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Tiruvoipati R, Serpa Neto A, Young M, Marhoon N, Wilson J, Gupta S, Pilcher D, Bailey M, Bellomo R. An Exploratory Analysis of the Association between Hypercapnia and Hospital Mortality in Critically Ill Patients with Sepsis. Ann Am Thorac Soc 2022; 19:245-254. [PMID: 34380007 DOI: 10.1513/annalsats.202102-104oc] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Rationale: Hypercapnia may affect the outcome of sepsis. Very few clinical studies conducted in noncritically ill patients have investigated the effects of hypercapnia and hypercapnic acidemia in the context of sepsis. The effect of hypercapnia in critically ill patients with sepsis remains inadequately studied. Objectives: To investigate the association of hypercapnia with hospital mortality in critically ill patients with sepsis. Methods: This is a retrospective study conducted in three tertiary public hospitals. Critically ill patients with sepsis from three intensive care units between January 2011 and May 2019 were included. Five cohorts (exposure of at least 24, 48, 72, 120, and 168 hours) were created to account for immortal time bias and informative censoring. The association between hypercapnia exposure and hospital mortality was assessed with multivariable models. Subgroup analyses compared ventilated versus nonventilated and pulmonary versus nonpulmonary sepsis patients. Results: We analyzed 84,819 arterial carbon dioxide pressure measurements in 3,153 patients (57.6% male; median age was 62.5 years). After adjustment for key confounders, both in mechanically ventilated and nonventilated patients and in patients with pulmonary or nonpulmonary sepsis, there was no independent association of hypercapnia with hospital mortality. In contrast, in ventilated patients, the presence of prolonged exposure to both hypercapnia and acidemia was associated with increased mortality (highest odds ratio of 16.5 for ⩾120 hours of potential exposure; P = 0.007). Conclusions: After adjustment, isolated hypercapnia was not associated with increased mortality in patients with sepsis, whereas prolonged hypercapnic acidemia was associated with increased risk of mortality. These hypothesis-generating observations suggest that as hypercapnia is not an independent risk factor for mortality, trials of permissive hypercapnia avoiding or minimizing acidemia in sepsis may be safe.
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Affiliation(s)
- Ravindranath Tiruvoipati
- Department of Intensive Care Medicine, Peninsula Health, Melbourne, Victoria, Australia
- Australian and New Zealand Intensive Care Research Centre, Peninsula Clinical School, School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
| | - Ary Serpa Neto
- Australian and New Zealand Intensive Care Research Centre, Peninsula Clinical School, School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
| | - Marcus Young
- Department of Intensive Care, Austin Health, Heidelberg, Victoria, Australia
| | - Nada Marhoon
- Department of Intensive Care, Austin Health, Heidelberg, Victoria, Australia
| | - John Wilson
- Peninsula Health Informatics, Frankston Hospital, Melbourne, Victoria, Australia
| | - Sachin Gupta
- Department of Intensive Care Medicine, Peninsula Health, Melbourne, Victoria, Australia
- Australian and New Zealand Intensive Care Research Centre, Peninsula Clinical School, School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
| | - David Pilcher
- Australian and New Zealand Intensive Care Research Centre, Peninsula Clinical School, School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
- Department of Intensive Care Medicine, The Alfred Hospital, Melbourne, Victoria, Australia; and
| | - Michael Bailey
- Australian and New Zealand Intensive Care Research Centre, Peninsula Clinical School, School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
- Data Analytics Research and Evaluation, the University of Melbourne and Austin Hospital, Melbourne, Victoria, Australia
| | - Rinaldo Bellomo
- Australian and New Zealand Intensive Care Research Centre, Peninsula Clinical School, School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
- Department of Intensive Care, Austin Health, Heidelberg, Victoria, Australia
- Data Analytics Research and Evaluation, the University of Melbourne and Austin Hospital, Melbourne, Victoria, Australia
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Phelan DE, Mota C, Lai C, Kierans SJ, Cummins EP. Carbon dioxide-dependent signal transduction in mammalian systems. Interface Focus 2021; 11:20200033. [PMID: 33633832 PMCID: PMC7898142 DOI: 10.1098/rsfs.2020.0033] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2020] [Indexed: 12/15/2022] Open
Abstract
Carbon dioxide (CO2) is a fundamental physiological gas known to profoundly influence the behaviour and health of millions of species within the plant and animal kingdoms in particular. A recent Royal Society meeting on the topic of 'Carbon dioxide detection in biological systems' was extremely revealing in terms of the multitude of roles that different levels of CO2 play in influencing plants and animals alike. While outstanding research has been performed by leading researchers in the area of plant biology, neuronal sensing, cell signalling, gas transport, inflammation, lung function and clinical medicine, there is still much to be learned about CO2-dependent sensing and signalling. Notably, while several key signal transduction pathways and nodes of activity have been identified in plants and animals respectively, the precise wiring and sensitivity of these pathways to CO2 remains to be fully elucidated. In this article, we will give an overview of the literature relating to CO2-dependent signal transduction in mammalian systems. We will highlight the main signal transduction hubs through which CO2-dependent signalling is elicited with a view to better understanding the complex physiological response to CO2 in mammalian systems. The main topics of discussion in this article relate to how changes in CO2 influence cellular function through modulation of signal transduction networks influenced by pH, mitochondrial function, adenylate cyclase, calcium, transcriptional regulators, the adenosine monophosphate-activated protein kinase pathway and direct CO2-dependent protein modifications. While each of these topics will be discussed independently, there is evidence of significant cross-talk between these signal transduction pathways as they respond to changes in CO2. In considering these core hubs of CO2-dependent signal transduction, we hope to delineate common elements and identify areas in which future research could be best directed.
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Affiliation(s)
- D. E. Phelan
- School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - C. Mota
- School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - C. Lai
- School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - S. J. Kierans
- School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - E. P. Cummins
- School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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Masterson C, Horie S, McCarthy SD, Gonzalez H, Byrnes D, Brady J, Fandiño J, Laffey JG, O'Toole D. Hypercapnia in the critically ill: insights from the bench to the bedside. Interface Focus 2021; 11:20200032. [PMID: 33628425 PMCID: PMC7898152 DOI: 10.1098/rsfs.2020.0032] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2020] [Indexed: 01/16/2023] Open
Abstract
Carbon dioxide (CO2) has long been considered, at best, a waste by-product of metabolism, and at worst, a toxic molecule with serious health consequences if physiological concentration is dysregulated. However, clinical observations have revealed that 'permissive' hypercapnia, the deliberate allowance of respiratory produced CO2 to remain in the patient, can have anti-inflammatory effects that may be beneficial in certain circumstances. In parallel, studies at the cell level have demonstrated the profound effect of CO2 on multiple diverse signalling pathways, be it the effect from CO2 itself specifically or from the associated acidosis it generates. At the whole organism level, it now appears likely that there are many biological sensing systems designed to respond to CO2 concentration and tailor respiratory and other responses to atmospheric or local levels. Animal models have been widely employed to study the changes in CO2 levels in various disease states and also to what extent permissive or even directly delivered CO2 can affect patient outcome. These findings have been advanced to the bedside at the same time that further clinical observations have been elucidated at the cell and animal level. Here we present a synopsis of the current understanding of how CO2 affects mammalian biological systems, with a particular emphasis on inflammatory pathways and diseases such as lung specific or systemic sepsis. We also explore some future directions and possibilities, such as direct control of blood CO2 levels, that could lead to improved clinical care in the future.
