Effect of forage type, season, and ripening time on selected quality properties of sheep milk cheese.

The aim of this research was to study changes in the microbial populations, free AA profile, biogenic amine content, and sensory characteristics of ripened cheeses (100 and 180 d) produced in different seasons (summer, autumn, winter, and spring) from pasteurized sheep milk from 8 commercial flocks fed hay or silage diets. Twenty-one individual AA and 6 biogenic amines were determined by ultra-high performance liquid chromatography. Type of conserved forage for sheep feeding did not affect the variables studied, which is of great interest because hay and silage are low-cost ingredients for sheep feeding. Proteolysis led total free AA concentrations ranging between 35,179.26 and 138,063.71 mg/kg of cheese at 180 d of ripening. γ-Aminobutyric acid, which has been associated with beneficial effects on human health, was the second most abundant AA in all cheese samples, accounting for 15% of total free AA. Spring cheeses showed 2-fold higher concentrations of γ-aminobutyric acid than summer and autumn cheeses at the end of ripening. Overall, spring, winter, and autumn cheeses had lower average concentration of biogenic amines (431.99 mg/kg of cheese) than summer cheeses (825.70 mg/kg of cheese) as well as better sensory characteristics. Therefore, this study could provide the dairy industry with useful information for producing cheeses with valuable nutritional and sensory quality for consumers.

Effect of forage type in the ovine diet on the nutritional profile of sheep milk cheese fat.

The high nutritional value of sheep milk can be advantageous in the manufacture of cheese, and fat plays an important role in sheep cheese properties. The aim of this study was to investigate the effect of feeding common hay or silage diets used in commercial farms on the nutritional value of sheep cheese fat. We also monitored the effect of cheese ripening period on the fatty acid profile. Cheeses were produced from milk of sheep fed hay and silage diets from 8 farms, on 4 separate occasions (February, May, August, and November) over a 1-yr period. Eighty-four individual fatty acids were determined and identified by gas chromatography. Ripening time (100 and 180 d) significantly reduced moisture, acidity, and water activity of cheeses but did not affect the fatty acid content. However, hay feeding, compared with silage feeding, led to cheeses with 1.5- and 1.3-fold higher contents of vaccenic acid and conjugated linoleic acid, without detrimental changes in saturated and n-3 (omega-3) fatty acid composition. Hay forages could be a low-cost alternative for producing cheese with a fatty acid profile suitable for human health, which is an aspect of great interest to the food industry.

CLA-producing adjunct cultures improve the nutritional value of sheep cheese fat.

The influence of the autochthonous CLA-producing Lactobacillus plantarum TAUL 1588 and Lactobacillus casei subsp. casei SS 1644 strains and the ripening time on the fatty acid (FA) content and sensory characteristics of sheep cheese were investigated. Three cheese types with different cultures and the control cheese were produced in duplicate and ripened for 8 months. 86 individual FA were determined by gas chromatography. Ripening time (2, 90, 180 and 240 days) did not have a significant effect (P > .05) on the FA content. However, the presence of both Lactobacillus CLA-producing strains led to a decrease of the saturated FA content and to 1.30, 1.19 and 1.27 times higher levels of vaccenic acid, CLA and omega-3, respectively, when compared to the control cheese. This combination allowed obtaining sheep milk cheeses with a healthier FA content, without appreciable changes on sensory characteristics. This work could be a promising approach to increase the bioactive fatty acid content of cheeses.

Production of sheep milk cheese with high γ-aminobutyric acid and ornithine concentration and with reduced biogenic amines level using autochthonous lactic acid bacteria strains.

Consumer demand for health-promoting foods is generating the need to develop biofunctional dairy products. Lactic acid bacteria are employed in cheese-making and some of them are able to produce beneficial compounds on human health such as γ-aminobutyric acid (GABA) and ornithine but also to synthetize biogenic amines. The aim was to investigate the effect of four selected autochthonous co-cultures on the free amino acid profile, with special emphasis on GABA and ornithine, and on the biogenic amine content of pasteurized sheep milk cheese during ripening. High average concentrations of GABA (1296.75 mg/kg cheese) and ornithine (2355.76 mg/kg cheese) were found in all the cheese batches at 240 days of ripening. Batch 2, manufactured with the co-culture containing autochthonous Lactococcus lactis strains as starter and Lactobacillus plantarum TAUL1588 as adjunct, showed 2.37 fold reduced biogenic amines concentration with respect to the batch 1 made with the starter during the ripening time. The microstructure and microbiological counts of cheeses were affected (P ≤ 0.001) by the ripening time, without appreciating differences (P ≥ 0.05) in the physico-chemical composition between batches. This study could be a good approach to the development of functional sheep milk cheese.

