Case review
Patient Li was admitted to the emergency room at 11:15 a.m. with “sudden onset of limb weakness for 5+ hours, unable to walk”.
At 12:12, the laboratory results showed a blood potassium level of 2.06 mmol/L, which was diagnosed as “hypokalemia”. The patient was immediately given 10% potassium chloride 15 mL in 5% glucose solution 500 mL and oral potassium chloride extended-release tablets for symptomatic treatment.
At 12:55, the patient suddenly became unconscious, breathing was shallow and irregular, and the cardiac monitor showed no blood pressure monitoring and zero heart rate. Hospital resuscitation was unsuccessful and clinical death was declared at 15:50.
The patient’s Family believed that the hospital had added potassium chloride to glucose in the course of treatment, which might aggravate the hypokalemia, and filed a lawsuit for compensation on the grounds of medical negligence.
Although the above case is an isolated one, it raises the question of whether potassium chloride should be added to sugar or salt for potassium supplementation.
01
Different opinions from different references
Internal Medicine, Ninth Edition: Adding potassium chloride to saline in hypokalemia or to glucose solution if the blood potassium is already normal can prevent hyperkalemia and correct potassium deficiency.
Emergency and Disaster Medicine: Hypokalemia can be prevented by adding 1.0 to 1.5 g of potassium chloride to 500 mL of physiological saline or 5% glucose solution.
Instructions for potassium chloride injection: General use: 10-15 mL of 10% potassium chloride injection is added to 500 mL of 5% glucose injection as a drip.
Harrison’s Internal Medicine, 19th edition: Potassium chloride must be administered in saline rather than sugar water because glucose can induce insulin secretion and lead to acute exacerbation of hypokalemia.
As you can see, the various references are not unanimous on this issue, so what exactly should be done clinically?
02
Clinical preference for “salt first, then sugar
The statement that “glucose can induce insulin secretion and lead to hypokalemia” is rarely mentioned anymore, because a high enough sugar concentration and a high dose of insulin are required to promote a rapid intracellular transfer of potassium in a short period of Time.
The transfer of serum potassium into the cells is weak with 5% glucose without insulin. Therefore, there is nothing wrong with using sugar as a solvent if it is used as a regular potassium supplement.
In addition, using sugar as a solvent also allows the supplementation of extracellular potassium along with intracellular potassium, which improves the effect of potassium supplementation and avoids localized excess of serum potassium concentration.
However, in order to avoid the above mentioned problem of induced insulin secretion, it is generally recommended to follow the idea mentioned in the 9th edition of Internal Medicine when supplementing intravenous potassium, i.e. to start with salt solubilization and then switch to sugar when the blood potassium is normalized.
03
Correct potassium supplementation: manner and speed are key
In the end, correcting hypokalemia is not as simple as “adding more salt when the Soup is bland”. Replenishing too much potassium into the blood vessels in a short period of time can cause a local or transient increase in serum potassium concentration.
Because the decrease in intracellular potassium concentration is greater than the decrease in extracellular potassium concentration, rapid potassium supplementation can easily cause transient hyperkalemia, which can lead to fatal arrhythmias, especially in patients with acute hyperkalemia. Therefore, the most important thing in potassium supplementation is not the solvent, but the manner and speed of supplementation.
So, how to replenish potassium correctly? This question is actually a cliché, so today we will organize it in a simple and brutal way.
- Mild hypokalemia: oral potassium supplementation, 10% potassium chloride preferred, 10% potassium citrate, potassium chloride controlled release tablets second choice, nasal feeding if necessary.
It should be noted that potassium salts have an irritating effect on the mucous membrane of the gastrointestinal tract, so attention should be paid to whether the patient has a gastrointestinal reaction.
- Severe hypokalemia: 15 mL of 10% potassium chloride injection + GS/NS 500 mL intravenously. Use NS first, then GS if potassium is almost normal, which can help prevent hyperkalemia.
The concentration and rate of potassium supplementation should not exceed 40 mmol/L (<0.3% KCl) and 13.4 mmol/h (<1 g/h KCl).
- In case of severe cardiac arrhythmia or respiratory paralysis due to potassium deficiency, the amount of potassium supplementation can be increased and the speed can be accelerated. 5%-10% glucose solution with 10% potassium chloride diluted to 67-134 mmol/L should be given intravenously at a rate of 13.4-20 mmol/h, and should not exceed 20 mmol/h.
- For severe Life-threatening hypokalemia, unconventional forms of potassium supplementation, such as central venous or infusion pumps, may be considered, but this requires a high level of experience and skill.
Case follow-up
Hypokalemia is defined as serum potassium < 3.5 mmol/L. At 12:12, patient Li’s serum test results showed 2.06 mmol/L of potassium, meaning that the patient was severely hypokalemic, and intravenous potassium was administered immediately.
The patient developed acute unconsciousness at 12:55 a.m. Considering the actual execution time of the medical prescription and the onset of medication, it is evident that the actual time of potassium supplementation for Li was relatively short, and within such a short period of time, even if the maximum rate and amount of intravenous potassium supplementation were administered, it would still not change the patient’s physiological state of severe potassium deficiency.
However, considering the fact that the hospital is a Level IIA hospital and that this operation is not a routine medical practice, we can only assume that the hospital doctor was conservative and risk-averse.
As for the way of dispensing the potassium, the hospital did not violate the medical practice and was not at fault because the doctor dispensed the potassium chloride injection in accordance with the instructions.
In addition, there was no record of the patient’s urine volume or the speed of potassium chloride infusion in the patient’s medical records, so the hospital was found to be at fault. However, the monitoring of urine volume and infusion rate was mainly to prevent the patient from developing hyperkalemia, and there was no direct causal relationship with the patient’s death.
In summary, taking into account the patient Li’s condition and the law of disease development, and considering the hospital’s fault in causing Li’s death, the court concluded that the hospital should bear 5% of the fault responsibility, and the remaining 95% should be borne by Li and his family.
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