Capnodynamic monitoring of lung volume and pulmonary blood flow during alveolar recruitment: a prospective observational study in postoperative cardiac patients.

Alveolar recruitment manoeuvres may mitigate ventilation and perfusion mismatch after cardiac surgery. Monitoring the efficacy of recruitment manoeuvres should provide concurrent information on pulmonary and cardiac changes. This study in postoperative cardiac patients applied capnodynamic monitoring of changes in end-expiratory lung volume and effective pulmonary blood flow. Alveolar recruitment was performed by incremental increases in positive end-expiratory pressure (PEEP) to a maximum of 15 cmH2O from a baseline of 5 cmH2O over 30 min. The change in systemic oxygen delivery index after the recruitment manoeuvre was used to identify responders (> 10% increase) with all other changes (≤ 10%) denoting non-responders. Mixed factor ANOVA using Bonferroni correction for multiple comparisons was used to denote significant changes (p < 0.05) reported as mean differences and 95% CI. Changes in end-expiratory lung volume and effective pulmonary blood flow were correlated using Pearson's regression. Twenty-seven (42%) of 64 patients were responders increasing oxygen delivery index by 172 (95% CI 61-2984) mL min-1 m-2 (p < 0.001). End-expiratory lung volume increased by 549 (95% CI 220-1116) mL (p = 0.042) in responders associated with an increase in effective pulmonary blood flow of 1140 (95% CI 435-2146) mL min-1 (p = 0.012) compared to non-responders. A positive correlation (r = 0.79, 95% CI 0.5-0.90, p < 0.001) between increased end-expiratory lung volume and effective pulmonary blood flow was only observed in responders. Changes in oxygen delivery index after lung recruitment were correlated to changes in end-expiratory lung volume (r = 0.39, 95% CI 0.16-0.59, p = 0.002) and effective pulmonary blood flow (r = 0.60, 95% CI 0.41-0.74, p < 0.001). Capnodynamic monitoring of end-expiratory lung volume and effective pulmonary blood flow early in postoperative cardiac patients identified a characteristic parallel increase in both lung volume and perfusion after the recruitment manoeuvre in patients with a significant increase in oxygen delivery.Trial registration This study was registered on ClinicalTrials.gov (NCT05082168, 18th of October 2021).

A prospective, observational study of cerebrovascular autoregulation and its association with delirium following cardiac surgery.

This aim of this prospective observational cohort study was to evaluate any association between postoperatively impaired cerebrovascular autoregulation and the onset of delirium following cardiac surgery. Previous studies have shown that impaired intra-operative cerebrovascular autoregulation during cardiopulmonary bypass is associated with delirium. However, postoperative changes in cerebrovascular autoregulation and its association with delirium have not been investigated. One-hundred and eight consecutive adult cardiac surgical patients without baseline cognitive dysfunction or aphasia were included in the study. Cerebrovascular autoregulation was assessed by the Pearson correlation between near-infrared spectroscopy-derived cerebral tissue oxygen saturation and mean arterial pressure to derive the tissue oximetry index. Cerebrovascular autoregulation was monitored for a minimum of 90 min on postoperative day 0 and postoperative day 1. Delirium was assessed throughout intensive care unit admission using the confusion assessment method for the intensive care unit. We observed delirium in 24 of the 108 patients studied. The mean (SD) tissue oximetry index was higher in delirious patients on postoperative day 0 compared with non-delirious patients; 0.270 (0.199) vs. 0.180 (0.142), p = 0.044, but not on postoperative day 1; 0.130 (0.160) vs. 0.150 (0.130), p = 0.543. All patients showed improvement in tissue oximetry index on postoperative day 1 compared with postoperative day 0. Logistic regression analysis demonstrated tissue oximetry index on postoperative day 0 to be independently associated with delirium; odds ratio 1.05 (95%CI 1.01-1.10), p = 0.043. In conclusion, we found an association between impaired cerebrovascular autoregulation, measured by near-infrared spectroscopy, and delirium in the early postoperative period.

Cerebrovascular autoregulation monitoring and patient-centred outcomes after cardiac surgery: a systematic review.