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Jerkic M, Litvack ML, Gagnon S, Otulakowski G, Zhang H, Rotstein O, Kavanagh BP, Post M, Laffey JG. Embryonic-Derived Myb- Macrophages Enhance Bacterial Clearance and Improve Survival in Rat Sepsis. Int J Mol Sci 2021; 22:ijms22063190. [PMID: 33804806 PMCID: PMC8004006 DOI: 10.3390/ijms22063190] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/15/2021] [Accepted: 03/17/2021] [Indexed: 12/13/2022] Open
Abstract
Peritoneal resident macrophages play a key role in combating sepsis in the peritoneal cavity. We sought to determine if peritoneal transplantation of embryonic Myb- "peritoneal-like" macrophages attenuate abdominal fecal sepsis. Directed differentiation of rodent pluripotent stem cells (PSCs) was used in factor-defined media to produce embryonic-derived large "peritoneal-like" macrophages (Ed-LPM) that expressed peritoneal macrophage markers and demonstrated phagocytic capacity. Preclinical in vivo studies determined Ed-LPM efficacy in rodent abdominal fecal sepsis with or without Meropenem. Ex vivo studies explored the mechanism and effects of Ed-LPM on host immune cell number and function, including phagocytosis, reactive oxygen species (ROS) production, efferocytosis and apoptosis. Ed-LPM reduced sepsis severity by decreasing bacterial load in the liver, spleen and lungs. Ed-LPM therapy significantly improved animal survival by ~30% and reduced systemic bacterial burden to levels comparable to Meropenem therapy. Ed-LPM therapy decreased peritoneal TNFα while increasing IL-10 concentrations. Ed-LPMs enhanced peritoneal macrophage phagocytosis of bacteria, increased macrophage production of ROS and restored homeostasis via apoptosis and efferocytosis-induced clearance of neutrophils. In conclusion, Ed-LPM reduced systemic sepsis severity, improved survival and reduced bacterial load by enhancing peritoneal macrophage bacterial phagocytosis and killing and clearance of intra-peritoneal neutrophils. Macrophage therapy may be a potential strategy to address sepsis.
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Affiliation(s)
- Mirjana Jerkic
- Keenan Research Centre for Biomedical Science, Unity Health Toronto St. Michael’s, University of Toronto, Toronto, ON M5B 1T8, Canada; (M.J.); (S.G.); (H.Z.); (O.R.)
| | - Michael L. Litvack
- Translational Medicine Program, Hospital for Sick Children, University of Toronto, Toronto, ON M5G 0A4, Canada; (M.L.L.); (G.O.); (B.P.K.); (M.P.)
| | - Stéphane Gagnon
- Keenan Research Centre for Biomedical Science, Unity Health Toronto St. Michael’s, University of Toronto, Toronto, ON M5B 1T8, Canada; (M.J.); (S.G.); (H.Z.); (O.R.)
| | - Gail Otulakowski
- Translational Medicine Program, Hospital for Sick Children, University of Toronto, Toronto, ON M5G 0A4, Canada; (M.L.L.); (G.O.); (B.P.K.); (M.P.)
| | - Haibo Zhang
- Keenan Research Centre for Biomedical Science, Unity Health Toronto St. Michael’s, University of Toronto, Toronto, ON M5B 1T8, Canada; (M.J.); (S.G.); (H.Z.); (O.R.)
| | - Ori Rotstein
- Keenan Research Centre for Biomedical Science, Unity Health Toronto St. Michael’s, University of Toronto, Toronto, ON M5B 1T8, Canada; (M.J.); (S.G.); (H.Z.); (O.R.)
| | - Brian P. Kavanagh
- Translational Medicine Program, Hospital for Sick Children, University of Toronto, Toronto, ON M5G 0A4, Canada; (M.L.L.); (G.O.); (B.P.K.); (M.P.)
- Department of Critical Care Medicine, Hospital for Sick Children, University of Toronto, Toronto, ON M5G 1X8, Canada
- Departments of Anesthesia, Physiology and Interdepartmental Division of Critical Care, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Martin Post
- Translational Medicine Program, Hospital for Sick Children, University of Toronto, Toronto, ON M5G 0A4, Canada; (M.L.L.); (G.O.); (B.P.K.); (M.P.)
- Departments of Anesthesia, Physiology and Interdepartmental Division of Critical Care, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - John G. Laffey
- Keenan Research Centre for Biomedical Science, Unity Health Toronto St. Michael’s, University of Toronto, Toronto, ON M5B 1T8, Canada; (M.J.); (S.G.); (H.Z.); (O.R.)
- Departments of Anesthesia, Physiology and Interdepartmental Division of Critical Care, University of Toronto, Toronto, ON M5S 1A1, Canada
- Department of Anesthesia and Critical Care Medicine, Unity Health Toronto St. Michael’s, Toronto, ON M5B 1W8, Canada
- Regenerative Medicine Institute (REMEDI) at CÚRAM Centre for Research in Medical Devices, Biomedical Sciences Building, School of Medicine, National University of Ireland Galway, H91 TK33 Galway, Ireland
- Correspondence: ; Tel.: +1-353-91-495662
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Chand R, Swenson ER, Goldfarb DS. Sodium bicarbonate therapy for acute respiratory acidosis. Curr Opin Nephrol Hypertens 2021; 30:223-230. [PMID: 33395037 DOI: 10.1097/mnh.0000000000000687] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
PURPOSE OF REVIEW Respiratory acidosis is commonly present in patients with respiratory failure. The usual treatment of hypercapnia is to increase ventilation. During the recent surge of COVID-19, respiratory acidosis unresponsive to increased mechanical ventilatory support was common. Increasing mechanical ventilation comes at the expense of barotrauma and hemodynamic compromise from increasing positive end-expiratory pressures or minute ventilation. Treating acute respiratory acidemia with sodium bicarbonate remains controversial. RECENT FINDINGS There are no randomized controlled trials of administration of sodium bicarbonate for respiratory acidemia. A recent review concluded that alkali therapy for mixed respiratory and metabolic acidosis might be useful but was based on the conflicting and not conclusive literature regarding metabolic acidosis. This strategy should not be extrapolated to treatment of respiratory acidemia. Low tidal volume ventilation in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) has beneficial effects associated with permissive hypercapnia. Whether the putative benefits will be negated by administration of alkali is not known. Hypercapnic acidosis is well tolerated, with few adverse effects as long as tissue perfusion and oxygenation are maintained. SUMMARY There is a lack of clinical evidence that administration of sodium bicarbonate for respiratory acidosis has a net benefit; in fact, there are potential risks associated with it.
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Affiliation(s)
- Ranjeeta Chand
- Nephrology Division, New York University Langone Health and Nephrology Section, NY Harbor VA Healthcare System
| | - Erik R Swenson
- Pulmonary, Critical Care and Sleep Medicine Division, University of Washington, and VA Puget Sound Healthcare System, Seattle, Washington, USA
| | - David S Goldfarb
- Nephrology Division, New York University Langone Health and Nephrology Section, NY Harbor VA Healthcare System
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Human Umbilical Cord Mesenchymal Stromal Cells Attenuate Systemic Sepsis in Part by Enhancing Peritoneal Macrophage Bacterial Killing via Heme Oxygenase-1 Induction in Rats. Anesthesiology 2020; 132:140-154. [PMID: 31764154 DOI: 10.1097/aln.0000000000003018] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Mesenchymal stromal cells have therapeutic potential in sepsis, but the mechanism of action is unclear. We tested the effects, dose-response, and mechanisms of action of cryopreserved, xenogeneic-free human umbilical cord mesenchymal stromal cells in a rat model of fecal peritonitis, and examined the role of heme oxygenase-1 in protection. METHODS Separate in vivo experiments evaluated mesenchymal stromal cells in fecal sepsis, established dose response (2, 5, and 10 million cells/kg), and the role of heme oxygenase-1 in mediating human umbilical cord-derived mesenchymal stromal/stem cell effects. Ex vivo studies utilized pharmacologic blockers and small inhibitory RNAs to evaluate mechanisms of mesenchymal stromal cell enhanced function in (rodent, healthy and septic human) macrophages. RESULTS Human umbilical cord mesenchymal stromal cells reduced injury and increased survival (from 48%, 12 of 25 to 88%, 14 of 16, P = 0.0033) in fecal sepsis, with dose response studies demonstrating that 10 million cells/kg was the most effective dose. Mesenchymal stromal cells reduced bacterial load and peritoneal leukocyte infiltration (from 9.9 ± 3.1 × 10/ml to 6.2 ± 1.8 × 10/ml, N = 8 to 10 per group, P < 0.0001), and increased heme oxygenase-1 expression in peritoneal macrophages, liver, and spleen. Heme oxygenase-1 blockade abolished the effects of mesenchymal stromal cells (N = 7 or 8 per group). Mesenchymal stromal cells also increased heme oxygenase-1 expression in macrophages from healthy donors and septic patients. Direct ex vivo upregulation of macrophage heme oxygenase-1 enhanced macrophage function (phagocytosis, reactive oxygen species production, bacterial killing). Blockade of lipoxin A4 production in mesenchymal stromal cells, and of prostaglandin E2 synthesis in mesenchymal stromal cell/macrophage cocultures, prevented upregulation of heme oxygenase-1 in macrophages (from 9.6 ± 5.5-fold to 2.3 ± 1.3 and 2.4 ± 2.3 respectively, P = 0.004). Knockdown of heme oxygenase-1 production in macrophages ablated mesenchymal stromal cell enhancement of macrophage phagocytosis. CONCLUSIONS Human umbilical cord mesenchymal stromal cells attenuate systemic sepsis by enhancing peritoneal macrophage bacterial killing, mediated partly via upregulation of peritoneal macrophage heme oxygenase-1. Lipoxin A4 and prostaglandin E2 play key roles in the mesenchymal stromal cell and macrophage interaction.
