Potassium deficiency occurring during the treatment of diabetic acidosis

A century of exercise physiology: effects of muscle contraction and exercise on skeletal muscle Na+,K+-ATPase, Na+ and K+ ions, and on plasma K+ concentration-historical developments

This historical review traces key discoveries regarding K+ and Na+ ions in skeletal muscle at rest and with exercise, including contents and concentrations, Na+,K+-ATPase (NKA) and exercise effects on plasma [K+] in humans. Following initial measures in 1896 of muscle contents in various species, including humans, electrical stimulation of animal muscle showed K+ loss and gains in Na+, Cl- and H20, then subsequently bidirectional muscle K+ and Na+ fluxes. After NKA discovery in 1957, methods were developed to quantify muscle NKA activity via rates of ATP hydrolysis, Na+/K+ radioisotope fluxes, [3H]-ouabain binding and phosphatase activity. Since then, it became clear that NKA plays a central role in Na+/K+ homeostasis and that NKA content and activity are regulated by muscle contractions and numerous hormones. During intense exercise in humans, muscle intracellular [K+] falls by 21 mM (range - 13 to - 39 mM), interstitial [K+] increases to 12-13 mM, and plasma [K+] rises to 6-8 mM, whilst post-exercise plasma [K+] falls rapidly, reflecting increased muscle NKA activity. Contractions were shown to increase NKA activity in proportion to activation frequency in animal intact muscle preparations. In human muscle, [3H]-ouabain-binding content fully quantifies NKA content, whilst the method mainly detects α2 isoforms in rats. Acute or chronic exercise affects human muscle K+, NKA content, activity, isoforms and phospholemman (FXYD1). Numerous hormones, pharmacological and dietary interventions, altered acid-base or redox states, exercise training and physical inactivity modulate plasma [K+] during exercise. Finally, historical research approaches largely excluded female participants and typically used very small sample sizes.

Mapping the role of pH-adjusted potassium in diabetic ketoacidosis: Hypokalemia and the patient outcomes

BACKGROUND

Incidence of hypokalemia during the management of diabetic ketoacidosis (DKA) is high despite detailed potassium replacement guidelines in its treatment.

AIM

We aimed to find the role of pH-adjusted potassium (pH_K ) in the development of hypokalemia, and their mutual impact on patient outcomes during DKA management.

METHODOLOGY

Adult DKA patient's admission data of preceding 3 years (2015-2017) were retrospectively clerked. Outcomes of interest were time to develop hypokalemia and to terminate emergency department (ED) care (hours), severity of hypokalemia and hospitalisation length (days). Linear regression was used to determine significant associations/predictors.

RESULTS

The study was concluded on 85 patients. Hypokalemia was observed in nearly 3/4^th of all admissions and occurred by the time of ED care termination. Each 1 mmol/L increase in pH_K significantly (a) reduced the degree of hypokalemia by 0.07 mmol/L, (b) delayed time to develop hypokalemia by 4.58 hours, (c) and reduced the ED care time by 1.28 hours. Arterial pH was the other factor significantly delaying time to develop hypokalemia (36.25 hours) and facilitating early discharge from ED (13.86 hours). Moreover, each 1 mmol/L reduction in the degree of hypokalemia increased hospitalisation length by 1.86 days. Though significant, acute kidney injury negligibly increased hospitalisation length by 0.01 days.

CONCLUSION

pH-adjusted potassium shall be used as a marker for hypokalemia and to initiate potassium replacement instead of measured serum potassium in DKA. Utilising pH_K will help to avoid hypokalemia, reduce its severity and shorten ED care which will subsequently reduce hospitalisation length. We expect pH_K to improve pharmacoeconomics in the future.

Correlation of acidosis-adjusted potassium level and cardiovascular outcomes in diabetic ketoacidosis: a systematic review

BACKGROUND

During the progress and resolution of a diabetic ketoacidosis (DKA) episode, potassium levels are significantly affected by the extent of acidosis. However, none of the current guidelines take into account acidosis during resuscitation of potassium level in DKA management, which may increase the risk of cardiovascular adverse events.

OBJECTIVE

To assess literature regarding the adjustment of potassium level using pH to calculate pH-adjusted corrected potassium level, and to observe the relationship of cardiovascular outcomes with reported potassium level and pH-adjusted corrected potassium in DKA.