Effect of autochthonous starter cultures on the biogenic amine content of ewe's milk cheese throughout ripening.

Cheese is among the most commonly implicated foods associated with biogenic amines poisoning. The aim of this study was to evaluate the effects of the type of autochthonous starter culture and ripening time on the concentration of biogenic amines (histamine, tyramine, putrescine, cadaverine, tryptamine, ß-phenylethylamine, spermine and spermidine) in cheeses made from pasteurized ewe's milk. 4 cheese batches were made, in duplicate, and ripened for 7 months. The biogenic amines of 40 cheeses were analysed by high performance liquid chromatography. The predominant biogenic amines determined at the end of the ripening time were phenylethylamine, spermine and tryptamine. Together, these accounted for 81% of the total of biogenic amines studied. The type of starter culture used to make the ewe's cheese had a significant effect (p < 0.001) on the content of biogenic amines throughout ripening time. It was lower in the batches made with an autochthonous starter culture made up entirely of Lactococcus lactis subsp. lactis and L. lactis subsp. cremoris or of the same in combination with Lactobacillus plantarum.

Diagnóstico y alternativas terapéuticas en la isquemia miocárdica aguda perioperatoria en cirugía coronaria / Diagnostic and therapeutic alternatives in perioperative acute myocardial ischemia in heart surgery

La isquemia y el infarto posrevascularización quirúrgica son unas complicaciones relativamente frecuentes y pueden conllevar una morbimortalidad elevada. El diagnóstico precoz es fundamental, pero está menos estandarizado y es más complicado que en los pacientes que no reciben cirugía cardíaca, y no existe ningún marcador específico capaz de distinguir entre la isquemia miocárdica en relación con el procedimiento en sí y el daño miocárdico asociado a infarto perioperatorio. Ante la detección de isquemia perioperatoria, se debe proceder de inmediato para instaurar medidas con la intención de limitar el daño miocárdico.Los objetivos de este estudio son los siguientes: 1) revisar los métodos diagnósticos disponibles para la isquemia miocárdica aguda perioperatoria y los criterios de infarto agudo de miocardio perioperatorio; 2) revisar las diferentes opciones terapéuticas existentes, y 3) proponer un algoritmo de tratamiento que contempla la necesidad de realizar un diagnóstico diferencial, el control del vasoespasmo, la implantación de balón de contrapulsación y las posibles estrategias de revascularización (intervención coronaria percutánea o reintervención quirúrgica)(AU)

Ischemia and infarct after surgical revascularization are a relatively frequent complication, with high morbidity and mortality. Early diagnosis is essential. However, this is less standardized and more complicated to diagnose than in patients who have not undergone surgery since there is no specific biomarker that allows the clinician to differentiate between myocardial ischemia due to the procedure itself and myocardial damage due to perioperative infarct.Once detected, perioperative ischemia should be treated immediately in order to limit myocardial damage.The objectives of this study have been 1. To show the diagnostic criteria for perioperative infarct and ischemia. 2. to show the different therapeutic options available. 3. to propose a treatment algorithm that includes the differential diagnosis, how to control vasospasm, implantation of balloon counterpulsation, and the possible revascularization strategies (percutaneous coronary intervention vs reoperation (AU)

[Diagnostic and therapeutic alternatives in perioperative acute myocardial ischemia in heart surgery]. / Diagnóstico y alternativas terapéuticas en la isquemia miocárdica aguda perioperatoria en cirugía coronaria.

Ischemia and infarct after surgical revascularization are a relatively frequent complication, with high morbidity and mortality. Early diagnosis is essential. However, this is less standardized and more complicated to diagnose than in patients who have not undergone surgery since there is no specific biomarker that allows the clinician to differentiate between myocardial ischemia due to the procedure itself and myocardial damage due to perioperative infarct. Once detected, perioperative ischemia should be treated immediately in order to limit myocardial damage. The objectives of this study have been 1. To show the diagnostic criteria for perioperative infarct and ischemia. 2. to show the different therapeutic options available. 3. to propose a treatment algorithm that includes the differential diagnosis, how to control vasospasm, implantation of balloon counterpulsation, and the possible revascularization strategies (percutaneous coronary intervention vs reoperation).