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Lu Z, Casalino-Matsuda SM, Nair A, Buchbinder A, Budinger GRS, Sporn PHS, Gates KL. A role for heat shock factor 1 in hypercapnia-induced inhibition of inflammatory cytokine expression. FASEB J 2018; 32:3614-3622. [PMID: 29405096 DOI: 10.1096/fj.201701164r] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Hypercapnia, elevated levels of CO2 in the blood, is a known marker for poor clinical prognosis and is associated with increased mortality in patients hospitalized with both bacterial and viral pneumonias. Although studies have established a connection between elevated CO2 levels and poor pneumonia outcomes, a mechanistic basis of this association has not yet been established. We previously reported that hypercapnia inhibits expression of key NF-κB-regulated, innate immune cytokines, TNF-α, and IL-6, in LPS-stimulated macrophages in vitro and in mice during Pseudomonas pneumonia. The transcription factor heat shock factor 1 (HSF1) is important in maintaining proteostasis during stress and has been shown to negatively regulate NF-κB activity. In this study, we tested the hypothesis that HSF1 activation in response to hypercapnia results in attenuated NF-κB-regulated gene expression. We found that hypercapnia induced the protein expression and nuclear accumulation of HSF1 in primary murine alveolar macrophages and in an alveolar macrophage cell line (MH-S). In MH-S cells treated with short interfering RNA targeting Hsf1, LPS-induced IL-6 and TNF-α release were elevated during exposure to hypercapnia. Pseudomonas-infected Hsf1+/+ (wild-type) mice, maintained in a hypercapnic environment, showed lower levels of IL-6 and TNF-α in bronchoalveolar lavage fluid and IL-1β in lung tissue than did infected mice maintained in room air. In contrast, infected Hsf1+/- mice exposed to either hypercapnia or room air had similarly elevated levels of those cytokines. These results suggest that hypercapnia-mediated inhibition of NF-κB cytokine production is dependent on HSF1 expression and/or activation.-Lu, Z., Casalino-Matsuda, S. M., Nair, A., Buchbinder, A., Budinger, G. R. S., Sporn, P. H. S., Gates, K. L. A role for heat shock factor 1 in hypercapnia-induced inhibition of inflammatory cytokine expression.
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Affiliation(s)
- Ziyan Lu
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - S Marina Casalino-Matsuda
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Aisha Nair
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.,Jesse Brown Veteran Affairs Medical Center, Chicago, Illinois, USA
| | - Anja Buchbinder
- Universities of Giessen and Marburg Lung Center, Giessen, Germany
| | - G R Scott Budinger
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.,Jesse Brown Veteran Affairs Medical Center, Chicago, Illinois, USA
| | - Peter H S Sporn
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.,Jesse Brown Veteran Affairs Medical Center, Chicago, Illinois, USA
| | - Khalilah L Gates
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
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Barnes T, Zochios V, Parhar K. Re-examining Permissive Hypercapnia in ARDS: A Narrative Review. Chest 2017; 154:185-195. [PMID: 29175086 DOI: 10.1016/j.chest.2017.11.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 10/20/2017] [Accepted: 11/13/2017] [Indexed: 12/16/2022] Open
Abstract
Lung-protective ventilation (LPV) has become the cornerstone of management in patients with ARDS. A subset of patients is unable to tolerate LPV without significant CO2 elevation. In these patients, permissive hypercapnia is used. Although thought to be benign, it is becoming increasingly evident that elevated CO2 levels have significant physiological effects. In this narrative review, we highlight clinically relevant end-organ effects in both animal models and clinical studies. We also explore the association between elevated CO2, acute cor pulmonale, and ICU mortality. We conclude with a brief review of alternative therapies for CO2 management currently under investigation in patients with moderate to severe ARDS.
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Affiliation(s)
- Tavish Barnes
- Department of Critical Care Medicine, University of Calgary, Calgary, AB, Canada
| | - Vasileios Zochios
- Department of Critical Care Medicine, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital, College of Medical and Dental Sciences, University of Birmingham, Birmingham, England
| | - Ken Parhar
- Department of Critical Care Medicine, University of Calgary, Calgary, AB, Canada.
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Fuchs H, Rossmann N, Schmid MB, Hoenig M, Thome U, Mayer B, Klotz D, Hummler HD. Permissive hypercapnia for severe acute respiratory distress syndrome in immunocompromised children: A single center experience. PLoS One 2017. [PMID: 28632754 PMCID: PMC5478142 DOI: 10.1371/journal.pone.0179974] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Controlled hypoventilation while accepting hypercapnia has been advocated to reduce ventilator-induced lung injury. The aim of the study was to analyze outcomes of a cohort of immunocompromised children with acute respiratory distress syndrome (ARDS) ventilated with a strategy of stepwise increasing PCO2 targets up to 140 mm Hg. METHODS Retrospective analysis of outcomes of a cohort of children with oncologic disease or after stem cell transplantation and severe respiratory failure in comparison with a historical control cohort. RESULTS Out of 150 episodes of admission to the PICU 88 children underwent invasive mechanical ventilation for >24h (overall survival 75%). In a subgroup of 38 children with high ventilator requirements the PCO2 target ranges were increased stepwise. Fifteen children survived and were discharged from the PICU. Severe pulmonary hypertension was seen in two patients and no case of cerebral edema was observed. Long term outcome was available in 15 patients and 10 of these patients survived without adverse neurological sequelae. With introduction of this strategy survival of immunocompromised children undergoing mechanical ventilation for >24h increased to 48% compared to 32% prior to introduction (historical cohort). CONCLUSIONS A ventilation strategy incorporating very high carbon dioxide levels to allow for low tidal volumes and limited inspiratory pressures is feasible in children. Even severe hypercapnia may be well tolerated. No severe side effects associated with hypercapnia were observed. This strategy could potentially increase survival in immunocompromised children with severe ARDS.
