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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The changes in left ventricular (LV) dynamics induced by brief periods of ischemia (100 seconds) and subsequent reperfusion were analyzed in conscious dogs. Global LV ischemia, induced by partially occluding the left main coronary artery, reduced LV flow homogeneously and impaired LV function as reflected by decreases in LV stroke "work" (89 +/- 4% M +/- SE), systolic shortening (72 +/- 4%), velocity of shortening (56 +/- 6%), LV systolic pressure (34 +/- 5%), and dP/dt (59 +/- 6%). Regional LV ischemia, induced by occluding either the left circumflex or anterior descending coronary artery completely, reduced flow to the ischemic segment (82 +/- 3%) while decreasing segment work (96 +/- 5%), shortening (82 +/- 3%), and velocity of shortening (70 +/- 5%), with minimal depression of overall LV function. In both groups the extent of shortening was reduced more rapidly and greater (P less than 0.01) than shortening velocity. Moreover, with localized ischemia, segment work was reduced more (P less than 0.01) than shortening. With reperfusion, a transient overshoot in function above preischemic control levels was observed in both groups (global work increased by 60 +/- 12% and regional work by 28 +/- 4% above control). This overshoot was not dependent on adrenergic mechanisms, but was prevented by inhibiting reactive hyperemia. Thus myocardial ischemia induces a dissociation between extent and rate of myocardial shortening. A further dissociation between shortening and work is apparent with regional ischemia. After reperfusion there is a transient overshoot in function which appears to be dependent upon the associated reactive hyperemia.
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PMID:Initial myocardial adjustments to brief periods of ischemia and reperfusion in the conscious dog. 65 61

Pulmonary artery catheterization was performed in thirty-nine critically burned patients. Hemodynamic changes, induced by thermal injury and its therapy, were measured. Pulmonary wedge pressure was found to be a more reliable indicator of circulating volume, whereas central venous pressure was often misleading. Measurements of both pulmonary hemodynamics and cardiac output were necessary to manage patients requiring high levels of pulmonary end-expiratory pressure (PEEP). These measurements enable one to define optimum PEEP levels which provide maximum oxygen delivery to the tissues. Depressed myocardial function was seen in the early phase of the injury. In this period dopamine administration increased left ventricular stroke work index with minimal changes in filling pressures. The usefulness of dopamine in treating this early myocardial depression deserves further study. Catheter-related complications were minimal when the catheters were used for periods of three days or less.
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PMID:Pulmonary artery catheterization and thermodilution cardiac output determination in the management of critically burned patients. 66 8

The effects of a combination of etomidate (1.0 mg/kg bw) and fetanyl (0.005 mg/kh bw) on haematology, blood gases, acid-base balance and haemodynamics were investigated in 8 mongrel dogs. The only significant change in haematology was leucopenia. Blood gas values and acid-base balance initially showed a depression of respiration and a tendency to slight metabolic acid dosis. Decreased heart rate caused diminution of cardiac output, while systemic and pulmonary resistance as well as stroke volume were not altered significantly.
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PMID:[The combination of etomidate and fentanyl as a short acting and introduction anaesthesia in the dog in experimental medicine (author's transl)]. 66 71

Acute alterations in plasma bicarbonate concentration have minimal effects on intracerebral pH and cerebral blood flow, perhaps due to blood-brain barrier mechanisms. To test this hypothesis, the consequences of an acute rise in the plasma bicarbonate concentration were studied in anesthetized rats previously subjected to an acute pressure pulse in the carotid system with unilateral damage to the blood-brain barrier. In rats subjected to a "heavy" hypertensive insult, the hemisphere on the side of the lesion showed a lactic acidosis, edema, and a depression of cerebral blood flow. An increase in the plasma bicarbonate concentrations of 15--20 mEq/1 during 35 minutes provoked a marked rise in the total CO2 content of this hemisphere, and a further increase in the lactate concentration, but did not later the brain edema nor affect further the already very low cerebral blood flow. An increase in the lactate concentration and a decrease of cerebral blood flow in the "reference" hemisphere indicated that the lesion was not completely unilateral. In rats subjected to a "moderate" hypertensive insult the changes were less pronounced and statistically not significant for all the parameters. There results illustrate the importance of an intact blood-brain barrier for the maintenance of intracerebral pH in the face of acute alterations in plasma [HCO3]. The impaired cerebral blood flow after an acute hypertensive insult did not appear to be influenced by the intracerebral [HCO3].
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PMID:Effect of non-respiratory alkalosis on brain tissue and cerebral blood flow in rats with damaged blood-brain barrier. 67 46

