Early identification of shock in critically ill patients

Role of artificial intelligence in critical care nutrition support and research

Nutrition plays a key role in the comprehensive care of critically ill patients. Determining optimal nutrition strategy, however, remains a subject of intense debate. Artificial intelligence (AI) applications are becoming increasingly common in medicine, and specifically in critical care, driven by the data-rich environment of intensive care units. In this review, we will examine the evidence regarding the application of AI in critical care nutrition. As of now, the use of AI in critical care nutrition is relatively limited, with its primary emphasis on malnutrition screening and tolerance of enteral nutrition. Despite the current scarcity of evidence, the potential for AI for more personalized nutrition management for critically ill patients is substantial. This stems from the ability of AI to integrate multiple data streams reflecting patients' changing needs while addressing inherent heterogeneity. The application of AI in critical care nutrition holds promise for optimizing patient outcomes through tailored and adaptive nutrition interventions. A successful implementation of AI, however, necessitates a multidisciplinary approach, coupled with careful consideration of challenges related to data management, financial aspects, and patient privacy.

Assessment of changes in blood volume during lower body negative pressure-induced hypovolemia using bioelectrical impedance analysis

BACKGROUND

Lower body negative Pressure (LBNP)-induced hypovolemia is simulating acute hemorrhage by sequestrating blood into lower extremities. Bioelectrical Impedance Analysis (BIA) is based on the electrical properties of biological tissues, as electrical current flows along highly conductive body tissues (such as blood). Changes in blood volume will lead to changes in bioimpedance. This study aims to study changes in upper (UL) and lower (LL) extremities bioimpedance during LBNP-induced hypovolemia.

METHODS

This was a prospective observational study of healthy volunteers who underwent gradual LBNP protocol which consisted of 3-minute intervals: at baseline, -15, -30, -45, -60 mmHg, then recovery phases at -30 mmHg and baseline. The UL&LL extremities bioimpedance were measured and recorded at each phase of LBNP and the percentage changes of bioimpedance from baseline were calculated and compared using student's t-test. A P-value of < 0.05 was considered significant. Correlation between relative changes in UL&LL bioimpedance and estimated blood loss (EBL) from LBNP was calculated using Pearson correlation.

RESULTS

26 healthy volunteers were enrolled. As LBNP-induced hypovolemia progressed, there were a significant increase in UL bioimpedance and a significant decrease in LL bioimpedance. During recovery phases (where blood was shifted from the legs to the body), there were a significant increase in LL bioimpedance and a reduction in UL bioimpedance. There were significant correlations between estimated blood loss from LBNP model with UL (R = 0.97) and LL bioimpedance (R = - 0.97).

CONCLUSION

During LBNP-induced hypovolemia, there were reciprocal changes in UL&LL bioimpedance. These changes reflected hemodynamic compensatory mechanisms to hypovolemia.

DEVELOPMENT OF SCORE SYSTEM BASED ON POINT-OF-CARE ULTRASOUND TO PREDICT VASOPRESSOR REQUIREMENT FOR EMERGENCY PATIENTS WITH CARDIOPULMONARY SYMPTOMS

ABSTRACT

Objectives : Patients with cardiopulmonary symptoms admitted to the emergency department (ED) have high mortality and intensive care unit admission rates. We developed a new scoring system comprising concise triage information, point-of-care ultrasound, and lactate levels to predict vasopressor requirements. Methods : This retrospective observational study was conducted at a tertiary academic hospital. Patients with cardiopulmonary symptoms who visited the ED and underwent point-of-care ultrasound between January 2018 and December 2021 were enrolled. The influence of demographic and clinical findings on the requirement for vasopressor support within 24 h of ED admission was investigated. A new scoring system was developed using key components after stepwise multivariable logistic regression analysis. Prediction performance was evaluated using the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Results : A total of 2,057 patients were analyzed. A stepwise multivariable logistic regression model showed high predictive performance in the validation cohort (AUC, 0.87). Eight key components were selected: hypotension, chief complaint, and fever at ED admission, and way of ED visit, systolic dysfunction, regional wall motion abnormalities, inferior vena cava status, and serum lactate level. The scoring system was developed based on the β coefficients of each component: accuracy, 0.8079; sensitivity, 0.8057; specificity, 0.8214; PPV, 0.9658; and NPV, 0.4035, with a cutoff value according to the Youden index. Conclusions : A new scoring system was developed to predict vasopressor requirements in adult ED patients with cardiopulmonary symptoms. This system can serve as a decision-support tool to guide efficient assignment of emergency medical resources.

