3C- Support Oxygenation and Ventilation

TMC: 15 questions

Low to moderate oxygen concentrations (FIO2s between 0.21 and 0.50) are generally effective in treating hypoxemia caused by which of the following?

1. Low alveolar PO2

2. Diffusion defect

3. Moderate V/Q imbalance

1 and 2

1 and 3

2 and 3

1, 2 and 3

1, 2, and 3

When hypoxemia is caused by a reduced alveolar PO2, a diffusion defect, or a moderately low V/Q ratio, normal levels of arterial oxygenation can be achieved by simple oxygen therapy techniques, usually with an FIO2 < 0.50. Low to moderate O2 concentrations are not effective in treating hypoxemia due to physiologic shunting ('refractory hypoxemia'). Treatment of hypoxemia due to physiologic shunting requires application of continuous distending pressure (PEEP or CPAP) to open collapsed alveoli and maintain their inflation.

An 84-kg (185-lb) 6-ft 1-in (185-cm) male is receiving mechanical ventilation by a volume-controlled ventilator in the assist/control mode on the following settings and corresponding ABGs:

Mandatory rate: 10/min

VT: 750 mL

FIO2: 0.6

PEEP: 5 cmH2O

pH 7.33

PaCO2 47 mmHg

PO2 78 mmHg

HCO3- 23 mEq/L

BE -1 mEq/L

Which of the following represents the most appropriate action?

add deadspace

decrease rate

increase PEEP

increase VT

increase VT

A patient with asthma receiving volume-controlled ventilation has the following arterial blood results on the settings below:

Mode Assist/control

Mandatory rate 14

VT 600 mL

FIO2 40%

PEEP 5 cm H2O

I:E 1:2

pH 7.48

PaCO2 32 torr

PaO2 81 torr

HCO3- 24 mEq/L

BE 0 mEq/L

Which of the following changes is most appropriate?

increase inspiratory flow

increase rate to 16

add 50-100 mL of deadspace

decrease rate to 10

add 50-100 mL of deadspace

This patient is over ventilating as manifested by low CO2. CO2 may be raised by decreasing mandatory rate, decreasing tidal volume, or adding deadspace. Because CO2 is only barely off of target adding 50-100 mL of dead space is most appropriate. While decreasing rate is a step in the right direction it is likely that decreasing the rate by 4 is too significant.

A tandem aerosol device is used

to deliver sufficient flowrates through large-volume nebulizers.

for patients requiring FIO2 of 0.50 or greater.

whenever the flowrate is set to 15 L/min or above.

on patients with croup

to deliver sufficient flowrates through large-volume nebulizers.

A tandem aerosol device is used when only one device is incapable of producing enough total gas flow to meet or exceed the patient's inspiratory demand.

The primary goal of O2 therapy is to:

decrease the work of breathing

decrease myocardial workload

improve tissue perfusion

correct arterial hypoxemia

correct arterial hypoxemia

If a sudden tension pneumothorax is experienced on a volume-cycled mechanically ventilated patient, the respiratory therapist should expect an increase in

cardiac index

A-aDO2

static compliance

RAW

A-aDO2

A-aDO2 will increase with a pneumothorax because delivered oxygen will have less functional surface area in the pulomnary capllary membranes to diffuse into the ciculatory system. The air trapped in the pleural space pushes against the lung, limiting the lung's ability to expand and utilize all areas of the lung parynchema. The large "A" referes to the Alveolar oxygen tension, while the small "a" refers to arterial oxygen tension in the blood.

