Typical lengthy question for step 3, we've 72 - triplehelix

[ArchivalUser]

371.
A 58-year-old female was intubated and placed on mechanical ventilation in the setting of pneumococcal
pneumonia and bacteremia. She is treated with moxifloxacin based on sensitivities and improves over the
course of 5 days. She required vasopressors for the initial 3 days but now has a stable blood pressure of
130/72. The patient's sedative medications have been halved. The patient remains mildly sedated but is
following commands and has a strong cough. Vital signs reveal a heart rate of 90 beats/min, a blood
pressure of 130/72, a respiratory rate of 16, and an SaO2 of 96%. The ventilator settings currently are
SIMV rate 12, FIO2 0.4, PEEP 5 cmH2O, and pressure support 5 cmH2O. The respiratory therapist
initiates a spontaneous breathing trial on continuous positive airway pressure (CPAP) 5 cmH2O for 1 min.
During that time the patient has a spontaneous respiratory rate of 20 breaths/min with a tidal volume of
450 mL. The patient has a negative inspiratory pressure of “40 cmH2O. At this time the patient
continues on CPAP 5 cmH2O with an FIO2 of 0.4. After 30 min of spontaneous breathing, the patient's
heart rate has increased to 136, but blood pressure remains stable. The patient's respiratory rate has increased to 24 with a tidal volume that has declined to 375 mL. Oxygen saturation has fallen to 92%.
Arterial blood gas is pH 7.42, PaCO2 is 45 mmHg, and PaO2 is 66 mmHg.


Which of the following statements about liberation of the patient from mechanical ventilation is true?
A. Liberation is unlikely to be successful because of an abnormally high rapid shallow breathing index
(respiratory rate/tidal volume ratio) at 30 min.
B. The patient's negative inspiratory pressure of “40 cmH2O indicates significant diaphragmatic
weakness.
C. The rise in the patient's heart rate by more than 20 beats/min is a concern because it may represent
fatigue from increased work of breathing.
D. The patient's mental state is prohibitive for extubation.
E. The patient is unlikely to maintain adequate oxygenation after extubation as predicted by the fall in oxygen saturation during the spontaneous breathing trial.

[ArchivalUser]

E.

[ArchivalUser]

E

[ArchivalUser]

e.

[ArchivalUser]

©

[ArchivalUser]

a.

[ArchivalUser]

Hi th


Welcome back

Lenthy stems yup we gotta get used to these

[ArchivalUser]

E-----

[ArchivalUser]

correct answer is C.

Several factors must be taken into account when one is considering discontinuation of mechanical
ventilation and extubation. In addition, there are several approaches to deciding who is appropriate for
extubation. Before one considers respiratory variables for extubation, an initial first step is to evaluate
whether the patient's mental status is appropriate for extubation. All sedatives should be halved or
discontinued, and the patient should be following commands. A strong cough and a strong gag response
are also desirable to prevent accumulation of abnormal secretions. Frequently upper airway patency is
also assessed by the respiratory therapist to ensure that air is able to move through the airway when the
endotracheal tube cuff is deflated. Measures of ventilatory function are also important before extubation
to assess whether the patient will be able to maintain spontaneous respiration. The most commonly used
tool to determine whether a patient is an appropriate candidate for extubation is the
rapid-shallow-breathing index. This is calculated by dividing the respiratory rate by the tidal volume in
liters. A value above 105 breaths/min per liter is highly predictive of failure to be successfully extubated,
with a sensitivity between 72 and 97%. However, a ratio less than 105 does have many false positives,
and this index alone should not be used to decide on extubation. Many experts recommend using this as
a guide for who should undergo a spontaneous breathing trial for 30 to 60 min. An inspiratory pressure
greater than “30 cmH2O and a vital capacity greater than 10 mL/kg are also good indicators of
diaphragmatic and chest wall function and are desirable before extubation. Alveolar ventilation is
generally adequate for extubation when pH can be maintained between 7.35 and 7.40. However, a
minute ventilation above 20 L/min is worrisome. Similarly, oxygenation should be maintained during a
spontaneous breathing trial and can be predicted by maintenance of an SaO2 above 90% or a PaO2
below 60 mmHg while the patient is on an FIO2 less than 0.5 and a PEEP less than 5 cmH2O. Other
markers of increased work of breathing should be monitored as well. A rise in heart rate greater than 20
beats/min or in systolic blood pressure more than 20 mmHg may signify prohibitive work of breathing
and indicate that the patient should be carefully evaluated before extubation.