regarding its efficacy and safety. METHODS: MEDLINE, PubMed, EMBASE, pre-print repositories (bioRxiv and medRxiv) and two trial Registries were searched for studies on the use of tocilizumab in COVID-19 or SARS-CoV-2 infection, viral pneumonia, and/or sepsis until 20th June 2020. RESULTS: We identified 3 indirect pre-clinical studies and 28 clinical studies including 5776 patients with COVID-19 (13 with a comparison group, 15 single-arm). To date, no randomized trials have been published. We retrieved no studies at low risk of bias. Forty-five ongoing studies were retrieved from trial registries. CONCLUSIONS: There is insufficient evidence regarding the clinical efficacy and safety of tocilizumab in patients with COVID-19. Its use should be considered experimental, requiring ethical approval and clinical trial oversight.

Ten answers to key questions for fluid management in intensive care.

This review focuses on fluid management of critically ill patients. The topic is addressed based on 10 single questions with simplified answers that provide clinicians with the basic information needed at the point of care in treating patients in the Intensive Care Unit. The review has didactic purposes and may serve both as an update on fluid management and as an introduction to the subject for novices in critical care. There is an urgent need to increase awareness regarding the potential risks associated with fluid overload. Clinicians should be mindful not only of the indications for administering fluid loads and of the type of fluids administered, but also of the importance to set safety limits. Lastly, it is important to implement proactive strategies seeking to establish negative fluid balance as soon as the clinical conditions are considered to be stable and the risk of deterioration is low.

Hemodynamic resuscitation with fluids bolus and norepinephrine increases severity of lung damage in an experimental model of septic shock.

OBJECTIVE: Hemodynamic resuscitation is considered a cornerstone of the initial treatment of septic shock. However, there is growing concern about its side effects. Our objective was to assess the relationship between fluid administration and norepinephrine infusion and the development of lung injury. DESIGN: Randomized in vivo study in rabbits. SETTING: University animal research laboratory. PATIENTS: Eighteen New Zealand rabbits. Control group (SHAM, n=6), Sepsis group with or without hemodynamic resuscitation (ETX-R, n=6; ETX-NR, n=6). INTERVENTIONS: Sepsis was induced by intravenous lipopolysaccharide administration and animals were followed-up for 4h. Hemodynamic resuscitation with Ringer lactate (20mL·kg-1) was administered and later norepinephrine was initiated 3h after sepsis induction. At the end, the left lung was excised. MAIN VARIABLES OF INTEREST: An indwelling arterial catheter and an esophageal Doppler were placed. Lung mechanics were monitored with side stream spirometry. Lung damage was analyzed by histopathological examination. RESULTS: The SHAM group did not show hemodynamic or respiratory changes. Lipopolysaccharide administration aimed an increase in cardiac output and arterial hypotension. In the ETX-NR group, animals remained hypotensive until the end of the experiment. Resuscitation with fluids and norepinephrine reversed arterial hypotension. Compared to the ETX-NR group, the remaining lung of the ETX-R group showed greater accumulation of neutrophils and reactive type-II pneumocytes, thicker alveolar wall, alveolar hemorrhage and non-aerated pulmonary areas. Lung injury score was larger in the ETX-R group. CONCLUSIONS: In our experimental study, following a strategy with bolus fluids and late norepinephrine used in the early phase of endotoxic septic shock has a negative influence on the development of lung injury.

Hospital surge capacity in a tertiary emergency referral centre during the COVID-19 outbreak in Italy.

The first person-to-person transmission of the 2019 novel coronavirus in Italy on 21 February 2020 led to an infection chain that represents one of the largest known COVID-19 outbreaks outside Asia. In northern Italy in particular, we rapidly experienced a critical care crisis due to a shortage of intensive care beds, as we expected according to data reported in China. Based on our experience of managing this surge, we produced this review to support other healthcare services in preparedness and training of hospitals during the current coronavirus outbreak. We had a dedicated task force that identified a response plan, which included: (1) establishment of dedicated, cohorted intensive care units for COVID-19-positive patients; (2) design of appropriate procedures for pre-triage, diagnosis and isolation of suspected and confirmed cases; and (3) training of all staff to work in the dedicated intensive care unit, in personal protective equipment usage and patient management. Hospital multidisciplinary and departmental collaboration was needed to work on all principles of surge capacity, including: space definition; supplies provision; staff recruitment; and ad hoc training. Dedicated protocols were applied where full isolation of spaces, staff and patients was implemented. Opening the unit and the whole hospital emergency process required the multidisciplinary, multi-level involvement of healthcare providers and hospital managers all working towards a common goal: patient care and hospital safety. Hospitals should be prepared to face severe disruptions to their routine and it is very likely that protocols and procedures might require re-discussion and updating on a daily basis.

