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Laghi F, Shaikh H, Caccani N. Basing intubation of acutely hypoxemic patients on physiologic principles. Ann Intensive Care 2024; 14:86. [PMID: 38864960 DOI: 10.1186/s13613-024-01327-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 05/31/2024] [Indexed: 06/13/2024] Open
Abstract
The decision to intubate a patient with acute hypoxemic respiratory failure who is not in apparent respiratory distress is one of the most difficult clinical decisions faced by intensivists. A conservative approach exposes patients to the dangers of hypoxemia, while a liberal approach exposes them to the dangers of inserting an endotracheal tube and invasive mechanical ventilation. To assist intensivists in this decision, investigators have used various thresholds of peripheral or arterial oxygen saturation, partial pressure of oxygen, partial pressure of oxygen-to-fraction of inspired oxygen ratio, and arterial oxygen content. In this review we will discuss how each of these oxygenation indices provides inaccurate information about the volume of oxygen transported in the arterial blood (convective oxygen delivery) or the pressure gradient driving oxygen from the capillaries to the cells (diffusive oxygen delivery). The decision to intubate hypoxemic patients is further complicated by our nescience of the critical point below which global and cerebral oxygen supply become delivery-dependent in the individual patient. Accordingly, intubation requires a nuanced understanding of oxygenation indexes. In this review, we will also discuss our approach to intubation based on clinical observations and physiologic principles. Specifically, we consider intubation when hypoxemic patients, who are neither in apparent respiratory distress nor in shock, become cognitively impaired suggesting emergent cerebral hypoxia. When deciding to intubate, we also consider additional factors including estimates of cardiac function, peripheral perfusion, arterial oxygen content and its determinants. It is not possible, however, to pick an oxygenation breakpoint below which the benefits of mechanical ventilation decidedly outweigh its hazards. It is futile to imagine that decision making about instituting mechanical ventilation in an individual patient can be condensed into an algorithm with absolute numbers at each nodal point. In sum, an algorithm cannot replace the presence of a physician well skilled in the art of clinical evaluation who has a deep understanding of pathophysiologic principles.
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Affiliation(s)
- Franco Laghi
- Division of Pulmonary and Critical Care Medicine, Hines Veterans Affairs Hospital (111N) and Loyola University of Chicago Stritch School of Medicine, 60141, Hines, IL, USA.
| | - Hameeda Shaikh
- Division of Pulmonary and Critical Care Medicine, Hines Veterans Affairs Hospital (111N) and Loyola University of Chicago Stritch School of Medicine, 60141, Hines, IL, USA
| | - Nicola Caccani
- Department of Physiology and Pharmacology, Center for Molecular Medicine, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Brandt JS, Ananth CV. Placental abruption at near-term and term gestations: pathophysiology, epidemiology, diagnosis, and management. Am J Obstet Gynecol 2023; 228:S1313-S1329. [PMID: 37164498 PMCID: PMC10176440 DOI: 10.1016/j.ajog.2022.06.059] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2021] [Revised: 06/27/2022] [Accepted: 06/29/2022] [Indexed: 05/12/2023]
Abstract
Placental abruption is the premature separation of the placenta from its uterine attachment before the delivery of a fetus. The clinical manifestations of abruption typically include vaginal bleeding and abdominal pain with a wide variety of abnormal fetal heart rate patterns. Clinical challenges arise when pregnant people with this condition present with profound vaginal bleeding, necessitating urgent delivery, especially when there is a concern for maternal and fetal compromise and coagulopathy. Abruption occurs in 0.6% to 1.2% of all pregnancies, with nearly half of abruption occurring at term gestations. An exposition of abruption at near-term (defined as the late preterm period from 34 0/7 to 36 6/7 weeks of gestation) and term (defined as ≥37 weeks of gestation) provides unique insights into its direct effects, as risks associated with preterm birth do not impact outcomes. Here, we explore the pathophysiology, epidemiology, and diagnosis of abruption. We discuss the interaction of chronic processes (decidual and uteroplacental vasculopathy) and acute processes (shearing forces applied to the abdomen) that underlie the pathophysiology. Risk factors for abruption and strengths of association are summarized. Sonographic findings of abruption and fetal heart rate tracings are presented. In addition, we propose a management algorithm for acute abruption that incorporates blood loss, vital signs, and urine output, among other factors. Lastly, we discuss blood component therapy, viscoelastic point-of-care testing, disseminated intravascular coagulopathy, and management of abruption complicated by fetal death. The review seeks to provide comprehensive, clinically focused guidance during a gestational age range when neonatal outcomes can often be favorable if rapid and evidence-based care is optimized.
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Affiliation(s)
- Justin S Brandt
- Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ.
| | - Cande V Ananth
- Division of Epidemiology and Biostatistics, Department of Obstetrics, Gynecology, and Reproductive Sciences, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ; Department of Biostatistics and Epidemiology, Rutgers School of Public Health, Piscataway, NJ; Cardiovascular Institute of New Jersey and Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ; Environmental and Occupational Health Sciences Institute, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ
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Köhler D, Voshaar T, Stais P, Haidl P, Dellweg D. Hypoxische, anämische und kardial bedingte Hypoxämie: Wann beginnt die Hypoxie im Gewebe? Dtsch Med Wochenschr 2023; 148:475-482. [PMID: 36990120 DOI: 10.1055/a-2007-5450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
ZusammenfassungBei einer Hypoxämie ist oft der Sauerstoffgehalt noch im unteren Normbereich, sodass keine
Hypoxie im Gewebe vorliegt. Wird die Hypoxie-Schwelle im Gewebe bei einer hypoxisch, anämisch
und auch kardial bedingten Hypoxämie erreicht, kommt es im Zellstoffwechsel, unabhängig von
der Genese, zu identischen Gegenregulationen. Im klinischen Alltag wird diese
pathophysiologische Tatsache mitunter ignoriert, obwohl je nach Hypoxämie-Ursache die
Beurteilung und die Therapie stark unterschiedlich sind. Während für die anämische Hypoxämie
restriktive und allgemein akzeptierte Regeln in den Transfusionsrichtlinien festgelegt sind,
wird bei einer hypoxischen Hypoxie früh die Indikation zu einer meist invasiven Beatmung
gestellt. Die klinische Beurteilung und Indikationsstellung fokussiert dabei auf die Parameter
Sauerstoffsättigung, Sauerstoffpartialdruck und Oxygenierungsindex. Während der
Corona-Pandemie sind Fehlinterpretationen der Pathophysiologie sichtbar geworden und haben
vermutlich zu überflüssigen Intubationen geführt. Für die Behandlung einer hypoxischen Hypoxie
mittels invasiver Beatmung aber gibt es keine Evidenz. Im vorliegenden Review wird auf die
Pathophysiologie der verschiedenen Hypoxieursachen unter besonderer Berücksichtigung der
Intubation und Beatmung auf der Intensivstation eingegangen.
