| 1. |
- Jungner, Åsa, et al.
(författare)
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Cardiopulmonary bypass in the newborn: effects of circulatory cell-free hemoglobin and hyperoxia evaluated in a novel rat pup model
- 2017
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Ingår i: Intensive Care Medicine Experimental. - : Springer Science and Business Media LLC. - 2197-425X. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Infants with congenital heart defects (CHD) are at risk for white matter brain injury. This novel rat pup model characterizes the systemic effects of intravasal cell-free hemoglobin and hyperoxia, hypothesizing that immature endogenous scavenging systems relate to increased vulnerability to conditions present during cardiopulmonary bypass (CPB).Methods: Plasma pharmacokinetics of cell-free human hemoglobin (Hb) was determined after intraperitoneal (i.p.) administration in postnatal day 6 (P6) rat pups. Cell-free hemoglobin degradation, scavenger- and oxidative stress responses in altered oxygen environments were evaluated in P6 rat pups exposed to i.p. cell-free Hb or vehicle and subjected to hyperoxia or normoxia for 24 h. Plasma and liver were analyzed for free heme, haptoglobin, hemopexin, heme-oxygenase 1, and 8-OHdG at 3–120 h post-injection. Baseline scavenging properties were evaluated in P0-P12 rat pups.Results: Cell-free Hb displayed peak plasma concentrations of 3.6 ± 0.5 mg/mL (mean ± SD) at 3 h post-administration. Animals exposed to cell-free Hb demonstrated a 30-fold increase in plasma haptoglobin and a decrease in plasma hemopexin to 1/6 of concentrations observed in pups exposed to vehicle. Exposure to cell-free Hb and hyperoxia mediated increased plasma concentrations of free heme (72.7 ± 19.5 μM, mean ± SD) compared to exposure to cell-free Hb and normoxia (49.3 ± 13.1 μM) at 3 h, and an elevated hepatic mRNA expression of heme-oxygenase 1. mRNA expression of haptoglobin and hemopexin was increased in animals exposed to hemoglobin with a mitigated response in pups exposed to hemoglobin and hyperoxia. Animals exposed to hyperoxia displayed an increase in hepatic transcription of scavenger proteins at 24 h. Combined exposure to cell-free Hb and hyperoxia mediated an increased DNA- oxidation at 6 h, whereas all insults conveyed a decrease in DNA-oxidation at 120 h.Conclusions: In this study, we present a novel rat pup model with scavenging characteristics and brain maturation similar to newborns with CHD. We have confirmed a distinct scavenger response after exposure to systemic cell-free hemoglobin. We have indications of an accelerated metabolism of cell-free Hb and of an altered transcription of scavenger proteins in a hyperoxic environment. We believe that this model will prove valuable in future delineation of inflammatory and oxidative end-organ damage following CPB.
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| 2. |
- Karagiannidis, Christian, et al.
(författare)
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Impact of membrane lung surface area and blood flow on extracorporeal CO2 removal during severe respiratory acidosis
- 2017
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Ingår i: Intensive Care Medicine Experimental. - : Springer Science and Business Media LLC. - 2197-425X. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Veno-venous extracorporeal CO2 removal (vv-ECCO2R) is increasingly being used in the setting of acute respiratory failure. Blood flow rates through the device range from 200 ml/min to more than 1500 ml/min, and the membrane surface areas range from 0.35 to 1.3 m2. The present study in an animal model with similar CO2 production as an adult patient was aimed at determining the optimal membrane lung surface area and technical requirements for successful vv-ECCO2R.METHODS: Four different membrane lungs, with varying lung surface areas of 0.4, 0.8, 1.0, and 1.3m2 were used to perform vv-ECCO2R in seven anesthetized, mechanically ventilated, pigs with experimentally induced severe respiratory acidosis (pH 7.0-7.1) using a 20Fr double-lumen catheter with a sweep gas flow rate of 8 L/min. During each experiment, the blood flow was increased stepwise from 250 to 1000 ml/min.RESULTS: Amelioration of severe respiratory acidosis was only feasible when blood flow rates from 750 to 1000 ml/min were used with a membrane lung surface area of at least 0.8 m2. Maximal CO2 elimination was 150.8 ml/min, with pH increasing from 7.01 to 7.30 (blood flow 1000 ml/min; membrane lung 1.3 m2). The membrane lung with a surface of 0.4 m2 allowed a maximum CO2 elimination rate of 71.7 mL/min, which did not result in the normalization of pH, even with a blood flow rate of 1000 ml/min. Also of note, an increase of the surface area above 1.0 m2 did not result in substantially higher CO2 elimination rates. The pressure drop across the oxygenator was considerably lower (<10 mmHg) in the largest membrane lung, whereas the smallest revealed a pressure drop of more than 50 mmHg with 1000 ml blood flow/min.CONCLUSIONS: In this porcine model, vv-ECCO2R was most effective when using blood flow rates ranging between 750 and 1000 ml/min, with a membrane lung surface of at least 0.8 m2. In contrast, low blood flow rates (250-500 ml/min) were not sufficient to completely correct severe respiratory acidosis, irrespective of the surface area of the membrane lung being used. The converse was also true, low surface membrane lungs (0.4 m2) were not capable of completely correcting severe respiratory acidosis across the range of blood flows used in this study.
