Studies in edema. IV. Water retention and the antidiuretic hormone in hepatic and cardiac disease

Effect of vasopressin antagonist on water excretion in inferior vena cava constriction

Elevated levels of plasma arginine vasopressin (AVP) have been suggested to impair water excretion in congestive heart failure. In the present study, to determine a role for AVP in the impaired water excretion in rats with the inferior vena cava constriction (IVC), two AVP antagonists were used in the IVC rats at the proximal portion of the hepatic vein under the diaphragm and in sham-operated (control) rats. After surgery, 48 hrs were allowed before the experiments were started. A mean cardiac index of 260.0 +/- 12.3 ml/min/kg in the IVC rats was significantly lower than that in the control rats, 323.6 +/- 13.2 ml/min/kg (P less than 0.01). The rats were given an antidiuretic antagonist, [1-(beta-mercapto-beta, beta-cyclopentamethylenepropionic acid), 2-(O-ethyl)-D-tyrosine, 4-valine] AVP (30 micrograms/kg) or the antagonist vehicle, i.p., and 20 min later they were administered 30 ml/kg of water orally. Minimal urinary osmolality (Uosm) in the IVC rats receiving the vehicle was significantly greater than the control rats (292.7 +/- 53.1 vs. 97.8 +/- 10.6 mOsm/kg H2O, P less than 0.01). The administration of the antidiuretic antagonist in the IVC rats decreased minimal Uosm to 90.0 +/- 3.6 mOsm/kg H2O. This value was significantly lower than the vehicle rats (P less than 0.01), and was a comparable level to minimal Uosm of 82.1 +/- 3.7 mOsm/kg H2O in the control rats receiving the antidiuretic antagonist. The IVC rats excreted 51.4 +/- 5.9% of the water load in three hr, a value significantly less than that excreted by the control rats, 95.1 +/- 6.0% (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Contribution of vasopressin to vasoconstriction in patients with congestive heart failure: comparison with the renin-angiotensin system and the sympathetic nervous system

Ten patients with advanced congestive heart failure were treated with an arginine vasopressin V1 antagonist during hemodynamic monitoring to determine the contribution of vasopressin to vasoconstriction in this disorder. The vasopressin antagonist caused a decrease in systemic vascular resistance in the three patients whose plasma vasopressin was greater than 4.0 pg/ml (average for the group was 2.4 +/- 0.6). Plasma vasopressin concentration correlated with the percent decrease of systemic vascular resistance (r = 0.70, p less than 0.025), serum sodium (r = 0.72, p less than 0.02) and serum creatinine (r = 0.85, p less than 0.005). To compare the relative roles of vasopressin, the renin-angiotensin system and the sympathetic nervous system, these patients also received captopril and phentolamine. Captopril decreased systemic vascular resistance by 20% (p less than 0.05), mostly in patients with high plasma renin activity. Levels of plasma renin activity ranged between 1 and 46 ng/ml per h (average 14.7 +/- 5.7) and correlated with serum sodium (r = 0.77, p less than 0.025), serum creatinine (r = 0.73, p less than 0.025) and right atrial pressure (r = 0.67, p less than 0.05). Phentolamine decreased systemic vascular resistance in all patients (average 34%, p less than 0.01), but the decrease did not correlate with the pretreatment norepinephrine concentration. Norepinephrine levels were elevated in all patients (694 +/- 110 pg/ml) and correlated with baseline stroke volume index (r = 0.75, p less than 0.025) and plasma renin activity (r = 0.67, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Electrolyte disorders in the elderly

Normal human ageing impairs homeostatic mechanisms in such a way as to exaggerate and prolong the effects of stress. Thus, an event--pathological or traumatic--which produces a trivial change in plasma electrolytes of young people may produce major oscillations of plasma levels in the elderly, which take much longer to return to 'normal levels'. This is especially apparent with perturbations in the plasma levels of sodium and potassium, mainly due to changes in renal function and neurohumeral mechanisms which occur with increasing age. Paradoxically this does not mean that the clinician should be over-enthusiastic in attempting to correct electrolyte imbalance because, for the same reasons, the danger of over-treatment producing the opposite and equally dangerous electrolyte imbalance is ever-present. Indeed, in clinical practice most electrolyte disturbances in old age are iatrogenic in origin. Cautious patience and vigilance should be the clinical approach with elderly patients. A high index of suspicion should lead to a careful appraisal of the drug (diuretic, intravenous fluid) and environmental (dehydration) aetiology of most electrolyte disturbances in old age.

