1. Non-Invasive Ventilation

2. Readings
Pages Noninvasive Ventilation, Respiratory Care Equipment, Mosby.
Pages Respironics BiPAP Vision, Respiratory Care Equipment, Mosby.
Pages Essentials of Mechanical Ventilation, Hess.
Two articles on Web CT named: Early Noninvasive Ventilation Averts Extubation & Supplemental.
NIV almost equals Bipap equals Bilevel, but not quite.
How we ventilate is part of Vision module. Are we still using Visions?
4/20/2019

3. Non-Invasive Ventilation
NPPV has been reported in the management of acute respiratory failure
Pneumonia
COPD exacerbation
CHF
Asthma (very little data to support)
Obstructive sleep apnea
Other...
Change for next year.
Other reasons-failure post-extubation.
Big uses – COPD and CHF, early intervention in ERs shown to decrease chance of intubation, decrease days in hospital, etc.
4/20/2019

4. Nosocomial Infection
Major source of morbidity and mortality in critically ill patients
Use of invasive devices increases risk for developing nosocomial infection
Endotracheal tubes leading factor
Secondary factors include intravenous catheters, urinary catheters
One of the big reasons for use of Bipap.
4/20/2019

5. Reduction of Nosocomial Pneumonia
NPPV maintains natural barriers provided by glottis, upper respiratory tract
May decrease duration of mechanical ventilation, need for sedation, and length of stay (LOS) in ICU
Reduces mortality in select groups of patients with COPD exacerbation
Upper a/w acts as a filter – Limits lower a/w infection, gives ability to swallow, gag, and cough.
4/20/2019

6. NPPV and Hospital Acquired Pneumonia
Matched case control study
50 pts acute COPD or cardiogenic pulmonary edema received NPPV
50 matched controls received invasive ventilation
Why does UTI increase in ventilated population?
4/20/2019
Girou et al, JAMA 2000; 248:

7. Also look at oxygenation. Might be more important then CO2
Also look at oxygenation. Might be more important then CO2. CO2 is WOB, O2 a matter of atelectasis, diffusion gradients. Never like looking at fixed parameters.
4/20/2019

8. Clinical Application of NPPV
Step one
Is the patient sick enough?
Step two
Is the patient too sick?
Respiratory arrest
Medically unstable
Unable to protect airway
Uncooperative
What parameters need to be looked at for the patient to be sick enough for Bipap? The main one is WOB above all else. Clinical examination! Then RR, PaO2, and PaCO2
The big, big one is that the patient must be able to protect upper a/w, so LOC/GCS is very important! If the patient is not awake, don’t put them on it!
Only exception being for palliative care reasons.
4/20/2019

9. Patient Selection for NPPV
Respiratory distress with dyspnea, use of accessory muscles, abdominal paradox
pH < 7.35 with PaCO2 > 45 mmHg (acute hypercapnia)
Respiratory rate > 25/min (tachypnea)
Acute hypoxemic respiratory failure
Numbers not as important as presentation. I’m not a number guy; some of your Dr’s will be.
4/20/2019

10. Exclusions for NPPV Airway protection Unable to fit mask
Uncooperative patient – Anxiety, unable to cooperate
Uncontrolled dysrhythmias and/or evidence of MI
Upper airway obstruction or facial trauma, burns, facial surgery
Placing a mask over your face increases anxiety; it takes a while before it is considered more comfortable; it must greatly decrease WOB before pt likes it. They will be more uncooperative with it on; it may lead to panic.
Good coaching is essential.
So why would you be unable to fit mask? Beard, alternate facial structure, no dentures in. Should you keep dentures in?
4/20/2019

11. Exclusions cont. Apnea or need for rapid intubation
Unstable hemodynamics – BP< 90mmHg
High aspiration risk, unable to protect airway, copious secretions
Anatomic lesion of upper airway
Relative contraindications
Asthma
Pneumonia
Don’t bipap for secretion-related issues – Dries up secretions, pushes them down and prevents clearing. May improve short-term oxygenation, but pt usually deteriorates and is much more difficult to treat when they get intubated.
4/20/2019

