By Alexandros G. Sfakianakis,Anapafseos 5 Agios Nikolaos 72100 Crete,Greece,00302841026182,00306932607174
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Thursday, January 10, 2019
Kenya: Solar motorcycles take on Nairobi smog
from Climate Change Skeptic Blogs via hj on Inoreader http://bit.ly/2D25oO3
Bioleaching of heavy metals from harbor sediment using sulfur-oxidizing microflora acclimated from native sediment and exogenous soil
Abstract
The harbor sediment containing high concentration of heavy metals may pose serious impacts on the marine ecosystem and environmental quality. The bioleaching process has been considered as an environmentally friendly and cost-effective alternative for removing heavy metals from contaminated sediments. In this study, a series of experiments were performed to investigate the feasibility of bioleaching process for removing heavy metals from the contaminated harbor sediments. The performance of the bioleaching process inoculated with sulfur-oxidizing microflora acclimated from the native harbor sediment was compared with that acclimated from the exogenous soil. In the bioleaching experiment with inoculants from native sediment, the efficiency of Zn, Cu, Cr, Pb, and Ni (30 days) reached 39–100%, 21–94%, 8–63%, 5–74%, and 19–77%, respectively. While 59–100% of Zn, 22–100% of Cu, 0–95% of Cr, 0–100% of Pb, and 22–100% of Ni were respectively removed in the bioleaching experiment with inoculants from exogenous soil after 30 days of reaction time. The results show that the rate and efficiency of metal removal in the bioleaching process decreased with an increase of sediment solid content from 10 to 40 g/L. The efficiency of metal removal in the bioleaching process with inoculants from the native sediment was lower than those from the exogenous soil due to the bacterial activity. By the fractionation of metal in the harbor sediment, exchangeable, carbonate-bound, and Fe/Mn oxide-bound metals (mobile fractions) were found to be apparently reduced and even organic matter/sulfide-bound and residual metals (stable fractions) were slightly removed after the bioleaching experiment.
from Climate Change Skeptic Blogs via hj on Inoreader http://bit.ly/2RICgmV
Preparation and characterization of activated carbon produced from tannery solid waste applied for tannery wastewater treatment
Abstract
The removal of toxic compounds (azo dyes) from dyeing wastewater was investigated by an environmentally friendly activated carbon produced from solid waste generated in the tannery process, the cattle hair (CHW), activated with H3PO4 (AC-CHW), suggesting a life cycle extension for this material from leather processing. Preliminary tests with aqueous solutions containing Acid Brown 414 (AB-414) and Acid Orange 142 (AO-142) removed 71.06% and 73.05%, respectively. The activated carbon was characterized by zeta potential (ZP), functional groups (FTIR), elemental composition, sorbent specific surface area, and pore size distribution (BET/BJH). The specific surface area showed low values when compared to commercial activated carbon, but average pore diameter was higher, which facilitates the adsorption of larger and complex molecules, such as those present in real wastewaters. Through SEM and FTIR, the presence of the toxic compounds studied in the AC-CHW after sorption process was observed, where the results indicated that the functional groups of -CH=CH- participated in the removal process for these compounds. The removal efficiency obtained with AC-CHW was 51.94% and 49.73% for the dyeing wastewater containing AB-414 and AO-142, respectively. The obtained results open a promising via to use AC-CHW as efficient eco-friendly sorbent for the treatment of leather wastewater.
from Climate Change Skeptic Blogs via hj on Inoreader http://bit.ly/2M2RXjt
Magnetic Resonance Imaging
Osteosarcoma of the mandible
Niharika Bisht, Sankalp Singh, Samir Gupta, Harinder Pal Singh, Prabha Shankar Mishra, Deepak Mulajker
DOI:10.4103/ccij.ccij_6_18
Osteosarcomas comprise of a heterogeneous group of tumors with a predilection for involving long bones commonly. The jaw remains a rare site of involvement, and these tumors can be considered a distinct entity. The key for managing them lies in histological and radiological correlation for an early diagnosis. Surgery and chemotherapy remain the main modalities of treatment. We present a case of osteogenic sarcoma of the mandible that after radical treatment had local recurrence and distant metastasis.
