Fall 2015 Diagnostics Section Bulletin

Fall 2015 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


Technologist’s Notes: Should We Really Say “NO CAFFEINE!” Before a PFT? 

Jeffrey M. Haynes, RRT, RPFT

Many pulmonary function laboratories instruct patients to refrain from consuming any caffeine prior to testing. The reasoning behind this directive is the concern that a patient’s test results might be affected by caffeine’s influence on airway smooth muscle.

Indeed, some studies suggest that caffeine does have a bronchodilator effect, albeit it mild.1 Most of these studies, however, are quite old, and tested small numbers of subjects. It is notable that the 2005 ATS/ERS spirometry guidelines do not address the need to withhold caffeine prior to reversibility testing.2 The 1999 ATS bronchoprovocation guideline3 does recommend that caffeine not be consumed on the day of testing; however, this is supported by a single reference that showed a higher histamine PC20 in eight patients with mild asthma.4

In a more recent study, Yurach et al., evaluated the effect of a 16 oz. cup of caffeinated coffee vs. decaffeinated coffee on FEV1 and methacholine PC20.5 The investigators found no change in FEV1 or PC20. What is true, but hasn’t been studied, is the negative effect on patient mood when patients are not allowed to have their habitual morning cup of coffee!

We instruct our patients to limit caffeine on the day of testing, ideally to a single morning cup. In patients with severe lung disease, I don’t put any restrictions on caffeine because, to my knowledge, coffee, tea, or even Red Bull can’t reverse emphysema or pulmonary fibrosis.

In my opinion, restricting all caffeine on the day of testing is not warranted because it has little to no effect on pulmonary function. Moreover, I don’t particularly enjoy testing cantankerous patients whose lousy mood could have been prevented with a simple cup of coffee!

References

  1. Welsh EJ, Bara A, Barley E, Cates CJ. Caffeine for asthma. Cochrane Database Syst Rev 2010;20(1):CD001112.
  2. Miller MR, Hankinson J, Brusasco V, Burgos F, Cassaburi R, Coates A, et al. Standardisation of spirometry. Eur Respir J 2005;26(2):319-338.
  3. Crapo RO, Casaburi R, Coates AL, Enright PL, Hankinson JL, Irvin CG, et al. Guidelines for methacholine and exercise challenge testing-1999. Am J Respir Crit Care Med 2000;161(1):309-329.
  4. Henderson JC, O’Connell F, Fuller RW. Decrease of histamine induced bronchoconstriction by caffeine in mild asthma. Thorax 1993;48(8):824-826.
  5. Yurach MT, Davies BE, Cockcroft DW. The effect of caffeinated coffee on airway response to methacholine and exhaled nitric oxide. Respir Med 2011;105(11):1606-1610.

Bronchial Thermoplasty

Denise Maginnis, RRT-NPS, RPFT, RDCS
Baptist Health East, Louisville, KY

Bronchial thermoplasty (BT) is an outpatient procedure that was approved by the FDA in 2010. BT is designed to treat severe asthma by reducing the amount of excess smooth-muscle tissue in the airways.

BT involves the bronchoscopic delivery of therapeutic radiofrequency energy to the airway wall, heating the tissue to about 65 degrees C. This temperature is low enough to avoid tissue destruction and scarring but has the ability to reduce the amount of smooth muscle present in the airway wall. Less airway smooth muscle decreases the ability of the airway to constrict, and thereby reduces the frequency and severity of asthma attacks. A full course of treatment requires three visits. One BT is carried out for each lower lobe during two of the visits, and one visit is required to treat both upper lobes. Each treatment is separated by three weeks.

Pre-procedure

We began performing BT in 2012. Patients are evaluated by a pulmonologist before being scheduled for a BT procedure. BT is indicated for the treatment of severe asthma in adults whose asthma is not well-controlled with inhaled corticosteroids and long-acting beta-agonists.

The patient is prescribed prophylactic prednisone or equivalent at a dosage of 50 mg/day starting three days prior to BT and ending the day following BT to minimize procedure-related inflammation.

The day of the procedure, the patient must be reevaluated to ensure that he remains a good candidate. The procedure should be postponed for any of the following reasons:

  • Prednisone was not taken
  • Increase in asthma symptoms in the last 48 hours requiring increased use of a short-acting bronchodilator
  • Less than 14 days from completion of a course of oral corticosteroids for an exacerbation of asthma
  • Active respiratory infection, active allergic sinusitis, or other clinical instability
  • Coagulopathy
  • Inability to stop taking anticoagulants or antiplatelet agents, aspirin, or NSAIDS before the procedure

Prior to the procedure, the patient is given a fast-acting beta agonist and performs three post-bronchodilator spirometry maneuvers to assess his FEV1. Post-bronchodilator FEV1 should be greater than 85% of the patient’s usual value. If FEV1 is decreased, or SpO2 is less than 90% on room air, treatment will be postponed.

