Haemodynamic and metabolic effects in diabetic ketoacidosis in rats of treatment with sodium bicarbonate or a mixture of sodium bicarbonate and sodium carbonate

Lactic Acidosis and the Role of Sodium Bicarbonate: A Narrative Opinion

Lactic acidosis occurs commonly and can be a marker of significant physiologic derangements. However what an elevated lactate level and acidemia connotes and what should be done about it is subject to inconsistent interpretations. This review examines the varied etiologies of lactic acidosis, the physiologic consequences, and the known effects of its treatment with sodium bicarbonate. Lactic acidosis is often assumed to be a marker of hypoperfusion, but it can also result from medications, organ dysfunction, and sepsis even in the absence of malperfusion. Acidemia causes deleterious effects in almost every organ system, but it can also have positive effects, increasing localized blood flow and oxygen delivery, as well as providing protection against hypoxic cellular injury. The use of sodium bicarbonate to correct severe acidemia may be tempting to clinicians, but previous studies have failed to show improved patient outcomes following bicarbonate administration. Bicarbonate use is known to decrease vasomotor tone, decrease myocardial contractility, and induce intracellular acidosis. This suggests that mild to moderate acidemia does not require correction. Most recently, a randomized control trial found a survival benefit in a subgroup of critically ill patients with serum pH levels <7.2 with concomitant acute kidney injury. There is no known benefit of correcting serum pH levels ≥ 7.2, and sparse evidence supports bicarbonate use <7.2. If administered, bicarbonate is best given as a slow IV infusion in the setting of adequate ventilation and calcium replacement to mitigate its untoward effects.

Bicarbonate Therapy for Critically Ill Patients with Metabolic Acidosis: A Systematic Review

The management of acid-base disorders always calls for precise diagnosis and treatment of the underlying disease. Sometimes additional means are necessary to combat systemic acidity itself. In this systematic review, we discuss the concept and some specific aspects of bicarbonate therapy for critically ill patients with metabolic acidosis (i.e., patients with blood pH < 7.35). We conducted a systematic literature review of three online databases (PubMed, Google Scholar, and Cochrane) in November 2018 to validate usage of bicarbonate therapy for critically ill patients with metabolic acidosis. Twelve trials and case series were included in the final analysis, from which we assessed population, intervention, comparison, and outcome data. The current literature suggests limited benefit from bicarbonate therapy for patients with severe metabolic acidosis (pH < 7.1 and bicarbonate < 6 mEq/L). However, bicarbonate therapy does yield improvement in survival for patients with accompanying acute kidney injury.

Acid-base alterations in ESRD and effects of hemodialysis

Acid-base alterations in patients with kidney failure and on hemodialysis (HD) treatment contribute to (1) intradialytic hypercapnia and hypoxia, (2) hemodynamic instability and cardiac arrhythmia, (3) systemic inflammation, and (4) a number of associated electrolyte alterations including potentiating effects of hypokalemia, hypocalcemia and, chronically, soft-tissue and vascular calcification, imparting poor prognosis and mortality. This paper discusses acid-base regulation and pathogenesis of dysregulation in patients with kidney failure. Major organ and systemic effects of acid-base perturbations with a specific focus on kidney failure patients on HD are emphasized, and potential mitigating strategies proposed. The high rate of HD-related complications, specifically those that can be accounted for by rapid and steep acid-base perturbations imposed by HD treatment, attests to the pressing need for investigations to establish a better dialysis regimen.

Myocardial bioenergetic abnormalities in experimental uremia

Purpose

Cardiac bioenergetics are known to be abnormal in experimental uremia as exemplified by a reduced phosphocreatine (PCr)/adenosine triphosphate (ATP) ratio. However, the progression of these bioenergetic changes during the development of uremia still requires further study and was therefore investigated at baseline, 4 weeks and 8 weeks after partial nephrectomy (PNx).

Methods

A two-stage PNx uremia model in male Wistar rats was used to explore in vivo cardiac and skeletal muscles’ bioenergetic changes over time. High-energy phosphate nucleotides were determined by phosphorus-31 nuclear magnetic resonance (³¹P-NMR) and capillary zone electrophoresis.