Antidiuretic hormone in congestive heart failure

In advanced heart failure, severe edema develops associated with hyponatremia. In 20 patients with severe congestive heart failure, we studied plasma antidiuretic hormone (ADH) concentrations related to hemodynamics and plasma osmolality. Prazosin was used to test the acute response to changes in atrial receptors and hemofiltration to test the response to changes in volume receptors. One group of the patients had inappropriately high ADH values (14.5 +/- 8.8 pg/ml) in relation to their plasma osmolality, which was well below normal values (276 +/- 23 mosmol/kg water) with no apparent osmoregulatory control. The other group showed a normal relationship of ADH and plasma osmolality (3.9 +/- 1.0 pg/ml; 289 +/- 8 mosmol/kg water), Only in the normal regulating group did lowering of left atrium pressure by prazosin result in a rise in ADH related to the decrease in pressure. Inappropriately high ADH secretion could be reversed by hemofiltration. This suggests that the syndrome of "dilutional hypo-osmolality" in severe congestive heart failure may be caused by an inappropriately high ADH secretion in which the osmoreceptor system is dominated by nonosmolar stimuli; however, it cannot be ruled out that associated hemodynamic effects in the kidney or other intrarenal or hormonal factors contribute to this mechanism.

Prognostic value of spontaneous hyponatremia in cirrhosis with ascites

Spontaneous hyponatremia in cirrhosis with ascites is generally considered to be due to an impaired renal ability to excrete free water, to be a contraindication of diuretics, and to be a bad prognostic sign. These concepts are reviewed in this paper. 55 cirrhotics with ascites were divided into three groups. Group I consisted of 13 patients with hyponatremia and very low free-water clearance CH2O, 0.07 +/- 0.26 ml/min). These patients also had poor renal function: low inulin clearance (CINU, 40.6 +/- 25.9 ml/min) and paraaminohippurate clearance (CPAH, 383 +/- 275 ml/min). Group II consisted of 8 patients who also had hyponatremia. CH2O, CINU, and CPAH in these patients were fairly high: 5.85 +/- 1.53 ml/min, 85.7 +/- 26.2 ml/min, and 651 +/- 294 ml/min. These values are similar to those o7 +/- 4.27 ml/min, 94.7 +/- 33.1 ml/min, and 598 +/- 199 ml/min. Hyponatremia in Group I could be related to the impaired free-water clearance. The mechanism of hyponatremia in Group II patients is not clear. Patients with hyponatremia and low CINU and CPAH had a negative response to diuretics and a poor prognosis. Patients with hyponatremia but with relatively good renal function had a good prognosis, similar to Group III patients. They responded to diuretics with no worsening of their hyponatremia.

Impaired water handling in chronic obstructive airways disease

The response to a standard water load (20 ml/kg body weight) was studied in 20 patients with chronic obstructive airways disease and in 13 healthy subjects. The percentage of the water load excreted in four hours was significantly lower in the patients (mean 51%) than in the controls (mean 106%). The maximum urine flow, osmolar clearance, free water clearance, and creatinine clearance were also significantly reduced in the patients. There was a significant inverse correlation between the percentage of load passed and the arterial PCO(2) (r = -0.798). Among the several possible causes of the reduced excretion of water which are discussed is a direct effect of hypercapnia.

Studies on water excretion following intravenous hydration and the administration of pitressin or nicotine in congestive heart failure

The diuretic response to intravenous infusions of 5 per cent glucose in water and the antidiuretic response to intravenous injections of nicotine salicylate and aqueous Pitressin, during maximal water diuresis, were studied in normal subjects and patients in congestive failure of varying severity. Patients in moderately severe congestive failure exhibited normal diuretic responses during the periods of intravenous hydration and normal antidiuretic responses following nicotine or Pitressin injections. Patients in more severe congestive failure failed to achieve comparable diuretic responses, following intravenous hydration; in the course of this, signs of increasing congestive failure developed, which were associated with further decrease in urine flows, at times, without any further decrease in renal hemodynamics. These studies confirm the impression that patients in moderate congestive failure have neither increased sensitivity to, nor reduced ability to, inactivate endogenous or exogenous antidiuretic hormone. In addition, the observation, that patients in more severe failure do not achieve adequate water diuresis during intravenous hydration, suggests that sustained production of antidiuretic production, independent of normal osmoreceptor control, may be contributing to their fluid retention.