Analgesia con remifentanilo. Réplica / Remifentanil analgesia. Reply

No disponible

Tiempo de respuesta de un sistema de medición de gasto cardíaco continuo por termodilución y saturación venosa mixta en una paciente con asistencia ventricular izquierda total / Responde tiem of a continuous cardiac output measuring system using thermodilution and mixed venous oxygen saturation in a patient with total left ventricular assistance

La monitorización del gasto cardíaco continuo (GCC) por termodilución está disponible en la práctica clínica desde hace unos pocos años. Presentamos el caso de una paciente con disfunción grave del ventrículo izquierdo tras un bypass cardiopulmonar que requirió un dispositivo de asistencia ventricular izquierda (AVI); dado que la paciente presentaba la válvula mitral implantada trombosada, el dispositivo fue una asistencia ventricular "total" del ventrículo asistido. Los tiempos de respuesta real in vivo de los sistemas de monitorización del GCC y la saturación venosa mixta (Sv¯O2) fueron medidos tras aplicar cambios en el flujo de la AVI. Calculamos la correlación entre el GCC y el flujo de la AVI, entre el GCC y la medición de gasto cardíaco en bolo por termodilución tradicional, y entre el GCC y la Sv¯O2. La monitorización continua de la Sv¯O2 y el GCC en pacientes inestables hemodinámicamente permite la detección precoz y el tratamiento de cualquier cambio significativo en el estado hemodinámico (AU)

Neurological complications after cardiopulmonary bypass: An update.

INTRODUCTION: Neurological complications are, at the present time, considered among the most important causes of morbidity and mortality after heart surgery. We evaluated their importance and risk factors. PATIENTS AND METHODS: We retrospectively reviewed 2, 528 consecutive patients who underwent cardiopulmonary bypass in a single center. In each one, we attended to previous vascular risk factors, such as surgical and postoperative events. We considered four categories of neurologic outcome: (1) persistent neurological focal deficits, (2) stupor or coma, (3) temporary neurological focal deficits, and (4) seizures. We carried out univariant and multivariant statistical analysis, looking for predictors of adverse neurologic events. RESULTS: Neurological complications occurred in 76 patients (3%); 36 of them (47%) had persistent neurological focal deficits, 18 (24%) stupor or coma, 18 (24%) temporary neurological focal deficits, and 27 (36%) seizures. Twenty-two patients with cerebral adverse outcomes died (29%), the overall mortality among the 2,528 cases being 5%. Predictors of risk were aortic aneurysm and aortic valve surgery, advanced age, female sex, and the use of intra-aortic balloon pump. A longer hospitalization time was noticed among patients with neurological side effects. DISCUSSION: Neurological complications are common and serious after heart surgery, as we have noticed with this series, the largest up to now, according to our review of the literature. They increase perioperative mortality and hospitalization time. Neurological morbidity and risk factors in our study are similar to those previously published.

Effects of nitric oxide synthase inhibition on the cardiovascular response to low output shock.

OBJECTIVE: To study the role of nitric oxide in the cardiovascular response to a model of a low output syndrome. DESIGN: Prospective animal study. SETTING: Animal research laboratory. SUBJECTS: Sheep anesthetized with pentobarbital, mechanically ventilated, and monitored with pulmonary arterial and peripheral arterial catheters. INTERVENTIONS: A low output state was induced by inflating a balloon-tip catheter placed in the right atrium. Cardiac index was maintained at 1 L/min/m2 throughout the experiment in three groups of sheep: a) control (n=6) b)LNNA group (pretreated with the nitric oxide synthase inhibitor N omega-nitro-L-arginine [LNNA, 100 mg/kg, iv bolus, n=6); and c) dexamethasone group (pretreated with dexamethasone (6 mg/kg, intravenous bolus, n=6). Dexamethasone is an inhibitor of the induction of nitric oxide synthase. LNNA or dexamethasone were administered 15 mins before inducing the low output state. MEASUREMENTS AND MAIN RESULTS: Hemodynamic and oxygen transport variables, and plasma lactate and pyruvate concentrations, were measured at baseline and during the next 3 hrs. For a comparable decrease in cardiac index and oxygen delivery in all groups, the LNNA group had less hypotension and a more marked increase in systemic vascular resistance as compared with the control group. Oxygen consumption and oxygen extraction were higher in the LNNA group as compared with the control group at 30 and 60 mins. Plasma lactate concentration increased significantly less in the LNNA group than in the control and the dexamethasone groups during the observation period. CONCLUSIONS: Inhibition of nitric oxide synthesis during a severe low output state in sheep is associated with a better hemodynamic response, as evidenced by a greater vasoconstriction, and signs of less marked tissue hypoxia. It is likely that inhibition of nitric oxide synthesis in this model leads to an imbalance between the tonic relaxing action of nitric oxide and the influences of vasoconstrictor agents.

