So, they wanted to talk to us about VPAP. Their goal was to sell VPAP units. They kept talking over each other so you could see their excitement. VPAP units work. Studies show they prevent readmissions for COPD, so they said.

They said it's easy to qualify patients for VPAP. All they have to do is have one blood gas with a PaCO2 greater than 50. It doesn't matter when that ABG was done. It could have even been done in the ER when the patient was having a flare-up. 

One of the reps said that it's easy setting patients up on VPAP. All we had to do was notify them that a patient qualifies. Then they take over from there. They said that they talk to the doctor. They said that they talk to the patient. And then they set the patient us. 

One of the reps is the one who works with the patients. He said that he has been doing this for two years, and only had one patient reject the machine. He said they are tolerated that much. 

They made VPAP sound so good. They made it sound way better than BiPAP. And, as a bonus, it's hard to qualify a patient for home BiPAP from a hospital admission. 

So many times we have had people on BiPAP. They had high PaCO2 levels at one point. But when it came time to discharge the patient, we were unable to qualify them for home BiPAP. So, not getting the BiPAP that they needed at night, they ended up being readmitted within a week or two. 

So, the idea that VPAP works just as well as BiPAP. The idea that it is well tolerated. The idea that it's easy to set patients up with them for home use, was well accepted by the folks at the RT Cave. 

My question is: is this too good to be true. Are we too quick to accept this? After all, these reps aim to make money off this. They are making money by getting Medicare to pay for VPAP machines. And, I've been told that it's these types of people who funded all the research. So, is the research tainted? These are questions I aim to investigate. 

Anyway, I do see good about VPAP. I have seen a few patients using them who tolerated them well. But I'm still curious what the studies show. 

BiPAP and CPAP: Answering all your questions

Your question: How high can you set CPAP? What are the disadvantages of CPAP that is too high?

My answer. This is a good question. According to Egans, CPAP is a continuous flow of pressure on inspiration and expiration.If there are alveoli that are collapsed due to atelectasis, CPAP acts to recruit them, and open them up. It thereby acts as a splint to keep them open to improve oxygenation. If CPAP levels are set too high, alveoli will be over-distended, and this may result in air trapping. (1, page 1066)

Another thing to keep in mind here is that CPAP acts to reduce venous return to the heart so the heart doesn't have to work so hard to pump blood through the body. This is the advantage of using CPAP to treat heart failure. If CPAP is set too high, this pressure may ultimately reduce venous return enough as to cause a reduction in cardiac output, which can be measured by a drop in blood pressure.

Over-distended alveoli and air trapping can also result in a drop in oxygen levels, and this can be measured by oxygen saturation monitor.

Your Question. How high can you set IPAP on a BiPAP machine?

My answer. The best answer I can give to this question is a theory, as is much of the medical profession. From what I have read (and you can help me find a source here) is that a pressure support or IPAP higher than 20 in a non-intubated patient may act to obstruct, or block, the esophagus. This can prevent the patient from swallowing. You can exceed a pressure of 20 if you absolutely must to improve oxygenation or ventilation. However, if you must do this, talk to the doctor about ordering a nasal gastric tube (NG). 

While it's generally not a good idea to exceed the recommended settings, I have from time to time had doctors insist I do this. I just make sure to remind the physician that there is a down side to too much pressure.

Your question.  Is it true that you need an IPAP greater than 10 to be therapeutic?

My answer. The goal of IPAP is to assist with inhalation to reduce work of breathing and improve ventilation. If an IPAP of 10 results in an ideal tidal volume for that patient, then an IPAP of 10 will be fine. Some patients have small frames, in which case an IPAP of 10 (or less) may provide adequate support. Keep in mind here that some people with COPD do not have enough lung function, especially during flare-ups, to adequately blow off CO2. For these patients, just assisting them get to their normal, ideal tidal volumes will be all that is needed. So, you do not necessarily have to blast patients with the highest pressure support. If you are getting adequate tidal volumes (using your usual formula of 6- ml/kg ideal body weight), then you are probably fine.

Your question. Is it true you can't set a rate on BiPAP?

My answer. Part of the advantage of BiPAP, is if the machines senses that a patient hasn't taken a breath, it can force the patient to take a breath. This is ideal for preventing sleep apnea. So, ideally, you should set the BiPAP rate at around 6-8. Usually patients will breathe over this set rate. However, if they don't, then the machine will assure at least a minimum respiratory rate.

Your question. How are CPAP and BiPAP set? What are the ideal settings to use?

My answer. The ideal settings should be determined by doing a sleep study. A sleep study technician will titrate settings until the best settings are determined. You will want the lowest setting necessary to keep airways open and maintain adequate oxygenation. Of course, you don't want too high to prevent drops in blood pressure and oxygenation as noted above. There are also newer machines that are auto-titrating.

Your question. When you are setting up a patient on BiPAP in the clinical setting, what are good start settings?

My answer. This is open to debate. It is also open to varying opinions. The general consensus where I work is ideal start-up settings are IPAP 10 and EPAP 4. Settings can be adjusted until an ideal tital volume and oxygenation status is determined.

Your question. How big of a gap between IPAP and EPAP do you need.

My answer. The answer here is another one that is open to personal opinion. The general consensus where I work is that you would like to keep the gap at a minimum of 5. For example, you will want to set the IPAP at least 5 over EPAP. Keep in mind, however, the ventilator that you are using.

Your question. How is Pressure Support (PS) measured on BiPAP. It depends on the machine you are using. On the V60, it is measured over PEEP. So, if you are using a V60 ventilator, and you have the IPAP set at 10 and the EPAP set at 5, you are essentially using a Pressure Support of 10 and a CPAP of 5. On the other hand, if you are using a machine that does not measure PS over PEEP, and you use settings of 10/4, then the measured PS is 5. So, this is why it's important to know your machine.