BACKGROUND: Impaired cerebrovascular autoregulation (CVAR) is observed in up to 20% of cardiac surgical patients. This systematic review aims to evaluate the association between impaired CVAR, measured by current monitoring techniques, and patient-centred outcomes in adults following cardiac surgery. METHODS: MEDLINE, EMBASE, PubMed, MEDLINE In-Process and Cochrane Library were systematically searched through 8 December 2017. Studies were included if they assessed associations between CVAR and patient-centred outcomes in the adult cardiac surgical population. The primary outcome of this systematic review was mortality. Secondary outcomes were stroke, delirium and acute kidney injury. Risk of bias was systematically assessed, and the GRADE methodology was used to evaluate the quality of evidence across outcomes. RESULTS: Eleven observational studies and no randomised controlled trials met the inclusion criteria. Due to methodological heterogeneity, meta-analysis was not possible. There was a high risk of bias within individual studies and low quality of evidence across outcomes. Of the included studies, one assessed mortality, five assessed stroke, four assessed delirium, and three assessed acute kidney injury. No reliable conclusions can be drawn from the one study assessing mortality. Interpretation of studies investigating CVAR and stroke, delirium and acute kidney injury was complicated by the lack of standardisation of monitoring techniques as well as varying definitions of impaired CVAR. CONCLUSIONS: There is a paucity of high quality evidence for CVAR monitoring and its associations with outcome measures in post-cardiac surgical patients, highlighting the need for future studies.

Corticosteroids and risk of gastrointestinal bleeding in critically ill adults: Protocol for a systematic review.

BACKGROUND: Corticosteroids are frequently prescribed to critically ill patients. However, their use may increase the risk of gastrointestinal (GI) bleeding, which is associated with morbidity and mortality. Accordingly, we aim to assess whether continued administration of corticosteroids for >24 hours increases the rate of GI bleeding in adult critically ill patients compared to placebo or no treatment. METHODS/DESIGN: We will conduct a systematic review of randomized clinical trials with meta-analysis and trial sequential analysis. The participants will be adult (as defined in the included trials) critically ill patients. The intervention will be any corticosteroid administered systematically for >24 hours and the comparator will be placebo or no treatment. The primary outcome will be rate of clinically important GI bleeding. We will systematically search EMBASE, MEDLINE, Medline In-Process, Cochrane Library, Epistemonikos and trial registries for relevant literature, as well as perform a hand search. We will follow the recommendations by the Cochrane Collaboration and the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. The risk of systematic errors (bias) and random errors will be assessed and the overall quality of evidence will be evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. DISCUSSION: The risk of GI bleeding in adult critically ill patients treated with corticosteroids is unknown. Hence, there is need for a robust systematic review to assess this risk and provide clinicians with a clearer understanding of the strength and limitations of existing data.

Lactate, lactate clearance and outcome after cardiac arrest: A post-hoc analysis of the TTM-Trial.

BACKGROUND: Admission lactate and lactate clearance are implemented for risk stratification in sepsis and trauma. In out-of-hospital cardiac arrest, results regarding outcome and lactate are conflicting. METHODS: This is a post-hoc analysis of the Target Temperature Management trial in which 950 unconscious patents after out-of-hospital cardiac arrest were randomized to a temperature intervention of 33°C or 36°C. Serial lactate samples during the first 36 hours were collected. Admission lactate, 12-hour lactate, and the clearance of lactate within 12 hours after admission were analyzed and the association with 30-day mortality assessed. RESULTS: Samples from 877 patients were analyzed. In univariate logistic regression analysis, the odds ratio for death by day 30 for each mmol/L was 1.12 (1.08-1.16) for admission lactate, P < .01, 1.21 (1.12-1.31) for 12-hour lactate, P < .01, and 1.003 (1.00-1.01) for each percentage point increase in 12-hour lactate clearance, P = .03. Only admission lactate and 12-hour lactate levels remained significant after adjusting for known predictors of outcome. The area under the receiver operating characteristic curve was 0.65 (0.61-0.69), P < .001, 0.61 (0.57-0.65), P < .001, and 0.53 (0.49-0.57), P = .15 for admission lactate, 12-hour lactate, and 12-hour lactate clearance, respectively. CONCLUSIONS: Admission lactate and 12-hour lactate values were independently associated with 30-day mortality after out-of-hospital cardiac arrest while 12-hour lactate clearance was not. The clinical value of lactate as the sole predictor of outcome after out-of-hospital cardiac arrest is, however, limited.

