Electrolyte and Acid-Base Disorders associated with Cancer Immunotherapy

Novel immunotherapy drugs have changed the landscape of cancer medicine. Immune checkpoint inhibitors and chimeric antigen receptor T cells are being used and investigated in almost all solid cancers. Immune-related adverse events have been associated with immunotherapies. Acute kidney injury has been the most commonly associated kidney adverse event. In this review, we showcase the several associated electrolyte disorders seen with immunotherapy. Immune checkpoint inhibitors can lead to hyponatremia by several mechanisms, with the syndrome of inappropriate antidiuresis being the most common. Endocrine causes of hyponatremia are rare. Hypokalemia is not uncommon and is associated with both proximal and distal renal tubular acidosis. Hypercalcemia associated with immune checkpoint inhibitors has led to some interesting observations including immune checkpoint inhibitor-induced parathyroid hormone - related peptide production, sarcoid-like granulomas, and hyper-progression of the disease. Hypocalcemia and hyperphosphatemia may be seen with immune checkpoint inhibitor-induced tumor lysis syndrome. Chimeric antigen receptor T cell therapy-associated electrolyte disorders are also common. This is associated chiefly with hyponatremia, although other electrolyte abnormalities can occur. Early recognition and prompt diagnosis may help providers manage the mechanistically varied and novel electrolyte disorders associated with immunotherapy.

[MODERN APPROACHES TO CORRECTION OF HYPERNATREMIA IN NEUROSURGICAL PATIENTS]

The article presents the analysis of the intensive therapy through the correction of persistent hypernatremia in neurosurgical patients after removal of brain tumors. The aim of this work was to evaluate the effectiveness of Sterofundin in the framework of complex therapy of hypernatremia in neurosurgical patients after removal of brain tumors. We analyzed the dynamics of the concentrations of sodium, potassium, chorus of the plasma, anion gap and buffer bases in the postoperative period of these patients. For obtaining reliable results, the patients were divided into groups according to the nature of the treatment: Sterofundin and symptomatic correction of hypotonic solution of sodium chloride, saluretic and Verospiron respectively. In a comparison between the groups, a distinct difference in the speed of regression of hypernatremia and durability of the achieved effect was observed. In case of treatment with Sterofundin there was a significant decrease of hypernatremia by the end of the second day of the postoperative period without tendency to re-raise. The prevalence of hypotonic solutions of sodium chloride and potassium-sparing saluretics in intensive care allowed reducing the sodium concentration non-persistently to the fourth day on the background of significant fluctuations in its concentration. The use of Sterofundin in complex therapy of electrolyte disturbances, particularly of hypernatremia in neurosurgical patients after removal of brain tumors, is reflected in the form of significant regression of increased sodium concentration in plasma compared with the method of use "hypotonic" hemodilution, saluretics and potassium-sparing diuretics.

Oral sodium and potassium binders in heart failure

Significant improvements in the morbidity and mortality associated with chronic heart failure have been gained with the use ACE inhibitors, angiotensin receptor blockers, mineralocorticoid receptor antagonists, and diuretics. However, the use of these agents is often limited by their propensity to precipitate worsening renal function and hyperkalemia, particularly in patients with chronic kidney disease. Several pharmacologic agents have been developed in recent years that utilize the gastrointestinal tract as an alternate route for drug absorption, electrolyte exchange, and drug and electrolyte elimination. The existing data establishing the safety and efficacy of these novel agents will be the focus of this review.

[Old age--neither sour nor bitter]

The development of medicine involves prolongation of human life. In many cases, however, chronic diseases, quite common in the elderly, make the quality of life very poor. We put the question: why we--the doctors--are not able to cope with the problem and whether the pharmacological treatment actually helps? A common medical practice is the use of proton pump inhibitors for various, often nonspecific disorders of the gastrointestinal tract. Statistics point to the overuse of the drugs from this group, also in the elderly. Despite the belief in the safety of such proceedings, proton pump inhibitors may pose a significant threat to older patients contributing to the symptoms worsening, and significantly affecting the mechanisms of acid-base balance. Inhibition of gastric acid secretion in the stomach is not a golden receipt in the case of dyspeptic symptoms, especially in people with the elderly. In many of them achlorhydria or hipochlorhydria is diagnosed. In others, such treatment, may not bring an expected relief in symptoms, while contributing to disturbances of acid-base balance, and--indirectly--have an adverse effect on renal function. We suggest moderation in the use of proton pump inhibitors to bring patients to a real, and not quasi wellness.

