ch 11 & 12

self assessment questions

The ascending ramp and sine flow waveforms are not used for positive pressure ventilation because the initial flow rate is _______ for most patients. These two waveforms may be appropriate for _______ ventilation.

not sufficient, control

2. In volume, pressure and flow waveforms, time in seconds is displayed along the _______ axis.

x- or horizontal

Tidal volume can be calculated or determined by measuring the _______ under a _______ waveform.

area, flow/time

The area enclosed under the expiratory flow waveform should _______ the area under the inspiratory flow waveform. If the expiratory volume is less than the inspiratory volume, _______ may be present

be equal to, circuit leak or gas trapping

In assist/control mode, the I:E ratio is variable because the _______ time of a breath is dependent on the beginning of the _______ breath.

expiratory, following

. On a pressure waveform, PEEP is present when the end-expiratory pressure rests:

above 0 cm H2O.

On the pressure waveform, assist effort is present when the trigger pressure reaches the _______ setting.

sensitivity

In CPAP mode, there are no _______ breaths and the airway pressure is above _______ cm H2O.

mechanical, 0

An increase in inspiratory flow or airflow resistance would show an unchanged _______ but increased _______. (See Figure 11-11.)

PALV, PIP and PTA

A decrease in total compliance (CLT) would show an unchanged _______ but increased _______. (See Figure 11-12.)

PTA, PIP and PALV

When the flow waveform selection is changed from constant flow to true descending ramp while holding inspiratory time constant, the same volume can only be maintained if the peak flow of the descending pattern is:

doubled

When the flow waveform selection is changed from constant flow to true descending ramp during VCV, the same volume can only be maintained if the inspiratory time of the descending pattern is:

doubled

With time-limited ventilation, the higher initial peak flow for the descending ramp flow wave creates a _______ initial flow resistive pressure (PTA) than the PTA created by the constant flow. (See Figure 11-14.)

higher

With flow-limited ventilation, the initial flow-resistive pressure (PTA) is the same for the _______ flow waves. The initial peak flow level stays the same for _______ flow during flow-limited ventilation. (See Figure 11-14.)

constant and descending ramp, constant and descending ramp

In constant flow and descending ramp flow ventilation, the rise in alveolar pressure (PALV) is directly related to _______ and inversely related to _______.

volume delivery, compliance

At constant TI, a decreased flow leads to (See Figure 11-15):

lower VT, PTA, and PALV

During descending ramp flow ventilation, a higher end-flow leads to a _______ VT and PTA and it _______ affect the PALV. (See Figure 11-16.)

larger, does not

When peak flow is constant (square), _______ are _______ related

VT, TI and PALV; directly

In pressure-controlled ventilation, _______ are typically set by the operator

pressure level, rate, and I:E ratio

In pressure-controlled ventilation, the flow level and VT delivered are primarily dependent on the:

pressure level set and lung characteristics

During inverse ratio pressure-controlled ventilation, the patients are usually sedated and paralyzed in order to prevent:

dyssynchrony with the ventilator

In pressure support ventilation, only the _______ level is set and under normal condition, _______ are primarily under the patient’s control.

pressure support, flow, volume and inspiratory time

During pressure-controlled ventilation, a(n) _______ airflow resistance or _______ compliance would reduce the delivered flow and tidal volume.

increased, decreased

Tachypnea, agitation, accessory muscle use, active expiration, muscle fatigue, and respiratory failure are signs of:

patient-ventilator dyssynchrony

On a flow waveform, failure of the expiratory flow to return to baseline is indicative of _______ and this condition may lead to _______ and possibly auto-PEEP.

incomplete expiration, gas trapping

In the presence of excessive airway resistance, the expiratory flow is _______ and the expiratory time is _______.

decreased, prolonged

A decreased CLT leads to a higher expiratory peak flow, a _______ PIP, and a _______ expiratory time

higher, shorter

A delay of positive pressure waveform (i.e., lack of ventilator response) in spite of a normal negative pressure waveform (i.e., good patient effort) is indicative of

dysfunction of the inspiratory valve or sensitivity setting.

Failure of the expiratory flow to return to the zero baseline is indicative of

gas leak or air trapping

When a circuit leak occurs in the presence of PEEP, pressure in the circuit drops to the sensitivity setting below the PEEP level and _______ develops and leads to extremely _______ mechanical breaths.

autotriggering, slow

The difference between PAO and PALV is: (See Figure 11-38.)

PTA

On a volume-pressure curve, the _______ is assumed to be stable and unchanged if PALV rises linearly with increases in volume. (See Figure 11-38.)