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Increased ratio of P[v-a]CO 2 to C[a-v]O 2 without global hypoxia: the case of metformin-induced lactic acidosis. Respir Physiol Neurobiol 2020; 285:103586. [PMID: 33202296 DOI: 10.1016/j.resp.2020.103586] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 10/18/2020] [Accepted: 11/11/2020] [Indexed: 12/24/2022]
Abstract
The ratio of venoarterial CO2 tension to arteriovenous O2 content difference (P[v-a]CO2/C[a-v]O2) increases when lactic acidosis is due to inadequate oxygen supply (hypoxia); we aimed to verify whether it also increases when lactic acidosis develops because of mitochondrial dysfunction (dysoxia) with constant oxygen delivery. Twelve anaesthetised, mechanically ventilated pigs were intoxicated with IV metformin (4.0 to 6.4 g over 2.5 to 4.0 h). Saline and norepinephrine were used to preserve oxygen delivery. Lactate and P[v-a]CO2/C[a-v]O2 were measured every one or two hours (arterial and mixed venous blood). During metformin intoxication, lactate increased from 0.8 (0.6-0.9) to 8.5 (5.0-10.9) mmol/l (p < 0.001), even if oxygen delivery remained constant (from 352 ± 78 to 343 ± 97 ml/min, p = 0.098). P[v-a]CO2/C[a-v]O2 increased from 1.6 (1.2-1.8) to 2.3 (1.9-3.2) mmHg/ml/dl (p = 0.004). The intraclass correlation coefficient between lactate and P[v-a]CO2/C[a-v]O2 was 0.72 (p < 0.001). We conclude that P[v-a]CO2/C[a-v]O2 increases when lactic acidosis is due to dysoxia. Therefore, a high P[v-a]CO2/C[a-v]O2 may not discriminate hypoxia from dysoxia as the cause of lactic acidosis.
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Tomic Mahecic T, Dünser M, Meier J. RBC Transfusion Triggers: Is There Anything New? Transfus Med Hemother 2020; 47:361-368. [PMID: 33173454 PMCID: PMC7590774 DOI: 10.1159/000511229] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 08/31/2020] [Indexed: 01/28/2023] Open
Abstract
For many years, in daily clinical practice, the traditional 10/30 rule (hemoglobin 10 g/dL - hematocrit 30%) has been the most commonly used trigger for blood transfusions. Over the years, this approach is believed to have contributed to a countless number of unnecessary transfusions and an unknown number of overtransfusion-related deaths. Recent studies have shown that lower hemoglobin levels can safely be accepted, even in critically ill patients. However, even these new transfusion thresholds are far beyond the theoretical limits of individual anemia tolerance. For this reason, almost all publications addressing the limits of acute anemia recommend physiological transfusion triggers to indicate the transfusion of erythrocyte concentrates as an alternative. Although this concept appears intuitive at first glance, no solid scientific evidence supports the safety and benefit of physiological transfusion triggers to indicate the optimal time point for transfusion of allogeneic blood. It is therefore imperative to continue searching for the most sensitive and specific parameters that can guide the clinician when to transfuse in order to avoid anemia-induced organ dysfunction while avoiding overtransfusion-related adverse effects. This narrative review discusses the concept of anemia tolerance and critically compares hemoglobin-based triggers with physiological transfusion for various clinical indications.
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Affiliation(s)
- Tina Tomic Mahecic
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Center Zagreb − Rebro, Zagreb, Croatia
| | - Martin Dünser
- Department of Anesthesiology and Intensive Care Medicine, Johannes Kepler University, Linz, Austria
| | - Jens Meier
- Department of Anesthesiology and Intensive Care Medicine, Johannes Kepler University, Linz, Austria
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Rosenstein PG, Tennent-Brown BS, Hughes D. Clinical use of plasma lactate concentration. Part 1: Physiology, pathophysiology, and measurement. J Vet Emerg Crit Care (San Antonio) 2018. [PMID: 29533512 DOI: 10.1111/vec.12708] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVE To review the current literature with respect to the physiology, pathophysiology, and measurement of lactate. DATA SOURCES Data were sourced from veterinary and human clinical trials, retrospective studies, experimental studies, and review articles. Articles were retrieved without date restrictions and were sourced primarily via PubMed, Scopus, and CAB Abstracts as well as by manual selection. HUMAN AND VETERINARY DATA SYNTHESIS Lactate is an important energy storage molecule, the production of which preserves cellular energy production and mitigates the acidosis from ATP hydrolysis. Although the most common cause of hyperlactatemia is inadequate tissue oxygen delivery, hyperlactatemia can, and does occur in the face of apparently adequate oxygen supply. At a cellular level, the pathogenesis of hyperlactatemia varies widely depending on the underlying cause. Microcirculatory dysfunction, mitochondrial dysfunction, and epinephrine-mediated stimulation of Na+ -K+ -ATPase pumps are likely important contributors to hyperlactatemia in critically ill patients. Ultimately, hyperlactatemia is a marker of altered cellular bioenergetics. CONCLUSION The etiology of hyperlactatemia is complex and multifactorial. Understanding the relevant pathophysiology is helpful when characterizing hyperlactatemia in clinical patients.
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Affiliation(s)
- Patricia G Rosenstein
- Department of Veterinary Clinical Sciences, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee, Victoria, Australia
| | - Brett S Tennent-Brown
- Department of Veterinary Clinical Sciences, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee, Victoria, Australia
| | - Dez Hughes
- Department of Veterinary Clinical Sciences, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee, Victoria, Australia
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Abstract
Background Fluid resuscitation is not only used to prevent acute kidney injury (AKI) but fluid management is also a cornerstone of treatment for patients with established AKI and renal failure. Ultrafiltration removes volume initially from the intravascular compartment inducing a relative degree of hypovolemia. Normal reflex mechanisms attempt to sustain blood pressure constant despite marked changes in blood volume and cardiac output. Thus, compensated shock with a normal blood pressure is a major cause of AKI or exacerbations of AKI during ultrafiltration. Methods We undertook a systematic review of the literature using MEDLINE, Google Scholar and PubMed searches. We determined a list of key questions and convened a 2-day consensus conference to develop summary statements via a series of alternating breakout and plenary sessions. In these sessions, we identified supporting evidence and generated clinical practice recommendations and/or directions for future research. Results We defined three aspects of fluid monitoring: i) normal and pathophysiological cardiovascular mechanisms; ii) measures of volume responsiveness and impending cardiovascular collapse during volume removal, and; iii) measured indices of each using non-invasive and minimally invasive continuous and intermittent monitoring techniques. The evidence documents that AKI can occur in the setting of normotensive hypovolemia and that under-resuscitation represents a major cause of both AKI and mortality ion critically ill patients. Traditional measures of intravascular volume and ventricular filling do not predict volume responsiveness whereas dynamic functional hemodynamic markers, such as pulse pressure or stroke volume variation during positive pressure breathing or mean flow changes with passive leg raising are highly predictive of volume responsiveness. Numerous commercially-available devices exist that can acquire these signals. Conclusions Prospective clinical trials using functional hemodynamic markers in the diagnosis and management of AKI and volume status during ultrafiltration need to be performed. More traditional measure of preload be abandoned as marked of volume responsiveness though still useful to assess overall volume status.
