Pathophysiology of fluid imbalance

Beneficial Effect of Pretreatment Hyperosmolality on Outcome in Severe Traumatic Brain Injury: Evidence from a South Korean Multicenter Registry and Propensity Score Matching Analysis

BACKGROUND

Hyperosmolar therapy has long been a cornerstone in managing increased intracranial pressure and improving outcomes in severe traumatic brain injury (TBI). This therapy hinges on elevating serum osmolality, creating an osmotic gradient that draws excess water from the brain's cellular and interstitial compartments and effectively reducing cerebral edema. Given this information, we hypothesized that the serum hyperosmolality prior to any treatment could significantly impact the clinical outcomes of patients with severe TBI, potentially mitigating secondary cerebral edema after trauma.

METHODS

Data were extracted from the Korean Multi-center Traumatic Brain Injury data bank, encompassing 4628 patients with TBI admitted between January 2016 and December 2018. Of these, 507 patients diagnosed with severe TBI (Glasgow Coma Scale score < 9) were selected for comprehensive analysis across four data domains: clinical, laboratory, initial computed tomography scan, and treatment. Serum osmolality was assessed prior to treatment, and the hyperosmolar group was defined by a pretreatment serum osmolality exceeding 320 mOsm/L, whereas favorable outcomes were characterized by a modified Rankin Scale score of ≤ 3 at 6 months after trauma. Multivariate regression with receiver operating characteristic curve analysis and propensity score matching were used to dissect the data set.

RESULTS

Multivariate analysis showed serum osmolality is significantly associated with clinical outcome in patients with severe TBI (p < 0.001). The optimal cutoff value for predicting favorable outcome was 331 mOsm/L, with a sensitivity of 38.9% and a specificity of 87.7%. Notably, the propensity score matching analysis comparing patients with pretreatment serum hyperosmolality with those without indicated a markedly improved functional outcome in the former group (32.5% vs 18.8%, p = 0.025).

CONCLUSIONS

The present study has uncovered a significant correlation between the pretreatment serum osmolality and the clinical outcomes of patients with severe TBI. These findings offer a novel perspective, indicating that a serum hyperosmolality prior to any treatment might potentially have a neuroprotective effect in patients with severe TBI.

Sodium and Its Impact on Outcome After Aneurysmal Subarachnoid Hemorrhage in Patients With and Without Delayed Cerebral Ischemia

OBJECTIVES

To perform a detailed examination of sodium levels, hyponatremia and sodium fluctuations, and their association with delayed cerebral ischemia (DCI) and poor outcome after aneurysmal subarachnoid hemorrhage (aSAH).

DESIGN

An observational cohort study from a prospective SAH Registry.

SETTING

Tertiary referral center focused on SAH treatment in the Amsterdam metropolitan area.

PATIENTS

A total of 964 adult patients with confirmed aSAH were included between 2011 and 2021.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 277 (29%) developed DCI. Hyponatremia occurred significantly more often in DCI patients compared with no-DCI patients (77% vs. 48%). Sodium levels, hyponatremia, hypernatremia, and sodium fluctuations did not predict DCI. However, higher sodium levels were significantly associated with poor outcome in DCI patients (DCI onset -7, DCI +0, +1, +2, +4, +5, +8, +9 d), and in no-DCI patients (postbleed day 6-10 and 12-14). Also, hypernatremia and greater sodium fluctuations were significantly associated with poor outcome in both DCI and no-DCI patients.

CONCLUSIONS

Sodium levels, hyponatremia, and sodium fluctuations were not associated with the occurrence of DCI. However, higher sodium levels, hypernatremia, and greater sodium fluctuations were associated with poor outcome after aSAH irrespective of the presence of DCI. Therefore, sodium levels, even with mild changes in levels, warrant close attention.

Sodium-Glucose Cotransporter 2 Inhibitors Should Be Avoided for the Inpatient Management of Hyperglycemia

OBJECTIVE

Hyperglycemia in patients with type 2 diabetes mellitus is frequently encountered in the hospital setting. The recent guidelines for the management of inpatient hyperglycemia have included the use of dipeptidyl peptidase 4 inhibitors as an alternative to standard insulin therapy in select patients. This raises the question of the inpatient use of sodium-glucose cotransporter 2 inhibitors (SGLT2i), which have gained increasing popularity in the outpatient setting because of beneficial cardiovascular and renal outcomes. This article describes the risks associated with the use of SGLT2i for the management of inpatient hyperglycemia.

METHODS

A literature review was performed using PubMed and Google Scholar for studies assessing the inpatient use of SGLT2i. Search terms included "SGLT2 inhibitors," "euglycemic DKA," "inpatient hyperglycemia," "DPP4 inhibitors," "hypovolemia," and "urinary tract infections." Studies not written in English were excluded. Forty-eight articles were included.

RESULTS

Review of the literature showed significant safety concerns with the use of SGLT2i for the inpatient management of hyperglycemia. Hospitalized patients treated with SGLT2i were at increased risk of diabetic ketoacidosis, euglycemic diabetic ketoacidosis, hypovolemia, and urinary tract infections. When compared head-to-head, SGLT2i were not more effective for inpatient glycemic control than dipeptidyl peptidase 4 inhibitors and did not reduce insulin requirements when used in combination with insulin. Although SGLT2i can be considered for the treatment of congestive heart failure, they should be started close to or at the time of discharge.

CONCLUSION

Although SGLT2i are a preferred pharmacotherapy class for the outpatient management of type 2 diabetes mellitus, there are considerable safety concerns when using them in a hospital setting, and avoidance is recommended.

A Comparison of Normalization Techniques for Individual Baseline-Free Estimation of Absolute Hypovolemic Status Using a Porcine Model

Hypovolemic shock is one of the leading causes of death in the military. The current methods of assessing hypovolemia in field settings rely on a clinician assessment of vital signs, which is an unreliable assessment of hypovolemia severity. These methods often detect hypovolemia when interventional methods are ineffective. Therefore, there is a need to develop real-time sensing methods for the early detection of hypovolemia. Previously, our group developed a random-forest model that successfully estimated absolute blood-volume status (ABVS) from noninvasive wearable sensor data for a porcine model (n = 6). However, this model required normalizing ABVS data using individual baseline data, which may not be present in crisis situations where a wearable sensor might be placed on a patient by the attending clinician. We address this barrier by examining seven individual baseline-free normalization techniques. Using a feature-specific global mean from the ABVS and an external dataset for normalization demonstrated similar performance metrics compared to no normalization (normalization: R2 = 0.82 ± 0.025|0.80 ± 0.032, AUC = 0.86 ± 5.5 × 10-3|0.86 ± 0.013, RMSE = 28.30 ± 0.63%|27.68 ± 0.80%; no normalization: R2 = 0.81 ± 0.045, AUC = 0.86 ± 8.9 × 10-3, RMSE = 28.89 ± 0.84%). This demonstrates that normalization may not be required and develops a foundation for individual baseline-free ABVS prediction.

Effect of controlled hypotensive hemorrhage on plasma sodium levels in anesthetized pigs: An exploratory study

Perioperative hyponatremia, due to non-osmotic release of the antidiuretic hormone arginine vasopressin, is a serious electrolyte disorder observed in connection with many types of surgery. Since blood loss during surgery contributes to the pathogenesis of hyponatremia, we explored the effect of bleeding on plasma sodium using a controlled hypotensive hemorrhage pig model. After 30-min baseline period, hemorrhage was induced by aspiration of blood during 30 min at mean arterial pressure <50 mmHg. Thereafter, the animals were resuscitated with retransfused blood and a near-isotonic balanced crystalloid solution and monitored for 180 min. Electrolyte and water balances, cardiovascular response, renal hemodynamics, and markers of volume regulation and osmoregulation were investigated. All pigs (n = 10) developed hyponatremia. All animals retained hypotonic fluid, and none could excrete net-free water. Urinary excretion of aquaporin 2, a surrogate marker of collecting duct responsiveness to antidiuretic hormone, was significantly reduced at the end of the study, whereas lysine vasopressin, i.e., the pig antidiuretic hormone remained high. In this animal model, hyponatremia developed due to net positive fluid balance and generation of electrolyte-free water by the kidneys. A decreased urinary aquaporin 2 excretion may indicate an escape from antidiuresis.

