Test 1 Flashcards
Define NIV.
The delivery of mechanical ventilation to the lungs using techniques that don’t require an endotracheal airway.
What are the three basic methods of applying NIV?
- Negative-pressure ventilation
- Positive-pressure ventilation
- Abdominal-displacement ventilation
Explain how negative pressure ventilators work.
The negative pressure is transmitted across the chest wall, into the pleural space, and into the intraalveolar space. Resulting in an increase in transpulmonary pressure causing air to enter the lungs.
List the clinical benefits of NIV in the chronic care setting. (4)
- Prolongs survival
- Improves duration and quality of sleep
- Alleviates symptoms of chronic hypoventilation
- Improves functional capacity
List 5 symptoms of chronic hypoventilation.
- Fatigue
- Morning headache
- Daytime hypersomnolence
- Cognitive dysfunction
- Dyspnea
What clinical indicators demonstrate improvement in patient comfort?
- Decreased respiratory rate
- Reduced inspiratory muscle activity
- Synchronization with the ventilator
What tidal volume range should be used with NIV and how is it manipulated?
5-7 mL/kg or greater. Volume is manipulated by increasing the difference between IPAP and EPAP. This is usually accomplished by increasing the IPAP.
What are the typical ranges for the inspiratory and expiratory settings on the BiPAP?
- IPAP: 2-30 cm H2O
- EPAP: 2-20 cm H2O
What role does NIV play in “end of life” situations?
- May relieve dyspnea
- Reduce sedation requirement
- Preserve patient comfort.
List four clinical disorders that manifest in chronic respiratory failure and require NIV as supportive therapy.
- Acute exacerbation of COPD
- Hypoxemic respiratory failure
- Community-acquired pneumonia
- Cardiogenic pulmonary edema
Describe how the use of NIV in the acute respiratory failure improves gas exchange.
By resting respiratory muscles and increasing alveolar ventilation.
What are some clinical benefits of NIV in the acute care setting? (7)
- Reduces need for endotracheal intubation
- Reduces incidence of VAP
- Shortens stay in the ICU
- Reduces mortality
- Improves patient comfort
- Reduces need for sedation
- Preserves physiological airway defenses
What is the physiological goal of NIV in ARF?
Improve gas exchange by resting respiratory muscles and increasing alveolar ventilation.
Invasive ventilation has been shown to be an effective and often necessary method to support alveolar ventilation; however, there are associated risks that can often result in ________________.
- Increased mortality and morbidity
- Higher financial cost
Use of negative pressure ventilators peaked during a world wide _____________ that peaked in the 1950s.
Polio epidemic
Negative pressure ventilators are also known as ________________.
Body ventilators
Negative pressure ventilators operated on the principle of _________________.
Increasing lung volumes by intermittently applying negative pressure to the entire body below the neck or just to the upper region of the chest. Exhalation is passive and depends on the elastic recoil of the lungs and chest wall.
The first successful negative pressure ventilator is commonly referred as the ____________.
Iron lung
Exclusion criteria for NIV (8)
- Hemodynamic instability
- Excessive secretions
- Agitated or confused patients
- Inability to protect airway
- Brain injury with unstable respiratory drive
- Uncooperative or unmotivated patients
- Facial deformities
- Respiratory arrest or the need for immediate intubation
Pressure targeted ventilators are __________-limited, ____________-triggered and ___________-cycled ventilators.
- pressure-limited
- flow and time-triggered
- time-cycled
What is shown to be effective in the treatment of acute cardiogenic pulmonary edema (ACPE)?
- Bilevel NIV
- CPAP
What were some cons of the negative pressure ventilators?
- Lack of portability
- Difficulty in providing routine nursing care
What form of positive pressure ventilation is known to be effective in the treatment of obstructive sleep apnea?
CPAP
____________ is considered by most clinicians to be a lifesaving application of ARF.
Noninvasive ventilation
Endotracheal intubation is associated with complications such as what? (4)
- Airway trauma
- Increased risk for aspiration
- VAP
- Patient discomfort, typically requiring the use of sedatives
Such complications can lead to a longer hospital stay, higher mortality rate and increased healthcare costs.
What is the primary goal of NIV in the acute care setting?
Avoid the need for endotracheal intubation and invasive ventilation.
Pressure support facilitates inspiration, thus ________________.
Increasing the tidal volume
NIV reduces diaphragmatic pressure swings, which suggest that ________________.
The respiratory muscles are being rested.
When PEEP is applied during PSV, PEEP helps _______________, thereby reducing the work required to initiate inspiration.