Your question. Is it true that if a patient requires BiPAP post extubation that the patient never should have been extubated and should be re-intubated?

My answer. Actually, this subject has been extensively studied, and the results are relatively inconclusive. However, some studies show that BiPAP post extubation may prove useful in some patients, especially those with end stage COPD where airway protection and pulmonary toilet is not a concern. This may occur when patients are incorrectly assessed for readiness to wean, or when patients self extubate. It may also occur in some patients, such as those with end stage COPD who are anticipated to still need some support although you don't want to risk further complications of intubation, and a trial of post-extubation BiPAP is done on purpose. Some studies do show this may prove beneficial. However, it should also be noted that the patients described here have a 40% mortality rate.  (5)

Your Question. Does BiPAP really help with heart failure? Doctors say it pushes fluid out of the lungs.

My answer. Both CPAP and BiPAP, by providing increased intrathoracic pressure, have been shown to reduce both cardiac preload and afterload, which reduces the amount of work the heart has to do. Some physicians think it works by pushing fluid out of interstitial spaces, and this is why it works. However, while this does occur to a small extent, it's not enough to have a therapeutic benefit. (5)


Your Question. Does BiPAP truly benefit people with COPD.

My answer. Yes. Studies seem to show that IPAP reduces airway resistance due to bronchospasm and secretions to make it easier to take in a breath and reduce dyspnea The machines can also sense when a patient has not taken a breath to force them to take a breath, thereby preventing apnea. EPAP also acts to splint the upper and lower airways to keep them open at end expiration. This prevents soft tissues in the upper airway from collapsing and causing apnea, and it also recruits collapsed alveoli and keeps them open to improve oxygenation. Various studies have shown that BiPAP used to treat episodes of severe COPD, whether caused by COPD or heart failure, in the hospital setting greatly improves outcomes and hospital length of stays, and reduced hospital costs. Part of this is because BiPAP often prevents the need for invasive intubation and mechanical ventilation. Nocturnal BiPAP used every day at home for a minimum of four hours per day significantly reduces COPD flare-ups and makes them less-severe when they do occur. This has made it so that people living with COPD can live long lives with quality. (1, 4, 6)

References:

1. Kacmarek, Robert M., James K. Stoller, Albert J. Heuer, “Egan’s Fundamentals of Respiratory Care,” 10th edition, 2013, Elsevier Mosby, pages 1066, 1134-5
2. “Non-Invasive Ventilation in COPD Exacerbations,” Nursing Times, September 3, 2013, https://www.nursingtimes.net/clinical-archive/respiratory/non-invasive-ventilation-in-copd-exacerbations/5062992.article
3. Criner, Gerard J., Rodger E. Barnette, Gilbert E. D’Alonzo, editors, “Critical Care Study Guide: Text and Review,” 2nd edition, 2010, Springer
4. Respiratory Therapy Magazine: Noninvasive BiPAP Systems May Help COPD Patients, January 28, 2015, http://www.rtmagazine.com/2015/01/noninvasive-bipap-systems-may-help-copd-patients/, accessed 3/31/17
5. Maclntyre, Neil R., “Mechanical Ventilation: Noninvasive Strategies in the Acute Care Setting,” Medscape, http://www.medscape.org/viewarticle/450209, accessed 3/31/17
6. Ankjærgaard, Kasper Linde , et al., "Home Non Invasive Ventilation (NIV) treatment for COPD patients with a history of NIV-treated exacerbation a randomized, controlled, multi-center study," BMC Pulmonary Medicine, 2016, http://bmcpulmmed.biomedcentral.com/articles/10.1186/s12890-016-0184-6, accessed 4/1/17
7. Respiratory Therapy Magazine: Nocturnal BiLevel Ventilation for the COPD patient," February 7, 2007 http://www.rtmagazine.com/2007/02/nocturnal-bilevel-ventilation-for-the-copd-patient/, accessed 4/1/17
8. Lainscak, Mitja, Stefan D. Anker, "Heart failure, chronic obstructive pulmonary disease, and asthma: numbers, facts, and challenges," ESC Heart Failure, volume 2, issue 3, 2015, pages 103-107, http://onlinelibrary.wiley.com/doi/10.1002/ehf2.12055/pdf, accessed 4/2/17

Patient Education: CPAP -vs- BiPAP

The following was originally published at healthcentral.com/copd on April 17, 2015.

CPAP -vs- BiPAP: What You Need To Know

Some people with COPD, or COPD plus sleep apnea, may benefit from CPAP or BiPAP. So what are these, and how might they benefit you?

Ventilation. Your lungs make sure you are taking in enough oxygen and blowing off carbon dioxide. Oxygen is an essential element in the air that your cells need to make energy. Carbon dioxide (CO2) is a waste product made by cells. An inhalation of an adequate depth is required for adequate ventilation to occur.

Diseases like COPD and Sleep Apnea may compromise ventilation, making it so you are not taking in enough oxygen and/ or blowing off enough CO2.

COPD. The disease process increases resistance in your airways, forcing you to work hard to take in a breath. This causes shallow breathing, causing areas inside your lungs that do not stay patent, a medical term for open. Less ventilation occurs, causing your oxygen levels to fall and your CO2 levels to rise.

Sleep Apnea. Soft upper airway tissue may collapse while you are sleeping, causing you to stop breathing for ten seconds to a minute. You may have up to 30 such episodes during a typical night. During these episodes you are not inhaling oxygen, causing your oxygen levels to drop. You are also not blowing off CO2, causing your CO2 levels to rise. This can make daytime living difficult, and may even increase your risk of dying while you are sleeping.

So, what are CPAP and BiPAP, and how might they help? They are non-invasive machines that supply a pressure to keep your airway patent and to assist you with your breathing.

