Total exchangeable sodium, total exchangeable potassium, and total body water in edematous patients with cirrhosis of the liver and congestive heart failure

Sodium as an Important Regulator of Immunometabolism

Salt sensitivity concerns blood pressure alterations after a change in salt intake (sodium chloride). The heart is a pump, and vessels are tubes; sodium can affect both. A high salt intake increases cardiac output, promotes vascular dysfunction and capillary rarefaction, and chronically leads to increased systemic vascular resistance. More recent findings suggest that sodium also acts as an important second messenger regulating energy metabolism and cellular functions. Besides endothelial cells and fibroblasts, sodium also affects innate and adaptive immunometabolism, immune cell function, and influences certain microbes and microbiota-derived metabolites. We propose the idea that the definition of salt sensitivity should be expanded beyond high blood pressure to cellular and molecular salt sensitivity.

Challenges in diuretic therapy: A case-based discussion

Diuretics are amongst the most prescribed medications in both the inpatient and outpatient settings. They are used extensively in diverse disease states including heart failure, acute and chronic kidney disease, cirrhosis, and diseases of excess capillary permeability such as sepsis, malignancy, and malnutrition. All are characterized by total body sodium overabundance which commonly manifests as edema. The use of diuretics is however not bereft of complications. These complications frequently limit the correction of hypervolemia, resulting in continued patient suffering and frustration for the clinician. In this review, we employ a case-based approach to discuss three common challenges encountered during diuretic therapy: diuretic resistance that characterizes the nephrotic syndrome, diuretic-induced metabolic alkalosis, and diuretic-associated hyponatremia. We empower the clinician to effectively meet these challenges by providing a mechanistic understanding of these complications and their solutions.

Hyponatremia in Cirrhosis

Hyponatremia is the most common electrolyte disorder encountered in clinical practice, and it is a common complication of cirrhosis reflecting an increase in nonosmotic secretion of arginine vasopressin as a result of of the circulatory dysfunction that is characteristic of advanced liver disease. Hyponatremia in cirrhosis has been associated with poor clinical outcomes including increased risk of morbidity and mortality, poor quality of life, and heightened health care utilization. Despite this, the treatment of hyponatremia in cirrhosis remains challenging as conventional therapies such as fluid restriction are frequently ineffective. In this review, we discuss the epidemiology, clinical outcomes, pathogenesis, etiology, evaluation, and management of hyponatremia in cirrhosis.

Epithelial sodium transport and its control by aldosterone: the story of our internal environment revisited

Transcription and translation require a high concentration of potassium across the entire tree of life. The conservation of a high intracellular potassium was an absolute requirement for the evolution of life on Earth. This was achieved by the interplay of P- and V-ATPases that can set up electrochemical gradients across the cell membrane, an energetically costly process requiring the synthesis of ATP by F-ATPases. In animals, the control of an extracellular compartment was achieved by the emergence of multicellular organisms able to produce tight epithelial barriers creating a stable extracellular milieu. Finally, the adaptation to a terrestrian environment was achieved by the evolution of distinct regulatory pathways allowing salt and water conservation. In this review we emphasize the critical and dual role of Na(+)-K(+)-ATPase in the control of the ionic composition of the extracellular fluid and the renin-angiotensin-aldosterone system (RAAS) in salt and water conservation in vertebrates. The action of aldosterone on transepithelial sodium transport by activation of the epithelial sodium channel (ENaC) at the apical membrane and that of Na(+)-K(+)-ATPase at the basolateral membrane may have evolved in lungfish before the emergence of tetrapods. Finally, we discuss the implication of RAAS in the origin of the present pandemia of hypertension and its associated cardiovascular diseases.

