Echocardiography assessment of left ventricular function in the critically ill

A modified postural drainage position produces less cardiovascular stress than a head-down position in patients with severe heart disease: A quasi-experimental study

QUESTION

Does a modified postural drainage position (horizontal) produce less cardiovascular and respiratory stress than a head-down postural drainage position (30 degrees) in people with severe heart disease?

DESIGN

A quasi-experimental study.

PARTICIPANTS

Thirty-one patients (mean age 69 years, SD 13) with severe left ventricular systolic dysfunction (mean ejection fraction 23%, SD 7) who were stable, receiving regular medication and free of acute respiratory illness.

INTERVENTION

Two manoeuvres were performed--one from long sitting to a modified (horizontal) postural drainage position, and one from long sitting to a head-down (30 degrees) postural drainage position.

OUTCOME MEASURES

Cardiovascular responses examined were blood pressure, sphygmocardiographic indices, and cardiac rhythm. Respiratory responses examined were respiratory rate, transcutaneous arterial oxyyhaemoglobin saturation, and dyspnoea.

RESULTS

Three participants were intolerant to the postural drainage positions--two during head-down and one during modified positioning. The remaining 28 participants maintained their resting cardiac rhythm and did not complain of chest pain or dyspnoea. The changes in cardiovascular responses during the sitting to head-down postural drainage manoeuvre in the tolerant participants were significantly greater (p < 0.05) than the changes during the sitting to the modified postural drainage manoeuvre for most of the sphygmocardiographic indices. In contrast, there were no significant respiratory responses to either postural drainage manoeuvre.

CONCLUSION

Modified positioning is associated with less cardiovascular stress than head-down positioning, yet for most patients with severe heart disease, both positions are generally well tolerated. For a subset of these patients, either position may be inappropriate. This suggests that modified positioning should be attempted first but that a head-down position may be attempted if the modified position proves ineffective.

Fluid therapy in sepsis with capillary leakage

Sepsis is associated with a profound intravascular fluid deficit due to vasodilatation, venous pooling and capillary leakage. Fluid therapy is aimed at restoration of intravascular volume status, haemodynamic stability and organ perfusion. Circulatory stability following fluid resuscitation is usually achieved in the septic patient at the expense of tissue oedema formation that may significantly influence vital organ function. The type of fluid therapy, crystalloid or colloid, in sepsis with capillary leakage remains an area of intensive and controversial discussion. The current understanding of the physiology of increased microvascular permeability in health and sepsis is incomplete. Furthermore, there is a lack of appropriate clinical study end-points for fluid resuscitation. This review considers critically the clinical and experimental data analysing the assessment of capillary leakage in sepsis and investigating the effects of different fluid types on increased microvascular permeability in sepsis.

Transesophageal echocardiographic (TEE) evaluation of ventricular function

Transesophageal echocardiography (TEE) provides excellent delineation of ventricular function in the ambulatory and critical settings. Major indications include the acutely ill patient with suboptimal images with other techniques and the intraoperative assessment of patients undergoing cardiac surgery and of cardiac patients undergoing noncardiac surgery. The methodology of quantification of ventricular function is quite accurate, though it has inherent limitations. Newer technologies, such as edge enhancement techniques, three-dimensional acquisition, and contrast agents, all have the potential to improve evaluation of ventricular function with TEE. Stress imaging with TEE is possible with dobutamine and with pacing techniques. This is sage and accurate, and it is indicated in patients, such as the morbidly obese, who are impossible to image by other methods.

Estimation of cardiac output by noninvasive echocardiographic techniques in the critically ill subject

We evaluated the accuracy of cardiac output estimations by three transthoracic echocardiographic techniques in critically ill subjects. This study was a prospective comparison study carried out in a general intensive care unit of a teaching hospital. The subjects had a broad range of diagnoses including pulmonary embolus, cardiogenic shock, septic shock, Legionnaire's disease and perioperative myocardial infarction. All patients requiring pulmonary artery catheterization underwent echocardiographic cardiac assessment with comparison of findings to those obtained by thermodilution techniques. Nineteen studies on eighteen patients were performed, with cardiac output calculated by the two-chamber Simpson's, four-chamber Simpson's, and left ventricular outflow tract (LVOT) Doppler methods. Acceptable data was obtained in those patients without mitral regurgitation. There was good correlation between the thermodilution technique and Simpson's two-chamber method (r = 0.91), but less so with the Simpson's four-chamber method (r = 0.77). All studies were included in the LVOT Doppler method with a good correlation (r = 0.94). A plot of differences between methods using the Bland and Altman statistical method indicated that only the LVOT Doppler method demonstrated acceptable agreement with a mean of 0.2 litres/minute, standard deviation of 0.82 litres/minute and 95% limits of agreement of -1.5 to +1.9 litres/minute. We concluded that the LVOT Doppler method was the only one which demonstrated acceptable agreement between the thermodilution method and echocardiographic techniques in all critically ill patients studied.