Fall/Winter 2017 Diagnostics Bulletin

Fall/Winter 2017 Diagnostics Section Bulletin

Editor
Jeffrey M. Haynes, RRT, RPFT

Pulmonary Function Laboratory
St. Joseph Hospital
Nashua, NH
Work Email: jhaynes@sjhnh.org
Home Email: jhaynes3@comcast.net

Chair:
Katrina Hynes, BAS, RRT, RPFT
Supervisor
Mayo Clinic Pulmonary Evaluation Laboratory
Rochester, MN 55905
(507) 284-4545
Hynes.Katrina@mayo.edu

Former Chair
Matthew J O’Brien, RRT, RPFT
Pulmonary Diagnostic Lab
University of Wisconsin Hospital and Clinics
600 Highland Ave Room E5/520
Madison, WI 53792-5772
(608) 263-7001
Fax: (608) 263-7002
mobrien@uwhealth.org


Notes from the Chair

Katrina Hynes, MHA, RRT, RPFT

Interest in the Diagnostics Section continues to grow due to the professional collaboration and comradery that you all bring to the membership. Because of you, the value of membership in the section has never been higher and our membership numbers are growing. I thank each of you for what you bring to the membership. Together we blend expert knowledge, clinical curiosity, and innovative thinking to help our profession evolve and provide high quality diagnostics to our patients.

As the chair of the section, I take great pleasure in seeing aspiring leaders grow within our section. The long-term success of the section depends on the willingness of experienced practitioners to mentor younger members. As a result, we create a professional growth and development environment that affords them the opportunity to reach their potential within the AARC, section, and our profession.

This past summer I announced that Jeffrey Haynes, RRT, RPFT, FAARC, decided to step down as Bulletin editor. Jeff was very impressed by a Bulletin submission from Jennifer Weltz-Horpedahl, BSRT, RRT-NPS, RPFT, and invited her to consider taking over as Bulletin editor. We’re happy to announce that Jenny eagerly accepted the challenge and will assume the role as editor. To assist with the Bulletin responsibilities, I decided to add an assistant editor position. D’Aun Flesher, BSRT, RRT-NPS, AE-C, will assume this role, working collaboratively with Jenny.

Jenny has been an RT since 2004. She works at Kadlec Regional Medical Center in Washington State. I enjoyed working with Jenny when we served as guest consultants on the National Board for Respiratory Care’s Pulmonary Function Examination Committee. I have also had the pleasure of interacting with Jenny as an advisor and resource to her consistent efforts for improving quality within her organization. As she states, “Quality and providing my patients a pleasant test experience are very important to me.” She is a testament to quality improvement and care. When Jenny isn’t working with patients, she enjoys sewing, yoga, and travel.

D’Aun is an outpatient asthma educator and freelance copy editor in Albuquerque, NM. She has been a peer reviewer for Respiratory Care since 2012 and currently serves as the board secretary for the Junior League of Albuquerque. She graduated with a bachelor of science degree in respiratory care from the Oregon Institute of Technology (OIT), where she received the Outstanding Scholar Award.

While attending OIT, she worked as a copy editor and eventually editor-in-chief for their weekly campus newspaper, which was presented with the school’s Most Improved Program award during her time on staff. Her professional background includes fixed-wing and ground transportation, Level III NICU care, and diagnostics. D’Aun is currently pursuing green belt certification in Lean Six Sigma and learning Spanish.

I would like to say “thank you” to Jeff for his work as Bulletin editor and his commitment and dedication to the section. Jeff and I are confident that the membership will enthusiastically support Jenny and D’Aun as the new Bulletin editors.

If you would like to contribute an article to the next edition of the Bulletin, email it to Jenny and/or D’Aun by February 1, 2018.


Technologist’s Notes
Pulmonary Function Testing: The Value of You

Jeffrey M. Haynes, RRT, RPFT, FAARC

Being a good pulmonary function technologist is not easy. Indeed, good technologists are hard to find. By the time a student finishes his or her PFT rotation with me, almost without exception, he or she comments: “I had no idea pulmonary function testing was this complex.”

