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Lin LT, Chen JT, Tai MC, Chen YH, Chen CL, Pao SI, Hsu CR, Liang CM. Protective effects of hypercapnic acidosis on Ischemia-reperfusion-induced retinal injury. PLoS One 2019; 14:e0211185. [PMID: 30682118 PMCID: PMC6347245 DOI: 10.1371/journal.pone.0211185] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 01/08/2019] [Indexed: 11/18/2022] Open
Abstract
Ischemia–reperfusion (I/R) injury is associated with numerous retinal diseases, such as diabetic retinopathy, acute glaucoma, and other vascular retinopathies. Hypercapnic acidosis (HCA) has a protective effect on lung, myocardial, and central nervous system ischemic injury models. However, no study has evaluated its protective effects in an experimental retinal I/R injury model. In this study, retinal I/R injury was induced in Sprague Dawley rats by elevating the intraocular pressure to 110 mmHg for 60 minutes. HCA was induced before and after the injury. After 24 hours, the terminal dUTP nick end labeling assay was performed. Moreover, the ratios of cleaved caspase-3/total caspase-3, phosphorylated IκB/IκB, and phosphorylated p38 were measured through Western blotting. After 7 days, the rats’ aqueous humor was analyzed. In addition, electroretinography and retinal thickness measurement were performed in the rats. Moreover, the retinal neural cell line RGC-5 was exposed to 500 μM H2O2 for 24 hours to induce a sustained oxidative stress in vitro. The effects of HCA were evaluated by comparing oxidative stress, MAPK signals, NF-κB signals, survival rates, and apoptosis rates in the RGC-5 cells before and after H2O2 exposure. We further investigated whether the potent I/R-protective heat shock protein (HSP) 32 contribute to protective effects of HCA. Our results indicated that HCA has protective effects against retinal I/R injury both in vivo and in vitro, at multiple levels, including antiapoptotic, anti-inflammatory, antioxidative, and functional retinal cell protection. Further research clarifying the role of HCA in retinal I/R injury prevention and treatment is warranted.
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Affiliation(s)
- Le-Tien Lin
- Department of Ophthalmology, Tri-Service General Hospital Songshan Branch, National Defense Medical Center, Taipei, Taiwan, Republic of China
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | - Jiann-Torng Chen
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
- Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China
- * E-mail: (CML); (JTC); (YHC)
| | - Ming-Cheng Tai
- Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | - Yi-Hao Chen
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
- Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China
- * E-mail: (CML); (JTC); (YHC)
| | - Ching-Long Chen
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
- Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | - Shu-I Pao
- Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | - Cherng Ru Hsu
- Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | - Chang-Min Liang
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
- Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China
- Graduate Institute of Aerospace and Undersea Medicine, National Defense Medical Center, Taipei, Taiwan, Republic of China
- * E-mail: (CML); (JTC); (YHC)
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2
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Mise au point sur les conséquences hémodynamiques de l’acidose lactique dans les états de choc. MEDECINE INTENSIVE REANIMATION 2017. [DOI: 10.1007/s13546-017-1262-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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3
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Doty AC, Zhang Y, Weinstein DG, Wang Y, Choi S, Qu W, Mittal S, Schwendeman SP. Mechanistic analysis of triamcinolone acetonide release from PLGA microspheres as a function of varying in vitro release conditions. Eur J Pharm Biopharm 2016; 113:24-33. [PMID: 27865933 DOI: 10.1016/j.ejpb.2016.11.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 10/29/2016] [Accepted: 11/04/2016] [Indexed: 10/20/2022]
Abstract
In vitro tests for controlled release PLGA microspheres in their current state often do not accurately predict in vivo performance of these products during formulation development. Here, we introduce a new mechanistic and multi-phase approach to more clearly understand in vitro-in vivo relationships, and describe the first "in vitro phase" with the model drug, triamcinolone acetonide (Tr-A). Two microsphere formulations encapsulating Tr-A were prepared from PLGAs of different molecular weights and end-capping (18kDa acid-capped and 54kDa ester-capped). In vitro release kinetics and the evidence for controlling mechanisms (i.e., erosion, diffusion, and water-mediated processes) were studied in four release media: PBST pH 7.4 (standard condition), PBST pH 6.5, PBS+1.0% triethyl citrate (TC), and HBST pH 7.4. The release mechanism in PBST was primarily polymer erosion-controlled as indicated by the similarity of release and mass loss kinetics. Release from the low MW PLGA was accelerated at low pH due to increased rate of hydrolysis and in the presence of the plasticizer TC due to slightly increased hydrolysis and much higher diffusion in the polymer matrix. TC also increased release from the high MW PLGA due to increased hydrolysis, erosion, and diffusion. This work demonstrates how in vitro conditions can be manipulated to change not only rates of drug release from PLGA microspheres but also the mechanism(s) by which release occurs. Follow-on studies in the next phases of this approach will utilize these results to compare the mechanistic data of the Tr-A/PLGA microsphere formulations developed here after recovery of microspheres in vivo. This new approach based on measuring mechanistic indicators of release in vitro and in vivo has the potential to design better, more predictive in vitro release tests for these formulations and potentially lead to mechanism-based in vitro-in vivo correlations.