CPAP. This is an acronym for Continuous Positive Airway Pressure. A continuous flow of pressure is applied during inspiration and expiration. It keeps your alveoli patent to assure adequate oxygenation. It keeps your upper airway patent to prevent apnea.

BiPAP. This is an acronym for Bi-Level Positive Airway Pressure. It provides a combination of IPAP and EPAP.

1. IPAP. This is Inspiratory Positive Airway Pressure. It is a pressure during inspiration that assists your inhalation (makes it easier to inhale). It makes sure you are ventilating, or taking a deep enough breath to blow off CO2. It also makes breathing easier by allowing you to rest your respiratory muscles.
2. EPAP. This is Expiratory Positive Airway Pressure. It is the same thing as CPAP, only it’s called EPAP when used with a BiPAP machine. It simply makes sure your airways stay patent so the next breath comes easier.

Sleep study. This is necessary to determine if you need CPAP or BiPAP. You will be hooked up to a variety of monitors, and a sleep technician will monitor you while you are sleeping. If you have apnea episodes, or if your oxygen levels drop, the technician will determine what pressures are ideal for you.

Home. Your doctor may determine you need CPAP or BiPAP at home. These are set up by home health care providers for you to wear every night. They fit nicely on a nightstand, and are usually very quiet and comfortable.

Hospital. When you are having a COPD flare-up, a doctor may prescribe CPAP or BiPAP to help you breathe better. These are used short term to buy time for other therapies ordered by your doctor to start working, such as bronchodilators, corticosteroids, antibiotics, and diuretics.

These are usually set up and managed by a respiratory therapist like myself.

Masks. There are a whole assortment of nasal pillows, nasal masks, face masks, and full face masks for you to try. Your home health provider will help you find which one that works best for you.

Compliance. Most people find that the benefits of using these machines -- such as improved quality of life -- make them very easy to get used to. Of course it helps that modern machines and masks are made with your comfort in mind. So if your physician recommends you try CPAP or BiPAP, please give it a try. You may find that it greatly improves your quality of life.

Further Reading.

• Your Journey Down the Respiratory Tract
• The Link Between COPD and Sleep Disorders
• My interview with Roxlyn Cole, a COPD patient using BiPAP
• Asthma and COPD: Basic Mechanisms and Clinical Management, page 842
• CPAP -vs- BiPAP: What RTs Need to Know

Can you set a rate on a BiPAP

 Your Question.  Where I work, we have a doctor who insists on having the backup rate set at 16-20 on patients with high CO2s.  I tried to explain to him that we cannot do this on a BiPAP. Am I right.

My Answer.  You are right.  BiPAP provides a breath to the patient when a certain flow is sensed. If the patient is breathing at a rate of 10, and you put in a rate of 16, the machine is going to continue to try to force in a breath while the patient is exhaling.  All this is going to do is create asynchrony between the machine and patient.  It will create little blips on the waveform that do not result in breaths.  The BiPAP is going to constantly alarm while this is occurring anyway, so you won't be able to do it for long without irritating the patient, nurses, and probably even yourself.

 On the contrary, you can set the backup rate to less than the patient's current rate.  For instance, if the patient has a rate of 16 while he is awake, you can set a backup rate at 8. This way, if the patient is sleeping and has apnea episodes, you can be sure the patient will continue breathing.  This is okay because the patient won't be exhaling against the machine breath.  Obviously you will want the back up rate to be enough to assure adequate ventilation to blow off CO2, although never so high that the BiPAP has a higher rate than the patient's rate when he does start breathing again.  Usually, a back up rate of 6-8 is just fine.  Although, as always, it's important to create settings that are appropriate for a given patient at a given time.

CPAP -vs- BiPAP: What RTs Need to Know

Non-invasive positive pressure ventilation (NIPPV) include machines that allow you to ventilate and oxygenate patients without the need to perform the invasive procedure of intubation. These machines can only be used on a spontaneously breathing patient.

Another acronym commonly used to describe NIPPV is NIV, which essentially stands for Non-Invasive Ventilation. You may actually see other similar acronyms, and they all essentially refer to the same thing.

The two most common forms of NIV are:

1. CPAP 
2. BiPAP 

So, what are they and how might they help your patients?

1. CPAP: This is continuous positive airway pressure. It's a pressure exhale applied during the respiratory cycle that helps keep air passages open so that the next breath comes in easier. Since it keeps the airways patent, it assures adequate oxygenation, and is often prescribed to increase oxygenation.

Indications for CPAP.

• Hypoxemia that is refractory to high concentrations of oxygen by other means. 
• Obstructive Sleep Apnea to prevent the upper airway from collapsing 

Adjusting CPAP settings. CPAP is increased or decreased to maintain a desired SpO2, which is usually greater than 90% SpO2 and 60 PaO2.

BiPAP: This is an acronym for Bi-level (or Biphasic) Positive Airway Pressure. It provides a combination of both IPAP and EPAP.

• IPAP. This is Inspiratory Positive Airway Pressure. It is a pressure during inspiration that assists a patient obtain an adequate tidal volume. Because it provides assistance with inhalation, it therefore decreases the work of breathing required to get air in. Because it assures adequate ventilation, it is often prescribed to blow off carbon dioxide (CO2). 
• EPAP. This is Expiratory Positive Airway Pressure. It is the same thing as CPAP. EPAP is simply used here so you know your talking about CPAP on a BiPAP machine. EPAP is used to improve oxygenation.

Indications for BiPAP.

