Test 7 Flashcards
NIV
is a means of providing ventilatory support without an artificial airway, and it can be provided through both positive and negative pressure.
There are a multitude of different interfaces available for use during the application of NIV. The interface is selected to maximize patient comfort, which increases tolerance and compliance with therapy.
Oronasal Mask-air or gel filled cushions
Nasal Masks -keep mouth closed to maintain positive pressure
Nasal Pillows- in nostrils
Total Face Mask- reduces skin breakdown
Hybrid Mask-nasal pillows, eliminating mouth leak
Helmet- elim skin breakdown and need from sizing, CO2 retaining
Oralnasal Mask Advantages/ Disadvantages
ADVANTAGES
Better oral leak control
More effective in mouth breathing patients
DISADVANTAGES Increased dead space Causes claustrophobia increased risk for aspiration Difficulty speaking and eating Potential suffocation with ventilator malfunction
Nasal Mask Advantages/ Disadvantages
ADVANTAGES Less risk of advantages Easier Secretion Clearance Easier to speak/eat Less dead space Less claustrophobia
DISADVANTAGES Mouth Leak Higher resistance through nasal passages Less effective with nasal obstruction Nasal Irritation and rhinorrhea Upper airway dryness with mouth leak
Nasal Pillow Advantages/ Disadvantages
ADVANTAGES
Lower profile allows use of eyeglasses
Less contact with skin and reduced breakdown
Simple head straps
DISADVANTAGES Mouth Leak Higher Resistance through nasal passages Less effective with nasal obstruction Nasal Irritation and rhinorrhea Upper airway dryness with mouth leak
General guidelines suggest that if a patient fails to demonstrate improvement within
Module says 1-2 hours, cindy says .5-1 hour NIV initiation, alternatives should be considered
Indicators for NIV, first line therapy for several conditions
- COPD Exacerbation
- Acute Cardiogenic pulmonary Edema: CHF
- Resp Failure following transplantation
- Resp failure following lung resection
Strongest indicators for the use of NIV, which is a first line therapy and standard of care in this population
Acute worsening of COPD
Potential Contraindications of NIV, where the evidence doesnt support or is inconclusive regarding the use of NIV
- Acute Hypoxemic Respiratory Failure (ALI, ARDS)
- Asthma (unclear)
- Pts with do not intubate or do not resuscitate orders
- Failed extubation
Inclusion Criteria
- Resp distress with dyspnea, use of accessory muscles, and paradoxical breathing
- Resp Acidosis: ph less than 7.35 and PaCO2 greater than 45
- Tachypnea RR greater than 25bpm
- Diagnosis known to respond well to NIV (COPD, CHF, Edema)
Exclusion Criteria
- Need for airway protection, resp arrest, unstable hemodynamics, high risk of aspiration, copious secretions
- Unable to fit mask to to facial surgery or trauma, burns, anatomic lesions of upper airway
- Uncooperative pt
- Patient wishes
Which of the following are potential uses of NIV in the acute care setting?
A. Has no effect on hospital acquired pneumonia
B. Initial pt response to NIV may be an indicator of success or failure
C. Used for the tx of resp failure
D. Can prevent the need for intubation in some pts
B, C, D
NIV has been used successfully in the chronic care setting to treat chronic respiratory failure due to
restrictive lung disease, Stable COPD, and nocturnal hypoventilation, Chronic Respiratory Failure
-Full time use of NIV in the chronic care setting is most common in pts with chronic resp failure secondary to neuromuscular disease. Can serve as an alternative to tracheostomy
Goals of NIV in treating chronic conditions include:
- Decreasing symptoms (fatigue, morning headache)
- Decreasing Paco2
- Decreasing the degree of nocturnal arterial oxygenation desaturation
Which of the following are reasonable goals of NIV in the chronic care setting?
A. Reverse Disease condition
B. Prevent decreases in PaO2 while sleeping
C. Eliminate morning headache
D. Decrease Fatigue
E. Decrease PaCO2
B, C, D, E
There are many different options available when selecting a ventilator to provide NIV.
- Critical Care ventilators-Used for invasive, but modern feature NIV modes as well
- Intermediate Ventilators- Norm for transport or home MV
- Bilevel Ventilators- Specifically designed for NIV deliver IPAP and EPAP
Bilevel Ventilators
Use a single limb circuit and are designed to function in the presence of a leak, an almost unavoidable occurence during NIV
-Has a leak port proximal to the pt interface or on the interface itself
Leak port serves as
a passive exhalation port for the pt to prevent rebreathing of exhaled carbon dioxide
-Despite the presence of the leak port, if the pts expiratory flow exceeds the flow capacity of the part, rebreathing may occur
Bilevel vents provide
pressure support or pressure control ventilation.
- Pressure applied to the airway results from the combination of gas flow and leak.
- At a given pressure setting, more flow is required to maintain the pressure if the leak increases. For NIV, pressure support is a bit different than with critical care vents
For Critical Care vents, pressure
PSV is applied as additional pressure above the PEEP
In bilevel vents, pressure
IPAP and EPAP are set, with the difference between two designating the level of PS
The bilevel machines are
Pressure targeted and limited, can be flow or time triggered, and are flow or time cycled
The three modes commonly available for bilevel vents are
- CPAP (purely spontaneous)
- PSV (spontaneous with assist via IPAP/EPAP)
- Spontaneous/timed (S/T, with a set back up RR)
None of these modes allows a set Vt to be established. Tidal volume is variable and is determined by pressure settings and pt resp system compliance
CPAP
Continuous Positive Airway Pressure: purely spontaneous mode of vent. where the pt establishes the RR that occurs at the baseline pressure, which is greater than the atmospheric pressure
PSV
Through the use of IPAP and EPAP, the clinician can manipulate the level of pressure support, and thus, the tidal volume.
