American Board of Surgery Qualifying Exam (ABS QE) Practice Test

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Prepare for the ABS QE with flashcards and multiple-choice questions. Each question provides hints and explanations to enhance understanding. Start your journey to becoming a certified surgeon and tackle your exam with confidence!

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What is the normal level of CO2 that should be maintained before performing the apnea test?

40 mmHg
45 mmHg
55 mmHg
60 mmHg

The correct answer is: 45 mmHg

The normal level of carbon dioxide (CO2) that should be maintained before performing the apnea test is 45 mmHg. This level is important because the apnea test is designed to assess whether an individual has a functional brainstem, which can respond to rising levels of CO2. In this test, CO2 levels are intentionally allowed to rise, and a value of around 45 mmHg indicates the threshold at which the brainstem should show signs of respiratory drive. If the patient does not exhibit any breathing response at this level, it suggests that the brainstem responses are absent, which is a criterion often used in determining brain death. Various clinical guidelines usually support this 45 mmHg target as the upper limit of normal arterial CO2, ensuring that conditions are safe and appropriate for assessing neurological function. Maintaining CO2 at this level balances the need for testing brainstem activity while avoiding excessive hypercapnia, which could lead to other complications. Therefore, 45 mmHg is the targeted level prior to executing this critical examination.