1. You observe the following on the bedside capnograph display of a patient receiving ventilatory support. What is your interpretation of this display data?
A. ventilator disconnection
D. increased cardiac output
This capnogram shows a progressive reduction in expired CO2, most commonly indicating hyperventilation. Other problems that this display could indicate include hypothermia/reduced metabolism, or sedation/neuromuscular paralysis.
The correct answer is: hyperventilation
2. On inspection of an ECG rhythm strip from an adult patient, you note the following: rate of 150; regular rhythm; normal P waves, P-R intervals, and QRS complexes. The most likely problem is:
A. atrial utter
B. sinus tachycardia
C. ventricular tachycardia
D. atrial fibrillation
The most likely problem is sinus tachycardia. In this arrhythmia, the sinus node rate ranges from 100-160/min. e rhythm is regular, with normal P waves, P-R intervals, and QRS complexes. Many different factors can cause sinus tachycardia. Treatment aims at correcting the underlying cause. Drugs used to slow the heart rate include digitalis and beta-adrenergic blockers like propranolol.
The correct answer is: sinus tachycardia
3. On inspection of a 12-lead ECG, you note the absence of P waves and a variable R-R interval (> 0.12 sec). Which of the following is the most likely problem?
A. atrial hypertrophy
B. First-degree heart block
C. atrial fibrillation
D. sinus arrhythmia
A variable R-R interval (> 0.12 sec or > 10% variation) indicates either sinus arrhythmia or atrial fibrillation. e absence of P waves rules out sinus arrhythmia, making atrial fibrillation the most likely problem.
The correct answer is: atrial fibrillation
4. What percent decrease in FEV1 needs to occur to conclude that a methacholine challenge is positive for airway hyperreactivity?
The methacholine challenge assesses changes in airway caliber with increasing concentrations of methacholine. Patients with hyperreactive airways will show early changes at low dosages. A 20% decrease in FEV1 is considered a positive result. e methacholine concentration at which a 20% decrease in FEV1 occurs is called the “provocative concentration,” or PC20. The lower the PC20, the worse the airway hyperreactivity.
The correct answer is: 20%
5. A patient is receiving ventilatory support after thoracic surgery. You measure the patient’s maximum inspiratory pressure (MIP/NIF) as -33 cm H2O. Based on this value, the patient has:
A. a need for continued ventilatory support
B. a large leak in their endotracheal tube cu
C. a normal maximum inspiratory pressure
D. adequate muscle strength to consider weaning
The maximum inspiratory pressure (MIP/NIF) is a traditional measure used to assess readiness for weaning. The threshold level that has been used to indicate readiness to wean is a negative value below -25 to -30 cm H2O. e measured MIP (-33 cm H2O) here suggests that this patient may be ready for weaning. Of course, other consideration should be taken into account. If fact, current evidence suggests that the following are better indicators of weaning readiness than traditional bedside measures like MIP: 1) some reversal of the underlying cause of respiratory failure; and 2) adequate oxygenation (P/F > 150-200; PEEP ≤ 8 cm H2O, FIO2 ≤ 0.4-0.5); 3) an arterial pH ≥ 7.25; 4) presence of stable hemodynamics, e.g., no myocardial ischemia or significant hypotension; and 5) presence of spontaneous breathing effort.
The correct answer is: adequate muscle strength to consider weaning
6. During a single-breath capnogram, the sharp downstroke and return to baseline that normally occurs after the end-tidal point indicates:
A. exhalation of mainly deadspace gas
B. inspiration of fresh respiratory gas
C. exhalation of mixed alveolar/deadspace gas
D. exhalation of mainly alveolar gas
During a normal single-breath capnogram, the sharp downstroke and return to baseline that occurs after the end-tidal point indicates inhalation of fresh gas with zero carbon dioxide.
The correct answer is: inspiration of fresh respiratory gas
7. A patient is considered as having sufficient respiratory muscle strength to maintain adequate ventilation and prevent secretion retention when the maximum inspiratory pressure (MIP; NIF) is more negative than:
A. -5 cm H2O
B. -10 cm H2O
C. -15 cm H2O
D. -20 cm H2O
Most clinicians cite -20 to -25 cm H2O as the threshold level for the MIP/NIF, meaning that only patients who can generate values more negative than this (e.g., – 40 cm H2O) are likely able to maintain adequate ventilation and take breaths deep enough to facilitate coughing and secretion clearance. In the past, values more negative than -20 to -25 cm H2O (along with other bedside measures like the VC) also were used to indicate that a patient was ready for weaning.
The correct answer is: -20 cm H2O
8. Over a 3-hour period, the plateau pressure of a patient receiving volume controlled ventilation has remained stable, but her peak pressure has been steadily increasing. Which of the following is the best explanation for this observation?
A. the patient’s airway resistance has increased
B. the patient is developing atelectasis
C. the patient’s compliance has decreased
D. the patient is developing pulmonary edema
With a constant flow, differences between the peak and plateau pressure are directly proportional to the airway resistance. In this case, an increase in the peak – plateau pressure difference signals an INCREASE in airway resistance. All other choices suggest decreased compliance, which would affect the plateau – PEEP pressure difference, not the peak – plateau pressure. Remember “R-C-P”: R = Resistance (peak pressure); C = compliance (plateau pressure); P = PEEP (baseline pressure).
The correct answer is: the patient’s airway resistance has increased
9. On inspection of an adult patient’s 12-lead ECG, you note a regular R-R interval of 0.40 sec, with no other apparent abnormalities. Which of the following is the most likely problem?
A. ventricular tachycardia
B. sinus bradycardia
C. atrial fibrillation
D. sinus tachycardia
In an adult patient, the presence of a regular R-R interval of 0.40 sec (rate = 60/0.40 = 150/ min) indicates a sinus tachycardia. In sinus bradycardia, the R-R interval would be > 1.0 second (rate < 60/min). e ECG of patients with ventricular tachycardia typically reveals abnormally widened QRS complexes, whereas atrial fibrillation is characterized by an irregular rate.
The correct answer is: sinus tachycardia
10. Under ideal conditions, pulse oximeter readings patients usually fall with what percent of those obtained via invasive hemoximetry?
In terms of accuracy, pulse oximetry readings in sick patients usually fall within ±3-5% of those obtained via invasive hemoximetry. In general, the lower the actual SaO2, the less accurate and reliable the SpO2. Most clinicians consider pulse oximeter readings unreliable at saturations below 70%.
The correct answer is: ±3-5%
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