Results

³¹P-NMR spectroscopy revealed lower PCr/ATP ratios in PNx hearts compared to sham (SH)-operated animals 4 weeks after PNx (median values given ± SD, 0.64±0.16 PNx, 1.13±0.31 SH, P<0.02). However, 8 weeks after PNx, the same ratio was more comparable between the two groups (0.84±0.15 PNx, 1.04±0.44 SH, P= not significant), suggestive of an adaptive mechanism. When 8-week hearts were prestressed with dobutamine, the PCr/ATP ratio was again lower in the PNx group (1.08±0.36 PNx, 1.55±0.38 SH, P<0.02), indicating a reduced energy reserve during the progression of uremic heart disease. ³¹P-NMR data were confirmed by capillary zone electrophoresis, and the changes in myocardial bioenergetics were replicated in the skeletal muscle.

Conclusion

This study provides evidence of the changes that occur in myocardial energetics in experimental uremia and highlights how skeletal muscle bioenergetics mirror those found in the cardiac tissue and so might potentially serve as a practical surrogate tissue during clinical cardiac NMR investigations.

Severe Ketoacidosis (pH ≤ 6.9) in Type 2 Diabetes: More Frequent and Less Ominous Than Previously Thought

Diabetic ketoacidosis is a life-threatening acute metabolic complication of uncontrolled diabetes. Severe cases of DKA (pH ≤ 7.00, bicarbonate level ≤ 10.0, anion gap > 12, positive ketones, and altered mental status) are commonly encountered in patients with type 1 diabetes and are thought to carry an ominous prognosis. There is not enough information on the clinical course of severely acidotic type 2 diabetes (pH ≤ 6.9) patients with DKA, possibly because this condition is rarely seen in developed countries. In this series, we present 18 patients with type 2 diabetes, DKA, and a pH ≤ 6.9 that presented to a tertiary university hospital over the past 11 years. The objective was to describe their clinical characteristics, the triggering cause, and emphasis on treatment, evolution, and outcomes. The majority of the patients were female (61%). Mean age was 40.66 years (23–59). The patients had been first diagnosed with type 2 diabetes on average 5.27 ± 3.12 years before admission. Glutamic acid decarboxylase (GAD65) antibodies were negative in all patients. The origin of DKA could be attributed to two main causes: treatment omission in 8 (44.4%) patients and infections in 7 (38.8%) patients. The most common symptoms described were general malaise, dyspnea, altered mental status, and abdominal pain. Mean serum glucose on admission was 613.8 ± 114.5 mg/dL. Mean venous pH was 6.84 ± 0.03 with an anion gap of 30.3 ± 2.9 and a venous HCO₃ level of 3.62 ± 1.35 mmol/L. All patients had acute renal failure on admission, with a mean serum creatinine of 1.57 ± 0.35 mg/dL compared to 0.55 ± 0.21 mg/dL at discharge. All patients received regular insulin infusion, aggressive fluid repletion, and 12 patients (66%) received bicarbonate infusion. Mean total insulin infusion dose was 181.7 ± 90.4 U (on average 0.14 ± 0.05 U/Kg/h). Mean time on infusion was 24.4 ± 12.6 hours. We recorded no mortality in this case series. Mean in-hospital stay was 5.0 ± 4.1 days. In conclusion, very severe DKA in type 2 diabetes is not uncommon in our population, shares many features with non-very-severe cases of DKA (bicarbonate therapy did not make a difference in mortality), and can be managed following standard published or institutional guidelines.

Treatment of lactic acidosis: appropriate confusion

BACKGROUND

Lactic acidosis (LA) is common in hospitalized patients and is associated with poor clinical outcomes. There have been major recent advances in our understanding of lactate generation and physiology. However, treatment of LA is an area of controversy and uncertainty, and the use of agents to raise pH is not clearly beneficial.