In dogs anesthetized with chloralose-urethan on right heart bypass, left ventricular (LV) performance was assessed at constant LV stroke work before and for up to 2.5 h after crystalloid hemodilution was established. Lowering the hematocrit from 43.3 +/- 1.3% to 13.6 +/- 1.7% (SE) did not significantly change LV end-diastolic pressure (LVEDP) initially. After 80 min LVEDP increased slightly by 1.7 +/- 0.6 cmH2O (P less than 0.05) at a stroke work of 17.3 +/- 2.3 g.m. The value of dP/dt did not change significantly throughout. When LV function curves were generated by increasing cardiac output, the stroke work attained at an LVEDP of 10 cmH2O decreased with hemodilution from 23.9 +/- 3.5 to 20.8 +/- 3.9 g.m (NS). LV wall water content increased with hemodilution, from which it could be calculated that there was an 18.6% increase in LV mass. Thus, despite an increase in LV external girth demonstrated by LV circumferential gauges, it is possible that increased wall thickness due to the water gain resulted in little change or an actual decrease in LV end-diastolic volume. Thus, profound hemodilution can be attained with only slight depression of LV performance.
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PMID:Ventricular performance and myocardial water content during hemodilution in dogs. 73 64

The purpose of the study was to determine the early haemodynamic effects of injectable acebutolol and to study in parallel the changes in plasma renin activity (P.R.A.) in 11 patients, most of whom were affected with labile arterial hypertension. The haemodynamic measurements and P.R.A. determinations were carried out before and 5 and 15 mn after very slow intravenous injection of 10 mg acebutolol. The results obtained under these conditions were as follows: 1) Decrease in cardiac index (I.C.). It was particularly significant after 5 mn, since the I.C. decreased from 4.43 to 3.75 1/mm (p less than .01). It was essentially due to a decrease in heart rate, that fell from 90.45 to 77 beats/mn (p less than .001), while stroke volume changed virtually not. 2) Decrease in blood pressure, more marked on systolic blood pressure (110 mm Hg after 15 mn as against 154 mm Hg before injection; p less than .001), associated with a decrease in left ventricular work (4.7 kgm/mn/m2 after 5 mn as against 6.2 kgm/mn/m2 before injection; p less than .001), without significant changes in total systemic arterial resistances. 3) Increase in diastolic pulmonary arterial pressure (10.4 mm Hg after 5 mn against 8.09 mm Hg before injection; p less than .001), testifying to a slight left ventricular myocardial depression. 4) Decrease in supine P.R.A. level (0.72 nanogram/1/mn after 5 mn as against 1.15 nanogram/1/min before injection; p less than .01). A significant correlation was found between this decrease in P.R.A. and that in I.C., testifying to a close parallelism between the inhibition of cardiac beta-1 receptors and that of the receptors involved in renine secretion. 5) The tolerance of injectable acebutolol appeared to us to be excellent.
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PMID:[Hemodynamic effects and effects on plasma renin activity of injectable acebutolol in arterial hypertension]. 76 6

Ketamine, currently being evaluated as an obstetric anaesthetic agent, is said to provide analgesia without depression of the protective airway reflexes or depression of the respiratory or cardiovascular systems. We have studied the effects of ketamine on the uterine blood flow, the foetus and the newborn in five monkeys (Macaca nemistrina). Uterine blood flow, (UBF) was measured by the steady-state infusion technique using tritiated water as the indicator. All of the variables were measured during a control period and again at 10 and 90 min after the administration of ketamine in doses of 2 mg/kg in three monkeys or 1 mg/kg in two. Maternal respiration was maintained at normal physiological levels without significant variation. The maternal mean arterial pressure (MAP), cardiac output (CO), and stroke volume (SV) did not change significantly, but heart rate (HR) did increase significantly following the injection of ketamine and remained increased for the duration of the study. UBF, a-v oxygen difference, and the oxygen consumption of the uterus and its contents remained stable throughout. During the intrauterine period the foetus did not seem to be affected by the two doses of ketamine. However, the three newborn monkeys delivered of the mothers who had reveived ketamine 2 mg/kg had profound respiratory depression. This was not seen in the two infants delivered from mothers receiving 1 mg/kg. Others have shown that neonatal depression is dose- and time-related. We conclude that ketamine should be administered to obstetric patients in small single doses or by continuous infusion in very low concentrations.
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PMID:Respiratory depression in newborn monkeys at Caesarean section following ketamine administration. 81 Dec 35