My guess is that most pulmonologists don’t appreciate the complexity of pulmonary function testing either. Moreover, in our busy work life it’s probably pretty easy for us to underappreciate the complexity and importance of our work as well.

But let’s face it, there are a lot of moving parts and grenades to juggle to ensure patients are tested correctly and the laboratory runs safely and efficiently. The pulmonary function technologist must understand pulmonary physiology, testing protocols, diagnostic equipment and computer technology, reference equations, billing, coding, inventory management, scheduling, quality control, quality assurance, and whatever else is piled on your plate. Not just anyone can do what you do.

Without a doubt, the most important component of pulmonary function testing is the technologist. Yes, the technologist is even more important than the doctor!

If a doctor disputed this idea I would ask him or her if he or she would like to switch roles for a day: “OK doc, you perform spirometry, diffusion capacity, lung volumes, and a six-minute walk test on the next tardy patient who has dementia and a hearing impairment, and I’ll do the two-minute interpretation.”

The undeniable truth is that most patients (even the elderly) are capable of performing tests correctly, and most PFT systems will produce reasonably accurate results if maintained properly. Without question, an incompetent and/or indolent technologist is usually the cause of chronic and recurrent low-quality PFTs.

Poor quality testing can be disastrous for patients. A patient recently asked me, “So you do this all day long — don’t you get sick of doing the same tests over and over again?” I thought about this for a moment, explained to the patient that the technologist was the usual cause of inaccurate tests, then continued on to say that, “If I don’t do the testing correctly a patient could be misdiagnosed, lose his job, have her medications mistakenly discontinued, or be denied potentially life-saving surgery. I enjoy a great sense of satisfaction knowing that these things are not going to happen to any patient who walks through that door. That’s why I don’t get sick of doing the same tests over and over again.”

Pulmonary function testing is not easy. It can be frustrating at times, and mentally and physically exhausting. However, the work that you do is important; to many patients it is vital. So take some time and reflect on your career, be proud of your professionalism and dedication to your patients, and embrace the value of you.


Electromagnetic Navigational Bronchoscopy: Extending Our Reach

D’Aun Flesher, BSRT, RRT-NPS, AE-C

 

A promotional image of the ENB system. Courtesy of Medtronic.

E.L. Doctorow once compared writing a novel to driving a car at night: “You never see further than your headlights, but you can make the whole trip that way.”

Those of us in diagnostics know that this is certainly not the case in bronchoscopy!

Bronchoscopy is a useful diagnostic tool, but it doesn’t get us very far into the lungs. If lungs were cities and our airways the roads, they’d be confusing, with their twists and turns, forks in the road, and low visibility. Moreover, every “bronchial street” looks the same! Even if we had a scope that was thin and long enough to reach and fit into smaller bronchioles, how would the physician find the way to his destination?

For patients with peripheral lesions (past the third order of bronchi), providers typically have had to resort to open-lung (surgical) or transthoracic needle biopsy, or other invasive options, all of which come with increased risks compared to bronchoscopy.

Fortunately, we can now use bronchoscopy to reach even the farthest corners of the lungs with a new technology called electromagnetic navigational bronchoscopy (ENB). I often describe it to the layperson as “GPS for your lungs” – it can guide us through the pathways formed by the bronchi and bronchioles to our destination.

RTs play a big role

ENB takes longer to prepare for than traditional diagnostic bronchoscopy. Prior to ENB the patient undergoes a CT of the chest. Computer software uses the CT images to create a virtual map of the patient’s tracheobronchial tree. The physician uses the virtual map to plan her path from the trachea to the lesion in question. Usually the physician creates several plans, in case she finds herself unable to get to her destination via the primary route.

More than 850 hospitals are currently using ENB. At our facility in Albuquerque, NM, respiratory therapists manage the bronchoscopy laboratory and are responsible for everything from setup to cleaning and turnaround between patients. In addition to the standard bronchoscopy setup, we are responsible for a separate computer cart, the location board, endobronchial ultrasound, biopsy forceps/brush/needle or other tools, and a special bronchoscope with an adapter and a wider channel to accommodate the ENB sensor catheter.