Regional differences in osmotic behavior in brain during acute hyponatremia: an in vivo MRI-study of brain and skeletal muscle in pigs

Brain edema is suggested to be the principal mechanism underlying the symptoms in acute hyponatremia. Identification of the mechanisms responsible for global and regional cerebral water homeostasis during hyponatremia is, therefore, of utmost importance. To examine the osmotic behavior of different brain regions and muscles, in vivo-determined water content (WC) was related to plasma sodium concentration ([Na(+)]) and brain/muscle electrolyte content. Acute hyponatremia was induced with desmopressin acetate and infusion of a 2.5% glucose solution in anesthetized pigs. WC in different brain regions and skeletal muscle was estimated in vivo from T(1) maps determined by magnetic resonance imaging (MRI). WC, expressed in gram water per 100 g dry weight, increased significantly in slices of the whole brain [342(SD = 14) to 363(SD = 21)] (6%), thalamus [277(SD = 13) to 311(SD = 24)] (12%) and white matter [219(SD = 7) to 225(SD = 5)] (3%). However, the WC increase in the whole brain and white mater WC was less than expected from perfect osmotic behavior, whereas in the thalamus, the water increase was as expected. Brain sodium content was significantly reduced. Muscle WC changed passively with plasma [Na(+)]. WC determined with deuterium dilution and tissue lyophilzation correlated well with MRI-determined WC. In conclusion, acute hyponatremia induces brain and muscle edema. In the brain as a whole and in the thalamus, regulatory volume decrease (RVD) is unlikely to occur. However, RVD may, in part, explain the observed lower WC in white matter. This may play a potential role in osmotic demyelination.

Mechanisms of proximal tubule sodium transport regulation that link extracellular fluid volume and blood pressure

One-hundred years ago, Starling articulated the interdependence of renal control of circulating blood volume and effective cardiac performance. During the past 25 years, the molecular mechanisms responsible for the interdependence of blood pressure (BP), extracellular fluid volume (ECFV), the renin-angiotensin system (RAS), and sympathetic nervous system (SNS) have begun to be revealed. These variables all converge on regulation of renal proximal tubule (PT) sodium transport. The PT reabsorbs two-thirds of the filtered Na(+) and volume at baseline. This fraction is decreased when BP or perfusion pressure is increased, during a high-salt diet (elevated ECFV), and during inhibition of the production of ANG II; conversely, this fraction is increased by ANG II, SNS activation, and a low-salt diet. These variables all regulate the distribution of the Na(+)/H(+) exchanger isoform 3 (NHE3) and the Na(+)-phosphate cotransporter (NaPi2), along the apical microvilli of the PT. Natriuretic stimuli provoke the dynamic redistribution of these transporters along with associated regulators, molecular motors, and cytoskeleton-associated proteins to the base of the microvilli. The lipid raft-associated NHE3 remains at the base, and the nonraft-associated NaPi2 is endocytosed, culminating in decreased Na(+) transport and increased PT flow rate. Antinatriuretic stimuli return the same transporters and regulators to the body of the microvilli associated with an increase in transport activity and decrease in PT flow rate. In summary, ECFV and BP homeostasis are, at least in part, maintained by continuous and acute redistribution of transporter complexes up and down the PT microvilli, which affect regulation of PT sodium reabsorption in response to fluctuations in ECFV, BP, SNS, and RAS.

Transthoracic electrical bioimpedance: a non-invasive technique for the evaluation of the haemodynamic alterations in patients with liver cirrhosis

BACKGROUND/AIM

Transthoracic electrical bioimpedance is a non-invasive technique for the evaluation of systemic haemodynamics. Compared to Doppler ultrasound, it has the advantage of being operator-independent, providing continuous monitoring and being less influenced by postural changes. Until now, transthoracic electrical bioimpedance has been applied to a very limited extent in liver cirrhosis. We, therefore, aimed to compare transthoracic electrical bioimpedance and echocardiography in the assessment of haemodynamic status in cirrhotic patients.

PATIENTS/METHODS

Thirteen patients with compensated cirrhosis, 10 patients with cirrhosis and ascites and 12 controls were enrolled. Haemodynamic parameters (stroke volume, cardiac output, heart rate, mean arterial pressure and vascular peripheral resistance) were assessed simultaneously by transthoracic electrical bioimpedance monitoring with BioZ.com for at least 10 min and Doppler ultrasound.

