I. Ideal range of postoperative blood potassium in hypokalemia
Rheumatic heart disease: 4.5-5.0mmol/L
Coronary heart disease and congenital heart disease: 4.0-4.5 mmol/L The formula for calculating the amount of potassium deficiency is as follows
Potassium deficiency (mmol/L) = (ideal value mmol/L – measured value mmol/L) * 0.3 * body weight (kg)
Potassium content of potassium solutions of different concentrations (mmol) Potassium content of solutions (ml)
3‰ 6‰ 9‰ 12‰ 15‰ 30‰
10 0.4 0.8 1.2 1.6 2 4
20 0.8 1.6 2.4 3.2 4 8
30 1.2 2.4 3.6 4.8 6 12
40 1.6 3.2 4.8 6.4 8 16
50 2 4 6 8 10 20
100 4 8 12 16 20 40
150 6 12 18 24 30 60
200 8 16 24 32 40 80
Potassium supplementation precautions.
1. Intravenous pushing of potassium chloride is absolutely prohibited.
2. The input of potassium-containing solution should not be too fast and too much per unit time, which may lead to hyperkalemia. Adults should not receive more than 20 mmol of potassium per hour, generally at a rate of 0.2-0.3 mmol/kg/h, with the fastest rate not exceeding 0.5 mmol/kg/h.
3.High concentration (>6‰) potassium-containing liquid should be input from deep vein and take a special pipeline, not from superficial vein, so as not to cause phlebitis.
4.Patients with low urine and renal failure are prone to hyperkalemia, so potassium supplementation should be cautious.
5. When there is a lot of urine and a lot of potassium deficiency, in addition to replenishing the missing potassium, the potassium lost by urination should also be continued. If you have little urine and little potassium deficiency, the concentration of potassium solution should be low, 3‰ or 6‰ solution is available.
6. If high concentration potassium-containing solution is used, the amount should not be too much each time, and the infusion speed should be precisely controlled by an infusion pump to avoid unintentional input of too much potassium chloride. In addition, when measuring CVP, high concentration potassium solution should not be used to avoid excessive potassium input.
7. Generally, half of the amount of potassium deficiency should be supplemented first, and the rate of potassium supplementation should be adjusted after rechecking the blood potassium to avoid oversupply of potassium leading to hyperkalemia.
8, hypokalemia can be accompanied by alkalosis, correcting alkalosis is beneficial to correct hypokalemia.
9. When acidosis is accompanied by hypokalemia, potassium should be supplemented before correcting acidosis, so as not to make the blood potassium even lower after correcting acidosis.
10.Oral potassium supplementation is the safest, and patients who can eat should take oral potassium supplementation. However, because oral potassium chloride and potassium citrate have strong gastrointestinal irritation, some patients react strongly. If the low potassium is serious, intravenous access for potassium supplementation is preferred.
11. For long-term hypokalemia that is difficult to correct due to diuresis, add a potassium-preserving diuretic, Antiseptic 20mg Qd (adult dose). However, attention should be paid to regular serum potassium checks to avoid hyperkalemia.
II. Hyperkalemia
1) Potassium > 4.5 mmol/l Stop potassium supplementation
2） Potassium >5.0mmol/l
(1) Stop potassium supplementation.
(2) 5% sodium bicarbonate 1-2ml/kg, so that potassium enters the cells.
(3) 10% Cacl2 (10-25mg/kg) to antagonize the damage of potassium to the heart.
(4) 50% glucose (1mg/kg) solution with regular insulin 0.1-0.3/kg, dripped over 15-30 minutes to facilitate the transfer of k into the cells.
(5) Furosemide 1-2mg/kg diuretic to promote k excretion
(3) Potassium >7.0mmol/l, acute renal insufficiency, dialysis
III. Hypocalcemia
Large amount of blood transfusion, albumin transfusion and 5% sodium bicarbonate supplementation can combine with Ca to cause low calcium, if the hemodynamics is not stable or need a lot of positive inotropic drugs to maintain the circulation, while the blood calcium is lower than 1.0mmol/l, should actively add calcium treatment 10% calcium gluconate 50mg/kg or 10% calcium chloride 25mg/kg
IV. Metabolic acidosis
5% NaHCO3 (ml) required for correction of metabolic acidosis = -BE*body weight*0.3 Give 1/2-2/3 amount of primary disease correction first, correct hypoxia and maintain smooth hemodynamics.
Note: prevent calcium deficiency convulsions correct acidosis at the same time pay attention to prevent hypokalemia NaHCO3 should be input separately to review blood gas.
V. Respiratory acidosis
Symptoms: hyperventilation, shortness of breath, cyanosis, chest tightness, headache and other clinical symptoms
(1) Adjust the ventilator parameters and increase the ventilation volume.
(2) If Pco2>70mmhg after extubation, carbon dioxide anesthesia and secondary intubation may result.
VI. Respiratory alkalosis
Diagnostic points
(1) Medical history: use of ventilator.
(2) Prognosis: shallow and rapid breathing, numbness or twitching of the extremities.
(3) Increased BE, increased PH.
(4) Decreased partial pressure of carbon dioxide in blood gas.
Prevention and treatment principles: actively treat the original disease to adjust ventilator parameters, reduce ventilation to correct hypocalcemia, and eliminate hand and foot twitching.