When the patient is ready for the procedure, the physician brings the planned bronchoscopic pathway on a USB storage drive. The patient is positioned supine with the location board under his back, which communicates with three location sensors that are placed on the patient’s chest. One is on the sternum, approximately two fingers below the suprasternal notch. The other two are placed laterally and inferiorly, guided by and visualized on a computer.

After the patient is positioned and sedated, the software’s registration process merges the patient’s CT with the data from the location sensors and generates a virtual bronchoscopy. This and other visual tools orient the physician in real time to the exact position of the bronchoscope in the lungs, so he can guide the scope to the lesion.

Reaching the target

The bronchoscope is fitted with an extended working channel, which accepts the locatable guide (the sensor catheter that communicates with the location sensors and board to navigate to the lesion). Once the target is reached, the scope with the working channel is locked in place, the locatable guide is removed, and an ultrasound probe is used to ensure positioning within the desired area.

If the ultrasound shows that the scope is positioned near abnormal tissue, then the physician can retrieve samples. In our facility, pathology personnel are present in the bronchoscopy suite to prepare slides and interpret the samples mid-procedure. This enables the physician to provide the patient with a diagnosis as soon as her sedation wears off.

In addition to providing a less invasive way to diagnose peripheral lung nodules, ENB can be used to accurately place fiducial markers and mark areas in need of resection.

ENB is an exciting technology that both improves the care of patients and offers an opportunity for respiratory therapists with an appetite for learning to expand their practice.


A Methacholine Challenge Protocol Based on the 2017 ERS Technical Standards

Jeffrey M. Haynes, RRT, RPFT, FAARC

As most of you are aware, the European Respiratory Society (ERS) recently published a new technical standard for methacholine challenge testing.1 Two of the most important changes to the 1999 American Thoracic Society guideline are the elimination of deep inhalations during methacholine delivery and reporting the provocative dose of methacholine resulting in a 20% decline in the forced expiratory volume in the first second (PD20; FEV1) rather than the provocative concentration of methacholine resulting in a 20% decline in the FEV1 (PC20).

Avoidance of deep, full breaths during methacholine delivery is not a new concept. It has been known for many years that deep inhalation has the power to protect airway smooth muscle from provoked bronchoconstriction. Indeed, multiple studies have shown that many patients with mild airway hyper-responsiveness (AHR) and asthma will have a “positive” tidal breathing methacholine challenge test (MCT) and a “negative” deep inhalation dosimeter MCT.2-3

The physiology of deep inhalation has been an interest of mine for many years. Accordingly, while we have always used the dosimeter MCT method, we instruct our patients not to take a full breath of methacholine (e.g. “only inhale a little above a normal breath”). For our updated protocol, I decided to ditch the dosimeter and use the tidal breathing method (with a twist).

The recommendation to report PD20 (and not PC20) is based on the fact that PC20 is affected by the methacholine concentration and the output of the nebulizer.4-5 For example, a patient could have very different PC20 values at laboratories that do not use the same methacholine concentrations and nebulizers. However, because the PD20 accounts for the methacholine concentration and nebulizer output, the patient would have a similar PD20 at different laboratories even though the methacholine concentrations and nebulizers are different.

The 2017 ERS technical standard includes an interpretive strategy based on PD20 (see Table 1). My goal was to design a protocol that would allow the use of the non-cumulative PD20 interpretative strategy.

Table 1. 2017 ERS Methacholine Challenge Interpretation Categories

PD20 (mcg)                              Interpretation

>400                                         Normal

100-400                                   Borderline AHR

25-100                                      Mild AHR

6-25                                          Moderate AHR

<6                                             Marked AHR


The ERS document states that “inhalation may be by tidal breathing using a breath-actuated or continuous nebulizer for one minute or (more), or by a dosimeter with a suitable breath count.”

