Henriksen, Jens H.; Bendtsen, Flemming; Gerbes, Alexander L.; Christensen, Niels Juel; Ring-Larsen, Helmer; Sørensen, Thorkild I. A.
Estimated central blood volume in cirrhosis. Relationship to sympathetic nervous activity, ß-adrenergic blockade and atrial natriuretic factor.
In: Hepatology, Vol. 16: pp. 1163-1170
The estimated central blood volume (i.e., blood volume in the heart cavities, lungs and central arterial tree) was determined by multiplying cardiac output by circulatory mean transit time in 19 patients with cirrhosis and compared with sympathetic nervous activity and circulating level of atrial natriuretic factor. Arterial norepinephrine level, an index of overall sympathetic nervous activity (3.08 nmol/L in patients vs. 1.36 nmol/L in controls; p < 0.01) was negatively correlated (r = -0.54, p < 0.01) with estimated central blood volume (mean = 23 ml/kg in patients vs. 27 ml/kg in controls; p < 0.05). Similarly, renal venous norepinephrine level (an index of renal sympathetic tone; 4.26 nmol/L in patients vs. 1.78 nmol/L in controls; p < 0.01) was inversely correlated with estimated central blood volume (r = -0.53, n = 18, p < 0.02). No significant correlation could be established between arterial atrial natriuretic factor level (8.9 pmol/L in patients vs. 9.6 pmol/L in controls; not significant) and estimated central blood volume. Hemodynamic values were subsequently modified with oral propranolol (80 mg). During -adrenergic blockade, the mean estimated central blood volume was not altered significantly, except in six patients who exhibited decreases in mean arterial blood pressure (85 to 69 mm Hg; n = 6) and decreases in mean estimated central blood volume (23.2 to 20.6 ml/kg; n = 6, p < 0.05). Slight increases were observed in mean right atrial pressure (2.2 to 3.7 mm Hg; n = 14, p < 0.05); this change was positively correlated with the change in estimated central blood volume (r = 0.44, n = 14, p = 0.06). In conclusion, reduced estimated central blood volume probably unloads volume receptors and baroreceptors, thus provoking enhanced overall and renal sympathetic nervous activity and thereby contributing to increased water and salt retention in cirrhosis. During -adrenergic blockade estimated central blood volume changes correlated with alterations in preload and afterload. These findings indicate that central circulatory and arterial underfilling is a key element of the hemodynamic derangement observed in cirrhosis.