[A method for the predictive estimation of the surgical risk in adult cardiac pathology]. / Método de estimación predictiva de riesgo quirúrgico en patología cardíaca de adultos.

INTRODUCTION: In order to test the efficiency of statistical predictive models, we compare the results of a standard method (Parsonnet) with the model created through the data of our population. MATERIAL AND METHODS: We used the chi 2 univariate model, lineal and logistic regression with the data of the whole population receiving cardiac surgical procedure from January 1, 1990 to December 31, 1993 (total 1626 patients). The population was divided into a control group (1100 cases, 68%) and a study group (526 cases, 32%). The coefficients of the control group were used to estimate the results in the study group. RESULTS: Univariate model p value. Significant (p < 0.001) for emergency, age, pulmonary hypertension, left ventricular failure, preoperative use of intra-aortic balloon pump; p < 0.05 mitral valve disease, aortic aneurysm and reoperation. No significance (p < 0.01) was found for gender, aortic or tricuspid disease, percutaneous transluminal coronary angioplasty, unstable or postinfarction angina, transplant, left main or vessel disease number, and mitral, tricuspid or aortic procedure. MULTIVARIATE MODEL: Emergency, pulmonary hypertension, age, left ventricular dysfunction and aortic aneurysm. We estimated a 5.2%, 5.2% and 11.4% mortality with linear, logistic and Parsonnet method respectively with a real group mortality of 6.5%. The average error of the observed and predicted mortality after risk stratification was 5.7%, 6% and 12%. CONCLUSION: A model for risk prediction based on the data of the own institution is more accurate for that population than a model created for comparison between institutions, because the former takes account of the center and population peculiarities.

Inhibition of nitric oxide synthesis improves the vasoconstrictive effect of noradrenaline in sepsis.

BACKGROUND: Septic shock is characterized by systemic vasodilation and an impaired reactivity to vasoconstrictor agents. It has been suggested that an excessive release of nitric oxide has a role in this hemodynamic derangement. OBJECTIVE: To investigate whether inhibition of nitric oxide synthesis by the administration of N omega-nitro-L-arginine (LNNA), improves the vasoconstrictor effects of catecholamines in sepsis. MATERIAL AND METHODS: Mechanically ventilated and pentobarbital-anesthetized sheep received either no treatment (n = 6) or LNNA (100 mg/kg IV bolus, n = 4). Other sheep (septic group) received live Escherichia coli (E coli) (1,5* 10(9) micro-organisms/kg over 30 min) followed 1 hour later by either no treatment (n = 5) or LNNA (100 mg/kg IV bolus, n = 7). After those interventions, all sheep were given noradrenaline in a continuous IV infusion at three different doses (0.5, 1.5, and 4.5 micrograms, kg-1, min-1). Cardiovascular parameters were recorded at maximal blood pressure response achieved with each dose. RESULTS: The administration of live E coli to the septic group resulted in systemic hypotension, high cardiac output, and hyperlactatemia. The LNNA caused a significant systemic and pulmonary vasoconstriction in both septic and nonseptic sheep. In nonseptic sheep, noradrenaline induced a significant increase in systemic vascular resistance (from 2,973 +/- 637 to 4,561 +/- 1,287 dyn/s/cm-5/m-2), whereas the increase caused in those that received LNNA was nonsignificant (5,562 +/- 3,489 to 6,693 +/- 2,871 dyn, s, cm-5, m-2). Septic sheep showed a nonsignificant vasoconstriction during the infusion of noradrenaline (from 1,438 +/- 1,132 to 2,244 +/- 1,391 dyn/s/cm-5/m-2). However, treatment with LNNA markedly improved the vasoconstrictor effect of noradrenaline (from 2,804 +/- 2,317 to 4,894 +/- 3,435 dyn/s/cm-5/m-2). The dose-response curve of systemic vascular resistance in these LNNA-pretreated septic sheep became very similar to the corresponding curve obtained in nonseptic animals. CONCLUSIONS: Inhibition of nitric oxide synthesis by the administration of LNNA significantly improves the vasoconstrictor effect of noradrenaline in septic sheep, allowing an increase in systemic vasomotor tone similar to that observed in nonseptic sheep. It is concluded that increased synthesis of nitric oxide contributes to the depressed vascular reactivity to vasoconstrictor agents characteristic of sepsis.