My preference is to use a specific breath count instead of time to better standardize testing. For example, in one study using 20 seconds of tidal breathing, the breath count ranged from 3-16 breaths.5

I decided to use the Aeroeclipse II breath-actuated nebulizer and the quadrupling concentration protocol listed in the ERS standards without a diluent step (see Table 2). I have never used a diluent step, and while the ERS standard supports its use, they make a very good case for why it is not necessary:

The starting concentration of methacholine was chosen so that only the most hyper-responsive patients will respond and the use of a diluent control does not improve the safety of the test. The end-point is not affected by starting with a diluent. The addition of a diluent control adds 4-5 min to each test. While only 1% of patients tested using a diluent (control) respond to the diluent with a 20% fall in FEV1, a 10% change occurred 5.8% of the time. Variability in lung function during the diluent step may decrease the accuracy of the measurement of AHR. The clinical meaning of a positive response to the diluent is unknown; some patients may be hyper-responsive to the diluent (saline) or may be experiencing FVC maneuver-induced bronchoconstriction.1

Table 2. Quadrupling Methacholine Protocol

Concentration protocol (mg/mL):

0.0625

0.25

1

4

16


I chose a 6-breath protocol as a surrogate for 20 seconds of tidal breathing. El-Gammal et al. found that 20 seconds of tidal breathing resulted in an average of six breaths.5 I calculated the delivered dose based on the example listed in appendix D of the ERS technical standard for a 16 mg/ml concentration:

2.70 mg/min x .76 x 20/60 min = .68 mg (680 µg)

where:

2.70 mg/min is the output of the breath-actuated nebulizer

.76 is the fraction of aerosol delivered to the mouth

For other dilutions I used the equation listed below:

Dose = [concentration (mg/mL)/16 mg/mL] x 680 ug

Results:

                        Concentration            Dose Delivered to the Lungs

Step 1:             0.0625 mg/mL            2.6 ug

Step 2:             0.25 mg/m                  10.6 ug

Step 3:             1 mg/mL                     42.5 ug

Step 4:             4 mg/mL                     170 ug

Step 5:             16 mg/mL                   680 ug

My conclusion is that a 6-breath (~20-second) quadrupling dose protocol using a breath-actuated nebulizer allows the use of the non-cumulative ERS PD20 interpretation strategy.

References

  1. Coates AL, Wanger J, Cockcroft DW, et al. ERS technical standard on bronchial challenge testing: general considerations and performance of methacholine. Eur Respir J 2017;16:1601526.
  2. Todd DC, Davis BE, Hurst TS, Cockcroft DW. Dosimeter methacholine challenge: comparison of maximal versus submaximal inhalations. J Allergy Clin Immunol 2004;114(3):517-519.
  3. Cockcroft DW, Davis BE, Todd DC, Smycnuik AJ. Methacholine challenge, comparison of two methods. Chest 2005;127(3):839-844.
  4. Dell SD, Bola SS, Foty RG, Marshall LC, Nelligan KA, Coates AL. Provocative dose of methacholine causing a 20% drop in FEV1 should be used to interpret methacholine challenge tests using modern nebulizers. Ann Am Thorac Soc 2015;12(3):357-363.
  5. El-Gammal AI, Killian KJ, Scime TX, Beaudin S, Schlatman A, Cockcroft DW, Gauvreau GM. Comparison of the provocative concentration of methacholine causing a 20% fall in FEV1 between the AeroEclipse II breath-actuated nebulizer and the Wright nebulizer in adult subjects with asthma. Ann Am Thorac Soc 2015;12(7):1039-1043.

Massive Bronchodilator Response

Jeffrey M. Haynes, RRT, RPFT, FAARC

A 67-year-old male with known asthma presented to the pulmonary function laboratory for a complete PFT and methacholine challenge. The patient’s asthma was treated with salmeterol twice daily and albuterol as needed; both were withheld on the day of testing.

The first test performed was fraction of exhaled nitric oxide, which was high at 79 parts per billion (>50 ppb). Pre-bronchodilator results are shown below:

Spirometry indicated very severe obstruction with all three values below the lower limit of normal (z-score -1.645).

 

 

 

 

 

 

 

Lung volumes via plethysmography indicated hyperinflation (TLC above the upper limit of normal [ULN]) and air-trapping (FRC, RV, and RV/TLC above the ULN).

 

Specific airway conductance (sGaw) via plethysmography was markedly reduced.