Reducing incidence of postoperative acute kidney injury in trauma and orthopaedics patients: a quality improvement project

BACKGROUND

Acute kidney injury (AKI) is a common postoperative complication which increases morbidity and mortality. This quality improvement project aimed to implement measures targeting known risk factors to decrease the incidence of postoperative AKI in trauma and orthopaedics (T&O) patients.

METHODS

Data were collected across three six-month to 7-month cycles between 2017 and 2020, analysing all elective and emergency T&O operated patients within a single NHS Trust (n=714, 1008 and 928, respectively). Patients who developed a postoperative AKI were identified using biochemical criteria and data were collected on known AKI risk factors, including use of nephrotoxic medications, and patient outcomes. In the final cycle, the same variables were collected for patients without AKI. Between cycles, measures implemented included: preoperative and postoperative medication reconciliation aiming to stop nephrotoxic medications, orthogeriatrician review of high-risk patients and junior doctor teaching on fluid therapy. Statistical analysis was undertaken to determine the incidence of postoperative AKI across cycles, prevalence of risk factors and impact on length of hospital stay and postoperative mortality.

RESULTS

There was a statistically significant decrease in postoperative AKI incidence from 4.27% (43 of 1008 patients) in cycle 2 to 2.05% (19 of 928) in cycle 3 (p=0.006), with a notable decrease in use of nephrotoxic medications. Significant predictors for the development of postoperative AKI included use of diuretics and receiving multiple nephrotoxic drug classes. Development of postoperative AKI significantly increased length of hospital stay by 7.11 days on average (95% CI: 4.84 to 9.38 days, p<0.001) and risk of 1-year postoperative mortality (OR 3.22, 95% CI: 1.03 to 10.55, p=0.046).

CONCLUSION

This project demonstrates that a multifaceted approach targeting modifiable risk factors can reduce incidence of postoperative AKI in T&O patients, which may lead to reduced length of hospital stay and postoperative mortality.

Controls of Central and Peripheral Blood Pressure and Hemorrhagic/Hypovolemic Shock

The pressure exerted on the heart and blood vessels because of blood flow is considered an essential parameter for cardiovascular function. It determines sufficient blood perfusion, and transportation of nutrition, oxygen, and other essential factors to every organ. Pressure in the primary arteries near the heart and the brain is known as central blood pressure (CBP), while that in the peripheral arteries is known as peripheral blood pressure (PBP). Usually, CBP and PBP are correlated; however, various types of shocks and cardiovascular disorders interfere with their regulation and differently affect the blood flow in vital and accessory organs. Therefore, understanding blood pressure in normal and disease conditions is essential for managing shock-related cardiovascular implications and improving treatment outcomes. In this review, we have described the control systems (neural, hormonal, osmotic, and cellular) of blood pressure and their regulation in hemorrhagic/hypovolemic shock using centhaquine (Lyfaquin^®) as a resuscitative agent.

Reliability of Pre-Induction Inferior Vena Cava Assessment with Ultrasound for the Prediction of Post-Induction Hypotension in Neurosurgical Patients Undergoing Intracranial Surgery

Background

Hypotension is one of the most common complications following induction of general anesthesia. Preemptive diagnosis and correcting the hypovolemic status can reduce the incidence of post-induction hypotension. However, an association between preoperative volume status and severity of post-induction hypotension has not been established in neurosurgical patients. We hypothesized that preoperative ultrasonographic assessment of intravascular volume status can be used to predict post-induction hypotension in neurosurgical patients. Our study objective was to establish the relationship between pre-induction maximum inferior vena cava (IVC) diameter, collapsibility index (CI), and post-induction reduction in mean arterial blood pressure in neurosurgical patients.

Materials and Methods

A prospective observational study was conducted including 100 patients undergoing elective intracranial surgeries. IVC assessment was done before induction of general anesthesia. Receiver operating characteristic (ROC) curve analysis was used to determine the cutoff values of maximum and minimum IVC diameter (IVCD_max and IVCD_min, respectively) and CI for prediction of hypotension.

Results

Post-induction hypotension was observed in 41% patients. Patients with small IVCD_max and higher CI% developed hypotension. The areas under the ROC curve (AUCs) were 0.64 (0.53-0.75) for IVCD_max and 0.69 (0.59-0.80) for IVCD_min. The optimal cutoff values were1.38 cm for IVCD_max and 0.94 cm for IVCD_min. The AUC for CI was 0.65 (0.54-0.77) and the optimal cutoff value was 37.5%.

Conclusion

Pre-induction IVC assessment with ultrasound is a reliable method to predict post-induction hypotension resulting from hypovolemia in neurosurgical patients.

Therapeutic Effect and Prognosis of PiCCO in the Treatment of Myocardial Injury Complicated with Septic Shock

Objective

To explore the effect of pulse-induced contour cardiac output (PiCCO) monitoring on the survival and prognosis of patients with myocardial injury and septic shock.

Methods

A total of 400 patients with MI and septic shock who were treated in our hospital from May 2018 to June 2021 were included in the study. They were randomly grouped into the PiCCO group (n = 200) and the control group (n = 200) according to whether PiCCO was used for monitoring during the treatment period. The clinical baseline characteristics of all the patients were recorded. For comparison, we recorded hemodynamic parameters including mean arterial pressure (MAP), central venous pressure (CVP), heart rate (HR), troponin I (TnI), brain natriuretic peptide (BNP), oxygen metabolism parameters including systemic central venous oxygen saturation (ScvO2), and lactate before and 6 h after intervention. In addition, white blood cell count (WBC) and C-reactive protein (CPR) levels before and 6 h, 24 h, 48 h, and 72 h after intervention were measured in both groups. Finally, the survival and prognostic parameters were compared between the two groups.

Results

At 6 h after monitoring intervention, the hemodynamic parameters of the patients in the PiCCO group were significantly increased. Additionally, compared with the control group, the ScvO2 level was higher while the lactate level was lower in the PiCCO group. An intergroup comparison on inflammation also showed that WBC and CPR levels recovered better in the PiCCO group than in the control group. Moreover, patients with PiCCO monitoring showed better performance in outcome measures such as mortality, duration of invasive mechanical ventilation, length of hospital stay, duration of ventilator use, acute physiology and chronic health scores, and postoperative complications.

Conclusion

With the monitoring and guidance of the PiCCO technique, the nursing outcomes, survival rate, and prognosis of patients with myocardial injury and septic shock can be improved.

Association between fluid overload and mortality in newborns: a systematic review and meta-analysis

Fluid overload (FO) is associated with higher rates of mortality and morbidity in pediatric and adult populations. The aim of this systematic review and meta-analysis was to investigate the association between FO and mortality in critically ill neonates. Systematic search of Ovid MEDLINE, EMBASE, Cochrane Library, trial registries, and gray literature from inception to January 2021. We included all studies that examined neonates admitted to neonatal intensive care units and described FO and outcomes of interest. We identified 17 observational studies with a total of 4772 critically ill neonates who met the inclusion criteria. FO was associated with higher mortality (OR, 4.95 [95% CI, 2.26-10.87]), and survivors had a lower percentage of FO compared with nonsurvivors (WMD, - 4.33 [95% CI, - 8.34 to - 0.32]). Neonates who did not develop acute kidney injury (AKI) had lower FO compared with AKI patients (WMD, - 2.29 [95% CI, - 4.47 to - 0.10]). Neonates who did not require mechanical ventilation on postnatal day 7 had lower fluid balance (WMD, - 1.54 [95% CI, - 2.21 to - 0.88]). FO is associated with higher mortality, AKI, and need for mechanical ventilation in critically ill neonates in the intensive care unit. Strict control of fluid balance to prevent FO is essential. A higher resolution version of the Graphical abstract is available as Supplementary information.