RESULTS

The absolute mean values of haemodynamic parameters obtained by the two techniques were quite similar in all groups; furthermore, a good agreement between transthoracic electrical bioimpedance and echocardiography measurements was found for all the parameters. Finally, transthoracic electrical bioimpedance proved easy to employ and provided continuous real-time monitoring of cardio-circulatory variations.

CONCLUSIONS

The present study showed a significant correlation between transthoracic electrical bioimpedance and echocardiography in the assessment of systemic haemodynamics in patients with cirrhosis, supporting the employment of transthoracic electrical bioimpedance in pathophysiological studies requiring real-time continuous monitoring of haemodynamic parameters.

EXCHANGEABLE SODIUM, BODY POTASSIUM, AND BODY WATER IN PREVIOUSLY EDEMATOUS CARDIAC PATIENTS: EVIDENCE FOR OSMOTIC INACTIVATION OF CATION

Measurements have been made of total exchangeable sodium, total body potassium, and total body water in a group of 13 previously edematous patients with heart disease, and in 20 "control" patients. The data show that while both groups have the same quantity of water as the per cent of body weight and the same body potassium concentration, the cardiac group has an excess of exchangeable sodium when compared with the "controls." Since the excess sodium in the cardiac group cannot be attributed to the loss of potassium or the accumulation of water, the results of these studies are taken as evidence that osmotic inactivation of a considerable amount of some cation, probably sodium, has taken place. It is suggested that a likely site for cation binding is in the polyanionic constituents of the connective tissues.

Clinical relevance and management of the major electrolyte abnormalities in congestive heart failure: hyponatremia, hypokalemia, and hypomagnesemia

Electrolyte disturbances are a common complication of CHF. CHF provides a perfect milieu for the development of these disturbances; renal dysfunction, elevation of neurohormonal substances, activation of the renin-angiotensin-aldosterone axis, and diuretic therapy represent the major contributory factors. Hyponatremia is closely aligned with an unfavorable clinical course. Hypokalemia is associated with increased ventricular dysrhythmias. Hypomagnesemia noted in advanced CHF can be accompanied by arrhythmias and refractory hypokalemia. CHF also offers the ideal milieu (diseased, ischemic, and arrhythmogenic myocardium; elevated catecholamines; and arrhythmogenic drugs) for the threatening clinical consequences (clinical deterioration, dysrhythmias, or death) of these disturbances. These consequences underscore the importance of the recognition, appreciation, and management of these electrolyte abnormalities.

Renal function in patients with untreated acute myocardial infarction

This study provides data on plasma volume (PV), extracellular volume (ECV) and renal function in 8 untreated patients with acute myocardial infarction (AMI). At day 2 and day 10 after AMI, glomerular filtration rate (GFR), urinary excretion rate of water (Vu), sodium clearance (CNa) and lithium clearance (CLi) were used for assessing reabsorption rates of sodium and water in proximal and distal nephron segments. PV and blood pressure at day 2 were not significantly different from values at day 10. Heart rate (HR), weight and ECV at day 2 were significantly increased when compared with values at day 10 (78 vs. 62 pr. min and 17.0 vs. 16.2 1, respectively). Plasma norepinephrine values were slightly elevated at day 2 and day 10. GFR was initially high and decreased from day 2 to day 10 (118 vs. 104 ml min-1) together with CLi and Ck. However, Vu, CNa and fractional excretion rate of sodium increased markedly from day 2 to day 10. The results suggest that sodium and water retention in the initial phase of AMI without left ventricular failure is due to an increase in tubular reabsorption in distal nephron segments mediated by mechanisms other than the sympathetic nervous system.