Diffusion capacity (DLCO) and transfer coefficient (KCO; formerly named DLCO/VA) were within the normal range. However, the gap between VA and TLC was 2.13 (VA/TLC .75), suggesting poor distribution of the DLCO test gas. This is an expected finding since airway obstruction in asthma is heterogeneous. So-called ventilation defects (patchy areas of constricted airways) produce adjacent bronchodilation due to airway-parenchymal interdependence (i.e. radial traction). The test gas will therefore preferentially ventilate the dilated regions maintaining a normal KCO.

Methacholine challenge testing was clearly contraindicated on the basis of severe obstruction, so bronchodilators (albuterol, ipratropium) were administered via a breath-actuated nebulizer. The pre- and post-bronchodilator results are shown below:

This is a massive response to bronchodilator with a 188% increase in FEV1. While FVC and FEV1 normalized, obstruction was still present since FEV1/FVC and sGaw remained below the lower limit of normal (LLN). Lung volumes normalized with a reversal of hyperinflation (TLC <ULN) and air-trapping (FRC, RV, and RV/TLC all < ULN).

Interestingly, there was a significant increase in DLCO that was not accompanied by a change in KCO. In addition, the VA to TLC gap decreased from 2.13L to .18L, and VA/TLC rose from .75 to .98. These findings suggest that the increase in DLCO was due to a larger volume of test gas reaching the alveoli (reversal of ventilation defects) rather than a significant change in the rate of CO transfer (KCO).

This case raises a number of important considerations. First, it is questionable why this patient would need a methacholine challenge when the pre-test probability of asthma was so high. The order for a methacholine challenge required withholding his asthma control medication, which may have unnecessarily exposed the patient to risk. Such poor asthma control also raises the question of poor compliance and/or inhaler technique. I asked the patient to show me his inhaler technique, which was quite poor. The patient was issued a spacer and received training. The elevated fraction of exhaled nitric oxide suggested that this patient would benefit from inhaled corticosteroids.

Finally, such a massive bronchodilator response should raise some suspicion regarding spirometer accuracy. Just to be thorough, I repeated the calibration verification of the non-heated pressure differential (metal screen) pneumotach, which under the right conditions can accumulate moisture. The reading was a perfect 3.00 L. The calibration verification took less than 30 seconds to complete, not much of a burden to be certain that the patient was properly diagnosed and treated.


Some Words of Appreciation

Jeffrey M. Haynes, RRT, RPFT, FAARC

I have really enjoyed serving as the editor of the Diagnostic Specialty Section Bulletin. At times it has been a lot of work, but always a labor of love. Thank you to Debbie Bunch of the AARC for your support and forbearance when I didn’t quite make my deadlines. I also want to extend gratitude to our Section Chair Katrina Hynes for giving me the opportunity to serve as editor and helping me recruit authors. Lastly, I want to thank all the members who agreed to write articles for the Bulletin during my time as editor:

Danielle Bonagura, RRT

Balamurugan Panneerselvam, BS, RST, RPSGT, CPFT

Gregg Ruppel, MEd, RRT, RPFT, FAARC

Matthew O’Brien, MS, RRT, RPFT, FAARC

Holly Wilson, RPFT

Elizabeth Koch, BHS, RRT, RPFT

Jennifer Weltz Horpedahl, RRT-NPS, RPFT, AE-C

Richard Johnston, CPFT

Ann Wilson, BS, RRT, RPFT

Jason Blonshine, RRT, CPFT

Ralph Stumbo, RRT, CPFT

Denise Maginnis, RRT-NPS, RPFT, RDCS

Martin Rohrer, BS, RRT, CPFT

Katrina Hynes, MHA, RRT, RPFT

Dan Alamillo, BS, RRT-NPS, CPFT

D’Aun Flesher, BSRT, RRT-NPS, AE-C

I learned a lot from all of you and hope you’ll make more contributions to the Bulletin.


Section Connection

Recruit a new member: Know an AARC member who could benefit from section membership? Ask them to call AARC Customer Service at (972) 243-2272 to add section membership to their overall membership package.

Section discussion list: Go to the section website and click on “Discussion List” to start networking with your peers via the AARC’s social networking site, AARConnect.

Next Bulletin deadline: Spring-Summer Issue: February 1, 2018