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Affiliation(s)
- Amy C Doty
- Department of Pharmaceutical Sciences and the Biointerfaces Institute, University of Michigan, North Campus Research Complex, 2800 Plymouth Road, Ann Arbor, MI 48109, United States; Discovery Pharmaceutical Sciences, Pharmaceutical Sciences & Clinical Supply, Merck Sharp and Dohme Corp, 33 Avenue Louis Pasteur, Boston, MA 02115, United States(1)
| | - Ying Zhang
- Department of Pharmaceutical Sciences and the Biointerfaces Institute, University of Michigan, North Campus Research Complex, 2800 Plymouth Road, Ann Arbor, MI 48109, United States; 3M Critical & Chronic Care Solutions Division, 3M Center, St. Paul, MN 55144, United States(1)
| | - David G Weinstein
- Department of Pharmaceutical Sciences and the Biointerfaces Institute, University of Michigan, North Campus Research Complex, 2800 Plymouth Road, Ann Arbor, MI 48109, United States
| | - Yan Wang
- Food and Drug Administration, Center for Drug Evaluation and Research, Office of Generic Drugs, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States
| | - Stephanie Choi
- Food and Drug Administration, Center for Drug Evaluation and Research, Office of Generic Drugs, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States
| | - Wen Qu
- Food and Drug Administration, Center for Drug Evaluation and Research, Office of Generic Drugs, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States
| | - Sachin Mittal
- Sterile Formulation Sciences, Pharmaceutical Sciences & Clinical Supply, Merck Sharp and Dohme Corp, 2000 Galloping Hill Road, Kenilworth, NJ 07033, United States
| | - Steven P Schwendeman
- Department of Pharmaceutical Sciences and the Biointerfaces Institute, University of Michigan, North Campus Research Complex, 2800 Plymouth Road, Ann Arbor, MI 48109, United States; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, United States.
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4
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Kimmoun A, Novy E, Auchet T, Ducrocq N, Levy B. Hemodynamic consequences of severe lactic acidosis in shock states: from bench to bedside. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2015; 19:175. [PMID: 25887061 PMCID: PMC4391479 DOI: 10.1186/s13054-015-0896-7] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Lactic acidosis is a very common biological issue for shock patients. Experimental data clearly demonstrate that metabolic acidosis, including lactic acidosis, participates in the reduction of cardiac contractility and in the vascular hyporesponsiveness to vasopressors through various mechanisms. However, the contributions of each mechanism responsible for these deleterious effects have not been fully determined and their respective consequences on organ failure are still poorly defined, particularly in humans. Despite some convincing experimental data, no clinical trial has established the level at which pH becomes deleterious for hemodynamics. Consequently, the essential treatment for lactic acidosis in shock patients is to correct the cause. It is unknown, however, whether symptomatic pH correction is beneficial in shock patients. The latest Surviving Sepsis Campaign guidelines recommend against the use of buffer therapy with pH ≥7.15 and issue no recommendation for pH levels <7.15. Furthermore, based on strong experimental and clinical evidence, sodium bicarbonate infusion alone is not recommended for restoring pH. Indeed, bicarbonate induces carbon dioxide generation and hypocalcemia, both cardiovascular depressant factors. This review addresses the principal hemodynamic consequences of shock-associated lactic acidosis. Despite the lack of formal evidence, this review also highlights the various adapted supportive therapy options that could be putatively added to causal treatment in attempting to reverse the hemodynamic consequences of shock-associated lactic acidosis.
