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 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intraoperative isovolemic hemodilution might increase blood flow and tissue oxygenation in the periphery but there is concern that acute anemia may have deleterious effects on myocardium in patients with coronary artery disease. This study investigates the effects of intraoperative isovolemic hemodilution on morbidity, mortality and hemodynamics in 32 patients with significant cardiovascular disease undergoing elective abdominal aortic aneurysmectomy. The average hematocrit was lowered intraoperatively from 43% to 31% by withdrawing blood and replacing volumes with 1:3 Ringer's lactate. In ten patients myocardial function was evaluated during aortic cross-clamping and declamping in the face of hemodilution. There were two deaths: one myocardial infarction and one multiple organ failure. Aortic cross clamping did not change heart rate, vascular pressures (VP), vascular resistance (SVR), cardiac output (CO), and left ventricular stroke work (LVSW). Following declamping, VP, CO and LVSW decreased and SVR increased momentarily (p less than 0.05), but the myocardial function did not change. Isovolemic hemodilution had no apparent adverse effects on morbidity, mortality and cardiovascular performance in these patients.
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PMID:Effects of isovolemic hemodilution on abdominal aortic aneurysmectomy in high risk patients. 350 89

We studied the effects of anemia and ouabain administration on cardiac function, oxygen physiology, and blood catecholamine levels in nine newborn lambs. We measured oxygen consumption continuously, along with traditional hemodynamic variables. Oxygen transport was calculated. Following baseline measurements, lambs were made anemic (mean hematocrit = 12%) by isovolemic exchange transfusion with Plasmanate, and measurements were repeated. Thereafter ouabain was administered as a 75 micrograms/kg bolus, followed by 30 min of infusion at a rate of 0.05 microgram/kg/min. Measurements were repeated at the conclusion of infusion. Anemia was associated with a heart rate related rise in left ventricular rate of pressure rise, a rise in oxygen consumption, an increase in cardiac output, a decrease in systemic vascular resistance, and a rise in fractional oxygen extraction (oxygen consumption/transport). Following ouabain administration, cardiac output, oxygen consumption, and stroke work fell, but left ventricular rate of pressure rise and the extraction ratio did not change. Serum levels of epinephrine and norepinephrine rose with sustained anemia and ouabain infusion. In this setting, ouabain effects are manifested primarily by alterations in oxygen transport and metabolism rather than by changes in traditional assessments of left ventricular contractile function.
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PMID:Ouabain effects on oxygen physiology in anemic lambs. 358 80

Skeletal muscle ventricles (SMVs) were constructed from preconditioned latissimus dorsi muscles in eight dogs and then connected to each animal's systemic arterial circulation in short-term experiments. The lengths of time that SMVs could produce hemodynamic work as left ventricular assist devices were recorded. After 4 hr of continuous pumping at approximately 55 beats/min, six of eight SMVs were able to generate systolic pressures of 128 +/- 23 mm Hg and flows of 340 +/- 31 ml/min, representing 20 +/- 4% of the animals' cardiac output. After 8 hr of continuous pumping, five of the eight SMVs generated pressures of 110 +/- 15 mm Hg and flows of 308 +/- 88 ml/min, or 15 +/- 7% of the animals' cardiac output. The stroke work produced by the SMVs was intermediate between that of the animals' left and right ventricles. Although the SMVs were stimulated to contract at only about one-third the heart rate, the power output of the SMVs approximated that of the right ventricles because of the greater stroke work of the SMVs. Two SMVs functioned as LVADs for 14 hr. Deterioration in SMV function eventually occurred. In each case, however, complications such as anemia, hypoxia, and hypotension, which are inherent to prolonged short-term experiments of this type, contributed to the deterioration of SMV function. The results presented here suggest that skeletal muscle has the potential to directly support the circulation; however, the length of time such muscle pumps are capable of functioning has yet to be determined.
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PMID:Power output of skeletal muscle ventricles in circulation: short-term studies. 359 64