[Controversy in the treatment of acid-base abnormalities]

Sodium bicarbonate has been standard therapy for the treatment of acidosis. In lactic acidosis and hypercapnic acidosis, however, there is no clinical data supporting its effectiveness. We reviewed the literature of the efficacy of sodium bicarbonate on lactic acidosis and hypercapnic acidosis. On both conditions, we have no solid evidence supporting its beneficial effect. Conversely, acidosis or hypercapnia might be protective in acute lung and systemic organ injury. Therefore, the unprepared use of bicarbonate might be harmful in terms of fluid and sodium overload and excess lactate concentrations. According to current literature, we cannot recommend sodium bicarbonate administration for patients with lactic acidosis and hypercapnic acidosis.

[Electrolyte and acid-base balance disorders in advanced chronic kidney disease]

1. The kidneys are the key organs to maintain the balance of the different electrolytes in the body and the acid-base balance. Progressive loss of kidney function results in a number of adaptive and compensatory renal and extrarenal changes that allow homeostasis to be maintained with glomerular filtration rates in the range of 10-25 ml/min. With glomerular filtration rates below 10 ml/min, there are almost always abnormalites in the body's internal environment with clinical repercussions. 2. Water Balance Disorders: In advanced chronic kidney disease (CKD), the range of urine osmolality progressively approaches plasma osmolality and becomes isostenuric. This manifests clinically as symptoms of nocturia and polyuria, especially in tubulointerstitial kidney diseases. Water overload will result in hyponatremia and a decrease in water intake will lead to hypernatremia. Routine analyses of serum Na levels should be performed in all patients with advanced CKD (Strength of Recommendation C). Except in edematous states, a daily fluid intake of 1.5-2 liters should be recommended (Strength of Recommendation C). Hyponatremia does not usually occur with glomerular filtration rates above 10 ml/min (Strength of Recommendation B). If it occurs, an excessive intake of free water should be considered or nonosmotic release of vasopressin by stimuli such as pain, anesthetics, hypoxemia or hypovolemia, or the use of diuretics. Hypernatremia is less frequent than hyponatremia in CKD. It can occur because of the provision of hypertonic parenteral solutions, or more frequently as a consequence of osmotic diuresis due to inadequate water intake during intercurrent disease, or in some circumstance that limits access to water (obtundation, immobility). 3. Sodium Balance Disorders: In CKD, fractional excretion of sodium increases so that absolute sodium excretion is not modified until glomerular filtration rates below 15 ml/min (Strength of Recommendation B). Total body content of sodium is the main determinant of extracellular volume and therefore disturbances in sodium balance will lead to clinical situations of volume depletion or overload: Volume depletion due to renal sodium loss occurs in abrupt restrictions of salt intake in advanced CKD. It occurs more frequently in certain tubulointerstitial kidney diseases (salt losing nephropathies). Volume overload due to sodium retention can occur with glomerular filtration rates below 25 ml/min and leads to edema, arterial hypertension and heart failure. The use of diuretics in volume overload in CKD is useful to force natriuresis (Strength of Recommendation B). Thiazides have little effect in advanced CKD. Loop diuretics are effective and should be used in higher than normal doses (Strength of Recommendation B). The combination of thiazides and loop diuretics can be useful in refractory cases (Strength of Recommendation B). Weight and volume should be monitored regularly in the hospitalized patient with CKD (Strength of Recommendation C). 4. Potassium Balance Disorders: In CKD, the ability of the kidneys to excrete potassium decreases proportionally to the loss of glomerular filtration. Stimulation of aldosterone and the increase in intestinal excretion of potassium are the main adaptive mechanisms to maintain potassium homeostasis until glomerular filtration rates of 10 ml/min. The main causes of hyperkalemia in CKD are the following: Use of drugs that alter the ability of the kidneys to excrete potassium: ACEIs, ARBs, NSAIDs, aldosterone antagonists, nonselective beta-blockers, heparin, trimetoprim, calcineurin inhibitors. Determination of serum potassium two weeks after the initiation of treatment with ACEIs/ARBs is recommended (Strength of Recommendation C). Routine use of aldosterone antagonists in advanced CKD is not recommended (Strength of Recommendation C). Abrupt reduction in glomerular filtration rate: Constipation. Prolonged fasting. Metabolic acidosis. A low-potassium diet is recommended with GFR less than 20 ml/min, or GFR less than 50 ml/min if drugs that raise serum potassium are taken (Strength of Recommendation C). In the absence of symptoms or electrocardiographic abnormalities, review of medications, restriction of dietary potassium and use of oral ion exchange resins are usually sufficient therapeutic measures (Strength of Recommendation C). If symptoms and/or electrocardiographic abnormalities are present, the usual parenteral pharmacological measures should be used (10% calcium gluconate, insulin and glucose, salbutamol, resins, diuretics) (Strength of Recommendation A). Parenteral bicarbonate and ion exchange resins in enemas are not recommended as first-line treatment (Strength of Recommendation C). Hemodialysis should be considered in patients with glomerular filtration rates below 10 ml/min (Strength of Recommendation C). 5. Acid-Base Disorders in CKD: Moderate metabolic acidosis (Bic 16-20) mEq/L is common with glomerular filtration rates below 20 ml/min, and favors bone demineralization due to the release of calcium and phosphate from the bone, chronic hyperventilation, and muscular weakness and atrophy. Its treatment consists of administration of sodium bicarbonate, usually orally (0.5-1 mEq/kg/day), with the goal of achieving a serum bicarbonate level of 22-24 mmol/L (Strength of Recommendation C). Limitation of daily protein intake to less than 1 g/kg/day is also useful (Strength of Recommendation C). Use of sevelamer as a phosphate binder aggravates metabolic acidosis since it favors endogenous acid production and therefore acidosis should be monitored and corrected if it occurs (Strength of Recommendation C). Hypocalcemia should always be corrected before metabolic acidosis in CKD (Strength of Recommendation B). Metabolic acidosis is an infrequent disorder and requires exogenous alkali administration (bicarbonate, phosphate binders) or vomiting.