Volume responsiveness assessed by passive leg raising and a fluid challenge: a critical review focused on mean systemic filling pressure.

This review applied cardiovascular principles relevant to the physiology of venous return in interpreting studies on the utility of a passive leg-raising manoeuvre to identify patients who do (responders) or do not respond to a subsequent intravenous volume challenge with an increase in cardiac output. Values for cardiac output, mean arterial and central venous pressure, and the calculated cardiovascular variables mean systemic filling pressure analogue, heart efficiency, cardiac power indexed by volume state and volume efficiency, before and after passive leg raising as well as before and after fluid volume challenge, were extracted from published studies. Eleven studies including 572 patients and 52% responders were analysed. Cardiac output increased by 12% in responders during passive leg raising and by 22% following a volume challenge. No statistically significant differences were found between responders and non-responders in cardiac output, mean arterial or central venous pressure before the passive leg-raising manoeuvre or the volume challenge. In contrast, the calculated mean (SD) systemic filling pressure analogue, reflecting the intravascular volume, was significantly lower in responders (14.2 (1.8) mmHg) than non-responders (17.5 (3.4) mmHg; p = 0.007) before the passive leg-raising manoeuvre, as well as before fluid volume challenge (14.6 (2.2) mmHg vs. 17.6 (3.5) mmHg, respectively; p = 0.02). The scalar measure volume efficiency was higher in responders at 0.35 compared with non-responders at 0.10. Non-responders also demonstrated deteriorating heart efficiency of -15% and cardiac power of -7% when given an intravenous fluid volume challenge. The results demonstrate that the calculation of mean systemic filling pressure analogue and derived variables can identify patients likely to respond to a fluid volume challenge and provides scalar results rather than merely a dichotomous outcome of responder or non-responder.

Carotid Doppler flowmetry correlates poorly with thermodilution cardiac output following cardiac surgery.

BACKGROUND: It remains unclear whether measuring carotid arterial flow by the time velocity integral using vascular Doppler ultrasound can be used to monitor cardiac output and volume responsiveness. METHODS: The carotid Doppler flow (time velocity integral and peak flow velocity variation) was assessed in triplicate by an intensivist with formal vascular ultrasound training. Thirty-three patients admitted following coronary by-pass surgery were studied before and after a passive leg-raising manoeuvre to investigate volume responsiveness (more than 10% increase in cardiac output) along with indices of arterial load measuring cardiac output by thermodilution. Pearson's correlation coefficient and area under the curve (AUC) by receiver operating characteristics were calculated. RESULTS: A significant correlation between carotid Doppler flow and cardiac output was demonstrated in post-operative cardiac surgery patients (r = 0.80 [95%CI 0.61-0.89]), including relative changes following passive leg raising (r = 0.79 [95%CI 0.60-0.89]) that showed a mean difference of 2% with wide limits of agreements (-19% to 16%). Changes in carotid Doppler flow following passive leg raising correlated with the baseline arterial resistance but not with compliance or effective elastance. A peak flow variation > 10% before passive leg raising discriminated responders to the manoeuvre with an AUC of 0.81 [95% CI 0.55-0.95]. CONCLUSIONS: Weak correlations between common carotid Doppler flow and cardiac output mean that the methods cannot be used interchangeably in post-operative cardiac surgery patients.

Shock treatment in a cohort of Scandinavian intensive care units in 2014.

BACKGROUND: Shock is common in intensive care units, and treatment includes fluids, vasopressor and/or inotropic drugs, guided by hemodynamic monitoring. The aim of this study was to identify current practice for treatment of shock in Scandinavian intensive care units. METHODS: Seven-day inception cohort study in 43 intensive care units in Scandinavia. Patients ≥ 15 years old receiving more than 4 h of cardiovascular acting drug infusion were included. The use of fluids, vasopressor and inotropic drugs, type of monitoring, and target values were recorded. RESULTS: One hundred and seventy-one patients were included. At inclusion, 136/168 (81%) had received vasopressor and/or inotropic drug therapy for less than 24 h, and 143/171 (84%) had received volume loading before the onset of vasoactive drug treatment. Ringer's solution was given to 129/143 (90%) of patients and starches in 3/143 (2%) patients. Noradrenaline was the most commonly used cardiovascular acting drug, given in 168/171 (98%) of cases while dopamine was rarely used. Mean arterial pressure was considered the most important variable for hemodynamic monitoring. Invasive arterial blood pressure was monitored in 166/171 (97%) of patients, arterial pulse wave analysis in 11/171 (7%), and echocardiography in 50/171 (29%). CONCLUSION: In this survey, Ringer's solution and noradrenaline were the most common first-line treatments in shock. The use of starches and dopamine were rare. Almost all patients were monitored with invasive arterial blood pressure, but comprehensive hemodynamic monitoring was used only in a minority of patients.