Potential role of potassium as a determinant of morbidity and mortality in patients with systemic hypertension and congestive heart failure

Prehistoric animals and humans consumed a diet low in sodium but high in potassium, and thus, evolutionary forces fostered the development of physiologic systems that conserved sodium and excreted potassium. With the advent of civilized societies, food cooking and processing have greatly increased the sodium but decreased the potassium content of the diet. However, there has been little time for physiologic systems to adapt. The resulting excess of sodium has been implicated as an important factor in the development of hypertension and congestive heart failure. This traditional focus on sodium has ignored the potential role that an inadequate dietary intake of potassium might play in the degenerative diseases of the heart, brain and kidney. Yet dietary potassium may be as powerful a determinant of cardiovascular morbidity and mortality as dietary sodium. In experimental and clinical hypertension, an increased intake of potassium (without a change in dietary sodium) can reduce blood pressure, may suppress the activity of the sympathetic nervous and renin-angiotensin systems, and can prevent the development of vascular injury; conversely, potassium depletion has been associated with an increase in stroke and sudden death. In patients with chronic heart failure, potassium can modify both the mechanical and electrical properties of the heart, it can exert diuretic effects, and it can reduce the frequency and complexity of potentially lethal ventricular tachyarrhythmias. Given this central role, the effects of many pharmacologic interventions on the morbidity and mortality of patients with hypertension or chronic heart failure can be enhanced or diminished by the effect that these treatments might have on potassium homeostasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Edema of cardiac origin. Studies of body water and sodium, renal function, hemodynamic indexes, and plasma hormones in untreated congestive cardiac failure

This study provides data on plasma hormone levels in patients with severe clinical congestive cardiac failure who had never received therapy and in whom the presence of an accumulation of excess water and sodium had been established. Eight patients were studied; two had ischemic cardiac disease, and six had dilated cardiomyopathy. Mean hemodynamic measurements at rest were as follows: cardiac index, 1.8 l/min/m2; pulmonary wedge pressure, 30 mm Hg; right atrial pressure, 15 mm Hg. Total body water content was 16% above control, extracellular liquid was 33% above control, plasma volume was 34% above control, total exchangeable sodium was 37% above control, renal plasma flow was 29% of control, and glomerular filtration rate was 65% of control. Plasma norepinephrine was consistently increased (on average 6.3 times control), whereas adrenaline was unaffected. Although plasma renin activity and aldosterone varied widely, they were on average above normal (renin 9.5 times control, aldosterone 6.4 times control). Plasma atrial natriuretic peptide (14.3 times control) and growth hormone (11.5 times control) were consistently increased. Cortisol was also increased on average (1.7 times control). Vasopressin was increased only in one patient.

Renal function abnormalities, prostaglandins, and effects of nonsteroidal anti-inflammatory drugs in cirrhosis with ascites. An overview with emphasis on pathogenesis

The ability of the kidneys to excrete sodium and free water is often impaired in patients with cirrhosis. Sodium retention is a sine qua non for ascites formation. The impairment of water excretion causes hyponatremia and hypo-osmolality. In addition, these patients frequently have functional renal failure caused by intense renal vasoconstriction. The renin-angiotensin-aldosterone system and the sympathetic nervous system, which are activated in most cirrhotic patients with ascites, and a nonosmotic hypersecretion of antidiuretic hormone are important mechanisms of sodium and water retention. Angiotensin II and sympathetic nervous activity may also be involved in the pathogenesis of functional renal failure. The renal production of prostaglandins is increased in cirrhotic patients with ascites as a homeostatic response to antagonize the vascular effect of endogenous vasoconstrictors and the tubular action of antidiuretic hormone. Nonsteroidal anti-inflammatory drugs should, therefore, be administered with caution in these patients because they may induce acute renal failure and water retention. Although sulindac inhibits the renal synthesis of prostaglandins in cirrhotic patients with ascites, it appears to have less effect on renal function than do other nonsteroidal anti-inflammatory drugs administered to these patients.

Evolution, cardiac failure, and water metabolism. Presidential address

In this essay, I take the liberty of doubting the widely held view that congestive cardiac failure is due to an inability of the heart to provide enough oxygen for the needs of the body. Instead, the syndrome is best explained by an inappropriate and prolonged stimulation of the neurohumoral defense reaction that developed during evolution to support exercise and preserve life.

