**3.2 Potassium level**

Any type of anesthesia may raise potassium to a critical level suddenly. Therefore, it is particularly important to pay close attention to ECG changes even for minor changes in the QRS complex or the height of the T wave. If recognized, the potassium level must be checked immediately. If elevated, immediate treatment to decrease the potassium should be initiated. Treatment for hyperkalemia starts with immediate administration of calcium (10 ml of 10% calcium chloride). A bolus dose of insulin (5–10 units while checking serum glucose simultaneously) should be followed by a continuous infusion of D10W with 5–10 units of regular insulin per 25–50 g of glucose. After this, sodium bicarbonate (50 to 100 mEq) and furosemide (if the patient still can make urine) should be administered. Other methods to decrease the potassium level includes increasing the respiration rate (if the patient's respiration is controllable under GA). Frequent checks of the potassium level should be performed until it is normalized.

#### **3.3 Heparin**

The surgeon will request heparin prior to clamping the artery. It is important to verify the dose of heparin by asking the surgeon again immediately before giving and flushing the lines to confirm the administration. We should inform the surgeon every hour after the initial and/or additional heparin is administered.

#### **3.4 Oxygenation status**

In cases undertaken with LA or RA where a patient is requiring high doses of sedatives, it can become difficult to maintain the patient of the airway. This can expose the patient to risk of hypoxia. In this situation, an adjunctive airway device can be placed with use of an oral or nasal airway or a conversion to GA with endotracheal tube or LMA should be considered to secure the airway. Since inserting an airway instrument, without muscle reluctance, is sometimes enough to stimulate the patient to move suddenly, the procedure should be paused during the intervention. It should be noted that the risk of bleeding during laryngoscopy and intubation is potentiated if the security of the airway is needed after heparin is administrated. Also, the possibility of potassium increase caused by respiratory acidosis during the patient's spontaneous respiration should be considered.

## **3.5 Choice of sedatives**

A choice for sedatives during monitored anesthesia care is up to the anesthesiologist. However, we should consider the renal function of the patients is significantly impaired and that respiratory depression due to the sedatives may enhance to increase potassium due to respiratory acidosis. In addition to traditional sedatives, such as midazolam and fentanyl, relatively newer sedatives such as propofol, dexmedetomidine and remifentanil have been used to keep the patients calm and comfortable. The metabolism of propofol is not significantly affected by renal dysfunction and it remains a very popular one. However, it may cause respiratory depression if given at higher doses such as 100 micrograms/kg/min. If you need a higher dose, adding midazolam and/or fentanyl may be to reduce the dose. In terms of avoiding respiratory depression, dexmedetomidine is an excellent choice but may make systemic blood pressure lower than expected by decreasing HR. Even if lower BP may not happen during the surgery, it may happen in postoperative period due to a longer half-life of dexmedetomidine. A lower dose of remifentanil (less than 0.5 microgram/kg/min) can sedate the patients without inhibiting spontaneous respiration, but it may cause apnea if it is accidentally flushed. As described, any sedative has advantages and disadvantages of which the selection must be based on each individual patient's demand and background.