Central venous pressure: we need to bring clinical use into physiological context.

BACKGROUND: The place of central venous pressure (CVP) measurement in acute care has been questioned during the past decade. We reviewed its physiological importance, utility and clinical use among anaesthetists and intensivists. METHODS: A literature search using the PubMed, Cochrane, Scopus and Web of Science databases was performed in regard to details of the physiology, measurement and interpretation of CVP. A questionnaire was conducted among members of the European Society of Intensive Care Medicine concerning knowledge and uses of CVP. RESULTS: Aligning pressure transducers to the phlebostatic axis was handled inadequately. The unsuitability of CVP to assess the intravascular volume state was generally recognised by clinicians. Still, many used CVP to guide volume resuscitation in the absence of a cardiac output monitor, while the literature positioned CVP as a useful haemodynamic variable only in the expanded context of being one determinant of the driving pressure for venous return and hence cardiac output. CONCLUSION: The correct measurement of CVP is pivotal to its proper clinical application. This relates to defining the pressure gradient for venous return and heart efficiency. The clinical appreciation of CVP should be restored by educational efforts of its physiological context.

Early screening to identify patients at risk of developing intra-abdominal hypertension and abdominal compartment syndrome.

BACKGROUND: To develop a screening tool to identify patients at risk of developing intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) within 24 h of a patient's admission to intensive care unit (ICU). METHODS: Prospective, observational study of 403 consecutively enrolled patients with an indwelling catheter, admitted to a mixed medical-surgical ICU in a tertiary referral, university hospital. Intra-abdominal pressure was measured at least twice daily and IAH and ACS defined as per consensus definitions. RESULTS: Thirty-nine per cent of patients developed IAH and 2% developed ACS. Abdominal distension, hemoperitoneum/pneumoperitoneum/intra-peritoneal fluid collection, obesity, intravenous fluid received > 2.3 l, abbreviated Sequential Organ Failure Assessment score > 4 points and lactate > 1.4 mmol/l were identified as independent predictors of IAH upon admission to ICU. The presence of three or more of these risk factors at admission identified patients that would develop IAH with a sensitivity of 75% and a specificity of 76%, the development of grades II, III and IV IAH with a sensitivity of 91% and a specificity of 62%. Patients that developed IAH required a significantly longer duration of mechanical ventilation and ICU care. Patients that developed grades II-IV IAH had a significantly higher rate of ICU mortality. CONCLUSION: IAH is a common clinical entity in the intensive care setting that is associated with morbidity and mortality. A screening tool, based on data readily available within a patient's first 24 h in ICU, was developed and effectively identified patients that required intra-abdominal pressure monitoring.

The future role of the Scandinavian anaesthesiologist: a web-based survey.

BACKGROUND: The Board of the Scandinavian Society for Anaesthesiology and Intensive Care Medicine (SSAI) decided in 2008 to undertake a survey among members of the SSAI aiming at exploring some key points of training, professional activities and definitions of the specialty. METHODS: A web-based questionnaire was used to capture core data on workforce demographics and working patterns together with opinions on definitions for practice/practitioners in the four areas of anaesthesia, intensive care medicine, emergency medicine and pain medicine. RESULTS: One thousand seven hundred and four responses were lodged, representing close to half of the total SSAI membership. The majority of participants reported in excess of 10 years of professional experience in general anaesthesia and intensive care medicine as well as emergency and pain medicine. While no support for separate or secondary specialities in the four areas was reported, a majority of respondents favoured sub-specialisation or recognition of particular medical competencies, notably so for intensive care medicine. Seventy-five percent or more of the respondents supported a common framework of employment within all four areas irrespective of further specialisation. CONCLUSIONS: The future of Scandinavian anaesthesiology is likely to involve further specialisation towards particular medical competencies. With such diversification of the workforce, the majority of the respondents still acknowledge the importance of belonging to one organisational body.