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| 3. |
- Nilsson, Kristofer F., 1981-, et al.
(författare)
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The novel nitric oxide donor PDNO attenuates ovine ischemia-reperfusion induced renal failure
- 2017
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Ingår i: Intensive Care Medicine Experimental. - London, UK : Springer Science and Business Media LLC. - 2197-425X. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Renal ischemia-reperfusion injury is a common cause of acute kidney injury in intensive care and surgery. Recently, novel organic mononitrites of 1,2-propanediol (PDNO) were synthesized and shown to rapidly and controllably deploy nitric oxide in the circulation when administered intravenously. We hypothesized that intravenous infusion of PDNO during renal ischemia reperfusion would improve post-ischemic renal function and microcirculation.METHODS: Sixteen sheep were anesthetized, mechanically ventilated, and surgically instrumented. The left renal artery was clamped for 90 min, and the effects of ischemia were studied for a total of 8 h. Fifteen minutes prior to the release of the clamp, intravenous infusions of PDNO (n = 8) or vehicle (1,2 propanediol + inorganic nitrite, n = 8) were initiated (180 nmol/kg/min for 30 min, thereafter 60 nmol/kg/min for the remainder of the experiment).RESULTS: Renal artery blood flow, cortical and medullary perfusion, and diuresis and creatinine clearance decreased in the left kidney post ischemia. However, in the sheep treated with PDNO, diuresis and creatinine clearance in the left kidney were significantly higher post ischemia compared to vehicle-treated animals (1.7 ± 0.5 vs 0.7 ± 0.3 ml/kg/h, p = 0.04 and 7.5 ± 2.1 vs 1.7 ± 0.6 ml/min, p = 0.02, respectively). Left renal medullary perfusion and oxygen uptake were higher in the PDNO group (73 ± 9 vs 37 ± 5% of baseline, p = 0.004 and 2.6 ± 0.4 vs 1.6 ± 0.3 ml/min, p = 0.02, respectively). PDNO significantly increased renal oxygen consumption and reduced the oxygen utilization for sodium reabsorption (p = 0.03 for both). Mean arterial blood pressure was significantly reduced by PDNO (83 ± 3 vs 94 ± 3 mmHg, p = 0.02) but was still within normal limits. Total renal blood flow was not affected, and there were no signs of increased blood methemoglobin concentrations or tachyphylaxis.CONCLUSIONS: The novel nitric oxide donor PDNO improved renal function after ischemia. PDNO also prevented the persistent reduction in medullary perfusion during reperfusion and improved renal oxygen utilization without severe side effects.
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| 4. |
- Sperber, Jesper, et al.
(författare)
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Protective ventilation reduces Pseudomonas aeruginosa growth in lung tissue in a porcine pneumonia model
- 2017
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Ingår i: Intensive & Critical Care Nursing. - : Springer Science and Business Media LLC. - 0964-3397 .- 1532-4036. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Mechanical ventilation with positive end expiratory pressure and low tidal volume, i.e. protective ventilation, is recommended in patients with acute respiratory distress syndrome. However, the effect of protective ventilation on bacterial growth during early pneumonia in non-injured lungs is not extensively studied. The main objectives were to compare two different ventilator settings on Pseudomonas aeruginosa growth in lung tissue and the development of lung injury.METHODS: A porcine model of severe pneumonia was used. The protective group (n = 10) had an end expiratory pressure of 10 cm H2O and a tidal volume of 6 ml x kg-1. The control group (n = 10) had an end expiratory pressure of 5 cm H2O and a tidal volume of 10 ml x kg-1. 1011 colony forming units of Pseudomonas aeruginosa were inoculated intra-tracheally at baseline, after which the experiment continued for 6 h. Two animals from each group received only saline, and served as sham animals. Lung tissue samples from each animal were used for bacterial cultures and wet-to-dry weight ratio measurements.RESULTS: The protective group displayed lower numbers of Pseudomonas aeruginosa (p < 0.05) in the lung tissue, and a lower wet-to-dry ratio (p < 0.01) than the control group. The control group deteriorated in arterial oxygen tension/inspired oxygen fraction, whereas the protective group was unchanged (p < 0.01).CONCLUSIONS: In early phase pneumonia, protective ventilation with lower tidal volume and higher end expiratory pressure has the potential to reduce the pulmonary bacterial burden and the development of lung injury.
