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Current Opinion in Anaesthesiology Feb 2015Hypercapnia is a central component of diverse respiratory disorders, while 'permissive hypercapnia' is frequently used in ventilatory strategies for patients with severe... (Review)
Review
PURPOSE OF REVIEW
Hypercapnia is a central component of diverse respiratory disorders, while 'permissive hypercapnia' is frequently used in ventilatory strategies for patients with severe respiratory failure. This review will present data from recent studies relating to hypercapnia, focusing on issues that are of importance to anesthesiologists caring for the surgical and/or critically ill patient.
RECENT FINDINGS
Protective ventilatory strategies involving permissive hypercapnia are widely used in patients with severe respiratory failure, particularly in acute respiratory distress syndrome, status asthmaticus, chronic obstructive pulmonary disease and neonatal respiratory failure. The physiologic effects of hypercapnia are increasingly well understood, and important recent insights have emerged regarding the cellular and molecular mechanisms of action of hypercapnia and acidosis. Acute hypercapnic acidosis is protective in multiple models of nonseptic lung injury. These effects are mediated in part through inhibition of the NF-κB pathway. Hypercapnia-mediated NF-κB inhibition may also explain several deleterious effects, including delayed epithelial wound healing and decreased bacterial killing, which has been demonstrated to cause worse lung injury in prolonged untreated pneumonia models.
SUMMARY
The mechanisms of action of hypercapnia and acidosis continue to be elucidated, and this knowledge is central to determining the safety and therapeutic utility of hypercapnia in protective lung ventilatory strategies.
Topics: Acidosis; Humans; Hypercapnia; Intraoperative Complications; Respiration, Artificial; Respiratory Insufficiency
PubMed: 25500498
DOI: 10.1097/ACO.0000000000000151 -
Journal of Animal Science Aug 2020Acute and subacute ruminal acidosis (SARA) are common nutritional problems in both beef and dairy cattle. Therefore, the objective of this review is to describe how... (Review)
Review
Acute and subacute ruminal acidosis (SARA) are common nutritional problems in both beef and dairy cattle. Therefore, the objective of this review is to describe how ruminal Gram-negative bacteria could contribute to the pathogenesis of ruminal acidoses, by releasing lipopolysaccharides (LPS; a component of their cell wall) in the ruminal fluid. When cattle consume excessive amounts of highly fermentable carbohydrates without prior adaptation, normal fermentation become disrupted. The fermentation of these carbohydrates quickly decreases ruminal pH due to the accumulation of short-chain fatty acids and lactate in the rumen. As a consequence, ruminal epithelium may be damaged and tissue function could be impaired, leading to a possible translocation of pathogenic substances from the rumen into the bloodstream. Such changes in fermentation are followed by an increase in Gram-positive bacteria while Gram-negative bacteria decrease. The lyses of Gram-negative bacteria during ruminal acidosis increase LPS concentration in the ruminal fluid. Because LPS is a highly proinflammatory endotoxin in the circulatory system, past studies have raised concerns regarding ruminal LPS contribution to the pathogenesis of ruminal acidosis. Although animals that undergo these disorders do not always have an immune response, recent studies showed that different Gram-negative bacteria have different LPS composition and toxicity, which may explain the differences in immune response. Given the diversity of Gram-negative bacteria in the rumen, evaluating the changes in the bacterial community during ruminal acidosis could be used as a way to identify which Gram-negative bacteria are associated with LPS release in the rumen. By identifying and targeting ruminal bacteria with possible pathogenic LPS, nutritional strategies could be created to overcome, or at least minimize, ruminal acidosis.
Topics: Acidosis; Animals; Cattle; Cattle Diseases; Diet; Epithelium; Fatty Acids, Volatile; Fermentation; Gram-Negative Bacteria; Hydrogen-Ion Concentration; Lipopolysaccharides; Rumen
PubMed: 32761212
DOI: 10.1093/jas/skaa248 -
Seminars in Respiratory and Critical... Oct 2023Disorders of acid-base status are common in the critically ill and prompt recognition is central to clinical decision making. The bicarbonate/carbon dioxide buffer...