Clinical Study of a New Modified Early Warning Scoring System for Rapidly Evaluating Shock in Adults

BACKGROUND

Shock is one of the most common severe syndromes requiring emergency treatment. Acute myocardial infarction guidelines, the surviving sepsis campaign, and low blood volume resuscitation guidelines indicate the prioritization of early identification of shock. APACHE II (Acute Physiology and Chronic Health Evaluation II), SOFA (Sequential Organ Failure Assessment), and MEWS (Modified Early Warning System) scores are used to predict mortality in ICU (intensive care unit) patients. However, similar to APACHE II, SOFA cannot be used for rapid assessment. Hence the need for a new scoring system that is simple, faster, and efficacious in predicting and preventing mortality among shock patients. The present study was conducted to evaluate a new MEWS scoring system for early identification and estimate mortality risk in patients with shock.

METHODS

A total of 170 patients with shock meeting the inclusion criteria who presented to the ICU of Ramaiah Hospitals from November 2019 to August 2021 were included in the study. Baseline variables, laboratory parameters, APACHE II score, SOFA score, MEWS score, and new MEWS score were compared between the two groups. Patients were followed up till mortality or discharge from ICU.

RESULTS

Among the 170 patients included in the study septic shock (69.4%) was the most common type of shock followed by cardiogenic (7.64%) and hypovolemic shock (7.64%). The requirement of inotropic support and mechanical ventilation was associated with significantly higher mortality (55.6% and 52.6% respectively). The AUROC (area under the curve) for SOFA in predicting mortality was 0.738 (p<0.001). The AUROC for APACHE II score in predicting mortality was 0.758 (p<0.001). The AUROC for MEWS score in predicting mortality was 0.655 (p=0.0002). The AUROC for the new MEWS score in predicting mortality was 0.684 which is more than that of the conventional MEWS score (p <0.001).

CONCLUSION

New MEWS score is better than the MEWS score in predicting mortality. The new MEWS score is a simple, entirely clinical, inexpensive scoring system that can be done within a short time as a patient contact in an emergency. Hence, the new MEWS score can help in the quick identification of patients who are at high risk for developing shock and can be used as a better predictor of mortality.

Resuscitation of the Traumatically Injured Patient

Trauma is a leading cause of death. Optimal outcomes depend on a coordinated effort. Providers must be prepared to act in an organized and methodical manner. Recognizing and immediately treating causes of shock after trauma offer the best chance of survival to the patient. Incorporating evidence-based knowledge and resuscitation techniques learned from the military, the trauma victim experiencing acute hypovolemia has better outcomes because of advances in the clinical management of blood loss than ever before. Treatment focuses primarily on stopping the bleeding, providing damage control resuscitation, and monitoring and treating the patient for signs of shock. If the patient can be stabilized and avoid the lethal trauma triad, definitive surgical care can be achieved.