Relationship Between Initial Urine Output and Mortality in Patients Hospitalized in Cardiovascular Intensive Care Units: More Is Not Better

Backgrounds

Decreased urine output (UO) is associated with adverse outcomes in certain patients, but this effect in patients admitted for cardiovascular diseases is still unproven. Moreover, the relationship between increased UO and prognosis is also unclear.

Objective

To investigate the relationship between decreased or increased UO and outcomes in patients with the cardiovascular intensive care unit (CICU).

Methods

This study was a retrospective cohort analysis based on the medical information mart for intensive care III (MIMIC-III) database. The patients' data were extracted from the Beth Israel Deaconess Medical Center (Boston, MA) between 2001 and 2012. With the initial 24-h UO range from 0.5 to 1.0 ml/kg/h as the reference, participants were divided into the several groups. The primary outcome was 30-day mortality. The secondary outcomes were 90-day mortality, ICU mortality, hospital mortality, use of mechanical ventilation (MV), and vasopressor agents in the first 24-h of ICU. The association between UO and mortality was assessed by multivariable logistic regression.

Results

A total of 13,279 patients admitted to CICU were included. Low UO (< 0.5 ml/kg/h) was strongly associated with 30-day mortality (unadjusted OR = 3.993, 95% CI: 3.447–4.625, p < 0.001), and very high UO (≥ 2.0 ml/kg/h) was also a significantly risk factor for 30-day mortality (Unadjusted OR = 2.069, 95% CI: 1.701–2.516, p < 0.001) compared with the reference. The same effects also were shown in the multivariable logistic regression, adjusted by age, gender, vital signs, common comorbidities, and use of diuretics, with an adjusted OR of 2.023 (95% CI: 1.693–2.417, p < 0.001) for low UO and 1.771 (95% CI: 1.389–2.256, p < 0.001) for very high UO. Moreover, both decreased UO and increased UO were risk factors for 90-day mortality, ICU mortality, hospital mortality, use of MV and vasopressor agents.

Conclusion

The decreased and increased UO both were significantly associated with short-term mortality, the relationship between UO and mortality was U-shape rather than linear.

Body temperature, heart rate and long-term outcome of cooled infants: an observational study

BACKGROUND

Therapeutic hypothermia is a standard of care for neonatal encephalopathy; however, approximately one in two newborn infants fails to respond to this treatment. Recent studies have suggested potential relationships between body temperature, heart rate and the outcome of cooled infants.

METHODS

The clinical data of 756 infants registered to the Baby Cooling Registry of Japan between January 2012 and December 2016 were analysed to assess the relationship between body temperature, heart rate and adverse outcomes (death or severe impairment at 18 months corrected age).

RESULTS

A lower body temperature at admission was associated with adverse outcomes in the univariate analysis (P < 0.001), the significance of which was lost when adjusted for the severity of encephalopathy and other covariates. A higher body temperature during cooling and higher heart rate before and during cooling were associated with adverse outcomes in both univariate (all P < 0.001) and multivariate (P = 0.012, P < 0.001 and P < 0.001, respectively) analyses.

CONCLUSIONS

Severe hypoxia-ischaemia might be a common causative of faster heart rates before and during cooling and low body temperature before cooling, whereas causal relationships between slightly higher temperatures during cooling and adverse outcomes need to be elucidated in future studies.

IMPACT

In a large cohort of encephalopathic newborn infants, dual roles of body temperature to the outcome were shown; adverse outcomes were associated with a lower body temperature at admission and higher body temperature during cooling. A higher heart rate before and during cooling were associated with adverse outcomes. Severe hypoxia-ischaemia might be a common causative of faster heart rates before and during cooling and low body temperature before cooling. The exact mechanism underlying the relationship between slightly higher body temperature during cooling and adverse outcomes remains unknown, which needs to be elucidated in future studies.

Heart rate cut-offs to identify non-febrile children with dehydration and acute kidney injury

We hypothesized that the heart rate (HR) variation in an acute setting compared with HR in wellbeing status could be a good marker of both dehydration and acute kidney injury (AKI). Since HR in wellbeing status is unknown in most cases, we assumed as reliable surrogate the 50th percentile of HR according to age and gender. We evaluated if the estimated percentage of heart rate variation in acute setting compared with 50th percentile of HR (EHRV) could be marker of dehydration and AKI in children. Two independent cohorts, one prospective comprehending 185 children at type 1 diabetes mellitus onset (derivation) and one retrospective comprehending 151 children with acute gastroenteritis and pneumonia (validation), were used to develop and externally validate EHRV as predictor of the ≥ 5% dehydration and/or AKI composite outcome. Febrile patients were excluded. EHRV was calculated as ((HR at admission-50th percentile of HR)/HR at admission) × 100. The prevalences of ≥ 5% dehydration and AKI were 61.1% and 43.8% in the derivation and 34.4% and 24.5% in the validation cohort. For the ≥ 5% dehydration and/or AKI composite outcome, the area under receiver-operating characteristic curve of the EHRV in the derivation cohort was 0.69 (95%CI, 0.62-0.77; p < 0.001) and the best EHRV cut-off was > 24.5%. In the validation cohort, EHRV > 24.5% showed specificity = 100% (95%CI, 96.2-100.0), positive predictive value = 100%, and negative predictive value = 67.1% (95%CI, 64.7-69.5). The positive likelihood ratio was infinity, and odds ratio was not calculable because all the patients with EHRV > 24.5% showed ≥ 5% dehydration and/or AKI.    Conclusions: EHRV appears a rather reliable marker of dehydration and AKI. Further validations could allow implementing EHRV in the clinical practice. What is Known: • Increased heart rate (HR) is an easily and quickly detectable sign of dehydration in childhood, but its cut-off to suspect dehydration or acute kidney injury (AKI) is not defined. What is New: • We found that a percentage of estimated HR variation in acute setting in comparison with 50th percentile of HR (EHRV)>24.5% predicted ≥5% dehydration and/or AKI in non-febrile patients. • We provide a one-page tool to suspect ≥5% dehydration and/or AKI on the basis of the HR. If furtherly validated, this tool could be implemented in the daily clinical practice.

Injectable oxygenation therapeutics: evaluating the oxygen delivery efficacy of artificial oxygen carriers and kosmotropes in vitro

The aim of this paper was to utilise an existing in vitro setup to quantify the oxygen offloading capabilities of two different subsets of injectable oxygenation therapeutics: (1) artificial oxygen carriers (AOCs), which bind or dissolve oxygen and act as transport vectors, and (2) kosmotropes, which increase water hydrogen bonding and thereby decrease the resistance to oxygen movement caused by the blood plasma. Dodecafluoropentane emulsion (DDFPe) was chosen to represent the AOC subset while trans sodium crocetinate (TSC) was selected to represent the kosmotrope subset. PEG-Telomer-B (PTB), the surfactant utilised to encapsulate DDFP in emulsion form, was also tested to determine whether it affected the oxygen transport ability of DDFPe. The in vitro set-up was used to simulate a semi closed-loop circulatory system, in which oxygen could be delivered from the lungs to hypoxic tissues. Results of this study showed that (1) 0.5 ml of a PFC outperformed 6.25 ml of a kosmotrope in a controlled, in vitro setting and (2) that PTB and sucrose do not contribute to the overall oxygen transportation efficacy of DDFPe. These results could be therapeutically beneficial to ongoing and future pre-clinical and clinical studies involving various oxygenation agents.