• Respiratory Failure due to accessory muscles fatigue. It assures adequate ventilation to blow off CO2 and improve oxygenation. 
• COPD to decrease airway resistance, thereby decreasing work of breathing required to take in an adequate tidal volume. By increasing ventilations, it helps to blow off CO2. It also keeps airways patent to improve oxygenation. 
• Pulmonary Edema to help decrease cardiac output which decreases venous return to the right ventricle to reduce blood return to the heart. It also keeps airways patent to help improve oxygenation. It also helps keep alveoli patent to improve oxygenation (prevents alveolar collapse). By keeping alveoli patent, and redistributing alveolar fluid, it helps to reduce pulmonary compliance and reduce work of breathing. 
• Atelectasis to help keep airways patent to improve oxygenation 
• Pulmonary Embolis to improve oxygenation 
• Pneumonia to assure adequate ventilations and oxygenation

Adjusting BiPAP settings. As a rule of thumb, the following rules are true.

IPAP. Increase to blow off CO2. It should not be higher than 20 to prevent pressure from blocking the esophagus. By providing adequate tidal volumes it may also help improve oxygenation.

EPAP. Increase to improve oxygenation.

PS. Pressure Support. This is the gap between IPAP and EPAP. The greater the PS is the more CO2 will be blown off.

Patient Leak. It is important to have a small leak to prevent skin breakdown. Most modern machines will compensate for a small leak.

Alarms. Adjusted as appropriate for each patient.

Contraindications for BiPAP include.

• Inability of patient to protect own airway (decreased level of consciousness). This includes the inability of the patient to pull off the mask if it becomes full of fluid, such as vomit or spit. 
• Increased secretions (i.e. pulmonary edema, increased sputum production) 
• Any patient at risk of vomiting (post stomach surgery, drug overdose). In this case you may be able to use BiPAP if an NG is inserted. Most machines will compensate just fine for the leak around the tube. 
• Bullous lung disease (emphysema) because the high pressure may cause a pneumothorax 
• Pneumothorax may be complication due to increased pressure;;may blow out rest of good lung 
• Hypotension; High pressures decrease cardiac output 
• Non-compliant patient. Surely you cannot force a patient to use this equipment. 

Study Results. Studies show that the use of NIPPV for respiratory failure in COPD patients results in a greater reduction in CO2 and a normalization of pH, compared to those in the control group who did not use NIPPV. A study also showed those receiving conventional therapy were intubated 67% of the time, while those receiving NIPPV were intubated only 9% of the time. This prevents the complications of mechanical ventilation, particularly the difficulty associated with extubating patients with lung disease.

Studies also show that length of stay in a hospital is reduced among the COPD pupulation using NIPPV. NIPPV may also be used on the medical/ surgical floors, reducing cost. However, those in severe respiratory failure may still require a stay in the critical care unit.

Studies also show that most patients, or about 80%, tolerate NIPPV just fine. (see references #3 and 4 below).

Bottom Line. Non-Invasive Positive Pressure Ventilation machines are ideal for many patients to improve oxygenation and ventilation. They have prevented many critical patients from having to go through the invasive procedure of intubation and mechanical ventilation. They are also useful to assure adequate ventilation and oxygenation in the home setting, especially during the nighttime when breathing seems to be more relaxed.

This post was originally published on 8/4/8 on respiratorytherapycave.blogspot.com; it has been edited for accuracy.

Further Reading.

• Good start settings for BiPAP
• My interview with Roxlyn Cole, A COPD patient who uses BiPAP at night
• Study: Non-Invasive Positive Pressure Ventilation For Acute Respiratory Failure
• Barnes, Peter J., et al, editor, "Asthma and COPD: Basic Mechanisms and Clinical Management," 2nd edition, 2009, page 842 
• Non-Invasive Positive Pressure Ventilation (CPAP or BiPAP NPPV) for Cardiogenic Pulmonary Edema
• 17 Biggest Myths of Respiratory Therapy

Good start settings for BiPAP

Your question: What are good start-up BiPAP settings?

My humble answer: Noninvasive Positive Pressure Ventilation, such as BiPAP, is generally indicated for patients who aren't taking in adequate tidal volumes to blow off CO2, or are poorly oxygenating. It may also be indicated to decrease cardiac output for patients suffering from heart failure to relieve the feeling of dyspnea until other medicines start to work.

A BiPAP is essentially used for the same reasons as a ventilator, only with BiPAP you have a spontaneously breathing patient.  That said, the settings should be adjusted to maintain the desired SpO2, PaCO2 and PaO2.  However, considering the patient is awake and alert, the settings must also be adjusted for patient comfort as well.  

That said, most experts recommend initial start settings as follows:

• IPAP 10
• EPAP 4

These settings supply a low pressures to the patient's airway, and are generally comfortable for the patient. Then they should be adjusted to maintain a desired tidal volume as tolerated by the patient. The tidal volume should be determined by the following formula:

• 5-8cc/kg ideal body weight

If these minimum settings obtain the goal tidal volumes and SpO2, then you are adequately ventilating and oxygenating this patient, and no further increase is needed.  

There are those who will argue with what I just wrote, however.  Many of my peers insist that the settings of 10/4 are non-therapeutic and, once a patient only needs 10/4, BiPAP is no longer indicated.  However, such number watching assumes that every patient is the same.

For example, consider the 98 pound lady who is suffering from a bout of heart failure.  Her lungs are full of fluid, and she is struggling to breathe.  You set up the BiPAP on the basic settings, and her tidal volume is adequate for this patient and her oxygenation improves.  In this case, all that was needed was the basic settings.

For another example, consider the patient with end stage COPD who is having a flare-up and not taking in deep enough breaths to blow off CO2. Or, say this patient isn't even having a flare-up, but when he is very relaxed or is sleeping he doesn't take in an ideal tidal volume.  This patient would benefit from BiPAP even at the lowest setting, if that setting gave just enough boost to maintain an adequate tidal volume to blow off CO2.  

I have seen 10/4 work many times to obtain an adequate SpO2 and tidal volume.  If these settings work, then great.  If they don't, then it's time to increase the settings.  Yet, regardless of what you do, it's important that you do not focus so much on the numbers, but on the patient.  Look at the patient. What does the patient need?