Acetazolamide-mediated decrease in strong ion difference accounts for the correction of metabolic alkalosis in critically ill patients

Introduction

Metabolic alkalosis is a commonly encountered acid–base derangement in the intensive care unit. Treatment with the carbonic anhydrase inhibitor acetazolamide is indicated in selected cases. According to the quantitative approach described by Stewart, correction of serum pH due to carbonic anhydrase inhibition in the proximal tubule cannot be explained by excretion of bicarbonate. Using the Stewart approach, we studied the mechanism of action of acetazolamide in critically ill patients with a metabolic alkalosis.

Methods

Fifteen consecutive intensive care unit patients with metabolic alkalosis (pH ≥ 7.48 and HCO₃^- ≥ 28 mmol/l) were treated with a single administration of 500 mg acetazolamide intravenously. Serum levels of strong ions, creatinine, lactate, weak acids, pH and partial carbon dioxide tension were measured at 0, 12, 24, 48 and 72 hours. The main strong ions in urine and pH were measured at 0, 3, 6, 12, 24, 48 and 72 hours. Strong ion difference (SID), strong ion gap, sodium–chloride effect, and the urinary SID were calculated. Data (mean ± standard error were analyzed by comparing baseline variables and time dependent changes by one way analysis of variance for repeated measures.

Results

After a single administration of acetazolamide, correction of serum pH (from 7.49 ± 0.01 to 7.46 ± 0.01; P = 0.001) was maximal at 24 hours and sustained during the period of observation. The parallel decrease in partial carbon dioxide tension was not significant (from 5.7 ± 0.2 to 5.3 ± 0.2 kPa; P = 0.08) and there was no significant change in total concentration of weak acids. Serum SID decreased significantly (from 41.5 ± 1.3 to 38.0 ± 1.0 mEq/l; P = 0.03) due to an increase in serum chloride (from 105 ± 1.2 to 110 ± 1.2 mmol/l; P < 0.0001). The decrease in serum SID was explained by a significant increase in the urinary excretion of sodium without chloride during the first 24 hours (increase in urinary SID: from 48.4 ± 15.1 to 85.3 ± 7.7; P = 0.02).

Conclusion

A single dose of acetazolamide effectively corrects metabolic alkalosis in critically ill patients by decreasing the serum SID. This effect is completely explained by the increased renal excretion ratio of sodium to chloride, resulting in an increase in serum chloride.

Equilibrium of acidifying and alkalinizing metabolic acid-base disorders in cirrhosis

BACKGROUND AND AIMS

Conflicting results exist with regard to metabolic acid-base status in liver cirrhosis, when the classic concept of acid-base analysis is applied. The influence of the common disturbances of water, electrolytes and albumin on acid-base status in cirrhosis has not been studied. The aim of this study was to clarify acid-base status in cirrhotic patients by analyzing all parameters with possible impact on acid-base equilibrium.

PATIENTS AND METHODS

Fifty stable cirrhotic patients admitted to a university hospital. Arterial acid-base status was analyzed using the principles of physical chemistry and compared with 10 healthy controls.

RESULTS

Apart from mild hypoalbuminemic alkalosis, acid-base state was normal in Child-Pugh A cirrhosis. Respiratory alkalosis was the net acid-base disorder in Child-Pugh B and C cirrhosis with a normal overall metabolic acid-base state (Base excess-1.0 (-3.6 to 1.6) vs 1.1 (-0.2 to 1.1) mmol/l, P = 0.136, compared with healthy controls, median (interquartile range)). Absence of an apparent metabolic acid-base disorder was based on an equilibrium of hypoalbuminemic alkalosis and of dilutional acidosis and hyperchloremic acidosis.

CONCLUSION

A balance of offsetting acidifying and alkalinizing metabolic acid-base disorders leaves the net metabolic acid-base status unchanged in cirrhosis.

