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

We repeatedly assessed pulmonary and systemic hemodynamics in 30 patients undergoing therapy for severe acute respiratory failure of diverse causes. Pulmonary-artery hypertension and elevated pulmonar vascular resistance were observed in all patients after correction of systemic hypoxemia. Increasing pulmonary blood flow by isoproterenol infusion or decreasing pulmonary blood flow by partial bypass of the right side of the heart minimally altered pulmonary-artery pressure. Although neither elevated pulmonary vascular resistance nor low cardiac index reliably predicted death, survivors had preogressive decreases of pulmonary vascular resistance with time, whereas nonsurvivors tended to maintain or increase pulmonary vascular resistance. Right ventricular stroke-work index was markedly elevated in all patients. The work load imposed upon the right ventricle by elevation of pulmonary vascular resistance may be a factor limiting survival in severe acute respiratory failure.
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PMID:Pulmonary hypertension in severe acute respiratory failure. 83 25

The cardiac response to volume loading was evaluated in fifty severely septic patients. After a rapid infusion of albumin or whole blood the cardiac index (CI) and left ventricular stroke work index (LVSWI) were recorded as the pulmonary arterial wedge pressure (PAWP) increased. Initial values of PAWP, CI, and LVSWI were similar in both the nineteen surviving and thirty-one nonsurviving patients. Surviving patients, however, demonstrated greater increases in CI and LVSWI as PAWP rose. Nearly half of both patient groups developed decreases in CI and LVSWI as the PAWP continued to increase. These downslopes occurred at relatively low PAWP and are taken as evidence of an abnormality of myocardial function in both survivors and nonsurvivors. The lower upslope of the performance curves in nonsurvivors indicates myocardial depression or a negative inotropic effect. Cardiac ischemia, acute respiratory failure, and high affinity red cells were found to diminish the cardiac response to volume loading, whereas hepatic and renal failure were associated with a good CI and LVSWI response.
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PMID:Myocardial depression during sepsis. 84 86

The long-term results of patients undergoing myotomy/myectomy of the ventricular septum for obstructive hypertrophic cardiomyopathy are documented in 31 patients (15 women, 16 men, age range 21 to 80 years [mean 55]) with mean New York Heart Association functional class III to IV congestive heart failure, who underwent radical myotomy/myectomy at the Brigham and Women's Hospital from 1972 to 1991. Preoperative gradients by catheterization or echocardiography ranged from 26 to 240 mm Hg (average 96). There were no operative deaths. Two patients developed early postoperative complete heart block requiring a transvenous pacemaker. Clinical follow-up was 1 to 14 years (mean 6.5). All surviving patients were restudied by echocardiography and clinical examination. The mean postoperative functional class was II. Postoperative gradients ranged from 0 to 30 mm Hg (mean 4.5) (p less than 0.001 compared with preoperative values). There were 5 late deaths (low cardiac output in 2, stroke in 2, and acute respiratory failure in 1); 4 of 5 deaths occurred in patients with concomitant coronary artery disease. Survival at 10 years was 86 +/- 9%. There were no reoperations for subaortic obstruction.
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PMID:Long-term follow-up of patients undergoing myotomy/myectomy for obstructive hypertrophic cardiomyopathy. 151 16