METHODOLOGY

Seven databases were searched from inception to January 2018 for studies which had reported people with diabetes developing diabetic ketoacidosis, in relation to prevalence or incidence, fluid resuscitation or potassium supplementation treatment, treatment or cardiovascular outcomes, and experimentation with DKA management or insulin. Quality of studies was evaluated using Cochrane Risk of Bias and Newcastle Ottawa Scale.

RESULTS

Forty-seven studies were included in qualitative synthesis out of a total of 10,292 retrieved studies. Forty-one studies discussed the potassium level and blood pH at the time of admission, ten studies discussed cardiovascular outcomes, and only four studies concurrently discussed potassium level, pH, and cardiovascular outcomes. Only two studies were graded as good on the Newcastle Ottawa Scale. The reported potassium level was well within normal range (5.8 mmol/L), whereas pH rendered patients to be moderately acidotic (7.13). Surprisingly, none of the included studies mentioned pH-adjusted corrected potassium level and, hence, this was calculated later. Although mean corrected potassium was within the normal range (3.56 mmol/L), 13 studies had corrected potassium below 3.5 mmol/L and five had it below 3.0 mmol/L. Nevertheless, with the exception of one study, none discussed cardiovascular outcomes in the context of potassium or pH-adjusted potassium level.

CONCLUSION

The evidence surrounding cardiovascular outcomes during DKA episodes in light of a pH-adjusted corrected potassium level is scarce. A prospective observational, or preferably, an experimental study in this regard will ensure we can modify and enhance safety of existing DKA treatment protocols.

Respiratory failure in diabetic ketoacidosis

Respiratory failure complicating the course of diabetic ketoacidosis (DKA) is a source of increased morbidity and mortality. Detection of respiratory failure in DKA requires focused clinical monitoring, careful interpretation of arterial blood gases, and investigation for conditions that can affect adversely the respiration. Conditions that compromise respiratory function caused by DKA can be detected at presentation but are usually more prevalent during treatment. These conditions include deficits of potassium, magnesium and phosphate and hydrostatic or non-hydrostatic pulmonary edema. Conditions not caused by DKA that can worsen respiratory function under the added stress of DKA include infections of the respiratory system, pre-existing respiratory or neuromuscular disease and miscellaneous other conditions. Prompt recognition and management of the conditions that can lead to respiratory failure in DKA may prevent respiratory failure and improve mortality from DKA.

Acute hyperglycemic crisis in the elderly

The geriatric population is at particular risk for developing hyperglycemic crises with the development of diabetes. With increasing age, insulin secretory reserve, insulin sensitivity, and thirst mechanisms decrease. The elderly are particularly vulnerable to hyperglycemia and dehydration, the key components of hyperglycemic emergencies. If recognized early, hyperglycemia can frequently be treated in the outpatient setting even with moderate or large ketonuria, provided patients can take fluids, monitor blood glucose frequently, and follow standard "sick day rules." With increased diabetes surveillance and aggressive early treatment of hyperglycemia and its complications, morbidity and mortality from acute diabetic crises in the geriatric population can be greatly reduced.

Hypokalemia in children with severe falciparum malaria

OBJECTIVES

Acidosis is now recognized as an important component of the severe malaria syndrome and a predictor of fatal outcome. Alterations in plasma potassium concentrations are commonly associated with acidosis. To date, there is little information about the changes in potassium in severe malaria.

DESIGN

Prospective study examining the changes in plasma potassium in the first 24 hrs following admission in children with severe malaria. Urinary fractional excretion of potassium and the transtubular gradient of potassium were examined at admission.

SETTING

High-dependency unit on the coast of Kenya.

PATIENTS

Kenyan children admitted to hospital with clinical features of severe malaria (impaired consciousness or deep breathing) complicated by acidosis (base deficit >8).

INTERVENTIONS

Children received standard therapy for severe malaria; in addition, they received boluses of either 0.9% saline or 4.5% human albumin solution to correct hypovolemia, and intravenous potassium replacement was prescribed to children who developed hypokalemia (plasma potassium <3 mmol/L).