International point prevalence study of Intensive Care Unit transfusion practices-Pilot study in the Netherlands.

BACKGROUND: Anaemia and coagulopathy are common issues in critically ill patients. Transfusion can be lifesaving, however, is associated with potential life threatening adverse events. As an international transfusion guideline for this specific patient population is lacking, we hypothesize that a high heterogeneity in transfusion practices exists. In this pilot-study we assessed transfusion practice in a university hospital in the Netherlands and tested the feasibility of this protocol for an international multi-centre study. METHODS: A prospective single centre cohort study was conducted. For seven days all consecutive non-readmitted patients to the adult Intensive Care Unit (ICU) were included and followed for 28 days. Patients were prospectively followed until ICU discharge or up to day 28. Patient outcome data was collected at day 28. Workload for this study protocol was scored in hours and missing data. RESULTS: In total, 48 patients were included, needed in total three hours patient to include and collect all data, with 1.6% missing data showing the feasibility of the data acquisition. Six (12.5%) patients received red blood cells (RBCs), three patients (6.3%) received platelet concentrates, and two (4.2%) patients received plasma units. In total eight (16.7%) patients were transfused with one or more blood products. Median pre- and post-transfusion haemoglobin (Hb) levels were 7.6 (6.7-7.7) g/dL and 8.1 (7.6-8.7) g/dL, respectively. CONCLUSION: In this pilot-study we proved the feasibility of our protocol and observed in this small population a restrictive transfusion practice for all blood products.

Adoption of Lung Protective ventilation IN patients undergoing Emergency laparotomy: the ALPINE study. A prospective multicentre observational study.

BACKGROUND: Emergency abdominal surgery is associated with a high risk of postoperative pulmonary complications (PPCs). The primary aim of this study was to determine whether patients undergoing emergency laparotomy are ventilated using a lung-protective ventilation strategy employing tidal volume ≤8 ml kg-1 ideal body weight-1, PEEP >5 cm H2O, and recruitment manoeuvres. The secondary aim was to investigate the association between ventilation factors (lung-protective ventilation strategy, intraoperative FiO2, and peak inspiratory pressure) and the occurrence of PPCs. METHODS: Data were collected prospectively in 28 hospitals across London as part of routine National Emergency Laparotomy Audit (NELA). Patients were followed for 7 days. Complications were defined according to the European Perioperative Clinical Outcome definition. RESULTS: Data were collected from 568 patients. The median [inter-quartile range (IQR)] tidal volume observed was 500 ml (450-540 ml), corresponding to a median tidal volume of 8 ml kg-1 ideal body weight-1 (IQR: 7.2-9.1 ml). A lung-protective ventilation strategy was employed in 4.9% (28/568) of patients, and was not protective against the occurrence of PPCs in the multivariable analysis (hazard ratio=1.06; P=0.69). Peak inspiratory pressure of <30 cm H2O was protective against development of PPCs (hazard ratio=0.46; confidence interval: 0.30-0.72; P=0.001). Median FiO2 was 0.5 (IQR: 0.44-0.53), and an increase in FiO2 by 5% increased the risk of developing a PPC by 8% (2.6-14.1%; P=0.008). CONCLUSIONS: Both intraoperative peak inspiratory pressure and FiO2 are independent factors significantly associated with development of a postoperative pulmonary complication in emergency laparotomy patients. Further studies are required to identify causality and to demonstrate if their manipulation could lead to better clinical outcomes.

