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 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of sufentanil on human cerebral blood flow (CBF) was studied in seven unpremedicated, healthy volunteers 31 +/- 3.5 yr of age (mean +/- SD) and either sex. CBF (ml.100 g-1.min-1) was measured noninvasively with the 133Xe clearance technique and a scintillation camera before and after sufentanil 0.5 micrograms/kg administered intravenously. This technique provides values for global blood flow and for gray and white matter blood flow, and from 13 preselected regions in one hemisphere. After the administration of sufentanil, the volunteers were stimulated verbally in order to prevent their loss of consciousness and hypercarbia. Heart rate (HR), arterial pressure, oxyhemoglobin saturation, and end-tidal CO2 (ETCO2 were recorded during the measurements. Neither global CBF (46.1 +/- 1.6 control and 43 +/- 1.9 after sufentanil, mean +/- SEM) nor gray (76.5 +/- 3.2 and 70.9 +/- 6.1) or white (22.7 +/- 1.5 and 24.2 +/- 1.6) matter blood flow changed significantly after sufentanil administration. As well, no significant differences in HR (72 +/- 4 control and 79 +/- 4 beats per min after sufentanil) and ETCO2 (39.8 +/- 1.4 and 41.1 +/- 1.1 mmHg) were observed. It is concluded that sufentanil has no significant effect on CBF in healthy human volunteers.
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PMID:Sufentanil does not increase cerebral blood flow in healthy human volunteers. 214 62

1. Calcium-entry blockers increase the intramyocardial pH and decrease the intramyocardial Pco2 of ischaemic canine myocardium. However, the evidence documenting improvements in myocardial acidosis and in myocardial resuscitability after administration of calcium-entry blockers during cardiac arrest is incomplete. We therefore compared the effects of verapamil (0.05 mg/kg) and diltiazem (0.075 mg/kg) with those of saline placebo in an established porcine model of cardiac arrest and cardiopulmonary resuscitation. 2. After verapamil, six of 11 animals were successfully resuscitated; after diltiazem, five of 10; and after saline placebo, six of 10. Coronary perfusion and mean aortic pressures together with end-tidal CO2 concentration during precordial compression were predictive of resuscitation, independently of the drug or placebo. 3. Coronary vein pH decreased to 6.91 +/- 0.06 units (mean +/- SEM) with concurrent increases in PCO2 to levels exceeding 100 mmHg. Coronary vein lactate increased to a maximum of 7.5 +/- 0.6 mmol/l. Coronary vein acidaemia was accompanied by decreases in intramyocardial pH to 6.64 +/- 0.06 units. However, each of these differences between success and failure of resuscitation was unrelated to treatment with calcium-entry blockers. 4. Accordingly, neither verapamil nor diltiazem selectively altered coronary perfusion pressure, attenuated intramyocardial acidosis or improved resuscitability after porcine cardiac arrest and cardiopulmonary resuscitation.
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PMID:Calcium-entry blockers during porcine cardiopulmonary resuscitation. 215 50

1. The aim of this investigation was to measure the change in intracellular pH of human brain in vivo in response to hypercapnia. 2. Five healthy male subjects inspired air for 20 min and then 5% CO2/95% O2 for 30 min, of which the first 10 min was used to achieve a steady-state end-tidal CO2 measurement. 3. 31P nuclear magnetic resonance spectroscopy was used to measure intracellular pH while breathing air and during hypercapnia. Simultaneous localization between superficial and deep brain was achieved by using the phase-modulated rotating frame imaging technique. One subject volunteered to breath air for a further phase-modulated rotating frame imaging study while recovering from hypercapnia. 4. End-tidal CO2 increased when breathing 5% CO2/95% O2 (on air, 5.57 +/- 0.21%; on 5% CO2/95% O2, 6.41 +/- 0.16%; rise = +0.84 +/- 0.09%; means +/- SEM) causing a reduction in brain intracellular pH, which was more pronounced in deep brain (5 cm = mainly white matter, from 7.02 +/- 0.006 pH units to 6.96 +/- 0.001 pH units, mean +/- SEM) than in superficial brain (2 cm = mainly grey matter, from 7.02 +/- 0.006 pH units to 7.00 +/- 0.006 pH units, mean +/- SEM). 5. The white matter responded to hypercapnia with a greater fall in intracellular pH than the grey matter. This could either be due to differences in blood flow between grey and white matter in response to hypercapnia or to differences in intracellular pH regulation/buffering between these two tissues.
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PMID:Response of the human brain to a hypercapnic acid load in vivo. 216 84