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Affiliation(s)
- Antoine Kimmoun
- CHU Nancy, Service de Réanimation Médicale Brabois, Pole Cardiovasculaire et Réanimation Médicale, Hôpital de Brabois, Vandoeuvre-les-Nancy, 54511, France. .,Université de Lorraine, Nancy, 54000, France. .,INSERM U1116, Groupe Choc, Faculté de Médecine, Vandoeuvre-les-Nancy, 54511, France.
| | - Emmanuel Novy
- CHU Nancy, Service de Réanimation Médicale Brabois, Pole Cardiovasculaire et Réanimation Médicale, Hôpital de Brabois, Vandoeuvre-les-Nancy, 54511, France. .,Université de Lorraine, Nancy, 54000, France.
| | - Thomas Auchet
- CHU Nancy, Service de Réanimation Médicale Brabois, Pole Cardiovasculaire et Réanimation Médicale, Hôpital de Brabois, Vandoeuvre-les-Nancy, 54511, France.
| | - Nicolas Ducrocq
- CHU Nancy, Service de Réanimation Médicale Brabois, Pole Cardiovasculaire et Réanimation Médicale, Hôpital de Brabois, Vandoeuvre-les-Nancy, 54511, France.
| | - Bruno Levy
- CHU Nancy, Service de Réanimation Médicale Brabois, Pole Cardiovasculaire et Réanimation Médicale, Hôpital de Brabois, Vandoeuvre-les-Nancy, 54511, France. .,Université de Lorraine, Nancy, 54000, France. .,INSERM U1116, Groupe Choc, Faculté de Médecine, Vandoeuvre-les-Nancy, 54511, France.
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Nardelli L, Rzezinski A, Silva J, Maron-Gutierrez T, Ornellas D, Henriques I, Capelozzi V, Teodoro W, Morales M, Silva P, Pelosi P, Garcia C, Rocco P. Effects of acute hypercapnia with and without acidosis on lung inflammation and apoptosis in experimental acute lung injury. Respir Physiol Neurobiol 2015; 205:1-6. [DOI: 10.1016/j.resp.2014.09.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/04/2014] [Accepted: 09/14/2014] [Indexed: 12/24/2022]
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6
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The Sick Neonate With Cardiac Disease. CLINICAL PEDIATRIC EMERGENCY MEDICINE 2011. [DOI: 10.1016/j.cpem.2011.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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7
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Sodium bicarbonate administration and outcome in preterm infants. J Pediatr 2010; 157:684-7. [PMID: 20580021 DOI: 10.1016/j.jpeds.2010.05.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Revised: 04/22/2010] [Accepted: 05/12/2010] [Indexed: 10/19/2022]
Abstract
The short-term outcomes of sodium bicarbonate therapy in preterm infants were investigated by retrospective analysis of 165 of 984 infants who received sodium bicarbonate. The infants treated with sodium bicarbonate were more immature and had greater severity of illness and more adverse outcomes. Sodium bicarbonate therapy did not improve the blood pH.