L-arginine pathway in the sepsis syndrome.

OBJECTIVE: To investigate the role of nitric oxide in the regulation of vascular tone in patients with the sepsis syndrome. DESIGN: Prospective, intervention study. SETTING: Tertiary care hospital. PATIENTS: Fifteen patients admitted to our medical intensive care unit with the diagnosis of sepsis syndrome by defined criteria. INTERVENTIONS: Eight patients received N omega-nitro-L-arginine (20 mg/kg, iv bolus) followed by L-arginine (200 mg/kg, iv bolus). Seven patients received L-arginine alone (200 mg/kg). MEASUREMENTS AND MAIN RESULTS: In the first group, hemodynamic and oxygen transport variables were recorded at baseline, during 45 mins after the injection of N omega-nitro-L-arginine, and during 45 mins after the administration of L-arginine. In the second group, hemodynamic parameters were recorded at baseline and during 15 mins after the administration of L-arginine. Data are mean +/- SEM. The administration of N omega-nitro-L-arginine was followed by hypertension (mean blood pressure increased from 89 +/- 8 to a maximum of 140 +/- 12 mm Hg) accompanied by a decrease in cardiac index (from 3.51 +/- 0.39 to a minimum of 2.65 +/- 0.21 L/min/m2) and an increase in right atrial and pulmonary artery occlusion pressure. Systemic vascular resistance index increased from 1871.1 +/- 302.3 to 3825.6 +/- 244.4 dyne.sec/cm5.m2, and pulmonary vascular resistance increased from 533.2 +/- 125.8 to 816.0 +/- 117.3 dyne.sec/cm5.m2. These changes induced by N omega-nitro-L-arginine were reversed by the administration of L-arginine. The administration of L-arginine to another group of patients caused transient hypotension (from 103 +/- 6 to 81 +/- 10 mm Hg) and an increase in cardiac index (from 3.57 +/- 0.15 to 4.74 +/- 0.54 L/min/m2). Both systemic and pulmonary vascular resistance indices decreased (from 1987.6 +/- 163.9 to 1251.4 +/- 231.5 dyne.sec/cm5.m2, and from 486.1 +/- 65.2 to 380.5 +/- 70.3 dyne.sec/cm5.m2). Parallel to the increase in oxygen transport due to the increase in cardiac output, oxygen consumption index increased significantly 1 min after L-arginine (from 127.0 +/- 19.0 to 182.5 +/- 37.3 mL/min/m2). All mentioned changes were statistically significant (p < .05). CONCLUSIONS: A continuous basal release of nitric oxide plays a role in the regulation of systemic and pulmonary vascular tone in patients with sepsis syndrome. L-arginine has systemic and pulmonary vasodilatory actions.

Effects of blood transfusion on oxygen transport variables in severe sepsis.

OBJECTIVE: To investigate whether increasing oxygen delivery (DO2) by increasing hematocrit results in increases in oxygen uptake (VO2) in septic patients with an abnormal DO2/VO2 relationship. DESIGN: Prospective, randomized, interventional crossover study. SETTING: Tertiary care hospital. PATIENTS: A consecutive sample of 16 patients admitted to the intensive care unit, who were diagnosed as having severe sepsis by defined criteria and who had a hemoglobin concentration of < 10 g/dL. INTERVENTIONS: Patients received, in random order, an infusion of dobutamine (10 micrograms/kg/min) and a blood transfusion (800 mL of packed red blood cells in 90 mins). Hemodynamic and oxygen transport variables were determined before and after each treatment, allowing at least 20 mins during the infusion of dobutamine to achieve the steady state. MEASUREMENTS AND MAIN RESULTS: Changes in DO2 and VO2 induced by each intervention were measured. Dobutamine significantly increased DO2 (48.5 +/- 6.9%; p = .0001) and VO2 (21.7 +/- 3.3%; p = .0001). Blood transfusion increased DO2 (21.4 +/- 4.3%; p = .005) but VO2 did not change significantly (2.2 +/- 4.1%). Correlation coefficients for the percent changes of DO2 and VO2 (r2 = .67, p = .001 for dobutamine; and r2 = 21, p = .07 for blood transfusion) were significantly different for each treatment (p = .0001). CONCLUSIONS: In patients with an abnormal DO2-dependent VO2, as shown by increases in VO2 brought about by an infusion of dobutamine, blood transfusion does not significantly increase VO2, despite significant changes in DO2. The VO2, in some critically ill patients, depends more on blood flow than on global DO2.