12. Evidence for Effectiveness
Initial response may predict success or failure
Those who failed were intubated within first 12 hours
Success associated with a rapid decrease in PaCO2
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13. COPD – Evidence
275 patients screened; 75 enrolled NPPV Control Intubation Rate 26% 74% Complications 16% 48% Hospital Stay 23 days 35 days Mortality 9% 29%
4/20/2019
Brochard et al, N Engl J Med 1995; 333:

14. Candidates for NPPV Sick, but not too sick
COPD, CHF, and perhaps others
Short-term requirement for ventilatory support
These are the patients that it is most successful on, mainly.
4/20/2019

15. Weaning COPD Patients
After 48 hrs, patients randomized to PSV by ETT or extubated to NPPV by mask
NPPV group had reduced weaning time, fewer ICU days, lower nosocomial pneumonia rate, improved 60-day survival
Nava et al, Ann Intern Med 1998; 128:
4/20/2019

16. Nasal Masks
4/20/2019

17. Oronasal (Full-Face) Masks
4/20/2019

18. Nasal Pillows
Frequently now used in home CPAP machines.
4/20/2019

19. Common Problems with Interface
Headgear too tight (Should be able to easily fit 2 fingers between headgear and pt head)
Chin strap may help with oral leaks when using nasal masks
Mask too large (*Most common problem)
Full-face
Bottom of mask should fit under bottom lip
Top of mask should lie at the junction of nasal bone and frontal bone, fitted to cover (but not occlude) nares snuggly
Sizes don’t fit that well; much work involved in getting them to fit. Don’t just make it tighter and tighter.
4/20/2019

20. Ventilators vs. Stand-Alone Units
Most newer-generation ventilators have both invasive and non-invasive capabilities
The fundamental difference between invasive and NIV is the ability to compensate for leaks
What modes would we be using?
There are also multiple stand-alone NIV machines on the market
Fundamental difference is the use of single-limb circuits on NIV units
NIV machines work on same principles as the OSA machines we see so often.
So what changes when we only use one limb compared to two limbs?
So flow goes in only one direction.
How does pt exhale? Must be through a leak in the system as there is no exhalation valve back at the ventilator.
How does machine maintain pressure? By varying level of flow; it must have a continual leak.
What type of breath do I deliver? It has to be a pressure breath, so you have 2 levels of pressure: low and high.
How does it trigger and sense an effort? It goes back to continual leak and the flow needed to maintain pressure; if pressure drops, you need more flow to maintain it – This is how it senses an effort, by a change in flow. This creates problems, as a change in leak will affect the ability to trigger.
How does it measure a delivered breath? It doesn’t have an expiratory limb with an expiratory flow sensor to measure an exhaled breath. So is an estimation based on the flow delivered minus the estimated leak? It’s very inaccurate and dependent on the mask seal.
4/20/2019

21. NIV – Modes and Breath types
Three main modes that can be used
CPAP
Bilevel
PAV
Note that these are all pressure breaths. Why?
Proportional-Assist Ventilation
CPAP (What is the difference between CPAP and PEEP?) – For specific uses: When no support is needed. For recruiting alveoli (reversing atelectasis), changing the gradient to improve oxygenation, redistributing fluid in pulm edema. There is one continual pressure; the vent changes flow to keep pressure constant, so more flow is delivered when pt is making an effort.
Bilevel – Relates to PSV to levels of pressure, a low and high. Called IPAP and EPAP: When vent senses a breath it cycles from low to high pressure and vice versa. The triggering ability is based on changes in flow which is subject to failure.
PAV we will talk about more later.
These are all supportive modes. Much discussion in the past about the use of NIV with rates to ventilate patients. Massive problems with this. Can’t force air in non-invasively and know where it is going to go – You don’t know what the glottis is doing, just as likely to ventilate the stomach as the trachea, or ventilate a leak. Very high aspiration risk. Regardless of what you may read in the texts I can’t recommend it. Dysynchrony is a major concern with Bipap, if delivering a breath during exhalation you have discomfort, increase WOB and inflation of the stomach.
4/20/2019