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8
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Harsha SS, Grischkowsky D. Terahertz (Far-Infrared) Characterization of Tris(hydroxymethyl)aminomethane Using High-Resolution Waveguide THz-TDS. J Phys Chem A 2010; 114:3489-94. [DOI: 10.1021/jp911135u] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- S. Sree Harsha
- School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, Oklahoma 74078
| | - D. Grischkowsky
- School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, Oklahoma 74078
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9
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Caples SM, Rasmussen DL, Lee WY, Wolfert MZ, Hubmayr RD. Impact of buffering hypercapnic acidosis on cell wounding in ventilator-injured rat lungs. Am J Physiol Lung Cell Mol Physiol 2008; 296:L140-4. [PMID: 18996901 DOI: 10.1152/ajplung.90339.2008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We measured the effects of raising perfusate pH on ventilator-induced cell wounding and repair in ex vivo mechanically ventilated hypercapnic rat lungs. Lungs were randomized to one of three perfusate groups: 1) unbuffered hypercapnic acidosis, 2) bicarbonate-buffered hypercapnia, or 3) tris-hydroxymethyl aminomethane (THAM)-buffered hypercapnia. The membrane-impermeant label propidium iodide was added to the perfusate either during or after injurious ventilation providing a means to subsequently identify transiently wounded and permanently wounded cells in optical sections of subpleural alveoli. Normalizing perfusate pH in hypercapnic preparations attenuated ventilator-induced cell injury, particularly in THAM-buffered preparations. This was observed despite greater amounts of edema and impaired lung mechanics compared with other treatment groups. Protective effects of buffering of hypercapnic acidosis on injury and repair were subsequently confirmed in a cell scratch model. We conclude that buffering of hypercapnic acidosis attenuates plasma cell injury induced by mechanical hyperinflation.
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Affiliation(s)
- Sean M Caples
- Thoracic Diseases Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
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10
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Abstract
Common clinical practices often are unsupported by experimental evidence. One example is the administration of sodium bicarbonate to neonates. Despite a long history of widespread use, objective evidence that administration of sodium bicarbonate improves outcomes for patients in cardiopulmonary arrest or with metabolic acidosis is lacking. Indeed, there is evidence that this therapy is detrimental. This review examines the history of sodium bicarbonate use in neonatology and the evidence that refutes the clinical practice of administering sodium bicarbonate during cardiopulmonary resuscitation or to treat metabolic acidosis in the NICU.
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Affiliation(s)
- Judy L Aschner
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232-9544, USA.
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11
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Abstract
OBJECTIVE In 2003, critical care and infectious disease experts representing 11 international organizations developed management guidelines for adjunctive therapies in sepsis that would be of practical use for the bedside clinician, under the auspices of the Surviving Sepsis Campaign, an international effort to increase awareness and to improve outcome in severe sepsis. DESIGN The process included a modified Delphi method, a consensus conference, several subsequent smaller meetings of subgroups and key individuals, teleconferences, and electronic-based discussion among subgroups and among the entire committee. METHODS The modified Delphi methodology used for grading recommendations built on a 2001 publication sponsored by the International Sepsis Forum. We undertook a systematic review of the literature graded along five levels to create recommendation grades from A to E, with A being the highest grade. Pediatric considerations to contrast adult and pediatric management are in the article by Parker et al. on p. S591. CONCLUSION Glycemic control (maintenance of glucose <150 mg/dL) is recommended. The beneficial effect of glycemic control appears to be related control of glucose and not the administration of insulin. Glycemic control should be combined with a nutritional protocol. The dialysis dose is important in sepsis-induced acute renal failure. Continuous hemofiltration offers easier management of fluid balance in hemodynamically unstable septic patients but in the absence of hemodynamic instability is equivalent to intermittent hemodialysis. It is uncertain whether high-volume hemofiltration improves prognosis in sepsis. Bicarbonate therapy is not recommended for the purpose of improving hemodynamics or reducing vasopressor requirements in the presence of lactic academia and pH >7.15.
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Affiliation(s)
- Alain Cariou
- Department of Intensive Care and Emergency Medicine, Cochin Hospital, University of Paris 5, Paris, France
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Gehlbach BK, Schmidt GA. Bench-to-bedside review: treating acid-base abnormalities in the intensive care unit - the role of buffers. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2004; 8:259-65. [PMID: 15312208 PMCID: PMC522834 DOI: 10.1186/cc2865] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The recognition and management of acid-base disorders is a commonplace activity for intensivists. Despite the frequency with which non-bicarbonate-losing forms of metabolic acidosis such as lactic acidosis occurs in critically ill patients, treatment is controversial. This article describes the properties of several buffering agents and reviews the evidence for their clinical efficacy. The evidence supporting and refuting attempts to correct arterial pH through the administration of currently available buffers is presented.
