| 1. |
- Kimblad, Per Ola, et al.
(författare)
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High potassium contents in organ preservation solutions cause strong pulmonary vasocontraction
- 1991
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Ingår i: Annals of Thoracic Surgery. - 1552-6259. ; 52:3, s. 523-528
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Tidskriftsartikel (refereegranskat)abstract
- Euro-Collins (ECS) and UCLA-formula organ preservation solutions induced strong vasocontraction in porcine pulmonary arteries when studied in organ baths at temperatures of 37 degrees C and 30 degrees C. At 20 degrees C ECS induced a 30% contraction, but at 6 degrees C no contraction (n = 5) or a weak contraction (n = 1) was elicited. Neither prostaglandin E1 nor nifedipine caused any significant reduction of the vasocontraction elicited by ECS and UCLA. Krebs solution, enriched with potassium in amounts corresponding to those in ECS (115 mmol/L) or UCLA (30 mmol/L), induced vasocontraction comparing well with those induced by ECS or UCLA, indicating that it is the high potassium content that causes the vasocontraction. In a second experiment lung segments were stored at 4 degrees C for 9 hours in ECS, UCLA, or Krebs solution. Pulmonary arterial segments were then studied in organ baths at 37 degrees C. The choice of preservation solution did not significantly affect the contractile properties of potassium, noradrenaline, or the thromboxane mimic U-46619. To conclude, high potassium contents in organ preservation solutions induce strong pulmonary vasocontraction in lung temperatures greater than 20 degrees C but not in temperatures less than 10 degrees C. These vasocontractions are not significantly reduced by prostaglandin E1 or nifedipine. We suggest that the initial preservation solution used to cool down the lungs should contain 4 mmol/L or no potassium. When the lung temperature is less than 10 degrees C, a second perfusion might be done, and then a high potassium content (if thought to be essential) will not cause vasocontraction.
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| 2. |
- Koul, Bansi, et al.
(författare)
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Pulmonary sequelae of prolonged total venoarterial bypass: evaluation with a new experimental model
- 1991
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Ingår i: Annals of Thoracic Surgery. - 1552-6259. ; 51:5, s. 794-799
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Tidskriftsartikel (refereegranskat)abstract
- Total normothermic venoarterial bypass was established in 6 healthy pigs over a period of 18 hours. A heparin-coated closed extracorporeal system was used and no heparin was administered systemically. During the bypass period the main pulmonary artery was occluded and the heart was maintained in a beating state. All the animals maintained stable hemodynamics and normal blood gases during the entire period of bypass. In the postbypass period, the central hemodynamics continued to be stable while the arterial oxygen tension (inspired oxygen fraction = 0.21) decreased significantly (p less than or equal to 0.05). The total body oxygen uptake, on the other hand, remained unaltered. All the animals died within 4 hours after weaning off the venoarterial bypass circuit on account of pulmonary edema in 2 and cardiac arrest in 4. Death was preceded by progressive pulmonary hypertension and lactacidosis in all the animals. Histological examination of the lungs showed pulmonary parenchymal damage ranging from interstitial edema to intraalveolar hemorrhage and parenchymal necrosis involving more than 80% of the pulmonary parenchyma. A normothermic total venoarterial bypass of 18 hours duration or more produces pulmonary edema of varying severity, pulmonary hypertension, pulmonary parenchymal necrosis, and lactacidosis in healthy juvenile pigs, resulting uniformly in their death. Despite these sequelae the systemic arterial hypoxemia may only be mild to moderate.
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| 3. |
- Koul, Bansi, et al.
(författare)
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Veno-right ventricular bypass as total extracorporeal lung assistance. An experimental study
- 1991
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Ingår i: Journal of Thoracic and Cardiovascular Surgery. - 1097-685X. ; 101:4, s. 719-723
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Tidskriftsartikel (refereegranskat)abstract
- Efficacy of veno-right ventricular bypass as a total extracorporeal lung assistance was studied for a period of 24 hours in six healthy pigs with a mean weight of 60 kg. A covalently bonded heparin-coated extracorporeal membrane oxygenation system and a roller pump were used for the bypass. No local or systemic heparin was administered. The bypass was established with an open chest with two 28F venous cannulas and one 24F arterial cannula. The arterial cannula was placed in the right ventricle across the tricuspid valve. With the lung function totally disabled, this extracorporeal lung assistance maintained normal systemic arterial and mixed venous blood gases during the entire 24-hour period in all the animals. No significant tricuspid insufficiency was observed, and the animals maintained normal central hemodynamics. There was no hemolysis, and the platelet counts remained essentially unaltered. Multiple foci of clot formation were observed in all the oxygenators, but no macroscopic thrombosis or embolization was seen either in the heart or in the lungs. A veno-right ventricular bypass offers total extracorporeal lung assistance in 60 kg juvenile pigs for a period of 24 hours. Tricuspid valve competence is an important prerequisite for the success of this procedure.
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| 4. |
- Massa, G, et al.
(författare)
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Might free arterial grafts fail due to spasm?