CLT

On a pressure-volume loop, a reduction in CLT causes the loop to move toward the (See Figure 11-39):

pressure axis

On a pressure-volume loop, a reduction in CLT will not change the PTA because the gradient between _______ remains the same. (See Figure 11-39.)

PIP and PALV

On a pressure-volume loop, an increase in resistance would not affect the _______ while the _______ are increased. (See Figure 11-40.)

. PALV; PTA, PIP, and PAO

The initial point of inflection (Ipi) occurs when alveoli are recruited during _______. In the presence of Ipi, _______ can be added slightly above the pressure at the inflection point to prevent the alveoli from closing during expiration. (See Figure 11-41.)

inspiration, PEEP

Overinflation of the alveoli causes a(n) _______ in CLT leading to the appearance of an upper inflection point (Ipu). The Ipu can be minimized by reducing the _______. (See Figure 11-42.)

decrease, tidal volume

On a flow-volume loop, the expiratory flow is _______ the horizontal (volume) axis and it is usually _______ following a successful bronchodilator therapy. (See Figure 11-43.)

below, increased

Strategies that are useful to improve ventilation include all of the following except:

increase mechanical deadspace

Dr. McFarland asks the therapist to adjust the ventilator in order to improve the oxygenation status of the patient with normal V/Q status. Which of the following ventilator adjustments would have the most direct effect on oxygenation?

increase FiO2

An endotracheal tube is sometimes shortened because a shorter ET tube:

facilitates airway management and secretions removal

The primary purpose of permissive hypercapnia is to reduce the patient’s _______ during mechanical ventilation.

pulmonary pressures

Permissive hypercapnia is a technique in which the mechanical _______ is reduced. This change is done intentionally to increase a patient’s _______.

tidal volume, pH

CPAP and PEEP may be used to reduce or correct refractory hypoxemia caused by:

intrapulmonary shunting

The PaO2 of a spontaneously breathing patient has been deteriorating while on 60% of oxygen via a partial-rebreathing mask. The physician asks the therapist to suggest the best solution for this problem. The therapist should recommend the following procedures in the order provided:

CPAP, mechanical ventilation with PEEP, inverse ratio ventilation

Compensated respiratory acidosis and compensated metabolic alkalosis have similar blood gas characteristics: normal pH, high PaCO2, and high HCO3 -. One useful clue to differentiate these two conditions is that in compensated:

respiratory acidosis, the pH is on the acidotic side of normal range.

A patient’s low pressure alarm is triggered persistently. The likely causes of this condition include all of the following except:

kinking of the ET tube

During patient rounds in the ICU, the high pressure alarm of a ventilator is triggered. This condition is likely caused by:

patient coughing

Analysis of sputum samples by the culture and sensitivity method is _______. It provides information on the type of _______ that the microbes are sensitive to.

time-consuming, antibiotics

The urine output of a patient is about 15 mL/hour. This volume of urine output is _______ than normal and it implies that there is too _______ fluid in the extracellular fluid compartment.

lower, little

The following electrolyte values are collected from a patient with severe sepsis who has been on a mechanical ventilator for 2 weeks. Which of the following electrolytes is out of normal range?

Na+ 138

K+ 1.5

Cl- 105

HCO3 25

K+ 1.5

. In replacing fluids to a volume-depleted patient, it is not safe to administer fluids that have no sodium because _______ movement of sodium-free fluid into the brain and kidney cells may cause _______ of these organs.

rapid, swelling

Decreased muscle function, flattened T wave and depressed ST segment on the electrocardiogram, and diminished bowel sounds are some signs of:

hypokalemia

Proper nutrition is essential to patients receiving mechanical ventilation because undernutrition can cause:

fatigue of respiratory muscles

A diet consisting of low carbohydrate and high fat is more suitable for ventilator patients because _______ generates more calories per gram and produces less _______.

fat, CO2

The total energy expenditure (TEE) is _______ than the resting energy expenditure (REE) because TEE _______ accounts for patient factors such as activity, trauma, and infection.

higher, does

Mr. Howe, a 70-kg patient with ARDS, is being mechanically ventilated at a SIMV frequency of 12/min and tidal volume of 600 mL. Over a period of 8 hours, the peak inspiratory and plateau pressures have increased to 66 and 45 mm Hg, respectively. The attending physician asks a therapist to suggest changes to minimize the effects of rising airway pressures. The therapist should recommend initiation of:

ventilation with low tidal volume.