Integrative Physiological Responses to Acute Dehydration in the Rufous-Collared Sparrow: Metabolic, Enzymatic, and Oxidative Traits

Predictions indicate that birds worldwide will be affected by global warming and extreme climatic events which is especially relevant for passerines because the diurnal habits, small body size, and high mass-adjusted metabolic rates of this group make it particularly susceptible to increases in temperature and aridity. Some bird species respond to conditions that stress osmoregulation by increasing their rates of energy expenditure, nevertheless, the effect of dehydration on metabolic rates in birds has produced contrasting results. It also remains unknown whether hydration state may cause shifts in tissue-specific metabolic rates or modify tissue oxidative status. We used the rufous-collared sparrow (Zonotrichia capensis), to experimentally test the effect of dehydration on metabolic enzymes in erythrocytes, tissue oxidative status, basal metabolic rate (BMR), and total evaporative water loss. We found a significant increase in mass-adjusted BMR in water restricted (WR) birds compared to control birds (CT). Activity of cytochrome-c-oxidase (COX) in red blood cells (RBCs) was also significantly higher in the WR group relative to the CT group and this activity was positively correlated with mass-adjusted BMR. We found a moderate effect of water restriction on membrane damage of skeletal muscle. In a second set of individuals subjected to the same experimental conditions, lean mass and total water were tightly correlated and decreased by 10 and 12%, respectively, in birds in the WR group relative to the CT group. Decreases in total water and lean mass leads to an increase in mass-adjusted BMR in WR Z. capensis, suggesting that birds may simultaneously increase protein catabolism and production of metabolic water through oxidation. The significant positive relationship between BMR and COX in RBCs is a finding that requires additional research to determine whether erythrocyte metabolism is affected by dehydration per se and or it more generally reflects rates of energy expenditure in birds.

Haemodynamic frailty - A risk factor for acute kidney injury in the elderly

Clinical frailty in the elderly is defined by a composite measure of functional psychomotor decline. Herein, we develop the concept of haemodynamic frailty (HDF), a state of increased predisposition to disease prevalent in the elderly and characterised by impairment of the network of compensatory responses governing the defence of circulatory volume and adaptive haemodynamic function. We review the factors predisposing the elderly to HDF, with a focus on the impaired capacity to sustain total body water balance. As a component of HDF, dehydration generates vulnerability to diseases caused by tissue hypoperfusion, including acute kidney injury. We provide a detailed mechanistic explanation of how dehydration and depletion of the intravascular volume impacts on renal blood flow to become an important element of the heightened risk of acute kidney injury (AKI) in the elderly. We bring these mechanistic considerations into the clinical context with reference to examples of how pre-renal (haemodynamic) and intrinsic (involving renal parenchymal damage) AKI risk is elevated in the setting of dehydration. Finally, we present HDF as a state of opportunity to prevent disease, for which diagnostic and interventional standards need to be refined. Further prospective studies are warranted to help clarify the clinical utility of assessing and managing HDF with regard to the mitigation of AKI risk in the elderly.

Electrical remodeling and cardiotoxicity precedes structural and functional remodeling of mouse hearts under hyperoxia treatment

Clinical reports suggest a high incidence of ICU mortality with the use of hyperoxia during mechanical ventilation in patients. Our laboratory is pioneer in studying effect of hyperoxia on cardiac pathophysiology. In this study for the first time, we are reporting the sequence of cardiac pathophysiological events in mice under hyperoxic conditions in time-dependent manner. C57BL/6J male mice, aged 8-10 weeks, were treated with either normal air or >90% oxygen for 24, 48, and 72 h. Following normal air or hyperoxia treatment, physical, biochemical, functional, electrical, and molecular parameters were analyzed. Our data showed that significant reduction of body weight observed as early as 24 h hyperoxia treatment, whereas, no significant changes in heart weight until 72 h. Although we do not see any fibrosis in these hearts, but observed significant increase in cardiomyocyte size with hyperoxia treatment in time-dependent manner. Our data also demonstrated that arrhythmias were present in mice at 24 h hyperoxia, and worsened comparatively after 48 and 72 h. Echocardiogram data confirmed cardiac dysfunction in time-dependent manner. Dysregulation of ion channels such as Kv4.2 and KChIP2; and serum cardiac markers confirmed that hyperoxia-induced effects worsen with each time point. From these observations, it is evident that electrical remodeling precedes structural remodeling, both of which gets worse with length of hyperoxia exposure, therefore shorter periods of hyperoxia exposure is always beneficial for better outcome in ICU/critical care units.

Zero-Balance Ultrafiltration during Cardiopulmonary Bypass Is Associated with Decreased Urine Output

Zero-balance ultrafiltration (ZBUF) during cardiopulmonary bypass (CPB) has been purported to reduce pro-inflammatory mediators during cardiac surgery. However, its clinical benefit is equivocal and its effect on renal function unknown. The purpose of this study was to examine the effect of ZBUF on urine output in adult patients undergoing CPB. Following institutional review board approval, 98,953 records from a national registry of adult patients at 215 U.S. hospitals between January 2016 and September 2019 were reviewed. Groups were stratified according to ZBUF use. Anuric patients were excluded from the study as they were patients with missing data on urine output, ultrafiltration use, or ZBUF volume. The primary endpoint was intraoperative urine output normalized to body weight and procedure duration (total operative time). Final analysis of this endpoint was carried out using a linear mixed-effects regression model adjusting for patient and procedural characteristics, as well as practice patterns associated with surgeons and perfusionists. There was a significant 16.1% reduction in median urine output for ZBUF patients (.94 [.54, 1.47] mL/kg/h) vs. the non-ZBUF group (1.12 [.70,-1.73] mL/kg/h), p < .001. After statistically adjusting for patient and procedural characteristics, each liter of ZBUF volume was associated with an estimated change in intraoperative urine output of -.03 mL/kg/h (95% CI: [-.04 to -.02], p < .001). The median ZBUF volume was 1,550 [1,000, 2,600] mL, and when ZBUF was used, conventional ultrafiltration (CUF) was more likely to be used as well (88.4% vs. 44.8%, p < .001). ZBUF patients had median asanguineous volume and crystalloid cardioplegia nearly two times more than non-ZBUF patients, and had slightly higher red blood cell transfusions (17.6% vs. 16.3%, p < .05). The application of ZBUF during CPB was associated with patients having lower urine output and significantly higher use of CUF. Further research is required to determine if these results are reproducible in prospective clinical studies.

Profiling Mannheimia haemolytica infection in dairy calves using near infrared spectroscopy (NIRS) and multivariate analysis (MVA)

Bovine respiratory disease (BRD) linked with Mannheimia haemolytica is the principal cause of pneumonia in cattle. Diagnosis of BRD traditionally relies on visual assessment, which can be untimely, insensitive, and nonspecific leading to inadequate treatment and further spread of disease. Near Infrared Spectroscopy (NIRS) is a rapid acquisition vibrational spectroscopy that can profile changes in biofluids, and when used in combination with multivariate analysis, has potential for disease diagnosis. This study characterizes the NIR spectral profile of blood plasma from dairy calves infected with M. haemolytica and validates the spectral biochemistry using standardized clinical and hematological reference parameters. Blood samples were collected for four days prior to (baseline), and 23 days after, a controlled intrabronchial challenge. NIR spectral profiles of blood plasma discriminated and predicted Baseline and Infected states of animal disease progression with accuracy, sensitivity, and specificity ≥ 90% using PCA–LDA models. These results show that physiological and biochemical changes occurring in the bloodstream of dairy calves during M. haemolytica infection are reflected in the NIR spectral profiles, demonstrating the potential of NIRS as a diagnostic and monitoring tool of BRD over time.

Blood Pressure Management in Acute Ischemic Stroke

PURPOSE OF REVIEW

Abrupt blood pressure (BP) rise is the most common clinical symptom of acute ischemic stroke (AIS). However, BP alterations during AIS reflect many diverse mechanisms, both stroke-related and nonspecific epiphenomena, which change over time and across patients. While extremes of BP as well as high BP variability have been related with worse outcomes in observational studies, optimal BP management after AIS remains challenging.