Post-procedure

Following BT, the patient is given a fast-acting beta agonist and performs three post-bronchodilator spirometry maneuvers to assess FEV1. Post-bronchodilator FEV1 should be greater than 80% of pre-treatment value. If the FEV1 is less than 80% of pre-treatment value, the physician must be notified.

Post-procedure assessment includes:

  • Spirometry, breath sounds, and vital signs.
  • Verifying the patient has gag reflex and is able to take liquids.

Following a 2-4 hour recovery period, the patient may be discharged, if he is clinically stable.

Patients should be cautioned about potential adverse reactions that may occur, including:

  • Worsening of asthma symptoms
  • Upper and lower respiratory tract infections
  • Hemoptysis
  • Fever
  • Cough
  • Acute sinusitis
  • Anxiety
  • Headache
  • Throat pain or irritation
  • Chest pain

Study shows good outcomes

According to the Asthma Intervention Research 2 (AIR2) trial, patients with severe asthma showed significant improvement after BT, compared to sham-controlled patients. This study randomized patients who regularly took flucticasone-salmeterol 500/50. Two-thirds of the patients received BT and one-third received a sham procedure. All follow-up and assessment visits were conducted by a blinded assessment team. The clinical trial was conducted at 30 investigational sites in six countries. Subjects in the AIR2 clinical trial were followed for five years.

The AIR2 study showed the following one year after BT:

  • 32% decrease in severe asthma exacerbations (requiring systemic corticosteroids)
  • 84% reduction in emergency room visits for respiratory-related symptoms
  • 66% fewer asthma-related days lost from work, school, and other activities
  • 79% of patients reported a significant improvement in their asthma-related quality of life

Key findings reported after five years included:

  • 48% decrease in severe exacerbations compared to the year prior to receiving BT
  • 88% decrease in emergency room visits for respiratory symptoms compared to the year prior to receiving BT
  • Comparison of HRCT images before BT and at five years post BT treatment showed no structural changes in the airways due to BT that were of clinical significance
  • No increase in hospitalizations for respiratory symptoms over the course of five years.

BT appears to be a major innovation in the treatment of severe asthma. It has been exciting to be a part of this innovation. I have not witnessed any significant adverse reactions to BT. Our patients report satisfaction with the outcomes of the procedure.


Eucapnic Voluntary Hyperventilation

Martin Rohrer, BS, RRT, CPFT
Lester E. Cox Medical Center, Springfield, MO

Exercise induced bronchospasm (EIB) results in acute narrowing of the lower airways. EIB symptoms include wheezing, chest tightness, cough, fatigue, mucus production, and dyspnea. EIB is thought to occur in 40-90% of asthmatic patients. EIB may be more likely to occur in high-ventilation sports (e.g. running, soccer), but can occur in any setting. The genesis of EIB is thought to be due to dry air ventilation causing airways to narrow by osmotic and thermal changes as water evaporates from airway surfaces.

Eucapnic voluntary hyperventilation (EVH) is an indirect bronchial challenge test designed to identify and characterize airway hyper-responsiveness. During an EVH test the patient breathes dry compressed air gas for six minutes at target breath rates up to 40 breaths per minute to achieve a minute ventilation of ~85% of the calculated maximum voluntary ventilation (MVV). An adequate EVH test requires that the minute volume is at least 60% of the MVV. A positive challenge is a ≥10% reduction in FEV1 when compared with the baseline value.

EVH is approved by the Olympic Committee as an indirect bronchial challenge test for the detection of EIB. In some settings EVH may be a better diagnostic choice than an exercise treadmill/cycle ergometer challenge test.

EVH procedure

EVH indications:

  • Suspicion of EIB
  • Determination of medication efficacy

 Exclusion criteria: 

  • Pre-test FVC and FEV1 <60% of predicted
  • Failure to withhold medications that would interfere with the accuracy of an EVH test (e.g., albuterol)

 Hazards and precautions: 

  • Bronchoconstriction
  • Lung hyperinflation
  • Coughing
  • Dizziness, light-headedness, or chest pain related to spirometry testing

 Equipment/supplies/meds:

  • Spirometry system and EVH testing software
  • Disposable mouthpiece/filter and nose clips
  • Hans Rudolph 30 liter non-diffusing collection system
  • Pulse oximeter
  • Medical grade compressed gas: 5% CO2, 21% Air, Balance N2; (5% CO2 added to maintain eucapnia)
  • 2-stage regulator with high pressure hose
  • Bronchodilator delivered by MDI or nebulizer
  • Emergency equipment
  • Stethoscope

Before starting an EVH test, explain and demonstrate the test requirements to the patient. Instruct the patient how to quickly remove nose clips, swallow, and return to EVH breathing. The technologist must monitor the patient for symptoms throughout testing.

rohrer_1

Figure 1. A patient performing an EVH test.

The procedure listed below is specific to the SensorMedics Vmax Encore with EVH testing software but is generalizable to EVH on any system.

