Want to test your equipment knowledge before the CRNA exam? Below are free sample flashcards from the 80-card equipment section of our 1050-card CRNA (Certified Registered Nurse Anesthetist) deck, which covers Circle System and more.
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A student CRNA accidentally fills a Sevoflurane (VP 157) vaporizer with Isoflurane (VP 238). What is the expected effect on the delivered concentration of anesthetic gas to the patient, and why?
Show answer →The patient will receive a HIGHER concentration than the dial indicates. This follows the HLH rule (High vapor pressure agent in a Low vapor pressure vaporizer). Because Isoflurane is more volatile (higher VP) than Sevoflurane, the carrier gas passing through the vapor chamber will pick up more molecules than the vaporizer's splitting ratio was designed for. Exam Strategy: Memory aid HLH (High in Low = High) and LHL (Low in High = Low). NBCRNA frequently tests the safety implications of misfilling. Note that modern keyed fillers make this difficult, but the physics remains a high-yield topic. If the agents were reversed (Sevo in Iso), the output would be lower than dialed.
A CRNA is using a machine with a Selectatec manifold. What specific safety mechanism prevents the simultaneous administration of multiple volatile anesthetics, and to which pressure system does this belong?
Show answer →This is the Vaporizer Interlock System, located in the Low Pressure System. It mechanically prevents more than one vaporizer from being turned on at a time. It also ensures vaporizers are locked into the manifold to prevent leaks. Note: If the interlock fails and two vaporizers are on, the total anesthetic depth is unpredictable, and cross-contamination of agents can occur.
Which component of the circle system is responsible for ensuring that gas flow is unidirectional and where must these components be located to prevent rebreathing?
Show answer →Unidirectional valves (Inspiratory and Expiratory). For a circle system to prevent rebreathing of CO2, three rules must be met: 1. Unidirectional valves must be located between the patient and the reservoir bag on both limbs, 2. The Fresh Gas Flow (FGF) must NOT enter the circuit between the expiratory valve and the patient, and 3. The APL valve must NOT be located between the patient and the inspiratory valve. Exam Tip: If a valve sticks open (incompetence), the patient will rebreathe exhaled CO2, manifested as an elevated baseline on the capnograph (Alpha angle disruption).
How does the lack of unidirectional valves and CO2 absorbers in Mapleson circuits affect the composition of inspired gas compared to a Circle System?
Show answer →Mapleson circuits are semi-open or semi-closed depending on FGF. Without valves or absorbers, the prevention of rebreathing is entirely dependent on FGF. If FGF is insufficient, rebreathing of CO2 occurs. Advantage: Lower resistance (good for peds). Disadvantage: High FGF requirements lead to waste of anesthetic gases and loss of heat and moisture.
A 45-year-old female with a BMI of 32 presents for an umbilical hernia repair. Which patient factor serves as a relative contraindication to LMA use, necessitating careful consideration of a Second-Generation device or ETT?
Show answer →Increased risk of aspiration (e.g., GERD, obesity, non-fasting status, or delayed gastric emptying). While BMI >30 is a relative contraindication, SGLADs (Supreme/ProSeal) are frequently used in low-risk obese patients in modern practice. NBCRNA focuses on Full Stomach as the primary absolute contraindication for elective LMA use. Distractor: Difficult intubation is an indication for LMA.
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Try 30 free CRNA cards firstThe full CRNA deck contains 1050 flashcards, and 80 of them focus on equipment. This page shows 5 free samples.
Our CRNA deck dedicates 80 of 1050 cards (8%) to equipment — always cross-check the official NBCRNA exam outline for the current blueprint weighting.
Yes — the samples on this page are free, and the CRNA preview page has 30 more free cards. Full access to all 1050 cards is a one-time $7.
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