Disorders of acid-base status are common in the critically ill and prompt recognition is central to clinical decision making. The bicarbonate/carbon dioxide buffer system plays a pivotal role in maintaining acid-base homeostasis, and measurements of pH, PCO, and HCO are routinely used in the estimation of metabolic and respiratory disturbance severity. Hypoventilation and hyperventilation cause primary respiratory acidosis and primary respiratory alkalosis, respectively. Metabolic acidosis and metabolic alkalosis have numerous origins, that include alterations in acid or base intake, body fluid losses, abnormalities of intermediary metabolism, and renal, hepatic, and gastrointestinal dysfunction. The concept of the anion gap is used to categorize metabolic acidoses, and urine chloride excretion helps define metabolic alkaloses. Both the lungs and kidneys employ compensatory mechanisms to minimize changes in pH caused by various physiologic and disease disturbances. Treatment of acid-base disorders should focus primarily on correcting the underlying cause and the hemodynamic and electrolyte derangements that ensue. Specific therapies under certain conditions include renal replacement therapy, mechanical ventilation, respiratory stimulants or depressants, and inhibition of specific enzymes in intermediary metabolism disorders.
Topics: Humans; Acid-Base Imbalance; Hydrogen-Ion Concentration; Acid-Base Equilibrium; Acidosis; Alkalosis; Carbon Dioxide
PubMed: 37369215
DOI: 10.1055/s-0043-1770341 -
The Veterinary Clinics of North... Nov 2017Clinical rumen acidosis is an important cause of morbidity and mortality in both large and small ruminants. Feeding and management practices that lead to the consumption... (Review)
Review
Clinical rumen acidosis is an important cause of morbidity and mortality in both large and small ruminants. Feeding and management practices that lead to the consumption of large amounts of readily fermentable carbohydrates precipitate clinical disease. The fermentation of carbohydrates into volatile fatty acids and lactate causes acidosis (local and systemic), rumen ulceration, cardiovascular compromise, and organ dysfunction. Animals affected with acidosis can suffer from numerous sequelae. Treatment of animals with clinical rumen acidosis is focused on addressing plasma volume deficits, correcting acid-base disturbances, and restoring a normal rumen microenvironment.
Topics: Acidosis; Animals; Rumen; Ruminants; Stomach Diseases
PubMed: 28743471
DOI: 10.1016/j.cvfa.2017.06.003 -
QJM : Monthly Journal of the... Aug 2019
Topics: Acetaminophen; Acidosis; Aged; Analgesics, Non-Narcotic; Humans; Male; Pain Management; Pyrrolidonecarboxylic Acid
PubMed: 31086977
DOI: 10.1093/qjmed/hcz107 -
European Journal of Clinical Nutrition Aug 2020Not all metabolic acidosis is associated with an elevated chloride replacing the low bicarbonate concentration. When other acids, usually non-Cl organic acids are... (Review)
Review
Not all metabolic acidosis is associated with an elevated chloride replacing the low bicarbonate concentration. When other acids, usually non-Cl organic acids are introduced into the blood an "Anion Gap" metabolic acidosis exists. The serum anion gap is calculated as [Na+] - ([Cl] + [HCO]) = Unmeasured anions - Unmeasured cations. The normal gap is mostly due to negatively charged albumin: (Normal range: 8-12 meq/l) as the unmeasured anions, since albumin is usually reported in grams per liter (not meq/l). For diagnostic purposes, calculating the serum anion gap allows determination of coexisting acid-base processes in a patient. Assuming a 1:1 fall in bicarbonate compared with rise in anion gap in a usual gap acidosis, one can compare the Δ anion Gap/ΔHCO: Δ gap = observed anion gap - normal anion gap and the Δ HCO = normal HCO - observed HCO. A ratio of 1 suggests a simple anion gap acidosis; if <1 a superimposed non-gap acidosis is lowering HCO and if >1 a superimposed metabolic alkalosis is raising HCO. Comparing the anion gap and osmolar gap can narrow the differential diagnosis to include toxic alcohol ingestions with acidic metabolites such as ethylene glycol and methanol. Not all metabolic acidosis is associated with an elevated chloride replacing the low bicarbonate concentration. When other acids, usually non-Cl organic acids are introduced into the blood an "Anion Gap" metabolic acidosis exists. This review will consider the generation of anion-gap acidoses through case discussions.