AIM AND METHODS

We reviewed animal and human studies on the pathogenesis, impact, and treatment of LA, published in the English language and available through the PubMed/MEDLINE database. Our aim was to clarify the physiology of the generation of LA, its impact on outcomes, and the different treatment modalities available. We also examined relevant data regarding LA induced by medications commonly prescribed by hospitalists: biguanides, nucleoside analog reverse-transcriptase inhibitors (NRTIs), linezolid, and lorazepam.

RESULTS/CONCLUSIONS

Lactic acid is a marker of tissue ischemia but it also may accumulate without tissue hypoperfusion. In the latter circumstance, lactic acid accumulation may be an adaptive mechanism-a novel possibility quite in contrast to the traditional view of lactic acid as only a marker of tissue ischemia. Studies on the treatment of LA with sodium bicarbonate or other buffers fail to show consistent clinical benefit. Severe acidemia in the setting of LA is a particularly poorly studied area. In the settings of medication-induced LA, optimal treatment, apart from prompt cessation of the offending agent, is still unclear.

Comparison of sodium bicarbonate and carbicarb for the treatment of metabolic acidosis in newborn calves

Carbicarb (an equimolar mixture of sodium bicarbonate and sodium carbonate) was compared with sodium bicarbonate alone for the treatment of acidosis in newborn calves: 25 of 49 calves with a blood pH at birth of less than 7-2 and a base deficit of less than -3 mmol/litre were treated intravenously with sodium bicarbonate and 24 were treated with carbicarb. The doses were calculated on the basis of the base deficit in a blood sample taken 10 minutes after birth, and further blood samples were taken immediately after the treatment and 30 and 60 minutes after the treatment for the determination of acid-base status, blood gases and haematological and biochemical variables. Both treatments resulted in a significant increase in blood pH, but there was no difference between them. The mean (sd) blood pH before treatment was 7.09 (0.02) and after treatment it was 7.28 (0.01). There was no increase in the partial pressure of carbon dioxide after treatment with either sodium bicarbonate or carbicarb. Both treatments were associated with an increase in sodium concentration and decreases in the total erythrocyte count, haematocrit and haemoglobin concentration.

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.

Treatment of metabolic acidosis

Metabolic acidosis is characterized by a decrease of the blood pH associated with a decrease in the bicarbonate concentration. This may be secondary to a decrease in the strong ion difference or to an increase in the weak acids concentration, mainly the inorganic phosphorus. From a conceptual point of view, two types of nontoxic metabolic acidosis must be differentiated: the mineral metabolic acidosis that reveals the presence of an excess of nonmetabolizable anions, and the organic metabolic acidosis that reveals an excess of metabolizable anions. Significance and consequences of these two types of acidosis are radically different. Mineral acidosis is not caused by a failure in the energy metabolic pathways, and its treatment is mainly symptomatic by correcting the blood pH (alkali therapy) or accelerating the elimination of excessive mineral anions (renal replacement therapy). On the other hand, organic acidosis gives evidence that a severe underlying metabolic distress is in process. No reliable argument exists to prove that this acidosis is harmful under these conditions in humans. Experimental data even show that hypoxic cells are able to survive only if the medium is kept acidic. The management of an acute organic metabolic acidosis is therefore primarily based on the cause of the acidosis, and no scientific argument exists to justify the correction of the acid-base imbalance in this context.

Use of base in the treatment of severe acidemic states

Severe acidemia (blood pH < 7.1 to 7.2) suppresses myocardial contractility, predisposes to cardiac arrhythmias, causes venoconstriction, and can decrease total peripheral vascular resistance and blood pressure, reduce hepatic blood flow, and impair oxygen delivery. These alterations in organ function can contribute to increased morbidity and mortality. Although it seemed logical to administer sodium bicarbonate to attenuate acidemia and therefore lessen the impact on cardiac function, the routine use of bicarbonate in the treatment of the most common causes of severe acidemia, diabetic ketoacidosis, lactic acidosis, and cardiac arrest, has been an issue of great controversy. Studies of animals and patients with these disorders have reported conflicting data on the benefits of bicarbonate, showing both beneficial and detrimental effects. Alternative alkalinizing agents, tris-hydroxymethyl aminomethane and Carbicarb, have shown some promise in studies of animals and humans, and reevaluation of these buffers in the treatment of severe acidemic states seems warranted. The potential value of base therapy in the treatment of severe acidemia remains an important issue, and further studies are required to determine which patients should be administered base therapy and what base should be used.