The role of restriction of sodium intake in the treatment of heart failure in the elderly

For the vast majority of elderly patients with chronic heart failure, clinically effective dietary sodium restriction can be achieved in a diet that remains nutritious and palatable. Obtaining a thorough diet history is the initial step in devising a low-sodium regimen. Then, the nutritionist and patient can work together to develop a dietary regimen that is culturally, economically, and medically acceptable. Although the availability of potent medications has markedly altered the medical approach to chronic congestive heart failure, their use is not without risk. Thus, dietary management continues to be a useful strategy in the treatment of this condition.

Intracellular and exchangeable potassium in cirrhosis. Evidence against the occurrence of potassium depletion in cirrhosis with ascites

The intracellular potassium content of leukocytes, the extracellular fluid volume (82Br space), and exchangeable potassium were determined in 28 patients with cirrhosis of the liver (18 with ascites) and in 15 hospitalized controls. No intracellular potassium depletion could be identified in these patients. Leukocyte potassium was similar in cirrhotic patients with and without ascites (355.9 +/- 25.3 and 348.1 +/- 31.9 mEq/kg of dry solids, respectively) and in hospitalized controls (359.7 +/- 27.4) (mean +/- SD). The extracellular fluid volume was similar in controls and cirrhotics without ascites, but markedly increased in cirrhotics with ascites. The exchangeable potassium (mEq/kg of body weight) was similar in nonascitic cirrhotics and in hospitalized controls, but significantly lower in patients with cirrhosis and ascites. However, when the estimated weight of the extracellular fluid volume was substrated from the total body weight, thus obviating the influence of the increased extracellular fluid volume of ascitic patients in the body weight, the exchangeable potassium (mEq/kg of "corrected" body weight) was similar in cirrhosis with ascites (52.9 +/- 6.7 mEq/kg), nonascitic cirrhotics (55.8 +/- 6.1 mEq/kg) and hospitalized controls (55.0 +/- 8.3 mEq/kg), and a significant correlation was obtained between the exchangeable potassium and the leukocyte potassium content. In five patients, the measurements were repeated after relieving ascites with diuretics. No change was observed in the leukocyte potassium, but exchangeable potassium (mEq/kg of body weight) increased, reaching values not significantly different from controls or nonascitic cirrhotics. The exchangeable potassium (mEq/kg of "correct" body weight) did not change. Our results strongly suggest that potassium depletion was not present in the series of cirrhotic patients studied.

[Concentration of water, sodium, and potassium in the tissues of rats with circulatory insufficiency caused by constriction of the thoracic portion of the inferior vena cava]

In edematous rats with circulatory insufficiency, the content of water and sodium in the muscle and liver rises while that of potassium declines per 1 g wet weight. The increased sodium and decreased potassium content in the tissues cannot be accounted for only by enlargement of the extracellular volume. In contrast to normal rats, the edematous ones show a negative linear correlation between the content of sodium and potassium in the muscle and liver. The total content of sodium and potassium in the tissues increases. It is assumed that part of intracellular potassium in the test tissues of rats with circulatory insufficiency is replaced by sodium. The proportion of sodium bound to structural components of the cell increases.

Relationship between endotoxaemia and protein concentration of ascites in cirrhotic patients

Endotoxaemia was investigated by the Limulus assay in 42 cirrhotic patients with ascites and in 33 without ascites. The incidence of endotoxaemia in the former group (59.5%) was significantly (P less than 0.05) higher than in the latter (36.4%). Correlation between endotoxaemia and specific gravity and concentrations of total protein, albumin, and globulin in ascitic fluid was studied in the group with ascites. The specific gravity of ascites in 25 patients with endotoxaemia was significantly greater than that in 17 patients without endotoxaemia (P less than 0.01). The concentration of total protein in patients with endotoxaemia (13.95 +/- 7.18 milligram, mean +/- SD) was nearly twice as high (P less than 0.01) as in patients without endotoxaemia (7.49 +/- 3.60 milligram). The protein content of those who showed reactions greater or equal to 2(+) in the Limulus assay (16.78 +/- 7.14 milligram) was a significantly (P less than 0.05) higher than in those with 1(+) reaction (11.26 +/- 6.33 milligram). Moreover, the concentration of albumin in patients with endotoxaemia (7.68 +/- 4.60 milligram) was more than twice that of the patients without endotoxaemia (3.39 +/- 1.58 milligram, P less than 0.01). On the other hand, globulin concentration in patients with endotoxaemia was 1.6 times that of patients without endotoxaemia (P less than 0.01). Similar differences were noted between endotoxaemic and non-endotoxaemic patients in the ascites-to-serum ratio in protein, albumin, and globulin. These results suggest that in liver cirrhosis endotoxaemia may cause an increase in protein concentrations in ascitic fluid, and that it may be a precipitating factor in the formation of ascites.