The effect of release of intraoperative thigh tourniquets on velocity of blood flow in the middle cerebral artery was examined in five patients given general anesthesia with controlled ventilation for lower extremity orthopedic procedures using transcranial Doppler sonography. Middle cerebral artery blood flow velocity increased significantly from 52 +/- 6 (SEM) to 82 +/- 24 cm/s (an increase of 58% +/- 13%) within 4 +/- 1 min after tourniquet release and remained significantly elevated for 7 min. A positive linear correlation was found between middle cerebral artery blood flow velocity and PETCO2 on each occasion (0.97 greater than or equal to r greater than or equal to 0.84, 0.001 greater than P greater than 0.0001) after tourniquet deflation. Assuming a linear relationship between flow velocity and flow, these findings suggest that significant increase in cerebral blood flow can occur after intraoperative tourniquet release and that this increase appears to be mostly CO2-dependent.
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PMID:Changes in cerebral blood flow velocity after release of intraoperative tourniquets in humans: a transcranial Doppler study. 222 10

The purpose of this study was to test the hypothesis that prostaglandins released from vascular endothelial cells contribute to activation of baroreceptors during increases in arterial pressure. Baroreceptor activity was recorded from the vascularly isolated carotid sinus in rabbits anesthetized with chloralose. Baroreceptor activity was measured during ramp or step increases in nonpulsatile carotid sinus pressure over a range of 0-175 mm Hg. Exposure of the isolated carotid sinus to inhibitors of prostaglandin formation (indomethacin [n = 10] or aspirin [n = 6]) decreased baroreceptor activity significantly (p less than 0.05). The slope of the pressure-activity relation averaged 0.80 +/- 0.07 %/mm Hg (mean +/- SEM) during control measurements and 0.72 +/- 0.06 and 0.63 +/- 0.05 %/mm Hg during exposure to 10 and 20 microM indomethacin, respectively. Exposure of the carotid sinus to exogenous prostacyclin (PGI2 [n = 11]) increased baroreceptor activity significantly. The slope of the pressure-activity relation averaged 0.89 +/- 0.10, 1.09 +/- 0.09, and 1.26 +/- 0.16 %/mm Hg during control and during exposure to 10 and 20 microM PGI2, respectively. Activity returned to control after removal of PGI2 (0.89 +/- 0.12 %/mm Hg). Removal of endothelium with either a balloon catheter (n = 4) or a jet of a 95% O2-5% CO2 gas mixture (n = 6) decreased the slope of the pressure-activity relation from 0.92 +/- 0.09 to 0.56 +/- 0.08 %/mm Hg (p less than 0.05). Exposure of the denuded sinus to exogenous PGI2 (20 microM [n = 4]) restored activity (slope = 1.09 +/- 0.24 %/mm Hg). Neither indomethacin (n = 5) nor PGI2 (n = 5) nor denudation (n = 5) significantly altered the pressure-diameter relation of the carotid sinus (sonomicrometers), suggesting that the effects on baroreceptor discharge are not caused by altered stretch of the carotid sinus at a given pressure. The results suggest that prostaglandins (e.g., PGI2) released from endothelium contribute in a paracrine manner to activation of baroreceptors during increases in arterial pressure.
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PMID:Prostaglandins contribute to activation of baroreceptors in rabbits. Possible paracrine influence of endothelium. 224 1

Nitrous oxide has a long clinical history, but its effects on the heart remain controversial. The direct effects of N2O on global myocardial function have not been reported. The authors' aim was to examine the inotropic, chronotropic, dromotropic, and vascular effects of N2O, compared with its N2 control, on hearts isolated from the guinea pig. Hearts (N = 31) were isolated and perfused at 37 degrees C with Krebs-Ringer solution at constant pressure. Isovolumetric left ventricular pressure (LVP) and its derivative (maximum rate of tension development [dP/dtmax]) were measured by placing a saline-filled, latex balloon into the left ventricle. Bipolar electrodes were placed in the right atrium and right ventricle for measurement of heart rate (HR) and atrioventricular conduction time (AVCT). The venae cavae were ligated, and the right ventricle was cannulated through the pulmonic valve to collect coronary sinus effluent for measurement of coronary outflow O2 tension, adenosine, and inosine. After stabilization and perfusion with 96% O2 (plus 4% CO2), each heart was exposed for 10 min either to 48% N2O or to 48% N2 with 48% O2. After repeated perfusion with 96% O2 for 10 min, hearts were exposed in the reverse order to 48% N2O or 48% N2. In the postcontrol period, hearts were again exposed to 96% O2. Inflow Po2 (in mmHg) was 506 +/- 5 (standard error of the mean [SEM]) during 96% O2 and 258 +/- 5 during both 48% N2 and 48% N2O. Effluent Po2 was 155 +/- 7 during 96% O2, 81 +/- 5 during 48% N2, and 83 +/- 5 during 48% N2O.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of nitrous oxide on contractile function and metabolism of the isolated heart. 224 99