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Affiliation(s)
- M.R. Pinsky
- Bioengineering, Cardiovascular Diseases and Anesthesiology, University of Pittsburgh Medical Center, Pittsburgh, PA - USA
| | - P. Brophy
- Division of Pediatric Nephrology, Hypertension, Dialysis and Transplantation, University of Iowa, Children's Hospital, Iowa City, Iowa - USA
| | - J. Padilla
- Universidad de Iberoamerica, San Jose - Costa Rica
| | - E. Paganini
- Division of Nephrology, Cleveland Clinic Foundation, Cleveland, OH - USA
| | - N. Pannu
- Division of Nephrology and CCM, University of Alberta, Edmonton, Alberta - Canada
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Santini A, Ronchi D, Garbellini M, Piga D, Protti A. Linezolid-induced lactic acidosis: the thin line between bacterial and mitochondrial ribosomes. Expert Opin Drug Saf 2017; 16:833-843. [PMID: 28538105 DOI: 10.1080/14740338.2017.1335305] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Linezolid inhibits bacterial growth by targeting bacterial ribosomes and by interfering with bacterial protein synthesis. Lactic acidosis is a rare, but potentially lethal, side effect of linezolid. Areas covered: The pathogenesis of linezolid-induced lactic acidosis is reviewed with special emphasis on aspects relevant to the recognition, prevention and treatment of the syndrome. Expert opinion: Linezolid-induced lactic acidosis reflects the untoward interaction between the drug and mitochondrial ribosomes. The inhibition of mitochondrial protein synthesis diminishes the respiratory chain enzyme content and thus limits aerobic energy production. As a result, anaerobic glycolysis and lactate generation accelerate independently from tissue hypoxia. In the absence of any confirmatory test, linezolid-induced lactic acidosis should be suspected only after exclusion of other, more common, causes of lactic acidosis such as hypoxemia, anemia or low cardiac output. Normal-to-high whole-body oxygen delivery, high venous oxygen saturation and lack of response to interventions that effectively increase tissue oxygen provision all suggest a primary defect in oxygen use at the mitochondrial level. During prolonged therapy with linezolid, blood drug and lactate levels should be regularly monitored. The current standard-of-care treatment of linezolid-induced lactic acidosis consists of drug withdrawal to reverse mitochondrial intoxication and intercurrent life support.
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Affiliation(s)
- Alessandro Santini
- a Dipartimento di Anestesia, Rianimazione ed Emergenza-Urgenza , Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico , Milan , Italy
| | - Dario Ronchi
- b Centro Dino Ferrari, Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti , Università degli Studi di Milano , Milan , Italy.,c UOC Neurologia , Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico , Milan , Italy
| | - Manuela Garbellini
- b Centro Dino Ferrari, Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti , Università degli Studi di Milano , Milan , Italy.,c UOC Neurologia , Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico , Milan , Italy
| | - Daniela Piga
- b Centro Dino Ferrari, Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti , Università degli Studi di Milano , Milan , Italy.,c UOC Neurologia , Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico , Milan , Italy
| | - Alessandro Protti
- a Dipartimento di Anestesia, Rianimazione ed Emergenza-Urgenza , Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico , Milan , Italy
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Pavlisko ND, Killos M, Henao-Guerrero N, Riccó CH, Werre S. Evaluation of tissue hemoglobin saturation (StO 2 ) using near-infrared spectroscopy during hypoxemia and hyperoxemia in Beagle dogs. Vet Anaesth Analg 2016; 43:18-26. [DOI: 10.1111/vaa.12258] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Accepted: 10/22/2014] [Indexed: 11/27/2022]
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Spinelli E, Bartlett RH. Anemia and Transfusion in Critical Care. J Intensive Care Med 2015; 31:295-306. [DOI: 10.1177/0885066615571901] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 12/03/2014] [Indexed: 01/28/2023]
Abstract
Objective: The objective of this report is to review the physiology and management of anemia in critical care. Selected publications on physiology and transfusion related to anemia and critical care, including the modern randomized trials of conservative versus liberal transfusion policy, were used. Anemia is compensated and tolerated in most critically ill patients as long as oxygen delivery is at least twice oxygen consumption. There are risks to blood transfusion which can be minimized by blood banking practice. The availability of cultured red cells may allow correction of anemia without significant risk. The benefit of transfusion in anemia must be weighted against the risk in any specific patient. Conclusion and Recommendation: In a criticially ill patient, anemia should be managed to avoid oxygen supply dependency (oxygen delivery less than twice comsumption) and to maintain moderate oxygen delivery reserve (DO2/VO2 > 3).
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Affiliation(s)
- Elena Spinelli
- University of Michigan ECLS Laboratory, Ann Arbor, MI, USA
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Dyson A, Ekbal N, Stotz M, Barnes S, Carré J, Tully S, Henderson S, Barrett L, Singer M. Component reductions in oxygen delivery generate variable haemodynamic and stress hormone responses. Br J Anaesth 2014; 113:708-16. [PMID: 24852502 DOI: 10.1093/bja/aeu089] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND In clinical practice, global oxygen delivery (DO2) is often considered as a whole; however pathological and adaptive responses after a decrease in individual constituents of the DO2 equation (cardiac output, haemoglobin, oxyhaemoglobin saturation) are likely to be diverse. We hypothesized that an equivalent decrease in DO2 after reductions in each separate component of the equation would result in different haemodynamic, tissue oxygenation, and stress hormonal responses. METHODS Anaesthetized, fluid-resuscitated male Wistar rats were subjected to circulatory, anaemic, or hypoxic hypoxia (by haemorrhage, isovolaemic haemodilution, and breathing a hypoxic gas mix, respectively), produced either rapidly over 5 min or graded over 30 min, to a targeted 50% decrease in global oxygen delivery. Sham-operated animals acted as controls. Measurements were made of haemodynamics, skeletal muscle tissue oxygen tension, blood gas analysis, and circulating stress hormone levels. RESULTS Whereas haemorrhage generated the largest decrease in cardiac output, and the greatest stress hormone response, haemodilution had the most marked effect on arterial pressure. In contrast, rapid hypoxaemia produced a minor impact on global haemodynamics yet induced the greatest decrease in regional oxygenation. A greater degree of hyperlactataemia was observed with graded insults compared with those administered rapidly. CONCLUSIONS Decreasing global oxygen delivery, achieved by targeted reductions in its separate components, induces varying circulatory, tissue oxygen tension, and stress hormone responses. We conclude that not all oxygen delivery is the same; this disparity should be emphasized in classical teaching and re-evaluated in patient management.