Perfusion Index Analysis in Patients Presenting to the Emergency Department Due to Synthetic Cannabinoid Use

Background and Objectives: The perfusion index (PI) indicates the ratio of pulsatile blood flow in peripheral tissue to non-pulsatile blood flow. This study was performed to examine the blood perfusion status of tissues and organs of patients using synthetic cannabinoids (SCs). Materials and Methods: The records of patients aged 17 or over presenting to the adult emergency department due to SC use between 1 January 2016 and 31 December 2017 were examined in this single-center, retrospective, cross-sectional study. Examined factors included time from consumption of SC to presentation to the emergency department, as well as simultaneously determined systolic and diastolic blood pressures, heart rate (beats per min), Glasgow Coma Score (GCS), and PI values. Patients were divided into two groups, A and B, depending on the amount of time that had elapsed between SC consumption and presentation to the emergency department, and statistical data were compared. Results: The mean PI value in Group A was lower than that in Group B. Therefore, we concluded that peripheral tissue and organ blood perfusion is lower in the first 2 h following SC consumption than after 2 h. Systolic, diastolic, and mean arterial blood pressure and mean GCS values were also statistically significantly lower in Group A than in Group B. Conclusions: A decreased PI value may be an early sign of reduced-perfusion organ damage. PI is a practical and useful parameter in the early diagnosis of impaired organ perfusion and in monitoring tissue hypoxia leading to organ failure.

Assessment of plasma lactate and core-peripheral temperature gradient in association with stages of naturally occurring myxomatous mitral valve disease in dogs

OBJECTIVE

To evaluate plasma lactate concentrations and core-peripheral temperature gradients as perfusion parameters in dogs with heart failure caused by myxomatous mitral valve disease (MMVD) and to determine whether the above perfusion parameters are correlated with disease stages.

DESIGN

Prospective observational study.

SETTING

University teaching hospital.

ANIMALS

After excluding 129 dogs because of exclusion criteria, 7 dogs with heart failure classified as stage B2 and 10 dogs classified as stage C according to the American Heart Association (AHA)/American College of Cardiology (ACC) were included in the study. Six dogs without MMVD were evaluated as the control group.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Among the evaluated parameters, the plasma lactate concentrations were increased in stage C (median 3.70 mmol/L [33.3 mg/dL], interquartile range (IQR) 0.72 mmol/L [6.5 mg/dL]) compared with those in the control (median 2.80 mmol/L [25.2 mg/dL], IQR 0.8 mmol/L [7.2 mg/dL]; P = 0.024) and stage B2 groups (median 2.70 mmol/L [24.3 mg/dL], IQR 1.8 mmol/L [16.2 mg/dL]; P = 0.045). Significant differences were not observed in the core-peripheral temperature gradients among the control, stage B2, and stage C dogs.

CONCLUSIONS

Dogs with structural heart disease as a result of MMVD may have occult tissue hypoperfusion in stage C that is demonstrated by hyperlactatemia.

Reflectance spectroscopy: to shed new light on the capillary refill test

To use Bioengineering methodology is used to achieve, at five anatomical sites, a detailed, quantitative assessment of the return of blood content to the blanched area, during the Capillary Refill (CR) test. An observational, non-randomized, experimental study on 23 healthy subjects (14 females) was performed in our climate controlled skin physiology laboratory. Our main outcome measures were based on the chronological assessment and quantification of red blood cell concentration (RBC) after the release of blanching pressure in the CR test, using Tissue Viability Imaging (TiVi), a digital photographic technique based on polarisation spectroscopy. TiVi enabled collection of detailed data on skin RBC concentration during the CR test. The results were shown as curves with skin blood concentration (TiVi-value) on the y-axis and the time on the x-axis. Quantitative CR responses showed site and temperature variability. We also suggest possible objective endpoint values from the capillary refill curve. Detailed data on skin RBC concentration during the CR test is easily obtained and allows objective determination of end points not possible to achieve by naked eye assessment. These findings have the potential to place the utility of the CR test in a clinical setting in a new light. Picture: Regular photograph and TiVi Image showing CR test and corresponding graph for the CR response.