Significance of renal function in changes in acid-base metabolism after orthotopic bladder replacement: colon neobladder compared with ileal neobladder

BACKGROUND

The objective of this study was to determine whether renal function influences the acid-base metabolism in patients undergoing orthotopic bladder replacement using intestinal segment.

METHODS

Acid-base balance, serum electrolytes and renal function were studied in 30 patients with colon neobladder and 18 patients with ileal neobladder. Mean follow up was 51 months. Effects of renal function on acid-base metabolism in both types of bladder replacement were compared. Therapeutic efficacy of the sodium bicarbonate administration was also evaluated in cases with hyperchloremic acidosis.

RESULTS

No significant differences were observed in any of the variables examined between the colon and ileal neobladder groups, except for potassium concentration. Although metabolic acidosis was detected using the Siggard-Anderson acid-base nomogram in eight (26.7%) and seven (38.9%) patients in the colon and ileal neobladder groups, respectively, this difference was not significant. In both the colon and ileal neobladder groups, the serum creatinine concentrations in patients diagnosed with metabolic acidosis were significantly higher than in those diagnosed with a normal metabolic status. Furthermore, as a result of severe metabolic acidosis, three (10.0%) and three (16.7%) patients in the colon and ileal neobladder groups, respectively, were administered sodium bicarbonate and their metabolic status was fully normalized.

CONCLUSIONS

Despite there being no statistical difference, patients with ileal neobladder may more easily develop metabolic acidosis compared with those with colon neobladder. In addition, a close association between the serum creatinine level and the degree of metabolic acidosis was observed in both groups. However, even if severe metabolic acidosis occurs, it is relatively easy to correct using sodium bicarbonate. These findings suggest that it might be safe to use a colon segment for orthotopic bladder reconstruction in patients with higher serum creatinine levels, despite no significant difference in acid-base metabolism and detection rates of metabolic acidosis between the colon and ileal neobladder groups.

Bench-to-bedside review: treating acid-base abnormalities in the intensive care unit - the role of buffers

The recognition and management of acid-base disorders is a commonplace activity for intensivists. Despite the frequency with which non-bicarbonate-losing forms of metabolic acidosis such as lactic acidosis occurs in critically ill patients, treatment is controversial. This article describes the properties of several buffering agents and reviews the evidence for their clinical efficacy. The evidence supporting and refuting attempts to correct arterial pH through the administration of currently available buffers is presented.

Critical issues in nephrology

Renal and electrolyte problems are common in patients in the ICU. Several advances that occurred in the recent past have been incorporated in the diagnosis and management of these disorders and were reviewed in this article. Unfortunately, many important questions remain unanswered, especially in the area of ARF, where new therapies are anxiously awaited to make the transition from bench to bedside. Better studies are sorely needed to define the best approach to dialysis in patients who have ARF.

[Perhydrit and sodium bicarbonate improve maternal gases and acid-base status during the second stage of labor]

Perhydrit and sodium bicarbonate were administered to 99 women during the second stage of labor. Gas analysis was done twice at the beginning and the end of the second stage. The results showed that 33 women received both perhydrit and sodium bicarbonate(Group I) had significantly higher pH, BE, pO2, and O2sat at the end of the second stage than those of 30 controls (Group III) (P < 0.05 and < 0.01). And 33 women received only sodium bicarbonate(Group II) showed merely higher pH and BE than those of Group III. The difference was significant(P < 0.05 and < 0.01), while PO2 and O2sat had no statistical difference between Group II and Group III. By comparing the values, we found that pH, PO2 and O2sat were much higher at the end of the second stage in Group I and Group II than those at the beginning of the second stage(P < 0.05 and < 0.01). No statistical difference of BE had been found between both groups. In contrary, BE, pH, PO2 and O2sat declined at the end of the second stage in Group III (P < 0.02 and < 0.01). There were no significant differences of PCO2 among the three groups. It is suggested that the administration of perhydrit and sodium bicarbonate may effectively improve the tendency of maternal metabolic acidosis and tissue oxygen debt caused by consumption and uterine contractions during the second stage, subsequently improve maternal gases and acid-base status.

Pentoxifylline improves circulatory and metabolic recovery after cardiopulmonary resuscitation

BACKGROUND

To evaluate the effectiveness of a bolus application of pentoxifylline (PTXF) at the beginning of CPR in a standardized resuscitation animal model.