Sodium bicarbonate for the treatment of lactic acidosis

Lactic acidosis often challenges the intensivist and is associated with a strikingly high mortality. Treatment involves discerning and correcting its underlying cause, ensuring adequate oxygen delivery to tissues, reducing oxygen demand through sedation and mechanical ventilation, and (most controversially) attempting to alkalinize the blood with IV sodium bicarbonate. Here we review the literature to answer the following questions: Is a low pH bad? Can sodium bicarbonate raise the pH in vivo? Does increasing the blood pH with sodium bicarbonate have any salutary effects? Does sodium bicarbonate have negative side effects? We find that the oft-cited rationale for bicarbonate use, that it might ameliorate the hemodynamic depression of metabolic acidemia, has been disproved convincingly. Further, given the lack of evidence supporting its use, we cannot condone bicarbonate administration for patients with lactic acidosis, regardless of the degree of acidemia.

Does bicarbonate therapy improve the management of severe diabetic ketoacidosis?

OBJECTIVE

The use of bicarbonates in the treatment of severe diabetic ketoacidosis remains controversial, especially regarding the benefit/risk ratio. The aim of this study was to assess the efficacy of bicarbonate therapy during severe diabetic ketoacidosis (pH <7.10).

DESIGN

Retrospective study.

SETTING

The emergency unit of a teaching hospital.

PATIENTS

The records of 39 patients consecutively admitted for severe diabetic ketoacidosis were analyzed (pH <7.10). The patients were divided into two groups: group 1 (n = 24; patients with bicarbonate treatment) and group 2 (n = 15; patients without bicarbonate treatment).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We compared two groups of patients presenting with severe diabetic ketoacidosis (pH values between 6.83 and 7.08) treated with or without bicarbonate. A group of 24 patients received 120+/-40 mmol sodium bicarbonate. The two groups were similar at admission with regard to clinical and biological parameters. No difference could be demonstrated between the two groups concerning the clinical parameters or the normalization time of biochemical parameters. If the number of patients with hypokalemia was comparable between the two groups, the potassium supply was significantly more important in group 1 compared with group 2 (366+/-74 mmol/L vs. 188+/-109 mmol/L, respectively; p < .001).

CONCLUSIONS

Data from the literature and this study are not in favor of the use of bicarbonate in the treatment of diabetic ketoacidosis with pH values between 6.90 and 7.10.

Severe diabetic ketoacidosis: the need for large doses of insulin

A 21-year-old female with Type 1 diabetes mellitus (DM) presented in ketoacidosis. She received intravenous normal saline and insulin at 6 U/h and 1.26% sodium bicarbonate solution. After the blood glucose had fallen to 9.5 mmol/l, the saline infusion was changed to 5% glucose solution and the insulin infusion rate to 2 to 3 U/h. The next day the patient became more drowsy (Glasgow coma scale 13/15, later falling to 4/15). Computed tomography (CT) scan suggested cerebral oedema and the patient was treated with dexamethasone and mannitol. She remained critically ill for 48 h, eventually making a full recovery. Insulin was given at rates of 8 to 14 U/h, with 10% or 20% glucose infusion to maintain the blood glucose above 5 mmol/l; despite this it was not until the fifth day that her serum bicarbonate became normal. Textbooks usually advise starting insulin at 6 U/h and reducing the infusion rate to 1-4 U/h when the blood glucose falls below a certain level. In this case, even with high rates of insulin infusion, it took 5 days before the patient's serum bicarbonate returned to normal. Thus, in severe diabetic ketoacidosis (DKA), protocols should advise that the insulin infusion be continued at high dose (4 to 6 U/h or more), with appropriate glucose infusion to prevent hypoglycaemia, until the serum bicarbonate is normal or nearly so.