Dynamics of serum potassium change during acute respiratory alkalosis

In summary, one should be aware that hyperventilation and hypokalaemia occur frequently in the operating room under ordinary clinical conditions. An awareness of the rapidity with which these changes occur, and their extent as well as their potential hazards, should cause consideration of more aggressive attempts to maintain normocarbia and to use supplemental potassium during anaesthesia, particularly in patients with cardiac disease.

Changes in the electrolyte content of leucocytes at different clinical stages of cirrhosis

The intracellular sodium, potassium, and water content of isolated leucocytes was estimated in 47 patients with cirrhosis. The values for sodium showed a wide scatter. In patients without ascites the mean value was significantly increased but in those accumulating ascites it was normal, although often reduced in individual subjects. Reduced values were found in patients with hyponatraemia associated with end-stage cirrhosis and diuretic treatment. Changes in leucocyte water content closely followed those in sodium content. Leucocyte potassium content was normal except in patients accumulating ascites in whom it was significantly reduced, indicating whole body depletion, and this could be corrected by administration of spironolactone.

Advantages of treatment of ascites without sodium restriction and without complete removal of excess fluid

Two modifications of the standard method of treatment of ascites in chronic liver disease were investigated in three separate randomised trials involving a total of 201 patients. These modifications were (1) an unrestricted sodium intake and (2) limitation of diuresis to partial removal of ascites, to the point of relief of abdominal tension. Mean serum sodium fell significantly in all patient groups receiving the low sodium diet and did not fall in the groups given an unrestricted diet. Mean serum urea nitrogen rose significantly in the patient groups undergoing complete diuresis and did not change in the groups undergoing partial diuresis. Mean serum uric acid rose only in the groups undergoing complete diuresis. We concluded that the advantages of these two modifications of therapy of ascites were increased dietary palatability and decreased likelihood of hyponatraemia and of rise in serum urea nitrogen and uric acid. Disadvantages included dissatisfaction of patients over incomplete clearing of ascites, occasional difficulty in performing diagnostic studies because of prolonged ascites, and unsuitability of a high sodium intake in patients whose ascites is highly refractory to treatment.

Studies on the activity of the renin-angiotensin-aldosterone system (RAAS) in patients with cirrhosis of the liver

Plasma renin activity (PRA), plasma renin concentration (PRC), angiotensinogen, angiotensin II (AT II) and plasma aldosterone were determined by radioimmunoassay in 77 patients with cirrhosis of the liver [group I: with ascites, untreated (n=23); group II: patients with ascites during treatment (n=32); group III: after removal of fluids, but under further spironolactone therapy (n=10); group IV: untreated subjects without ascites (n=12)]. With the exception of decreased angiotensinogen values in all groups ranging between 39% (group IV) and 73% (group III) no significant changes of the other parameters of the RAAS were found in untreated patients. A highly significant increase of PRA, PRC, AT II and plasma aldosterone was observed in treated cirrhotics with (group II) or without (group III) ascites. In the total series of patients AT II was closely related to PRA, PRC and aldosterone emphasizing aldosterone secretion. Plasma sodium was inversely correlated to PRA, PRC, AT II and aldosterone, but no relationship was detected between these parameters of the RAAS and plasma potassium. Our results indicate that hyperaldosteronism in cirrhosis appears unlikely to be the major determinant of avid renal sodium retention and ascites formation. An increased activity of the RAAS is most often initiated by therapeutic factors and/or markedly altered electrolyte metabolism. Therefore, basal conditions of the patients to be studied must be well defined to exclude any artificially induced stimulation of the RAAS.