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Affiliation(s)
- Brian K Gehlbach
- Instructor of Medicine, Section of Pulmonary and Critical Care, University of Chicago, Chicago, Illinois, USA
| | - Gregory A Schmidt
- Professor of Medicine, Section of Pulmonary and Critical Care, University of Chicago, Chicago, Illinois, USA
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13
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Lipshultz SE, Somers MJG, Lipsitz SR, Colan SD, Jabs K, Rifai N. Serum cardiac troponin and subclinical cardiac status in pediatric chronic renal failure. Pediatrics 2003; 112:79-86. [PMID: 12837871 DOI: 10.1542/peds.112.1.79] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Patients with uremia often have elevated serum cardiac troponin T (cTnT) even without clinical heart damage. Pediatric patients are ideal for studies of the relationship between uremia and heart disease because they are unlikely to have cardiac risk factors other than uremia. OBJECTIVE To determine the relationship between uremia and cTnT levels. DESIGN Echocardiograms and blood chemistry results were obtained from 50 pediatric patients with chronic renal failure and without clinical heart disease. Levels of cTnT were tested for correlation with cardiac dysfunction. In multivariate analysis, biochemical aspects of renal disease and its treatment were tested for correlation with cardiac dysfunction. RESULTS Forty-nine patients had cardiovascular abnormalities, including increased left ventricular function and mass, elevated heart rate and blood pressure, and reduced LV afterload. LV contractility was inversely correlated with cTnT level (r = -0.36). Higher cTnT also correlated with higher serum creatine kinase-MB mass, lower serum parathyroid hormone, higher blood urea nitrogen and bicarbonate levels, and the use of diuretics, but not with higher cardiac troponin I. Left ventricular contractility was inversely related to serum creatinine, phosphorus, and the use of beta-blockers. CONCLUSIONS Elevated cTnT levels are not artifactual, but are genuine indicators of cardiomyocyte damage. Cardiac damage, indicated by either elevated cTnT or low LV contractility, is related to uremia, deranged calcium and phosphorus metabolism, and bicarbonate levels. Serum cTnT and LV contractility identify subclinical cardiac damage that could be treated to hopefully reduce cardiovascular morbidity and mortality in this high-risk population.
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Affiliation(s)
- Steven E Lipshultz
- Department of Cardiology, Children's Hospital, Boston, Massachusetts, USA.
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14
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Abstract
Severe acidemia (blood pH < 7.1 to 7.2) suppresses myocardial contractility, predisposes to cardiac arrhythmias, causes venoconstriction, and can decrease total peripheral vascular resistance and blood pressure, reduce hepatic blood flow, and impair oxygen delivery. These alterations in organ function can contribute to increased morbidity and mortality. Although it seemed logical to administer sodium bicarbonate to attenuate acidemia and therefore lessen the impact on cardiac function, the routine use of bicarbonate in the treatment of the most common causes of severe acidemia, diabetic ketoacidosis, lactic acidosis, and cardiac arrest, has been an issue of great controversy. Studies of animals and patients with these disorders have reported conflicting data on the benefits of bicarbonate, showing both beneficial and detrimental effects. Alternative alkalinizing agents, tris-hydroxymethyl aminomethane and Carbicarb, have shown some promise in studies of animals and humans, and reevaluation of these buffers in the treatment of severe acidemic states seems warranted. The potential value of base therapy in the treatment of severe acidemia remains an important issue, and further studies are required to determine which patients should be administered base therapy and what base should be used.
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Affiliation(s)
- J A Kraut
- Division of Nephrology, Veterans Administration Greater Los Angeles Health Care System, Los Angeles, CA 90073, USA.