Time course of hemostatic abnormalities in sepsis and its relation to outcome.

OBJECTIVES: To investigate the time course and the relation to prognosis of coagulation and fibrinolytic abnormalities in patients with septic shock. PATIENTS AND METHODS: Forty-eight consecutive patients admitted to the medical ICU with the diagnosis of septic shock (diagnosed by defined criteria) were studied. Mortality was 25 of 48. Mean age was 57 +/- 7.3 years. Blood samples were obtained on days 1, 4, and 7 after hospital admission to measure tissue-type plasminogen activator antigen (t-PA), urokinase-type plasminogen activator (u-PA), plasminogen activator inhibitor antigen (PAI-1), plasminogen, alpha 2-antiplasmin, fibrinogen, antithrombin III, protein C, protein S, thrombin-antithrombin complexes (TAT), D-dimer, and von Willebrand factor-related antigen (vWF:Ag). RESULTS: All patients showed marked abnormalities in both the coagulation and fibrinolytic systems. There were signs of coagulation activation and elevation of both activators and inhibitors of fibrinolysis. Nonsurvivors showed lower levels of protein C and antithrombin III and higher concentration of TAT than survivors. While both t-PA and PAI-1 concentrations were high in survivors and nonsurvivors, only survivors showed a progressive normalization of both parameters during the study period. Low plasminogen levels and plasminogen/alpha 2-antiplasmin ratio were found in both groups, presenting a trend toward normalization only in survivors. The differences reported were not apparent at the time of hospital admission. CONCLUSIONS: Septic shock is characterized by coagulation activation and fibrinolysis activation and inhibition. Nonsurvivors present a particular hemostatic profile characterized by a more marked activation of coagulation and a more intense inhibition of fibrinolysis. None of the abnormalities studied was significantly different between survivors and nonsurvivors at the time of hospital admission. In the presence of fibrin formation, nonsurvivors present a maintained imbalance in the fibrinolytic response determined by higher PAI-1 plasma concentration, probably contributing to their poor outcome.

Role of nitric oxide in the hemodynamic changes of sepsis.

OBJECTIVE: To study the role of nitric oxide in the hemodynamic changes of sepsis. DESIGN: Prospective, randomized, controlled, intervention study. SUBJECTS: Twenty-five sheep randomized to four groups: Group A (n = 8, nonseptic sheep) received NG-nitro L-arginine (20 mg/kg i.v.) followed 15 mins later by L-arginine (200 mg/kg i.v.); group B (n = 4, nonseptic sheep) received L-arginine followed 15 mins later by NG-nitro L-arginine; group C (n = 7, septic sheep) received NG-nitro L-arginine (20 mg/kg i.v.) alone; group D (n = 6, septic sheep) received L-arginine (200 mg/kg i.v.) followed by NG-nitro L-arginine (20 mg/kg i.v.). INTERVENTIONS: Sheep were anesthetized with pentobarbital, mechanically ventilated and monitored with a pulmonary artery catheter, a peripheral artery catheter, and a Miller catheter in the left ventricle. Sepsis was induced by the intravenous administration of live Escherichia coli (1.5 x 10(9) microorganisms/kg over 30 mins), which resulted in systemic hypotension, pulmonary hypertension, high cardiac output, and hyperlactatemia. Acetylcholine was administered before and after each intervention. MEASUREMENTS AND MAIN RESULTS: In nonseptic sheep (groups A and B) NG-nitro L-arginine induced an increase in mean blood pressure (BP), pulmonary arterial pressure, and systemic and pulmonary vascular resistances, accompanied by a decrease in cardiac index and the first derivative of left ventricular pressure. L-arginine administered to normal sheep induced systemic vasodilation. In the sepsis groups (groups C and D), the increases in BP and systemic vascular resistances induced by NG-nitro L-arginine were significant but less marked than in nonseptic sheep. Pretreatment of septic sheep with L-arginine totally abolished the NG-nitro L-arginine induced increases in systemic and pulmonary vascular resistances in this group. The administration of L-arginine in these animals induced both systemic and pulmonary vasodilation. Acetylcholine-mediated vasodilation was severely impaired in sepsis. In this condition, pretreatment with L-arginine improved the response to acetylcholine. CONCLUSIONS: These data support the view that nitric oxide plays a significant role in modulating systemic and pulmonary vasomotor tone in normal and septic sheep. L-arginine produced systemic vasodilation in normal sheep, whereas both systemic and pulmonary vasodilation were observed in septic animals. The impaired response to an endothelium-dependent vasodilator in sepsis was improved by the previous administration of L-arginine.