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Affiliation(s)
- A Dyson
- Bloomsbury Institute of Intensive Care Medicine, Division of Medicine, University College London, London, UK
| | - N Ekbal
- Bloomsbury Institute of Intensive Care Medicine, Division of Medicine, University College London, London, UK
| | - M Stotz
- Bloomsbury Institute of Intensive Care Medicine, Division of Medicine, University College London, London, UK Centre for Perioperative Medicine and Critical Care Research, Imperial College Healthcare NHS Trust, St Mary's Hospital, London, UK
| | - S Barnes
- Bloomsbury Institute of Intensive Care Medicine, Division of Medicine, University College London, London, UK
| | - J Carré
- Bloomsbury Institute of Intensive Care Medicine, Division of Medicine, University College London, London, UK
| | - S Tully
- Bloomsbury Institute of Intensive Care Medicine, Division of Medicine, University College London, London, UK
| | - S Henderson
- Bloomsbury Institute of Intensive Care Medicine, Division of Medicine, University College London, London, UK
| | - L Barrett
- Bloomsbury Institute of Intensive Care Medicine, Division of Medicine, University College London, London, UK
| | - M Singer
- Bloomsbury Institute of Intensive Care Medicine, Division of Medicine, University College London, London, UK
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Wu D, Russano K, Kouz I, Abraham WM. NHE1 inhibition improves tissue perfusion and resuscitation outcome after severe hemorrhage. J Surg Res 2013; 181:e75-81. [DOI: 10.1016/j.jss.2012.07.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Revised: 07/05/2012] [Accepted: 07/11/2012] [Indexed: 11/25/2022]
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Krimins RA, Ko JC, Weil AB, Payton ME, Constable PD. Hemodynamic effects in dogs after intramuscular administration of a combination of dexmedetomidine-butorphanol-tiletamine-zolazepam or dexmedetomidine-butorphanol-ketamine. Am J Vet Res 2012; 73:1363-70. [DOI: 10.2460/ajvr.73.9.1363] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Holahan ML, Brown AJ, Drobatz KJ. The association of blood lactate concentration with outcome in dogs with idiopathic immune-mediated hemolytic anemia: 173 cases (2003-2006). J Vet Emerg Crit Care (San Antonio) 2011; 20:413-20. [PMID: 20731807 DOI: 10.1111/j.1476-4431.2010.00551.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
OBJECTIVE To determine the association of blood lactate with outcome and response to transfusion therapy in dogs with idiopathic immune-mediated hemolytic anemia (IMHA). DESIGN Retrospective study. SETTING Urban veterinary small animal emergency hospital. ANIMALS One hundred and seventy-three client-owned dogs with IMHA. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Serial blood lactate concentration, therapeutic interventions, and outcome were recorded. Nonsurvivors were defined as those that died or were euthanized. One hundred and thirty-three dogs (77%) survived, 35 (20%) were euthanized, and 5 (3%) died. One hundred forty-five dogs (84%; 145/173) had a lactate concentration above the laboratory reference interval [0.46-2.31 mmol/L] on presentation. Blood lactate at presentation was higher in the nonsurvivors (median 4.8 mmol/L; 0.5-13.6) compared with survivors (median 2.9 mmol/L; 0.3-13.2) (P<0.01). All dogs presenting with hyperlactatemia that normalized (<2.0 mmol/L) within 6 hours of admission survived, whereas, 71% of dogs that had a persistent hyperlactatemia at 6 hours survived (P=0.034). Lactate was positively correlated with age, BUN, and alkaline phosphatase, and inversely correlated with PCV. Receiver operating curve analysis for lactate concentration at admission as a test for outcome had an area under the curve of 0.69 with an optimal lactate cutoff concentration of 4.4 mmol/L correctly predicting outcome 73% of the time (sensitivity 60%, specificity 77%). CONCLUSIONS Lactate concentration at presentation was significantly higher in nonsurvivors than survivors. Lactate was significantly correlated with previously reported outcome variables but lactate concentration at admission, as a predictor for outcome was less than optimal. However, serial lactate concentration measurements may be more predictive as patients with persistent hyperlactatemia 6 hours after admission were less likely to survive. Prospective studies evaluating serial lactate concentration while controlling for other variables may provide further insight into lactate measurement as a prognostic indicator in animals with IMHA.
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Affiliation(s)
- Melissa L Holahan
- Section of Critical Care, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Pachtinger GE, Drobatz K. Assessment and treatment of hypovolemic states. Vet Clin North Am Small Anim Pract 2008; 38:629-43, xii. [PMID: 18402887 DOI: 10.1016/j.cvsm.2008.01.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Hypovolemia and hypoperfusion are common life-threatening problems in animals presented to the emergency veterinarian. Assessment of physical findings and rapid recognition and treatment of abnormal tissue perfusion are crucial in optimizing outcome. The clinician should be familiar with the disease being treated and the types of fluids that are available. Development of a fluid therapy plan to correct life-threatening abnormalities and patient monitoring during treatment play an important role in patient outcome.
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Affiliation(s)
- Garret E Pachtinger
- Section of Critical Care, Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, 3900 Delancey Street, Philadelphia, PA 19104, USA.
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Van der Linden PJ, De Hert SG, Belisle S, Sahar G, Deltell A, Bekkrar Y, Blauwaert M, Vincent JL. Critical oxygen delivery during cardiopulmonary bypass in dogs. Eur J Anaesthesiol 2006; 23:10-6. [PMID: 16390559 DOI: 10.1017/s0265021505001699] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/18/2005] [Indexed: 11/05/2022]
Abstract
BACKGROUND AND OBJECTIVE To determine the minimal oxygen delivery and pump flow that can maintain systemic oxygen uptake during normothermic (37 degrees C) pulsatile and non-pulsatile cardiopulmonary bypass in dogs. METHODS Eighteen anaesthetized dogs were randomly assigned to receive either non-pulsatile (Group C; n = 9) or pulsatile bypass flow (Group P; n = 9). Oxygen delivery was reduced by a progressive decrease in pump flow, while arterial oxygen content was maintained constant. In each animal, critical oxygen delivery was determined from plots of oxygen uptake vs. oxygen delivery and from plots of blood lactate vs. oxygen delivery using a least sum of squares technique. Critical pump flow was determined from plots of lactate vs. pump flow. RESULTS At the critical point, oxygen delivery obtained from oxygen uptake was 7.7 +/- 1.1 mL min(-1) kg(-1) in Group C and 6.8 +/- 1.8 mL min(-1) kg(-1) in Group P (n.s.). These values were similar to those obtained from lactate measurements (Group C: 7.8 +/- 1.6 mL min(-1) kg(-1); Group P: 7.6 +/- 2.0 mL min(-1) kg(-1)). Critical pump flows determined from lactate measurements were 55.6 +/- 13.8 mL min(-1) kg(-1) in Group C and 60.8 +/- 13.9 mL min(-1) kg(-1) in Group P (n.s.). CONCLUSIONS Oxygen delivery values greater than 7-8 mL min(-1) kg(-1) were required to maintain oxygen uptake during normothermic cardiopulmonary bypass with either pulsatile or non-pulsatile blood flow. Elevation of blood lactate levels during bypass helps to identify inadequate tissue oxygen delivery related to insufficient pump flow.
