Question Answer
Noninvasive Positive Pressure Ventilation The application of positive pressure via the upper respiratory tract for the purpose of augmenting alveolar ventilation Typically administered through a nasal or oral mask Increasingly popular due to newer vents & patient interfaces
Goals of Noninvasive Ventilation (Acute Care) Avoid intubation Relieve symptoms Improve gas exchange Improve patient/vent. Synchrony Maximize patient comfort Decrease length of stay
Indications of NPPV Acute Care COPD Asthma Acute cardiogenic pulmonary edema Community acquired pneumonia Hypoxemic respiratory failure Immunocompromised state Do not intubate oreders Postoperative status Difficult weaning
Goals of Noninvasive Ventilation (Chronic care) Improve symptoms Enhance QOL Increase survival Improve mobility
Indications of NPPV Chronic Care Restrictive thoracic disease COPD Nocturnal hypoventilation
COPD Studies have shown a reduction in the need for intubation of patients with acute exacerbations Reduction in in-hospital mortality Reduced length of stay NIPPV is an acceptable alternative to intubation in patients with acute exacerbation of COPD
Asthma The Meduri study reported positive results in the care of 17 patients with status asthmaticus Previous authors studied suggested NIPPV was not indicated for status asthmaticus
Acute Cardiogenic Pulmonary Edema (a restrictive disorder) A CPAP of 10 to 12.5 cm H20 should be considered before NPPV is used in the care of patients with acute pulmonary edema Caused by increased pulmonary capillary hydrostatic pressure pushing fluid into the interstitial space and alveoli.
Community Acquired Pneumonias Found to be useful in only those patients with underlying COPD Current recommendations are to use NPPV on patients with community-acquired pneumonias only on patients with COPD
Hypoxemic Respiratory Failure Defined by PaO2/FiO2 ratio of less than 200 Studies have shown some success while others show no benefit to reduce intubations, LOS, and mortality Conflicting reports limit clinical recommendations at this time
Other Indications Providing support for do-not –intubate patients Postoperative patients Difficult weans Lower nosocomial infections Use recommended for pts with mod to severe distress and immunocompromised diseases
Do Not Intubate NPPV in care of do not intubate patients with irreversible disease is controversial Does offer some relief of symptoms Current recommendations is that the use of NPPV with do not intubate patients is justified if pt. Disease is reversible
Post Operative Patient’s After lung resection increased PaO2 without air leaks or increasing deadspace Prophylactic use after gastric bypass improved SpO2 and FVC Outcome potential looks promising
Difficult Weaning Patients NPPV reduces weaning time, length of stay, incidence of VAP, and 60 day mortality Studies supported NPPV in weaning of COPD patients but cautioned in pt selection Pt. Must be cooperative, maintain airway, and clear secretions
Reintubations Patients who are difficult to reintubate should not be extubated early to receive NPPV COPD patients who’s extubation failed. had improved gas exchange and reduced need for reintubation
Extubations Patients who may benefit from NPPV after extubation include: COPD Acute Pulmonary Edema Post Extubation Stridor
Restrictive Thoracic Diseases Includes Neuromuscular diseases, spinal cord injuries, kyphoscoliosis. Provides rest to respiratory muscles Lowers PaCO2 Improves lung compliance, volume, and deadspace Pts should have symptoms of nocturnal hypoventilation before NPPV is considered
Long-Term care of COPD The current recommendation is to use NPPV with pt.s having severe COPD when they exhibit Nocturnal hypoventilation PaCO2 of 55 mm Hg or greater or PaCO2 between 50 and 54 with nocturnal desaturations
NPPV Criteria for Acute Respiratory Failure Use of accessory muscles Paradoxical breathing RR > 25 b/m Dyspnea PaCO2 > 45 mmHg with pH < 7.35 PaO2/FiO2 ratio< 200
Exclusion Criteria for NPPV Apnea Cardiac instability Uncooperative Facial burns Facial trauma Aspiration concerns Secretions
Predictors of Success in Acute Care Setting Minimal air leak Low severity of illness PaCO2 > 45 mm Hg but < 92 mm Hg pH < 7.35 but > 7.22 Improvement within 30 minutes-2 hrs Improve RR and HR
Noninvasive Ventilators Electrically powered, blower driven, and microprocessor controlled Single circuit design for constant flow Small leak is required Trigger must tolerate leak in system
Noninvasive Ventilators Capabilities Provide rates to 30 b/m Pressures to 30 cm H20 EPAP to 15 cm H20 Flows of 60 l/m at 20 cm H20 pressure FiO2 to 50% Minimal re-breathing potential
Initial settings NPPV Ventilator Appropriate sized interface Patient seated at 30 degree angle IPAP of 8 to 12 cm H20 EPAP of 3 to 5 cm H20 Back up rate
Noninvasive Ventilators Alarms Circuit disconnect Loss of power Battery failure
Initial Setting Critical Care Ventilator PSV with 5 to 8 cm H20 PEEP 0 to 5 cm H20 Flow triggering at 2 to 5 l/m
Initial Setting Critical Care Ventilator A/C Mode VT of 10 ml/kg Flow of 60 l/m F of 10 b/m PEEP of 0 to 5 cm H20 Flow triggering between 2 and 5 l/m
Initiations of NPPV Encourage patient to hold the mask in place while head gear is applied After pt is comfortable with initial settings, increase the inspiratory pressures or Vt until 5 to 7 ml/kg is obtained Check for leaks/adj. strap tension
Complications of NPPV Mask Related Discomfort Skin erythema Claustrophobia Nasal bridge ulceration Rash
Complications of NPPV Flow/Pressure Related Nasal congestion Sinus or ear pain Nasal or oral dryness Eye irritation Gastric insufflation
Major Complications of NPPV Aspiration Pneumonia Hypotension Pneumothorax
Air Leaks Mask fit essential Use of ExpSen% and RiseTime % to improve ventilator/pt synchrony 
Question Answer
vents can measure what? presure, vol., flow or time
conditional variable is used for what? used by vent control circuit to make decisions. Ex: if value of a cond. variable reaches preset level, then some action occurs to change vent pattern.
how is acute cardiogenic pulmonary edema managed if hypercarbia is present? NPPV noninvasive positive pressure ventilation
What is NPPV used for in hypoxemic respiratory failure? it is used if pt with poor outcome from intubation
when do intubate a pt with ALI/ARDS? if no improvement within 1 to 2 hours
how do you manage acute cardiogenic pulmonary edema? CPAP of 8 to 12 cm H2O with 100% O2
What are the weaning modes CPAP, SIMV, IMV, SMV
What control do you use with a head injury? volume control
peep is used for what? presure at the elvated level at expiration
what will peep help with? increased PaO2, increased FRC, improves o2
motion equation p=(elastance x vol) + resistance x flow)
ventilation cycle of breath initiation of inspiration, inspiration its self, end of inspiration, expiration
what are the different ramps? ascending above base and descending below base
trigger variable causing breath to begin
a vent has a preset pressure early in inspiration and holds it for specific time for which inspiration ends. What cycle is it? time cycle
tidal vol is a function of a set ______ and set_________ inspiratory flow and inspiratory time
vol. cycle vent, it provides gas under positive pressure during inspiration till what point? tidal vol needed reaches a preset volume
Breath initiated by the vent mandatory breath
when would you use volume control ventilation RENT Retention (CO2), Even distribution needed, Neuro patient, Trauma to head
combination of mechanical and spontaneous breaths intermittent mandatory breaths
3 variables that vents control vol flow and pressure (remember that vol and flow they always go because of the pressure)
how to figure minute ventilation vt x rr
which variable maintains preset level before inspiration begins? cycle variable
What is preset rate rate set to accomplish desired tidal vol
2 primary drive mechanismes Electric and Pneumatic
sensitivity presure drop to initiate patients breath. higher more effort, lower less effort
when do we use pressure control ventilation Pt. isn’t maintaining oxygenation on own, ARDS, Restrictive diseases, refractory hypoxemia
setting range for pressure trigger .5 to 1.5 cmH2O
setting range for flow trigger 1 to 3 L/min
vent device does not directly control the delivered vol. flow control
during volume targeted ventilation what determines total cycle time? rate
what variables will help determine expiratory time? flow volume rate
what parameter serves as baseline of all ventilators? presure
what baseline variable is used on all modern ventilators? PEEP
What are the variables a vent can control? flow volume pressure
ventilator used to transport? punmatic battery fluid logic
with neuro muscular disorder which setting do I use? volume control
cause a breath to end? cycle variable
highest peak inspiratory presure ascending wave
flow control variable constant? varies? flow and volume constant, pressure varies
what control is used for restrictive disease? presure control (is restrictive so we need pressure to get O2 into lungs)