Now, if you're goal is to blow off CO2, then you'll want a larger gap between IPAP and EPAP.  For instance, if 10/4 is not enough to blow off CO2, then increase the IPAP.  If your goal is to oxygenate and a CPAP of four isn't cutting it, then you should increase IPAP and EPAP slightly.

Still, it is a good idea not to exceed 20 of IPAP, as this pressure might block the esophagus, thus preventing the patient from swallowing.  If you need to exceed this pressure, a nasal gastric tube should be in place.  

In my humble opinion, BiPAP should always be ordered "RT to titrate. Then it's up to the RT to use common sense.

This post originally published at respiratorytherapycave.blogspot.com on 4/3/12; it has been edited and updated for accuracy and improved wisdom by Rick Frea

Oxygenating with home BiPAP and CPAP machines

When using a ventilator, either for mechanical ventilation or noninvasive ventilation, a fixed FiO2 is set during ventilatory support. This is the best way of supplying supplemental oxygen to patients, especially because it may be adjusted to maintain a desired saturation.

However, when using a patient's home noninvasive ventilation equipment, either set up for BiPAP or CPAP, oxygen is typically placed directly into the circuit using a constant flow.  When this occurs, the amount of oxygen actually inhaled depends on a variety of factors:

• Oxygen flow
• Leakage
• Circuit
• Interface (face mask, nasal mask, etc.)
• Location of where oxygen is bleed into the system

Studies are still inconclusive as to where the best place to insert the oxygen into the system.  Some therapists place it near the machine, while others place it near the patient interface.  Ideally, the oxygen flow should be adjusted to maintain a desired Spo2.  This may be important for patients who are using their home units in the hospital setting.  

For patients who present in acute respiratory failure, when adequate oxygenation is not obtained with a patient's home unit, a ventilator (which may include a noninvasive ventilation device such as a Vision or V60) should be used in order to deliver a fixed FiO2 that can be easily adjusted to maintain an adequate SpO2.

References:

1. Storre, Jan H, Sophie E. Huttmann, Emelie Ekkernkamp, Stephan Wlterspacher, Claudia Schmoor, Michael Dreher, and Wolfram Windisch, "Oxygen Supplementation in Noninvnasive Home Mechanical Ventilation: The Crucial Roles of CO2 Exhalation Systems and Leakages," Respiratory Care, January, 2014, volume 59, number 1, pages 113-119

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Non-invasive ventilation with humidification: the latest evidence

There continues to be a debate as to the effectiveness of applying humidification to noninvasive ventilation (NIV). Some argue that humidification is not indicated because, regardless of the type of mask used (oronasal, nasal, nasal plugs, face mask), air will be humidified by the patient's natural mechanism.  Yet the crux of the evidence says this is not true, and that supplemental humidification is essential.

The last evidence appears in the January, 2014, issue of Respiratory Care, "Hygrometric properties of inspired gas and oral dryness in patients with acute respiratory failure during noninvasive ventilation."  The authors note the following:

Especially when the NIV ventilator uses unhumidified gas, the upper airway can suffer mucosal dryness and airway dysfunction.  The leak compensation applied by NIV ventilators creates high flow throughout the respiratory cycle, which contributes to loss of heat and moisture. About 40-60% of nasal CPAP users with obstructive sleep apnea report nasal congestion, oral dryness, and throat soreness after breahing dry, cold gases.  

They go on to say:

Lack of humidification during NIV is related to greater mucus viscosity and secretion retention, which increases the risk of upper airway obstruction.  Although there are no general recommendations or guidelines conserning humidification during NIV, humidifying devides are commonly applied when NIV continues for more than 24 hours, if pipeline or cycling gas is in the inspiratory gas, or if the patient frequently experiences difficulty in expelling secretions or reports dryness and discomfort."

The authors note the advantages of adding humidification with NIV is that is that it "adds water vapor to the inspiratory gas during NIV," and this, "ameliorates nasal congestion, and improves satisfaction."

There are presently no guideliness for the use of humidification with NIV, although most hospitals have an unwritten rule to apply it to the unit if a patient requires NIV for greater than 24 hours.  While there is no proven ideal temperature, most experts recommend 31° in the heated humidifier and 34° at the Y-piece.

After performing a study of ICU patients of Tokushima University Hospital to determine the effects of humidification on 16 patients (9 male and 7 female) in acute respiratory failure requiring NIV, the authors concluded:

Clinicians should ensure that proper humidification is supplied when patients complain of oral dryness or when little condensation is observed inside the mask.

Keep in mind here that this is one study with analysis by one group of researchers.  Although other studies have come to similar conclusions.  Consider the following:

1. Holland et all concluded that "NPPV delivers air with a low relative humidity, especially with high inspiratory pressure. Addition of a heated humidifier increases the relative and absolute humidity to levels acceptable for nonintubated patients, with minimal effect on delivered pressure. Consideration should be given to heated humidification during NPPV, especially when airway drying and secretion retention are of concern.
2. Rodriquez et al found that heated humidifiers were more effective than a heat and moisture exhchanger (HME)

So, the evidence is abounding that patients who receive NPPV do benefit from heated humidity.  

References:

1. Oto, Jun, Emiko Nakataki, Nao Okuda, Mutsuo Onodera, Hideaki Imanaka, and Masaji Nishimura, ""Hygrometric properties of inspired gas and oral dryness in patients with acute respiratory failure during noninvasive ventilation." Respiratory Care, January, 2014, volume 59, Number 1, pages 39-45
2. Holland, A.E., L. Denehy, C.A. Buchan, J.W. Wilson, "Efficacy of a heated passover humidifier during noninvasive ventilation: a bench study," Respiratory Care, January, 2007, 52(1), pages 38-44, accessed 5/18/14, http://www.ncbi.nlm.nih.gov/pubmed/17194316
3. Rodrigues, Antonia M., Raffaele Scala, Arie Soroksky, Ahmed BaHammam, Alan de Klerk, Arschang Valipour, Davide Chiumello, Claude Martin, and Anne E. Holland, "
   Clinical review: Humidifiers during non-invasive ventilation - key topics and practical implications," Critical Care, 2011, Volume 16, Issue 1, accessed 4/18/14, http://ccforum.com/content/16/1/203

How does NIV help with CHF?

