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127 Cards in this Set

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  • Back
What is the recommended tidal volume for mechanical ventilation in acute respiratory failure?
4 to 8 ml/kg
What gastrointestinal conditions are commonly associated with long term positive pressure ventilation (PPV)
Bleeding and Ulceration
Physiological effects of adding a volume-limited inflation hold to mandatory breaths include what?
Decreased PaCO2, Increased inspiratory time, decreased Vd/Vt
What are some characteristics of CPAP?
It maintains alveoli at greater inflation volumes. It holds airway pressure essentially constant, It has side effects similar to those of positive pressure ventilation.
What is considered safe settings for a recruitment maneuver?
Pressures up to 50 cm H2O, pressures applied for 1 to 3 minutes.
Primary indications for using PEEP in conjunction with mechanical ventilation include:
When dynamic hyperinflation occurs in COPD patients. When acute lung injury causes refractory hypoxemia.
Beneficial physiological effects of PEEP include what?
Increased PaO2 for given FIO2, Increased lung compliance (CL), Decreased shunt fraction, Increased functional residual capacity.
What is considered a normal spontaneous tidal volume?
5 to 7 ml/kg
To prevent muscle fatigue or atrophy, the level of PSV should be adjusted to achieve what work load?
0.6 to 0.8 J/L
What is a consequence of decreased resistance and compliance?
It takes less time to fill and empty the alveoli.
What factors contribute to the development of auto positive end-expiratory pressure (PEEP)
High expiratory Raw, Inadequate expiratory time
Administration of PEEP or CPAP is associated with all the of the following benefits:
Alveoli open, alveoli stable, fluid-filled alveoli open
Pressure-controlled (PC) modes of ventilatory support include all the of the following:
Pressure controlled continuous mandatory ventilation (PC-CMV), pressure controlled intermittent mandatory ventilation, volume-assured pressure-supported ventilation (VAPSV)
What mode of pressure-controlled ventilation is designed to prevent alveoli with short time constants from collapsing, thereby improving oxygenation?
Pressure-controlled inverse ratio ventilation
Which of the following are potential effects of positive-pressure ventilation on the cardiovascular system?
Decreased venous return, decreased ventricular stroke volume.
What lung unit would be most prone to air trapping?
One with high resistance and high compliance.
What does pressure-supported ventilation consist of?
Patient-triggered, pressure-limited, flow-cycled breaths
A patient receiving long-term positive-pressure support exhibits a progressive weight gain and a reduction in hematocrit. What is most likely cause of this problem?
Water retention
What are some primary uses for pressure-supported ventilation (PSV)?
Augmenting patient's spontaneous Vt. Overcoming the imposed work of breathing.
What mode of support provides all of the patient's minute ventilation (VE) as mandatory volume-controlled (VC) breaths?
VC continuous mandatory ventilation
What term describes the lung injury associated with the release of prostanoids?
In what type of ventilation is alveolar expansion during inspiration due to an increase in alveolar pressure
Positive -pressure ventilation
Positive-pressure ventilation (PPV) can reduce uninary output by how much?
30% to 50%
Compared with a square wave flow pattern, a decelerating flow waveform has what benefits?
Reduced peak pressure. less inspiratory work, decreased volume of dead space-to-tidal volume ratio (Vd/Vt)
What are characteristics of negative-pressure ventilation (NPV)?
NPV is similar to spontaneous breathing. Airway (mouth) pressure during NPV is zero, Expiration during NPV is by passive recoil, NPV decreases pressure at the body surface.
During volume-controlled continuouse mandatory ventilation, should either compliance decrease or airway resistance (Raw) increase, what will happen?
The peak airway pressure will increase.
What are some physiological advantages of volume-assured pressure-supported ventilation?
Improved patient-ventilator synchrony and decreased work of breathing.
What groups of patients are primarily affected by ventilator-associated pneumonia?
Infants, Adults older than 65 yrs, Immunosuppressed, Thoracoabdominal surgery, depressed sensorium
What variable(s) determines the level of support achieved with adaptive support ventilation?
Patient effort and time constant.
What term describes the lung injury associated with the use of low tidal volumes?
Ventricular dysfunction occurs in patients receiveing positive-pressure ventilation for all of the following reasons:
hypovolemia, excessive tidal volume, receiving more than optimal PEEP
Assuming a constant rate of breathing, what I:E ratio would tend to most greatly impair a patient's systemic diastolic pressure?
Bilevel positive airway pressure (BiPAP) is used for what purposes?