http://www.ccij-online.org/currentissue.asp?sabs=y
Psammomatoid juvenile ossifying fibroma of maxilla
Jyotsna Naresh Bharti, Ashok Singh, Jitendra Singh Nigam
DOI:10.4103/ccij.ccij_8_18
Juvenile ossifying fibroma (JOF) is a rare variant of ossifying fibroma. JOF is classified into two distinct clinicopathological variants: Trabecular and psammomatoid JOF. Based on the age group involved, most common site of occurrence and clinical behavior, JOF differs from the larger group of ossifying fibromas. We report a case of psammomatoid JOF of maxilla in a 10-year-old female who presented with a swelling over the right side of the face.
http://www.ccij-online.org/currentissue.asp?sabs=y
Carcinosarcoma of the submandibular gland with a rhabdomyosarcoma component
Suma M Narayana, Smrita Singh, Rekha V Kumar
DOI:10.4103/ccij.ccij_83_18
Carcinosarcoma of the salivary gland is a rare and aggressive malignancy with a poor prognosis. These neoplasms are composed of malignant epithelial and mesenchymal elements. This report describes a new case of carcinosarcoma arising in the submandibular gland, which had a rhabdomyosarcoma component, without clinical or histological evidence of a preexisting pleomorphic adenoma. Till date, only two case reports have described the occurrence of carcinosarcoma with a rhabdomyosarcoma component in the salivary gland, to the best of our knowledge. Histological and immunohistochemical results are presented. The literature is reviewed, and the possible histogenesis and pathogenesis of carcinosarcoma (true malignant mixed tumor) of the salivary gland are briefly discussed.
http://www.ccij-online.org/currentissue.asp?sabs=y
Years with anxiety and headache
Mazaher Ramezani, Shima Jalalvandi, Zahra Torkchin, Masoud Sadeghi
DOI:10.4103/ccij.ccij_66_18
Pilocytic astrocytomas (PAs) account for 25% of all pediatric brain tumors and commonly occur in the first two decades of life. Recurrence and/or regrowth of residual tumors are not common and mostly occur within 4–5 years of the first surgery. Herein, we reported a 16-year-old male adolescent with neurological symptoms and signs that pathologic specimens confirmed the diagnosis of PA. The patient underwent 27 sessions of radiotherapy without surgery. After 5 years, at the age of 21, the patient readmitted with anxiety and headache and the recurrence of the same tumor with the same grade. We suggest follow-up of the patient after initial treatment for at least 5 years with considering any neurological symptoms including behavioral changes.
http://www.ccij-online.org/currentissue.asp?sabs=y
Apoptotic indices are useful in distinguishing between benign and malignant squamous lesions
Sheetal Arora, Deepshikha Rana, Indrani Dhawan, Rashmi Arora
DOI:10.4103/ccij.ccij_80_17
Background: The aim of the study was to evaluate the role of apoptotic index (AI) in premalignant and malignant squamous lesions of different sites on light microscopy. Materials and Methods: Retrospective study of 75 cases of premalignant and malignant squamous epithelial lesions of different sites was done. All slides were H and E stained, screened for apoptosis under ×40. AI was calculated as the number of apoptotic cells and apoptotic bodies, expressed as percentage of total number of tumor cells counted in each case. Results: On statistical analysis, it was found that the difference in the apoptotic indices in all the subgroups of dysplasia was not statistically significant. However, the significant statistical difference was found within the malignant group, P value between well-differentiated squamous cell carcinoma (SCC) and moderately differentiated SCC (MDSCC) was <0.0001. P value obtained between MDSCC and poorly differentiated SCC was 0.0006. Conclusion: We conclude that apoptotic indices are useful in distinguishing between benign and malignant squamous lesions. Several indices such as proliferating index (Ki-67) and AgNOR count are not routinely available in various hospitals, especially in developing countries. The advantage of this technique is that it can be calculated in routine H and E stained sections, and so it saves time. Although it is labor-intensive, it is cost-effective method which can benefit the patient as it correlates well with tumor aggressiveness and thereby increasing the prognosis of the patients.