The Effect of the Emergency Physicians' Clinical Decision of Targeted Ultrasonography Application in Non-Traumatic Shock Patients

Introduction

Clinical evaluation of non-traumatic shock patients with high risk of mortality and morbidity is problematic for emergency physicians. In this study, changes in the investigations, diagnosis and treatment decision of the physicians using the Abdominal and Cardiac Evaluation with Sonography in Shock (ACES) protocol were examined.

Methods

In this clinical prospective study, the patients were ultrasonographically examined within the scope of the ACES protocol at 6 quadrants including cardiac, pleural, peritoneal, inferior vena cava and aorta. Pre- and post-US investigations, diagnoses and treatments were compared.

Results

A total of 141 patients were included in this study. Of these, 92 (65.2%) of the patients were males and 49 (34.8%) were females. The average age of the patients was 62.9±16.8 years (18-97). After the ultrasonographic evaluation, request for new investigations was needed in 25 (17%), and modification of the treatment was needed in 57 (40.4%) of the patients. It was seen that with a targeted ultrasonography (US), the number of the considered pre-diagnoses decreased in 51 (36.2%) of the patients, and the physicians made a new pre-diagnosis in 6 (4.3%) of the patients. When the pre-diagnoses made by the physicians after the US and the final diagnoses clinically made at the end of the follow-up process were compared, there were no changes in the diagnoses in 124 (87.9%) patients.

Conclusion

Ultrasonographic examination is considered useful for rapid evaluation, early diagnosis and treatment planning in non-traumatic shock patients in emergency department. (Hong Kong j.emerg.med. 2015;22:364-370)

Diffuse Reflectance Spectroscopy: Getting the Capillary Refill Test Under One's Thumb

The capillary refill test was introduced in 1947 to help estimate circulatory status in critically ill patients. Guidelines commonly state that refill should occur within 2 s after releasing 5 s of firm pressure (e.g., by the physician's finger) in the normal healthy supine patient. A slower refill time indicates poor skin perfusion, which can be caused by conditions including sepsis, blood loss, hypoperfusion, and hypothermia. Since its introduction, the clinical usefulness of the test has been debated. Advocates point out its feasibility and simplicity and claim that it can indicate changes in vascular status earlier than changes in vital signs such as heart rate. Critics, on the other hand, stress that the lack of standardization in how the test is performed and the highly subjective nature of the naked eye assessment, as well as the test's susceptibility to ambient factors, markedly lowers the clinical value. The aim of the present work is to describe in detail the course of the refill event and to suggest potentially more objective and exact endpoint values for the capillary refill test using diffuse polarization spectroscopy.

Damage Control Resuscitation for Catastrophic Bleeding

The timely recognition of shock secondary to hemorrhage from severe facial trauma or as a complication of complex oral and maxillofacial surgery presents formidable challenges. Specific hemostatic disorders are induced by hemorrhage and several extreme homeostatic imbalances may appear during or after resuscitation. Damage control resuscitation has evolved from massive transfusion to a more complex therapeutic paradigm that includes hemodynamic resuscitation, hemostatic resuscitation, and homeostatic resuscitation. Definitive control of bleeding is the principal objective of any comprehensive resuscitation scheme for hemorrhagic shock.

Muscle oxygenation as an indicator of shock severity in patients with suspected severe sepsis or septic shock

Purpose

The aim of this pilot study was to evaluate the potential of a new noninvasive optical measurement of muscle oxygenation (MOx) to identify shock severity in patients with suspected sepsis.

Methods

We enrolled 51 adult patients in the emergency department (ED) who presented with possible sepsis using traditional Systematic Inflammatory Response Syndrome criteria or who triggered a “Code Sepsis.” Noninvasive MOx measurements were made from the first dorsal interosseous muscles of the hand once potential sepsis/septic shock was identified, as soon as possible after admission to the ED. Shock severity was defined by concurrent systolic blood pressure, heart rate, and serum lactate levels. MOx was also measured in a control group of 17 healthy adults.