Nocturnal ventilatory support of chronic disease patients. Preventing intubation of patients wiht acute exacerbations of COPD, treatment of obstructive sleep apnea in the home. Would NOT be used for vent support in status asthmaticus
The increased work of breathing associated with auto PEEP during mechanical ventilation is due to
Hyperinflation or impaired contractility of the diaphragm, Large alveolar pressure drops required to trigger breaths
What are characteristics of positive-pressure ventilation (PPV)?
During inspiration, pressure in the alveoli increases, the pressure gradients of normal breathing are reversed, during inspiration, alveolar pressure exceeds pleural pressure.
What actions can you use to decrease compressed volume loss during mechanical ventilation?
Low-volume, Low-compliance tubing, Ventilator with minimal internal volume, Low-volume humidifier or heat-moisture exchanger.
On what does volume delivered depend during pressure-targeted modes of ventilatory support?
Set pressure limit. Patient effort
For patients with respiratory insufficiency, pressure supported ventilation (PSV) has what advantages over spontaneous breathing?
Decreased respiratory rate
Increased VT
Decreased O2 consumption
What is the explanation for the increased V/Q ratio when excessive PEEP is used?
Diversion of blood from ventilated alveoli to hypoventilated alveoli
What mode(s) of ventilatory support is used to help decrease airway and alveolar pressure?
Pressure-controlled continuous mandatory ventilation.
The volume of gas actually delivered to a patient by most positive pressure ventilation is always less than that expelled from the machine. What factors help explain this?
Gas compression under pressure.
Presence of built-in leaks
Expansion of the ventilator circuitry
What variables determine the level of support achieved with adaptive support ventilation?
Patient effort
Resistance of the endotracheal tube
During volume assured pressure supported ventilation, the breath will be pressure limited under what conditions?
The delivered tidal volume (Vt) is greater than the preset minimum Vt.
When bedside work of breathing measures are unavailable, you should adjust the level of pressure-supported ventilation (PSV) to what breathing pattern?
Spontaneous rate 15 to 25/min. Vt 5 to 8 ml/kg
Ventilatory support strategies likely to result in auto PEEP include:
Continuous mandatory ventilation (CMV) assist-control. Inverse ratio ventilation (IRV). Low Inspiratory flows. NOT low-rate intermittent mandatory ventilation.
Volume-controlled (VC) modes
of mechanical ventilation include:
VC continous mandatory ventilation. VC intermittent mandatory ventilation.
What patients are at greatest risk for auto PEEP?
Those with high airway resistance. Those with high expiratory flow resistance
What conditions are associated with a lack of response to increased FIO2 in patients receiving positive-pressure ventilation?
Factors that would tend to increase mean airway pressure
Increased mandatory breaths. Increased levels of positive inspiratory pressure (PIP). Increased levels of positive end expiratory pressure (PEEP)
What condition does not require high mechanical respiratory rates?
Metabolic alkalosis
What ventilator is controlled by fluidic logic systems?
Sechrist IV-100B
What are major categories of ventilator function are useful in classifying ventilators?
Control scheme, Power conversion, Ventilator output
When setting the tidal volume on a patient being mechanically ventilated, what criteria should be kept in mind?
It should never cause the plateau pressure to exceed 30 mm Hg.
What would you assess immediately after a patient is placed on a ventilatory support device?
ABG's, Patient airway, Patient's vital signs
A patient receiving continuous mandatory ventilation in the assist-control mode develops auto-PEEP. What changes in ventilatory patterns would you consider to minimize the effects of auto-PEEP in this patient?
Decreasing the rate or increasing the Vt. Using low-rate synchronized intermittent mandatory ventilation. Lowering the Vt and letting the PaCO2 rise
To prevent atelectasis and improve gas exchange, most thorasic surgery patients placed on ventilatory support receive how much PEEP?
5cm H2O PEEP
On some ventilators, what can a trigger setting that is too sensitive cause?
In which of the following clinical situations is the incidence of auto-PEEP the greatest?
Patients with high respiratory rates. Intubated patients with obstructive lung disease.
What will most likely result if the patient ventilated in the assist-control mode develops a high ventilatory drive?
Respiratory alkalosis
What factors can have a major impact on adult patient-ventilator interation?
Humidification system.
PEEP valve function
Trigger sensitivity
NOT tubing compliance
Which of the inspiratory flow patterns would result in the lowest peak inspiratory pressure?
Decelerating flow pattern
What mode of ventilation will automatically vary the pressure support provided as patient effort changes to maintain a "normal" work of breathing?