RECENT FINDINGS

This review discusses the complexity of the factors linking BP changes to the clinical outcomes of patients with AIS, depending on the treatment strategy and local vessel status and, in particular, the degree of reperfusion achieved. The evidence for possible additional clinical markers, including the presence of arterial hypertension, and comorbid organ dysfunction in individuals with AIS, as informative and helpful factors in therapeutic decision-making concerning BP will be reviewed, as well as recent data on neurovascular monitoring targeting person-specific local cerebral perfusion and metabolic demand, instead of the global traditional parameters (BP among others) alone. The individualization of BP management protocols based on a complex evaluation of the homeostatic response to focal cerebral ischemia, including but not limited to BP changes, may be a valuable novel goal proposed in AIS, but further trials are warranted.

The Effect of Fluid Overload on Attributable Morbidity after Cardiac Surgery: A Retrospective Study

INTRODUCTION

Although the detrimental effects of excessive perioperative fluid administration are generally well established, data in the setting of cardiac surgery remain less robust.

METHODS

In this retrospective single-center observational study, the total fluid balance in the first 12 hours during and after surgery was evaluated. Primary endpoint was the relationship between total fluid balance and the incidence of prolonged mechanical ventilation. For this purpose, data were divided into quartiles (Q); prolonged mechanical ventilation and prolonged length of stay (LOS) in the ICU were defined as Q4. Secondary endpoints were prolonged LOS in the ICU, incidence of acute kidney injury (AKI; defined as a 1.5-fold increase in serum creatinine during, relative to baseline), and ICU mortality.

RESULTS

In a 3-year period, 748 patients were included. In a univariate analysis, the median duration of mechanical ventilation was 2.9 h [2.4-3.7] in Q1 of the fluid balance and increased significantly to 4.7 h [3.1-9.2] in Q4 of the fluid balance (p < 0.001). In addition, patients in Q4 of the fluid balance had a significantly longer LOS in the ICU, as well as a higher incidence of AKI and ICU mortality. In a multivariate analysis, Q4 of the fluid balance was independently associated with prolonged mechanical ventilation (OR 4.9, CI 2.9-8.4, p < 0.001) and prolonged LOS in the ICU (OR 11.3 CI 6.1-20,9, p < 0.001), but not with the incidence of AKI or ICU mortality.

CONCLUSIONS

Perioperative fluid administration in cardiac surgery patients was independently associated with prolonged mechanical ventilation and prolonged LOS in the ICU.

Role of intraoperative oliguria in risk stratification for postoperative acute kidney injury in patients undergoing colorectal surgery with an enhanced recovery protocol: A propensity score matching analysis

BACKGROUND

The enhanced recovery after surgery (ERAS) protocol for colorectal cancer resection recommends balanced perioperative fluid therapy. According to recent guidelines, zero-balance fluid therapy is recommended in low-risk patients, and immediate correction of low urine output during surgery is discouraged. However, several reports have indicated an association of intraoperative oliguria with postoperative acute kidney injury (AKI). We investigated the impact of intraoperative oliguria in the colorectal ERAS setting on the incidence of postoperative AKI.

PATIENTS AND METHODS

From January 2017 to August 2019, a total of 453 patients underwent laparoscopic colorectal cancer resection with the ERAS protocol. Among them, 125 patients met the criteria for oliguria and were propensity score (PS) matched to 328 patients without intraoperative oliguria. After PS matching had been performed, 125 patients from each group were selected and the incidences of AKI were compared between the two groups. Postoperative kidney function and surgical outcomes were also evaluated.

RESULTS

The incidence of AKI was significantly higher in the intraoperative oliguria group than in the non-intraoperative oliguria group (26.4% vs. 11.2%, respectively, P = 0.002). Also, the eGFR reduction on postoperative day 0 was significantly greater in the intraoperative oliguria than non-intraoperative oliguria group (-9.02 vs. -1.24 mL/min/1.73 m2 respectively, P < 0.001). In addition, the surgical complication rate was higher in the intraoperative oliguria group than in the non-intraoperative oliguria group (18.4% vs. 9.6%, respectively, P = 0.045).

CONCLUSIONS

Despite the proven benefits of perioperative care with the ERAS protocol, caution is required in patients with intraoperative oliguria to prevent postoperative AKI. Further studies regarding appropriate management of intraoperative oliguria in association with long-term prognosis are needed in the colorectal ERAS setting.

Cellular Stress and General Pathological Processes

From the viewpoint of the general pathology, most of the human diseases are associated with a limited number of pathogenic processes such as inflammation, tumor growth, thrombosis, necrosis, fibrosis, atrophy, pathological hypertrophy, dysplasia and metaplasia. The phenomenon of chronic low-grade inflammation could be attributed to non-classical forms of inflammation, which include many neurodegenerative processes, pathological variants of insulin resistance, atherosclerosis, and other manifestations of the endothelial dysfunction. Individual and universal manifestations of cellular stress could be considered as a basic element of all these pathologies, which has both physiological and pathophysiological significance. The review examines the causes, main phenomena, developmental directions and outcomes of cellular stress using a phylogenetically conservative set of genes and their activation pathways, as well as tissue stress and its role in inflammatory and para-inflammatory processes. The main ways towards the realization of cellular stress and its functional blocks were outlined. The main stages of tissue stress and the classification of its typical manifestations, as well as its participation in the development of the classical and non-classical variants of the inflammatory process, were also described. The mechanisms of cellular and tissue stress are structured into the complex systems, which include networks that enable the exchange of information with multidirectional signaling pathways which together make these systems internally contradictory, and the result of their effects is often unpredictable. However, the possible solutions require new theoretical and methodological approaches, one of which includes the transition to integral criteria, which plausibly reflect the holistic image of these processes.

Preventing acute kidney injury in high-risk patients by temporarily discontinuing medication - an observational study in general practice

BACKGROUND

Elderly, patients with chronic kidney disease (CKD) and patients with heart failure who continue using renin-angiotensin-aldosterone-system (RAAS) inhibitors, diuretics, or non-steroidal-anti-inflammatory drugs (NSAIDs) during times of fluid loss have a high risk of developing complications like acute kidney injury (AKI). The aim of this study was to assess how often advice to discontinue high-risk medication was offered to high-risk patients consulting the general practitioner (GP) with increased fluid loss. Furthermore, we assessed the number and nature of the complications that occurred after GP consultation.

METHODS

We performed a cross-sectional study with patients from seven Dutch general practices participating in the Family Medicine Network between 1 and 6-2013 and 1-7-2018. We included patients who used RAAS-inhibitors, diuretics, or NSAIDs, and had at least one of the following risk factors: age ≥ 70 years, CKD, or heart failure. From this population, we selected patients with a 'dehydration-risk' episode (vomiting, diarrhoea, fever, chills, or gastrointestinal infection). We manually checked their electronic patient files and assessed the percentage of episodes in which advice to discontinue the high-risk medication was offered and whether a complication occurred in 3 months after the 'dehydration-risk' episode.

RESULTS

We included 3607 high-risk patients from a total of 44.675 patients (8.1%). We found that patients were advised to discontinue the high-risk medication in 38 (4.6%) of 816 'dehydration-risk' episodes. In 59 of 816 episodes (7.1%) complications (mainly AKI) occurred.

CONCLUSIONS

Dutch GPs do not frequently advise high-risk patients to discontinue high-risk medication during 'dehydration-risk' episodes. Complications occur frequently. Timely discontinuation of high-risk medication needs attention.

Timing of major fracture care in polytrauma patients - An update on principles, parameters and strategies for 2020

OBJECTIVES

Sustained changes in resuscitation and transfusion management have been observed since the turn of the millennium, along with an ongoing discussion of surgical management strategies. The aims of this study are threefold: a) to evaluate the objective changes in resuscitation and mass transfusion protocols undertaken in major level I trauma centers; b) to summarize the improvements in diagnostic options for early risk profiling in multiply injured patients and c) to assess the improvements in surgical treatment for acute major fractures in the multiply injured patient.

METHODS

I. A systematic review of the literature (comprehensive search of the MEDLINE, Embase, PubMed, and Cochrane Central Register of Controlled Trials databases) and a concomitant data base (from a single Level I center) analysis were performed. Two authors independently extracted data using a pre-designed form. A pooled analysis was performed to determine the changes in the management of polytraumatized patients after the change of the millennium. II. A data base from a level I trauma center was utilized to test any effects of treatment changes on outcome.

