The structural complexity of the right ventricle has made quantitative evaluation difficult. Conventional cross-sectional echocardiographic methods are limited by geometric assumptions and the position of the planes used for imaging. Previous reports have demonstrated accurate three-dimensional echocardiographic quantitation of the right ventricle in-vitro and in experimental animals. We adapted a previously described method for three-dimensional reconstruction of the left ventricle to compute right ventricular volume and ejection fraction in a clinical setting.

We examined 29 patients aged from 2 to 42 years with pulmonary hypertension, by three-dimensional echocardiography and resonance imaging. Correlation and agreement were calculated for volumes and ejection fractions. Three-dimensional echocardiographic reconstruction, when compared to resonance imaging, yielded r values of 0.95 and 0.93, and mean differences (bias) of 31% ± 19% and 33% ± 18%, for systolic and diastolic volumes respectively. Interobserver variability was low (12.9% and 8.0%). Ejection fraction as calculated by three-dimensional echocardiography showed close agreement with resonance images (bias=l% ±7%). Three dimensional echocardiography is now a method of measuring right ventricular ejection fraction in the clinical setting which produces results comparable to those of resonance imaging. Volume measurements correlated well for systole and diastole, but consistently underestimated values produced from resonance images.

Summary

Background and objective: Cardiopulmonary bypass is associated with changes of intra- and extravascular volume status often resulting in cardiopulmonary dysfunction. The purpose of this prospective double-blind study was to evaluate the influence of different priming solutions of the extracorporeal circuit on intra- and extravascular volume status and haemodynamics in patients undergoing elective mitral valve replacement. Methods: Twenty-two patients with mitral valve insufficiency were randomly allocated into two equal groups. In Group 1 cardiopulmonary bypass was primed with a nearly isooncotic solution consisting of 4% albumin. The second group received a pure crystalloid priming solution. The thermo-dye indicator dilution technique was used for the assessment of cardiac output, central and pulmonary blood volume, right ventricular end-diastolic volume and total blood volume. Results: Patients in the crystalloid group showed increased intraoperative fluid requirements. Significantly more fluid was accumulated in the extravascular space whereas total blood volume was decreased after surgery. Stroke volume index (SVI) was significantly decreased in the immediate postoperative period when compared to baseline. As indicated by the increase in extravascular fluid content after surgery, both colloid and crystalloid priming volumes were transferred to the extravascular space. Conclusion: The use of colloid priming solutions in patients with mitral valve insufficiency leads to less fluid requirements and significantly reduced fluid shift in the interstitium. However, these changes are not associated with changes in haemodynamic parameters or short term outcome.

Background and objective: The arterial thermodilution technique offers the ability to measure cardiac output using only central venous and arterial catheters. However, the technique has been reported to overestimate cardiac output because of a higher loss of cold indicator due to the increased distance between the sites of injection and measurement. In this study, the two techniques were compared with respect to conditions of low cardiac output in which a longer passage time may further increase loss of indicator.

Methods: Seventeen anaesthetized dogs were studied during hypovolaemic shock and fluid resuscitation. Cardiac output measurements were carried out simultaneously by arterial and pulmonary artery thermodilution techniques.

Results: One-hundred-and-two measurements were performed. The mean cardiac output was 2.28 ± 1.4 L min−1 by the pulmonary arterial technique and 2.29 ± 1.56 L min−1 by the arterial thermodilution technique. The correlation coefficient between the two measurements was 0.95, the precision −0.04 ± 0.41 L min−1 and the limits of agreement from −0.86 to 0.78 L min−1. The agreement was also consistent at low cardiac outputs.

Conclusions: The arterial thermodilution technique may serve as a less invasive cardiac output monitor in conditions of severe bleeding and shock.

Background and objective Despite the fact that both general anaesthetics and hypotensive drugs influence autonomic nervous activity, no study has yet examined the heart rate variability during deliberate hypotension and general anaesthesia. The aim of this was to clarify the heart rate variability changes during deliberate hypotension under sevoflurane–nitrous oxide anaesthesia.

Methods Autonomic nervous system activity in patients (n = 45) subjected to deliberate hypotension during sevoflurane in nitrous oxide and oxygen anaesthesia was investigated by a heart rate variability measurement. Three different types of hypotensive drugs, a calcium channel antagonist (nicardipine), a nitric oxide donor (nitroglycerin) and a vasodilatory prostaglandin (alprostadil), were used to induce hypotension.

Results In all groups, low frequency power (sympathetic and parasympathetic indicator) and the ratio of low frequency to high frequency power (the LF/HF ratio, sympathetic indicator) were suppressed by induction of anaesthesia. In the control group, preanaesthesia low frequency power was 195 ± 139 ms2, the LF/HF ratio 10.3 ± 5.7, during anaesthesia 5 ± 9 ms2, 0.6 ± 0.8, respectively, P = 0.0093, 0.0034, whereas high frequency power (parasympathetic indicator) was not significantly changed. In those patients receiving nicardipine or nitroglycerin during anaesthesia, these variables did not differ significantly from those in the control group. During prostaglandin E1 infusion, high frequency power was higher compared with the values in the other groups (17 ± 12 ms2 in the prostaglandin group, 7 ± 6 ms2 in the nicardipine group, 6 ± 5 ms2 in the nitroglycerin group and 6 ± 4 ms2 in the control group, respectively, P = 0.0326, 0.0251, 0.0197).

Conclusions Sevoflurane in nitrous oxide and oxygen anaesthesia reduces sympathetic autonomic activity considerably, and the expected increases caused by hypotensive agents that occur in awake volunteers were not seen.