There have been a few physicians who have explained to me that noninvasive ventilation helps patients with congestive heart failure (CHF), or pulmonary edema, because it forces fluid out of the lungs.  But this is a myth.

The true value of NIV for CHF is best described by Jeffrey Sankoff, MD, from Emergency Physicians: 

Contrary to popular belief, NIMV does NOT push edema fluid out of the lungs. Patients with acute CHF have an imbalance in the CO (cardiac output) of the right and left sides of the heart. With the inciting event (detailed above) the left ventricle becomes compromised but the right ventricle usually does not. So the right ventricle continues to pump forward a normal volume of blood but the left ventricle becomes unable to keep pace. Fluid backs up into the lungs resulting in capillary leak and pulmonary edema. With NIMV, the resultant positive intra-thoracic pressure decreases venous return (blood flowing back to the heart). This reduces right-sided CO to a level that the left heart can equal or even exceed. Fluid ceases to back up and will even begin to be reabsorbed as left ventricular CO improves. Pulmonary edema ceases to worsen and may even diminish, often rapidly.

I think it's essential to understand this, because I have also had physicians place patients on NIV with the hope that it would help with their breathing, but also that it might improve their blood pressure.  The truth is, however, the low blood pressure is a contraindication for NIV, and now you know why.

What are the advantages of NIV?

Sometimes there is confusion regarding the advantages of NIV, otherwise referred to as BiPAP. I have had doctors order it because it "forces fluid out of the lungs" in heart failure, and because it "increases blood pressure." Yet neither of these are actual benefits of NIV. That said, what are the benefits of NIV? The are:

1. IPAP increases ventilation and helps to blow off CO2 
2. CPAP increases FRC and therefore keeps the lungs open so the next breath comes in easier
3. Both IPAP and CPAP help to reduce work of breathing
4. Both the IPAP and CPAP help reduce work of heart

So, how does BiPAP reduce work of heart because the increased intrathoracic pressure decreases preload to the heart, thereby decreasing cardiac output, and thereby decreasing blood pressure.  In this way, it helps to decrease the patients work of heart.  That is how it helps with heart failure.  It does not force fluid out of the lungs. It does not increase blood pressure.

Indications and contraindications for NIV

Noninvasive ventilation (NIV) is commonly ordered, and in many cases allows an opportunity for a patient to recover in lieu of intubation and mechanical ventilation. 

According to the National Institute of Health, the following are the indications:

• Acute respiratory failure 
• Acute or chronic respiratory insufficiency 
• Documented sleep apnea

However nice NIV is, there are times when it is contraindicated.  It is up to the respiratory therapists to remind the attending physicians of these contraindications when they arise.  

Contraindications for NIV are

• Absence of a drive to breathe
• Inability to maintain a patent airway
• Inability to adequately clear secretions 
• Acute sinusitis or otitis media 
• Risk for aspiration of gastric contents 
• Hypotension (NIV may decrease cardiac output, decrease venous return)
• Pre-existing pneumothroax or pneumomediastinum 
• Epistaxis 
• Recent facial, oral or skull surgery or trauma 
• History of allergy or sensitivity to mask materials where the risk from allergic reaction outweighs the benefit of ventilatory assistance 

Benefits of NIV for COPD-CO2 retainers

Citing previous studies, Augusto Savi, et al lists the following as the advantages of using noninvasive ventilation for chronic obstructive pulmonary disease (COPD) patients presenting with respiratory distress. T

1. Increases tidal volume
2. Improves CO2 elimination
3. Reduces respiratory drive
4. Reduction in treatment failure
5. Lower mortality
6. Fewer complications
7. Lower intubation rate

However, they note the following:

In these patients CO2 elimination was increased but overall ventilation-perfusion mismatch is not changed during NIV.  A more important effect is the unloading of the respiratory muslces, which are often close to fatigue in severe episodes of respiratory failure.  

Furthermore, they note the following regarding the safety of oxygenating these patients:

Crossley et al concluded that CO2-retaining COPD patients following a period of mechanical ventilation with PaO2 in the normal range can safely receive supplemental oxygen without retaining CO2 or a depression of respiratory drive.  A new ventilation-perfusjion relationship is established during ventilation to normoxia, and is not altered by further increasing the FiO2.  Nevertheless, the safety of oxygen supplementation during NIV in CO2-retaining COPD patients is not clear.

So it is quite clear that NPPV greatly benefits COPD patients in respiratory distress, and, likewise, there are no harmful effects of oxygenating them as needed to prevent hypoxia.

References:

1. Savi, Augusto, et al, "Influence of FiO2 During Noninvasive Ventilation in Patients with COPD," Respiratory Care, March, 2014, Volume 59, Number 3, pages 383-387

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What are the advantages of BiPAP?

I had a doctor today order BiPAP on a patient who was suffering from heart failure.  I walked into the patient's room and saw that the blood pressure was 65/20.  Based on my knowledge of BiPAP, I felt that it was contraindicated for this patient. 

So I sat down with the doctor.  I said, "The patient has a low blood pressure. Do you still want to use BiPAP." 

He said, "Yes!  He's a very calm patient, and if you irritate him with that mask it may help get his blood pressure up." 

After taking a couple deep breaths, I said, "Can you explain to me what BiPAP does for CHF patients?"