22. Humidification Is necessary for patient comfort and safety
Perhaps even more than invasive
Must be used if ventilating for any prolonged period of time
Be certain that humidifier does not interfere with operation of ventilator
Use only humidifiers recommended by the manufacturer
Must humidify if using for any length of time!
4/20/2019

23. Other Considerations Rebreathing of CO2
If flow through mask not high enough
Oxygen concentration
Depends on where oxygen is introduced into the machine
Medication delivery
MDI or SVN can be added in-line
How much drug is delivered to patient?
CO2 more of a concern in older models – Increase EPAP level to increase flow and washout of mask, or increase leak in/around mask.
Changing O2 concentrations depending on the type of unit being used: Newer models can be hooked up to a high-pressure source and can precisely titrate the oxygen levels the machine delivers. For older or home-use models (OSA), you must Tee in oxygen, so O2 concentration will vary t/o breath cycle or if a leak changes.
Delivery of medication is questionable through the machine, as the flows are very high to maintain PEEP, so you have large losses of drug compared to invasive delivery. So either give more drug (but how much?), or take pt off to give them drugs.
4/20/2019

24. Practical Application
Choose a ventilator capable of meeting patient needs
Choose the correct interface; avoid mask that is too large
Explain therapy to the patient
Silence alarms and choose low settings
Initiate NPPV while holding mask in place
Secure mask, avoiding a tight fit
4/20/2019

25. Practical Application
Titrate both pressures to patient comfort
Titrate FiO2 to SpO2 > 90%
Avoid PIP > 20 cmH20
Titrate PEEP to SpO2 based on reason for initiation of therapy
Continue to coach and reassure patient; make adjustments to improve patient compliance
4/20/2019

26. Strategy for Acute on Chronic Respiratory Failure
Maximum conventional therapy
Nasal mask ventilation
Face mask ventilation
Some rewrites needed
Endotracheal Intubation and IPPV
Wean conventionally
Extubate and wean using NPPV/face mask
4/20/2019

27. Complications Leaks Mask discomfort and facial soreness, necrosis
Eye irritation
Sinus congestion
Oronasal or airway drying
Patient-ventilator dyssynchrony
Gastric insufflation
Hemodynamic compromise
Acute MI??????????????
4/20/2019

28. Monitoring the Effect Response to NPPV
Physiologic – ABG, oximetry
Objective – Respiratory rate, hemodynamics
Subjective – Dyspnea, comfort, neurologic status
Mask – Fit, comfort, leak, skin breakdown
Respiratory muscle unloading – Accessory muscle use, paradoxical movement
Abdomen – Gastric distension
4/20/2019

29. Chronic Applications
Restrictive lung disease (Chest wall deformity, post-polio, ALS, muscular dystrophy, MS)
Symptoms – Fatigue, dyspnea, morning headache
PaCO2 > 45 mmHg
Nocturnal oximetry with SpO2 < 88% for 5 consecutive minutes
For progressive neuromuscular disease, Pimax < 60 cmH20 or FVC < 50% predicted
COPD
PaCO2 > 55 mmHg
Look into more
4/20/2019

30. Chronic Applications
AADL funding for BiPAP difficult without full polysomnographic testing
Wait list over 2 years
Must show reduction in PaCO2
AADL funding for CPAP requires Level Two Sleep Lab testing
Long waiting list for evaluation
If BiPAP indicated, must still wait for polysomnographic testing
Review! Look into more
4/20/2019

31. Summary
NPPV associated with a lower intubation rate and lower mortality in selected patients with acute respiratory failure, particularly COPD
Clinician skill may be more important than the technical aspects
Patient comfort may be the most important effect of NPPV to monitor
What are the predictors of success?
4/20/2019