Egan’s Chapter 42 Practice Questions:

1. Close Loop Control: Control circuit that receives feedback from a measured variable that automatically adjusts a gas delivery variable based on the feedback

2. Compliance: Volume change per unit in applied pressure

3. Control Variable: Primary variable that the ventilator controls to provide inspiration: Pressure, Volume Time, or Flow

4. Cycle Variable: Variable that terminates inspiration during mechanical ventilation

5. Dual Control: Mode of ventilation in which the control variable (pressure, volume, or flow) switches during a breath

6. Elastance: Tendency of matter to resist a stretching force and recoil or return to its original size or form after deformation or expansion; the reciprocal of compliance. Also called elasticity.

7. Open Loop Control: System in which there is no control over the delivered variable

8. Phase Variable: Signal that is measured and used by the ventilator to begin some part (phase) of the breathing cycle

9. Resistance: Impedance to flow in a tube or conduit; quantified as ratio of the difference in pressure between two points

10. Target Variable: Variable that can be reached and maintained at a preset level before inspiration ends but does not terminate inspiration.

11. Time Constant: Mathematical expression describing the relative efficacy of lung unit filling and emptying and computed as the product of compliance times resistance (measured in seconds)



12. Trigger Variable: Variable that initiates inspiration during mechanical ventilation