http://www.ccij-online.org/currentissue.asp?sabs=y
Computed tomography-guided fine-needle aspiration and concurrent core biopsy
Rajashree Pradhan, Sajeeb Mondal, Subrata Pal, Mrinal Sikder, Biswajit Biswas
DOI:10.4103/ccij.ccij_81_17
Introduction: Fine-needle aspiration cytology (FNAC) is a simple, safe, and effective tool for cytological diagnosis of different neoplastic lesions. Computed tomography (CT)-guided core biopsy is also essential for tissue diagnosis. Aims and Objectives: The aim of this study is to assess the diagnostic value and limitations of fine-needle aspiration and core biopsy in diagnosis of intrathoracic lesions; we have done this retrospective study. Materials and Methods: In all 54 cases with mean age of 57.37 years, CT-guided FNAC and core biopsy were performed on same sittings. 20–22 G Chiba needle was used for FNAC, and core biopsy was performed by 18–20 G coaxial automated cutting needle. The cytological and histological evaluations were done in our cytology and histopathology laboratory. Complications were managed by pulmonologists. Results: On the evaluation of FNAC smears, diagnosis was done in 44 cases and 10 cases were inconclusive. In core biopsy, five cases were inconclusive. Most of the tumors were of epithelial origin (43 cases, 87.75%) and 95.59% cases were malignant in our series. Sensitivity and diagnostic accuracy of core biopsy (90.38% and 90.74, respectively) were higher than FNAC (84.62% and 85.18%, respectively). Conclusion: CT-guided core biopsy was more effective and accurate in diagnosis and tumor classification than FNAC in spite of higher complication rate.
http://www.ccij-online.org/currentissue.asp?sabs=y
Ultrasound-guided fine-needle aspiration cytology of head and neck masses
Abidemi Emmanuel Omonisi, Olufunso Simisola Aduayi, John Adetunji Omotayo, Ganiyu Olusola Akanbi, Olusola Olusoga Akute
DOI:10.4103/ccij.ccij_87_17
Background: A multidisciplinary approach to the evaluation of head and neck masses is crucial to achieving optimum patient care and enhancing diagnostic accuracy for definitive treatment. This is exemplified by the clinical and radiopathologic correlation of head and neck masses subjected to diagnostic evaluation using ultrasound-guided fine-needle aspiration cytology (FNAC) in a tertiary health institution. Subjects and Methods: A prospective study was carried out on 51 patients with head and neck lesions referred to the FNAC Clinic of the Department of Anatomic Pathology of Ekiti State University Teaching Hospital, Ado-Ekiti, Nigeria. The study was conducted over a period of 2 years between February 2014 and January 2016. The FNAC was done under imaging guidance with a 7.5 MHz ultrasound probe. Clinical, radiological, and pathological findings were correlated. The data were analyzed using SPSS version 15. Results: The study population consisted of 12 (23.5%) males and 39 (76.5%) females. The age range was 2–80 years with a mean age of 44.7 ± 18.4 years. A significant proportion (80.4%) of the masses was located in the anterior neck. Multinodular goiter (n = 22, 43.1%) was the predominant clinical diagnosis. On ultrasonography, the predominant echotexture of the masses was heterogeneous (n = 29, 56.9%), only 4 (7.84%) of the masses had internal calcifications while the predominant composition of the masses was a mixture of solid and cystic portions (n = 30, 58.8%). There was a strong radiopathologic correlation (Spearman correlation value of 0.910). Conclusion: Ultrasound-guided FNAC of head and neck masses provides a synergistic approach to patient care and should be encouraged in our setting for optimum diagnostic yields.