INCLUSION CRITERIA

adult patients, ISS > 16, admission < less than 24 h post trauma. Exclusion: Oncological diseases, genetic disorders that affect the musculoskeletal system. Parameters evaluated were mortality, ICU stay, ICU complications (Sepsis, Pneumonia, Multiple organ failure).

RESULTS

I. From the electronic databases, 5141 articles were deemed to be relevant. 169 articles met the inclusion criteria and a manual review of reference lists of key articles identified an additional 22 articles. II. Out of 3668 patients, 2694 (73.4%) were male, the mean ISS was 28.2 (SD 15.1), mean NISS was 37.2 points (SD 17.4 points) and the average length of stay was 17.0 days (SD 18.7 days) with a mean length of ICU stay of 8.2 days (SD 10.5 days), and a mean ventilation time of 5.1 days (SD 8.1 days). Both surgical management and nonsurgical strategies have changed over time. Damage control resuscitation, dynamic analyses of coagulopathy and lactate clearance proved to sharpen the view of the worsening trauma patient and facilitated the prevention of further complications. The subsequent surgical care has become safer and more balanced, avoiding overzealous initial surgeries, while performing early fixation, when patients are physiologically stable or rapidly improving. Severe chest trauma and soft tissue injuries require further evaluation.

CONCLUSIONS

Multiple changes in management (resuscitation, transfusion protocols and balanced surgical care) have taken place. Moreover, improvement in mortality rates and complications associated with several factors were also observed. These findings support the view that the management of polytrauma patients has been substantially improved over the past 3 decades.

Body fluid volume homeostasis is abnormal in pregnancies complicated with hypertension and/or poor fetal growth

OBJECTIVES

To evaluate body water volumes and cardiac output in each trimester of pregnancies complicated with hypertension and/or poor fetal growth, relative to uncomplicated pregnancy.

METHODS

In this semi-longitudinal cohort study, a standardised non-invasive maternal hemodynamics assessment in first, second or third trimester was performed in 1068 women with uncomplicated pregnancy (UP), 75 with early onset (EPE) and 117 with late onset preeclampsia (LPE), 139 with gestational hypertension (GH), 129 with small for gestational age (SGA) neonates and 43 with essential hypertension (EH). Women with hypertension or SGA were included prior to onset of symptoms or at diagnosis of disease; 46% of women (758/1631) were assessed in ≥ 2 trimesters. Impedance cardiography and spectrum analysis were used to measure cardiac output, total body water (TBW), extracellular (ECW) and intracellular water (ICW). A linear mixed model was used for inter-trimestrial comparison of parity-, age- and BMI-corrected values within and between groups.

RESULTS

For all pregnancies, TBW is higher in each consecutive trimester, mainly due to increasing fraction of ECW (ECW%). Compared to first trimester UP, ECW and ECW% are higher in EPE whereas TBW, ECW and ICW are lower in SGA. Compared to inter-trimestrial differences in UP, abnormal changes for body water volumes are observed in GH, EPE and LPE and for CO in EPE and LPE. Changes in EH are not different from UP.

CONCLUSIONS

This study is the first to show that concomitant gestational changes of ECW and CO are different from UP already in preclinical stages of pregnancies complicated with hypertension and/or poor fetal growth, except EH. This finding highlights the relevance of early gestational assessment of maternal body fluid status in pregnancies at risk for hypertension or poor fetal growth.

6% Hydroxyethyl starch (HES 130/0.4) diminishes glycocalyx degradation and decreases vascular permeability during systemic and pulmonary inflammation in mice

Background

Increased vascular permeability is a pathophysiological hallmark of sepsis and results in increased transcapillary leakage of plasma fluid, hypovolemia, and interstitial edema formation. 6% hydroxyethyl starch (HES 130/0.4) is commonly used to treat hypovolemia to maintain adequate organ perfusion and oxygen delivery. The present study was designed to investigate the effects of 6% HES 130/0.4 on glycocalyx integrity and vascular permeability in lipopolysaccharide (LPS)-induced pulmonary inflammation and systemic inflammation in mice.

Methods

6% HES 130/0.4 or a balanced electrolyte solution (20 ml/kg) was administered intravenously 1 h after cecal ligation and puncture (CLP) or LPS inhalation. Sham-treated animals receiving 6% HES 130/0.4 or the electrolyte solution served as controls. The thickness of the endovascular glycocalyx was visualized by intravital microscopy in lung (LPS inhalation model) or cremaster muscle (CLP model). Syndecan-1, hyaluronic acid, and heparanase levels were measured in blood samples. Vascular permeability in the lungs, liver, kidney, and brain was measured by Evans blue extravasation.

Results

Both CLP induction and LPS inhalation resulted in increased vascular permeability in the lung, liver, kidney, and brain. 6% HES 130/0.4 infusion led to significantly reduced plasma levels of syndecan-1, heparanase, and hyaluronic acid, which was accompanied by a preservation of the glycocalyx thickness in postcapillary venules of the cremaster (0.78 ± 0.09 μm vs. 1.39 ± 0.10 μm) and lung capillaries (0.81 ± 0.09 μm vs. 1.49 ± 0.12 μm).

Conclusions

These data suggest that 6% HES 130/0.4 exerts protective effects on glycocalyx integrity and attenuates the increase of vascular permeability during systemic inflammation.

Electronic supplementary material

The online version of this article (doi: 10.1186/s13054-017-1846-3) contains supplementary material, which is available to authorized users.

Recognition and management of idiopathic systemic capillary leak syndrome: an evidence-based review

INTRODUCTION

Idiopathic systemic capillary leak syndrome (SCLS) is a unique disorder characterized by episodes of massive systemic leak of intravascular fluid leading to volume depletion and shock. A typical attack of SCLS consists of prodromal, leak and post-leak phases. Complications, such as compartment syndrome and pulmonary edema, usually develop during the leak and post-leak phases respectively. Judicious intravenous hydration and early use of vasopressors is the cornerstone of management in such cases. Areas covered: The purpose of the present review is to provide an up-to-date, evidence-based review of our understanding of SCLS and its management in the light of currently available evidence.

COMMENTARY

Idiopathic SCLS was first described in 1960 and, since then, more than 250 cases have been reported. A large number of cases have been reported over the past one decade, most likely due to improved recognition. In the acute care setting, most patients with SCLS are managed as per the Surviving Sepsis guidelines and receive aggressive volume resuscitation - which is not the optimal management strategy for such patients. There is a need to raise awareness amongst physicians and clinicians in order to improve recognition of this disorder and ensure its appropriate management.

Toward a Reasoned Classification of Diseases Using Physico-Chemical Based Phenotypes

Background: Diseases and health conditions have been classified according to anatomical site, etiological, and clinical criteria. Physico-chemical mechanisms underlying the biology of diseases, such as the flow of energy through cells and tissues, have been often overlooked in classification systems.

Objective: We propose a conceptual framework toward the development of an energy-oriented classification of diseases, based on the principles of physical chemistry.

Methods: A review of literature on the physical chemistry of biological interactions in a number of diseases is traced from the point of view of the fluid and solid mechanics, electricity, and chemistry.

Results: We found consistent evidence in literature of decreased and/or increased physical and chemical forces intertwined with biological processes of numerous diseases, which allowed the identification of mechanical, electric and chemical phenotypes of diseases.

Discussion: Biological mechanisms of diseases need to be evaluated and integrated into more comprehensive theories that should account with principles of physics and chemistry. A hypothetical model is proposed relating the natural history of diseases to mechanical stress, electric field, and chemical equilibria (ATP) changes. The present perspective toward an innovative disease classification may improve drug-repurposing strategies in the future.