Results

Mean (± SD) MOx in the healthy control group was 91.0 ± 5.5% (n = 17). Patients with mild, moderate, and severe shock had mean MOx values of 79.4 ± 21.2%, 48.6 ± 28.6%, and 42.2 ± 4.7%, respectively. Mean MOx for the mild and moderate shock severity categories were statistically different from healthy controls and from each other based on two-sample t-tests (p < 0.05).

Conclusions

We demonstrate that noninvasive measurement of MOx was associated with clinical assessment of shock severity in suspected severe sepsis or septic shock. The ability of MOx to detect even mild septic shock has meaningful implications for emergency care, where decisions about triage and therapy must be made quickly and accurately. Future longitudinal studies may validate these findings and the value of MOx in monitoring patient status as treatment is administered.

Predicting Fluid Responsiveness Using Bedside Ultrasound Measurements of the Inferior Vena Cava and Physician Gestalt in the Emergency Department of an Urban Public Hospital in Sub-Saharan Africa

Background

Bedside inferior vena cava (IVC) ultrasound has been proposed as a non-invasive measure of volume status. We compared ultrasound measurements of the caval index (CI) and physician gestalt to predict blood pressure response in patients requiring intravenous fluid resuscitation.

Methods

This was a prospective study of adult emergency department patients requiring fluid resuscitation. A structured data sheet was used to record serial vital signs and the treating clinician’s impression of patient volume status and cause of hypotension. Bedside ultrasound CI measurements were performed at baseline and after each 500mL of fluid. Receiver operating characteristic (ROC) curve analysis was performed to characterize the relationship between CI and Physician gestalt, and the change in mean arterial pressure (MAP).

Results

We enrolled 364 patients, 52% male, mean age 36 years. Indications for fluid resuscitation were haemorrhage (54%), dehydration (30%), and sepsis (17%). Receiver operating characteristic curve analysis found optimal CI cut-off values of 45%, 52% and 53% to predict a MAP rise of 5, 8 and 10 mmHg per litre of fluid, respectively. The sensitivity and specificity of CI of 50% for predicting a 10mmHg increase in MAP per litre were 88% (95%CI 81–93%) and 73% (95%CI 67–79%), respectively, area under the curve (AUC) = 0.85 (0.81–0.89). The sensitivity and specificity of physician gestalt estimate of volume depletion severity were 68% (95%CI 60–75%) and 86% (95%CI 80–90%), respectively, AUC = 0.83 (95% CI: 0.79–0.87). Those with a baseline CI ≥ 50% (51% of patients) had a 2.8-fold greater fluid responsiveness than those with a baseline CI<50% (p<0.0001).

Conclusion

Ultrasound measurement of the CI can predict blood pressure response among patients requiring intravenous fluid resuscitation and may be useful in early identification of patients who will benefit most from volume resuscitation, and those who will likely require other interventions.

Clinical study of a new Modified Early Warning System scoring system for rapidly evaluating shock in adults

OBJECTIVE

Shock, the most common severe emergency syndrome, has a complicated etiopathogenesis, is difficult to identify, progresses quickly, and is dangerous. Early identification and intervention play determining roles in the final outcomes of shock patients, but no specific scoring system for shock has been established to date.

METHODS

We collected 292 shock patients and analyzed the correlation between 28-day prognosis and the Acute Physiologic Assessment and Chronic Health Evaluation II (APACHE II), Modified Early Warning System (MEWS), and Sequential Organ Failure Assessment scoring systems. According to the previous result, we established a new MEWS scoring system based on the conventional MEWS, which also included age and transcutaneous oxygen saturation. Some of the items with a strong correlation with the 28-day prognosis were selected to establish the new MEWS scoring system. We then evaluated the predictive efficacy of the new MEWS scoring system on 28-day prognosis and the correlation with other scoring systems.