Shaping the future of Scandinavian anaesthesiology: a position paper by the SSAI.

Traditionally, Scandinavian anaesthesiologists have had a very broad scope of practice, involving intensive care, pain and emergency medicine. European changes in the different medical fields and the constant reorganising of health care may alter this. Therefore, the Board of the Scandinavian Society of Anaesthesiology and Intensive Care Medicine (SSAI) decided to produce a Position Paper on the future of the speciality in Scandinavia. The training in the various Scandinavian countries is very similar and provides a stable foundation for the speciality. The Scandinavian practice in anaesthesia and intensive care is based on a team model where the anaesthesiologists work together with highly educated nurses and should remain like this. However, SSAI thinks that the role of the anaesthesiologists as perioperative physicians is not fully developed. There is an obvious need and desire for further training of specialists. The SSAI advanced educational programmes for specialists should be expanded and include formal assessment leading to a particular medical competency as defined by the European Union of Medical Specialists (UEMS). In this way, Scandinavian anaesthesiologists will remain leaders in perioperative, intensive care, pain and critical emergency medicine.

Airway management during in-hospital cardiac arrest: An international, multicentre, retrospective, observational cohort study.

AIM: To determine the type of airway devices used during in-hospital cardiac arrest (IHCA) resuscitation attempts. METHODS: International multicentre retrospective observational study of in-patients aged over 18 years who received chest compressions for cardiac arrest from April 2016 to September 2018. Patients were identified from resuscitation registries and rapid response system databases. Data were collected through review of resuscitation records and hospital notes. Airway devices used during cardiac arrest were recorded as basic (adjuncts or bag-mask), or advanced, including supraglottic airway devices, tracheal tubes or tracheostomies. Descriptive statistics and multivariable regression modelling were used for data analysis. RESULTS: The final analysis included 598 patients. No airway management occurred in 36 (6%), basic airway device use occurred at any time in 562 (94%), basic airway device use without an advanced airway device in 182 (30%), tracheal intubation in 301 (50%), supraglottic airway in 102 (17%), and tracheostomy in 1 (0.2%). There was significant variation in airway device use between centres. The intubation rate ranged between 21% and 90% while supraglottic airway use varied between 1% and 45%. The choice of tracheal intubation vs. supraglottic airway as the second advanced airway device was not associated with immediate survival from the resuscitation attempt (odds ratio 0.81; 95% confidence interval 0.35-1.8). CONCLUSION: There is wide variation in airway device use during resuscitation after IHCA. Only half of patients are intubated before return of spontaneous circulation and many are managed without an advanced airway. Further investigation is needed to determine optimal airway device management strategies during resuscitation following IHCA.

Monitoring pulmonary perfusion by electrical impedance tomography: an evaluation in a pig model.

BACKGROUND: Electrical impedance tomography (EIT) is a non-invasive technique that generates images of impedance distribution. Changes in the pulmonary content of air and blood are major determinants of thoracic impedance. This study was designed to evaluate EIT in monitoring pulmonary perfusion in a wide range of cardiac output. METHODS: Eight anaesthetised, mechanically ventilated pigs were fitted with a 16-electrode belt at the mid-thoracic level to generate EIT images that were analysed to determine pulse-synchronous systolic changes in impedance (DeltaZ(sys)). Stroke volume (SV) was derived using a pulmonary artery catheter. Reductions in cardiac pre-load, and thus pulmonary perfusion, were induced either by inflating the balloon of a Fogarty catheter positioned in the inferior caval vein or by increasing the positive end-expiratory pressure (PEEP). All measurements were performed in a steady state during a short apnoea. RESULTS: Pulse-synchronous changes in DeltaZ(sys) were easily discernable during apnoea. Balloon inflation reduced SV to 36% of the baseline, with a corresponding decrease in DeltaZ(sys) to 45% of baseline. PEEP reduced SV and DeltaZ(sys) to 52% and 44% of the baseline, respectively. Significant correlations between SV and DeltaZ(sys) were demonstrated during all measurements (rho=0.62) as well as during balloon inflation (rho=0.73) and increased PEEP (rho=0.40). A Bland-Altman comparison of relative changes in SV and DeltaZ(sys) demonstrated a bias of -7%, with 95% limits of agreement at -51% and 36%. CONCLUSIONS: EIT provided beat-to-beat approximations of pulmonary perfusion that significantly correlated to a wide range of SV values achieved during both extra and intrapulmonary interventions to change cardiac output.