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Affiliation(s)
- Hans Fuchs
- Center for Pediatrics, Department of Neonatology and Pediatric Intensive Care, Medical Center – Albert Ludwig University of Freiburg, Faculty of Medicine, Freiburg, Germany
- * E-mail:
| | - Nicola Rossmann
- Division of Neonatology and Pediatric Critical Care, Department for Pediatrics and Adolescent Medicine, Ulm University, Ulm, Germany
| | - Manuel B. Schmid
- Department of Neonatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Manfred Hoenig
- Oncology and stem cell transplantation, Department for Pediatrics and Adolescent Medicine, Ulm University, Ulm, Germany
| | - Ulrich Thome
- Division of Neonatology, University Hospital of Leipzig, Leipzig, Germany
| | - Benjamin Mayer
- Institute of Epidemiology and Medical Biometry, Ulm University, Ulm, Germany
| | - Daniel Klotz
- Center for Pediatrics, Department of Neonatology and Pediatric Intensive Care, Medical Center – Albert Ludwig University of Freiburg, Faculty of Medicine, Freiburg, Germany
| | - Helmut D. Hummler
- Division of Neonatology and Pediatric Critical Care, Department for Pediatrics and Adolescent Medicine, Ulm University, Ulm, Germany
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Zochios V, Parhar K, Tunnicliffe W, Roscoe A, Gao F. The Right Ventricle in ARDS. Chest 2017; 152:181-193. [PMID: 28267435 DOI: 10.1016/j.chest.2017.02.019] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 02/15/2017] [Accepted: 02/17/2017] [Indexed: 02/08/2023] Open
Abstract
ARDS is associated with poor clinical outcomes, with a pooled mortality rate of approximately 40% despite best standards of care. Current therapeutic strategies are based on improving oxygenation and pulmonary compliance while minimizing ventilator-induced lung injury. It has been demonstrated that relative hypoxemia can be well tolerated, and improvements in oxygenation do not necessarily translate into survival benefit. Cardiac failure, in particular right ventricular dysfunction (RVD), is commonly encountered in moderate to severe ARDS and is reported to be one of the major determinants of mortality. The prevalence rate of echocardiographically evident RVD in ARDS varies across studies, ranging from 22% to 50%. Although there is no definitive causal relationship between RVD and mortality, severe RVD is associated with increased mortality. Factors that can adversely affect RV function include hypoxic pulmonary vasoconstriction, hypercapnia, and invasive ventilation with high driving pressure. It might be expected that early diagnosis of RVD would be of benefit; however, echocardiographic markers (qualitative and quantitative) used to prospectively evaluate the right ventricle in ARDS have not been tested in adequately powered studies. In this review, we examine the prognostic implications and pathophysiology of RVD in ARDS and discuss available diagnostic modalities and treatment options. We aim to identify gaps in knowledge and directions for future research that could potentially improve clinical outcomes in this patient population.
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Affiliation(s)
- Vasileios Zochios
- Department of Critical Care Medicine, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital, Edgbaston; Institute of Inflammation and Ageing, Centre of Translational Inflammation Research, University of Birmingham, Birmingham.
| | - Ken Parhar
- Department of Critical Care Medicine, the University of Calgary, Calgary, AB, Canada
| | - William Tunnicliffe
- Department of Critical Care Medicine, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital, Edgbaston
| | - Andrew Roscoe
- Department of Cardiothoracic Anesthesia and Critical Care Medicine, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge
| | - Fang Gao
- Institute of Inflammation and Ageing, Centre of Translational Inflammation Research, University of Birmingham, Birmingham; Academic Department of Anesthesia, Critical Care, Pain and Resuscitation, Heart of England NHS Foundation Trust, Birmingham, England, and The 2nd Affiliated Hospital and Yuying Children's Hospital Wenzhou Medical University, Wenzhou, China
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11
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Morelli A, Del Sorbo L, Pesenti A, Ranieri VM, Fan E. Extracorporeal carbon dioxide removal (ECCO 2R) in patients with acute respiratory failure. Intensive Care Med 2017; 43:519-530. [PMID: 28132075 DOI: 10.1007/s00134-016-4673-0] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 12/29/2016] [Indexed: 12/14/2022]
Abstract
PURPOSE To review the available knowledge related to the use of ECCO2R as adjuvant strategy to mechanical ventilation (MV) in various clinical settings of acute respiratory failure (ARF). METHODS Expert opinion and review of the literature. RESULTS ECCO2R may be a promising adjuvant therapeutic strategy for the management of patients with severe exacerbations of COPD and for the achievement of protective or ultra-protective ventilation in patients with ARDS without life-threatening hypoxemia. Given the observational nature of most of the available clinical data and differences in technical features and performances of current devices, the balance of risks and benefits for or against ECCO2R in such patient populations remains unclear CONCLUSIONS: ECCO2R is currently an experimental technique rather than an accepted therapeutic strategy in ARF-its safety and efficacy require confirmation in clinical trials.
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Affiliation(s)
- Andrea Morelli
- Department of Anesthesiology and Intensive Care, Policlinico Umberto 1, Sapienza University of Rome, Rome, Italy
| | - Lorenzo Del Sorbo
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada.,Extracorporeal Life Support Program, Toronto General Hospital, 585 University Avenue, PMB 11-123, Toronto, ON, M5G 2N2, Canada
| | - Antonio Pesenti
- Fondazione IRCCS Ca' Granda, Ospendale Maggiore Policlinico and Department of Pathophysiology and Transplantation, Universita degli Studi di Milano, Milan, Italy
| | - V Marco Ranieri
- Department of Anesthesiology and Intensive Care, Policlinico Umberto 1, Sapienza University of Rome, Rome, Italy
| | - Eddy Fan
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada. .,Extracorporeal Life Support Program, Toronto General Hospital, 585 University Avenue, PMB 11-123, Toronto, ON, M5G 2N2, Canada.
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12
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Schneberger D, Cloonan D, DeVasure JM, Bailey KL, Romberger DJ, Wyatt TA. Effect of elevated carbon dioxide on bronchial epithelial innate immune receptor response to organic dust from swine confinement barns. Int Immunopharmacol 2015; 27:76-84. [PMID: 25921030 PMCID: PMC4465527 DOI: 10.1016/j.intimp.2015.04.031] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 03/27/2015] [Accepted: 04/14/2015] [Indexed: 01/25/2023]
Abstract
Hypercapnia is known to have immunoregulatory effects within the lung. Cell culture systems demonstrate this in both macrophages and alveolar cell lines, suggesting that the alveoli are affected by changes in CO2 levels. We hypothesized that hypercapnia would also modulate human bronchial epithelial cell immune responses. Innate immune responses to Pam3CSK4 (TLR2 ligand), LPS (TLR4 ligand) and a complex innate immune stimulus, an extract from the organic dust of swine confinement barns (barn dust extract or BDE), were tested in a human bronchial epithelial cell line, BEAS-2B. Both TLR ligands showed a decrease in IL-6 and IL-8 production, and an increase in MCP-1 in response to elevated CO2 indicating an enhancement in cytokine production to hypercapnia. This change was not reflected in expression levels of TLR receptor RNA which remained unchanged in response to elevated CO2. Interestingly, barn dust showed an increase in IL-6, IL-8 and MCP-1 response at 9% CO2, suggesting that elevated CO2 exerts different effects on different stimuli. Our results show that airway epithelial cell immune responses to barn dust respond differently to hypercapnic conditions than individual TLR ligands.
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Affiliation(s)
- D Schneberger
- Pulmonary, Critical Care, Sleep & Allergy Division, Department of Internal Medicine, University of Nebraska Medical Center, 985910 The Nebraska Medical Center, Omaha, NE 68198-5910, United States
| | - D Cloonan
- Pulmonary, Critical Care, Sleep & Allergy Division, Department of Internal Medicine, University of Nebraska Medical Center, 985910 The Nebraska Medical Center, Omaha, NE 68198-5910, United States
| | - J M DeVasure
- Pulmonary, Critical Care, Sleep & Allergy Division, Department of Internal Medicine, University of Nebraska Medical Center, 985910 The Nebraska Medical Center, Omaha, NE 68198-5910, United States
| | - K L Bailey
- Research Service, Veterans Administration Nebraska Western Iowa Health Care System, Omaha, NE 68105, United States; Pulmonary, Critical Care, Sleep & Allergy Division, Department of Internal Medicine, University of Nebraska Medical Center, 985910 The Nebraska Medical Center, Omaha, NE 68198-5910, United States
| | - D J Romberger
- Research Service, Veterans Administration Nebraska Western Iowa Health Care System, Omaha, NE 68105, United States; Pulmonary, Critical Care, Sleep & Allergy Division, Department of Internal Medicine, University of Nebraska Medical Center, 985910 The Nebraska Medical Center, Omaha, NE 68198-5910, United States
| | - T A Wyatt
- Research Service, Veterans Administration Nebraska Western Iowa Health Care System, Omaha, NE 68105, United States; Pulmonary, Critical Care, Sleep & Allergy Division, Department of Internal Medicine, University of Nebraska Medical Center, 985910 The Nebraska Medical Center, Omaha, NE 68198-5910, United States; Department of Environmental, Agricultural and Occupational Health, College of Public Health, University of Nebraska Medical Center, 985910 The Nebraska Medical Center, Omaha, NE 68198-5910, United States.