Offset auto-PEEP
Resting of the respiratory muscles and improved VT lead to what? (3)
- Lower PaCO2
- Better oxygenation
- Decreased respiratory rates
During an acute exacerbation of COPD, increased airway resistance and an increased respiratory rate lead to what?
Hyperinflation, development of auto-PEEP (air trapping) and alveolar hypoventilation.
What are some conventional medical therapies used COPDs that have an acute exacerbation?
- Bronchodilators
- Antiinflammatory agents
- Antibiotics
- Supplemental oxygen
In chronic respiratory failure, NIV is considered to be a ________________ rather than a lifesaving treatment.
Supportive therapy
Which was the first group of patients to be successfully converted from invasive ventilation to NIV?
Patients with neuromuscular disorders
Several disorders associated with nocturnal hypoventilation include: (4)
- CSA
- Obesity hypoventilation syndrome
- OSA combined with COPD
- CHF
These disorders may lead to daytime CO2 reention
If OSA continue to experience hypoventilation and nocturnal desaturation, what is typically indicated next?
NIV
The first step in establishing the need for ventilatory assistance is based on what clinical and blood gas criteria?
- P/F ratio less than 200
- pH less than 7.35, CO2 greater than 45
- tachypnea
- use of accessory muscles
- paradoxical breathing
Indications for NIV (9)
- Acute exacerbation of COPD
- Acute asthma
- Hypoxemic respiratory failure
- Community-acquired pneumonia
- Cardiogenic pulmonary edema
- Immunocompromised patients
- Postoperative patients
- Postextubation
- “Do not intubate”
What mode is this?
Patient breaths spontaneously at a set baseline pressure.
CPAP mode
Pressure-targeted ventilators (PVTs) are designed to increase minute ventilation and improve gas-exchange capabilities by ________________.
Using the delivery of an IPAP and EPAP.
What does the patient control in CPAP mode?
Rate and depth of breathing
With pressure support ventilation, the difference between the two pressure levels determines _________________________.
The level of pressure support for each assisted breath
A change to the set IPAP only occurs when?
In response to the patient’s inspiratory effort
What does the clinician set for S/T mode (older models may use the term A/C)? (3)
- IPAP and EPAP
- Respiratory rate
- Inspiratory time
In all modes, the patient’s delivered VT depends on what? (4)
- The gradient between the IPAP and EPAP level
- inspiratory time
- patient inspiratory effort
- patient’s lung characteristics (airway resistance and lung compliance)
Average volume-assured pressure support devices automatically adapt pressure support to match a patient’s ventilatory need by doing what?
Delivering an average tidal volume based on the patient’s condition.
To prevent CO2 rebreathing, EPAP level should be set at ______________ so adequate gas exchange can flush CO2 from the breathing circuit.
4 cmH2o or higher
What are the two most common disadvantages of the nasal mask?
- Air leaks
- Skin irritation
The most significant disadvantage of using acute care ventilators is _________________.
The inability of some machines to compensate for leaks.
What does BiPAP help manage?
Oxygenation (O2)
Ventilation (CO2)
What does CPAP help with?
Oxygenation only
On a BiPAP, what controls the CO2?
IPAP (VT/PIP)
On a BiPAP, what controls the O2?
EPAP (PEEP)
How do you increase O2 on BiPAP?
Increase EPAP
How do you decrease O2 on BiPAP?
Decrease EPAP
How do you correct a high CO2 on BiPAP?
Increase IPAP to blow of CO2
How do you correct a low CO2 on BiPAP?
Decrease IPAP to retain CO2
If you’re adjusting a patient’s mask and its not correcting a leak issue, what is likely the problem?
Wrong size
How do you increase oxygenation on CPAP?
- Increase FiO2 and pressure (PEEP)
Inspiratory time is determined by what? (4)
- Pressure setting
- Flow rate
- Lung compliance
- Airway resistance
Decreased compliance ____________ volume.
Increase or decrease?
Decreases
Increased compliance ____________ volume.
Increase or decrease?
Increases
Decreased airway resistance ____________ volume.
Increase or decrease?
Increases
Increased airway resistance ____________ volume.
Increase or decrease?
Decreases
What happens if you increase the sensitivity dial?
It will make the machine less sensitive to patient inspiratory trigger.
What happens if the patient effort dial is set too low?
May cause auto-triggering.
For negative pressure ventilators, exhalation was passive and dependent on _________________________.
The elastic recoil of the lung and chest wall
The iron lung was designed in 1928 by who?
Phillip Drinker and Dr. Charles McKhann
Caution should be used when non-COPD patients with pneumonia are treated with NIV.
Something to know.
What is the recommendation for treating acute cardiogenic pulmonary edema?