A study was conducted to evaluate the adaptability to the tiger of an in vitro fertilization/embryo culture system previously developed in the domestic cat. In Trial I (July 1989), 10 female tigers were treated with either 2,500 (n = 5) or 5,000 (n = 5) IU eCG i.m. and with 2,000 IU hCG i.m. 84 h later. In Trial II (January 1990), 6 females (5 of which were treated in Trial I) were given 2,500 IU eCG i.m. and 2,000 IU hCG i.m. 84 h later. Twenty-four to twenty-six hours after hCG treatment, all tigers were subjected to laparoscopy, and oocytes were aspirated transabdominally. On the basis of follicular development (follicles greater than or equal to 2 mm in diameter), all females responded to exogenous gonadotropins (range, 6-52 follicles/female). Follicle number and oocyte recovery rate were unaffected (p greater than 0.05) by eCG dose or time of year. A total of 456 oocytes were collected from 468 follicles (97.4% recovery; mean, 28.5 +/- 3.4 oocytes/female). Of these, 378 (82.9%) qualified as mature, 48 (10.5%) as immature, and 30 (6.6%) as degenerate. During Trial I, 8 electroejaculates were collected from 7 male tigers, and in Trial II, 3 semen samples were collected from 3 males. Motile sperm were recovered on each occasion; the overall mean (+/- SEM) ejaculate volume was 7.5 +/- 0.7 ml, the number of motile sperm/ejaculate was 105.9 +/- 20.6 x 10(6), and the percentage of structurally normal sperm/ejaculate was 81.4 +/- 2.0%. After swim-up processing, 0.05 x 10(6) motile sperm were co-cultured with 10 or fewer tiger oocytes in a humidified atmosphere (38 degrees C) of 5% CO2 in air. Of the 358 mature oocytes inseminated, 227 (63.4%) were fertilized. Oocytes from 2 females became contaminated in culture and, therefore, were excluded from embryo cleavage calculations. Of the remaining 195 fertilized oocytes, 187 (95.9%) cleaved to the two-cell stage. No parthenogenetic cleavage was observed in noninseminated control oocytes (n = 20). Eighty-six good-to-excellent-quality two- to four-cell embryos were transferred surgically into the oviducts of 4 of the original oocyte donors in Trial I and 2 females in Trial II. A pregnancy occurred in 1 female in Trial II, and 3 live-born cubs were delivered by Caesarean section 107 days after embryo transfer. Of the 56 cleaved embryos cultured in vitro in Ham's F10 for 72 h, 14 (25.0%) were at the sixteen-cell stage, and 15 (26.8%) were morulae.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:In vitro fertilization and embryo development in vitro and in vivo in the tiger (Panthera tigris). 229 9