[The effects of prostacyclin on oxygen transport in adult respiratory distress syndrome]. / Efectos de la prostaciclina sobre el transporte de oxígeno en el síndrome de distrés respiratorio del adulto.

BACKGROUND: Patients with the adult respiratory distress syndrome (ARDS) present a deficit of tissue oxygenation which may be unmasked if increases in oxygen uptake (VO2) are observed when increases in oxygen delivery (DO2) are induced. Prostacyclin is a drug to which microvasodilator effects have been attributed and it has been proposed as an efficient agent for increasing histic enhancement of oxygen. METHODS: An infusion of prostacyclin was administered to 13 patients diagnosed with ARDS at doses of 10, 20, and 30 ng/kg per minute monitored with a Swan-Gatz catheter. RESULTS: The values are expressed as the percentage median of the increase with p less than 0.05 being considered as statistically significant. Prostacyclin significantly increased DO2 (10, 18 and 15% at the different doses). The VO2 rose significantly only following the first dose (13%). There was a correlation between the increase of DO2 and that of VO2 following the administration of the first dose (r = 0.70, p = 0.017. An important systemic vasodilator and pulmonary effect was observed accompanied by increases in the pulmonary (20, 56 and 59%) and reductions of PaO2 (-33.5, -40 and -48%) which may have been due to inhibition of hypoxic vasoconstriction. CONCLUSIONS: Prostacyclin is efficient for unmasking a lack of oxygen in patients with adult respiratory distress syndrome. The deleterious effects of this drug on systemic hemodynamics and on gaseous interchange makes not only the monitorization of arterial pressure but also of the parameters of gaseous interchanges necessary in these patients.

Oxygen delivery-dependent oxygen consumption in acute respiratory failure.

OBJECTIVE: To investigate whether oxygen consumption (VO2) is dependent on oxygen delivery (DO2) in adult respiratory distress syndrome (ARDS) and non-ARDS acute respiratory failure. DESIGN: Intervention study of a consecutive sample of patients admitted to the ICU with the diagnosis of acute respiratory failure. SETTING: Tertiary care center. PATIENTS: Thirteen consecutive patients with a diagnosis of ARDS and 11 with a diagnosis of respiratory failure not due to ARDS. Patients were monitored with an oximetric pulmonary artery catheter and mechanically ventilated. INTERVENTIONS: DO2 was decreased by the application of positive end-expiratory pressure (PEEP) (20 cm H2O), and subsequently increased by an iv infusion of dobutamine (10 micrograms/kg.min). RESULTS: After the application of PEEP, DO2 decreased significantly in both groups. However, VO2 decreased significantly (p less than .01) only in the ARDS group. When dobutamine was infused, DO2 increased significantly (p less than .01) in both groups, but VO2 increased only in ARDS patients. DO2 correlated significantly with VO2 both in ARDS (r2 = .81, p less than .01) and in non-ARDS (r2 = .38, p less than .05) patients. The correlation coefficient was significantly higher for ARDS than for non-ARDS patients. Comparing the slopes of the regression lines, a stronger dependency of VO2 on DO2 was found in ARDS than in non-ARDS respiratory failure (p less than .001). The oxygen extraction ratio correlated with DO2 in non-ARDS patients (r2 = .49, p less than .05), but not in ARDS patients. CONCLUSIONS: VO2 is dependent on DO2 over a wide range of DO2 values in acute respiratory failure. This dependency phenomenon is much stronger in ARDS than in respiratory failure due to other causes. Due to the abnormal dependency of VO2 on DO2, changes in the oxygenation status may not be reflected by changes in mixed venous oxygen saturation in ARDS.