He said, "Yes.  It increases the pressure in the lungs so that it forces fluid out.  It helps decrease the pulmonary edema."

I said, "What I learned about BiPAP is that it decreases preload to the heart, thereby decreasing cardiac output, and thereby decreasing blood pressure.  In this way, it helps to decrease the patients work of heart.  That is how it helps with heart failure.  It does not force fluid out of the lungs."

"Well, put it on him anyway," he said, and stormed out of the room.

That occurred in the emergency room.  Up on the floor, a doctor ordered BiPAP on a patient who was septic, suffering from kidney failure, and in metabolic acidosis.  The patient likewise had a low blood pressure, but it was being somewhat controlled by dopamine. 

I asked the doctor why he was ordering BiPAP.  He said, "Because it will decrease the work of heart.  The patient is a DNR and I understand she's going to crash at some point anyway, but this will help delay the inevitable."

I asked, "So, how do you think the BiPAP will decrease work of heart?"

He answered me:  "Becaues it will force fluid out of the lungs and make it so the heart doesn't have to work as hard to breathe."

I took a deep breath, and said, "BiPAP will decrease the work of heart, but it does it by decreasing preload. This in turn decreases after load, and therefore decreases cardiac output.  This is what decreases work of heart.  Since blood pressure is an indicator of cardiac output, I'm concerned BiPAP will comlicate your efforts to control her blood pressure."
"So what do you suggest?" he asked. 

Impressed that he asked me, I said, "She's breathing normal.  So how about we don't use BiPAP."

"Welp!" he said.  He hymned and hawed a few minutes, then he said, "EEEEEEeeeeee, let's just put it on and see what happens."

Well, at least I tried. 

So, what are the advantages of BiPAP?

1. IPAP increases ventilation and helps to blow off CO2
2. CPAP increases FRC and therefore keeps the lungs open so the next breath comes in easier
3. Both IPAP and CPAP help to reduce work of breathing
4. Both the IPAP and CPAP help reduce work of heart as explained above

Apperently this is not what's taught in med school.  I'll have to investigate to see if this topic was covered in the Real Physician's Creed.

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You CAN BiPAP at low settings

I am so tired of my coworkers telling me that the BiPAP settings must be greater than the following to be effective:

• IPAP = 10
• EPAP = 4

They say, and so do the BiPAP sales people, that when these settings are reached by the patient, the BiPAP is no longer needed.  

I beg to differ.  My main reason is that you cannot just make up a number and say that that number is ideal for every person.  I can say this, and no one can debate me on it, because every person is different.  

For example, yesterday I had an end stage pulmonary fibrosis patient, and her spo2 was dipping into the 70s on an NRB.  Other than that her blood gases were okay.  What she needed was some mechanism to keep her alveoli open.  I set up the BiPAP at 10/4.  Her sat shot up to 99%. Her tidal volumes were 700.  This was perfect for her.  

So my coworker came in and I gave him report on this patient.  He said, "So, then it's time to take the BiPAP off her if that's all she needs."  

I said, "I'm tired of people telling me that."

He grumbled and griped

I said, "I took her off so she could eat, and her sat dipped to the 70s.  She begged to go back on.  If you want to take her off because she doesn't need higher settings, be my guest.  If you want to increase her settings and force more air into her than she needs, be my guest." 

He grumbled and griped.  

If 10/4 is all that's needed to improve ventilation and/or oxygenation, more is not needed.  

There may be studies that show otherwise, but no study will ever compensate for common sense, at least in my book.  

Related: 

• What BiPAP settings are best

RT to titrate BiPAP

I love "RT to titrate BiPAP" orders. I wish there were "RT to titrate Vent" orders too.  I had two patients today come up from ER, both patients I set up on BiPAP.  One was put on for exacerbation of COPD and the other CHF.  Both needed it then.  But, by the time the patient was admitted, the BiPAP was no longer needed.  So I simply discontinued the therapy for both patients. 

Yes, they were sooooo happy.  I got smiles from both of them when I said, "I will keep this on standby, but I think you don't need it right now -- unless you want it.  If you want it I will be happy to put it on you."

"Oh, no no no no no." Smiles from the patient. 

Perhaps if we had more RT to Titrate vent orders there'd be a significant drop in ventilator hours.  What do you think?

How to give treatment to patient on BiPAP

I find that many respiratory therapists where I work insert the breathing treatment between the machine and the circuit.  When I ask whey they do this, they say the treatment is not indicated anyway.  They promise me when the treatment is indicated they place the nebulizer between the patient and the Y-connector.

Okay, this is fine.  And I agree that it's much easier to give a breathing treatment at the machine, especially if the patient is sleeping.  Yet if you are going to be using science here, and Lord knows we'd like physicians to base what they order on science, we ought to do the same.

Claude Guerin, et all, "Inhaled Bronchodilator Administration During
Mechanical Ventilation: How to Optimize It, and For Which Clinical Benefit?, Journal of Aerosol Medicine and Pulmonary Drug Delivery, (Volume 21, Number 1, 2008), notes the following:

With the bilevel ventilators the inhalation device should be located between the leak
port and face mask. Further studies should investigate the effects of inhaled bronchodilators on patient outcome and methods to optimize delivery of inhaled bronchodilators during noninvasive ventilation.

So while further research is needed, common sense should indicate a significant amount of the aerisolized medication would impact on the circuit, and this would be greater with longer circuits.  So it only makes sense to insert the breathing treatment closer to the patient.

Yet in a world where 80 percent of the breathing treatments are not indicated anyway, it's far easier for RTs to do the treatment the easy way, or to put it by the machine.  Yet I highly recommend you only do this when the treatment is truly not indicated.  If you don't know for sure, you're wise to do it the right way.

When do you adjust IPAP and EPAP?

Your question: I have a question about adjusting IPAP and EPAP.  How do I know when I need to adjust both?