A Scandinavian survey of drug administration through inhalation, suctioning and recruitment maneuvers in mechanically ventilated patients.

BACKGROUND: The aim was to describe current practices for drug administration through inhalation, endotracheal suctioning and lung recruitment maneuvers in mechanically ventilated patients in Scandinavian intensive care units (ICUs). METHODS: We invited 161 ICUs to participate in a web-based survey regarding (1) their routine standards and (2) current treatment of ventilated patients during the past 24 h. In order to characterize the patients, the lowest PaO(2) with the corresponding highest FiO(2), and the highest PaO(2) with the corresponding lowest FiO(2) during the 24-h study period were recorded. RESULTS: Eighty-seven ICUs answered and reported 186 patients. Positive end-expiratory pressure (PEEP) levels (cmH(2)O) were 5-9 in 65% and >10 in 31% of the patients. Forty percent of the patients had heated humidification and 50% received inhalation of drugs. Endotracheal suctioning was performed >7 times during the study period in 40% of the patients, of which 23% had closed suction systems. Twenty percent of the patients underwent recruitment maneuvers. The most common recruitment maneuver was to increase PEEP and gradually increase the inspiratory pressure. Twenty-six percent of the calculated PaO(2)/FiO(2) ratios varied >13 kPa for the same patient. CONCLUSION: Frequent use of drug administration through inhalation and endotracheal suctioning predispose to derecruitment of the lungs, possibly resulting in the large variations in PaO(2)/FiO(2) ratios observed during the 24-h study period. Recruitment maneuvers were performed only in one-fifth of the patients during the day of the survey.

Electrical impedance tomography and heterogeneity of pulmonary perfusion and ventilation in porcine acute lung injury.

BACKGROUND: The heterogeneity of pulmonary ventilation (V), perfusion (Q) and V/Q matching impairs gas exchange in an acute lung injury (ALI). This study investigated the feasibility of electrical impedance tomography (EIT) to assess the V/Q distribution and matching during an endotoxinaemic ALI in pigs. METHODS: Mechanically ventilated, anaesthetised pigs (n=11, weight 30-36 kg) were studied during an infusion of endotoxin for 150 min. Impedance changes related to ventilation (Z(V)) and perfusion (Z(Q)) were monitored globally and bilaterally in four regions of interest (ROIs) of the EIT image. The distribution and ratio of Z(V) and Z(Q) were assessed. The alveolar-arterial oxygen difference, venous admixture, fractional alveolar dead space and functional residual capacity (FRC) were recorded, together with global and regional lung compliances and haemodynamic parameters. Values are mean+/-standard deviation (SD) and regression coefficients. RESULTS: Endotoxinaemia increased the heterogeneity of Z(Q) but not Z(V). Lung compliance progressively decreased with a ventral redistribution of Z(V). A concomitant dorsal redistribution of Z(Q) resulted in mismatch of global (from Z(V)/Z(Q) 1.1+/-0.1 to 0.83+/-0.3) and notably dorsal (from Z(V)/Z(Q) 0.86+/-0.4 to 0.51+/-0.3) V and Q. Changes in global Z(V)/Z(Q) correlated with changes in the alveolar-arterial oxygen difference (r(2)=0.65, P<0.05), venous admixture (r(2)=0.66, P<0.05) and fractional alveolar dead space (r(2)=0.61, P<0.05). Decreased end-expiratory Z(V) correlated with decreased FRC (r(2)=0.74, P<0.05). CONCLUSIONS: EIT can be used to assess the heterogeneity of regional pulmonary ventilation and perfusion and V/Q matching during endotoxinaemic ALI, identifying pivotal pathophysiological changes.

Tezosentan normalizes hepatomesenteric perfusion in a porcine model of cardiac tamponade.