Hemodynamic and electrocardiographic analysis during rapid right atrial stimulation was performed before and one, two, and four hours after oral application of longacting nitroglycerin (5 mg) and isosorbide dinitrate (20 mg) in 11 and 9 patients, respectively with coronary heart disease. Atrial stimulation without nitrate induced significant ischemic ST segment depression. Cardiac output showed a small decrease and the mean arterial, pulmonary artery, and pulmonary wedge pressure increased. Isosorbide dinitrate reduced the ischemic reaction by 40% from the first to the fourth hour after application. Cardiac output, stroke volume, aterial, pulmonary artery, and pulmonary wedge pressure also decreased continuously. Nitroglycerin caused a similar reduction of ischemic ST segment depression for two hours. Systolic, diastolic, and mean arterial pressure decreased significantly. Cardiac output, stroke volume, and pulmonary artery pressure remained unchanged. It was concluded that the applied dose of isosorbide dinitrate showed a more extensive longacting effect.
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PMID:[Hemodynamic and electrocardiographic prolonged nitrate effect during frequency load in coronary disease]. 82 Jan 4

The effects of an intravenous infusion of nitroglycerin were studied in 20 acutely hypertensive patients during coronary-artery surgery. Eight patients had histories of essential hypertension and six had been treated for it. They were anesthetized with morphine, diazepam, N2O, O2, pancuronium, and enflurane. Control measurements were obtained after sternotomy. Nitroglycerin was then administered until the blood pressure returned to normal, and the measurements then repeated. The mean dose of nitroglycerin was 80.0 +/- 4.7 mug/min, or 0.96 mug/kg/min. This produced significant decreases (P less than .05) in systolic, diastolic, and mean arterial blood pressures, central venous pressure, pulmonary capillary wedge pressure, systemic vascular resistance, and left ventricular stroke work index. Cardiac index, stroke index, and heart rate were unchanged. Two indices of myocardial oxygen demand (rate-pressure product and tension-time index) were significantly decreased by nitroglycerin (P less than .005). Fifty per cent of the patients had improvement in ST-segment depression on the electrocardiogram. These findings demonstrate that nitroglycerin can be safely administered intravenously during operation, and suggest that nitroglycerin decreases myocardial oxygen demand and relieves myocardial ischemia.
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PMID:Nitroglycerin infusion during coronary-artery surgery. 82 Feb 17

The effect of respiration on the cerebrovascular response to elevated intracranial pressure (ICP) was studied in anesthetized dogs. Total and regional cerebral blood flows were measured using labelled microspheres. In spontaneously breathing dogs total and regional cerebral blood flows increased when cerebral perfusion pressure was reduced to 20 mm Hg. The increase in regional flows was greater in the infratentorial areas than in the supratentorial areas. The increase in cerebral flow in spontaneously breathing dogs was associated with the development of hypoxemia and respiratory acidosis secondary to depression of ventilation. Elevation in ICP while regulating PO2, PCO2, and pH by controlled ventilation resulted in decrease in the total and regional cerebral blood flows. The decrease in regional flows was greater in the supratentorial areas. Induction of respiratory acidosis during elevated ICP in the controlled ventilated dogs with a 5% CO2 in air gas mixture, reversed the decrease in cerebral flows. The results suggest that the increase in cerebral blood flow during elevated ICP in spontaneously breathing dogs is secondary to the development of hypoxemia and respiratory acidosis since cerebral vessels retain responsiveness to increased PaCO2 when the vessels are dilated due to elevated ICP. The results also indicate that the regional cerebrovascular response to elevated ICP is non-uniform.
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PMID:Respiratory influence on the total and regional cerebral blood flow responses to intracranial hypertension. 84 90


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