Increasing the gradient between IPAP and EPAP allows more Vt and vent support to be provided
-During PSV, the pt also establishes the RR. The machine senses the pts effort and based on achieving a set flow threshold, the breath is ended, allowing the pt to exhale to the lower EPAP
S/T
S/T allows bilevel IPAP and EPAP to be provided with a set backup respiratory rate. The patient can breathe above the set rate, but if they fail to initiate a breath within a designated time frame, the ventilator will trigger inspiration.
Just as in PSV, the gradient between IPAP and EPAP determines the level of support and volume achieved with each breath.
S/T mode is most often used to treat
Respiratory failure (as seen in COPD exacerbation) in an attempt to improve Ve and oxygenation while decreasing the WOB
Additional NIV settings that can be adjusted in addition to IPAP and EPAP
- Rise time
- IPAP
- Ramp and delay time controls
- FiO2
- Monitors
- Alarms
Rise Time
establishes the pressurization rate, or the period of time it takes to reach the IPAP level during PSV or S/T. Pt comfort is goal
Ramp
More often found on machines used in the chronic care setting, ramp allows the positive pressure to increase gradually over a set delay-time control.
Alarms
Although not nearly as comprehensive as the alarm settings found on critical care ventilators, many NIV machines have the following alarms to increase patient safety: High- and low-pressure values Disconnect Machine failure Excessive leak Apnea alarms
AVAPS
Average volume-assisted pressure support.
- Helps pts maintain a Vt equivalent to or greater than a target Vt through the automatic manipulation of PS
- Machine averages Vt over time and gradually adjusts IPAP as needed
AVAPS: if pt effort decreases,
IPAP is increased
and if pt effort increases, the IPAP is decreased
Adapt SV
uses an internal algorithm to improve synchrony between the levels of PS and the pts breathing. It monitors the pts average RR and the direction/ magnitude/ rate of change of the pts airflow
-Adapt SV then uses a BUR to mirror the pts breathing in the even of apnea or hypopnea.
Several different responses should be evaluated
Physiologic: ABG, Pulse ox
Objective: RR, Hemodynamic impact
Subjective: dyspnea, comfort, neurologic status
Positive pressure ventilators- potential adverse effects
Barotrauma and hemodynamics
-Unique to NIV is the potential for gastric insufflation and skin breakdown associated with the interface
Failure of NIV may be evidence by
- Decreased mental status
- RR greater than 35
- Worsening resp acidosis
- Inability to maintain a SpO2 greater than 90%
- Intolerance
- Inability to manage secretions
NIV
Negative pressure Ventilators- another form of NIV that use an external device, sometimes referred to as a body ventilator, to generate sub atmospheric pressure around the pts chest and abdomen
Examples of NIV
Iron lung Cuirass, or chest shell Pneumosuit Pneumobelt Rocking Bed
In the acute care setting, CPAP can be used to:
Provide lung expansion therapy
Treat hypoxemic respiratory failure
Treat acute cardiogenic pulmonary edema
-In the acute care setting, CPAP can be used to help prevent atelectasis and can improve oxygenation in patients with hypoxemic respiratory failure.
In the chronic care setting (such as the patient’s home), CPAP is most commonly used to treat
OSA-a condition characterized by loss of muscle tone in the neck and throat, resulting in partial or complete airway collapse, apnea, and hypopnea.
-The most common use of CPAP seen in both acute and chronic care settings is to treat OSA.
There is strong evidence that CPAP is a viable treatment option for patients with
cardiogenic pulmonary edema.
-The increase in intrathoracic pulmonary pressure caused by CPAP decreases the work of the heart, improves lung compliance, decreases areas of zero ventilation (shunt), and increases oxygenation.
hypopnea
reduction in airflow associated with lower than normal rates of breathing
Most home CPAP machines can deliver pressures ranging from
3 to 20 cm H2O, with pressure titrated to the level needed to minimize apnea and hypopnea.
The most commonly used CPAP valve is classified as a
threshold resistor-These valves help maintain a constant pressure in the system regardless of flow levels.
-One of the more common examples is the positive end-expiratory (PEEP) valve, which is seen on many bag-mask resuscitators. This valve uses spring tension to produce CPAP.
systems add heat and moisture to the inspired gas, reducing drying of the mucosa and improving patient comfort and compliance.
passover type heated humidity
The nature and degree of airway collapse with OSA can vary as a result of a number of conditions. Factors such as
weight gain, changes in sleeping position/posture, airway congestion, or the use of alcohol or caffeine may all influence the degree of airway collapse.
-In response to this, CPAP machine manufacturers have developed various proprietary modes of automatic pressure adjustment; this is generically referred to as autopositive airway pressure (APAP).
Improvements in the following symptoms may indicate successful CPAP therapy:
Daytime fatigue
Snoring
Poor sleep quality
Morning headaches
How can you evaluate the effectiveness of CPAP therapy in treating OSA?
Repeat a sleep study while the patient is wearing the CPAP machine.
Download compliance data from the CPAP machine.
Ask the patient how she has been feeling
Assess for symptom resolution