MEASUREMENTS AND MAIN RESULTS

Thirty-eight Kenyan children were recruited with severe malaria and acidosis. At admission, serum potassium was normal (3-5.5 mmol/L) in 31 (81.6%) and low (<3 mmol/L) in four (11%) children, and three (6.3%) children had hyperkalemia (>5.5 mmol/L). Plasma potassium decreased rapidly within 4-8 hrs of admission: 15 (40%) patients were hypokalemic (<3 mmol/L); of these, five (13%) had plasma potassium of <2.5 mmol/L. Fractional excretion of potassium and the transtubular gradient of potassium were above normal range, indicating renal potassium loss.

CONCLUSIONS

Hypokalemia is a common complication of severe malaria; however, it is often not apparent on admission. On correction of acidosis, plasma potassium decreases precipitously, and thus careful, serial monitoring of serum potassium is suggested in patients with severe malaria complicated by acidosis.

A paper which changed clinical practice (slowly). Jacob Holler on potassium deficiency in diabetic acidosis (1946)

It is often said that the introduction of insulin into clinical medicine made a 'dramatic' difference to the mortality resulting from diabetic coma. This is true in the sense that before 1922 it was almost uniformly fatal, but until the 1950s the mortality in many large hospitals was as high as 30-50%. Often autopsy did not establish a cause of death. Many may have been a result of hypokalaemia, a complication which was not recognized until 1946; in that year in the Journal of the American Medical Association, Jacob Holler described a patient who developed respiratory paralysis 12h into treatment that, after several hours in an iron lung, was cured by potassium infusion. In the 5 years after Holler's paper there were many reports of deaths resulting from hypokalaemia, as well as several 'near misses', but clinicians were extremely cautious about early replacement probably, as an editorialist in The Lancet suggested, because 'the frightening effects of intravenous injections of potassium made clinicians reluctant to believe in a lack of potassium as a cause of trouble, except in very rare conditions such as familial periodic paralysis'. It had been known since 1923 that insulin lowered serum potassium, but this was not of great interest because the symptoms of hypokalaemia were not known. Also, potassium was not an electrolyte with which clinicians were familiar. Until the introduction of flame photometry in 1950, it was only measured in research studies as chemical methods took several hours to complete.

Hypokalaemia occurring during insulin-induced hypoglycaemia

Insulin-induced hypoglycaemia was used to test pituitary function in six patients with suspected pituitary deficiency. In each, a fall in serum potassium concentration of from 0-63 to 1-48 mEq/litre (mean fall 1-10 mEq/litre +/- 0-30 SEM) was observed during the two hour period following administration of 1-15 units of insulin per kilogram body weight. In several patients the resulting hypokalaemia was at a level which has been associated with cardiac complications.

Pathogenesis, diagnosis and treatment of diabetic ketoacidosis

The diagnosis of diabetic ketoacidosis must be suspected and the initiation of treatment should be prompt to provide a satisfactory outcome in the treatment of diabetic ketoacidosis. Corrections of fluid and electrolyte deficiencies should be made slowly; rapid "push"injections or large infusions of sodium bicarbonate should avoided and ample amounts of potassium should be given early. Precautions should be taken so that blood glucose concentrations do not fall rapidly, and so that blood glucose levels of 250-300 mg/100 ml are maintained by the administration of 5-10% glucose solutions. Bicarbonate therapy is indicated only in severe acidosis (pH less than or equal to 7.1). Physicians who are trained in the care of diabetes mellitus should supervise the treatment. In our hospital the same staff physicians and fellows attend all patients with diabetes. In addition the efforts of our house staff and nurses have contributed significantly to the care of these patients.

The relation of cardiovascular phenomena to metabolic changes in a patient with chronic hypokalemia

Cardiovascular phenomena were studied and correlated with metabolic data in an adult male with chronic hypokalemia. The appearance and disappearance of postural hypotension, the changes in heart rate, the S-T segment shifts, and the U-wave amplitudes correlated well with the changing serum potassium level during experimental acute potassium depletion. QRS and T-wave changes could not be correlated with metabolic data. Comparison with the cardiovascular manifestations of experimental potassium depletion in normal subjects suggested that this patient had a chronic potassium depletion of at least 300 mEq.