Ten homozygous sickle cell patients, aged from 4 to 20 years, underwent a periodic red blood cells transfusion program. Indications were = one stroke or more in 4 cases, repeated severe painful crisis in 2 cases, and for others = chronic anaemia induced by hypersplenism, priapism, chronic leg ulceration, dwarfism with delayed sexual maturation. Transfusion program lasted from 6 months to 6 years. In 7 cases, a phlebotomy preceded the transfusion by the same venipuncture in order to reduce the inevitable iron overload progression. Clinical benefit was clear in the following cases: lack of painful crisis with return to school, leg ulceration healing, growth and weight increase, onset of puberty. Benefit is more difficult to assess in the other observations and, particularly, in stroke. No red cell antibodies were found. An HIV contamination occurred in 3 children. All transfused patients during a period exceeding one year developed iron overload, needing a daily chelation by intramuscular deferoxamine in two of them.
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PMID:[Long-term blood transfusion in sickle-cell anemia]. 361 65

While deficient exercise performance of sick children results from hypoactivity and detraining, it can also be caused by specific pathophysiological factors. These can affect one or more components of physical fitness. A low maximal aerobic power will result from a low maximal stroke volume, as in aortic stenosis or cardiomyopathy; a low maximal heart rate, as in congenital complete heart block or intake of beta-blockers; a low O2 content of the arterial blood, as in anemia or advanced cystic fibrosis; and a high O2 content of mixed-venous blood, as in muscle atrophy or severe malnutrition. A high O2 cost of locomotion, as in advanced obesity or cerebral palsy, will cause the patient to exert at a high percentage of his maximal aerobic power and thus fatigue easily. A subnormal muscle strength, as in progressive muscular dystrophy or juvenile rheumatoid arthritis, is sometimes the primary factor that limits the walking ability or other daily functions. Recent data suggest that local muscle endurance, as assessed by the Wingate anaerobic test, is particularly deficient in some neuromuscular diseases. Examples are muscular dystrophies and spastic cerebral palsy. The ratio of peak anaerobic power to peak aerobic power seems lower in such patients than in able-bodied controls.
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PMID:Pathophysiological factors which limit the exercise capacity of the sick child. 372 7

The development of perfluorocarbon (PFC) solutions as clinically useful oxygen-carrying agents has been a slow process because PFC is immiscible in aqueous solutions, including blood. Therefore, it has been necessary to develop emulsions for IV infusions. One such emulsion (fluosol) has been the most extensively studied and has been clinically tested. It has been shown that fluosol can transport oxygen in vivo when very high inspired oxygen concentrations are used and when high arterial oxygen tensions are achieved. Furthermore, it appears that the oxygen dissolved in PFC is very effectively delivered to and used by the tissues. In severely anemic patients, the PFC may deliver a very significant portion of the total consumed oxygen. It has been difficult to prove, however, whether fluosol has been clinically beneficial. It has a limited half-life (13 hours), the amounts infused have been quite limited, and the effect on patient outcome is unclear. Further, a number of adverse effects have been related to fluosol administration, most likely related to the emulsifying agent. PFC solutions thus remain experimental. Their greatest future use may be not as a blood substitute for treatment of anemia, but rather as an agent to improve microcirculatory oxygen delivery for treatment of ischemic tissues (ie, in stroke, myocardial infarction, burns, ischemic extremities). Further development of PFC emulsions is ongoing.
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PMID:Perfluorocarbons as blood substitutes. 377 15

One hundred twenty-one patients were identified who presented to an emergency room with the complaint of dizziness. Peripheral vestibular disease (24 percent of patients) was the most common cause of dizziness, but the cause remained unknown at follow-up after six months in 37 percent of the patients. The history and physical examination were sufficient for diagnosis in 83 percent of patients in whom a diagnosis could be made. Diagnostic tests, such as complete blood counts (four patients) and chest roentgenograms (four patients), provided crucial information in some cases. At the time of follow-up, 7 percent of patients had suffered either major morbidity or had died as a result of the cause of the index episode of dizziness. Patients with an initial diagnosis of anemia, stroke, or diabetes represented a high-risk (50 percent) group for a poor outcome. However, patients who were aged under 50 years or whose dizziness was due to peripheral vestibular disease, vasovagal or psychogenic cause, drugs, or infection formed a low-risk (2 percent) group.
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PMID:Evaluation and outcome of the dizzy patient. 387 27