METHODS AND RESULTS

In a laboratory model of cardiac arrest, 12 Wistar rats (382-413 g) were randomized into two groups. Both groups underwent 4 min of cardiopulmonary arrest induced by a transthoracic application of a fibrillating current of 10 mA. At the beginning of CPR, group one (n=6) received a bolus injection of 10 mg kg(-1) body weight PTXF versus sodium chloride in group two (controls: n=6). All animals developed a severe lactate acidosis during and after CPR but in PTXF treated animals acid-base values returned to baseline pattern. During return of spontaneous circulation (ROSC) in the PTXF group lactate concentration decreased from 13.4+/-2.1 to 1.9+/-0.7 mmol l(-1) within 60 min (P<0.01). In control animals, lactate values remained high (10.8+/-3.5 by 60 min, P<0.01). After bolus injection of PTXF pH increased from 6.93+/-0.06 to 7.29+/-0.13 within 60 min of ROSC versus 6.85+/-0.05 to 6.97+/-0.23 in sodium chloride treated animals (P<0.01). Within 5 min of ROSC, PTXF treated animals achieved higher oxygenation values (PTXF P(a)O(2)=216.9+/-62.5 mmHg, control 132. 2+/-15.1 mmHg, P<0.01).

CONCLUSIONS

Administration of PTXF at the beginning of CPR improved macrocirculation, acid-base status and arterial oxygenation.

Cardiopulmonary dysfunction during porcine endotoxin shock is effectively counteracted by the endothelin receptor antagonist bosentan

In a porcine endotoxin shock model, the mixed nonpeptide endothelin receptor antagonist bosentan was administered 2 h after onset of endotoxemia (n = 8). Cardiopulmonary vascular changes, oxygen-related variables, and plasma levels of endothelin-1-like immunoreactivity were compared with a control group that received only endotoxin (n = 8). Bosentan abolished the progressive increase in mean pulmonary artery pressure and pulmonary vascular resistance seen in controls. Possible mechanisms include blockade of vasoconstrictive endothelin receptors, and a lesser degree of edema and inflammation indicated by less alveolar protein and a lower inflammatory cell count observed in bronchoalveolar lavage. Further, bosentan restored cardiac index to the pre-endotoxin level by an increase in stroke volume index, improved systemic oxygen delivery, and acid base balance. Because mean arterial blood pressure was unaffected, bosentan reduced systemic vascular resistance. Endotoxemia resulted in an increase in tumor necrosis factor-alpha and endothelin-1-like immunoreactivity plasma levels, the latter being further increased by bosentan. In conclusion, in porcine endotoxemia, treatment with the endothelin receptor antagonist bosentan, administered during fulminate shock, abolished pulmonary hypertension and restored cardiac index. These findings suggest that bosentan could be an effective treatment for reversing a deteriorated cardiopulmonary state during septic shock.

[Correction of disturbances in acid-base status and metabolism of metabolites of the oxidative-reductive reaction in rickets]

The disturbance of redox and acid-base state in the tissues of rats with experimental rickets and in clinics has been studied. It was shown that administration of namacit for the directed correction of the disturbance of homeostasis allows decreasing the doses of vitamin D.

Effects of acid-base correction on hemodynamics, oxygen dynamics, and resuscitability in severe canine hemorrhagic shock

OBJECTIVE

To compare the effects of hypertonic saline, sodium bicarbonate, and Carbicarb resuscitation on acid-base balance, hemodynamics, and oxygen dynamics in a reperfused, canine hemorrhagic shock model.

DESIGN

Prospective, randomized trial.

SETTING

Laboratory at a university medical center.

SUBJECTS

Thirty-five anesthetized, mongrel dogs.

INTERVENTIONS

After the administration of anesthesia, the dogs were intubated and mechanically ventilated. Vascular catheters were inserted into each femoral artery, for continuous blood pressure monitoring, intermittent blood sampling, and for establishing controlled hemorrhage. A pulmonary artery catheter was inserted via the right jugular vein. Inhaled and exhaled gases were continuously analyzed using a metabolic gas monitor. The animals were subjected to 90 mins of controlled hemorrhagic shock. They were then randomly given a 2.5-mL/kg equimolar injection of 8.4% sodium bicarbonate, Carbicarb, or 5.84% hypertonic saline. The sodium load per kilogram of body weight was identical in all three groups. Thirty minutes later, the animals were retransfused with the shed blood over 15 mins and further observed for 120 mins.

MEASUREMENTS AND MAIN RESULTS

Carbicarb and sodium bicarbonate both significantly increased bicarbonate concentrations compared with saline. Arterial and venous blood pH increased more with Carbicarb than with bicarbonate but this increase was not statistically significant. After shock but before retransfusion, all three treatments moderately increased blood pressure, cardiac index, oxygen delivery index, and oxygen consumption index to a similar extent. After retransfusion, blood pressure, cardiac index, and oxygen dynamics temporarily improved in all groups, without significant improvement in the bicarbonate and Carbicarb-treated animals, despite their excellent acid-base status.

CONCLUSIONS

In severe canine hemorrhagic shock, Carbicarb, bicarbonate, and hypertonic saline appear to possess similar hemodynamic properties despite the buffering properties of bicarbonate and Carbicarb. The similar responses may be due to their identical sodium content. Arterial pH correction does not appear to further improve the responses to blood retransfusion.