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13
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Morimont P, Batchinsky A, Lambermont B. Update on the role of extracorporeal CO₂ removal as an adjunct to mechanical ventilation in ARDS. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2015; 19:117. [PMID: 25888428 PMCID: PMC4360937 DOI: 10.1186/s13054-015-0799-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2015 and co-published as a series in Critical Care. Other articles in the series can be found online at http://ccforum.com/series/annualupdate2015. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.
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Affiliation(s)
- Philippe Morimont
- Department of Internal Medicine, Medical and Coronary Intensive Care Unit, University Hospital of Liege, Liege, Belgium.
| | - Andriy Batchinsky
- Fort Sam Houston, U.S. Army Institute of Surgical Research, Battlefield Health and Trauma Research Institute, San Antonio, USA.
| | - Bernard Lambermont
- Department of Internal Medicine, Medical and Coronary Intensive Care Unit, University Hospital of Liege, Liege, Belgium.
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14
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15
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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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16
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Hayes M, Curley GF, Masterson C, Contreras M, Ansari B, Devaney J, O'Toole D, Laffey JG. Pulmonary overexpression of inhibitor κBα decreases the severity of ventilator-induced lung injury in a rat model. Br J Anaesth 2014; 113:1046-54. [PMID: 25053119 DOI: 10.1093/bja/aeu225] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Activation of the nuclear factor-κB (NF-κB) pathway is central to the pathogenesis of lung injury and inflammation. We determined whether targeted overexpression of inhibitor-κBα (IκBα) in the lung could decrease the severity of ventilator-induced lung injury (VILI). METHODS Anaesthetized adult male Sprague-Dawley rats were randomly allocated to undergo intratracheal instillation of: (i) vehicle alone (surfactant, n=10); (ii) 1×10(10) adeno-associated virus encoding IκBα (AAV-IκBα, n=10); (iii) 5×10(10) AAV-IκBα (n=10); and (iv) 1×10(10) AAV-Null (n=5). This was followed by 4 h of injurious mechanical ventilation. Subsequent experiments examined the effect of IκBα overexpression in animals undergoing 'protective' mechanical ventilation. RESULTS IκBα overexpression increased survival duration at both the lower [3.8 h (0.4)] and higher [3.6 h (0.7)] doses compared with vehicle [2.7 h (1.0)] or the null transgene [2.2 h (0.8)]. IκBα overexpression reduced the alveolar-arterial oxygen gradient (kPa) at both the lower [53 (21)] and higher [52 (19)] doses compared with vehicle [75 (8.5)] or the null transgene [70 (15)], decreased alveolar neutrophil infiltration, and reduced alveolar concentrations of interleukin (IL)-1β and IL-10. The lower IκBα dose was as effective as the higher dose. IκBα overexpression had no effect in the setting of protective lung ventilation. CONCLUSIONS Inhibition of pulmonary NF-κB activity by IκBα overexpression reduced the severity of VILI in a rat model.
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Affiliation(s)
- M Hayes
- Lung Biology Group, Regenerative Medicine Institute, National University of Ireland, Galway, Ireland Anaesthesia, School of Medicine, Clinical Sciences Institute, National University of Ireland, Galway, Ireland
| | - G F Curley
- Lung Biology Group, Regenerative Medicine Institute, National University of Ireland, Galway, Ireland Department of Anaesthesia, Keenan Research Centre for Biomedical Science, St Michael's Hospital, University of Toronto, Toronto, Canada
| | - C Masterson
- Lung Biology Group, Regenerative Medicine Institute, National University of Ireland, Galway, Ireland Anaesthesia, School of Medicine, Clinical Sciences Institute, National University of Ireland, Galway, Ireland
| | - M Contreras
- Lung Biology Group, Regenerative Medicine Institute, National University of Ireland, Galway, Ireland Anaesthesia, School of Medicine, Clinical Sciences Institute, National University of Ireland, Galway, Ireland
| | - B Ansari
- Lung Biology Group, Regenerative Medicine Institute, National University of Ireland, Galway, Ireland Anaesthesia, School of Medicine, Clinical Sciences Institute, National University of Ireland, Galway, Ireland
| | - J Devaney
- Lung Biology Group, Regenerative Medicine Institute, National University of Ireland, Galway, Ireland Anaesthesia, School of Medicine, Clinical Sciences Institute, National University of Ireland, Galway, Ireland
| | - D O'Toole
- Lung Biology Group, Regenerative Medicine Institute, National University of Ireland, Galway, Ireland Anaesthesia, School of Medicine, Clinical Sciences Institute, National University of Ireland, Galway, Ireland
| | - J G Laffey
- Lung Biology Group, Regenerative Medicine Institute, National University of Ireland, Galway, Ireland Department of Anaesthesia, Keenan Research Centre for Biomedical Science, St Michael's Hospital, University of Toronto, Toronto, Canada
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Cordioli RL, Park M, Costa ELV, Gomes S, Brochard L, Amato MBP, Azevedo LCP. Moderately high frequency ventilation with a conventional ventilator allows reduction of tidal volume without increasing mean airway pressure. Intensive Care Med Exp 2014; 2:13. [PMID: 26266914 PMCID: PMC4512987 DOI: 10.1186/2197-425x-2-13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 03/21/2014] [Indexed: 11/10/2022] Open
Abstract
Background The aim of this study was to explore if positive-pressure ventilation delivered by a conventional ICU ventilator at a moderately high frequency (HFPPV) allows a safe reduction of tidal volume (VT) below 6 mL/kg in a porcine model of severe acute respiratory distress syndrome (ARDS) and at a lower mean airway pressure than high-frequency oscillatory ventilation (HFOV). Methods This is a prospective study. In eight pigs (median weight 34 [29,36] kg), ARDS was induced by pulmonary lavage and injurious ventilation. The animals were ventilated with a randomized sequence of respiratory rates: 30, 60, 90, 120, 150, followed by HFOV at 5 Hz. At each step, VT was adjusted to allow partial pressure of arterial carbon dioxide (PaCO2) to stabilize between 57 and 63 mmHg. Data are shown as median [P25th,P75th]. Results After lung injury, the PaO2/FiO2 (P/F) ratio was 92 [63,118] mmHg, pulmonary shunt 26 [17,31]%, and static compliance 11 [8,14] mL/cmH2O. Positive end-expiratory pressure (PEEP) was 14 [10,17] cmH2O. At 30 breaths/min, VT was higher than 6 (7.5 [6.8,10.2]) mL/kg, but at all higher frequencies, VT could be reduced and PaCO2 maintained, leading to reductions in plateau pressures and driving pressures. For frequencies of 60 to 150/min, VT progressively fell from 5.2 [5.1,5.9] to 3.8 [3.7,4.2] mL/kg (p < 0.001). There were no detrimental effects in terms of lung mechanics, auto-PEEP generation, hemodynamics, or gas exchange. Mean airway pressure was maintained constant and was increased only during HFOV. Conclusions During protective mechanical ventilation, HFPPV delivered by a conventional ventilator in a severe ARDS swine model safely allows further tidal volume reductions. This strategy also allowed decreasing airway pressures while maintaining stable PaCO2 levels.