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| 5. |
- Statkevicius, Svajunas, et al.
(författare)
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Effect of Ringer´s acetate in different doses on plasma volume in rat models of hypovolemia
- 2017
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Ingår i: Intensive Care Medicine Experimental. - : Springer Science and Business Media LLC. - 2197-425X. ; 5, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Even though crystalloids are the first choice for fluid resuscitation in hemodynamically unstable patients, their potency as plasma volume expanders in hypovolemia of different etiologies is largely unknown. The objective of the study was to investigate dose-response curves of a crystalloid in hypovolemia induced by either sepsis or hemorrhagic shock.RESULTS: Rats were randomized to resuscitation with Ringers acetate at a dose 10, 30, 50, 75, or 100 ml/kg at 4 h after induction of sepsis by cecal ligation and puncture (CLP) or 2.5 h after a 30 ml/kg hemorrhage. Plasma volume (125I-albumin) was the primary outcome. Plasma volume decreased by about 11.8 (IQR 9.9-14.5) ml/kg relative baseline after CLP and increased dose-dependently by at most 5.8 (IQR 3.3-7.0) ml/kg in the 100 ml/kg group at 15 min after resuscitation. In the hemorrhage group, the plasma volume increased by at most 13.8 (IQR 7.1-15.0) ml/kg in 100 ml/kg group. Blood volumes at baseline, calculated using hematocrit and plasma volumes, were 72.4 (IQR 68.2-79.5) ml/kg in sepsis group and 71.1 (IQR 69.1-74.7) ml/kg in hemorrhage group. At 15 min after resuscitation with a dose of 100 ml/kg blood volumes increased to 54.8 (IQR 52.5-57.7) ml/kg and ; 49.6 (IQR 45.3-56.4) ml/kg, in the sepsis and hemorrhage groups, respectively. Plasma volume expansion as the percentage of dose at 15 min was 5.9 (IQR 2.5-8.8)% and 14.5 (IQR 12.1-20.0)% in the sepsis and hemorrhage groups, respectively. At 60 min, average plasma volume as the percentage of dose had decreased to 2.9 (IQR ([-2.9] - 8.3)% (P = 0.006) in the sepsis group whereas no change was detected in the hemorrhage group. A dose-dependent decrease in the plasma oncotic pressure, which was more marked in sepsis, was detected at 60 min after resuscitation.CONCLUSIONS: We conclude that the efficacy of Ringers acetate as a plasma volume expander is context dependent and that plasma volume expansion is lower than previously realized across a wide range of doses. Ringers acetate decreases plasma oncotic pressure in sepsis, in part, by mechanisms other than dilution.
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| 6. |
- Söderberg, Ewa, et al.
(författare)
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The impact of hydrocortisone treatment on neutrophil gelatinase-associated lipocalin release in porcine endotoxemic shock
- 2017
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Ingår i: Intensive Care Medicine Experimental. - : Springer. - 2197-425X. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A key feature of sepsis is systemic inflammatory activation that could be counteracted by steroids. In this experimental model of systemic inflammation, we sought to investigate whether septic neutrophil activation, evaluated by the plasma levels of neutrophil gelatinase-associated protein (NGAL), is modulated by the timing of hydrocortisone treatment.METHODS: Sixteen anesthetized pigs were allocated to one of four equally sized groups. Three of these groups received endotoxin at 2 μg × kg(-1) × h(-1) for 6 h so as to induce endotoxemic shock. Hydrocortisone (5 mg × kg(-1)) was administered intravenously before endotoxemic challenge, or at the onset of endotoxemic shock. Endotoxemic pigs not receiving hydrocortisone and non-endotoxemic pigs served as control groups. Physiologic variables, hematology, and biochemistry, including plasma NGAL, were measured repeatedly.RESULTS: Hydrocortisone treatment prior to endotoxemia attenuated some inflammatory, hematological, circulatory, and metabolic manifestations of shock (i.e., higher white blood cell count, higher mean arterial pressure, lower heart rate and mean pulmonary arterial pressure, higher left ventricular stroke work index, higher base excess). Endotoxemic shock increased plasma NGAL (p < 0.001). In pigs given hydrocortisone before the endotoxin infusion, plasma NGAL was lower as compared to those given hydrocortisone at endotoxemic shock (p < 0.05). Plasma NGAL levels correlated inversely to neutrophil granulocyte counts (rho = -0.65) but not to urine output (rho = -0.10) at the end of the experiment.CONCLUSIONS: The increase in plasma NGAL is counteracted by hydrocortisone administration prior to endotoxemia; concomitantly, this treatment was associated with less expressed circulatory derangement. Urine NGAL did not differ between the groups, suggesting that the NGAL response was not primarily related to kidney injury.
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