RESULTS

Some indexes, including age, transcutaneous oxygen saturation, arterial blood pH and blood lactic acid, serum sodium, serum potassium, HCO₃, and red blood cells deposited, differed significantly between the nonsurviving and surviving groups (P<.05). The area under the curve (AUC) of the APACHE II, MEWS, shock index, and Sequential Organ Failure Assessment scoring systems for 28-day prognosis indicated a critical predictive efficacy. Receiver operating characteristic curves indicated that the MEWS AUC was 0.614, new MEWS AUC was 0.696, and APACHE II AUC was 0.785, suggesting superiority of the new MEWS to the conventional MEWS but inferiority to the APACHE II. Interestingly, the correlation efficient of the traditional MEWS and the new MEWS was 0.81. The correlation efficient of these scoring systems with other indexes, including lactic acid and hemoglobin, was less than 0.3.

CONCLUSIONS

The new MEWS scoring system could be an independent indicator to reflect shock severity. It has higher predictive efficacy in septic shock, especially for 28-day prognosis.

Fluid management in patients with trauma: Restrictive versus liberal approach

Trauma is a leading cause of death worldwide, and almost 30% of trauma deaths are due to blood loss. A number of concerns have been raised regarding the advisability of the classic principles of aggressive crystalloid resuscitation in traumatic hemorrhagic shock. Some recent studies have shown that early volume restoration in certain types of trauma before definite hemostasis may result in accelerated blood loss, hypothermia, and dilutional coagulopathy. This review discusses the advances and changes in protocols in fluid resuscitation and blood transfusion for treatment of traumatic hemorrhage shock. The concept of low volume fluid resuscitation also known as permissive hypotension avoids the adverse effects of early aggressive resuscitation while maintaining a level of tissue perfusion that although lower than normal, is adequate for short periods. Permissive hypotension is part of the damage control resuscitation strategy, which targets the conditions that exacerbate hemorrhage. The elements of this strategy are permissive hypotension, minimization of crystalloid resuscitation, control of hypothermia, prevention of acidosis, and early use of blood products to minimize coagulopathy.

The impact of using RUSH protocol for diagnosing the type of unknown shock in the emergency department

Clinical assessment and classification of shock is extremely difficult to conduct on critically ill patients especially upon arrival at the emergency department. Resuscitative point-of-care ultrasound could be used for rapid initial diagnosis and better management. In this study, the results of using the RUSH (Rapid Ultrasound in Shock) exam to determine the type of shock in the emergency department are compared to the final diagnosis of patients. This was a single-center prospective study in which all patients with an unknown type of shock and no prior treatment were included. Parallel to the standard resuscitative management and diagnosis of the emergency team, the RUSH exam was performed blindly on the patient by an emergency medicine staff who was not part of the patient's caregiving team. The results of the RUSH exam were then compared to the final diagnosis of the patients and the 48-h outcome. Twenty-five patients were enrolled in this study. The overall kappa correlation of the RUSH exam compared with the final diagnosis was 0.84 which is an almost perfect agreement. The overall sensitivity of the RUSH exam was 88 % and the specificity was 96 %. Although the mortality rate was 64 %, there was not a significant relationship between mortality and the protocol used for diagnosis. The RUSH exam could be used in emergency wards to detect types of shock.

Validating a pragmatic definition of shock in adult patients presenting to the ED

OBJECTIVE

The importance of the early recognition of shock in patients presenting to emergency departments is well recognized, but at present, there is no agreed practical definition for undifferentiated shock. The main aim of this study was to validate an a priori clinical definition of shock against 28-day mortality.

DESIGN, SETTING AND SUBJECTS

This prospective, observational, cross-sectional, single-center study was conducted in Hong Kong, China. Data were collected between July 1, 2012, and January 31, 2013. An a priori definition of shock was designed, whereby patients admitted to the resuscitation room or high dependency area of the emergency department were divided into 1 of 3 groups-no shock, possible shock, and shock. The primary outcome was 28-day mortality. Secondary outcomes were in-hospital mortality or admission to the intensive or coronary care unit.