Possible neuroprotective properties of flunarizine infused after asphyxia in fetal lambs are not explained by effects on cerebral blood flow or systemic blood pressure

Neuroprotective properties of the calcium channel blocker flunarizine have been reported after hypoxic-ischemic insults in immature, infant, and adult rats. However, its effect on fetal regional cerebral blood flow (rCBF) and systemic blood pressure after severe asphyxia is not known. In 15 fetal lambs (3 to 5 d after surgery; gestational age at the experiment, 123.2 +/- 2.5 d), arterial oxygen content was progressively reduced to 30% by restriction of uterine blood flow with an inflatable balloon occluder around the maternal common internal iliac artery. The rCBF was measured with radioactive microspheres at baseline condition, after 1 h of severe asphyxia, and at 30 and 120 min in the recovery phase. Immediately after the end of the occlusion period, fetuses randomly received either flunarizine or its solvent (0.5 mg/kg estimated fetal weight). No differences in rCBF changes between groups were observed during and after asphyxia. Changes in arterial blood pressure or fetal heart rate due to flunarizine could not be demonstrated either. Only five fetuses (33%) survived this degree of asphyxia longer than 24 h: four of the flunarizine-treated group and one of the control group. It is unlikely that this possible protective property of the drug is caused by its influence on rCBF, arterial blood pressure, or fetal heart rate in the phase immediately after asphyxia.

Pathophysiologic and therapeutic implications of acid-base changes during CPR

Acid-base changes occurring during cardiac arrest and subsequent CPR are related to a complex low-perfusion state characterized clinically by venous and tissue hypercarbic and metabolic (lactic) acidosis. This low-flow state is a dynamic process dependent on the time intervals between onset of arrest, initiation of CPR, and restoration of adequate spontaneous circulation. Increased release of CO2 from ischemic tissues and reduced CO2 transport from the tissues to the lungs result in profound tissue acidosis. However, recent experimental data suggest that even very low pH is compatible with neurologically intact survival. Thus, the clinical use of buffer agents, and especially of sodium bicarbonate, is currently controversial. Because results of controlled clinical studies are not available, a careful review of well-performed experimental studies is necessary. So far, the use of either CO2-generating or CO2-consuming buffers has not been proved conclusively to increase neurologically intact long-term survival after CPR. More importantly, adequate ventilation and effective chest compressions must be quickly established after cardiac arrest. This will counterbalance the hypercarbic and metabolic acidemia of cardiac arrest by creating concurrent hypocarbic arterial alkalemia during at least the early phase of CPR. Thus, the treatment of the complex acid-base changes associated with CPR is based primarily on the classical maneuvers of A and B (airway and breathing = adequate oxygenation and ventilation), C (chest compressions), and D (early defibrillation for rapid restoration of spontaneous circulation). In cases of prolonged cardiac arrest or preexisting metabolic acidemia, buffer therapy may be indicated.

[Characteristics of the dosage of sodium hydrocarbonate for correction of metabolic acidosis in surgical patients]

It has been established that in conditions of intraoperative blood and plasma loss base deficiency is determined not only by hypocarbonatemia, but also by hypoproteinemia, hypophosphatemia and HCO3 metabolism disturbances caused by anemia. Correction of metabolic acidosis in such patients should include infusions of NaHCO3, protein preparations, blood, phosphates. Mellemgaard and Astrup's technique presupposes correction of the deficiency of all buffer bases only with NaHCO3, which dramatically increases its dosage. Thus, it is evident that the technique should be revised. The comparison of the results of metabolic acidosis correction using a conventional and adapted techniques (hydrocarbonate dose in mmol or ml of a 8.4% solution is 24-SB.body weight.0.2%) in statistically homogeneous groups has shown that differentiated "polybuffer" correction of metabolic acidosis with adapted NaHCO3 dose 1.7 times more frequently normalized acid-base balance parameters, reducing the risk of the onset of post-correction metabolic alkalosis to minimum.

Disorders of acid-base balance

Acid-base disorders are common in sick children. This article is a practical guide to the differential diagnosis and treatment of simple and mixed acid-base disorders of children. Special attention is given to fundamentals of acid-base physiology, to clinical use of the Henderson equation, and to interpretation of readily available laboratory tests.

