Mixed Deck — All CABT Topics Flashcards

A nurse reports that an electric hospital bed moves very slowly when raising the head section. The biomedical technician checks voltage at the motor and finds it within spec. What should be investigated next?

Answer: Mechanical binding or worn drive mechanism in the bed frame

If electrical supply to the motor is correct, slow movement points to a mechanical issue such as friction, binding, or a worn actuator/gearbox.

What is the anatomical term for the anterior surface of the hand?

Answer: Palmar

The palmar surface refers to the front (anterior) surface of the hand, also called the palm.

A capacitor is connected in series with a resistor to an AC source. As frequency increases, what happens to the capacitive reactance (Xc)?

Answer: Xc decreases

Capacitive reactance Xc = 1/(2πfC), so as frequency increases, Xc decreases.

What is the recommended action when an automated analyzer's QC result exceeds the 3-SD (3 standard deviation) Westgard rule?

Answer: Reject the run, investigate the cause, and do not report patient results until resolved

A 3-SD violation (1₃s rule) indicates random error and requires run rejection, root cause investigation, and re-running QC before releasing patient results.

In a physiologic monitoring system, what is a 'zeroing' procedure used for?

Answer: Establishing the atmospheric pressure as the baseline reference for invasive pressure measurements

Zeroing an invasive pressure transducer exposes it to atmospheric pressure and sets that as the zero reference point, ensuring all subsequent pressure measurements are accurate relative to atmosphere.

During an electrical safety inspection, a technician tests a portable patient monitor. Under NFPA 99 guidelines for equipment used in the patient care vicinity, the chassis leakage current must NOT exceed:

Answer: 300 microamperes

NFPA 99 sets specific limits for leakage current to ensure patient safety. For portable cord-connected appliances used within the "Patient Care Vicinity," the chassis leakage current must not exceed 300 microamperes (µA). This limit helps prevent microshock and macroshock hazards.

Which error in a clinical laboratory water purification system would most directly affect enzyme assays performed that day?

Answer: Elevated conductivity indicating ion contamination

Elevated conductivity signals the presence of ionic contaminants that can inhibit enzyme activity and alter assay results significantly.

When calibrating a pressure transducer to atmospheric pressure, the biomedical technician should confirm the displayed pressure reads:

Answer: 0 mmHg

After zeroing to atmospheric pressure, the monitor should display 0 mmHg, as gauge pressure is measured relative to ambient atmospheric pressure.

What phenomenon occurs when an AC signal causes a transistor to conduct during only part of the input cycle in Class B amplification?

Answer: Crossover distortion

Crossover distortion occurs at the zero-crossing point in Class B push-pull amplifiers due to the transistor's 0.6V threshold voltage.

What is the primary function of the nephron in the kidney?

Answer: Blood filtration and urine formation

The nephron is the functional unit of the kidney, filtering blood and forming urine through filtration, reabsorption, and secretion.

A near-infrared spectroscopy (NIRS) oximeter placed on the forehead primarily monitors:

Answer: Regional cerebral oxygen saturation (rSO2)

NIRS cerebral oximeters use near-infrared light to measure the regional oxygen saturation of the underlying brain tissue in a non-pulsatile manner.

A patient monitor's SpO2 waveform (plethysmograph) is present but the numeric value reads dashes. This most likely indicates:

Answer: Signal detected but perfusion index is too low for reliable numeric calculation

When a waveform is visible but no numeric SpO2 is displayed, the signal quality or perfusion index is insufficient for the algorithm to calculate a reliable value.

What is the time constant (τ) of an RC circuit with R = 10 kΩ and C = 100 µF?

Answer: 1 second

τ = RC = 10,000 Ω × 0.0001 F = 1 second.

A technician sets up an infusion pump for a pediatric patient. The pump alarms 'occlusion' immediately after starting. Which is the FIRST troubleshooting step?

Answer: Check tubing for kinks, closed clamps, or positional blockages

Physical obstructions (kinks, clamps, needle position) are the most common cause of occlusion alarms and must be ruled out before any other intervention.

Which approach is recommended for troubleshooting imaging systems issues?

Answer: Use systematic isolation and testing methods

Systematic isolation and testing methodically narrows down the root cause, making troubleshooting efficient and accurate.

Which FDA device classification requires the most rigorous pre-market approval (PMA) process, typically applied to life-sustaining or life-supporting devices?

Answer: Class III

FDA Class III devices (e.g., implantable pacemakers, ventricular assist devices) pose the greatest risk and require PMA with clinical evidence of safety and effectiveness.

Which international standard specifically governs the safety requirements for medical electrical equipment?

Answer: IEC 60601-1

IEC 60601-1 is the primary international standard establishing general safety and essential performance requirements for medical electrical equipment.

What is the Nyquist theorem's requirement for sampling an analog signal to avoid aliasing?

Answer: Sample at least twice the highest frequency in the signal

The Nyquist theorem states that the sampling rate must be at least twice the highest frequency component of the signal to accurately reconstruct it without aliasing.

Which combining form means 'bone'?

Answer: Oste/o

'Oste/o' is the combining form for bone, used in words like osteoporosis and osteoblast.

Which lubricant is generally recommended for O-rings in medical gas equipment?

Answer: Silicone-based lubricant

Silicone-based lubricants are oxygen-compatible and are recommended for O-rings in medical gas systems; petroleum-based products are fire hazards with oxygen.