MEASUREMENTS AND MAIN RESULTS

A total of 111 patients (mean age, 67.2 ± 17.1 years; male = 69 [62%]) were recruited, of which 22 were classified as no shock, 54 as possible shock, and 35 as shock. Systolic blood pressure, mean arterial pressure, lactate, and base deficit correlated well with shock classifications (P < .05). Patients who had 3 or more positively defined shock variables had a 100% poor composite outcome rate (5 of 5). Patients with 2 shock variables had a 66.7% (4 of 6) poor composite outcome rate.

CONCLUSIONS

A simple, practical definition of undifferentiated shock has been proposed and validated in a group of patients presenting to an emergency department in Hong Kong. This definition needs further validation in a larger population and other settings.

Suitability of POC lactate methods for fetal and perinatal lactate testing: considerations for accuracy, specificity and decision making criteria

BACKGROUND

Point of care (POC) testing for fetal scalp blood lactate is a more user friendly and more successful approach compared to scalp pH for intrapartum fetal monitoring. The aim of this study was to assess the analytical specificity and clinical reliability of three POC lactate methods.

METHODS

The analytical performance of three POC lactate methods was compared to Cobas 6000 (Roche Diagnostics) laboratory reference method: Lactate Pro from Arkray, GEM 4000 from Instrumentation Laboratory and StatStrip Lactate from Nova Biomedical. The clinical performance and influences on accuracy and decision making criteria for the three POC methods was assessed with umbilical cord samples and compared to the laboratory reference method. The influence of varying ranges of hemoglobin, pH and partial oxygen pressure (pO(2)) on the accuracy of results was assessed.

RESULTS

Although all three POC methods showed good correlation with the reference method for the umbilical cord sample population (r=0.989, 0.973 and 0.980, respectively), Lactate Pro and Gem 4000 showed a significant negative bias compared to the reference method. The degree of bias meant a significant readjustment of decision making criteria was required for fetal lactate use. The accuracy of the Lactate Pro results was affected by hemoglobin and to a lesser extent pH.

CONCLUSIONS

The three electrochemical POC devices can measure fetal lactate reliably. StatStrip Lactate showed a closer correlation and concordance to our laboratory reference method. The results of this study indicate the requirement for predetermining the reliability of POC lactate methods before use present in fetal and perinatal settings.

A novel hypothesis comprehensively explains shock, heart failure and aerobic exhaustion through an assumed central physiological control of the momentary cardiovascular performance reserve

BACKGROUND

Heart failure (HF) and shock are incomprehensively understood, inconclusively defined and lack a single conclusive test. The proceedings that preceded and triggered clinical manifestations are occult. The relationships in between different shock and HF types and between each HF type and its matched shock are poorly understood.

THE ASSUMED HYPOTHESIS

We suggest that HF and shock are attributed to a momentary cardiovascular performance reserve - "the reserve". The reserve is controlled through an assumed central physiological mechanism that continuously detects and responds accordingly--"the reserve control". The assumed reserve is maximal at rest, and decreases with aerobic activity. When it decreases to a given threshold the reserve control alerts by induces manifestations of dyspnea and fatigue enforcing activity decrease, follow which the manifestations dissolve. HF is a condition of low reserve at baseline; hence, fatigue and dyspnea are frequently experienced following mild activity. Shock is assumed to occur when the cardiovascular reserve deteriorates below a sustainable limit where the reserve control induces a salvage-sacrifice response, preserving vital organ perfusion while impairing microcirculation effective perfusion in non-vital organ in which it causes cellular hypoxia followed by the familiar devastating cascade of events seen in shock.

DISCUSSION AND CONCLUSIONS

The hereby hypothesis may comprehensively explain the heart failure - shock puzzle as no alternative theory had ever succeeded. It provides the missing link between the different types of HF as of shock and in between. The hypothesis poses a great prove challenge but opens new research and clinical possibilities.