Proportional assist ventilation (PAV)
On a ventilator that has separate rate and minute ventilation (VE) controls, the rate is set at 13/min. and the VE at 11L/min. About what Vt is the patient receiving?
850 ml
What goal(s) does the practitioner hope to achieve when selecting intial ventilatory support settings?
Optimize oxygenation
Optimize ventilation
Maintain acid-base balance
Avoid harmful side effects
Compared with a volume-cycled strategy, what are some potential advantages of pressure-targeted ventilatory support?
Limit and control of peak airway pressures. Provision of a decelerating flow pattern.
What is the primary advantage of negative-pressure ventilation?
No need for artificial airway.
What limits should be initially set for high and low Vt values and/or minute volume alarms on a ventilatory support device?
+/- 10% to 15%
What mode(s) of ventilatory support would you initially recommend for a patient whose compliance or resistance is likely to change rapidly?
Volume-targeted CMV
When titrating the FIO2 level downward from 100% to 40%, what is the maximum increment that should be applied between estimates of oxygenation?
For adults with otherwise normal lungs who are receiving ventilatory support in the continuous mandatory ventilation control or assist control mode, inpiratory flow should be set to provide what I:E?
After placing a patient on ventilatory support, how long should you wait before drawing a sample for measurement of the ABG to ensure proper equilibration between alveolar and arterial gas tensions.
30 minutes
Immediately after cardiac arrest and resuscitation, a patient is placed on a ventilator in the continous mandatory ventilation assist-control mode. What initial FIO2 would you recommend?
When adjusting the FIO2 setting for a patient receiving mechanical ventilatory support, what should your goal be?
Decrease the FIO2 to below 0.50 as soon as possible
What is the recommended range for the tidal volume for the intial ventilator settings in the volume control mode?
8 to 10 ml/kg
Air-trapping is a major concern in patients with what diagnosis when using the assist control mode?
Chronic obstructive pulmonary disease (COPD)
What percentage of mechanical ventilated patients has a tracheostomy tube placed at some point?
For adolenscents in the 8 to 16 year old range, what ranges of ventilator settings would you initially recommend?
Rate 20 to 30/min. Vt 8 to 10 ml/kg
Causes of hypoxemia:
Ventilation/perfusion (V/Q) mismatch. Shunt. Alveolar hypoventilation. Diffusion/perfusion impairment. Decreased inspired O2. Venous admixture
Clinical signs suggesting a more severe hypoxemia?
CNS dysfunction ranging from irritability to confusion to coma. A "white" chest xray is evident when alveoli are partially occluded.
Clinical signs associated with hypoxemia due to shunt:
a "white" chest radiograph. Lack of increase in PO2 as FIO2 is increased
Clinical signs of interstial lung disease with hypoxemia due to diffusion defect:
Dyspneic patient with a dry cough and fine basilar crackles. Clubbing of the nail beds. Pulmonary hypertension may be present. Signs of edema, jugular vein distension.
V/Q mismatch and shunt:
Both result in elevated P(A-a)O2 levels indicating that the hypoxemia is due to an abnormality of lung tissue.
Normal values for P(A-a)O2 range:
10mmHg in the young and to 25mmHg in the elderly while breathing room air
What are the three basic methods for discontinuing ventilatory support?
Spontaneous breathing trials (SBTs). Synchronized intermittent mandatory ventilation (SIMV). Pressure support ventilation (PSV)
Hypoxemia commonly presents with?
Dyspnea, tachycardia, and tachypnea. The use of accessory muscles. Leaning forward on his/her arms. Nasal flaring.
Disease associated with perusion/diffusion impairment?
Liver disease
Common cause of low mixed venous oxygen?
Congestive heart failure with low cardiac output.
Treatment of intrapulmonary shunt:
Directed toward opening collapsed alveoli or clearing fluid or exudative material before O2 can be beneficial at below toxic levels.
Causes of hypercapnic respiratory failure (ventilatory failure)
Decreased ventilatory drive. Neurologic diseases. Increased work of breathing.
Guillain-Barre syndrome:
lower extremity weakness progressing to the respiratory muscles in 1/3 of patients. Weak cough and gag can be seen.
Myathenia gravis:
Ocular muscle weakness - can exhibit bulbar weakness on its path to respiratory muscle failure.
Distinguish chronic hypercapnic respiratory failure from acute hypercapnic respiratory failure?
Chronic - elevated PaCO2 and elevated HCO3, normal pH.
Acute - will have an elevated PaCO2 but normal HCO3 and pH will be low.
