Standard Steps for Preoperative Care

Last week we began a discussion on the preoperative phase of surgery. With athletes like Lebron James playing while injured, with people living longer, and with the growing prevalence of diabetes, surgery is a part of many people’s future. These blogs will help prepare you for what to expect.

After the history and physical exam here at Cast a Foot Podiatry, I will usually order some lab tests like a CBC or BMP. We left off with the basal metabolic profile, or BMP, consisting of sodium, potassium, chloride, carbon dioxide, nitrogen, creatinine, and glucose. Now I will break these down so you understand why it is important to evaluate the levels of these chemicals prior to surgery.

High sodium levels usually means the patient is dehydrated. To confirm, the potassium and nitrogen level (or BUN) can be compared. If these are also elevated, then dehydration is the reason. If they are not, then your high sodium means something could be wrong with your heart or kidneys. You may be required to undergo further cardiac evaluation before having surgery.

Potassium must always be tightly regulated prior to, during, and after surgery. High or low potassium can cause fatal cardiac arrhythmias (unusual heart rhythm). Chloride and carbon dioxide do not prove to be as valuable in assessing for preoperative danger. Fluctuations may be present as the result of vomiting or diarrhea. However, carbon dioxide is how your physician evaluates if your blood is acidic or not.

The level of nitrogen in your urine (BUN) will increase in a dehydrated state like previously discussed. However, it can also implicate kidney failure while a decrease reveals liver failure. The creatinine level helps decide which is which. A normal creatinine means dehydration while an elevated creatinine points to kidney failure.

Lastly, glucose (blood sugar) is important. Most surgeons will not operate on a patient with a glucose over 400 due to poor healing outcomes associated with high blood sugar. Diabetics really need to monitor their glucose levels prior to surgery.


Nicole M. Castillo, DPM 

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