CPAP (10-12 cmH2O). NIV should be used in patients who continue to be hypercapnic and dyspneic thereafter.
_________________ can have certain clinical benefits for patients with chronic hypoventilation disorders.
Nocturnal use of NIV (4-6 hours)
What is the argument against using NIV on DNI patients?
Prolongs dying process, adds to patient discomfort and consumes valuable resources.
In the acute care setting, the selection process for NIV is based on what? (3)
Patient’s diagnosis, clinical characteristics and the risk for failure
Portable homecare pressure-targeted ventilators are ____________-controlled ventilators.
Micropressor-controlled, electrically powered units that use a blower to regulate gas flow into the patient circuit.
Explain S/T mode.
The patient may initiate breaths that are supported to the IPAP level, but if patient fails to make inspiratory effort within a set interval, machine triggers inspiration to the set IPAP level.
The highest pressure recorded at the end of inspiration is called:
Peak Inspiratory Pressure or Peak Airway Pressure, Peak pressure
Normally, two types of forces oppose inflation of the lungs. What are they called?
- Elastic forces
- Frictional forces
_______________ is a measurement of the frictional forces that must be overcome during breathing.
Resistance
Airway resistance is increased or decreased when an artificial airway is inserted?
Increased
The product of compliance and resistance is called a _______________.
Time constant
For air to flow through a tube or an airway, what must exist?
Pressure gradient
Transrespiratory pressure has two components. What are they?
- Transthoracic pressure
- Transairway pressure
The primary variable the ventilator adjusts to achieve inspiration is called the ________________.
Control variable
What are the most commonly used control variables?
Pressure and volume
What are some predictors of success with NIV? (8)
- Higher level of consciousness
- Younger age
- Less severe illness; no comorbidities
- Less severe gas exchange abnormalities
- Intact dentition
- Minimal air leakage around the interface - Lower quantity of secretions
- Absence of pneumonia
What may be the most significant indicator of success or failure to NIV?
Patient’s initial response to NIV
Duration of ventilatory assistance depends on what?
How quickly the cause of respiratory failure can be reversed.
What is the ventilator mode of choice for chronic respiratory failure caused by restrictive thoracic disorders in patients who can protect their airway?
NIV
NIV increases VT, reduces diaphragmatic activity and improves oxygen in some patients with CF who have _______________.
Acute exacerbations
The therapy of choice for OSA is CPAP, but if the patient continues to hypoventilate despite CPAP therapy, what may improve daytime gas exchange and symptoms associated with chronic hypoventilation?
NIV
What provides a viable weaning alternative for patients who demonstrate respiratory muscle fatigue postextubation?
NIV
What type of patients are not viewed as good candidates for ET intubation and mechanical ventilation?
DNI patients, patients with terminal and advanced disease who develop ARF.
Chart 19.1 - Pg. 360
What are symptoms indicating the need for NIV? (4)
- Moderate to severe dyspnea
- RR greater than 24 breaths/min
- Accessory muscle use
- Paradoxical breathing
NIV may be unnecessary for patients with ________ respiratory distress.
Mild
Also not appropriate for patients who have already deteriorated to severe respiratory failure because it may delay lifesaving intubation and ventilation.
____________________ MUST be considered before NIV initiated.
Reversibility of the disease process
___________________ involves the exchange of oxygen and carbon dioxide between an organism and its environment
Respiration
___________________________ is the pressure difference the alveolar space and the pleural space.
REMEMBER THERE ARE TWO NAMES
Transpulmonary pressure or transalveolar pressure
_______________________ is the pressure difference between the airway opening (mouth) and the alveolus .
Transairway pressure
____________________________ is the pressure difference between the alveolar space or lung and the body’s surface.
Transthoracic pressure
______________________ is the pressure in the potential space between the parietal and visceral space.
Intrapleural pressure
Airway opening pressure is most often called __________________________ or __________________________.
Mouth pressure or airway pressure
_________________________ represents the pressure required to expand or contract the lungs and the chest wall at the same time.
Transthoracic pressure
___________________________ is the pressure gradient required to produce airflow in the conductive airways.
Transairway pressure
______________________ is the pressure difference between the airway opening and the body surface.
Transrespiratory pressure
What two parameters are often used to describe the mechanical properties of the respiratory system and the elastic and frictional forces opposing lung inflation?
Compliance and elastance
One time constant should allow approximately what percentage of a lung to fill?
63%
Plateau pressure is used as a measure of _______________________.
Alveolar pressure
Air can be trapped in the lungs during mechanical ventilation if not enough time is allowed for exhalation. What is the most effective way to prevent this?