Topics: Acid-Base Equilibrium; Acidosis; Anions; Humans
PubMed: 32873962
DOI: 10.1038/s41430-020-0685-5 -
Pediatrics in Review Nov 2017
Review
Topics: Acidosis, Renal Tubular; Diagnosis, Differential; Humans
PubMed: 29093127
DOI: 10.1542/pir.2016-0231 -
The Veterinary Clinics of North... Mar 2017Respiratory acidosis, or primary hypercapnia, occurs when carbon dioxide production exceeds elimination via the lung and is mainly owing to alveolar hypoventilation.... (Review)
Review
Respiratory acidosis, or primary hypercapnia, occurs when carbon dioxide production exceeds elimination via the lung and is mainly owing to alveolar hypoventilation. Concurrent increases in Paco, decreases in pH and compensatory increases in blood HCO concentration are associated with respiratory acidosis. Respiratory acidosis can be acute or chronic, with initial metabolic compensation to increase HCO concentrations by intracellular buffering. Chronic respiratory acidosis results in longer lasting increases in renal reabsorption of HCO. Alveolar hypoventilation and resulting respiratory acidosis may also be associated with hypoxemia, especially evident when patients are inspiring room air (20.9% O).
Topics: Acid-Base Imbalance; Acidosis, Respiratory; Algorithms; Animals; Carbon Dioxide; Hypercapnia
PubMed: 27939862
DOI: 10.1016/j.cvsm.2016.10.012 -
The Veterinary Clinics of North... Nov 2017Ruminal acidosis and ruminal bloat represent the most common digestive disorders in feedlot cattle. Ruminants are uniquely adapted to digest and metabolize a large range... (Review)
Review
Ruminal acidosis and ruminal bloat represent the most common digestive disorders in feedlot cattle. Ruminants are uniquely adapted to digest and metabolize a large range of feedstuffs. Although cattle have the ability to handle various feedstuffs, disorders associated with altered ruminal fermentation can occur. Proper ruminal microorganism adaptation and a consistent substrate (ration) help prevent digestive disorders. Feed bunk management, sufficient ration fiber, consistent feed milling, and appropriate response to abnormal weather are additional factors important in prevention of digestive disorders. When digestive disorders are suspected, timely diagnosis is imperative.
Topics: Acidosis; Animal Feed; Animals; Cattle; Cattle Diseases; Diet; Fermentation; Hydrogen-Ion Concentration; Rumen; Stomach Diseases
PubMed: 28823879
DOI: 10.1016/j.cvfa.2017.06.005 -
Deutsche Medizinische Wochenschrift... Nov 2020Acid-base disorders due to different etiologies are frequently encountered in daily clinical practice and may result in life-threatening situations. Basic knowledge of...
Acid-base disorders due to different etiologies are frequently encountered in daily clinical practice and may result in life-threatening situations. Basic knowledge of the diagnostic and therapeutic approach of acid-base disorders is therefore essential for every clinician. Acid-base disorders should be treated according to their underlying etiology. Therefore, diagnosis of the underlying etiology is the critical step in the process of care for patients with acid-base disorders. Undirected buffering with HCO should be avoided, since the application of HCO might lead to severe side effects. A strict diagnostic pathway for the diagnosis of acid-base disorders is required, which should be vigorously applied:- analysis of the pH to classify acidemia or alkalemia- analysis of pCO and HCO to classify the primary acid base disorder- analysis of the adequate regulation in order to detect additional acid-base disorders- analysis of the anion gap and the relationship of the anion gap vs. the change in HCO to detect further metabolic disordersMetabolic acidosis can be divided into two main etiologies:- acidosis with addition of acid with increased anion gap,- acidosis with loss of HCO with normal anion gap.
Topics: Acid-Base Equilibrium; Acidosis; Bicarbonates; Humans
PubMed: 33142331
DOI: 10.1055/a-0670-6038