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Affiliation(s)
- Ricardo Luiz Cordioli
- Research and Education Institute, Hospital Sírio-Libanês, Rua Dona Adma Jafet, 91, Bela Vista, São Paulo, 01308-050, Brazil,
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18
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Gates KL, Howell HA, Nair A, Vohwinkel CU, Welch LC, Beitel GJ, Hauser AR, Sznajder JI, Sporn PHS. Hypercapnia impairs lung neutrophil function and increases mortality in murine pseudomonas pneumonia. Am J Respir Cell Mol Biol 2013; 49:821-8. [PMID: 23777386 DOI: 10.1165/rcmb.2012-0487oc] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Hypercapnia, an elevation of the level of carbon dioxide (CO2) in blood and tissues, is a marker of poor prognosis in chronic obstructive pulmonary disease and other pulmonary disorders. We previously reported that hypercapnia inhibits the expression of TNF and IL-6 and phagocytosis in macrophages in vitro. In the present study, we determined the effects of normoxic hypercapnia (10% CO2, 21% O2, and 69% N2) on outcomes of Pseudomonas aeruginosa pneumonia in BALB/c mice and on pulmonary neutrophil function. We found that the mortality of P. aeruginosa pneumonia was increased in 10% CO2-exposed compared with air-exposed mice. Hypercapnia increased pneumonia mortality similarly in mice with acute and chronic respiratory acidosis, indicating an effect unrelated to the degree of acidosis. Exposure to 10% CO2 increased the burden of P. aeruginosa in the lungs, spleen, and liver, but did not alter lung injury attributable to pneumonia. Hypercapnia did not reduce pulmonary neutrophil recruitment during infection, but alveolar neutrophils from 10% CO2-exposed mice phagocytosed fewer bacteria and produced less H2O2 than neutrophils from air-exposed mice. Secretion of IL-6 and TNF in the lungs of 10% CO2-exposed mice was decreased 7 hours, but not 15 hours, after the onset of pneumonia, indicating that hypercapnia inhibited the early cytokine response to infection. The increase in pneumonia mortality caused by elevated CO2 was reversible when hypercapnic mice were returned to breathing air before or immediately after infection. These results suggest that hypercapnia may increase the susceptibility to and/or worsen the outcome of lung infections in patients with severe lung disease.
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Affiliation(s)
- Khalilah L Gates
- 1 Division of Pulmonary and Critical Care Medicine, Department of Medicine
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19
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Stübs CC, Picker O, Schulz J, Obermiller K, Barthel F, Hahn AM, Bauer I, Beck C. Acute, short-term hypercapnia improves microvascular oxygenation of the colon in an animal model of sepsis. Microvasc Res 2013; 90:180-6. [DOI: 10.1016/j.mvr.2013.07.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 06/25/2013] [Accepted: 07/22/2013] [Indexed: 12/13/2022]
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20
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Cummins EP, Selfridge AC, Sporn PH, Sznajder JI, Taylor CT. Carbon dioxide-sensing in organisms and its implications for human disease. Cell Mol Life Sci 2013; 71:831-45. [PMID: 24045706 DOI: 10.1007/s00018-013-1470-6] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 08/22/2013] [Accepted: 08/30/2013] [Indexed: 12/29/2022]
Abstract
The capacity of organisms to sense changes in the levels of internal and external gases and to respond accordingly is central to a range of physiologic and pathophysiologic processes. Carbon dioxide, a primary product of oxidative metabolism is one such gas that can be sensed by both prokaryotic and eukaryotic cells and in response to altered levels, elicit the activation of multiple adaptive pathways. The outcomes of activating CO2-sensitive pathways in various species include increased virulence of fungal and bacterial pathogens, prey-seeking behavior in insects as well as taste perception, lung function, and the control of immunity in mammals. In this review, we discuss what is known about the mechanisms underpinning CO2 sensing across a range of species and consider the implications of this for physiology, disease progression, and the possibility of developing new therapeutics for inflammatory and infectious disease.
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Affiliation(s)
- Eoin P Cummins
- School of Medicine and Medical Science, UCD Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
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21
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Yalındağ-Öztürk N, Vuran C, Karakoç F, Ersu R. Use of pumpless extracorporeal lung assist as rescue therapy in adolescent with cystic fibrosis. Pediatr Int 2013; 55:e83-5. [PMID: 23910813 DOI: 10.1111/ped.12129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 12/07/2011] [Accepted: 02/08/2013] [Indexed: 11/28/2022]
Abstract
There is abundant evidence that artificial ventilation can aggravate pre-existing lung disease, which may contribute to morbidity and mortality. This is especially true for patients with air leakages. This case report describes the use of a pumpless extracorporeal lung assist as a rescue therapy to provide time to heal during the mechanical ventilation of a 16-year-old with cystic fibrosis who could not be managed via conventional means.
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Affiliation(s)
- Nilüfer Yalındağ-Öztürk
- Division of Pediatric Critical Care, Department of Pediatrics, Başkent University Medical Research and Treatment Center in Istanbul, Turkey.
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Obiako B, Calchary W, Xu N, Kunstadt R, Richardson B, Nix J, Sayner SL. Bicarbonate disruption of the pulmonary endothelial barrier via activation of endogenous soluble adenylyl cyclase, isoform 10. Am J Physiol Lung Cell Mol Physiol 2013; 305:L185-92. [PMID: 23686854 PMCID: PMC3726949 DOI: 10.1152/ajplung.00392.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 05/14/2013] [Indexed: 01/23/2023] Open
Abstract
It is becoming increasingly apparent that cAMP signals within the pulmonary endothelium are highly compartmentalized, and this compartmentalization is critical to maintaining endothelial barrier integrity. Studies demonstrate that the exogenous soluble bacterial toxin, ExoY, and heterologous expression of the forskolin-stimulated soluble mammalian adenylyl cyclase (AC) chimera, sACI/II, elevate cytosolic cAMP and disrupt the pulmonary microvascular endothelial barrier. The barrier-disruptive effects of cytosolic cAMP generated by exogenous soluble ACs are in contrast to the barrier-protective effects of subplasma membrane cAMP generated by transmembrane AC, which strengthens endothelial barrier integrity. Endogenous soluble AC isoform 10 (AC10 or commonly known as sAC) lacks transmembrane domains and localizes within the cytosolic compartment. AC10 is uniquely activated by bicarbonate to generate cytosolic cAMP, yet its role in regulation of endothelial barrier integrity has not been addressed. Here we demonstrate that, within the pulmonary circulation, AC10 is expressed in pulmonary microvascular endothelial cells (PMVECs) and pulmonary artery endothelial cells (PAECs), yet expression in PAECs is lower. Furthermore, pulmonary endothelial cells selectively express bicarbonate cotransporters. While extracellular bicarbonate generates a phosphodiesterase 4-sensitive cAMP pool in PMVECs, no such cAMP response is detected in PAECs. Finally, addition of extracellular bicarbonate decreases resistance across the PMVEC monolayer and increases the filtration coefficient in the isolated perfused lung above osmolality controls. Collectively, these findings suggest that PMVECs have a bicarbonate-sensitive cytosolic cAMP pool that disrupts endothelial barrier integrity. These studies could provide an alternative mechanism for the controversial effects of bicarbonate correction of acidosis of acute respiratory distress syndrome patients.
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Affiliation(s)
- Boniface Obiako
- Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, AL 36688, USA
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23
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Weber T, Schiebenpflug C, Deusch E. Inhalational sevoflurane in severe bronchial obstruction unresponsive to multipharmacologic therapy: a case report. F1000Res 2012; 1:56. [PMID: 24358829 PMCID: PMC3790599 DOI: 10.12688/f1000research.1-56.v1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/21/2012] [Indexed: 11/30/2022] Open
Abstract
Introduction: Bronchial asthma with respiratory failure is a challenge for the intensivist as mechanical ventilation is often difficult due to bronchoconstriction and air-trapping. We describe a case of severe asthma with respiratory acidosis in a 10-year-old patient unresponsive to multipharmacologic broncholytic therapy. Only the initiation of sevoflurane inhalation resolved severe bronchoconstriction and dynamic hyperinflation, leading to complete recovery. Case presentation: A 10-year-old Caucasian boy was intubated and mechanically ventilated due to an asthmatic attack. Bronchoconstriction and dynamic hyperinflation were severe while multipharmacological broncholytic therapy was unsuccessful. Inhalation with sevoflurane via an anaesthesia machine was the key intervention leading to gradual resolving of severe hypercapnia and respiratory acidosis. Furthermore bilateral pupil dilation occurred during hypercapnia, but no intracranial pathology could be detected. The patient made an uneventful recovery. To our knowledge this is the first case where hypercapnia and respiratory acidosis were so profound and long lasting yet the patient survived without any damage. Conclusions: Inhalational anaesthetics must be considered as an early treatment option in ventilated asthmatic patients with bronchial obstruction unresponsive to conventional therapy even though their administration in intensive care units may be difficult.