Monitor the pressure in the ventilator circuit at the end of exhalation.
When is plateau pressure measured?
End inspiration
Plateau pressure is similar to what?
Holding a breath at the end of inspiration
How do you obtain plateau pressure measurements?
By selecting a control marked “inflation hold” or “inspiratory pause”
Airway pressures are measured relative to a _______________________.
Baseline value
When PEEP is set, the ventilator prevents the patient from ________________________.
Exhaling to zero
PEEP applied by the operator is referred to as _____________________.
Extrinsic PEEP
PEEP and CPAP increases functional residual capacity. T or F?
True
What is auto-PEEP?
A potential side effect of PEEP, when air gets accidentally trapped in the lung.
When does intrinsic PEEP occur?
When a patient does not have enough time to exhale completely before the ventilator delivers another breath
High-frequency uses ______________ ventilating rates and _____________________ ventilating volumes.
- above normal ventilating rates
- below normal ventilating volumes
Positive pressure ventilation occurs when _________________________________________.
a mechanical ventilator is used to deliver air into the patient’s lungs by way of an endotracheal tube or positive pressure mask.
____________ time constants should be considered for I-time, particularly in pressure ventilation, to ensure adequate volume delivery.
Five
What happens if I-time is too long?
RR may be too low to achieve minute ventilation.
An expiratory time of less than _____ time constants may lead to incomplete emptying of the lungs.
3
This can increase FRC and causing air trapping in the lungs.
Define time constant.
The amount of time (in seconds) required for the lungs to inflate/deflate to a certain percentage of their volume
One time constant equals the amount of time it takes for ______% of the volume to be inhaled.
1 - 63%
2 - 86%
3 - 95%
4 - 98%
What are normal resistance values for intubated patients?
Approximately 6 cm H2O or higher
What are normal resistance values for unintubated patients?
0.6 to 2.4 cmH2O/(L/s) at 0.5 L/s flow.
Intrapleural pressure is usually about _____________ at the end of expiration during spontaneous breathing.
-5 cmH2O
What are some other names for airway opening pressure? (5)
- Mouth pressure
- Airway pressure
- Upper airway pressure
- Mask pressure
- Proximal airway pressure
_______________ is the pressure required to maintain alveolar inflation and is therefore sometimes called the alveolar distending pressure.
Transpulmonary pressure
The resistance to airflow depends on what? (4)
- Viscosity of the gas
- Gas density
- Length and diameter of the tube
- Flow rate of gas through the tube
The diameter of the airway lumen and flow of gas can decrease as a result of: (4)
- Bronchospasm
- Increased secretions
- Mucosal edema
- Kinks in the tube
The tendency of a structure to return to its original shape after being stretched or acted on by an outside force.
Elastance
What does increasing pressure do the I-time?
Increases
What does increasing flow do the inspiratory time?
Decreases
Increased compliance and decreased airflow resistance _______________ volume.
Increases
What happens if you decrease “patient effort dial” on a ventilator?
Makes the machine more sensitive. Can cause auto-triggering.
What is considered normal PaCO2 range for COPD patients?
50-60 mmHg
Decreasing the VT = _____________ PaCO2
Increased
- Decreases minute ventilation
- Decreases alveolar ventilation
Increasing the VT = ______________ PaCO2
Decreased
- Increases alveolar ventilation
- Increases minute ventilation
What manipulations would you make on a ventilator for a patient with a closed head injury? Why?
Increased RR. Hyperventilation reduces the blood flow to the brain which in turn, minimizes further swelling.
________________ is perhaps the single most important function a ventilator accomplishes.
Delivery of an inspiratory volume
What two factors determine the way the inspiratory volume is delivered?
The structural design of the ventilator and the mode set by the clinician
With time controller, what changes and what remains constant?
- Time remains constant
- Pressure, volume and flow curves changes as lung characteristics change.
Flow controller: What changes, what remains constant?
- Volume delivery and flow waveform remain constant and not affected by changes in lung characteristics.
- Flow is measured.
- Pressure waveform varies
Volume controller: What changes, what remains constant?
- Ventilator volume delivery and volume waveform remain constant and not affected by lung characteristic changes.
- Volume is measured.
- Volume and flow waveforms are unchanged
- Pressure waveform varies
Pressure controller: What changes, what remains constant?
- Vent maintains same pressure waveform at the mouth regardless of lung characteristic changes.
- Volume and flow vary with compliance and resistance changes.
When the vent maintains the pressure waveform in a specific pattern, the breathing is described as __________________.
Pressure-controlled
T or F. Inflation hold increases I-time.
True