[Cardiopulmonary resuscitation: acid-base alterations and alkalizing therapy]

It is generally believed that metabolic acidosis prevails during cardiac arrest. However, recent experimental and clinical studies have demonstrated that respiratory acidosis in mixed venous blood and respiratory alkalosis in arterial blood with only minor increases in lactic acid characterize the early acid-base changes that follow cardiac arrest and cardiopulmonary resuscitation (CPR). While continued CO2 production with critical reduction in systemic perfusion explains the accumulation of CO2 in the venous side, the reduction of pulmonary blood flow with maintenance of constant minute ventilation explains the decreases in expired CO2 and therefore arterial PCO2. In the heart, marked increases in CO2 tension and lactic acid are associated with dramatic decreases in myocardial pH with consequent depression of contractile function. Administration of sodium bicarbonate, however, neither increases resuscitability nor improves long term outcome. Moreover, adverse effects stemming from increases in plasma osmolality, increases in hemoglobin-O2 affinity, induction of alkalemia and generation of CO2 are potentially deleterious for myocardial and cerebral function. Consequently, the American Heart Association has recently discouraged the routine administration of bicarbonate during the initial 10 minutes of CPR in which interventions with proven efficacy such as artificial ventilation, precordial compression, electric defibrillation and epinephrine administration take place. Alternative experimental buffer therapy with agents that consume CO2 have also failed to alter the outcome of cardiac arrest.

Effect of atrial natriuretic factor on acid-base homeostasis

Both micropuncture and clearance studies have shown that the anion excreted in the urine in response to the increased glomerular filtration rate and solute load induced by atrial natriuretic factor (ANF) depends on the pre-existing acid-base status. In normal animals, the kidney is relatively better at reabsorbing bicarbonate than chloride, as ANF increases luminal flow so that a chloruresis without bicarbonaturia ensues. In contrast, during chronic hypochloraemic metabolic alkalosis, alkalaemia renders the kidney unable to reabsorb the increment in filtered bicarbonate induced by ANF so that bicarbonaturia occurs with amelioration of the alkalosis. Since the relative magnitudes of chloride versus bicarbonate excretion rates in response to ANF are a function of the plasma anion concentrations, ANF tends to correct acid-base disorders.

Phosgene: a practitioner's viewpoint

Clinical experience with five patients exposed to phosgene is described. The treatment of phosgene poisoning was focused upon the presenting problem, pulmonary edema. Arterial hypoxemia was treated with a face mask with 10 cm CPAP with the FiO2 adjusted as needed or with a volume ventilator with controlled ventilation. Ventilation was controlled to reduce the work of breathing. Metabolic acidosis was treated with NaCHO3 to produce a normal pH. A vigorous program of diuresis was used to treat the pulmonary edema. Lasix was administered to produce a negative fluid balance while maintaining a good urinary output. The negative fluid balance correlated well with reduced oxygen requirements.

The usefulness of peripheral venous blood in estimating acid-base status in acutely ill patients

The usefulness of peripheral venous sampling in determining acid-base status in acutely ill patients was studied. A total of 171 nonarrest patients and 12 patients in cardiac arrest had paired samples of arterial and venous blood compared for correlation of blood gas results. Linear equations relating arterial and venous values of pH, PCO2, and bicarbonate were developed in both groups of patients; however, the accuracy of predicting arterial values from venous values was limited. Severe acid-base disturbances were essentially ruled out by normal or nearly normal venous blood gases. Extremely abnormal venous levels reliably reflected comparable arterial abnormalities. The results suggest that immediate intravenous bicarbonate therapy should be considered for patients with pH less than or equal to 7.05 and PCO2 less than or equal to 40 torr despite the possibility of inadvertent venous sampling. A larger series is needed to verify these results in the setting of cardiac arrest.

The effect of monoacetin and calcium chloride on acid-base balance and survival in experimental sodium fluoroacetate poisoning

Sodium fluoroacetate (compound "1080") was injected intravenously, 3 mmol/kg, to artificially-ventilated anesthetized cats. Blood pressure, ECG, acid-base parameters and serum ionized calcium were monitored in four groups of cats. Group A served as control. Group B cats were treated with calcium chloride to restore normal values of serum ionized calcium. Group C was given monoacetin (glyceryl monoacetate), 0.5 ml/kg every 30 min. Both monoacetin and calcium chloride were given to cats in group D. Fluoroacetate poisoning caused significant decrease in ionized calcium and severe metabolic acidosis with increased levels of lactate and pyruvate. The lactate to pyruvate ratio remained normal as long as there was no significant drop in blood pressure. Correction of blood ionized calcium prolonged survival from 94 to 166 min (group B). Monoacetin prolonged average survival time to 166 min. Metabolic acidosis was aggravated in monoacetin-treated animals (group C). Combined treatment with monoacetin and calcium chloride did not prolong mean survival time above 166 min.