http://www.ccij-online.org/currentissue.asp?sabs=y
Latex-related symptoms and sensitization
Jandhyala Sridhar, Rahul Ray
DOI:10.4103/jmms.jmms_58_18
Background and Aim: Upsurge in usage of latex gloves over the last few decades, coupled with the proliferation of medical latex products at the workplace, has led to a higher incidence of latex-related symptoms among health-care workers (HCWs). This study aimed to assess the prevalence and associated factors of latex glove-related symptoms and sensitization among HCW at a multispecialty hospital. Materials and Methods: The study included all the paramedical personnel and nurses employed at a multispecialty hospital where powdered latex gloves were in use. Consenting participants were evaluated by a questionnaire for symptoms of latex allergy, followed by a skin prick test (SPT) for evaluating sensitization to latex allergen. Statistical Analysis Used: Mean, standard deviation, and Student's t-test were used for continuous data. Categorical data were analyzed using the Chi-square test. Odds ratios and 95% confidence intervals were calculated. Results: Latex glove-related symptoms were present in 25 (10.91%) HCWs. Symptoms suggestive of Type I latex allergy were reported in 11 (4.8%), while those of contact dermatitis were reported in 17 (7.42%) HCWs. Of the 229 HCWs, 37 (16.16%) had a personal history of atopy; 14 (6.11%) were SPT positive to latex allergen. Conclusions: In this study among Indian HCW, there was a significant correlation of latex glove-related symptoms with the duration of glove use, personal atopy, and SPT positivity to latex allergen. Questionnaire-based evaluation of allergic symptoms along with SPT positivity was found to be a useful identifier of true latex allergy.
http://www.marinemedicalsociety.in/currentissue.asp?sabs=y
Intravenous (IV) fluid resuscitation
Prabhakar Gupta, Kuldeep Kumar Ashta
DOI:10.4103/jmms.jmms_9_18
Intravenous (IV) fluid resuscitation, pioneered in 1832, is now one of the most common medical interventions in hospitalized patients. Up until the end of the 20th century, IV fluid prescriptions have been considered ancillary, benign interventions and rarely tested in good-quality randomized clinical trials (RCTs). Robust clinical research evidence emerging in the past decade and a half, however, has revealed counterintuitive findings. The emerging research has consistently demonstrated harm, including higher mortality, and questionable clinical benefits associated with protocolized aggressive fluid resuscitation, as espoused in the early goal-directed therapy. Conservative fluid management has been shown to be associated with better outcomes in most clinical settings. Recent RCTs have also revealed clinically relevant pharmacological differences between types of IV fluids, especially pertaining to predictable harms associated with some commonly used IV fluids. Concerns have emerged over risks of metabolic acidosis and renal failure associated with the use of normal saline. Balanced solutions have been found to be safe across a wide spectrum of conditions. Better understanding of the complex pathophysiology of sepsis and critical illnesses and recognition of newer concepts such as profound disruption of the endothelial glycocalyx layer leading to profound leakiness of vessels question the basic premise of injection of large quantities of IV fluids during resuscitation.
http://www.marinemedicalsociety.in/currentissue.asp?sabs=y
Introduction |
During the course of the past two centuries, due to a general absence of robust evidence, intravenous (IV) fluid use in resuscitation was largely guided by empirical institutional protocols or prescriber preferences.[1]
A major inflection point in the history of IV fluid resuscitation was the publication of early goal-directed therapy (EGDT) model of IV fluid resuscitation as incorporated in the Surviving Sepsis Campaign Guidelines (SSCG).[2] Although intended for use in sepsis, due to widespread popularity and endorsements, EGDT became a standard of care not just in sepsis but also in other critical illnesses necessitating fluid resuscitation.[3] EGDT popularized infusions of large quantities (in some instances measurable in gallons) of crystalloids, in an effort to achieve, untested, arbitrarily predetermined, fixed metrics such as 8 mmHg of central venous pressure (CVP).[4] Till date, there is no upper cutoff limit of dose of IV fluid to be infused within the first 6 h, prescribed in EGDT or SSCG.