Left ventricular systolic function evaluated by strain echocardiography and relationship with mortality in patients with severe sepsis or septic shock: a systematic review and meta-analysis.

BACKGROUND: Sepsis-induced myocardial dysfunction is associated with poor outcomes, but traditional measurements of systolic function such as left ventricular ejection fraction (LVEF) do not directly correlate with prognosis. Global longitudinal strain (GLS) utilizing speckle-tracking echocardiography (STE) could be a better marker of intrinsic left ventricular (LV) function, reflecting myocardial deformation rather than displacement and volume changes. We sought to investigate the prognostic value of GLS in patients with sepsis and/or septic shock. METHODS: We conducted a systematic review (PubMed and Embase up to 26 October 2017) and meta-analysis to investigate the association between GLS and mortality at longest follow up in patients with severe sepsis and/or septic shock. In the primary analysis, we included studies reporting transthoracic echocardiography data on GLS according to mortality. A secondary analysis evaluated the association between LVEF and mortality including data from studies reporting GLS. RESULTS: We included eight studies in the primary analysis with a total of 794 patients (survival 68%, n = 540). We found a significant association between worse LV function and GLS values and mortality: standard mean difference (SMD) - 0.26; 95% confidence interval (CI) - 0.47, - 0.04; p = 0.02 (low heterogeneity, I2 = 43%). No significant association was found between LVEF and mortality in the same population of patients (eight studies; SMD, 0.02; 95% CI - 0.14, 0.17; p = 0.83; no heterogeneity, I2 = 3%). CONCLUSIONS: Worse GLS (less negative) values are associated with higher mortality in patients with severe sepsis or septic shock, while such association is not valid for LVEF. More critical care research is warranted to confirm the better ability of STE in demonstrating underlying intrinsic myocardial disease compared to LVEF.

Cost-effectiveness of a quality improvement bundle for emergency laparotomy.

BACKGROUND: The recent Emergency Laparotomy Pathway Quality Improvement Care (ELPQuiC) study showed that the use of a specific care bundle reduced mortality in patients undergoing emergency laparotomy. However, the costs of implementation of the ELPQuiC bundle remain unknown. The aim of this study was to assess the in-hospital and societal costs of implementing the ELPQuiC bundle. METHODS: The ELPQuiC study employed a before-after approach using quality improvement methodology. To assess the costs and cost-effectiveness of the bundle, two models were constructed: a short-term model to assess in-hospital costs and a long-term model (societal decision tree) to evaluate the patient's lifetime costs (in euros). RESULTS: Using health economic modelling and data collected from the ELPQuiC study, estimated costs for initial implementation of the ELPQuiC bundle were €30 026·11 (range 1794·64-40 784·06) per hospital. In-hospital costs per patient were estimated at €14 817·24 for standard (non-care bundle) treatment versus €15 971·24 for the ELPQuiC bundle treatment. Taking a societal perspective, lifetime costs of the patient in the standard group were €23 058·87, compared with €19 102·37 for patients receiving the ELPQuiC bundle. The increased life expectancy of 4 months for patients treated with the ELPQuiC bundle was associated with cost savings of €11 410·38 per quality-adjusted life-year saved. CONCLUSION: Implementation of the ELPQuiC bundle is associated with lower mortality and higher in-hospital costs but reduced societal costs.

Fluid therapy in neurointensive care patients: ESICM consensus and clinical practice recommendations

Objective To report the ESICM consensus and clinical practice recommendations on fluid therapy in neurointensive care patients. Design A consensus committee comprising 22 international experts met in October 2016 during ESICM LIVES2016. Teleconferences and electronic-based discussions between the members of the committee subsequently served to discuss and develop the consensus process. Methods Population, intervention, comparison, and outcomes (PICO) questions were reviewed and updated as needed, and evidence profiles generated. The consensus focused on three main topics: (1) general fluid resuscitation and maintenance in neurointensive care patients, (2) hyperosmolar fluids for intracranial pressure control, (3) fluid management in delayed cerebral ischemia after subarachnoid haemorrhage. After an extensive literature search, the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system were applied to assess the quality of evidence (from high to very low), to formulate treatment recommendations as strong or weak, and to issue best practice statements when applicable. A modified Delphi process based on the integration of evidence provided by the literature and expert opinions­using a sequential approach to avoid biases and misinterpretations­was used to generate the final consensus statement. Results The final consensus comprises a total of 32 statements, including 13 strong recommendations and 17 weak recommendations. No recommendations were provided for two statements. Conclusions We present a consensus statement and clinical practice recommendations on fluid therapy for neurointensive care patients.