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Affiliation(s)
- P J Van der Linden
- Charleroi University Hospital, Department of Cardiac Anaesthesia (now CHU-Brugmann, Department of Anaesthesiology, Brussels), Charleroi, Belgium
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Haskins SC, Pascoe PJ, Ilkiw JE, Fudge M, Hopper K, Aldrich J. The effect of moderate hypovolemia on cardiopulmonary function in dogs. J Vet Emerg Crit Care (San Antonio) 2005. [DOI: 10.1111/j.1476-4431.2005.00129.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Boag AK, Hughes D. Assessment and treatment of perfusion abnormalities in the emergency patient. Vet Clin North Am Small Anim Pract 2005; 35:319-42. [PMID: 15698913 DOI: 10.1016/j.cvsm.2004.10.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Many patients presented to the emergency veterinarian are suffering from global or local tissue hypoperfusion. Global or systemic hypoperfusion can occur secondary to a reduction in the effective circulating intravascular volume (hypovolemic shock) or reduced ability of the heart to pump blood around the body secondary to reduced cardiac function (cardiogenic shock),obstruction to blood flow (obstructive shock), or maldistribution of the circulating intravascular volume (distributive shock). Initial assessment involving physical examination supplemented by measurement of hemodynamic and metabolic parameters allows the clinician to recognize and treat patients with severe global hypoperfusion. Use of techniques like sublingual capnometry and measurement of central venous oxygen saturation may aid recognition and evaluation of early hypoperfusion. Treatment decisions are made based on an assessment of the severity of the hypoperfusion and its probable underlying cause. Early effective treatment of hypoperfusion is likely to lead to a better outcome for the patient.
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Affiliation(s)
- Amanda K Boag
- Queen Mother Hospital, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire AL9 7TA, United Kingdom.
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20
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Vincent JL, De Backer D. Oxygen transport-the oxygen delivery controversy. Intensive Care Med 2004; 30:1990-6. [PMID: 15258731 DOI: 10.1007/s00134-004-2384-4] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2003] [Accepted: 06/24/2004] [Indexed: 12/22/2022]
Affiliation(s)
- Jean-Louis Vincent
- Department of Intensive Care, Erasme University Hospital, Free University of Brussels, Route de Lennik 808, 1070 Brussels, Belgium.
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21
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Smithline HA, Ward KR, Chiulli DA, Blake HC, Rivers EP. Whole body oxygen consumption and critical oxygen delivery in response to prolonged and severe carbon monoxide poisoning. Resuscitation 2003; 56:97-104. [PMID: 12505745 DOI: 10.1016/s0300-9572(02)00272-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Carbon monoxide (CO) poisoning remains the leading cause of death by poisoning in the world. One of the major proposed mechanisms for CO toxicity is the binding of CO to cytochrome oxidase and interference with cellular oxygen utilization but evidence for this is inconclusive. AIM OF STUDY This study examined the effects of prolonged CO exposure on the dynamics of whole body oxygen consumption (VO(2)) and oxygen delivery (DO(2)) in an attempt to observe if CO exposure results in a defect of oxygen utilization defect as determined by a reduction in VO(2) during the course of poisoning prior to reaching the point where VO(2) is directly dependent on DO(2). This critical level of DO(2) (DO(2)crit) produced by CO poisoning was compared to historical values produced by other insults, which decrease global body DO(2). METHODS Five small dogs were ventilated for 2 h with 0.25% CO and room air followed by 0.5% CO until death. Cardiac index (Q), DO(2), VO(2), oxygen extraction ratio (OER), and systemic lactate were measured every 15 min until death. RESULTS Carboxyhemoglobin (COHb) levels increased linearly over 2.5 h to values above 80% until death. VO(2) remained constant and not significantly different from baseline below a COHb of 80%. At COHb levels above 80%, VO(2) precipitously dropped. Similarly lactate levels were not significantly elevated from baseline until VO(2) dropped. DO(2) decreased by 78% (from 23+/-6 ml/kg/min to 5+/-4 ml/kg/min) over time despite an increase in Q by 58% until levels of COHb were above 80%. OER increased from 19+/-5% to 50+/-11% until death. The calculated DO(2)crit was 10.7+/-4 ml/min/kg, which is not significantly different from values ranging from 7 to 13 ml/min/kg reported in the literature due to other insults, which reduce DO(2). CONCLUSION In this canine model of prolonged CO exposure, no gradual reduction in VO(2) or increase in systemic lactate prior to reaching DO(2)crit was noted. In addition, CO exposure does not appear to change the DO(2)crit. The combination of these findings does not support the theory that CO produces a whole body intracellular defect in oxygen utilization.
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Affiliation(s)
- Howard A Smithline
- Baystate Medical Center, Department of Emergency Medicine, Baystate, MA, USA
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22
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Chiara O, Pelosi P, Segala M, Turconi MG, Brazzi L, Bottino N, Taccone P, Zambelli M, Tiberio G, Boswell S, Scalea TM. Mesenteric and renal oxygen transport during hemorrhage and reperfusion: evaluation of optimal goals for resuscitation. THE JOURNAL OF TRAUMA 2001; 51:356-62. [PMID: 11493800 DOI: 10.1097/00005373-200108000-00023] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Changes in flow to the gut and the kidney during hemorrhage and resuscitation contribute to organ dysfunction and outcome. We evaluated regional and splanchnic oxygen (O2) flow distribution and calculated oxygen supply distribution during hemorrhage and reperfusion and compared them with global measures. METHODS Seven anesthetized pigs were instrumented to evaluate global hemodynamics, visceral blood flow, and oxygen transport. Tonometric pH probes were positioned in the stomach and jejunum. Animals were bled to 45 mm Hg for 1 hour. Crystalloids and blood were infused during the following 2 hours to normalize blood pressure, heart rate, urine output, and hemo- globin. RESULTS During hemorrhage, mesenteric flow and O2 consumption were significantly decreased, whereas systemic consumption remained normal. Renal flow was reduced, but renal O2 consumption remained normal. After resuscitation, despite normal hemodynamics, neither systemic, mesenteric, nor renal O2 delivery returned to baseline. Lactate remained significantly increased. Arterial pH, base excess, and gastric and jejunal pH were all decreased. CONCLUSION During hemorrhage, the gut is more prone than other regions to O2 consumption supply dependency. After resuscitation, standard clinical parameters do not detect residual O2 debt. Lactate, arterial pH, base excess, and intramucosal gut pH are all markers of residual tissue hypoperfusion.