My answer: Think of it this way:

1.   IPAP is the same as Pressure support = increased ventilation = blow off more CO2

2.  EPAP is the same as PEEP/CPAP = increased FRC = increased oxygenation

So when you want to blow off CO2 you increase IPAP, and when you want to increase oxygenation you increase EPAP

Normal starting settings are IPAP 10 EPAP 4

How to qualify for BiPAP

I believe that to qualify for bipap:

1.  Patient must be able to spontaneous breath
2.  Patient must not crash when you take them off. 

#2 there is something that's often overlooked.  Many times I've put someone on a BiPAP because their SpO2 was low and as soon as you take them off to give them a drink of water their SPo2 drops.  If they crash when you take them off the BiPAP you now have two choices:

1.  Intubate
2.  Make the patient a DNR

I can see some good arguments for this discussion, however, I have never seen a patient who could not come off the BiPAP survive unless intubated.  It's just not a good situation.  It's basically a tortuous way to end your life.

BiPAP on DNR patients: an ethical issue

As with all ethical issues there really is no right or wrong answer.  The topic of the day is this:  Is it okay to use BiPAP on DNR patients?

Argument #1:   BiPAP should not be used on DNR patients.  A perspective from Dr. Marjorie Olson:

If a patient declares a DNR status, she is basically saying she wants to die naturally.  She wants to spend the last moments of her life without an uncomfortable tube in her throat, and an uncomfortable mask over her face.  I think to place a BiPAP on such a patient would be unethical.  

Argument #2:  BiPAP  is an option for DNR patients.  A perspective from Dr. Apple:

Just because someone has declared DNR status does not mean we don't treat.  BiPAP is non-invasive procedure that can help a spontaneously breathing and compliant patient get over the hump.  

Argument #3:  BiPAP can be used if the patient is already prescribed it, and is fine with wearing it. Then it is okay to use BiPAP at any time during the DNR status.

Argument #4:  Anytime the patient is fine with trialing a BiPAP it is okay to use it. If you explain it to the patient and she's willing to try it, especially if it will make her more comfortable, then it's okay to use BiPAP on a DNR patient.

Still, it's not that easy.  Allow me to ask the following questions:

1. What if the patient is breathing is in renal failure, her SpO2 is 80-88% and falling, her pH is 7.20, and she is getting increasingly weaker.  She is in chronic pain.  Do you put a BiPAP mask on her.  She is not labored and denies breathing difficulty.  
2. Given the above situation, you are a doctor who believes in either of the above arguments, and the family insists something be done.  Do you use BiPAP then?   

Again, there is no right or wrong answer.  My opinion is if you actually think you can pull the patient over the hump, go for it.  However, if it was your grandma in that bed, would you want her to have to deal with an uncomfortable, tight, hot, stuffy, claustrophobic mask over her face?

For question number one above, I think this would be the classic patient to allow her to spend the last moments of her life without a mask over her face.  However, in the case we had today, Dr. Apple opted to give in to the request of the husband who wanted to do something.

Jeff Whitnack, RRT, wrote an article on this issue over at rtmagazine.com: "NPPV Does Not Have a Positive Role to Play in the Care of DNR/DNI.

What's your take on this issue?

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Guidelines for home BiPAP and oxygen

We in the medical profession do as we are told. That's the general logic we need to maintain our jobs and to help the hospitals we work for to get reimbursed by the Centers for Medicad and Medicair Services (CMS).

When it comes to qualifying someone for home oxygen, we are told we need to walk the patient and to monitor saturation (SpO2). If the saturation gets to 88% or less, the patient qualifies for home oxygen.

Even if you think the patient should have home oxygen, and the SpO2 does not drop to 88% during a walk, then the patient does not lie...

...which sets the ground for a little white lie. If I think someone needs home oxygen, and they only drop to 89%, I might fudge a little on my charting. Sorry, that's just the way life is. And, quite frankly, I'm sure I've saved the lives of more than one patient in this way.

I guess you can say that rules encourage lies.

Another thing we often qualify patients for is home BiPAP. Aside from doping a sleep study, sometimes we have patients that could benefit from home oxygen now, and don't have time to wait for a sleep study.

So, to qualify these patients for BiPAP we are told to chart the following:

Patients requiring BiPAP at home will need the following pulse oximetry test completed @ night prior to their discharge. During the test, the patient is to be on 2 liters of oxygen or their usual FiO2 whichever is greater.

A full five minute pulse ox test as needed, while patient is sleeping. There must be documented proof of 88% or below oxygenation for a full five minutes during the test.

Documentation example: Patient removed from BiPAP at 23:00, sleeping soundly. The patient is currently on 2 lpm oxygen. By 2304 patient pulse ox dropped to 87%. Patient remained @ or below 88% throughout next 5 minutes of test as evidenced by the following findings:

2305: 87%
2306: 86%
2307: 88%
2308: 85%
2309: 85%
2310: Patient placed back on BiPAP @ this time with 30% flow of oxygen. Pulse ox rebounded to 92%

So you can see, this is pretty dimwitted, yet it's how it is. You know in reality this situation will never happen. Nobody is going to be taken off BiPAP and fall asleep that fast. No SpO2 is going to drop and rise that fast. I've never seen it.

So I lie. I make the charting look like they want it to look, and so will you. This is a perfect example of how the people who make the policies, the rules, have no idea how things really work in the medical field.

The people who make the rules should be you and me, the people who know how it works. In reality, it works like this:

Person taken off BiPAP @ 2300. Patient does not fall asleep, yet the SpO2 drops stays at 98% until three hours later when patient falls asleep, yet I'm not around to document. SpO2 now 80%, and I come into room. I put patient back on BiPAP and SpO2 rises to 98%. I document as CMS instructs, although I'm not in room for six minutes watching the SpO2 which does change when I'm in room.