The possibility that an elevated pulmonary artery systolic storage volume (PASSV) correlates with improved overall ratios of ventilation-to-perfusion and hence benefits gas exchange in acute respiratory failure was examined. We examined this by assessing the correlation between PASSV and both the physiologic dead space to tidal volume ratio (VD/VT) and intrapulmonary shunt fraction (Qsp/Qt). The VD/VT and Qsp/Qt were used as an index of distribution of ventilation-to-perfusion as well as efficiency of pulmonary gas exchange. Twenty-eight patients suffering from acute respiratory failure were included. All required mechanical ventilation. PASSV was calculated from the pulmonary artery (PA) compliance and mean PA systolic distending pressure. Pulmonary arteriolar pressures were computed by Fourier analysis. PA compliance was derived from the PA time constant and the PA resistance. Storage volume fraction of stroke volume index (PASSV/SVI) was used to compare individual variations. There were inverse linear relationships between PASSV/SVI and VD/VT (r = 0.693, p less than 0.0001), and between PASSV/SVI and Qsp/Qt (r = 0.427, p = 0.012). Also, a direct correlation was found between VD/VT and PA time constant (r = 0.503, p = 0.002). The patients were divided into two groups based on PASSV/SVI to evaluate the effect of other hemodynamic data on PASSV. Comparison of the two groups revealed that VD/VT and Qsp/Qt were lower (p less than 0.0001, and p = 0.018, respectively), PA time constant was higher (p less than 0.001), and right ventricular stroke-work index was higher (p = 0.005) in the group with a high PASSV/SVI. There were no differences in other hemodynamic data between the two groups. These data suggest that an elevated PASSV may indeed benefit gas exchange in acute respiratory failure.
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PMID:Elevated pulmonary artery systolic storage volume associated with improved ventilation-to-perfusion ratios in acute respiratory failure. 164 48

Positive pressure ventilation in patients with acute respiratory failure (ARF) may render the interpretation of central venous pressure (CVP) or pulmonary wedge pressure (PCWP) difficult as indicators of circulating volume. The preload component of cardiac (CI) and stroke index (SI) is also influenced by the increased intrathoracic pressures of positive pressure ventilation. Moreover CI and SI do not indicate volume status exclusively but also contractility and afterload. We investigated whether intrathoracic blood volume (ITBV) more accurately reflects blood volume status and the resulting oxygen transport (DO2). CVP, PCWP, cardiac (CI) and stroke index (SI) were measured, oxygen transport index (DO2I) and oxygen consumption index (VO2I) were calculated in 21 ARF-patients. Ventilatory patterns were adjusted as necessary. CI, SI and intrathoracic blood volume index (ITBVI) were derived from thermal dye dilution curves which were detected with a 5 F fiberoptic thermistor femoral artery catheter and fed into a thermal-dye-computer. All data were collected in intervals of 6 h. There were 224 data sets obtained. Linear regression analysis was performed between absolute values as well as between the 6 changes (prefix delta).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Intrathoracic blood volume accurately reflects circulatory volume status in critically ill patients with mechanical ventilation. 164 59

Hemodynamic changes have been studied in 19 patients (30 observations) with acute respiratory failure of various genesis during transition from conventional controlled lung ventilation, performed using PO-6 and Phase-3C devices, to intermittent high-frequency jet ventilation ("Spiron 601"). Impedance plethysmography and rheopulmonography have been used. It has been established that intermittent high-frequency jet ventilation during 1 hour can have both positive and negative effect on systemic and pulmonary hemodynamics in patients with lung damage. It has been demonstrated that the type of reaction depends on the initial values of stroke volume and cardiac output.
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PMID:[Changes in hemodynamics during intermittent high-frequency ventilation of the lungs in patients with acute respiratory insufficiency]. 186 80

Cardiac complications comprise as much as 50% of perioperative vascular surgical morbidity and mortality. Using the Goldman multifactorial index for evaluating cardiac risk pre-operatively, 53 consecutive patients who underwent abdominal aortic aneurysm surgery were prospectively studied. Forty patients (75.5%) were also evaluated with echocardiography for assessment of left ventricular function. There were 14 (23.7%) peri-operative events, of which nine (17.0%) were acute myocardial infarctions--two of whom died (3.8%). The minor complications included three with hypovolaemic renal failure, and one each with acute respiratory failure and cerebrovascular accident. Patients with Goldman cardiac risk index (CRI) classes III and IV were associated with significantly higher risks of peri-operative complications (p less than 0.001), i.e. 77.8% and 66.7% respectively, compared with class II (22.7%) and class I (nil). Echocardiographic left ventricular shortening fraction (LVFS) of less than 28% helped identify high risk groups in all classes, although its positive predictive value was low (42.3%). Combining LVFS less than 28% with Goldman CRI categories II to IV improved the sensitivity to 91.7% and the positive predictive value to 61.1%. Careful pre-operative assessment using the simple Goldman index and echocardiography is helpful in identifying higher risk patients who would benefit from pre-operative stabilisation and more rigorous perioperative hemodynamic monitoring preferably including intensive care (ICU) management, so as to reduce cardiac complications.
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PMID:Noninvasive cardiac risk evaluation before elective abdominal aortic aneurysm surgery--clinical value of the Goldman index and echocardiography. 215 82