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Affiliation(s)
- O Chiara
- Istituto di Chirurgia d'Urgenza, Universita' degli Studi di Milano, Ospedale Maggiore IRCCS, Milano, Italy
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23
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Widness JA, Lowe LS, Bell EF, Burmeister LF, Mock DM, Kistard JA, Bard H. Adaptive responses during anemia and its correction in lambs. J Appl Physiol (1985) 2000; 88:1397-406. [PMID: 10749835 DOI: 10.1152/jappl.2000.88.4.1397] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
There is limited information available on which to base decisions regarding red blood cell (RBC) transfusion treatment in anemic newborn infants. Using a conscious newborn lamb model of progressive anemia, we sought to identify accessible metabolic and cardiovascular measures of hypoxia that might provide guidance in the management of anemic infants. We hypothesized that severe phlebotomy-induced isovolemic anemia and its reversal after RBC transfusion result in a defined pattern of adaptive responses. Anemia was produced over 2 days by serial phlebotomy (with plasma replacement) to Hb levels of 30-40 g/l. During the ensuing 2 days, Hb was restored to pretransfusion baseline levels by repeated RBC transfusion. Area-under-the-curve methodology was utilized for defining the Hb level at which individual study variables demonstrated significant change. Significant reciprocal changes (P < 0.05) of equivalent magnitude were observed during the phlebotomy and transfusion phases for cardiac output, plasma erythropoietin (Epo) concentration, oxygen extraction ratio, oxygen delivery, venous oxygen saturation, and blood lactate concentration. No significant change was observed in resting oxygen consumption. Cardiac output and plasma Epo concentration increased at Hb levels <75 g/l, oxygen delivery and oxygen extraction ratio decreased at Hb levels <60 g/l, and venous oxygen saturation decreased and blood lactate concentration increased at Hb levels <55 g/l. We speculate that plasma Epo and blood lactate concentrations may be useful measures of clinically significant anemia in infants and may indicate when an infant might benefit from a RBC transfusion.
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Affiliation(s)
- J A Widness
- Department of Pediatrics, College of Medicine, The University of Iowa, Iowa City 52242, USA.
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24
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Yang S, Zhou M, Koo DJ, Chaudry IH, Wang P. Pentoxifylline prevents the transition from the hyperdynamic to hypodynamic response during sepsis. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:H1036-44. [PMID: 10484426 DOI: 10.1152/ajpheart.1999.277.3.h1036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The cardiovascular response to sepsis includes an early, hyperdynamic phase followed by a late, hypodynamic phase. Although administration of pentoxifylline (PTX) produces beneficial effects in sepsis, it remains unknown whether this agent prevents the transition from the hyperdynamic to the hypodynamic response during the progression of sepsis. To study this, male adult rats were subjected to polymicrobial sepsis by cecal ligation and puncture (CLP). At 1 h after CLP, PTX (50 mg/kg body wt) or vehicle was infused intravenously over 30 min. At 20 h after CLP (i.e., the late stage of sepsis), cardiac output and organ blood flow were measured by radioactive microspheres. Systemic and regional (i.e., hepatic, intestinal, and renal) oxygen delivery (DO2) and oxygen consumption (VO2) were determined. Moreover, plasma levels of lactate and alanine aminotransferase (ALT) were measured, and histological examinations were performed. In additional animals, the necrotic cecum was excised at 20 h after CLP, and mortality was monitored for 10 days thereafter. The results indicate that cardiac output, organ blood flow, and systemic and regional DO2 decreased by 36-65% (P < 0.05) at 20 h after CLP. Administration of PTX early after the onset of sepsis, however, prevented reduction in measured hemodynamic parameters and increased systemic and regional DO2 and VO(2) by 50-264% (P < 0.05). The elevated levels of lactate (by 173%, P < 0.05) and ALT (by 718%, P < 0.05), as well as the morphological alterations in the liver, small intestine, and kidneys during sepsis were attenuated by PTX treatment. In addition, PTX treatment decreased the mortality rate from 50 to 0% (P < 0.05) after CLP and cecal excision. Because PTX prevents the occurrence of hypodynamic sepsis, this agent appears to be a useful adjunct for maintaining hemodynamic stability and preventing lethality from sepsis.
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Affiliation(s)
- S Yang
- Center for Surgical Research and Department of Surgery, Brown University School of Medicine and Rhode Island Hospital, Providence, Rhode Island 02903, USA
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Schou H, Kongstad L, Perez de Sa V, Werner O, Larsson A. Uncompensated Blood Loss Is Not Tolerated During Acute Normovolemic Hemodilution in Anesthetized Pigs. Anesth Analg 1998. [DOI: 10.1213/00000539-199810000-00009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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26
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Schou H, Kongstad L, Perez de Sá V, Werner O, Larsson A. Uncompensated blood loss is not tolerated during acute normovolemic hemodilution in anesthetized pigs. Anesth Analg 1998; 87:786-94. [PMID: 9768771 DOI: 10.1097/00000539-199810000-00009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
UNLABELLED Clinically, hemodilution to a hematocrit of 9% has been studied, but the effects of hypovolemia during this degree of hemodilution have not been elucidated. We studied the response to blood loss during extreme hemodilution and evaluated indicators of hypovolemia. Systemic and myocardial hemodynamics, oxygen transport, and blood lactate concentrations were measured in 12 anesthetized pigs exposed to a graded blood loss of 10, 20, 30, and 40 mL/kg. Six animals were hemodiluted (hematocrit 10.8% +/- 1.4%, mean +/- SD), and six animals served as controls (hematocrit 34.6% +/- 1.5%). Hemodilution decreased systemic oxygen delivery to 9.5 +/- 0.6 mL x kg(-1) x min(-1) (controls 21.7 +/- 3.9 mL x kg(-1) x min(-1)) (P < 0.01) despite a 31% increase in cardiac output. Systemic oxygen uptake was unchanged. Arterial lactate increased to 3.3 +/- 1.1 mM/L (controls 1.6 +/- 0.6 mM/L) (P < 0.05), and mixed venous oxygen saturation (SvO2) decreased to 38.2% + 4.8% (controls 68.6% +/- 2.9%) (P < 0.01). At a blood loss of 10 mL/kg, cardiac output continued to be greater in the hemodiluted animals (P < 0.01). Arterial blood pressure decreased to 61 +/- 8 mmHg (controls 84 +/- 18 mm Hg) (P < 0.05), whereas heart rate was unchanged. Systemic oxygen delivery decreased to 8.8 +/- 1.2 mL x kg(-1) x min(-1) (controls 14.1 +/- 2.5 mL x kg(-1) x min(-1)) (P < 0.01). Systemic oxygen uptake was maintained by a further increase in oxygen extraction, and SvO2 decreased to 29.7% +/- 7.3%, compared with 55.3% +/- 9.0% in controls (P < 0.01). Arterial lactate increased to 4.9 +/- 1.4 mM/L (controls 1.8 +/- 0.8 mM/L) (P < 0.01). Myocardial oxygen delivery and lactate uptake were unchanged. When the blood loss equaled 30 mL/kg, myocardial lactate production occurred, and two hemodiluted animals died of circulatory failure. Central venous and capillary wedge pressures changed minimally during the blood loss and did not differ between groups. We conclude that a decrease in arterial blood pressure and SvO2 were early signs of hypovolemia during hemodilution, whereas central venous pressure and pulmonary capillary wedge pressure were insensitive indicators. IMPLICATIONS Anesthetized pigs with extremely low hemoglobin levels (one third of normal) showed poor tolerance to blood loss >10 mL/kg. A decreasing arterial blood pressure, a decreasing oxygen saturation in the venous blood, and an increase in arterial blood lactate concentration were useful indicators of blood loss.