Novel Insights into the Pathogenesis and Prevention of Intradialytic Hypotension

BACKGROUND

Intradialytic hypotension (IDH) is a common complication of haemodialysis (HD) and associated with adverse outcomes, especially when a nadir definition (systolic blood pressure <90 mm Hg) is used. The pathogenesis of IDH is directly linked to the discontinuous nature of the HD treatment, in combination with patient-related factors such as age, diabetes mellitus and cardiac failure.

SUMMARY

Although the decline in blood volume due to removal of fluid by ultrafiltration is the prime mover, thermally induced reflex vasodilation compromises the haemodynamic response to hypovolemia. Recent studies have stressed the relevance of changes in tissue perfusion during HD, which may translate in long-term organ damage. Monitoring changes in tissue perfusion, for which emerging evidence becomes available, appears to have great promise in the fine-tuning of the dialysis procedure. Key Messages: While it is unlikely that IDH can be completely prevented, reduction in inter-dialytic weight gain, prevention of an increase in core temperature by adjusting the dialysate temperature and more frequent or prolonged dialysis treatment remain cornerstones in providing a more comfortable and safe treatment.

Proposal for heart failure progression based on the 'chloride theory': worsening heart failure with increased vs. non-increased serum chloride concentration

AIMS

Chloride (Cl) is an established key electrolyte for the activation of the renin-angiotensin-aldosterone system. Recent studies have shown the serum Cl as a key electrolyte for the regulation of body fluid distribution in heart failure (HF) patients. The clinical differences of worsening HF status according to the changes in serum Cl concentration are unclear.

METHODS AND RESULTS

Data from 47 chronic HF patients were analysed. Upon worsening HF, each patient exhibited at least two HF-related signs. Blood tests included haemoglobin (Hb), haematocrit (Ht), mean red blood cell volume (MCV), albumin, serum solutes, and b-type natriuretic peptide. The relative change in the plasma volume (%PV) from stable to worsening HF was estimated as follows: 100 × {Hb (stable) × [1 - Ht (worse)]}/{Hb (worse) × [1 - Ht (stable)]} - 100. When patients were divided into two groups based on changes in serum Cl concentration from stable to worsening HF, the pathophysiologic features of the patients with increased Cl (range 1-23 mEq/L; n = 31) included a greater increase in serum sodium (2.94 ± 4.15 vs. -0.69 ± 3.75 mEq/L, P = 0.005), higher vascular expansion (12 ± 11.1 vs. 4.81 ± 7.94%, P = 0.026), a tendency towards a greater MCV (1.23 ± 2.36 vs. -0.06 ± 1.88 fL, P = 0.065), and preserved renal function defined by the absence of an increase of serum creatinine (-0.24 ± 0.39 vs. -0.05 ± 0.12 mg/dL, P = 0.057) compared to patients with non-increased Cl (range -9 to 0 mEq/L; n = 16). Clinically, the increased Cl group had fewer HF signs (2.65 ± 0.71 vs. 3.31 ± 0.79, P = 0.005) although the change in symptoms did not differ between groups (48% vs. 63%, P = 0.54).

CONCLUSIONS

The present study suggests a new clinical entity of worsening HF status, that is, HF with increased vs. non-increased serum Cl concentration from clinical stability to worsening HF.

ELABELA Improves Cardio-Renal Outcome in Fatal Experimental Septic Shock

OBJECTIVES

Apelin-13 was recently proposed as an alternative to the recommended β-adrenergic drugs for supporting endotoxin-induced myocardial dysfunction. Since Apelin-13 signals through its receptor (Apelin peptide jejunum) to exert singular inotropic/vasotropic actions and to optimize body fluid balance, this candidate pathway might benefit septic shock management. Whether the newly discovered ELABELA (ELA), a second endogenous ligand of the Apelin peptide jejunum receptor highly expressed in the kidney, further improves cardio-renal impairment remains unknown.

DESIGN, SETTING, AND SUBJECTS

Interventional study in a rat model of septic shock (128 adult males) to assess the effects of ELA and Apelin-13 on vascular and cardio-renal function. Experiments were performed in a tertiary care University-based research institute.

INTERVENTIONS

Polymicrobial sepsis-induced cardiac dysfunction was produced by cecal ligation puncture to assess hemodynamic efficacy, cardioprotection, and biomechanics under acute or continuous infusions of the apelinergic agonists ELA or Apelin-13 (39 and 15 µg/kg/hr, respectively) versus normal saline.

MEASUREMENTS AND MAIN RESULTS

Apelinergic agonists improved 72-hour survival after sepsis induction, with ELA providing the best clinical outcome after 24 hours. Apelinergic agonist infusion counteracted cecal ligation puncture-induced myocardial dysfunction by improving left ventricular pressure-volume relationship. ELA-treated cecal ligation puncture rats were the only group to 1) display a significant improvement in left ventricular filling as shown by increased E-wave velocity and left ventricular end-diastolic volume, 2) exhibit a higher plasma volume, and 3) limit kidney injury and free-water clearance. These beneficial renal effects were superior to Apelin-13, likely because full-length ELA enabled a distinctive regulation of pituitary vasopressin release.

CONCLUSIONS

Activation of the apelinergic system by exogenous ELA or Apelin-13 infusion improves cardiovascular function and survival after cecal ligation puncture-induced sepsis. However, ELA proved better than Apelin-13 by improving fluid homeostasis, cardiovascular hemodynamics recovery, and limiting kidney dysfunction in a vasopressinergic-dependent manner.

New WHO recommendations on intraoperative and postoperative measures for surgical site infection prevention: an evidence-based global perspective

Surgical site infections (SSIs) are the most common health-care-associated infections in developing countries, but they also represent a substantial epidemiological burden in high-income countries. The prevention of these infections is complex and requires the integration of a range of preventive measures before, during, and after surgery. No international guidelines are available and inconsistencies in the interpretation of evidence and recommendations in national guidelines have been identified. Considering the prevention of SSIs as a priority for patient safety, WHO has developed evidence-based and expert consensus-based recommendations on the basis of an extensive list of preventive measures. We present in this Review 16 recommendations specific to the intraoperative and postoperative periods. The WHO recommendations were developed with a global perspective and they take into account the balance between benefits and harms, the evidence quality level, cost and resource use implications, and patient values and preferences.

Hyperaldosteronism and its association with hypotension and azotaemia in canine babesiosis

BACKGROUND

The previous work on canine babesiosis revealed hypokalaemia and increased fractional excretion of potassium in infected dogs suggesting a role for aldosterone in the loss of potassium via the kidneys in affected dogs. Moreover, hypotension, which is one of the complications of canine babesiosis leading to renal failure, may induce secondary hyperaldosteronism.

ANIMALS AND METHODS

In this study, the serum aldosterone concentration was determined in 14 dogs infected with Babesia canis. The Mann-Whitney U test was used to compare serum aldosterone concentration and blood pressure between these dogs and 10 healthy dogs. Spearman's rank correlations between serum aldosterone concentration and blood pressure and between serum aldosterone and urea and creatinine concentrations were calculated.

RESULTS

Increased concentrations of aldosterone above reference intervals were observed in only 4 out of the 14 dogs. The results showed significantly (p < 0.05) higher serum aldosterone concentrations and lower blood pressures in infected dogs in comparison to healthy dogs, and significantly negative correlations between aldosterone concentration and systolic arterial pressure (r = -0.63), diastolic arterial pressure (r = -0.67) and mean arterial pressure (r = -0.65). Serum aldosterone concentration was also significantly correlated with serum urea concentration (r = 0.72), serum creatinine concentration (r = 0.69) and serum potassium concentration (r = -0.57).

CONCLUSION

The results of this study show hyperaldosteronism in some cases of canine babesiosis as a possible response to hypotension. However, both the hypotension and severe azotaemia observed in dogs infected with B. canis and associated hyperaldosteronaemia suggest that this response is insufficient.