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15
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Weber T, Tschernich H, Sitzwohl C, Ullrich R, Germann P, Zimpfer M, Sladen RN, Huemer G. Tromethamine buffer modifies the depressant effect of permissive hypercapnia on myocardial contractility in patients with acute respiratory distress syndrome. Am J Respir Crit Care Med 2000; 162:1361-5. [PMID: 11029345 DOI: 10.1164/ajrccm.162.4.9808092] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
In patients with acute respiratory distress syndrome (ARDS), permissive hypercapnia is a strategy to decrease airway pressures to prevent ventilator-induced lung damage by lowering tidal volumes and tolerating higher arterial carbon dioxide tension. However, in experimental studies hypercapnia impairs myocardial contractility and hemodynamic function. We investigated the effect of short-term permissive hypercapnia on myocardial contractility and hemodynamics in patients with ARDS. We hypothesized that the administration of tromethamine (THAM), a buffer which does not increase carbon dioxide production, would modify these changes. In 12 patients with ARDS, permissive hypercapnia was implemented for 2 h with a target Pa(CO(2))of 80 mm Hg. Patients were randomized to have respiratory acidosis corrected by THAM (pH-corrected group), or not corrected (pH-uncorrected group). Hemodynamic responses were measured, and transesophageal echocardiography (TEE) was used to determine myocardial contractility. Permissive hypercapnia resulted in significant decreases in systemic vascular resistance (SVR) and increases in cardiac output (Q). Myocardial contractility decreased in both groups but significantly less in the pH-corrected group (approximately 10%) than in the pH-uncorrected group (approximately 18%, p < 0.05). Mean arterial pressure decreased and mean pulmonary arterial pressure increased significantly only in the pH-uncorrected group. All values returned to baseline conditions 1 h after permissive hypercapnia was terminated. Our study demonstrates a reversible depression of myocardial contractility and hemodynamic alterations during rapid permissive hypercapnia which were attenuated by buffering with THAM. This may have applicability to the clinical strategy of permissive hypercapnia and allow the benefit of decreased airway pressures to be realized while minimizing the adverse hemodynamic effects of hypercapnic acidosis.
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Affiliation(s)
- T Weber
- Department of Anesthesiology and General Intensive Care, University of Vienna, Austria
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16
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Kallet RH, Jasmer RM, Luce JM, Lin LH, Marks JD. The treatment of acidosis in acute lung injury with tris-hydroxymethyl aminomethane (THAM). Am J Respir Crit Care Med 2000; 161:1149-53. [PMID: 10764304 DOI: 10.1164/ajrccm.161.4.9906031] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Mechanical hyperventilation of acidemic patients with acute lung injury (ALI) requires the use of high volumes and pressures that may worsen lung injury. However, permissive hypercapnia in the presence of shock, metabolic acidosis, and multi-organ system dysfunction may compromise normal cellular function. Tris-hydroxymethyl aminomethane (THAM) may be an effective method to control acidosis in this circumstance. Protonated THAM is excreted by the kidneys, so that carbon dioxide production is not raised. In an uncontrolled study, we administered THAM to 10 patients with acidosis (mean pH = 7.14) and ALI (mean lung injury score = 3.28) in whom adequate control of arterial pH could not be maintained during either eucapnic ventilation or permissive hypercapnia ventilation. THAM was given at a mean dose of 0.55 mmol/kg/h. Administration of THAM was associated with significant improvements in arterial pH and base deficit, and a decrease in arterial carbon dioxide tension that could not be fully accounted for by ventilation. Although further studies are needed to confirm these observations, THAM appears to be an effective alternative to sodium bicarbonate for treating acidosis during ALI.
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Affiliation(s)
- R H Kallet
- Department of Anesthesia and Division of Pulmonary and Critical Care Medicine, University of California, San Francisco at San Francisco General Hospital, San Francisco, California 94110, USA.
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17
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Abstract
Lactic acidosis often challenges the intensivist and is associated with a strikingly high mortality. Treatment involves discerning and correcting its underlying cause, ensuring adequate oxygen delivery to tissues, reducing oxygen demand through sedation and mechanical ventilation, and (most controversially) attempting to alkalinize the blood with IV sodium bicarbonate. Here we review the literature to answer the following questions: Is a low pH bad? Can sodium bicarbonate raise the pH in vivo? Does increasing the blood pH with sodium bicarbonate have any salutary effects? Does sodium bicarbonate have negative side effects? We find that the oft-cited rationale for bicarbonate use, that it might ameliorate the hemodynamic depression of metabolic acidemia, has been disproved convincingly. Further, given the lack of evidence supporting its use, we cannot condone bicarbonate administration for patients with lactic acidosis, regardless of the degree of acidemia.