Potassium depletion in heart failure and its relation to long-term treatment with diuretics: a review of the literature

There have been many studies which suggest that patients with heart failure were potassium depleted. This depletion has been attributed to the use of potent diuretics, and these are now given with either potassium supplements or potassium-retaining diuretics. A detailed examination of the studies suggests that the reported decrease in body potassium compared with the results in healthy persons is not due to the diuretics. It can be partly explained by a failure to match patients and controls in terms of age, and the remaining difference can be explained by muscle wasting. There is therefore no evidence of a potassium depletion in these patients with heart failure.

Hepatic complications

Hepatic dysfunction is one of the most common complications following major surgical intervention, and it presents a wide spectrum of clinical manifestations as discussed. Recent progress in hepatology has provided better knowledge in etiology and pathophysiology of hepatic dysfunction and its sequelae. In addition, modern medical technology has made the diagnosis of liver disease easier and more precise. Underlying liver disease should be disclosed precisely prior to surgery and surgical complication minimized for patients with hepatic impairment. If hepatic complications occur following surgical intervention, the most logical etiology and pathophysiologic explanation should be found, utilizing all the clinical and laboratory data and diagnostic procedures in order to institute proper treatment. Specific complications in hepatic surgery are also discussed. A good understanding of pathophysiologic alterations following hepatic surgery is mandatory together with detailed anatomic knowledge and surgical skill in order to prevent and to treat serious complications.

Effect of long-term diuretic treatment on body-potassium in heart-disease

Plasma and total body potassium have been measured in 151 patients with chronic heart-disease, 83 of whom were taking diuretics and potassium supplements. After allowance for age and body-size, the deficit in total body-potassium was only 3-5% (100-150 mmol) in the diuretic group. 13 of the 83 patients taking diuretic had hypokalaemia (less than 3-5 mmol/1) but the potassium deficit was no greater than in the patients with normal plasma-potassium. There was no relation between the dose of potassium supplements and either the plasma-potassium or the total body-potasium. It is suggested that potassium depletion is not a major problem in patients with heart-failure treated with diuretics. The dose of potassium supplements should therefore be determined entirely by the plasma-potassium.

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.

Hepatorenal syndrome: a disease mediated by the intrarenal action of renin

The functional renal failure accompanying advanced liver disease is characterized by azotemia, a urine of very low sodium concentration and systemic hypotension with decreased renal perfusion and high renal vascular resistance. Patients with this disorder have a markedly reduced ability to excrete free water and develop hyponatremia, ascites and edema. It is postulated that this renal dysfunction is due to hepatic failure to make renin substrate. Renin released from the kidney is thus unable to exert its pressor effect. The resultant hypotension and renal hypoperfusion continue to stimulate excessive synthesis and release of renin. It is postulated that the overdriven renal renin system increases renovascular resistance at the level of the glomerular arterioles. This causes decreased renal blood flow and decreased glomerular filtration rate leading to salt and water retention and azotemia. Since no renin substrate is available for human infusion, this hypothesis could be tested either by infusion of angiotensin II to restore systemic blood pressure and renal perfusion or by beta adrenergic blockade with propranolol to attempt to decrease the intrarenal effects of renin, restore glomerular blood flow and filtration and thus return of renal function.

Potassium depletion in severe heart disease

Exchangeable sodium and potassium, total body water, and sulphate space were measured in 42 patients with severe valvular heart disease who were free of oedema. Compared with normal subjects of the same height, no increase in exchangeable sodium was found but a mean potassium depletion of 27% was shown. This depletion was not related to diuretic therapy, and no relationship between the degree of depletion and postoperative arrhythmias was found. It is concluded that the major cause of the low exchangeable potassium is the reduction in cell mass that occurs in chronic heart disease, and that there is no significant fall in the intracellular potassium concentration.