Mrs. Bush, a 70-year-old woman, is admitted to the hospital. Her history states that she has been suffering from diarrhea for three weeks. On admission, she complains of severe fatigue and muscle weakness. A blood chemistry study yields the following information: Na⁺ 142 mEq/L; K⁺ 1.5 mEq/L; Cl ⁻ 92 mEq/L; Pco₂ 32 mm Hg. Which electrolytes are within normal limits? Which are so abnormal that the patient has a medical emergency? Which of the following represents the greatest danger to Mrs. Bush? a. a fall due to her muscular weakness, b. edema, c. cardiac arrhythmia and cardiac arrest.

Video transcript

Hi, everyone. Let's look at our next problem, Mr Cheyenne, who is a healthy individual, developed diarrhea. Seven days ago, he complained about 12 to 14 episodes of watery stools each day. He is reluctant to take medical care and has been using home remedies to treat diarrhea last night, he presented in the A&E department with severe cardiac arrhythmia, which of the following could be a possible explanation for his arrhythmia. A severe dehydration leading to hypotension and cardiac arrest b excessive loss of potassium in the watery stools causing low plasma potassium levels and cardiac arrhythmia c home remedies resulting in the weakening of cardiac muscles or D diarrhea, resulting in septicaemia and cardiac arrest. Well, first of all, we can eliminate the answer. Choice is A and D because both have the term cardiac arrest, we're not talking about cardiac arrest, the stopping of the heart. We're talking about a cardiac arrhythmia, so a disruption to normal heart rhythm. So in the interest of ruling things out right away, we can cross out choices A and D. In addition, choice A uh which is severe dehydration leading to hypertension that can happen, dehydration, the loss of fluid could lead to dangerously low blood pressure. But again, we're talking about arrhythmia, not cardiac arrest. I'm the same with choice. D Septem septicaemia, meaning a blood infection. Again, we're not talking about cardiac arrest nor do we have any indications that he has septicaemia. So let's think again about what arrhythmia is. So it's a disruption to the normal heart rhythm, which is usually a result of disruption to the heart's electrical signals. Since that's what regulates that rhythm of the heartbeat. And what do we need to propagate electrical signals? We need ions crossing membranes to propagate those signals. So when we look at our answer, choices, choice b excessive loss of potassium is the most likely cause because potassium is one of the ions that's important in that electrical activity of the heart. So an excessive loss of potassium that would cause low plasma potassium levels could absolutely disrupt the electrical signals. And let's just take a final look at choice C which is home remedies resulting in the weakening of cardiac muscles. Well, weakening of cardiac muscles, we wouldn't expect to cause arrhythmia. So again, since that's as a result of the electrical signals, not an actual weakening of the contractions of the muscles. So that's why choice C isn't our answer. So again, the likely cause of the arrhythmia that Mr Shayan has developed is choice b excessive loss of potassium in the watery stools causing low plas plasma potassium levels. And cardiac arrhythmia. See you in the next video.