To examine the cyclic changes in right ventricular (RV) function induced by controlled ventilation, right heart catheterization and two-dimensional echocardiography were combined in a group of 20 patients requiring respiratory support for an episode of acute respiratory failure. Simultaneous measurements of RV pressure (using a modified pulmonary artery catheter), RV stroke output (thermodilution), and RV dimensions (two-dimensional echocardiography), permitted a beat to beat evaluation of RV function throughout the mechanical respiratory cycle. When compared with expiration, lung inflation produced an increase in RV systolic pressure and volume, an increase in RV diastolic volume with an unchanged RV diastolic pressure, and a marked decrease in RV ejection fraction. It is concluded that controlled ventilation altered RV function primarily by increasing RV afterload during the lung inflation period.
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PMID:Reevaluation of hemodynamic consequences of positive pressure ventilation: emphasis on cyclic right ventricular afterloading by mechanical lung inflation. 219 May 1

Increasing the ratio of tissue oxygen delivery (DO2) to oxygen consumption can improve the survival of critically ill patients, including those with acute respiratory failure. However, under conditions of ventilation/perfusion mismatch, the use of inotropic or vasodilator drugs to augment cardiac output could, in turn, worsen venous admixture. In a canine model of asymmetric oleic acid-induced pulmonary edema, we examined this possibility by studying the effect of 20 and 40-micrograms/kg doses of parenteral nifedipine on oxygenation variables, venous admixture, and intrapulmonary blood flow distribution. After oleic acid injury, nifedipine caused significant increases in cardiac index by 70% as systemic vascular resistance decreased proportionately by 61%. Stroke volume index (SI) and mean pulmonary arterial pressure increased, while venous admixture and the distribution of intrapulmonary blood flow did not change with nifedipine. However, nifedipine significantly improved the tissue DO2 index so that the coefficient of DO2 increased. Thus, nifedipine significantly increased SI in a dose-dependent manner, thereby improving the tissue oxygen supply-demand balance.
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PMID:Effect of nifedipine on oxygen delivery in canine asymmetric oleic acid lung injury. 236 15

The hemodynamic effects of blood volume augmentation and mechanical ventilation (MV) with positive end-expiratory pressure (PEEP) were studied in nine Beagles anesthetized with halothane before and after thrombin-induced pulmonary hypertension. The effect of therapy with dopamine, norepinephrine with and without nitroglycerin (NTG), and intraaortic balloon pumping (IABP) were studied in a second series of six Beagles. Before thrombin, dextran (35 ml.kg-1) caused a significant increase in right and left ventricular end-diastolic and end-systolic volumes (RV and LVEDV, and RV and LVESV). However, RV and LV performance, as estimated by ejection fraction, was unchanged during volume loading and MV with PEEP when the pulmonary vasculature was intact. The response to volume loading and MV with PEEP was altered significantly once PVR had been increased with the administration of thrombin. Stroke volumes were decreased, and remained so, despite volume loading and MV with PEEP. LVEDV decreased without a decrease in LVEDP, indicating a decreased LV compliance. Dopamine and norepinephrine with and without NTG increased stroke volumes and RV ejection fraction in contrast to IABP. Assessment of LV performance, according to the Frank-Starling mechanism, requires a measure of end-diastolic volume when diffuse pulmonary vasoconstriction leads to RV distension and LV hypovolemia secondary to septal shift. Measurement of LV filling pressures can provide misleading values to estimate changes in LV volume in this setting. Measurement of ventricular volumes is required for optimal management of patients with severe acute respiratory failure and pulmonary hypertension.
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PMID:Cardiovascular adjustments to pulmonary vascular injury in dogs. 312 66


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