Cardiac performance was assessed by left ventricular catheterization in ten insulin-dependent diabetics with non-dialysis-requiring uremia. None of the patients had a history or clinical signs of ischemic or valvular heart disease or congestive heart failure. Cardiac output at rest was normal in all patients. During exercise, one patient had somewhat low cardiac output and nine showed impaired ability to increase stroke work. This impairment was accompanied by elevation of the left ventricular end-diastolic pressure. The abnormal cardiac performance could not be ascribed to the degree of anemia or uremia or to volume overload. Arterial hypertension possibly contributed. The observations suggest that in diabetic patients with moderate uremia there is also left ventricular dysfunction. Renal transplantation should therefore be considered for these patients earlier than is customary for uremics without diabetes.
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PMID:Hemodynamics in diabetic renal failure. 405 May 55

1. The optimal conditions for the development of hypertension after total nephrectomy were defined in the rat. Under these conditions, haemodynamic changes were then studied before and for 3 days after total nephrectomy in the unanaesthetized animal and compared with mock-nephrectomized controls.2. Changes in cardiac output were followed with an electromagnetic flowmeter chronically implanted on the ascending aorta, and mean arterial pressure with an indwelling aortic cannula.3. Haematocrit fell in animals developing hypertension, due to plasma volume expansion. Restriction of administered saline did not reduce the fall in haematocrit without also preventing development of the hypertension.4. Cardiac output and stroke volume increased significantly on the second and third days after nephrectomy. Peripheral resistance remained unchanged and pulse rate tended to fall.5. The increase in cardiac output appeared to be more than could be accounted for by anaemia alone, and it is suggested that plasma volume expansion was partly responsible.6. In another group of rats developing renoprival hypertension a correlation was found between changes in plasma volume and arterial pressure over the three days.7. Renoprival hypertension was accompanied by a slight but significant reduction in oxygen consumption in comparison with the controls.8. No relationship was found between the changes in blood pressure, and plasma sodium and potassium levels.9. It is concluded that the observed rise in cardiac output associated with renoprival hypertension as induced in this study was not attributable to anaemia nor to a rise in metabolic rate. The implications of this situation are discussed in relation to a theory of the pathogenesis of hypertension and the findings of other workers.
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PMID:Haemodynamic and other studies in the renoprival hypertensive rat. 550 Jul 86

In 16 patients on chronic hemodialysis, the cardiac catheterization was performed. They had received the hemodialytic treatment for 41 months in the average. All but two cases had cardiothoracic ratio above 50%. It was 58 +/- 7% in all. The laboratory data, body weight, or the interdialytic body weight change was comparable with those of other patients with normal heart size. Pericardial effusion was denied by echocardiographic study. Cardiac index and the left ventricular stroke work index were higher than normal; 4.7 L/min/m2, and 85 +/- 31 g.m/m2 respectively. Cardiac index was higher than 3.9 L/min/m2 in 11 patients and left ventricular stroke work index was above 68 g.m/m2 (= mean value of control). The pulmonary artery wedge pressure was 16 +/- 6 mmHg and abnormally high in six patients (greater than 15 mmHg). The pulmonary artery wedge pressure was found to be correlated with the cardiac work (r = 0.53, p less than 0.02), and with the cardiothoracic ratio (r = 0.64, po less than 0.02). The present study revealed a circulatory abnormality of pulmonary congestion which may be brought by an excessive load upon the heart in the renal failure patients A further increase in the cardiac work by aggravation of anemia, retention of body fluid, or the elevation of blood pressure may easily result in an acute pulmonary edema. The reduction of the load by vasodilator may be useful for the relief of the acute rise of the pulmonary artery wedge pressure as suggested in the study of a small group in the present paper.
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PMID:Circulatory state of patients on chronic hemodialysis. 645 44


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