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Affiliation(s)
- H Schou
- Department of Anesthesia and Intensive Care, University Hospital, Lund, Sweden
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27
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Licker M, Schweizer A, Hohn L, Morel DR. Haemodynamic and metabolic changes induced by repeated episodes of hypoxia in pigs. Acta Anaesthesiol Scand 1998; 42:957-65. [PMID: 9773141 DOI: 10.1111/j.1399-6576.1998.tb05356.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Repeated hypoxia and surgical trauma trigger a potent neuroendocrine response and their association is thought to play a pivotal role in the pathogenesis of multi-organ dysfunction. We investigated the cardiovascular and metabolic responses to repeated acute hypoxia in anaesthetised and surgically instrumented pigs. METHODS Under ketamine-midazolam anaesthesia, 15 pigs were surgically instrumented for measurements of cardiac output, vascular pressures and organ blood flows. Lactate production and O2 uptake were determined in the brain, liver, kidney and intestine. Ten animals were subjected to two 12-min periods of ventilatory hypoxia (FIO2 = 7%) followed by re-oxygenation and 5 animals underwent 120-min normoxic ventilation (Control group). RESULTS Both hypoxic challenges produced a comparable release of catecholamines that was associated with increased cardiac output and redistribution of blood flow away from the intestinal and renal areas towards the brain and the liver; O2 uptake was markedly reduced in the intestine (-56 +/- 10%, P < 0.05) and least affected in the brain and the kidney (-19 +/- 12% and -23 +/- 21%, respectively). During the second hypoxic test, lethal cardiovascular depression occurred in 5 animals; these non-survivors demonstrated impaired hyperdynamic response and incomplete recovery of intestinal O2 uptake during the first hypoxia/reoxygenation test. In the Control group, normoxic ventilation was not associated with significant haemodynamic and metabolic changes. CONCLUSION Intraoperative hypoxia causes marked heterogeneity in organ blood flow and metabolism. The inability to develop a hyperdynamic cardiovascular response during a first hypoxic event, as well as a persistent intestinal O2 debt following re-oxygenation, predict the occurrence of death during the second hypoxic insult.
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Affiliation(s)
- M Licker
- Divisions of Anaesthesiological Investigations, University Hospital of Geneva, Switzerland
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Rich PB, Awad SS, Kolla S, Annich G, Schreiner RJ, Hirschl RB, Bartlett RH. An approach to the treatment of severe adult respiratory failure. J Crit Care 1998; 13:26-36. [PMID: 9556124 DOI: 10.1016/s0883-9441(98)90026-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES The purpose of this article is to evaluate outcome in adult patients with severe respiratory failure managed with an approach using (1) limitation of end inspiratory pressure, (2) inverse ratio ventilation, (3) titration of PEEP by SvO2, (4) intermittent prone positioning, (5) limitation of FiO2, (6) diuresis, (7) transfusion, and (8) extracorporeal life support (ECLS) if patients failed to respond. PATIENTS AND METHODS This study was designed as a retrospective review in the intensive care unit of a tertiary referral hospital. One-hundred forty-one consecutive patients with hypoxic (n = 135) or hypercarbic (n = 6) respiratory failure referred for consideration of ECLS between 1990 and 1996. Overall, initial PaO2/FiO2 (P/F) ratio was 75+/-5 (median = 66). RESULTS Lung recovery occurred in 67% of patients and 62% survived. Forty-one patients improved without ECLS (83% survived); 100 did not and were supported with ECLS (54% survived). Survival was greater in patients cannulated within 12 hours of arrival (59%) compared with those cannulated after 12 hours (40%, P < .05). Multiple logistic regression identified age, duration of mechanical ventilation before transfer, four or more dysfunctional organs, and the requirement for ECLS as independent predictors of mortality. CONCLUSIONS An approach that emphasizes lung protection and early implementation of extracorporeal life support is associated with high rates of survival in patients with severe respiratory failure.
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Affiliation(s)
- P B Rich
- Department of Surgery, University of Michigan Medical Center, Ann Arbor 48109-0331, USA
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Ransbaek F, Hansen SB, Austin EH, Santamore WP. Effects of positive pressure ventilation and inspired oxygen on pulmonary vascular resistance and tissue oxygen delivery in neonatal pigs. Cardiol Young 1998; 8:71-8. [PMID: 9680274 DOI: 10.1017/s1047951100004662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Management of pulmonary vascular resistance in neonates with congenital heart disease is important for stabilization before and after surgical interventions. Thus, we determined which combination of positive end-expiratory pressure ventilation and fraction of oxygen in the inspired air increases pulmonary vascular resistance without compromising delivery of oxygen to the tissue. Eight piglets were anesthetized, intubated and ventilated. Pulmonary flow and pulmonary arterial and left atrial pressures were monitored continuously. At all levels of inspired oxygen (1.00, 0.21 and 0.15), ventilation at a pressure of 15 cm of water increased pulmonary vascular resistance. At all levels of positive pressure ventilation, a fraction of 0.15 of inspired oxygen increased pulmonary vascular resistance. The combination of a ventilatory pressure of 15 cm of water and inspired oxygen of 1.00, or ventilatory pressure at 5 cm of water and oxygen delivery of 0.15, produced similar changes in pulmonary vascular resistance (19.1 +/- 2.8 vs. 20.0 +/- 3.8 mmHg/(L/min)) and cardiac output (0.78 +/- 0.07 vs. 0.93 +/- 0.10 L/min) but, the higher level of positive pressure plus 1.00 inspired oxygen gave a significantly higher arterial oxygen saturation (0.99 +/- 0.03 vs. 0.72 +/- 0.19%) and delivery of oxygen to the tissues (13.7 +/- 2.9 vs. 7.4 +/- 1.5 ml O2/min, p < 0.05). Thus, both high positive pressure ventilation and hypoxia increase pulmonary vascular resistance. Only high pressure ventilation plus high concentrations of inspired oxygen, however, increased pulmonary vascular resistance without compromising delivery of oxygen, suggesting that this combination is a superior means of increasing pulmonary vascular resistance.