Acid-base physiology in uremia

Chronic renal failure represents the most common disorder responsible for chronic stable metabolic acidosis. This type of metabolic acidosis has been characterized as "hyperchloremic" in pre-end-stage disease and the "anion-gap" form as the GFR falls below 20 ml/min. The early hyperchloremic, hyperkalemic variety may result from disease of the juxtaglomerular apparatus, a distal acidification defect, or volume depletion. The anion-gap acidosis of advanced renal disease occurs as a result of the inability of the diminished nephron mass to keep pace with the metabolic acid load which depletes extracellular fluid bicarbonate. Total ammonium excretion diminishes despite an adaptive increase in ammonia production per nephron. The observation that the serum bicarbonate rarely falls below 15 mEq/L and the anion gap stays below 20 mEq/L despite positive hydrogen ion balance attests to the important role of extrarenal buffers. Bone buffers, primarily calcium carbonate, titrate a portion of the excess hydrogen ions at the expense of progressive loss of bone salts. Parathyroid hormone (PTH) appears to be involved in the control of bone buffering capacity. Both PTH-dependent and PTH-independent mechanisms must therefore be considered. PTH mediates bone buffering capacity by activating intracellular shifts of calcium, phosphorus, and carbonate or by stimulation of bone carbonic anhydrase. A direct effect of pH on bone mineral mobilization has been demonstrated. Adequate alkali therapy to maintain serum bicarbonate levels of 20-22 mEq/L may prevent bone dissolution and minimize risk of volume overload.

Calculation of sodium bicarbonate requirement in metabolic acidosis

Despite the host of complications which may be associated with intravenous sodium bicarbonate infusion, the use of this agent is a frequent necessity in patients with metabolic acidosis. No satisfactory formula for calculating bicarbonate dose had previously been described, although such an approach might be expected to reduce the incidence of these complications. The authors have devised a simple formula for bedside calculation of bicarbonate requirement in metabolic acidosis, designed to elevate th pH to the region about 7.30, and report their experience with the use of this formula in 13 instances. In all but one, the post-infusion pH was between 7.25 and 7.37, with a mean of 7.30 +/- 0.04 and no instances of serious overtitration. It is concluded that the formula is useful as a pragmatic aid in the management of patients with metabolic acidosis.

Lysine hydrochloride for the control of metabolic alkalosis: a clinical report

Many physiopathological states can produce metabolic alkalosis that must be promptly corrected as soon as it is dangerous. In our study we report the effectiveness of lysine hydrochloride to correct this condition in patients. This drug lowers the pH, reduces the bicarbonate stores, and leads to normal blood gases.

[The use of oral potassium chloride (BS 560) in the treatment of mixed acid-base imbalance in patients with chronic broncho-pulmonary diseases]

The Authors, after giving an outline of metabolic alterations on acid-base balance in chronic obstructive lung disease, describe the need of correction of electrolytic umbalance, signally in relationship to metabolic alkalosis dued to hypochloremia. The Authors emphasize the importance of correction of jonic balance during long term therapy in such patients, especially diuretic and steroid long term treatment. The Authors studied the comparative effects on jonic assessment by correction with potassium chloride e.v. and potassium chloride by oral administration with a new capsulate preparation, (BS 560). Last they underline the good tolerance of this preparation and report the favourable effects on electrolytic patterns.

Acute response to acid-base stress

A method previously established in the experimental animal for predicting the acute response to either metabolic stress (bicarbonate administration) or respiratory stress(manipulation of oxygenator gas during cardiopulmonary bypass) has been extended to man. The method is based on a single nomogram. The accuracy of the nomogram is demonstrated using data from 13 patients on cardiopulmonary bypass. Similar agreement obtains between the nomogram and data reported by others. The nomogram can be used to estimate the therapeutically required dose of bicarbonate.

Complex acid-base disorders in subacute necrotizing encephalomyelopathy (Leigh's syndrome)

This report describes a case of subacute necrotizing encephalomyelopathy (Leigh's syndrome) in a 7-month-old boy. The clinical data suggest an association with a disorder of renal tubular acidification, characterized by both (proximal) type II and (distal) type I renal tubular acidosis (hybrid type). Concomitantly, the initial uncompensated metabolic acidosis evolved into a mixed metabolic acidosis and respiratory alkalosis-features of this syndrome not previously reported.

[Septic shock in the urologic patient. IV. monitoring and therapy (author's transl)]

The high mortality from septic shock in urologically ill patients can only be diminished by early diagnosis and treatment of the sepsis. However, there is no defined, steady sign from which the precise diagnosis septic shock can be established. Therefore the critical patient has to be controlled by a system that covers numerous signs that contribute to the diagnosis. Once septic shock is established its outcome depends on how early the failure of the microcirculation can be eliminated. The therapeutic approach is based on an improved cardiac output achieved by adequate volume therapy and positive inotropic drugs. For this reason the actual circulatory failure has to be defined and each therapeutic step has to be controlled using the Swan Ganz thermodilution catheter. The microcirculatory failure can be treated directly with dextran 40 and with specifically chosen vasoactive drugs. Disorders of the blood gases and base excess have to be corrected immediately. Treatment of acute renal and respiratory failure is mentioned.