What is the cardinal sign of increased work of breathing?
Tachypnea is the cardinal sign of WOB.
Vital capacity (VC ml/kg):
Normal = 65 to 75 Support is needed when <10
Normal work of breathing:
0.3 to 0.6 J/L
In intubated patients what are sources of imposed work of breathing?
endotracheal tube, ventilator circuit and auto-PEEP due to hyperinflation with airflow obstruction.
Normal Minute Ventilation
5 to 6 L/min. A VE above 10L/min is cause for concern.
Normal respiratory rate (adults)
12-20 breaths/minute
Rates exceeding 35 breaths/min. for extended periods are a signal of inadequate alveolar ventilation or hypoxemia. This eventually will lead to respiratory muscle fatigue.
Standard criteria for instituting mechanical ventilation:
Apnea or absence of breathing.
Acute respiratory failure.
Impending respiratory failure. Refractory hypoxic respiratory failure with increased WOB or an effective breathing pattern.
Normal VD/Vt range is:
0.3 to 0.4 at normal tidal volumes.
Normal PaO2
80 to 100 mmHg on room air. A PaO2 <70 mmHg (or SpO2 <90%) on an O2 mask (FIO2 > 0.6) indicates inadequate oxygenation or lung failure.
What is the definition of "mandatory breaths" with regard to mechanical ventilation?
Mandatory breaths are breaths for which the ventilator controls the timing or tidal volume (or both). A patient-triggered, volume targeted, volume cycled breath is a mandatory breath. The machine controls tidal volume.
What is the definition of "spontaneous breaths" with regard to mechanical ventilation?
The patient controls the timing and the tidal volume. The volume or pressure (or both) delivered is based on patient demand and the patient's lung characteristics, not on a set value.
Assisted breaths:
Characteristics of both mandatory and spontaneous breaths. All or part of the breath is generated by the ventilator, which does part of the work of breathing.
In patients suffering from acute respiratory acidosis, below what pH level are intubation and ventilatory support generally considered?
What indicators are useful in assessing respiratory muscle strenth?
Maximum voluntary ventilation. (MVV)
Forced Vital Capacity (FVC)
Maximum inspiratory pressure (MIP)
In intubated patients what sources of increased imposed work of breathing include?
Endotracheal tube
Ventilator circuit
What diseases are associated with hypercapnic failure due to work of breathing?
A patient develops acute respiratory failure due to muscle fatique. What modes of ventilatory support would be recommended?
Assist control ventilation with adequate back up
Synchronized intermittent mandatory ventilation with adequate back-up rate
Bilevel pressure support by mask
Hypoxemia can be caused by:
Diffusion impairment
Alveolar hypoventilation
V/Q mismatch
Intrapulmonary shunting
what vent mode would you suggest for a severly hypoxemic patient with acute lung injury or ARDS?
Pressure-controlled ventilation
What are some causes of dynamic hyperinflation?
Increased airway resistance
Decreased expiratory flow rate
What best helps to distinguish chronic hypercapnic respiratory failure from acute hypercapnic respiratory failure?
Kidneys retaining bicarbonate to elevate the blood pH
Ventilatory support may be indicated when the VC falls below what level?
A patient can generate an MIP of -18cmH2O. Based on this information, what might you conclude?
The patient has inadequate respiratory muscle strenth
What is the most common cause of low mixed venous O2?
Cardiac disease
What clinical sign suggests more severe hypoxemia?
central nervous system dysfunction
When is respiratory muscle fatigue likely to occur?
When VE exceeds 60% of MVV
What is a feature of Guillain Barre?
Ascending muscle weakness
A patient with interstial lung disease who presents with hypoxemia due to diffusion defect would have what clinical signs?
Fine bibasilar crackles
Clubbing of the finger nail beds
Jugular venous distention
Increased P2
Hypercapnic (typeII) respiratory failure is a synonym for what term?
Ventilatory Failure
What is the optimal treatment of intrapulmonary shunt?
Alveolar recruitment
What measures should be used in assessing the adequacy of a patients alveolar ventilation?
Arterial pH
What are some characteristics regarding "acute-on-chronic" form of respiratory failure?
It is most common with patients with COPD
Bacterial or viral infections are common precipitating factors
Mortality is associated with severity of acidosis
What is the normal rate for PaO2/FIO2?
What is the normal range of Maximum inspiratory pressure (MIP) generated by adults?
-80 to -100 cmH2O
What best describes the difference between V/Q mismatch and shunt when supplemental O2 is administered?
V/Q mismatch will respond well but shunt will not