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Affiliation(s)
- F Ransbaek
- Department of Surgery, University of Louisville, KY 40292, USA
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Schou H, Perez de Sá V, Roscher R, Larsson A. Nitrous oxide reduces inspired oxygen fraction but does not compromise circulation and oxygenation during hemodilution in pigs. Acta Anaesthesiol Scand 1997; 41:923-30. [PMID: 9265938 DOI: 10.1111/j.1399-6576.1997.tb04810.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND The use of nitrous oxide (N2O) during hemodilution has been questioned. Nitrous oxide reduces the inspired oxygen fraction (F1O2), depresses myocardial function and may reduce cardiac output (CO) and systemic oxygen delivery (DO2SY). The aim of this study was to evaluate the importance of the effects of nitrous oxide on systemic and myocardial circulation and oxygenation during extreme, acute, normovolemic hemodilution. METHODS Ten midazolam-fentanyl-pancuronium anesthetized pigs were exposed to 65% N2O before and after extreme isovolemic hemodilution (hematocrit 33 +/- 1% and 10 +/- 1%, respectively). Systemic and myocardial hemodynamics, oxygen delivery and consumption and blood lactate were measured before (at F1O2 1.0 and 0.35) and during N2O exposure. RESULTS Hemodilution caused an increase in CO from 137 +/- 43 to 229 +/- 32 ml.kg-1.min-1 (P < 0.01), a decrease in systemic vascular resistance (from 42 +/- 14 to 20 +/- 4 mmHg.L-1.min-1, P < 0.05), a decrease in mean arterial blood pressure (from 119 +/- 19 to 100 +/- 26 mmHg, P < 0.05) and a decrease in DO2SY from 21.1 +/- 6.9 to 13.7 +/- 2.1 ml.kg-1.min-1 (P < 0.01). Cardiac venous blood flow increased by 135% (P < 0.01) and cardiac venous saturation from 25 +/- 6 to 41 +/- 5% (P < 0.05). After hemodilution, changing F1O2 from 1.0 to 0.35 reduced arterial blood oxygen content from 59.4 +/- 3.7 to 52.3 +/- 5.1 ml.L-1 (P < 0.01), mixed venous saturation (SvO2) from 75 +/- 9 to 47 +/- 7% (P < 0.05) and DO2SY from 13.7 +/- 2.1 to 11.9 +/- 2.3 ml.kg-1.min-1 (P < 0.05). Dissolved oxygen at F1O2 = 1.0 and F1O2 = 0.35 constituted 25.4 +/- 3.1% and 10.1 +/- 1.5%, respectively, of systemic oxygen delivery after hemodilution, compared with 10.7 +/- 1.2% and 3.9 +/- 0.5% before hemodilution (P < 0.01). Left ventricular oxygen delivery and consumption were unchanged. Exposure to N2O did not affect mean arterial blood pressure or systemic vascular resistance before or after hemodilution. After hemodilution during N2O-exposure, CO and DO2SY decreased by 9% (P < 0.01 and P < 0.05, respectively), but no changes in SvO2, systemic oxygen uptake or arterial lactate were observed. The effect of N2O on myocardial oxygenation was similar before and after hemodilution; cardiac venous blood flow, left ventricular oxygen delivery and uptake decreased, but no animals showed left ventricular lactate production. CONCLUSION Nitrous oxide did not compromise systemic and myocardial circulation and oxygenation during acute normovolemic hemodilution in pigs. Possible adverse effects from the use of nitrous oxide during hemodilution seem to be related to a reduced F1O2, reducing the safety margin for systemic oxygen delivery.
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Affiliation(s)
- H Schou
- Department of Anesthesia and Intensive Care, University Hospital Lund, Sweden
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Schou H, Perez de Sá V, Larsson A, Roscher R, Kongstad L, Werner O. Hemodilution significantly decreases tolerance to isoflurane-induced cardiovascular depression. Acta Anaesthesiol Scand 1997; 41:218-28. [PMID: 9062603 DOI: 10.1111/j.1399-6576.1997.tb04669.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Hemodilution is used to reduce the need for allogenic blood transfusion. The aim of this study was to evaluate to what extent acute extreme normovolemic hemodilution affects the circulatory response to isoflurane. METHODS Ten midazolam-fentanyl-pancuronium anesthetized pigs were exposed to isoflurane at end-tidal concentrations of 0, 0.5, 1.0, 1.5 and 2%, before and after extreme normovolemic hemodilution (hematocrit 33 +/- 3% and 11 +/- 1%, respectively). Systemic and myocardial hemodynamics and oxygen delivery and consumption were measured. RESULTS At zero end-tidal isoflurane concentration, hemodilution caused an increase in cardiac output (from 157 +/- 12 to 227 +/- 39 ml kg min-1, P < 0.01) a decrease in systemic vascular resistance (from 39 +/- 7 to 18 +/- 5 mmHg.L-1.min-1, P < 0.01) a decrease in mean arterial blood pressure (MAP) (from 130 +/- 13 to 91 +/- 13 mmHg, P < 0.01) and a decrease in systemic oxygen delivery (from 23.1 +/- 2.7 to 11.8 +/- 1.7 ml.kg-1.min-1, P < 0.01). When the end-tidal isoflurane concentration was increased from 0 to 2% after hemodilution, cardiac output decreased by 86 +/- 37 ml.kg-1.min-1, as compared with 36 +/- 20 ml.kg-1.min-1 (P < 0.01) before hemodilution. Likewise, systemic vascular resistance decreased with increasing isoflurane concentrations; at 2%, the decrease was 7 +/- 4 mmHg.L-1.min-1 after hemodilution and 18 +/- 5 mmHg.L-1.min-1 before hemodilution (P < 0.01). At an end-tidal isoflurane concentration of 2%, MAP had decreased to 43 +/- 6 mmHg after hemodilution, and to 61 +/- 15 mmHg before hemodilution (P < 0.01). After hemodilution, isoflurane concentrations above 1% decreased systemic oxygen delivery enough to cause delivery-dependent oxygen consumption and hyperlactemia; and at 2% isoflurane, myocardial blood flow became insufficient, as indicated by myocardial lactate production. CONCLUSIONS isoflurane-induced cardiovascular depression had adverse effects on cardiac output and oxygen delivery during extreme hemodilution because: 1) The vasodilatory effect of isoflurane was insufficient to compensate for the myocardial depression, and also contributed to a critically low arterial blood pressure; 2) A decrease in cardiac output produced delivery-dependent oxygen consumption and hyperlactemia; and 3) A decrease in myocardial blood flow caused myocardial ischemia which may have exacerbated the myocardial depression.
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Affiliation(s)
- H Schou
- Department of Anesthesia and Intensive Care, University Hospital, Lund, Sweden
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