Over the last decade, EGDT has been tested in several large, high-quality clinical trials and the results have been counterintuitive and consistent across various studies and diverse settings.[5],[6],[7]
In a patient-level meta-analysis of ProMISe, ARISE, and ProCESS, which analyzed data of 3723 patients at 138 centers, in seven countries spread over three continents, the use of EGDT versus usual care did not result in any difference in mortality at 90 days. EGDT was also associated with greater use of intensive care and cardiovascular support and treatment costs. Moreover, EGDT was not beneficial even in specific subgroups of more severely ill patients such as those with hyperlactatemia, hypotension with hyperlactatemia, or higher predicted risk of death.[8]
A review of basic research and clinically relevant newer insights into the complex pathophysiology of circulatory system and transmembrane fluid shifts during acute illnesses may tender some explanations and may help us understand the consistent, counterintuitive results of harm from aggressive IV fluid resuscitation as shown in recent high-quality randomized clinical trials (RCTs) and meta-analyses.
Resuscitation Physiology |
Classic model
Classic model of resuscitation physiology envisages (a) a circulatory system with "physical or mechanical plumbing" characteristics defined by forward and backward hydrostatic pressures, (b) the cardiac activity serving as the "motor" of the pump, (c) sympathetic activity, which may increase cardiac output and arterial and venous tones and pressures, and (d) compartment model of diffusion of fluids which presumes that only the capillaries and postcapillary venules permit transmembrane fluid flow.
These mechanisms were postulated to explain circulatory and fluid physiology in health and/or simplified deviations from healthy state. Clinical conditions meriting IV fluid resuscitation such as sepsis, burns, and trauma, however, have an exceedingly complex, dynamically changing circulatory, hemodynamic, endothelial, and neurohormonal pathophysiology.[9]
Current Approaches to Resuscitation Physiology |
Aggressive fluid resuscitation may have been predicated on the rather reductionist premise that hypotension in critical illnesses is a consequence of volume loss and that mechanically pumping large quantities of IV fluid on the venous side of the circulation may faithfully and incrementally be transformed into raised hydrostatic pressure and forward flow in the arterial circulation.
Robust RCTs in the past two decades have shown that this is not the case and a closer examination of certain key aspects of resuscitation physiology may illustrate the mechanisms of potential harm and lack of intended therapeutic gains of aggressive fluid therapy in resuscitation. A focused discussion of key aspects of resuscitation physiology specifically relevant to bolus IV fluid resuscitation is attempted below.
Venous system
The arterial system and the left side of the heart are usually the focus of deliberations in ischemic heart disease. Due to certain unique characteristics, however, the venous system acquires more significance in resuscitation physiology and critical illnesses. During resuscitation, for example, large quantities of fluids are directly injected into the venous system. Compliance of veins is 30-fold higher than arteries and the venous system accommodates 70% of the total blood volume as compared to only 18% in the arteries.[10]
Unstressed volume, stressed volume
The blood volume which can be accommodated in the venous system without exerting any hydrostatic pressure is the unstressed volume. The volume of blood, over and above the unstressed volume, which stretches the veins and results in the emergence of positive hydrostatic pressure in the venous system is called the stressed volume.[4]
Theoretically, when the heart is stopped (zero flow), the hydrostatic pressure exerted by the intravascular volume on the vasculature is called the mean circulatory filling pressure (MCFP).