Broadband near-infrared astronomical spectrometer calibration and on-sky validation with an electro-optic laser frequency comb.

The quest for extrasolar planets and their characterization as well as studies of fundamental physics on cosmological scales rely on capabilities of high-resolution astronomical spectroscopy. A central requirement is a precise wavelength calibration of astronomical spectrographs allowing for extraction of subtle wavelength shifts from the spectra of stars and quasars. Here, we present an all-fiber, 400 nm wide near-infrared frequency comb based on electro-optic modulation with 14.5 GHz comb line spacing. Tests on the high-resolution, near-infrared spectrometer GIANO-B show a photon-noise limited calibration precision of < 10 cms as required for Earth-like planet detection. Moreover, the presented comb provides detailed insight into particularities of the spectrograph such as detector inhomogeneities and differential spectrograph drifts. The system is validated in on-sky observations of a radial velocity standard star (HD221354) and telluric atmospheric absorption features. The advantages of the system include simplicity, robustness and turn-key operation, features that are valuable at the observation sites.

Tissue Doppler assessment of diastolic function and relationship with mortality in critically ill septic patients: a systematic review and meta-analysis.

BACKGROUND: Myocardial dysfunction may contribute to circulatory failure in sepsis. There is growing evidence of an association between left ventricular diastolic dysfunction (LVDD) and mortality in septic patients. Utilizing echocardiography, we know that tissue Doppler imaging (TDI) variables e' and E/e' are reliable predictors of LVDD and are useful measurements to estimate left ventricular (LV) filling pressures. METHODS: We conducted a systematic review and meta-analysis to investigate the association of e' and E/e' with mortality of patients with severe sepsis or septic shock. In the primary analysis, we included studies providing transthoracic TDI data for e' and E/e' and their association with mortality. Subgroup analyses were conducted according to myocardial regional focus of TDI assessment (septal, lateral or averaged). Three secondary analyses were performed: one included data from a transoesophageal study, another excluded studies reporting data at a very early (<6 h) or late (>48 h) stage following diagnosis, and the third pooled data only from studies excluding patients with heart valve disease. RESULTS: The primary analysis included 16 studies with 1507 patients with severe sepsis and/or septic shock. A significant association was found between mortality and both lower e' [standard mean difference (SMD) 0.33; 95% confidence interval (CI): 0.05, 0.62; P=0.02] and higher E/e' (SMD -0.33; 95% CI: -0.57, -0.10; P=0.006). In the subgroup analyses, only the lateral TDI values showed significant association with mortality (lower e' SMD 0.45; 95% CI: 0.11, 0.78; P=0.009; higher E/e' SMD -0.49; 95% CI: -0.76, -0.22; P=0.0003). The findings of the primary analysis were confirmed by all secondary analyses. CONCLUSIONS: There is a strong association between both lower e' and higher E/e' and mortality in septic patients.

Effects of arterial load variations on dynamic arterial elastance: an experimental study.