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Affiliation(s)
- Thomas Weber
- Department of Anaesthesiology and Intensive Care, Sozialmedizinisches Zentrum Ost-Donauspital, Langobardenstr. 122, Vienna, Austria
| | - Christian Schiebenpflug
- Department of Anaesthesiology and Intensive Care, Sozialmedizinisches Zentrum Ost-Donauspital, Langobardenstr. 122, Vienna, Austria
| | - Engelbert Deusch
- Department of Anaesthesiology and Intensive Care, Otto-Wagner-Spital, Sanatoriumsstrasse 1, 1140 Vienna, Austria
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Hypercapnic acidosis attenuates ventilation-induced lung injury by a nuclear factor-κB–dependent mechanism. Crit Care Med 2012; 40:2622-30. [DOI: 10.1097/ccm.0b013e318258f8b4] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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25
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Cook ZC, Gray MA, Cann MJ. Elevated carbon dioxide blunts mammalian cAMP signaling dependent on inositol 1,4,5-triphosphate receptor-mediated Ca2+ release. J Biol Chem 2012; 287:26291-301. [PMID: 22654111 PMCID: PMC3406713 DOI: 10.1074/jbc.m112.349191] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 05/15/2012] [Indexed: 12/11/2022] Open
Abstract
Elevated CO(2) is generally detrimental to animal cells, suggesting an interaction with core processes in cell biology. We demonstrate that elevated CO(2) blunts G protein-activated cAMP signaling. The effect of CO(2) is independent of changes in intracellular and extracellular pH, independent of the mechanism used to activate the cAMP signaling pathway, and is independent of cell context. A combination of pharmacological and genetic tools demonstrated that the effect of elevated CO(2) on cAMP levels required the activity of the IP(3) receptor. Consistent with these findings, CO(2) caused an increase in steady state cytoplasmic Ca(2+) concentrations not observed in the absence of the IP(3) receptor or under nonspecific acidotic conditions. We examined the well characterized cAMP-dependent inhibition of the isoform 3 Na(+)/H(+) antiporter (NHE3) to demonstrate a functional relevance for CO(2)-mediated reductions in cellular cAMP. Consistent with the cellular biochemistry, elevated CO(2) abrogated the inhibitory effect of cAMP on NHE3 function via an IP(3) receptor-dependent mechanism.
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Affiliation(s)
- Zara C. Cook
- From the School of Biological and Biomedical Sciences and
- Biophysical Sciences Institute, Durham University, South Road, Durham DH1 3LE, United Kingdom and
| | - Michael A. Gray
- Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - Martin J. Cann
- From the School of Biological and Biomedical Sciences and
- Biophysical Sciences Institute, Durham University, South Road, Durham DH1 3LE, United Kingdom and
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Oliver KM, Lenihan CR, Bruning U, Cheong A, Laffey JG, McLoughlin P, Taylor CT, Cummins EP. Hypercapnia induces cleavage and nuclear localization of RelB protein, giving insight into CO2 sensing and signaling. J Biol Chem 2012; 287:14004-11. [PMID: 22396550 PMCID: PMC3340129 DOI: 10.1074/jbc.m112.347971] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Carbon dioxide (CO2) is increasingly being appreciated as an intracellular signaling molecule that affects inflammatory and immune responses. Elevated arterial CO2 (hypercapnia) is encountered in a range of clinical conditions, including chronic obstructive pulmonary disease, and as a consequence of therapeutic ventilation in acute respiratory distress syndrome. In patients suffering from this syndrome, therapeutic hypoventilation strategy designed to reduce mechanical damage to the lungs is accompanied by systemic hypercapnia and associated acidosis, which are associated with improved patient outcome. However, the molecular mechanisms underlying the beneficial effects of hypercapnia and the relative contribution of elevated CO2 or associated acidosis to this response remain poorly understood. Recently, a role for the non-canonical NF-κB pathway has been postulated to be important in signaling the cellular transcriptional response to CO2. In this study, we demonstrate that in cells exposed to elevated CO2, the NF-κB family member RelB was cleaved to a lower molecular weight form and translocated to the nucleus in both mouse embryonic fibroblasts and human pulmonary epithelial cells (A549). Furthermore, elevated nuclear RelB was observed in vivo and correlated with hypercapnia-induced protection against LPS-induced lung injury. Hypercapnia-induced RelB processing was sensitive to proteasomal inhibition by MG-132 but was independent of the activity of glycogen synthase kinase 3β or MALT-1, both of which have been previously shown to mediate RelB processing. Taken together, these data demonstrate that RelB is a CO2-sensitive NF-κB family member that may contribute to the beneficial effects of hypercapnia in inflammatory diseases of the lung.
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Affiliation(s)
- Kathryn M Oliver
- School of Medicine and Medical Science, UCD Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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27
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Aslami H, Kuipers MT, Beurskens CJP, Roelofs JJTH, Schultz MJ, Juffermans NP. Mild hypothermia reduces ventilator-induced lung injury, irrespective of reducing respiratory rate. Transl Res 2012; 159:110-7. [PMID: 22243795 DOI: 10.1016/j.trsl.2011.10.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 10/13/2011] [Accepted: 10/14/2011] [Indexed: 10/15/2022]
Abstract
In the era of lung-protective mechanical ventilation using limited tidal volumes, higher respiratory rates are applied to maintain adequate minute volume ventilation. However, higher respiratory rates may contribute to ventilator-induced lung injury (VILI). Induced hypothermia reduces carbon dioxide production and might allow for lower respiratory rates during mechanical ventilation. We hypothesized that hypothermia protects from VILI and investigated whether reducing respiratory rates enhance lung protection in an in vivo model of VILI. During 4 h of mechanical ventilation, VILI was induced by tidal volumes of 18 mL/kg in rats, with respiratory rates set at 15 or 10 breaths/min in combination with hypothermia (32°C) or normothermia (37°C). Hypothermia was induced by external cooling. A physiologic model was established. VILI was characterized by increased pulmonary neutrophil influx, protein leak, wet weights, histopathology score, and cytokine levels compared with lung protective mechanical ventilation. Hypothermia decreased neutrophil influx, pulmonary levels, systemic interleukin-6 levels, and histopathology score, and it tended to decrease the pulmonary protein leak. Reducing the respiratory rate in combination with hypothermia did not reduce the parameters of the lung injury. In conclusion, hypothermia protected from lung injury in a physiologic VILI model by reducing inflammation. Decreasing the respiratory rate mildly did not enhance protection.
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Affiliation(s)
- Hamid Aslami
- Laboratory of Experimental Intensive Care and Anesthesiology, Academic Medical Center, Meibergdreef 9, Amsterdam, the Netherlands.
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Vadász I, Hubmayr RD, Nin N, Sporn PHS, Sznajder JI. Hypercapnia: a nonpermissive environment for the lung. Am J Respir Cell Mol Biol 2012; 46:417-21. [PMID: 22246860 DOI: 10.1165/rcmb.2011-0395ps] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Patients with severe acute and chronic lung diseases develop derangements in gas exchange that may result in increased levels of CO(2) (hypercapnia), the effects of which on human health are incompletely understood. It has been proposed that hypercapnia may have beneficial effects in patients with acute lung injury, and the concepts of "permissive" and even "therapeutic" hypercapnia have emerged. However, recent work suggests that CO(2) can act as a signaling molecule via pH-independent mechanisms, resulting in deleterious effects in the lung. Here we review recent research on how elevated CO(2) is sensed by cells in the lung and the potential harmful effects of hypercapnia on epithelial and endothelial barrier, lung edema clearance, innate immunity, and host defense. In view of these findings, we raise concerns about the potentially deleterious effects hypercapnia may have in patients with acute and chronic lung diseases.