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Affiliation(s)
- S M Forsythe
- Department of Medicine, University of Chicago School of Medicine, Chicago, IL, USA
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18
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Does aprotinin modify the effects of ischaemia-reperfusion on the myocardial performance of a blood perfused isolated rabbit heart? Eur J Anaesthesiol 1999. [DOI: 10.1097/00003643-199910000-00010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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20
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Nahas GG, Sutin KM, Fermon C, Streat S, Wiklund L, Wahlander S, Yellin P, Brasch H, Kanchuger M, Capan L, Manne J, Helwig H, Gaab M, Pfenninger E, Wetterberg T, Holmdahl M, Turndorf H. Guidelines for the treatment of acidaemia with THAM. Drugs 1998; 55:191-224. [PMID: 9506241 DOI: 10.2165/00003495-199855020-00003] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
THAM (trometamol; tris-hydroxymethyl aminomethane) is a biologically inert amino alcohol of low toxicity, which buffers carbon dioxide and acids in vitro and in vivo. At 37 degrees C, the pK (the pH at which the weak conjugate acid or base in the solution is 50% ionised) of THAM is 7.8, making it a more effective buffer than bicarbonate in the physiological range of blood pH. THAM is a proton acceptor with a stoichiometric equivalence of titrating 1 proton per molecule. In vivo, THAM supplements the buffering capacity of the blood bicarbonate system, accepting a proton, generating bicarbonate and decreasing the partial pressure of carbon dioxide in arterial blood (paCO2). It rapidly distributes through the extracellular space and slowly penetrates the intracellular space, except for erythrocytes and hepatocytes, and it is excreted by the kidney in its protonated form at a rate that slightly exceeds creatinine clearance. Unlike bicarbonate, which requires an open system for carbon dioxide elimination in order to exert its buffering effect, THAM is effective in a closed or semiclosed system, and maintains its buffering power in the presence of hypothermia. THAM rapidly restores pH and acid-base regulation in acidaemia caused by carbon dioxide retention or metabolic acid accumulation, which have the potential to impair organ function. Tissue irritation and venous thrombosis at the site of administration occurs with THAM base (pH 10.4) administered through a peripheral or umbilical vein: THAM acetate 0.3 mol/L (pH 8.6) is well tolerated, does not cause tissue or venous irritation and is the only formulation available in the US. In large doses, THAM may induce respiratory depression and hypoglycaemia, which will require ventilatory assistance and glucose administration. The initial loading dose of THAM acetate 0.3 mol/L in the treatment of acidaemia may be estimated as follows: THAM (ml of 0.3 mol/L solution) = lean body-weight (kg) x base deficit (mmol/L). The maximum daily dose is 15 mmol/kg for an adult (3.5L of a 0.3 mol/L solution in a 70kg patient). When disturbances result in severe hypercapnic or metabolic acidaemia, which overwhelms the capacity of normal pH homeostatic mechanisms (pH < or = 7.20), the use of THAM within a 'therapeutic window' is an effective therapy. It may restore the pH of the internal milieu, thus permitting the homeostatic mechanisms of acid-base regulation to assume their normal function. In the treatment of respiratory failure, THAM has been used in conjunction with hypothermia and controlled hypercapnia. Other indications are diabetic or renal acidosis, salicylate or barbiturate intoxication, and increased intracranial pressure associated with cerebral trauma. THAM is also used in cardioplegic solutions, during liver transplantation and for chemolysis of renal calculi. THAM administration must follow established guidelines, along with concurrent monitoring of acid-base status (blood gas analysis), ventilation, and plasma electrolytes and glucose.
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Affiliation(s)
- G G Nahas
- Department of Anaesthesiology, New York University Medical Center, New York, USA.
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