  1. Obtain baseline spirometry values. Spirometry should be performed according to ATS/ERS recommendations.
  2. Calibrate the system for EVH testing.
  3. Obtain baseline EVH readings (patient on mouthpiece and nose clips for 30 seconds to one minute breathing room air).
  4. To start the hyperventilation phase have the patient breathe at or above tidal volume with breath rate approximately 40 breaths/minute or higher for six minutes (60-85% of the MVV), with no leaks and nose clips in place.
  5. Increase gas flow to 30 liter bag as necessary to keep bag at least ½ full.
  6. Monitor heart rate and SpO2.
  7. Check patient for symptoms throughout testing: chest tightness, wheezing, dyspnea.
  8. After six minutes return to room air and recovery (add time as necessary to make up for any swallowing time).
  9. Go to spirometry level 1 and perform two FEV1 maneuvers immediately following the end of EVH test.
  10. Repeat spirometry at 3, 5, 10, 15, and 20 minutes or until a greater than 10% decrease in FEV1 is recorded.
  11. If needed, administer bronchodilator.
  12. Wait ten minutes then repeat spirometry.
  13. If the post BD FEV1 is within 10% of the baseline level, testing is complete.
  14. If the patient does not recover after one dose of bronchodilator, repeat the bronchodilator, wait an additional ten minutes, and repeat spirometry.
  15. Testing is complete when the patient’s FEV1 is within 10% of the baseline level.
rohrer_2

Figure 2. The first page of our EVH report.

Figure 2 shows the first page of our EVH test report. The top half shows three graphs, which plot in real time as the patient is testing. The first reflects minute ventilation vs. time, giving us a visual indication of how to encourage the patient to maintain a proper breathing pattern. The second graph shows end tidal CO2 vs. time. The third graph represents respiratory rate and breath volume vs. time. Again, we want deep and fast breaths to cause as much airway drying and cooling as possible.

The lower half of the page shows the baseline spirometry vs. repeat spirometry made during different stages of the EVH test. Notice on the first spirometry post EVH, (labeled “dose 1”), spirometry showed a 29% decrease in FEV1 from baseline, also seen as the red expiratory flow/volume loop. This reflects a positive test result and no more post EVH spirometry measurements are necessary. The therapist gave a bronchodilator and the results are reflected in the last flow/volume loop coming back to baseline.

rohrer_3

Figure 3. EVH response curve

Figure 3 shows the second page of our EVH report. This EVH response curve graphically reflects the 29% drop in FEV1 from baseline. Although the graph suggests a PC 15 FEV1 as the positive cutoff point, this is due to software limitations. Our actual cutoff point for a positive test is a 10% decrease in FEV1.

EVH testing has given us a good, reliable, indirect bronchial challenge test that is easy to set up and also fairly inexpensive. Currently we charge under CPT code 94070.


Telephone Reminder Calls Reduce Outpatient Absenteeism

Jeffrey M. Haynes, RRT, RPFT

Outpatient absenteeism hurts everyone. Firstly, patients miss their scheduled PFT, which may delay proper diagnosis and treatment. In addition, the patient’s follow-up appointment with his physician may need to be rescheduled if decisions cannot be made without guidance from PFT data. Outpatient absenteeism also affects other patients who have to wait longer to get an appointment because the absentee patient has to be rescheduled into a second patient time slot. Absenteeism clearly reduces the efficiency and cost effectiveness of a pulmonary function laboratory.

A simple and effective way to reduce absenteeism is to provide patients with an appointment reminder call. Appointment reminder calls have been used in many service industries, including automotive repair, dental care, and beauty salons. Reminder calls have been shown to be effective in PFT labs. In our PFT lab the absentee rate was 11.6% without reminder calls and 4.7% with reminder calls.1 (See Figure 1)

haynes

Reference

  1. Haynes JM, Sweeney EL. The effect of telephone appointment-reminder calls on outpatient absenteeism in a pulmonary function laboratory. Respir Care 2006;51(1):36-39.

Quarterly Case Report: A Strange Case of Nitrogen Washout

Jeffrey M. Haynes, RRT, RPFT

During a multiple-breath nitrogen washout, the technologist observed sudden dips in the exhaled nitrogen concentration. (See red arrows in Figure 1.). Near the end of the test the nitrogen concentration changed directions and began to rise. (See green arrow in Figure 1.)

haynes_quarterly

Figure 1. Multiple breath nitrogen washout

Questions:

  1. What is the most likely cause of the dips in nitrogen concentration?
  2. What explains the rise in nitrogen concentration at the end of the test?

Answers:

  1. The dips in nitrogen concentration are most likely due to “deadspace” breaths. These are very small breaths with a very high VD/VT ratio. Since the patient breaths 100% O2 during a nitrogen washout, these small breaths will have a high O2 concentration and a low nitrogen concentration. Once the patient takes normal sized breaths, the nitrogen concentration returns to the expected downward trajectory.
  2. The rise in nitrogen concentration near the end of the test is due to leak, which contaminates the system with nitrogen-rich room air.

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