Stressed volume in the venous system is the major contributor for the MCFP, which in turn is the major determinant of venous return. Venous return occurs when the MCFP, which normally is 8–10 mmHg, exceeds the CVP.[4]
Circulatory hemodynamic effects of intravenous fluid boluses
Due to a large capacitance and a constant compliance, the venous system can accommodate large IV infusion volumes resulting in relatively small increases in MCFP. Conversely, due to restraining effects of the pericardium and the cardiac cytoskeleton, the diastolic compliance of both ventricles rapidly reduces with increasing distending volumes resulting in relatively large and rapid increases in the CVP.[11]
Therefore, with bolus infusions, the CVP increases disproportionately faster than the MCFP, thereby reducing the gradient of blood flow from the venous system to the right atrium (the venous return).
The driving force for organ blood flow is the pressure difference between the mean arterial pressure and the CVP. Thus, a rapidly rising CVP (as might happen during IV bolus) not only reduces the gradient for venous return but also reduces forward blood flow through the organs.[11]
CVP is the major determinant of capillary blood flow. The higher the CVP, the lesser the capillary flow.[11]
Thus, we see that rapid infusion of fluid boluses may not improve circulatory hemodynamics and, on the contrary, may actually impede forward flow in the circulation and venous return.
Vasoplegia
A primary pathology in severe sepsis, septic shock, and critical illnesses is vasoplegia and not dehydration which may or may not be present as an epiphenomenon.[12]
Vasoplegia leads to arterial dilatation resulting in systemic hypotension. More importantly, there is profound venodilation, especially in the splanchnic and cutaneous vascular beds.
There is no mechanism by which IV fluid infusion can improve vasoplegia. Bolus IV fluid infusions in the setting of profound vasoplegia can however rapidly increase the unstressed volume and CVP, thereby reducing venous return and cardiac output. Vasoplegia improves either with vasopressors or with spontaneous homeostasis over time.
Cardiac Physiology |
Fluid administration will only result in increase of stroke volume (SV) when both of two conditions are met, namely (i) the fluid bolus increases the MCFP more than the CVP. We have seen in the preceding discussion that rapid fluid boluses are likely to raise the CVP more than the MCFP[13] and (ii) both ventricles are functioning on the ascending limb of the Frank–Starling curve.
Sepsis-associated myocardial dysfunction tends to flatten the Frank–Starling curve. Up to 50% of patients with sepsis may have systolic dysfunction.[14]
Furthermore, due to high prevalence of lifestyle diseases in the hospitalized population, left ventricular diastolic dysfunction is emerging as an important finding in patients with severe sepsis and septic shock.[15] Patients with diastolic dysfunction respond very poorly to fluid loading. In such patients, fluid challenges will result in increased cardiac filling pressures, increased pulmonary and venous hydrostatic pressures, increased release of natriuretic peptides, with minimal, if any rise in SV.[4],[16]
Endothelial and Microcirculatory Dysfunction |
There is a marked endothelial dysfunction in sepsis characterized by increased expression and activation of endothelial adhesion molecules, resulting in increased adhesion and activation of leukocytes and platelets, and the net effect is marked leakiness and heterogeneous abnormalities in microcirculatory blood flow.[9],[17],[18],[19]
Furthermore, aggressive fluid therapy leads to increased cardiac filling pressures which results in release of natriuretic peptides. Natriuretic peptides profoundly disrupt the glycocalyx structure and function, leading to increased vascular leakiness.[18],[19] Increased natriuretic peptides also reduce lymphatic drainage by reducing lymphatic propulsive motor activity.[20]
Fluid Responsiveness |
A significant finding from fluid resuscitation studies over the years is that only 50% of the patients are fluid responders.
Here, three key concepts need to be emphasized.
