A nurse is reviewing the ECG tracing strip of a client who is receiving telemetry monitoring.
The nurse should locate the S-T segment at which of the following locations on the electrocardiographic waveform.
The flat line between the QRS complex and the T wave.
The peak of the R wave.
The beginning of the P wave.
The interval between the S wave and the T wave.
The Correct Answer is A
Choice A rationale
The ST segment represents the time from the end of ventricular depolarization to the beginning of ventricular repolarization. It is identified as the flat baseline following the QRS complex and preceding the T wave. This segment is isoelectric, meaning it's at the same level as the PR segment, and any deviation can indicate myocardial ischemia or injury.
Choice B rationale
The peak of the R wave represents the peak of ventricular depolarization. It signifies the moment of maximum electrical activity in the ventricles, as the impulse spreads through the ventricular walls. It is a critical point in the QRS complex, but it is not the location of the ST segment.
Choice C rationale
The beginning of the P wave marks the onset of atrial depolarization. This electrical event represents the contraction of the atria as they pump blood into the ventricles. The P wave is the first deflection in the cardiac cycle and occurs well before the QRS complex and the ST segment.
Choice D rationale
The interval between the S wave and the T wave is not a standard electrocardiographic term. The correct terminology is the ST segment, which is a segment, not an interval, and it specifically follows the S wave and precedes the T wave. An interval would typically include a wave, like the QT interval. *.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice A rationale
A tympanogram is a diagnostic test that measures the movement of the eardrum in response to changes in air pressure in the ear canal. It is used to assess the function of the middle ear and is not a part of the Weber's test. The Weber's test is a gross screening tool for hearing acuity that uses a vibrating tuning fork to compare bone conduction in both ears, not to evaluate middle ear function.
Choice B rationale
The Weber's test is a simple screening tool to detect unilateral hearing loss. The nurse places a vibrating tuning fork on the midline of the child's head, such as the forehead or the top of the head. The sound is transmitted through the skull bones to the inner ears. The child is asked where the sound is heard best—in the left ear, right ear, or equally in both. This assesses bone conduction.
Choice C rationale
The Weber's test evaluates whether the sound is heard equally in both ears or lateralizes to one ear, indicating a potential conductive or sensorineural hearing loss. It does not measure the duration of sound perception. Measuring the amount of time a client can hear the sound after the tuning fork is placed on the mastoid bone is part of the Rinne test, a different component of hearing assessment, which compares bone and air conduction.
Choice D rationale
Holding a vibrating tuning fork 1 to 2 cm from the ear canal is a procedure used for the Rinne test, not the Weber's test. The Rinne test compares air conduction to bone conduction. The vibrating tuning fork is placed first on the mastoid bone (bone conduction) and then near the ear canal (air conduction). This is used to distinguish between conductive and sensorineural hearing loss. *.
Correct Answer is B
Explanation
Choice A rationale
Increasing the rate of formula delivery would worsen hyperosmolar dehydration. A faster rate delivers more solute-rich formula to the gastrointestinal tract in a shorter time, pulling more free water from the body's vascular space into the gut lumen via osmosis. This fluid shift further depletes the body's free water, intensifying the dehydration and increasing serum osmolality.
Choice B rationale
Hyperosmolar dehydration occurs when the body's free water is drawn into the gastrointestinal tract due to a high solute concentration in the enteral formula. By adding free water to the formula, the nurse dilutes the solution, lowering its osmolarity. This action helps to balance the osmotic gradient, reducing the fluid shift and preventing further dehydration.
Choice C rationale
Switching to a lactose-free formula is indicated for clients with lactose intolerance, which causes symptoms like diarrhea and bloating, but it does not directly address hyperosmolar dehydration. Hyperosmolar dehydration is related to the overall solute load and concentration of the formula, not specifically the presence or absence of lactose.
Choice D rationale
Repositioning the NG tube is an action to ensure proper placement and prevent complications like aspiration, but it does not resolve hyperosmolar dehydration. This type of dehydration is a systemic problem related to fluid and electrolyte balance, not a local issue with the tube's position within the gastrointestinal tract. *.
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