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Affiliation(s)
- István Vadász
- Department of Internal Medicine, University of Giessen Lung Center, Justus Liebig University, Germany.
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Jung B, Rimmele T, Le Goff C, Chanques G, Corne P, Jonquet O, Muller L, Lefrant JY, Guervilly C, Papazian L, Allaouchiche B, Jaber S. Severe metabolic or mixed acidemia on intensive care unit admission: incidence, prognosis and administration of buffer therapy. A prospective, multiple-center study. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2011; 15:R238. [PMID: 21995879 PMCID: PMC3334789 DOI: 10.1186/cc10487] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Revised: 09/06/2011] [Accepted: 10/13/2011] [Indexed: 12/23/2022]
Abstract
Introduction In this study, we sought describe the incidence and outcomes of severe metabolic or mixed acidemia in critically ill patients as well as the use of sodium bicarbonate therapy to treat these illnesses. Methods We conducted a prospective, observational, multiple-center study. Consecutive patients who presented with severe acidemia, defined herein as plasma pH below 7.20, were screened. The incidence, sodium bicarbonate prescription and outcomes of either metabolic or mixed severe acidemia were analyzed. Results Among 2, 550 critically ill patients, 200 (8%) presented with severe acidemia, and 155 (6% of the total admissions) met the inclusion criteria. Almost all patients needed mechanical ventilation and vasopressors during their ICU stay, and 20% of them required renal replacement therapy within the first 24 hours of their ICU stay. Severe metabolic or mixed acidemia was associated with a mortality rate of 57% in the ICU. Delay of acidemia recovery as opposed to initial pH value was associated with increased mortality in the ICU. The type of acidemia did not influence the decision to administer sodium bicarbonate. Conclusions The incidence of severe metabolic or mixed acidemia in critically ill patients was 6% in the present study, and it was associated with a 57% mortality rate in the ICU. In contradistinction with the initial acid-base parameters, the rapidity of acidemia recovery was an independent risk factor for mortality. Sodium bicarbonate prescription was very heterogeneous between ICUs. Further studies assessing specific treatments may be of interest in this population.
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Affiliation(s)
- Boris Jung
- Intensive Care Unit, Department of Anaesthesia and Critical Care, Saint Eloi Teaching Hospital, Université Montpellier 1, 80 avenue Augustin Fliche, F-34295 Montpellier, Cedex 5, France
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Therapeutic hypercapnia enhances the inflammatory response to endotoxin in the lung of spontaneously breathing rats*. Crit Care Med 2011; 39:1400-6. [DOI: 10.1097/ccm.0b013e31820ee1f2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Curley G, Hayes M, Laffey JG. Can 'permissive' hypercapnia modulate the severity of sepsis-induced ALI/ARDS? CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2011; 15:212. [PMID: 21457509 PMCID: PMC3219408 DOI: 10.1186/cc9994] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Gerard Curley
- Department of Anestheisa, Clinical Sciences Institute, National University, Galway, Ireland
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Abstract
Carbon dioxide (CO(2)) is a physiological gas found at low levels in the atmosphere and produced in cells during the process of aerobic respiration. Consequently, the levels of CO(2) within tissues are usually significantly higher than those found externally. Shifts in tissue levels of CO(2) (leading to either hypercapnia or hypocapnia) are associated with a number of pathophysiological conditions in humans and can occur naturally in niche habitats such as those of burrowing animals. Clinical studies have indicated that such altered CO(2) levels can impact upon disease progression. Recent advances in our understanding of the biology of CO(2) has shown that like other physiological gases such as molecular oxygen (O(2)) and nitric oxide (NO), CO(2) levels can be sensed by cells resulting in the initiation of physiological and pathophysiological responses. Acute CO(2) sensing in neurons and peripheral and central chemoreceptors is important in rapidly activated responses including olfactory signalling, taste sensation and cardiorespiratory control. Furthermore, a role for CO(2) in the regulation of gene transcription has recently been identified with exposure of cells and model organisms to high CO(2) leading to suppression of genes involved in the regulation of innate immunity and inflammation. This latter, transcriptional regulatory role for CO(2), has been largely attributed to altered activity of the NF-B family of transcription factors. Here, we review our evolving understanding of how CO(2) impacts upon gene transcription.
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Affiliation(s)
- Cormac T Taylor
- UCD Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland.
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Honoré PM, Jacobs R, Boer W, Joannes-Boyau O. Sepsis and AKI: more complex than just a simple question of chicken and egg. Intensive Care Med 2010; 37:186-9. [PMID: 21152897 DOI: 10.1007/s00134-010-2097-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 11/10/2010] [Indexed: 01/20/2023]
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Bench-to-bedside review: hypercapnic acidosis in lung injury--from 'permissive' to 'therapeutic'. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2010; 14:237. [PMID: 21067531 PMCID: PMC3220022 DOI: 10.1186/cc9238] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Modern ventilation strategies for patients with acute lung injury and acute respiratory distress syndrome frequently result in hypercapnic acidosis (HCA), which is regarded as an acceptable side effect ('permissive hypercapnia'). Multiple experimental studies have demonstrated advantageous effects of HCA in several lung injury models. To date, however, human trials studying the effect of carbon dioxide per se on outcome in patients with lung injury have not been performed. While significant concerns regarding HCA remain, in particular the possible unfavorable effects on bacterial killing and the inhibition of pulmonary epithelial wound repair, the potential for HCA in attenuating lung injury is promising. The underlying mechanisms by which HCA exerts its protective effects are complex, but dampening of the inflammatory response seems to play a pivotal role. After briefly summarizing the physiological effects of HCA, a critical analysis of the available evidence on the potential beneficial effects of therapeutic HCA from in vitro, ex vivo and in vivo lung injury models and from human studies will be reviewed. In addition, the potential concerns in the clinical setting will be outlined.
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Cummins EP, Oliver KM, Lenihan CR, Fitzpatrick SF, Bruning U, Scholz CC, Slattery C, Leonard MO, McLoughlin P, Taylor CT. NF-κB Links CO2 Sensing to Innate Immunity and Inflammation in Mammalian Cells. THE JOURNAL OF IMMUNOLOGY 2010; 185:4439-45. [DOI: 10.4049/jimmunol.1000701] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Abstract
Carbon dioxide is a waste product of aerobic cellular respiration in all aerobic life forms. PaCO2 represents the balance between the carbon dioxide produced and that eliminated. Hypocapnia remains a common - and generally underappreciated - component of many disease states, including early asthma, high-altitude pulmonary edema, and acute lung injury. Induction of hypocapnia remains a common, if controversial, practice in both adults and children with acute brain injury. In contrast, hypercapnia has traditionally been avoided in order to keep parameters normal. More recently, advances in our understanding of the role of excessive tidal volume has prompted clinicians to use ventilation strategies that result in hypercapnia. Consequently, hypercapnia has become increasingly prevalent in the critically ill patient. Hypercapnia may play a beneficial role in the pathogenesis of inflammation and tissue injury, but may hinder the host response to sepsis and reduce repair. In contrast, hypocapnia may be a pathogenic entity in the setting of critical illness. The present paper reviews the current clinical status of low and high PaCO2 in the critically ill patient, discusses the insights gained to date from studies of carbon dioxide, identifies key concerns regarding hypocapnia and hypercapnia, and considers the potential clinical implications for the management of patients with acute lung injury.
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Affiliation(s)
- Gerard Curley
- Department of Anaesthesia, Clinical Sciences Institute, National University of Ireland, Galway, Ireland
- Lung Biology Group, National Centre of Biomedical Engineering Sciences, National University of Ireland, Galway, Ireland
| | - John G Laffey
- Department of Anaesthesia, Clinical Sciences Institute, National University of Ireland, Galway, Ireland
- Lung Biology Group, National Centre of Biomedical Engineering Sciences, National University of Ireland, Galway, Ireland
| | - Brian P Kavanagh
- Departments of Critical Care Medicine and Anesthesia and the Program in Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, 555 university Avenue, Toronto, ON M5G 1X8, Canada
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