In the present study the functional and morphologic effects of two pulmoplegic solutions are evaluated. Single left-lung allotransplantation with ligation of the right pulmonary artery was performed in 15 piglets (13-20 kg). The lungs were preserved after donor prostaglandin E-1 treatment with single pulmonary artery flush with either modified Euro-Collins solution (mECS) (9 pigs) or oxygenated fluorocarbon emulsion (FC-43) (6 pigs) and transplanted after 6-hr storage in cold Physiosol solution. Tidal volumes of 15 ml/kg x fr (18) with 40% inspired oxygen were used for ventilation during reperfusion. Function of the transplanted lung was monitored for 4 hr postoperatively by determining pa CO2 and pa O2 levels from arterial samples and by noninvasive monitoring of end-tidal CO2 values and arterial oxygen saturations. Sequential morphologic changes in pulmonary artery flow surface and lung tissue were studied after 6-hr storage and 4-hr reperfusion, using light, scanning, and transmission electron microscopy (LM, SEM, TEM). There was no mortality. After transplantation the mECS group experienced significant hypoxia and hypercarbia and had low end-tidal CO2 values as signs of defective oxygenation and gas exchange, whereas the FC-43 group was normoxic and normoventilated without disturbed elimination of carbon dioxide. After storage and reperfusion, LM showed signs of increased vascular permeability and reperfusion damage--more evident in the mECS group compared with the FC-43 group--while the lymphoid cell population was more intensely activated in the latter group. Electron microscopy after storage showed good overall preservation of structures in both groups. After reperfusion preservation of pulmonary artery flow surface and lung tissue was estimated to be moderate in the mECS group, whereas it was good-to-moderate in the FC-43 group by SEM (NS). TEM of lung tissue, however, showed significantly better-preserved alveolar epithelial lining in the FC-43 group compared with the mECS group. In conclusion, oxygenated fluorocarbon (FC-43) pulmoplegia gave better functional and morphologic preservation of lung grafts compared with modified Euro-Collins solution.
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PMID:Single lung allotransplantation in pigs. A morphologic study of tissue preservation with modified Euro-Collins and fluorocarbon solutions. 236 Feb 50

Nine mongrel dogs were anesthetized, paralysed, ventilated, and placed in an iron lung. Each animal was transiently connected to a spirometer and the respiratory system compliance measured by applying negative or positive extrathoracic pressures (from -20 cm H2O to +20 cm H2O in 5 cm H2O steps). A sub-lobar bronchus was wedged with a 5.5 mm bronchoscope, and a 5f Swan-Ganz catheter was inserted into the lumen of the bronchoscope; one port served to introduce a 200 ml.min-1 flow of 5% CO2 in air, the other to measure the pressure in the wedged segment. Rcoll was measured with extrathoracic pressures in the iron lung ranging from 0 to -20 cm H2O (NEP) and 0 to +20 cm H2O (PEP) in 5 cm H2O steps, and under expiratory positive airway pressure (EPAP) of 5, 10, 15, and 20 cm H2O. The maximal changes in FRC were an increase of 1009 +/- 49 ml (mean +/- SEM) with NEP and a decrease of 397 +/- 33 ml with PEP. Increasing FRC decreased Rcoll while decreasing FRC markedly increased it. EPAP induced similar decreases in Rcoll as NEP of equal pressure. This effect of EPAP was inhibited by simultaneously applying PEP of equal pressure. We conclude that resistance to collateral flow is highly dependent on lung volume, and that positive airway pressure decreases Rcoll by its effects on lung volume.
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PMID:Effects of lung volume and positive airway pressure on collateral resistance. 236 48

We have investigated the effects of OPC-8212, a new positive inotropic agent, and dobutamine, a known cardioselective inotropic agent, on global left ventricular (LV) and ischemic regional functions in 14 excised canine hearts with a flow-limiting stenosis of the left circumflex coronary artery (LCX) (i.e., 20-25% of control flow). OPC-8212 infusion (n = 7) under LCX stenosis improved cardiac depression [i.e., peak LV dP/dt increased from 1,295 +/- 143 mm Hg/s to 2,669 +/- 266 mm Hg/s (mean +/- SEM) (p less than 0.001)], while myocardial ischemic injury, assessed by myocardial CO2-tension and electrocardiogram (ECG)-ST changes, improved (i.e., delta CO2-tension and ECG-ST deviation decreased from 21.1 +/- 3.6 mm Hg and 3.8 +/- 0.6 mV to 13.3 +/- 2.8 mm Hg (p less than 0.01) and 2.0 +/- 0.7 mV (p less than 0.05), respectively). On the other hand, dobutamine infusion (n = 7) further increased myocardial CO2-tension and ECG-ST deviation [i.e., delta CO2-tension and ECG-ST deviation increased from 14.4 +/- 4.2 mm Hg and 2.5 +/- 1.2 mV to 29.0 +/- 6.0 mm Hg (p less than 0.01) and 4.9 +/- 1.0 mV (p less than 0.01), respectively]. At the same time, peak LV dP/dt clearly improved, but to a lesser degree; from 1,425 +/- 153 mm Hg/s to 2,393 +/- 245 mm Hg/s (p less than 0.001). There was also an increase in percent systolic segment shortening of each corresponding area as with OPC-8212.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of OPC-8212, a new positive inotropic agent, and dobutamine on left ventricular global and ischemic regional functions and coronary hemodynamics under coronary artery stenosis. 241 80


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