BACKGROUND: To investigate endothelin-1 (ET-1)-dependent hepatic and mesenteric vasoconstriction, and oxygen and lactate fluxes in an acute, fixed low cardiac output (CO) state. METHODS: Sixteen anesthetized, mechanically ventilated pigs were studied. Cardiac tamponade was established to reduce portal venous blood flow (Q(PV)) to 2/3 of the baseline value. CO, hepatic artery blood flow (Q(HA)), Q(PV), hepatic laser-Doppler flow (LDF), hepatic venous and portal pressure, and hepatic and mesenteric oxygen and lactate fluxes were measured. Hepatic arterial (R(HA)), portal (R(HP)) and mesenteric (R(mes)) vascular resistances were calculated. The combined ET(A)-ET(B) receptor antagonist tezosentan (RO 61-0612) or normal saline vehicle was infused in the low CO state. Measurements were made at baseline, after 30, 60, 90 min of tamponade, and 30, 60, 90 min following the infusion of tesozentan at 1 mg/kg/h. RESULTS: Tamponade decreased CO, Q(PV), Q(HA), LDF, hepatic and mesenteric oxygen delivery, while hepatic and mesenteric oxygen extraction and lactate release increased. R(HA), R(HP) and R(mes) all increased. Ninety minutes after tesozentan, Q(PV), LDF and hepatic and mesenteric oxygen delivery and extraction increased approaching baseline values, but no effect was seen on CO or Q(HA). Hepatic and mesenteric handling of lactate converted to extraction. R(HA), R(HP) and R(mes) returned to baseline values. No changes were observed in these variables among control animals not receiving tesozentan. CONCLUSION: In a porcine model of acute splanchnic hypoperfusion, unselective ET-1 blockade restored hepatomesenteric perfusion and reversed lactate metabolism. These observations might be relevant when considering liver protection in low CO states.

Fluid therapy in acute myocardial infarction: evaluation of predictors of volume responsiveness.

BACKGROUND: Static vascular filling pressures suffer from poor predictive power in identifying the volume-responsive heart. The use of dynamic arterial pressure variables, including pulse pressure variation (PPV) has instead been suggested to guide volume therapy. The aim of the present study was to evaluate the performance of several clinically applicable haemodynamic parameters to predict volume responsiveness in a pig closed chest model of acute left ventricular myocardial infarction. METHODS: Fifteen anaesthetized, mechanically ventilated pigs were studied following acute left myocardial infarction by temporary coronary occlusion. Animals were instrumented to monitor central venous (CVP) and pulmonary artery occlusion (PAOP) pressures and arterial systolic variations (SPV) and PPV. Cardiac output (CO) was measured using the pulmonary artery catheter and by using the PiCCO monitor also giving stroke volume variation (SVV). Variations in the velocity time integral by pulsed-wave Doppler echocardiography were determined in the left (DeltaVTI(LV)) and right (DeltaVTI(RV)) ventricular outflow tracts. Consecutive boluses of 4 ml/kg hydroxyethyl starch were administered and volume responsiveness was defined as a 10% increase in CO. RESULTS: Receiver-operator characteristics (ROC) demonstrated the largest area under the curve for DeltaVTI(RV) [0.81 (0.70-0.93)] followed by PPV [0.76 (0.64-0.88)] [mean (and 95% CI)]. SPV, DeltaVTI(LV) and SVV did not change significantly during volume loading. CVP and PAOP increased but did not demonstrate significant ROC. CONCLUSION: PPV may be used to predict the response to volume administration in the setting of acute left ventricular myocardial infarction.

Paediatric Rapid Response Systems: a literature review.

BACKGROUND: Paediatric cardiorespiratory arrest carries a poor prognosis. The most common cause is respiratory insufficiency or hypotension/shock, which can be reversible. The use of RRSs in adult hospitals that proactively intervene when signs of physiological instability occur is widespread and increasing although the level of evidence for their efficiency is a matter of debate. METHODS: A systematic literature review was undertaken to evaluate and summarise the current knowledge about paediatric RRSs. RESULTS: Paediatric RRSs are in use in several places around the world. One study shows a statistically significant decrease in mortality rate after implementation. Two studies show a non-significant association with decreased mortality rate. Cardiac and/or respiratory arrest rates decreased in all four before-after studies with statistical significance in two. CONCLUSIONS: Cardiac arrest and death are rare in paediatric hospitals, which can in part explain the difficulties to demonstrate statistically significant benefits. There are also specific problems regarding calling criteria due to age related physiological diversity as well as chronic disease.