- 1991
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Ingår i: Annals of Thoracic Surgery. - 1552-6259. ; 51:1, s. 94-101
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Tidskriftsartikel (refereegranskat)abstract
- The rat femoral artery was used as a free graft and was studied after 2, 7, 14, 30, and 60 days. The patency of the grafts was 100% (2 days, n = 6), 78% (7 days, n = 9), 63% (14 days, n = 8), 33% (30 days, n = 12), and 18% (60 days, n = 11). Histology showed an intimal thickening after 14 days and the media, which in the controls consisted of eight to ten layers of myocytes, was reduced to six to eight cell layers. During the first 2 weeks the graft segments had an impaired contraction when exposed to Krebs solution with 124 mmol/L K+, whereas after 1 month and later the graft segments approached the controls or had even higher contractile force. The thromboxane mimic U-46619 elicited full contractile force at all times whereas the potency was significantly lower during the first 14 days. Noradrenaline was unable to induce contraction in the graft segments during the first 14 days, but at 30 and 60 days it had regained full contractile force and was significantly more potent (approximately 60 times) in the graft segments compared with the controls. This study suggests that intimal thickening and hypercontractility might be a problem in free muscular arterial grafts.
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| 5. |
- Sjöberg, Trygve, et al.
(författare)
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Contractile properties of lymphatics from the human lower leg
- 1991
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Ingår i: Lymphology. - 0024-7766. ; 24:1, s. 16-21
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Tidskriftsartikel (refereegranskat)abstract
- Lower leg lymphatics, taken from seven volunteers, were investigated in vitro. Isometric contractions were induced by noradrenaline, 5-hydroxytryptamine (5-HT), prostaglandin F2 alpha (PGF2 alpha), and the thromboxane A2 (TXA2)-mimetic U-44069. Noradrenaline induced phasic contractions in 6 of 7 segments. The amplitude of the contractions were up to 100% of a previous K+ (124mM)-induced contraction and the frequency at 10(-6)M of noradrenaline was 5-13 min-1. These contractions were unaffected by propranolol (10(-6)M), but they were abolished by phentolamine (10(-6)M). Noradrenaline had an Emax (tonic contraction) of 7% of the K+ (124mM) contraction (n = 7) and the pEC50-value was 6.9 (n = 3). The corresponding values for 5-HT were 21% (n = 5) and 6.4 (n = 3). PGF2 alpha elicited contractions in all segments investigated (Emax = 87%, pEC50 = 5.8, n = 5). U-44069 had high contractile capacity and potency in all investigated segments (Emax = 137%, pEC50 = 8.9, n = 7). Phasic contractions were elicited also by 5-HT, PGF2 alpha and U-44069. Compared to earlier studies of human peripheral lymphatics, these results show that there are regional differences in susceptibility to these vasoactive agents.
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| 6. |
- Sjöberg, Trygve, et al.
(författare)
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In vitro effects of a thromboxane A2-analogue U-46619 and noradrenaline on contractions of the human thoracic duct
- 1991
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Ingår i: Lymphology. - 0024-7766. ; 24:3, s. 113-115
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Tidskriftsartikel (refereegranskat)abstract
- A piece of a human thoracic duct removed at operation was investigated in organ baths. The duct was cut in 8 ring segments each about 1mm long and isometric tension recorded. The segments were exposed to a potassium rich (124mM) Krebs buffer solution. In only two of the segments were contractions induced (7.2 and 1.0mN, respectively). Noradrenaline and the thromboxane mimetic U-46619 induced tonic and phasic contractions. At a noradrenaline concentration of 10(-5)M the phasic contractions had a frequency of 5 min-1. The highest frequency, 9 min-1, was recorded with 3 x 10(-10)M of U-46619 present in the bath. Noradrenaline had a mean Emax of 50% of the previous K+ (124mM)-induced contraction, and the mean pEC50-value was 6.7. The Emax and pEC50-values of U-46619 were 142% and 9.5, respectively. Postjunctional alpha-adrenoceptors and thromboxane A2-receptors may play a role in the contractility of the human thoracic duct.
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| 7. |
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| 8. |
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| 9. |
- Wetterberg, T, et al.
(författare)
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Total extracorporeal lung assist--a new clinical approach
- 1991
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Ingår i: Intensive Care Medicine. - 0342-4642. ; 17:2, s. 73-77
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Tidskriftsartikel (refereegranskat)abstract
- Total extracorporeal lung assist (ECLA) requires a bypass flow approaching cardiac output. Recirculation of venous blood through the oxygenator is minimized with a veno-right ventricular cannulation technique which separates venous drainage from returned oxygenated blood. A case of posttraumatic ARDS was treated with surface-heparinized veno-right ventricular ECLA for 35 days. Cardiac output was stabilized by means of sedation, hypothermia (35 degrees C) and beta blockers (pulse rate less than 90) in order to match the maximal venous drainage achieved (5.5 l/min). A bypass flow around 85% of cardiac output resulted in mean arterial PO2 values between 9-13.6 kPa without any contribution from the lungs. Low platelet counts and a marked bleeding tendency complicated treatment, even though no heparin was used during the last 24 days of ECLA. Weaning from the ventilator was accomplished 2 months after ECLA. Lung function tests show constant improvement.
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