Seven deadly sins in trauma outcomes research: an epidemiologic post mortem for major causes of bias

BACKGROUND

Because randomized clinical trials in trauma outcomes research are expensive and complex, they have rarely been the basis for the clinical care of trauma patients. Most published findings are derived from retrospective and occasionally prospective observational studies that may be particularly susceptible to bias. The sources of bias include some common to other clinical domains, such as heterogeneous patient populations with competing and interdependent short- and long-term outcomes. Other sources of bias are unique to trauma, such as rapidly changing multisystem responses to injury that necessitate highly dynamic treatment regimens such as blood product transfusion. The standard research design and analysis strategies applied in published observational studies are often inadequate to address these biases.

METHODS

Drawing on recent experience in the design, data collection, monitoring, and analysis of the 10-site observational PRospective Observational Multicenter Major Trauma Transfusion (PROMMTT) study, 7 common and sometimes overlapping biases are described through examples and resolution strategies.

RESULTS

Sources of bias in trauma research include ignoring (1) variation in patients' indications for treatment (indication bias), (2) the dependency of intervention delivery on patient survival (survival bias), (3) time-varying treatment, (4) time-dependent confounding, (5) nonuniform intervention effects over time, (6) nonrandom missing data mechanisms, and (7) imperfectly defined variables. This list is not exhaustive.

CONCLUSION

The mitigation strategies to overcome these threats to validity require epidemiologic and statistical vigilance. Minimizing the highlighted types of bias in trauma research will facilitate clinical translation of more accurate and reproducible findings and improve the evidence-base that clinicians apply in their care of injured patients.

Damage control resuscitation from major haemorrhage in polytrauma

Trauma is a global disease that affects patients across the socio-economic spectrum. Uncontrolled major haemorrhage occurs from both blunt and penetrating trauma which may lead to hypovolaemic shock and ultimately death. In polytrauma patients that require urgent resuscitation secondary to major haemorrhage, high volume fluid infusions followed by definitive surgical care have been superseded by damage control resuscitation. DCR is a systematic approach to major trauma that integrates the principles of haemostatic resuscitation, permissive hypotension and damage control surgery (DCS). The aim of DCR is to aggressively minimise hypovolaemic shock and limit the development of coagulopathy, hypothermia and acidosis known as the lethal triad. Besides increased volumes of scientific knowledge to underpin modern trauma resuscitation techniques upon, patient survival is also dependent upon effective teamwork and leadership. In conclusion, successful resuscitation from major haemorrhage depends upon a variety of factors distilled into a trauma team with effective leadership, excellent technical and non-technical team skills as well as the early initiation of DCR.

Review article: Part one: Goal-directed resuscitation--which goals? Haemodynamic targets

The use of appropriate resuscitation targets or end-points may facilitate early detection and appropriate management of shock. There is a fine balance between oxygen delivery and consumption, and when this is perturbed, an oxygen debt is generated. In this narrative review, we explore the value of global haemodynamic resuscitation end-points, including pulse rate, blood pressure, central venous pressure and mixed/central venous oxygen saturations. The evidence supporting the reliability of these parameters as end-points for guiding resuscitation and their potential limitations are evaluated.

Review article: Part two: Goal-directed resuscitation--which goals? Perfusion targets

Haemodynamic targets, such as cardiac output, mean arterial blood pressure and central venous oxygen saturations, remain crude predictors of tissue perfusion and oxygen supply at a cellular level. Shocked patients may appear adequately resuscitated based on normalization of global vital signs, yet they are still experiencing occult hypoperfusion. If targeted resuscitation is employed, appropriate use of end-points is critical. In this review, we consider the value of directing resuscitation at the microcirculation or cellular level. Current technologies available include sublingual capnometry, video microscopy of the microcirculation and near-infrared spectroscopy providing a measure of tissue oxygenation, whereas base deficit and lactate potentially provide a surrogate measure of the adequacy of global perfusion. The methodology and evidence for these technologies guiding resuscitation are considered in this narrative review.