BACKGROUND.: Dynamic arterial elastance (Ea dyn ), the relationship between pulse pressure variation (PPV) and stroke volume variation (SVV), has been suggested as a functional assessment of arterial load. The aim of this study was to evaluate the impact of arterial load changes during acute pharmacological changes, fluid administration, and haemorrhage on Ea dyn . METHODS.: Eighteen anaesthetized, mechanically ventilated New Zealand rabbits were studied. Arterial load changes were induced by phenylephrine ( n =9) or nitroprusside ( n =9). Thereafter, animals received a fluid bolus (10 ml kg -1 ), followed by stepwise bleeding (blood loss: 15 ml kg -1 ). The influence of arterial load and cardiac variables on PPV, SVV, and Ea dyn was analysed using a linear mixed-effects model analysis. RESULTS.: After phenylephrine infusion, mean ( sd ) Ea dyn decreased from 0.89 (0.14) to 0.49 (0.12), P <0.001; whereas after administration of nitroprusside, Ea dyn increased from 0.80 (0.23) to 1.28 (0.21), P <0.0001. Overall, the fluid bolus decreased Ea dyn [from 0.89 (0.44) to 0.73 (0.35); P <0.01], and haemorrhage increased it [from 0.78 (0.23) to 0.95 (0.26), P =0.03]. Both PPV and SVV were associated with similar arterial factors (effective arterial elastance, arterial compliance, and resistance) and heart rate. Furthermore, PPV was also related to the acceleration and peak velocity of aortic blood flow. Both arterial and cardiac factors contributed to the evolution of Ea dyn throughout the experiment. CONCLUSIONS.: Acute modifications of arterial load induced significant changes on Ea dyn ; vasodilatation increased Ea dyn , whereas vasoconstriction decreased it. The Ea dyn was associated with both arterial load and cardiac factors, suggesting that Ea dyn should be more properly considered as a ventriculo-arterial coupling index.

Haemodynamic monitoring in the peri-operative period: the past, the present and the future.

Over recent years there has been an increase in the implementation of goal-directed therapy using minimally invasive haemodynamic monitoring techniques to guide peri-operative care. Since the introduction of the pulmonary artery flotation catheter in the 1980s, various haemodynamic monitors have been developed, each associated with their own benefits and limitations. Goal-directed therapy has been well-established as a standard of care in the peri-operative period and has largely been associated with a reduction in morbidity and mortality. However, evidence over the last few years from major studies has led us to question: what is the future for goal-directed therapy? Care of the peri-operative patient has significantly evolved over the last decade and this needs to be taken into account when assessing the results of these studies. We should therefore not look at the effects of goal-directed therapy in isolation but as part of a progressive care bundle. Additionally, other markers of haemodynamic status have also begun to be further appreciated and these are worthy of further investigation. We feel that the future for haemodynamic monitoring remains promising with new areas of interest continuously emerging, but further research is still required.

A randomised controlled trial comparing transnasal humidified rapid insufflation ventilatory exchange (THRIVE) pre-oxygenation with facemask pre-oxygenation in patients undergoing rapid sequence induction of anaesthesia.

Pre-oxygenation is an essential part of rapid sequence induction of general anaesthesia for emergency surgery, in order to increase the oxygen reservoir in the lungs. We performed a randomised controlled trial of transnasal humidified rapid insufflation ventilatory exchange (THRIVE) pre-oxygenation or facemask pre-oxygenation in patients undergoing emergency surgery. Twenty patients were allocated to each group. No patient developed arterial oxygen saturation < 90% during attempted tracheal intubation. Arterial blood gases were sampled from an arterial catheter immediately after intubation. The mean (SD) PaO2 was 43.7 (15.2) kPa in the THRIVE group vs. 41.9 (16.2) kPa in the facemask group (p = 0.722); PaCO2 was 5.8 (1.1) kPa in the THRIVE group vs. 5.6 (1.0) kPa in the facemask group (p = 0.631); arterial pH was 7.36 (0.05) in the THRIVE group vs. 7.34 (0.06) in the facemask group (p = 0.447). No airway rescue manoeuvres were needed, and there were no differences in the number of laryngoscopy attempts between the groups. In spite of this, patients in the THRIVE group had a significantly longer apnoea time of 248 (71) s compared with 123 (55) s in the facemask group (p < 0.001). Transnasal humidified rapid insufflation ventilatory exchange is a practicable method for pre-oxygenating patients during rapid sequence induction of general anaesthesia for emergency surgery; we found that it maintained an equivalent blood gas profile to facemask pre-oxygenation, in spite of a significantly longer apnoea time.

Goal-directed therapy to maintain haemostasis.

Perioperative goal-directed therapy typically involves the use of haemodynamic targets to optimise oxygen delivery. Common goals include stroke volume, cardiac output and arterial blood pressure, although future protocols may also incorporate an assessment of vascular tone and the microcirculation. This article reviews the current evidence for goal-directed therapy and discusses future directions.