- There is no physiologic rationale for bolus IV fluid infusions in fluid nonresponders
- Even in the fluid responders, once the optimal preload is achieved, any additional increase in preload does not result in any appreciable increase in SV and results in harm, in that, right atrial pressure (RAP) rapidly increases resulting in increased pulmonary and venous hydrostatic pressures, release of natriuretic peptides resulting in shift of fluid into the interstitial tissue causing pulmonary and tissue edema. In addition, due to sepsis-associated myocardial dysfunction, these adverse hemodynamic effects may appear at a lower fluid dose, even before the optimal preload is achieved[20]
- Disproportionately large fraction of the infused fluid will promptly leak out into the extravascular space. In healthy volunteers, of the infused volumes of crystalloids, only 15% remains in the intravascular space at 3 h. Due to endothelial disruption, in sepsis, less than 5% of a crystalloid bolus remains in the intravascular space at 1 h[21]
Thus, the intended hemodynamic gains of IV fluid bolus, even in fluid responders, are short-lived, and most of the infused bolus will rapidly accumulate in the interstitial space leading to tissue edema.
Implications on Intravenous Fluid Therapeutics |
It is obvious from the above discussion that aggressive, goal-directed IV fluid resuscitation algorithmized to meet externally decided static metrics such as CVP is fraught with pitfalls. It may be noted that while residents and house officers may have a liking for customized algorithms, these, as is the case of EGDT, have been proven to be harmful. Rather, under the following subheadings, we propose suggestions, based on the emerging evidence, on caution and discretion in the use of volumes and types of IV fluids in day-to-day settings with an aim to reduce harm arising from individual fluid prescriptions.
Dose of Fluid Therapy |
Initial bolus
Ideally, the initial fluid bolus should aim to replace the extant volume lost and the anticipated ongoing losses in the next few hours.
Many conditions with hypotension, however, may not be fluid depleted states. In sepsis, the dominant physiology is of profound vasoplegia, vascular leakiness, and fluid redistribution, rather than dehydration, unless there are other associated causes of fluid loss such as fever and poor oral intake.
Till date, the best trial comparing the effects of IV fluid boluses with no boluses in critical illness is the landmark Fluid Expansion as Supportive Therapy trial (FEAST). In this multicenter RCT involving 3141 children with severe sepsis and demonstrated evidence of fluid depletion, any fluid boluses, when compared to no fluid bolus, were strongly associated with higher mortality and morbidity. The statistical significance was of such magnitude that the trial had to be stopped on ethical grounds.[22] These findings are congruent with other high-quality clinical research in fluid therapeutics emerging over the past decade.[5],[6],[7],[8]
The fact that, in the FEAST trial subjects, even in patients with proven volume depletion, IV fluid boluses, when compared to no bolus resulted in higher mortality, should compel us to revisit the widely held premise that IV fluid therapy is a central pillar of management of critical illnesses.[4]
Considering the above, a reasonable approach may be using a therapeutic trial of a small bolus, approximately 250–500 mL of a crystalloid, in the setting of systolic hypotension and oliguria. If the blood pressure does not respond, consideration should be given for addressing possible concomitant vasoplegia with vasopressors. If the initial bolus has failed, repeat "fluid challenges" have no role and may prove counterproductive.[4],[23]
Maintenance fluids
After initial fluid resuscitation, a subset of patients, especially those who have poor oral intake, may need maintenance fluids, with an aim to preserving the extracellular volume while maintaining a normal electrolyte balance.
However, in actual practice, maintenance fluids are often routinely prescribed. Some of these patients may have already received a large positive balance in the acute resuscitation period. Subjecting them to further daily prescriptions of maintenance fluids without compelling indications may lead to a large cumulative fluid balance over several days.[24],[25]
In a high-quality, prospective RCT, conservative late fluid management was associated with lesser morbidity and mortality as compared to liberal fluid policy.[26]
Maintenance fluids should only be prescribed if there are clear indications. Maintenance fluids should be actively stopped if there is no compelling indication for ongoing fluid administration. The quantity of maintenance fluids should be estimated individually in each patient with an emphasis on frequent audits of cumulative fluid balance since admission, aiming to avoid positive balance.[1],[26]
Type of Fluid Therapy |
The composition of IV fluids may have a bearing on context-specific outcomes, especially related to potential harm. Different types of IV fluids should be prescribed after factoring in patient-specific and context-specific differences.[1],[23]
Colloids
The findings of the landmark saline versus albumin fluid evaluation (SAFE) and FEAST studies assuaged concerns about safety of albumin raised in a Cochrane review. However, the data did not reveal any significant advantage of albumin over saline, thereby challenging long-held concepts about the advantages of albumin as a resuscitation solution.[27],[28]
In volume-depleted states requiring resuscitation, it appears that albumin, which is more expensive and less easily available, offers no distinct advantages over saline in patient-centered outcomes.