An evidence-based evaluation of the use of sodium bicarbonate during cardiopulmonary resuscitation

The use of bicarbonate is rooted in three decades of clinical experience and observational studies. For many years, bicarbonate passed the tried and true test for clinical therapies; however, administration of sodium bicarbonate during cardiac arrest and hypoxic acidosis has become increasingly controversial. The controversy provides an excellent opportunity to evaluate the impact an evidence-based approach might have on a common clinical practice. Is bicarbonate efficacious in the treatment of the severe acidosis that accompanies cardiac arrest during cardiopulmonary resuscitation (CPR)? Are the deleterious effects of bicarbonate clinically relevant? What is the evidence upon which a rational decision may be based? This review evaluates and ranks the evidence supporting the use of sodium bicarbonate in the therapy of acidosis associated with cardiac arrest during CPR.

Alkaline buffers for correction of metabolic acidosis during cardiopulmonary resuscitation with focus on Tribonat--a review

A combined hypercarbic and metabolic acidosis develops during the low flow state of cardiac arrest treated with cardiopulmonary resuscitation. Several negative consequences of the acidosis have been demonstrated, two of the most important being reduced contractility of the ischaemic but still beating myocardium and impaired resuscitability of the arrested heart. Even though interventions to re-establish a spontaneous circulation should be the number one priority during cardiopulmonary resuscitation, attempts to treat the acidosis are often carried out in order to avoid the reported negative inotropic effect. Different alkaline buffers have been used, but it has been demonstrated over the years that such treatment may aggravate the situation due to a variety of deleterious side-effects of the buffers. A mixture of THAM, acetate, sodium bicarbonate and phosphate registered as Tribonat has been suggested as a suitable alternative to conventional buffer substances. The problems preceding the designation of Tribonat as well as studies evaluating its effects are reviewed in this article. Tribonat seems to offer a more well-balanced buffering without any major disadvantages compared with previously used alkaline buffers, even though improved survival has not been reported.

Failure of adjunctive bicarbonate to improve outcome in severe pediatric diabetic ketoacidosis

STUDY OBJECTIVE

Although adjunctive intravenous bicarbonate therapy is commonly recommended for children with severe diabetic ketoacidosis (DKA), no studies assessing clinical outcome with this therapy have ever been performed. Our objective was to determine whether bicarbonate therapy influenced outcome for pediatric DKA.

METHODS

The study was a retrospective consecutive case series of 147 admissions for severe DKA (initial pH < or = 7.15 and glucose concentration > or = 300 mg/dL [16.7 mmol/L]) in 106 children during a 16-year period at a tertiary university medical center. Descriptive statistics were applied to the 147 admissions. The first patient admitted with DKA was then selected for each of the 106 children, and clinical and laboratory data were compared between subjects who did and did not receive bicarbonate. Multivariate and matched pair analyses were performed to control potentially confounding variables.

RESULTS

Fifty-seven of the 147 patients admitted with DKA (39%) were successfully treated without bicarbonate, including 9 with a pH of 7.00 or less and one with a pH of 6.73. The frequency of complications was comparable between bicarbonate and nonbicarbonate groups (4% versus 2%, P = 1.00). The mean duration of hospitalization for children receiving bicarbonate was 23% (16 hours) longer than children who did not receive bicarbonate in the multivariate analysis (P = .07) and 37% (22 hours) longer in the matched pair analysis (P = .01). The mean rate of metabolic recovery by three distinct measures was similar between groups, and the sample had 80% power to detect differences of 14% to 29% in these measures.

CONCLUSION

We found no evidence that adjunctive bicarbonate improved clinical outcome in children with severe DKA. The rate of metabolic recovery and complications were similar in patients treated with and without bicarbonate, and prolonged hospitalizations were noted in the bicarbonate group. We conclude that adjunctive bicarbonate is unnecessary and potentially disadvantageous in severe pediatric DKA.