You observe the following graphics display on a patient receiving volume controlled A/C ventilation. The most significant problem is:

a leak in the patient-ventilator system

inadequate inspiratory flow setting

improper sensitivity setting

presence of auto-PEEP/air-trapping

inadequate inspiratory flow setting

A febrile patient is receiving non-invasive positive pressure ventilation with an IPAP of 26 and an EPAP of 10 cmH2O. The following uncorrected blood gas data on these settings is available:

pH 7.32

PaCO2 48 mm Hg

PaO2 80 mm Hg

HCO3- 24 mEq/L

BE 0 mEq/L

Which of the following change is most appropriate?

decrease EPAP

increase IPAP and EPAP

increase IPAP

maintain settings

increase IPAP

Directing a cool oxygen mixture to an infant in an oxyhood can result in which of the following?

increased peripheral perfusion

decreased metabolic rate

increased oxygen consumption

decreased convective heat loss

increased oxygen consumption

A patient develops air trapping/auto-PEEP during positive pressure ventilation. This will tend to increase

baseline airway pressure

patient-ventilator synchrony

pulmonary blood flow

work of breathing

work of breathing

Air trapping/auto-PEEP increases alveolar pressures, thereby impeding pulmonary blood flow, increasing pulmonary vascular resistance and increasing the possibility of pulmonary barotrauma. Auto-PEEP also can cause thoracic distention and flattening of the diaphragm, which can increase the work of breathing. Last, auto-PEEP can result in patient-ventilator dyssynchrony in patient-triggered modes of mechanical ventilation. Auto-PEEP generally does not alter baseline airway pressure. This is why some refer to it a 'occult' PEEP

Which of the following monitoring/alarm systems is mandatory for acutely ill patients receiving noninvasive positive pressure ventilation?

disconnect alarm

volume monitor

inversed I:E ratio

high FIO2 alarm

disconnect alarm

A patient who is hemodynamically unstable experiences a drop in cardiac output from 5.1 L/min to 3.2 L/min immediately following an increase in PEEP from 20 cmH2O to 25 cm H2O. FIO2 is currently at 0.70. The respiratory therapist should first do which of the following?

Increase FIO2 to 1.0

Increase FIO2 to 0.8

Decrease PEEP to 20 cmH2O

Discontinue PEEP

Decrease PEEP to 20 cmH2O

When a patient is receiving high levels of PEEP, the hemodynamic stability of the patient should be monitored. In this case, an increase in PEEP resulted in a decrease in cardiac output to a level that is below normal. Normal cardiac output is 4 to 8 L/min. When this happens, it is paramount that the PEEP level be decreased to its prior setting. Beyond this, to address the patient's hypoxemia, FIO2 should be increased, even if it has to be increased above 60%.

While preparing to administer a metered-dose inhaler (MDI) to a patient with COPD, the respiratory therapist notices the patient becomes unconscious and markedly cyanotic. Which of the following should the therapist immediately do?

place on a nonrebreathing mask

deliver several puffs of the MDI

page the physician

begin chest compressions

place on a nonrebreathing mask

A patient with COPD is receiving oxygen therapy at 2 L/min by nasal cannula. During a routine check, the respiratory therapist finds the patient unresponsive. The ECG waveform on the monitor is consistent with ventricular tachycardia. The therapist should immediately

Perform cardioversion

Place the patient on a nonrebreathing oxygen mask and check for a pulse

Begin chest compressions

Defibrillate at 360 joules with synchronization set to ON

Place the patient on a nonrebreathing oxygen mask and check for a pulse

An 18-hour-old, 29-week gestational age neonate is being maintained on a ventilator with an FIO2 of 0.5. The neonatologist believes that the patient has respiratory distress syndrome (RDS). The following blood gas results are obtained from an umbilical artery sample:

pH 7.35; PaCO2: 37 torr; PaO2: 49 torr; HCO3: 25 mEq/L

Based on this information, what should the respiratory therapist recommend?

Get a chest radiograph film to look for a pneumothorax

Get an ABG sample from a radial artery

Give 100% O2 in an O2 hood.

Start 5 cm H2O PEEP.

Start 5 cm H2O PEEP.

100% O2 may help to improve oxygenation. However, the patient should remain on the ventilator since an oxygen hood does not support breathing. PEEP should improve the PaO2 level since it will increase the functional residual capacity (FRC). It is indicated on the basis of low O2 and normal CO2 levels.

A patient receiving mechanical ventilation is experiencing an increase in autoPEEP. Which of the following should the respiratory therapist increase to lower autoPEEP?

mandatory rate

PEEP

flow rate

pressure support

flow rate