Semisynthetic colloids
A range of semisynthetic colloids including HES solutions, succinylated gelatin, and dextran solutions were developed to offset the constraints of cost and availability of albumin. However, research has revealed clinically relevant safety concerns with the use of semi-synthetic colloids.[29],[30],[31]
In view of the lack of clinical benefit, evidence of potential nephrotoxicity, decreased availability, and higher costs, the inclusion of semisynthetic colloids in fluid resuscitation protocols in critically ill patients is questionable.
Crystalloids
Normal saline
Worldwide, sodium chloride (normal saline) is the most commonly used crystalloid solution.
Due to the strong ion difference of 0.9% saline being zero, administration of large quantities of normal saline leads to hyperchloremic metabolic acidosis.
The hyperchloremic metabolic acidosis related to large volume bolus infusion of normal saline may lead to immune and renal dysfunction, including reduced renal blood flow, electrolyte disturbances, acute kidney injury, renal replacement therapy utilization, postoperative infections, acidosis investigations, and costs.[32],[33]
Hence, normal saline should not be the first choice of IV fluid in most critical illnesses necessitating IV fluid resuscitation. Normal saline may be an appropriate choice in conditions associated with alkalosis such as dehydration resulting from protracted emesis. To avoid the potential hypotonicity associated with balanced solutions, normal saline may be the preferred choice among maintenance fluids.[23]
Balanced solutions
Crystalloids designed to have a pH and chemical composition similar to extracellular fluid are called "balanced" or "physiologic" solutions. The most widely used of such solutions are Hartmann's and Ringer's solutions and their derivatives. However, none of these solutions achieve the true composition of extracellular fluid.
Due to a sodium concentration lower than the extracellular fluid, balanced solutions are hypotonic. To offset the instability of bicarbonate-containing balanced solutions in plastic containers, other anions, such as lactate, acetate, gluconate, and malate are used.
Administration of large quantities of balanced solutions may theoretically lead to hyperlactatemia, metabolic alkalosis, and hypotonicity (with compounded sodium lactate) and cardiotoxicity (with acetate). The calcium contained in some balanced solutions may lead to production of microthrombi when co-administered with citrate-containing red-cell transfusions.[23]
However, when tested in a wide spectrum of clinical settings, among all IV fluids, balanced solutions have shown the best safety profile including burns, diabetic ketoacidosis, and trauma and patients undergoing surgery.[34],[35],[36],[37]
Conclusions |
The physiology of sepsis and other similar critical illnesses is dynamically dysfunctional and dominated by marked vascular leakiness, myocardial depression, and profound vasoplegia. Most of the injected IV fluid rapidly leaks into the interstitial compartment, even in healthy individuals, and more promptly and profoundly so in critically ill patients.
The findings of FEAST, ProMISe, ProCESS, ARISE, PRISM, and CHEST are particularly important because they reveal potential harm or lack of benefit of widely practiced and advocated aggressive fluid resuscitation policies such as espoused in the EGDT protocol. The evidence is relatively robust, congruent across various studies, and in line with newer understanding of the complex, biologically dynamic physiology of acute illnesses.
These vital findings of high-quality clinical research emerging in the preceding two decades represent a paradigm change in our understanding of fluid therapeutics and critical illness physiology. This paradigm shift should be discussed widely so that the newly recognized potential harms related to the extant practice of algorithmized aggressive fluid resuscitation may be mitigated and patients may benefit with a more informed and judicious use of IV fluids in sepsis and critical illnesses.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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