Effects of weekly blood collection in male and female cynomolgus macaques (Macaca fascicularis)

This study was designed to evaluate the maximal amount of blood that can be safely collected in healthy, adult male and female cynomolgus macaques for 4 consecutive weeks with minimal effect on animal wellbeing. General guidelines for blood collection volumes in laboratory animals are not species-specific, and currently there are few evaluations of blood collection in macaques. In this study, blood was removed at 7.5%, 10%, 12.5%, 15%, or 17.5% of total blood volume (TBV) for 4 consecutive weeks. Hematologic parameters and body weights were evaluated immediately prior to each blood collection time point and for an additional 4 consecutive weeks following the last collection. Male and female macaques tolerated removal of as much as 15% TBV with minor clinical effects, whereas macaques in the 17.5% TBV group exhibited an increased incidence of emesis and anorexia during the first 24 h after blood collection. According to these results, we recommend collecting no more than 15% TBV weekly for 4 consecutive weeks from healthy, adult male and female cynomolgus macaques.

Effect of experimentally induced hypovolemia on ertapenem tissue distribution using microdialysis in rats

Hypovolemia is a common event in critical care patients that may affect drug distribution and elimination. In order to better understand this issue the effect of hypovolemia on the plasma protein binding and tissue distribution of ertapenem was investigated in rats using microdialysis. Microdialysis probes were inserted into the jugular vein and hind leg muscle. Ertapenem recoveries in muscle and blood were determined in each rat by retrodialysis by drug before drug administration. Hypovolemia was induced in 6 rats by removing 40% of the initial blood volume over 30 min. Ertapenem was infused intravenously at a dose of 40 mg kg(-1) over 30 min, and microdialysis samples were collected for 310 min. The unbound concentration profiles in muscle and blood were virtually superimposed in both groups except at early time points. The ratios of the area under the concentration-time curve (AUC) for tissue to the AUC for blood were 0.7±0.2 and 0.8±0.2 for control and hypovolemic rats, respectively. Hypovolemia induced a 40% decrease in the clearance of ertapenem, with no statistically significant alteration of its volume of distribution. This study showed that ertapenem elimination was altered in hypovolemic rats, probably due to decreased renal blood flow, but its distribution characteristics were not. Unbound concentrations of ertapenem in blood and muscle were always virtually identical.

Capillary leak syndrome in trauma: what is it and what are the consequences?

TICS is a complex disease that is clearly multifactorial in the traumatically injured patient (Fig. 2). Although systemic inflammation that occurs directly as a result of injury plays the most prominent role, the local tissue and organ injury effects of trauma not only cause local capillary leak and edema but also further amplify the SIRS response. High volume fluid administration and hypoproteinemic states further exacerbate the problem. All of this leads to organ dysfunction and failure, which is the third leading cause of death following injury. Strategies to treat TICS and attenuate its effects once it occurs by targeting inflammatory pathways have been wholly unsuccessful. The mainstay of therapy for TICS is prevention and minimization of its lethal effects. Newer resuscitation strategies such as hemostatic resuscitation and early goal-directed therapies are currently the best available strategies to combat TICS. Whether these result in better outcomes remains to be seen and the authors anxiously await the results of well-designed prospective trials.

Use of BNP and bioimpedance to drive therapy in heart failure patients

The aim of the study was to verify whether the bioimpedance vector analysis (BIVA) could be a valid methodology to assess the fluid overload, whether there was a correlation between brain natriuretic peptide (BNP) and the fluid overload detected by BIVA, and whether this technique could be a valid guide in the management of the therapy in patients with acute decompensated heart failure (ADHF). A total of 51 patients arriving to the emergency department of the University Hospital Sant'Andrea (Rome, Italy) from December 2008 to April 2009 were enrolled. Hydration state, BNP, and caval index were evaluated at admission in the emergency department, at 24 and 72 hours, and at discharge. Vascular pedicle width was evaluated at admission and at discharge. BIVA values were correlated with BNP levels. A follow-up by phone at 3 months was performed. ADHF patients showed higher values of hydration state compared with controls. In ADHF patients, the difference between t 0 and t 72 BIVA mean values (P<.001) and between t 0 and discharge BIVA mean value (P<.0001) was statistically significant. Vascular pedicle width in ADHF patients showed a statistically significant difference (P<.0004) in compared with vascular pedicle width in controls.

Critical illness, gastrointestinal complications, and medication therapy during enteral feeding in critically ill adult patients

Critically ill patients who are subjected to high stress or with severe injury can rapidly break down their body protein and energy stores. Unless adequate nutrition is provided, malnutrition and protein wasting may occur, which can negatively affect patient outcome. Enteral nutrition (EN) is the mainstay of nutrition support therapy in patients with a functional gastrointestinal (GI) tract who cannot take adequate oral nutrition. EN in critically ill patients provides the benefits of maintaining gut functionality, integrity, and immunity as well as decreasing infectious complications. However, the ability to provide timely and adequate EN to critically ill patients is often hindered by GI motility disorders and complications associated with EN. This paper reviews the GI complications and intolerances associated with EN in critically ill patients and provides recommendations for their prevention and treatment. It also addresses the role of commonly used medications in the intensive care unit and their impact on GI motility and EN delivery.

Vasodilation increases pulse pressure variation, mimicking hypovolemic status in rabbits

OBJECTIVE

To test the hypothesis that pulse pressure respiratory variation (PPV) amplification, observed in hypovolemia, can also be observed during sodium nitroprusside (SNP)-induced vasodilation.

INTRODUCTION

PPV is largely used for early identification of cardiac responsiveness, especially when hypovolemia is suspected. PPV results from respiratory variation in transpulmonary blood flow and reflects the left ventricular preload variations during respiratory cycles. Any factor that decreases left ventricular preload can be associated with PPV amplification, as seen in hypovolemia.

METHODS

Ten anesthetized and mechanically ventilated rabbits underwent progressive hypotension by either controlled hemorrhage (Group 1) or intravenous SNP infusion (Group 2). Animals in Group 1 (n = 5) had graded hemorrhage induced at 10% steps until 50% of the total volume was bled. Mean arterial pressure (MAP) steps were registered and assumed as pressure targets to be reached in Group 2. Group 2 (n = 5) was subjected to a progressive SNP infusion to reach similar pressure targets as those defined in Group 1. Heart rate (HR), systolic pressure variation (SPV) and PPV were measured at each MAP step, and the values were compared between the groups.

RESULTS

SPV and PPV were similar between the experimental models in all steps (p > 0.16). SPV increased earlier in Group 2.

CONCLUSION

Both pharmacologic vasodilation and graded hemorrhage induced PPV amplification similar to that observed in hypovolemia, reinforcing the idea that amplified arterial pressure variation does not necessarily represent hypovolemic status but rather potential cardiovascular responsiveness to fluid infusion.

Perioperative hemodynamic monitoring with transesophageal Doppler technology

Invasive cardiac output (CO) monitoring, traditionally performed with transpulmonary thermodilution techniques, is usually reserved for high-risk patients because of the inherent risks of these methods. In contrast, transesophageal Doppler (TED) technology offers a safe, quick, and less invasive method for routine measurements of CO. After esophageal insertion and focusing of the probe, the Doppler beam interrogates the descending aortic blood flow. On the basis of the measured frequency shift between the emitted and received ultrasound frequency, blood flow velocity is determined. From this velocity, combined with the simultaneously measured systolic ejection time, CO and other advanced hemodynamic variables can be calculated, including estimations of preload, afterload, and contractility. Numerous studies have validated TED-derived CO against reference methods. Although the agreement of CO values between TED and the reference methods is limited (95% limits of agreement: median 4.2 L/min, interquartile range 3.3-5.0 L/min), TED has been shown to accurately follow changes of CO over time, making it a useful device for trend monitoring. TED can be used to guide perioperative intravascular volume substitution and therapy, with vasoactive or inotropic drugs. Various studies have demonstrated a reduced postoperative morbidity and shorter length of hospital stay in patients managed with TED compared with conventional clinical management, suggesting that it may be a valuable supplement to standard perioperative monitoring. We review not only the technical basis of this method and its clinical application but also its limitations, risks, and contraindications.